Background: Rheumatic heart disease affects primarily cardiac valves, it could involve the myocardium either primarily or secondary to heart valve affection. The influence of balloon mitral valvuloplasty (BMV) on left ventricular function has not been sufficiently studied.Aim: To determine the influence of balloon mitral valvuloplasty (BMV) on both global and regional left ventricular (LV) function.Methods: Thirty patients with isolated rheumatic mitral stenosis (MS) were studied. All patients had cardiac magnetic resonance imaging (CMR) before, 6 months and 1 year after successful BMV. LV volumes, ejection fraction (EF), regional and global LV deformation, and LV late gadolinium enhancement were evaluated.Results: At baseline, patients had median EF of 57 (range: 45–69) %, LVEDVI of 74 (44–111) ml/m2 and LVESVI of 31 (14–57) ml/m2 with absence of late gadolinium enhancement in all myocardial segments. Six months following BMV, there was a significant increase in LV peak systolic global longitudinal strain (GLS)  and global circumferential strain (GCS) . At 1 year, there was a trend towards decrease in LVESVI  with a significant increase in LV EF . A further significant increase, compared to 6 months follow up studies, was noticed in GLS  and GCS (−19.4 vs. −17.8 p = 0.03).Conclusions: Successful BMV is associated with improvement in global and regional LV systolic strain which continues for up to 1 year after the procedure. Although, the incidence of rheumatic fever and its complications has declined in developed countries, the disease is still a major health problem in many developing countries . It is eThe procedure of balloon mitral valvuloplasty (BMV) has been first described in 1984 by a Japanese cardiac surgeon called Kanji Inoue . The maiImpaired left ventricular (LV) systolic function has been reported in around 30% of patients with MS , while iChanges taking place in LV following BMV have been a subject of investigation and debate over the past years. Different diagnostic tools including cardiac catheterization and angiocardiography , echocarThe present study aimed to determine the impact of BMV on LV volumes, global, and regional function using CMR, 6 months and 1 year following BMV in patients with isolated rheumatic MS.The study was an observational prospective cohort study that took place at a tertiary referral hospital. The study included 30 consecutive patients with isolated rheumatic MS who underwent successful BMV, and a control group of 12 healthy volunteers without known prior cardiovascular disease.2) and favourable valve morphology  in the absence of left atrial thrombus or moderate-to-severe mitral regurgitation  < 1.5 cmgitation . A succeications , 19. ExcPatients referred to the hospital were first screened for eligibility for this study. Eligible patients had baseline workup that included clinical evaluation, electrocardiogram (ECG), echocardiography study [transthoracic and trans-oesophageal (TEE)], CMR imaging and invasive haemodynamic study before BMV. Only patients who had a successful procedure were recruited and then had two follow up studies at 6 months and 1 year after the procedure. Medical treatment, in the form of beta-blockers and a small dose of diuretics, was initiated at least 6 months pre-procedural and was kept unchanged throughout the follow-up period. On the other side, individuals in the control group were evaluated clinically and had ECG and trans-thoracic echocardiography to exclude any cardiovascular disease and then had a complete CMR imaging evaluation.via Philips iE33 with 2.5 MHz sector transducer. All studies were done according to the criteria provided by the American Society of Echocardiography (ASE) (Transthoracic echocardiography images were obtained hy (ASE) . LV end-via right and left heart catheterization immediately before BMV. Tracings were obtained using AXON Sensis XP  using a standardized protocol under stable conditions. Left atrial pressure (LAP), mean pressure gradient, systemic vascular resistance (SVR), pulmonary artery pressure (PAP), and cardiac index were measured.Haemodynamic assessment was performed All patients had percutaneous BMV by antegrade trans-septal approach with the use of the Inoue balloon catheter  using a standardized technique . ImmediaCMR examination was performed using 1.5 Tesla Siemens Aera , with 25-m T/M maximum gradient strength and a phased array cardiac coil of 48 channels.Systolic and diastolic volumes were assessed using a retrospective ECG-gated steady-state free precession (SSFP) sequence during breath-holding. Vertical long-axis 2- and 4- chamber views and short-axis views consisting of 12–14 contiguous slices were acquired, covering both ventricles from the base of the heart to the apex.For the tissue characterization (viability) studies, a bolus of 0.2 mmol/kg of Gadolinium was infused at an injection rate of 4 ml/s followed by a bolus of 20 ml of normal saline, infused at the same rate. Delayed enhancement 3D acquisitions were acquired in diastole 10 min after Gadolinium injection with a time of inversion (TI) of 175–300 ms. Tissue characterization studies were performed only once for MS patients at baseline.2, matrix 216 × 256, TR/TE 9.0/4.0, flip angle 15°) was used in the cine mode. A rectangular grid with a spacing of 8 mm was applied. The acquisition window for one cardiac phase was 70–90 ms. resulting in a temporal resolution of 35–45 ms.Tagging MR images were performed in the short heart axis orientation and then in apical four-chamber, apical two-chamber and apical long-axis planes. Three short-axis planes were obtained . A segmented two dimensional electrocardiographically triggered fast low angle shot pulse sequence . After the determination of the end-diastolic and the end-systolic frame on the first basal slice to show circumferential myocardium at both diastole and systole, the endocardial contour was traced manually. All volumes were calculated automatically by summing the areas in the entire series of short-axis cine images . VolumesTagged MRI images were analyzed quantitatively using the software HARP . After adjusting the Region of Interest (ROI) and manual defining of the endocardial and epicardial borders, myocardial strain curves throughout the cardiac cycle were automatically generated for the left ventricular 17 segments. Peak systolic longitudinal strain was measured for different myocardial segments from the tagged apical 2, 3, and 4 chambers views while peak systolic circumferential strain was estimated from tagged short axis views. Strain was measured as the change in myocardial segment length relative to its end-diastolic length. Global strain values were calculated as the mean value of strain measurements of the LV segments. Negative strain values denoted myocardial shortening , 23 Fig, 3.Statistical analysis was performed using Statistical Package for Social Sciences, version 16 (SPSS 16). Firstly, all variables were tested for normality using Kolmogrov-Smirnov test; If the test was significant, non-normality was accepted otherwise double-check using graphs, skewness and kurtosis were required to confirm normality. All the quantitative variables in this research were not normally distributed and accordingly are presented as median (range). Qualitative data are presented as number (percentage).Variables were compared between two related samples using Wilcoxon test. Categorical variables were compared using Chi-square analysis. Bivariate correlations were performed using Spearman correlation coefficient. Probability value of < 0.05 was considered statistically significant.Delta (Δ) for a specific parameter was calculated by subtracting the value of this parameter at follow up from its corresponding value at baseline study.Among 78 patients screened for eligibility of BMV, 51 patients had BMV over a 1 year period. Three patients had unsuccessful procedure where two patients had post-procedural severe mitral regurgitation and were referred to surgery, and the procedure failed to attain a satisfactory valve area in the third one. Eighteen patients were excluded due to various reasons including pregnancy, claustrophobia, and refusal to participate in the study. The remaining 30 patients, who had a successful procedure, were included in the study and had two follow up visits at 6 and 12 months after BMV.The demographics of the study population, clinical characteristics, baseline echocardiographic and heamodynamics data of the patients are summarized in 2, p = 0.32), significantly larger LVESVI  and significantly lower LV ejection fraction . MS patients had lower regional peak systolic longitudinal and circumferential strain in all LV myocardial segments comapred to control group. Peak systolic global circumferential strain (GCS) and global longitudinal strain (GLS) were significantly lower in MS patients .Compared to the control group, patients with MS had similar LVEDVI  vs. 12.5 (8–24) mmHg, p < 0.001] and a significant drop in PASP .Following BMV, as evaluated by trans-thoracic echocardiography, there was a significant increase in MVA [1.9 (1.7–2.3) vs. 0.9 (0.6–1.3) cm2, p = 0.079) associated with a significant improvement in LVEF   .Regional strain: At 1 year follow up, an improvement in peak circumferential systolic strain values was noted in all LV myocardial segments; this improvement showed statistical significance in 15 segments and trend toward significance in the remaining two segments. Similarly, all LV myocardial segments showed significant improvement in peak longitudinal systolic strain values at 1 year  with a further improvement at 1 year . Similar changes were observed in GCS with a significant improvement at 6 months  and a further improvement at 1 year . However, at 1 year following BMV, both GLS and GCS values remained significantly lower than those of the control group  (ctively) , 5.r = −0.7, p < 0.001 and r = −0.4, p = 0.013 respectively)  . No signvia valve replacement, is reserved for patients who have markedly thickened or calcified valves in whom BMV wouldn't be feasible or in the presence of associated significant mitral incompetence.Rheumatic heart disease represents a significant medical challenge in the developing countries. BMV remains the procedure of choice for patients with rheumatic mitral stenosis who have a favorable valve morphology. This type of intervention is still frequently asked for in the developing countries though it is uncommonly needed in the developed countries owing to the remarkably declined incidence and prevalence of RHD in these regions. Surgical intervention, mostly This study describes the extent, timing and pattern of left ventricular remodeling following BMV. Although, rheumatic heart disease affects primarily heart valves, there is a continuing debate whether the myocardium is affected primarily by the rheumatic process due to molecular mimicry between myosin heavy chain and bacterial proteins or secondary to chronic changes in cardiac output due to valvular disease . FurtherSeveral previous studies described the change in ventricular volumes following BMV. Mohan et al., using angiocardiography in one study  and echoIn the present study, as estimated by CMR, a late significant improvement in LVEF was observed at 1 year following BMV.Using ventriculography, both Mohan et al.  and PamiWe demonstrated a significant improvement in both GLS and GCS at 6 months with a further improvement in both parameters at 1 year.A few previous studies investigated the change in LV deformation following BMV. Sengupta et al. , using TIn our study, the improvement in LV deformation after BMV followed by the late improvement in global ejection fraction suggests that myocardial dysfunction in mitral stenosis is reversible and is probably due to long-standing heamodynamic alteration rather than rheumatic inflammatory process. However, at 1 year both GLS and GCS values remained significantly lower than those of the control group. Though, that might be explained by the presence of a residual mild mitral stenosis, it may also suggest an underlying myocardial factor to be contributing to LV abnormalities. Whether the deformation parameters will continue to increase to reach the levels of the control group at a later stage or will remain as impaired as they are, is a question that needs further investigation.After-load: Increased after-load in MS patients has been described in many previous studies ( studies , 9, 29. Pre-load & pattern of LV filling: In previous studies, LVEDV, used as a surrogate for LV pre-load, has been described to be either reduced, normal (, normal , 30 or e, normal , 32. Abn, normal , 34. The, normal , 34 haveBesides the disturbed loading conditions, it has been debated whether the intrinsic myocardial contractility is normal or impaired in MS patients , 29, 35.In the present study, the absence of late gadolinium enhancement in all MS patients excludes myocardial fibrosis as a contributing factor of LV dysfunction. On the other hand, it took up to 1 year to see a significant change in LVEF after relieving mitral obstruction and this lag may be the time needed for the aforementioned ultra-structural pathological alterations to reverse after correcting the long-standing abnormal loading conditions.The small number of patients included in the study is one of the main limitations. Another limitation is that the recruited patients represented just a subgroup of MS patients where only patients with favourable valve morphology were included. Patients with heavily affected valves were excluded as well as elderly patients and those with any other valvular affection or comorbidities. In clinical practice, MS patients occasionally present with other conditions and associations that might be interfering with the ventricular recovery observed following BMV in this study.This study elucidates LV abnormalities associated with rheumatic MS, proves that the associated LV dysfunction is reversible following BMV and clarifies the time frame of LV recovery. In MS patients who present with significantly impaired LV, physicians may hesitate to dilate the valve lest increasing blood flow may have a detrimental effect on LV. However, this study is reassuring that LV undergoes gradual favourable remodeling following BMV and, in addition, patients with lower baseline myocardial strain values appeared to achieve a higher significant improvement at 1 year.BMV results in continued slow favourable LV remodeling. This strengthens the recent strategy to make this form of treatment available for the very large number of patients who need it worldwide.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Magdi Yacoub Heart Foundation Research Ethical Committee. The patients/participants provided their written informed consent to participate in this study.AS: collecting data and writing the manuscript. KS and SR: conception of the idea, supervising the methodology, and revising the manuscript. WA, MF, and MY: critically revising the manuscript. MH: analysis of the data and statistics. AE: collecting the data. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Japan is one of the most aging societies worldwide. Because older people are highly susceptible to infectious diseases, the characteristics and clinical consequences of bacteremia in this population need clarification.Patients aged ≥ 65 years with positive blood cultures were included in this study conducted between April 1, 2015 and March 31, 2018, and divided into three groups: pre-old (65–74 years), old (75–89 years), and super-old (≥90 years) according to the criteria of the Japanese Society of Geriatrics. They were also classified based on medical exposure: community-acquired (CA), healthcare-associated (HCA), and hospital-onset (HO). Parameters retrieved from medical records were used to compare each group using the chi-square test or Fisher’s exact test; factors related to mortality were identified using multivariate logistic regression analysis after controlling for the confounding effect of baseline characteristics and underlying diseases. The Bonferroni corrected P < 0.05 was deemed to be statistically significant.Escherichia coli bacteremia was most common in super-old patients. While a central line-associated bloodstream infection was more common in pre-old patients, a urinary tract infection was more common in old and super-old patients. The 7-day mortality was 7.4%, 5.8%, and 14.2% in the pre-old, old, and super-old groups, respectively (P = 0.002). The 7-day mortality for CA, HCA, and HO bacteremia was 5.4%, 6.6%, and 9.5%, respectively (P > 0.05). Multivariate logistic regression showed that HO bacteremia  and increasing age  are independent risk factors for 7-day mortality.Overall, 1716 cases of bacteremia were identified in 1415 patients. Of these, 505 cases (29.4%) were found to be due to contamination. Of the 1211 cases without contamination, 397 (32.8%) included pre-old, 658 (54.3%) included old, and 156 (12.9%) included super-old patients. HCA bacteremia increased with age, while HO bacteremia was most common in pre-old patients. Table Comparison of characteristics of bacteremia among the pre-old, old, super-old groups, n (%)The epidemiology of bacteremia differs among different older age groups; thus, these populations should not be treated as a single entity. A careful approach is needed for the optimal management of bacteremia in them.All Authors: No reported disclosures


Ultrasound is one of the most important examinations for clinical diagnosis of cardiovascular diseases. The speed of image movements driven by the frequency of the beating heart is faster than that of other organs. This particularity of echocardiography poses a challenge for sonographers to diagnose accurately. However, artificial intelligence for detection, functional evaluation, and disease diagnosis has gradually become an alternative for accurate diagnosis and treatment using echocardiography. This work discusses the current application of artificial intelligence in echocardiography technology, its limitations, and future development directions. 1. Application of artificial intelligence (AI) in echocardiography is now widely studied, and AI technique has the potential to optimize the diagnostic potential of echocardiography.2. Application of artificial intelligence in echocardiography is important in the following aspects: recognizing the standard section, cardiac cavity automatic segmentation, functional left ventricle assessment, and cardiac disease diagnosis.3. Standardized data collection and image annotation are essential for artificial intelligence in echocardiography. The application of artificial intelligence (AI) technology in cardiovascular imaging has become a research hotspot in recent years, as it may reduce treatment cost and help avoid unnecessary testing . AI techhttps://captionhealth.com/). The development of novel technologies, such as deep learning and neural networks, has effectively improved the efficacy of echocardiography [The integration of echocardiography and AI is not a brand new topic. Earlier cases of integrated application of echocardiography and machine learning can be traced back to 1978 when Fourier analysis was used to evaluate the waveform of anterior mitral leaflets via M-mode ultrasound. Studies have confirmed that this method had a remarkable impact on auxiliary diagnosis of mitral valve prolapse [iography , 11  ultrasound data sets from more than 500 patients and 7,000 videos were gathered from research performed in 2018. A classification model was then constructed using the method of convolutional neural networks by dividing them into seven groups of various cardiac views. The model’s classification accuracy reached 98% . LikewisFunctional evaluation of the left ventricle is one of the most important and routine examination procedures in echocardiographic diagnosis. Functional evaluation indicators of the left ventricle systole include left ventricular ejection fraction (EF), left ventricular volume, left ventricular wall motion function, myocardial contractility and global longitudinal strain (GLS). EF is the most convenient and commonly used indicator for evaluating left ventricular systolic function. Since EF is a ratio when no segmental motion abnormality is present in the ventricular wall, EF can be determined using an M-mode chart by measuring the inside diameter ratio of the left ventricular end diastole to systole. A more precise approach for EF measurement is the biplane Simpson method, especially when segmental motion abnormalities such as myocardial infarction occur in the ventricular wall. The M-mode of certain left ventricular sections cannot represent the motion of the entire left ventricle. At this time, it is necessary to estimate the overall volume using the Simpson method. Regardless of the method employed, evaluations rely on visual observation and manual boundary tracing, while repeatability and accuracy depend on the physician’s experience . The intPrevious research on left ventricular function assessment with assistance of AI technology has been mainly based on automatic segmentation of the left ventricle and endocardial tracking technology . At presThe shape and function of the four chambers of the heart  are observed following the determination of the cardiogram section. If the heart morphology is affected by certain disease-related factors, the standard pressure and volume will change, resulting in cardiac chamber enlargement, compensatory wall thickening, and cardiac remodeling . TherefoLeft ventricular segmentation is popular in the automatic segmentation of the heart chamber. The accurate measurement of ejection fraction and evaluation of the movement in left ventricular myocardium can be achieved by segmenting the left ventricle. Two- and three-dimensional ultrasound methods are both widely used in the assessment of left ventricular segmentation. Compared to 2D ultrasound images, 3D-image resolution is lower. Manual processing and analysis are also extremely time-consuming. Fully automatic left ventricular segmentation based on ultrasound images remains a challenging task due to rapid and large-scale myocardial movements, respiratory interference, inconsistent motion between mitral valve opening and closing, in addition to inherent noise and artifacts in ultrasound imaging. Some methods have been proposed to address the above-mentioned issues. One solution evaluated the ventricular cavity function based on information such as variance to prioritize endocardial boundary refinement , followeCompared to left ventricular segmentation, right ventricular segmentation presents a relatively difficult-to-resolve problem. These problems are related to the characteristics of the right ventricle and its wall, including complex crescent-shaped structure, presence of trabecular myocardium, thinner and weaker right ventricular walls, irregular endocardium shapes and edges on cardiogram images, and relatively poor image quality due to its behind-sternum, location leading to lung gas irruption and shadow of the sternum. These cause blurred ventricular wall echo and even disappearance of entire lateral walls in some images. However, accurate evaluation of right ventricular function is significant for functional analysis of the circulatory system, surgery selection of congenital heart disease (CHD), and prediction and evaluation of heart failure. The precise identification and segmentation of right ventricular ultrasound images can quickly and efficiently capture the diameter, area, and volume of the right ventricle, myocardial thickness, fractional area changes, as well as other indicators to provide more information for auxiliary clinical diagnostics. To overcome these issues, Qin et al. proposed an automatic segmentation framework based on the sparse matrix transform and introduced a wall thickness constraint feature. A positive segmentation result was acquired via detection of endocardium and epicardium at the same time when the lateral walls are blurred . In addiEchocardiographic atrial segmentation has certain application values in minimally invasive interventional treatment of arrhythmia such as cardiac electrophysiology. For example, in radiofrequency ablation treatment of atrial fibrillation, 3D transesophageal echocardiography (3D-TEE) can be utilized to guide cardiac electrophysiological intervention (locating ablation points) in real time. However, there is a prerequisite that the changes in the atrial anatomical structure have to be real-time monitored for precise positioning . AccordiAlthough AI technology can effectively segment atrioventricular structures in echocardiography, recognition and segmentation precision needs to be advanced further due to interference of lung gas, ribs, and artifacts. Algorithm updates, such as multiple iterations, efficient search methods, particle filters, and online collaborative training approaches, combined with deep learning algorithms and multiple dynamic models  will furRoutine echocardiography can visually investigate cardiac valve shapes and activities. Its repeatability is not reliable due to subtle valve structure variations and wide heart motion ranges, as well as the intra- and inter-observer differences in recognizing valve stenosis, prolapse, calcification, and valve insufficiency. The mitral and aortic valves are the objectives of AI technology in cardiac valve evaluation, especially focusing on observation of valve morphology and regurgitation. Similarly, AI technique is helpful in the assessment of valvular heart disease. For example, automatic evaluation software for proximal isovelocity surface area (PISA) of mitral insufficiency can conduct an automatic measurement of mitral valve regurgitant orifice area and regurgitant volume to evaluate the severity of valve regurgitation. PISA for 3D echocardiography has a superior accuracy compared to 2D image analysis software, which has excellent consistency with transesophageal ultrasound and MRI measurements , 33. AnoStructural abnormalities in the congenital aortic valve, senile aortic valve calcification, and rheumatic fever are the common causes of aortic stenosis (AS). The method of aortic valve replacement is crucial for severe AS. Before valve replacement surgery, valve diameter measurement and areas in 2D echocardiography have been manually detected to evaluate the level of valve stenosis and provide a sufficient basis to determine the size of artificial valves. However, because of the dynamic changes in the position of aortic valves in vivo, 2D static image-based assessment is not only subjective but also only reveals the measurement results of one or two frames during the cardiac cycle. Some research studies  have adoCardiomyopathy can be classified into two major categories of primary and secondary cardiomyopathy according to the cause. AI-assisted echocardiographic diagnosis of cardiomyopathy can be carried out via multiple imaging modes, such as 2D ultrasound, M-mode, and color Doppler. Based on accurate wall recognition and ventricular segmentation, automatic measurement of ventricular volume measurement, accurate assessment of cardiac function, and accurate visualization of myocardial movement through speckle tracking technology can be realized. The acquisition of these indicators helps to achieve rapid and precise detection of hypertrophic cardiomyopathy and cardiac amyloidosis. In the latest research, a human-interpretation-free machine learning pipeline based on the combination of ECG and echocardiography had been developed to detect cardiac amyloidosis. Multicenter study had confirmed that the artificial intelligence-enabled fully automated detection model outperformed interpretation by expert cardiologists in the diagnosis of cardiac amyloidosis . On the Coronary heart disease, also known as coronary atherosclerotic heart disease, is one of the most common coronary artery diseases, which is classified as a special type of cardiomyopathy. Echocardiography can assist in its diagnosis by visually observing myocardial movement and changes in cardiac morphology. AI technology can effectively improve subjectivity of conventional echocardiographic examination of coronary heart disease, increase detection systematicity, and help to better distinguish between normal and infarcted myocardial images . For theIn addition to the auxiliary diagnosis of the above-mentioned conventional diseases, AI technology can be applied to classify and recognize intracardiac masses  . For exaIn addition to black box effects, overfitting problems, ethical issues, and other common limitations associated with AI application in the medical field , AI echoRich potential information contained in echocardiograms can be extracted and utilized by AI technology to boost the accuracy of diagnosis. At present, AI technology software is used to examine cardiac ultrasounds, such that the process no longer depends as much on the sonographer’s skills and experience, and with the added benefit of rapid disease diagnosis. The promising expansion of telemedicine with mobile and wireless technologies has produced unprecedented progress in the field of cardiovascular imaging . With th


The pathological changes of myocarditis include degeneration and necrosis of myocardial cells and infiltration of inflammatory cells in the myocardial interstitium, accompanied by obvious myocardial fibrosis. Myocardial fibrosis is a determinant of ventricular remodeling and an important indicator of the classification of clinical risk factors and has an important value in evaluating the prognosis of heart disease. Cardiac magnetic resonance (CMR) is the “gold standard” for evaluating the shape and function of the heart, and it can show the characteristic pathological changes of myocardial tissue. The traditional gadolinium imaging agent delays the enhanced sequence images to visually show the extent of the affected myocardial fibrosis, but it cannot effectively identify small focal fibrosis or widespread diffuse fibrosis. The CMR longitudinal relaxation time quantitative technique can directly measure the relaxation time (T1) determined by the myocardial tissue and does not depend on the signal strength of the reference tissue and can quantitatively analyze the affected myocardium. In this study, the initial and enhanced quantitative imaging techniques of CMR were used to measure the magnetic value of the myocardium in patients with myocarditis, to explore the diagnostic value of myocardial fibrosis, and to analyze the correlation between cardiac fibrosis and cardiac function. Myocardial fibrosis is a determinant of cardiac pathological remodeling caused by various cardiovascular diseases , is the At present, clinical imaging tests commonly used in the clinic include echocardiography, cardiac CT, cardiac magnetic resonance (CMR), cardiovascular angiography, and myocardial radionuclide examination. What are the different examination methods? They have their advantages and values in the morphology, function, diagnosis, and differential diagnosis of myocardial lesions but they also have certain limitations. In recent years, CMR imaging technology has developed more and more rapidly, and clinical applications have become more and more widely used. It has become a routine examination method in cardiovascular centers and large hospitals. CMR has a good temporal and spatial resolution, arbitrary plane imaging, good repeatability, and other advantages. It can play cardiac morphology, function, myocardial tissue characteristics, and myocardial activity in heart disease. The “one-stop” inspection function has a unique value in the cause diagnosis, risk stratification, and prognosis judgment of cardiomyopathy, and it has become the most ideal noninvasive examination method for cardiomyopathy . From a In this study, segments accounted for 5.9%, mostly located in the inferior sidewalls. Previous work summarized the results of the multicenter study and speculated that the myocardial segmental magnetic value difference was not caused by different myocardial composition. The main reason why the MOLLI sequence affects the image quality classification is magnetically sensitive artifacts and respiratory and motion artifacts. The reading of MOLLI adopts an SSP sequence, which can produce magnetic sensitive artifacts similar to the movie sequence. 3.0 T magnetic resonance has higher signal-to-noise ratio and contrast-to-noise ratio, which can provide higher temporal and spatial resolution and shorten the scanning time. However, it is easy to produce a series of problems related to the unevenness of the main magnetic field and the RF field, such as the detuned resonance artifacts of the SSP sequence. But this does not fully reflect the extent of myocardial disease involvement. In this study, there was no statistically significant difference in apical image quality compared with the central and basal parts; and it is indicated that magnetic value can be measured and different sections of left ventricular myocardium can be obtained if the thickness of the apical myocardium is allowed. The magnetic value of the segment completely evaluates the fibrosis of all myocardium.We collected 12 healthy volunteers who underwent CMR magnetic mapping technique scans between January 2015 and December 2016. The scanning sequence includes movie sequence and gadolinium contrast agent delayed enhancement; and magnetic mapping scanning includes more patients (before and after injection contrast agent scanning). The scan adopts the MOLLI sequence. After the scanning is completed, the time is automatically generated. The mentioned method was used to analyze the tapping parameters of the left ventricular myocardium. The mentioned portrayal and measurement are all done by Spin Lite software. Here, we use the Pearson correlation analysis to explore the correlation between each parameter and age. Finally, according to the coronary artery blood supply area, electrical currents were divided into three groups for comparison.According to the position statement of the European Society of Cardiology in 2015 , direct The process of ventricular remodeling eventually leads to direct clinical mention (DCM). The magnetic mapping technique can improve the sensitivity of CMR diagnosis of myocarditis and can be used as an effective means for the assessment of myocarditis condition and efficacy. The fibers of DCM are tandem hyperplasia and eccentric hypertrophy of the heart, the heart is significantly enlarged, the wall thickness is normal or slightly thickened, and the ventricles on both sides are excessively trabeculated. The left ventricular myocardial thickness is increased or thinned due to the enlargement of the heart cavity. Occasionally a subendocardial thrombus can be seen in the heart cavity. DCM has no specific histological manifestations and cardiomyocytes vary in size, cytoplasmic vacuolation, abnormal nuclei, and abnormal chromatin arrangement . AlternaThe degree of myocardial diffuse fibrosis in patients with hypertensive heart disease and left ventricular hypertrophy is higher than that in simple hypertensive heart disease group and normal control group, and an electrical current is positively correlated with left ventricular myocardial mass index. It has a significant correlation with cardiovascular mortality, sudden cardiac death, and heart failure hospitalization rates. It is an independent predictor of cardiovascular death and heart transplant events. But myocardial diffuse fibrosis, lack of fibrosis, and normal myocardium, leading to mild fibrosis lesions, cannot show these problems . Studiesr = 0.85, p=0.01), indicating that the early DCM electrical current can be increased, and the electrical current value can be reflected myocardial collagen deposition. Electrical current can be used as a noninvasive method and quantitative tool for the detection of myocardial fibrosis and can be used to monitor the response and risk stratification of DCM treatment.Magnetic value is negatively correlated with histological fibrosis, similar to the above study results; and magnetic value can be used to noninvasively assess diffuse endocardial fibrosis in patients with cardiomyopathy. Schaefer et al.'s  study shThe tissue characteristics of myocarditis include myocardial edema, hyperemia, and necrosis or fibrosis. The subendocardial biopsy is an important method to diagnose myocarditis, but it may cause complications or adverse consequences, and the tissue intensity can be summarized as in Tapping can be used to quantitatively evaluate the degree of myocardial diffuse fibrosis in patients with hypertension and heart disease, especially the magnetic value and electrical current value. The degree of myocardial diffuse fibrosis in patients with hypertensive heart disease and left ventricular hypertrophy is higher than that in simple hypertensive heart disease group and normal control group, and an electrical current is positively correlated with left ventricular myocardial mass index. Patients with hypertensive heart disease and left ventricular hypertrophy with diastolic dysfunction have higher magnetic and electrical current values than patients with hypertensive heart disease and hypertensive heart disease and left ventricular hypertrophy without cardiac dysfunction, suggesting that the myocardial diffuse interstitial fibers as shown in The myocardium is inhibited earlier than the heart cavity. Not only can acute myocarditis be used for diagnosis but also it reflects the distribution of amyloid, suggesting that the myocardial load of amyloid is an independent prognostic factor. The characteristic enhancement pattern of acute myocarditis can also be distinguished from scars of ischemic cardiomyopathy and myocardial fibrosis of nonischemic cardiomyopathy. The coronary artery's acute myocarditis also tends to develop from normal no enhancement to subendocardial enhancement to transmural enhancement. Therefore, the enhancement pattern changes greatly, and the typical performance occurs in the late stage of the disease, and early lesions can be without acute myocarditis. Many patients with immune light chain amyloidosis (ALCH) have kidney involvement at the same time and cannot perform enhanced scans. The initial magnetic mapping technique does not require contrast agents and can be used for the detection of amyloidosis infiltration degree and efficacy. The electrical current value is significantly higher than that of cardiomyopathy patients and normal control groups, and the distribution of electrical current and acute myocarditis segments is consistent. The value of Natl can diagnose coronary artery. Here we found that the threshold value of AL type is 1020 ms and the diagnostic accuracy is 92%, which has a significant correlation with systolic and diastolic dysfunction. The magnetic value with significantly improved accuracy can reflect the cardiac amyloid load. In the study, the coronary artery's national magnetic value is higher than that of normal volunteers. Our research shows that the magnetic value is about 16% higher than normal and is related to cardiac systolic and diastolic function. Native value is more sensitive to early changes of the disease and prolonged magnetic value, and increased electrical current precedes changes in cardiac hypertrophy. The increase of magnetic value can reflect the severity of the disease and myocardial load. The magnetic value can also be used for treatment monitoring. Studies such as paintings have found that the left ventricular myocardial mass (LVM) of 7 patients who took green tea extract for 12 months decreased, accompanied by a decrease in magnetic value and electrical current, suggesting a decrease in myocardial load of amyloid. Studies have shown that electrical current >0.45 has a significant correlation with mortality (>4.41). Electrical current can be used as a biological indicator for predicting the prognosis of AL.Myocardial fibrosis is a determinant of cardiac pathological remodeling caused by various cardiovascular diseases, is the pathological basis of abnormal cardiac mechanical function and electrical activity, and eventually leads to heart failure and increases patient mortality. A large number of clinical studies have shown that the abnormal expansion of the myocardial extracellular matrix is reversible, so the therapeutic targets of some new research drugs are mainly aimed at fibrosis or myocardial extracellular matrix expansion. Therefore, it is important to detect fibrosis and evaluate the extent of myocardial fibrosis or the degree of expansion of the extracellular matrix. Myocardial tissue includes three components: (1) cellular components, including cardiomyocytes, fibroblasts, epithelial cells, smooth muscle cells; (2) intravascular components, namely, blood; and (3) interstitial space, except for cells and vascular cells. The outer matrix is partially filled. In normal myocardial tissue, myocardial cells are closely packed, and there is little extracellular matrix. The extracellular interstitial space is a complex, mesh-like three-dimensional space surrounded by cardiomyocytes, capillaries, and nerves; it is mainly composed of collagen scaffolds, of which the first situation is 85% and the second is 11%, as shown in The extracellular matrix is damaged under the action of matrix magnetic metalloproteinases (MMPs). The relative levels of tissue inhibitors of metalloproteinases determine the rate of damage. Inflammatory cells and other cytokines also affect the process of myocardial fibrosis. Myocardial fibrosis includes alternative fibrosis and interstitial fibrosis, and the former can be seen in patients with myocardial cell necrosis or myocardial infarction; and the latter can be seen in nonischemic cardiomyopathies, such as sarcoidosis, myocarditis, and chronic renal insufficiency. Interstitial fibrosis can be diffuse, including reactive fibrosis and infiltrating interstitial fibrosis. Reactive fibrosis is seen in aging, high blood pressure, and diabetes. Myocardial fibrosis is a complex process that leads to aggregation/expansion of extracellular matrix and stiff ventricular wall, affects diastolic function, and ultimately damages cardiac contractile function and also affects normal cell activities such as myocardial electrophysiology.An endocardial biopsy is the “gold standard” for diagnosing myocardial fibrosis, but it is an invasive test and may have sampling errors, which limits clinical application. Acute myocarditis is considered to be the “gold standard” for noninvasive detection of myocardial focal fibrosis. The gadolinium contrast agent is an extracellular space contrast agent, which cannot enter the cell through the intact cell membrane. Its function is to shorten the magnetic relaxation time of the tissue. Myocardial fibrosis deposits in extracellular interstitial collagen, causing the body to expand. A gadolinium contrast agent is deposited and concentrated in the extracellular matrix, and the capillary density in the affected area is reduced, and the outflow rate is slowed which shortens the relaxation time of myocardial fibrosis magnetic and is more obvious than the normal myocardial shortening. Delayed scanning adopts magnetic-weighted inversion recovery sequence imaging. The inversion time is artificially set so that the normal myocardial signal is 0 (black), and the fibrotic tissue is a local high signal (showing white), which is in obvious contrast with the surrounding normal tissue. Acute myocarditis is the “gold standard” for imaging scars and fibrosis, especially for focal fibrosis, which has good repeatability. Acute myocarditis of different diseases has different manifestations of myocardial fibrosis, so it can be prompted and identified. However, acute myocarditis also has corresponding problems; and the coincidence rate can be realized into continuous growth, as shown in If the myocardium is diffusely fibrotic, the scanner will mistakenly think that the fibrotic myocardium is normal and incorrectly set the reverse. At the time of transfer, acute myocarditis will display diffuse fibrosis lesions as black, causing its false normalization. However, it will not display diffuse fibrosis, resulting in missed diagnosis, such as diseases with volume load or pressure load overload. There is no abnormal signal delayed enhancement, abnormal heart changes cannot be ruled out. It can be seen that there is no optimal threshold for acute myocarditis on CMR which can well reflect myocardial fibrosis. The signal strength of acute myocarditis cannot accurately identify the type of fibrosis. In patients with renal dysfunction, the gadolinium contrast agent will aggravate the change of renal fibrosis and increase the occurrence of contrast agent nephropathy and cannot be enhanced. Therefore, the quantitative technique based on the inherent properties of the tissue and the direct measurement of the magnetic value and the electrical current technique of extracellular interstitial volume fraction have become research hotspots in recent years. Such techniques can more sensitively detect early and diffuse myocardial fibrosis and improve the diagnostic efficacy of CMR. In October, our working group put forward the consensus of quantitative evaluation of magnetic mapping and extracellular mesenchymal volume fraction .After using inversion recovery (IR) or saturation recovery (SR) pulse sequence scanning, the magnetic mapping parameter map of the heart is generated by each pixel in the magnetic value coding map. In the reverse recovery sequence, the magnetic mapping technology and the improved Look-Locker magnetic mapping technology are commonly used. The Loop-Locker magnetic mapping technology periodically applies a series of low flip angle (<35°) RF pulses to generate gradient echoes. After the magnetization vector is reversed, it uses gradient echoes to read out after each RF pulse. The MR signal quantifies the magnetic value according to the rate of change of the signal amplitude. This sequence can be acquired multiple times under multiple magnetic values, and the imaging speed is fast. The disadvantage is that the gradient echo readout signal causes the inversion recovery curve to change which may lead to inaccurate magnetic measurement and is not suitable for a beating heart. MOLLI technology utilizes balanced steady-state precession (SSP) sequence to read out the signal which can reduce the loss of magnetization vector during reverse recovery and has a smaller impact on the longitudinal magnetization vector recovery curve and can obtain a higher signal-to-noise ratio. From this result, we can use mapping-gating to perform selective image acquisition at the end of diastole, effectively reducing the impact of a heartbeat on image acquisition. The sequence generates a data set that increases the number of samples in the relaxation curve, thereby making the measurement accuracy of magnetic higher in 3.0 T MRI compared to the CT and 1.5 T MRI mappings as shown in MOLLI can collect all tapping data of a single layer of the heart in a breath-holding process. The collection time is less than 200 ms, and there are few motion artifacts. High accuracy, repeatability, and spatial resolution are currently the most commonly used technologies. However, breath-holding time is longer. With heart rate dependence, there are factors such as dependence, magnetization transfer, inversion efficiency, and loss of magnetization vector. The result of SSP reading is the recovery time magnetic, which is lower than the true value of myocardium. Therefore, magnetic mapping needs to be corrected. Common saturation recovery (SR) sequence acquisition method is saturation recovery single-shot acquisition, which is not subject to the measurement within 10 cycles of a heartbeat cycle, and the A-frame measurement is performed within 10 cycles. The SSP sequence read signal is not affected by the loss of the longitudinal magnetization vector and is also not affected by the absolute magnetic value, heart rate, and flip angle. It is more accurate than MOLLI, but the signal noise is lower and the artifacts are more than the latter. Therefore, by this method, the accuracy is reduced.Magnetic mapping technology includes the initial (before enhancement) magnetic mapping and enhanced magnetic mapping. The initial magnetic mapping is to measure the magnetic value of the myocardium by scanning the noninjected contrast agent. This technique is highly repeatable and is not affected by contrast injection. It is suitable for patients with renal insufficiency or contrast allergy. After enhancement, time-mapping is usually injected with a contrast agent at a dose of 0.15–0.220 mm/kg. After 15–20 minutes of injection, an image is collected to measure the myocardial posttime value, but the posttime value is affected by a variety of factors, such as contrast agent dose, concentration, injection rate, and collection time after injection. The increase in the value could be found in the following factors: (1) cell necrosis caused by myocardial injury or myocardial inflammation and (2) myocardial amyloidosis or fibrosis . The decrease in the value is seen in myocardial fat infiltration (such as Anderson-Fabry disease) and myocardial iron deposition disease. However, the magnetic value is dependent on heart rate. Due to the cardiac cycle, the magnetic value in diastole is slightly higher than that in systole, which may be due to the difference in myocardial blood volume between systole and diastole. The magnetic value is also affected by the myocardial segment. Here, we found that the apex is larger than the basal and central native measurements, which may be related to the thinner wall of the apex and the greater proportion of extracellular interstitial. Also, it may be related to the apical image being more susceptible to partial volume effect interference. Moreover, we summarized the results of the multicenter study and speculated that the difference in myocardial segmental magnetic value was not caused by different myocardial composition. But the magnetic field uniformity could be reached into the highest point in a certain time as shown in The magnetic value is affected by the strength of the magnetic field and the accuracy of the measurement method, and these effects may exceed the difference between the normal myocardium and diseased myocardium, making it difficult to directly compare the value under different conditions. Moreover, the magnetic value includes two parts: the interstitial part and cardiomyocytes part. The electrical current of the myocardium reflects the volume fraction of the myocardial tissue that is not occupied by the cells. The electrical current value can be calculated by adjusting the myocardial value and the magnetic value of the myocardium through the blood cell volume, and the electrical current map is generated accordingly. Electrical current measures the space occupied by extracellular interstitium and is correlated with the collagen volume fraction .The typical characteristics of acute myocarditis in HCM patients are patchy or large acute myocarditis between muscles, which are common in the anterior wall, the right ventricular insertion part of the base, the anterior septum, and the area of myocardial hypertrophy, and nonhypertrophic areas appear. In the case of noninvasive disease and edema, electrical current can be used as a biological marker of myocardial fibrosis. The electrical current value is less affected by changes in magnetic field strength. It is affected by the dose of contrast agent, delay time, glomerular filtration rate, hematocrit, and body fat content. Contrast agent injection methods include continuous intravenous infusion and a single bolus injection of contrast agent. From this, we can achieve a dynamic equilibrium state of distribution between plasma and interstitial. We compared two injection methods of normal volunteers, and the difference was not statistically significant. The accuracy of MRI in the first sample is higher than the second value and the third value as shown in The study of the magnetic value before and after infarction found that the initial magnetic mapping can detect myocardial infarction; and the acute myocardial infarction native value (1197 ± 76 ms) is higher than the old myocardial infarction native value (1060 ± 61 ms). Magnetic mapping sensitivity and specificity for the diagnosis of acute myocardial infarction can reach 96% and 91%, which is more sensitive than second mapping. Compared with acute myocardial infarction, the abnormal area of the magnetic value of old myocardial infarction is closer to the range of acute myocarditis display infarction and has a good consistency. However, the abnormal area of magnetic value is larger than the range of acute myocarditis, suggesting that the mapping can be used. Screening for acute myocardial infarction is not suitable for assessing infarct size. Magnetic mapping can quantify the value of myocardial edema of acute myocardial infarction (AMI), reflecting the scope of edema. Magnetic mapping technique combined with acute myocarditis can accurately determine the inversion of myocardial infarction. The value of mapping can also identify the microvascular obstruction. The microvascular area is higher than the distal myocardium but lower than the infarcted myocardium. Magnetic mapping technology can evaluate the degree and severity of the myocardial injury. Here, by using acute myocarditis and mapping as a tool, it was found that native magnetic is significantly related to the severity of the myocardial injury, and magnetic value can predict the recovery of cardiac function. Calculating electrical currents can also accurately diagnose the range of myocardial infarction. The electrical current range of normal myocardium is 24%. In another part, the electrical current of patients with acute myocardial infarction at 1 week was 58.5% ± 7.6%. Our research shows that the electrical current of old myocardial infarction reached 68.5% ± 8.6%. After myocardial infarction, apoptosis is widespread in the infarct area and the noninfarct area. The myocardial cell apoptosis in the noninfarct area and the late ventricular remodeling are mutually causal, leading to the continuous deterioration of cardiac function.The increase of electrical current indirectly suggests that the apoptosis and displacement of the noninfarct area may be related to the mechanism of myocardial remodeling in the noninfarct area. Studies also show that magnetic value in the noninfarct area is heart failure after myocardial infarction. Independent variables are related to cardiac adverse events and death. Although acute myocarditis is still the most important method for detecting acute and old myocardial infarction, magnetic mapping and electrical current can further quantitatively evaluate noninfarct myocardium and the area around the infarct from different angles, which can provide more pathophysiology for the diagnosis and treatment of myocardial infarction information. The new guideline of the European Society of Cardiology in 2014 expanded the definition of hypertrophic cardiomyopathy, which can be regarded as the newfound when the patient has left ventricular wall thickening and increased cardiac load as a nonindependent pathogenic factor. This definition includes not only cardiac muscle. Autosomal dominant genetic diseases caused by mutations in globulin genes also include metabolic and neuromuscular genetic diseases, chromosomal inheritance, and genetic syndromes, as well as aging and amyloidosis. Hypertrophic cardiomyopathy is characterized by ventricular wall hypertrophy, mainly involving the left ventricle. The incidence is about 1/500 and the case fatality rate is nearly 1/1000, which is one of the main causes of sudden death in young adults. Hypertrophic histological cardiomyopathy showed that myocardial cells were hypertrophic and the nuclei were abnormal under the microscope. They were arranged in an irregular, chaotic, herringbone pattern. In asymmetric ventricular septal hypertrophic cardiomyopathy, the increase in myocardial cells also exacerbates ventricular septal hypertrophy. The abnormalities of extracellular interstitial include interstitial fibrosis and alternative fibrosis; in particular, plexiform fibrosis can be seen in the chaotically arranged areas. Interstitial fibrosis can be seen around normal or abnormal cardiomyocytes; alternative fibrosis can extend to areas where cardiomyocytes are missing.Occasionally, there are abnormalities in the intermural coronary arteries, the development of small intermural arteries, the thickening of the intima, and intima with a structural disorder of the intima. Hypertrophic cardiomyopathy fibrosis may be related to two reasons: (1) model caused by abnormal myocardial cells, as well as interstitial and plexiform fibrosis caused by histopathological reactions, and (2) narrowed coronary artery lumen stenosis caused by small abnormalities. Chronic infarction impairs hypertrophic myocardial perfusion and reduces coronary reserve capacity. Previous studies have shown that the interventricular septal area is more common to the intermural arterioles, and the areas with obvious fibrosis are more common than the areas with no or light fibrosis. This result indicates the stage of disease progression. End-stage acute myocarditis patients have a wider range than those who preserve cardiac function. Acute myocarditis is associated with the occurrence of ventricular arrhythmias. Extensive acute myocarditis is associated with an increased risk of sudden cardiac death (SCD) and decreased end-stage systolic function. Acute myocarditis is a risk factor for sudden cardiac death. Acute myocarditis is expected to provide a basis for the risk stratification of SCD and guide implantable cardioverter-defibrillator (ICD) implantation treatment. Histopathologically, the acute myocarditis region reflects alternative fibrosis and end-stage hypertrophic cardiomyopathy fibrosis. Acute myocarditis generally does not appear in the mild fibrosis zone, because the signal in the small fibrosis zone can be completely suppressed. Hypertrophic cardiomyopathy fibrosis is common and the degree of fibrosis of the affected myocardium is different through 48 hypertrophic cardiomyopathy patients and 18 normal controls. Magnetic mapping technique can be used to determine the severity of myocardial fibrosis in hypertrophic cardiomyopathy patients. The evaluation shows that there are different degrees of fibrosis in the surrounding area of acute myocarditis, suggesting that lesions in the early stage of fibrosis can be found. Native magnetic value is valuable for detecting this part of the anomaly without acute myocarditis, and the electrical current value is significantly higher than normal control. We analyzed the results of magnetic mapping's assessment of myocardial fibrosis with the results of high-throughput gene sequencing and endocardial biopsy and found that the mapping values of hypertrophic cardiomyopathy-related gene carriers were significantly shortened after a delay. The decrease of the value is significantly related to the patient's left ventricular diastolic dysfunction, suggesting that the diffuse fibrosis measured by mapping can be used as a powerful tool to link the phenotype and genotype of the patient.This shows that the application of magnetic mapping and electrical current techniques in CMR examination can improve the accuracy of coronary artery diagnosis, quantify amyloid load, distinguish coronary artery types, and predict prognosis. In summary, magnetic mapping technology and electrical current technology can detect early and can quantitatively evaluate the lesions. It has good application prospects in the diagnosis, risk assessment, efficacy, and prognosis evaluation of various myocardial diseases. However, magnetic mapping technology and electrical current technology are affected by many factors. At present, there is a lack of a unified normal reference value. Moreover, large-scale and multicenter research is still required.In the future, electrical current can be used as a biological marker of myocardial fibrosis. The electrical current value is less affected by changes in magnetic field strength. It is affected by the dose of contrast agent, delay time, glomerular filtration rate, hematocrit, and body fat content.


The optimal delivery route to enhance effectiveness of regenerative therapeutics to the human heart is poorly understood. Direct intra-myocardial (IM) injection is the gold standard, however, it is relatively invasive. We thus compared targeted IM against less invasive, catheter-based intra-coronary (IC) delivery to porcine myocardium for the acute retention of nanoparticles using cardiac magnetic resonance (CMR) imaging and viral vector transduction using qPCR.n = 13) by: (1) IM via thoracotomy, (2) catheter-based IC balloon-occlusion (BO) with infusion into the distal left anterior descending (LAD) coronary artery, (3) IC perforated side-wall (SW) infusion into the LAD, or (4) non-selective IC via left main (LM) coronary artery infusion. Hearts were harvested and imaged using at 3T whole-body MRI scanner. In separate Yorkshire swine (n = 13), an adeno-associated virus (AAV) vector was similarly delivered, tissue harvested 4–6 weeks later, and viral DNA quantified from predefined areas at risk  vs. not at risk in a potential mid-LAD infarct model. Results were analyzed using pairwise Student's t-test.Ferumoxytol iron oxide (IO) nanoparticles (5 ml) were administered to Yorkshire swine  while all delivery routes were comparable in the non-risk territory .IM delivery yielded the highest IO retention (16.0 ± 4.6% of left ventricular volume). Of the IC approaches, BO showed the highest IO retention (8.7 ± 2.2% vs. SW = 5.5 ± 4.9% and LM = 0%) and yielded consistent uptake in the porcine distal LAD territory, including the apical septum, LV, and RV. IM delivery was limited to the apex and anterior wall, without septal retention. For the AAV delivery, the BO was most efficient in the at risk territory (Risk: BO = 6.0 × 10Direct IM injection has the highest local retention, while IC delivery with balloon occlusion and distal infusion is the most effective IC delivery technique to target therapeutics to a heart territory most in risk from an infarct. Cardiac gene and stem cell therapies present promising avenues to stimulate myocardial recovery after an infarct or from non-ischemic cardiomyopathies –3. VarioIn the context of gene therapy for heart failure or myocardial infarction (MI), adeno-associated virus (AAV) has been a vector of choice for stable gene delivery to cardiomyocytes . AAV vecin-vivo delivery of: (1) iron oxide nanoparticles 25 nm in size  (n = 13) or (2) adeno-associated virus serotype 9 (AAV) (n = 13) (ex-vivo cardiac magnetic resonance imaging (CMR) tracking of IO, or for assessment of AAV vector transduction. In order to assess the degree of myocardial injury specific to a delivery technique, high sensitivity troponin I  levels in blood were assessed immediately after induction of anesthesia for baseline levels and 15 min after completion of IO delivery, immediately prior to the heart harvest. The relatively short 15 min post-IO delivery time point for troponin level assessment was selected to minimize IO washout from the heart. The AAV-injected animals were not included in the troponin analysis to avoid confounding results from an MI injury prior to AAV delivery. We favored troponin I based on previous studies of biomarkers of myocardial ischemia in porcine models . Myocardial therapeutic delivery techniques were compared in Yorkshire swine  in two study arms, by tracking (n = 13) . AAV expFour swine in the IO study arm and six swine in the AAV study arm underwent IM injection . For thiA surgical cutdown was performed through a vertical paratracheal incision and the common carotid artery dissected free over several centimeters and encircled with a vessel loop. Heparin 200–300 units/kg was administered intravenously. The artery was then accessed with a 21-gauge micropuncture introducer needle and 5-french micropuncture catheter was advanced over a wire, which was subsequently upsized to a 6-french vascular sheath.Three swine underwent LM infusion in both the IO and AAV study arms . LM deliIn both the IO and AAV study arms, four swine underwent delivery with the BO approach . BO deliTwo swine had infusion via the SW technique in the IO study arm, but this technique was not utilized in the AAV arm . The SW All hearts were harvested via sternotomy within 15 min of IO delivery under deep anesthesia, after systemic administration of a high potassium chloride (KCl) solution to induce cardiac asystole. CMR imaging was performed immediately following harvest with fresh, unpreserved hearts. The harvested hearts were suspended in a container and the ventricles were filled with an MRI-inert fluid . This allows the heart to maintain a diastolic shape with no signal from inside the ventricular chambers. The container was positioned in the center of a 64-channel head and neck coil and imaged using a 3T whole-body MRI scanner . A whole-heart 3D inversion recovery (IR) sequence was obtained using the following parameters: TE/TR/flip angle: 2.03 ms/4.38 ms/15°, voxel size: 0.5 × 0.5 × 1.0 mm, and inversion time: 300 ms . Scan time for each acquisition was 10–12 min.The 3D whole-heart (IR) sequence was used to determine the presence and location of iron deposits within the myocardium. After reconstructing the 3D heart volume in a short-axis orientation, the left ventricle (LV) was divided into anterior, septal, lateral, and inferior regions. The anterior and inferior RV insertion sites were used to define the intraventricular septum. The posterior segment was defined as encompassing the inferior wall adjacent to the posterior papillary muscle, while the anterior wall was defined from the anterior insertion of the RV wall to the anterolateral papillary muscle. The lateral wall was defined as the section between the anterior and posterior papillary muscles. Within each section, iron accumulation  were manually planimetered. The volume of iron accumulation was calculated as a percent of overall LV volume and as percent of volume within each specific LV region.AAV9 production followed the same standardized approach for all experiments. Suspension-adapted HEK293 cells were cultured in F17 Expression Medium (Thermo Fisher A1383501) supplemented with 0.1% Pluronic F-68 (Millipore Sigma K4894), 4mM GlutaMAX (Thermo Fisher 35050061) and 1% penicillin-streptomycin (P-S) (Thermo Fisher 15070063) in a ReadyToProcess Wave 25 Rocker bioreactor (Cytiva 28988000).rep-cap plasmid (AAV9 capsid variant), an adenoviral helper plasmid (pXX680), and a transgene packaging cassette, flanked by AAV2 inverted terminal repeat (ITR) sequences. Media supernatant was harvested 5–6 days post-transfection and subjected to tangential flow filtration (Repligen S02-E100-10-N) followed by PEG precipitation. Viral vectors were purified via iodixanol density gradient ultracentrifugation, followed by Dulbecco's phosphate-buffered saline (dPBS) containing 0.001% Pluronic-F68 buffer exchange using Pierce Protein Concentrator 100 kDa molecular weight cut-off (MWCO) spin columns (Thermo Fisher 88533). Titers of purified virus preparations were determined by quantitative PCR with primers amplifying the AAV2 ITR regions  .Recombinant AAV vectors were produced using a triple plasmid transfection method consisting of an AAV 4 HEK293 cells in 50 μL of medium was then added to each well, and the plates were incubated in 5% CO2 at 37°C for 48 h. Cells were subsequently lysed with 25 μL of 1× passive lysis buffer (Promega) for 30 min at room temperature. Luciferase activity was measured on a Victor 3 multilabel plate reader (PerkinElmer) immediately after the addition of 25 μL of luciferin (Promega). All readouts were normalized to controls with no serum treatment. The ssCBA-Luc AAV was only used for the neutralizing antibody screen and not for in vivo delivery.Prior to vector delivery, all animals in the AAV study arm were screened for neutralizing antibodies using previously described methods . Specifi13 to 1 × 1014 of viral particles (vp) per animal. At 4–6 weeks post-AAV delivery, hearts were harvested immediately following cardiac arrest with systemic KCl administration and both coronary arteries were perfused with 500 mL of heparinized cold cardioplegic solution  using a 7-french catheter. Biopsies were systematically taken from 16 pre-specified locations  grouping the biopsy locations into different regions of the heart including the LV lateral wall, LV anterior wall, LV apex, and RV.Porcine models of myocardial infarction are commonly utilized to model acute injury as well as ischemic cardiomyopathy and study candidate therapeutics. The left anterior descending (LAD) coronary artery is the most commonly utilized target for such models, including parallel studies at our institution, due to fairly consistent perfusion territory and ease of exposure for surgical ligation or ease of access via coronary angioplasty techniques . With a t-tests with Tukey adjustment for multiple comparisons. All statistics were performed using R Statistical Software  and Prism .For descriptive analyses, continuous variables were presented as mean ± standard deviation or median [interquartile range] depending upon the normality of distribution. Comparisons among the various delivery techniques were assessed with a global analysis of variance followed by pairwise Student's n = 4), BO (n = 4), SW (n = 2), and direct LM (n = 3) techniques. On 3D CMR analysis, overall mean percent left ventricular volume of IO was 8.4 ± 6.8% with the various delivery approaches. The IM approach yielded significantly higher retention of IO compared to the combined IC approaches  (Delivery of 5 ml of IO nanoparticles was performed in 13 swine with the IM (= 0.008) . Within = 0.008) . Assessi= 0.008) , IM deli= 0.008) . Quantit= 0.008)  confirmep = 0.03) (p = 0.11).Based on pre- and post-operative troponin I levels in the IO substudy animals, IM delivery resulted in significantly greater myocardial injury with median increase in troponin I of 12,200 ng/L  compared to 158 ng/L [IQR 0–201] with IC delivery ( = 0.03) . The two = 0.03)  and the n = 6), BO (n = 4), and LM (n = 3) techniques in a survival model. The BO approach achieved the highest tissue transduction of virus in the targeted territories, particularly the LV apex , although these differences did not reach statistical significance. All three techniques resulted in relatively lower transduction in non-targeted regions, such as the lateral LV free wall supplied by the left circumflex artery . Dividing the heart into “At Risk” and “Non-Risk” territories, the BO approach yielded the highest uptake in the “At Risk” region  vector was delivered via IM , using CMR and long-term vector expression following AAV injection/infusion using qPCR. We showed that direct IM injection resulted in the highest volume retention of IO nanoparticles in the heart, while targeted BO approach was the most effective among the catheter-based approaches. Compared to IM injection, the less invasive catheter-based IC delivery resulted in improved viral uptake throughout the vascular territory of interest  and significantly less myocardial injury measured by post-operative troponin I levels. Regarding the general agreement between acute IO retention and long-term AAV expression, initial distribution of delivered therapeutics throughout the heart is expected to be an important determinant of long-term tissue targeting and therapeutic outcomes.A number of variables must be considered when assessing the benefits and limitations of studied cardiac delivery techniques. For example, IM delivery suffers from non-uniform distribution of therapeutics near the injection sites, as shown by White et al. who demonstrated small heterogeneous pockets of AAV expression at myocardial depth corresponding to needle length . IC deliThe differential regenerative potential of various regions of myocardium post-infarct highlights the importance of targeted therapeutic delivery. Prior studies have identified the infarct border zone (BZ), the perfused but hypocontractile region bordering the infarct, as the transcriptomically distinct region in zebrafish, mice, pigs, and humans –25. ThisA thoracotomy approach to deliver therapeutics via IM injection , 30 i.e–33. MoreThis study has multiple limitations inherent to the study design. First, while animals were of similar weights and ages, the physical heart size may be variable, which could affect the measurements of percent of LV volume occupied on CMR. Second, as the iron oxide studies were acute, long-term implications of direct needle injury during IM injection could not be assessed. Third, since the AAV experiments involved delivery of multiple target genes, beyond the scope of this study, the analysis of data presented was limited to the efficacy of viral transduction in different heart regions, rather than expression of delivered transgene. Finally, while IO and AAV are nearly identical in size (25 nm), uptake of these molecules differ in the AAV is receptor dependent. Thus, mechanisms beyond just delivery technique may play a role in uptake through the endothelium into the interstitial space.In summary, with ongoing evolution of transcatheter approaches for coronary arterial and valvular diseases, it is essential to establish techniques that can deliver therapeutics without (re)entering the chest and targeted to a specific region of interest. In this study, despite lower retention than IM injection, less invasive IC techniques, particularly paired with proximal balloon occlusion to limit competitive flow, resulted in efficient uptake of both AAV and similarly sized nanoparticles. BO also allowed for delivery to the entire vascular bed of interest and regions of the heart not easily reached via epicardial IM injection. Further investigations in large animal models to understand the implications of each technique for AAV-based therapeutic outcomes are warranted.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The animal study was reviewed and approved by Duke University Institutional Animal Care and Use Committee (IACUC).AV, SD, and AW: study design, study execution, data analysis, and manuscript drafting and revision. DW: study design, study execution, and manuscript drafting and revision. YC and DB: study design, study execution, and manuscript revision. RY, MB, GD, AA, and KP: study design and manuscript revision. NB: study design, study execution, data analysis, and manuscript revision. All authors contributed to the article and approved the submitted version.This work was supported by Translating Duke Health Initiative from Duke University and National Institutes of Health grants U01HL134764 to NB and 5T32HL069749 to AV.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Background: The cardiovascular effects of SARS-CoV-2 in elite athletes are still a matter of debate. Accordingly, we sought to perform a comprehensive echocardiographic characterization of post-COVID athletes by comparing them to a non-COVID athlete cohort.Methods: 107 elite athletes with COVID-19 were prospectively enrolled  107 healthy athletes were selected as a control group using propensity score matching (N-CA). All athletes underwent 2D and 3D echocardiography. Left (LV) and right ventricular (RV) end-diastolic volumes (EDVi) and ejection fractions (EF) were quantified. To characterize LV longitudinal deformation, 2D global longitudinal strain (GLS) and the ratio of free wall vs. septal longitudinal strain (FWLS/SLS) were also measured. To describe septal flattening (SF—frequently seen in P-CA), LV eccentricity index (EI) was calculated.Results: P-CA and N-CA athletes had comparable LV and RVEDVi . P-CA had significantly higher LVEF , while LVGLS values did not differ between P-CA and N-CA (−19.0 ± 1.9 vs. −18.8 ± 2.2%). EI was significantly higher in P-CA , which was attributable to a distinct subgroup of P-CA with a prominent SF , further provoked by inspiration. In this subgroup, the EI was markedly higher compared to the rest of the P-CA , LVEDVi was also significantly higher , while RVEDVi did not differ (82 ± 16 vs. 78 ± 15mL/m2). Moreover, the FWLS/SLS ratio was significantly lower in the SF subgroup . P-CA with SF experienced symptoms less frequently .Conclusions: Elite athletes following COVID-19 showed distinct morphological and functional cardiac changes compared to a propensity score-matched control athlete group. These results are mainly driven by a subgroup, which presented with some echocardiographic features characteristic of constrictive pericarditis. The COVID-19 pandemic represents an unprecedented challenge to the healthcare systems worldwide with still increasing patient numbers. While the infection was initially thought to be affecting mainly the respiratory tract, current evidence suggests that the cardiovascular consequences of COVID-19 are not negligible , 3.Fortunately, COVID-19 is often asymptomatic or associated with only mild symptoms, especially in the young . Still, Elite athletes are a distinguished group of young individuals as a relatively high proportion of them underwent (or will undergo) the infection. This is attributable to their high-risk profile: a young community with frequent social interactions; the majority of sport disciplines include direct physical contact; and wearing a mask during training sessions or competitions is rarely a realistic expectation . While tAccordingly, we sought to perform a comprehensive echocardiographic characterization of post-COVID athletes and compare them to a propensity score (PS)-matched healthy athlete cohort.n = 5) and athletes who suspended regular training in the preceding 6 months before their SARS-CoV-2 infection (n = 2) were excluded.We consecutively enrolled elite athletes undergoing “return to play” examinations between September and December 2020 at our Center's Sports Cardiology Department . The study protocol complies with the Declaration of Helsinki, and participants gave written informed consent to every procedure. SARS-CoV-2 infection was diagnosed by real-time polymerase chain reaction (rt-PCR) or by serum immunoglobulin G (IgG) antibody titer measurement. All athletes were officially released from quarantine defined by having two negative rt-PCR assays of nasopharyngeal swab specimens following the infection and/or passing the appropriate quarantine period (10 or 14 days depending on the time of enrollment). All of the athletes completed a questionnaire regarding the nature and duration of their SARS-CoV-2 infection, based on the recommendation of the National Institute of Health . DetaileTo enable the appropriate pairwise comparison of COVID vs. non-COVID athletes, PS-matching was performed with the optimal pair matching algorithm . Our ins*posterior wall thickness/LV end-diastolic internal diameter. LV diastolic eccentricity index was measured from parasternal short-axis view at the level of the papillary muscles, defined as the ratio of the distances between the anterior-to-posterior wall and the septal-to-lateral wall in end-diastole. Left- and right atrial volumes were measured using the Simpson method and were indexed to BSA. LV diastolic inflow by pulsed-wave Doppler at the level of the mitral valve coaptation was obtained to determine early (E) and late diastolic (A) peak velocities, their ratio, and E-wave deceleration time. Pulsed-wave tissue Doppler imaging (TDI) was used to measure systolic (s′), early (e′), and late diastolic (a′) velocities at the mitral lateral and medial annuli. The ratio of E-wave velocity to averaged e′ velocities of the mitral medial and lateral annuli was calculated, serving as an estimate of LV filling pressures. Tricuspid annular plane systolic excursion (TAPSE) was measured by M-mode as the peak longitudinal excursion of the tricuspid annulus on an apical four-chamber view. Inferior vena cava (IVC) diameters estimated right atrial pressure (RAP), pulmonary arterial systolic pressure (PASP), diastolic pressure (PADP), mean pressure (PAMP), and also pulmonary vascular resistance (PVR) were quantified according to the current echocardiographic recommendations . Cardiac chambers were quantified according to current guidelines . Left vendations . The preECG-gated, LV-focused apical long axis, four- and two-chamber view loops targeting a frame rate over 50 FPS were obtained for further analysis. STE was performed by a single expert operator (B.L.) blinded to the study groups using dedicated semi-automatic software . The software automatically detects the myocardial region of interest (ROI) of the given acquisition and tracks its motion throughout the cardiac cycle. If necessary, the ROI was adjusted manually in order to provide adequate tracking. Segments with poor tracking quality (driven by the software's recommendation) were excluded from the analysis; however, subjects with three or more excluded segments were not included in the study (none). The software automatically calculates global longitudinal strain (GLS) and segmental longitudinal strain (LS) values as well. By averaging the segmental data of the free wall  and septal  regions, we have quantified FWLS and SLS, respectively.LV- and RV-focused ECG-gated full volume 3D datasets were obtained from apical four-chamber view using multi-beat reconstruction from 4 cardiac cycles. Offline analyses of these datasets focused on the LV and RV were performed by the same expert, blinded operator using conventionally available software packages . The algorithm automatically generates LV and RV endocardial contours, which were manually corrected on multiple short- and long-axis planes throughout the entire cardiac cycle. We determined the LV and RV end-diastolic volume index (EDVi), end-systolic volume index (ESVi), and stroke volume index (SVi) normalized to BSA. To quantify global ventricular function, LV and RV ejection fractions (EF) were also calculated.t-test, in case of normal distribution, or a Mann-Whitney U test, in case of non-normal distribution, was performed to compare the continuous variables of the study groups. Fisher's exact test was used to compare the incidence of symptoms between groups. A p < 0.05 was used as the criterion for statistical significance.All values are expressed as mean ± standard deviation, or median and interquartile range (IQR). The distribution of the variables was assessed by the Shapiro-Wilk normality test. An unpaired two-sided Student's Intra- and interobserver variability of the most relevant parameters were also assessed. The operator of the first measurements (B.L.) and a second expert reader (A.F.), both blinded to the study groups, repeated the measurements in a randomly chosen subset of 5–5 athletes from each group. Lin's concordance correlation coefficient and coefficient of variation were calculated.n = 37, ice hockey n = 26, water polo n = 26, basketball n = 12, speedskating n = 2, other n = 4) were included in the current analysis. Athletes were asymptomatic at the time of examination with the exception of the loss of taste and/or smell in a handful of cases (n = 12), as these symptoms frequently exceed the period of active infection . This finding was mainly driven by a subgroup  of post-COVID athletes, in which an early-diastolic septal flattening (SF) was present consistently throughout the entire echocardiographic examination on multiple views, showing an inspiratory enhancement . Post-COVID athletes with SF and without SF did not differ in terms of the number of symptomatic days , the time between the onset of symptoms and the examination , or the time elapsed between the first positive PCR or IgG and the examination . The incidence of fever , coughing , headache , and loss of smell and/or taste  were also comparable between the athlete groups. Interestingly, chest pain  and fatigue  were reported more frequently in post-COVID athletes without SF  pericardial effusion was more frequent in the SF subgroup of post-COVID athletes compared to the corresponding subset of PS-matched non-COVID athletes . Regarding 3D echocardiographic measures, post-COVID athletes with SF had significantly higher LV EDVi and LV ESVi compared to post-COVID athletes without SF, while RV morphological measures along with LV and RV EF were similar (n = 5). Notably, no myopericardial involvement was detected by cMR in these cases. Detailed case reports are presented in Regarding basic echocardiographic measures, post-COVID athletes with SF showed significantly higher E/A ratio, while RAP and PADP were also found to be significantly higher compared to post-COVID athletes without SF . LV dias similar . 2D LV G similar . During Intra- and interobserver variability of the key echocardiographic parameters showed good intra- and interreader agreements .Our study is the first to investigate a relatively high number of European elite athletes who underwent mild COVID-19, while also comparing them to a PS-matched healthy athlete group using a comprehensive echocardiographic approach. We have shown that post-COVID athletes show distinct changes in cardiac morphology and function compared to matched non-COVID athletes. Of note, the vast majority of these alterations was attributable to a subpopulation of athletes in whom an inspiration-enhanced early diastolic SF could be detected. In these athletes, the E/A ratio of mitral inflow, the 3D echocardiography-derived LV volumes were significantly higher, along with a significantly lower FWLS/SLS ratio.The earliest reports from China already mentioned the high prevalence of elevated cardiac necroenzymes and the commonly deteriorated LV functional measures in COVID-19 patients . With thIn our post-COVID population, LV wall thicknesses and RWT were significantly lower compared to the matched control athletes. These findings may correspond to the effects of short-term detraining: LV wall thicknesses are known to decrease even after a few weeks of suspended athletic activity along with unaltered ventricular volumes , 22. RegIn a subpopulation of our post-COVID elite athletes, an early diastolic SF was detected with inspiratory enhancement, commonly resulting in marked LV eccentricity . This phCOVID-19 is also known to affect the pulmonary vasculature . HoweverThe aforementioned study of Brito et al. reported a surprisingly high prevalence of pericardial involvement in their study enrolling student athletes . While aInterestingly, SF was more common in athletes with generally fewer symptoms. This corresponds to previous large-scale cMR data demonstrating that all athletes with confirmed inflammatory heart disease were only minimally symptomatic . MoreoveHowever, it is important to mention that in those cases where cMR was also performed, no signs of pericardial inflammation or constriction were detected. Considering that the main body of data about the reverse remodeling after abrupted training is derived from small sample studies of the early 90's, it is plausible that a temporary change in the pericardial constraint is a benign phenomenon of athletic detraining (HIV). Hemodynamic overload is proved to induce not only myocardial, but pericardial remodeling as well (HIV). Therefore, it is suspected that intense regular exercise may also induce changes of the pericardial structure. While myocardial deconditioning is known to take place over the course of a few weeks of abrupted training regime, the altered characteristics of the pericardium may persist for a longer time, resulting in temporary changes of the pericardial constraint.The current Sports Cardiology and Exercise Guideline of the European Society of Cardiology recommends at least 30 days of suspended training in the case of pericarditis, however, in the absence of a proven inflammatory process the clinical implications of these findings are hard to judge (HIV).In the case of persistent constriction-like changes in the SF post-COVID group, an impaired peak exercise capacity has high possibility (HIV)., Follow-up of athletes and further research are urged to explain the appearance and the potential clinical consequences of the constriction-like echocardiographic findings in the context of the athlete's heart.Our study carries limitations that have to be acknowledged for adequate interpretation. First, our case number is limited. Nevertheless, the number of subjects is considered to be relatively high as compared to current COVID-19-related data in athletes. The population has a male predominance; therefore, the study was not powered to examine the role of gender differences. In the post-COVID athlete group, echocardiographic loops prior to the SARS-CoV-2 infection were not available. Therefore, PS-matching was used to provide a matched control athlete group. The observed changes were often subtle and only statistically significant. The most common causes of SF are pulmonary hypertension and constrictive pericarditis, and the gold-standard evaluation method for both these diseases is still right (and left-) heart catheterization . For obvOur results suggest that even mild SARS-CoV-2 infection may significantly affect cardiac morphology and function in elite athletes. The observed alterations are mainly attributable to a subgroup of athletes, in whom some features of pericardial constriction could be detected, such as pericardial effusion, early diastolic SF with inspiratory enhancement, and STE-derived “hot septum” sign. Interestingly, these athletes seemed to experience fewer symptoms during the course of the infection. Considering that current guidelines usually propose a more thorough return to play examinations in symptomatic athletes only, our data is especially alarming, as many of our athletes presented with SF would not have been eligible for a detailed assessment . The patThe original contributions presented in the study are included in the article/The studies involving human participants were reviewed and approved by National Public Health Center; No: ETT TUKEB IV/10282-1/2020/EKU. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.BL, MT, AF, MB, and AK contributed to the conception of the study design. BL, HV, LS, NS, EC, OK, MB, AK, ZG, and AS performed the measurents. BL, MT, AF, ZL, LS, and EC managed the database. BL and MT perfomed the statistical analysis. BL, MB and AK wrote the draft of the manuscript. MT, AF, HV, LS, NS, EC, OK, AS, and MB reviewed it. BL, MT, and MB prepared the figures. All authors contributed to the article and approved the submitted version.Project no. NVKP_16-1-2016-0017  has been implemented with the support provided from the National Research, Development and Innovation Fund of Hungary, financed under the NVKP_16 funding scheme. This research was financed by the Thematic Excellence Programme (2020-4.1.1.-TKP2020) of the Ministry for Innovation and Technology in Hungary, within the framework of the Therapeutic Development and Bioimaging Thematic Programmes of the Semmelweis University and also by the New National Excellence Program of the Ministry of Human Capacities . This project was also supported by a grant from the National Research, Development and Innovation Office (NKFIH) of Hungary (K135076 to BM). AK was supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences. This project was supported by a grant from the National Research, Development and Innovation Office (NKFIH) of Hungary (2020-1.1.6-JÖVŐ-2021-00013).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.