Despite advancing technology, right heart failure after left ventricular assist device implantation remains a significant source of morbidity and mortality. With the UNOS allocation policy change, a larger proportion of patients proceeding to LVAD are destination therapy and consist of an overall sicker population. Thus, a comprehensive understanding of right heart failure is critical for ensuring the ongoing success of durable LVADs. The purpose of this review is to describe the effect of LVAD implantation on right heart function, review the diagnostic and predictive criteria related to right heart failure, and discuss the current evidence for management and treatment of post-LVAD right heart failure. Durable left ventricular assist device (LVAD) technology has advanced considerably over the past 20 years, such that current third-generation devices  have an event-free survival rate of nearly 80% at two years ,2. HowevHistorically, implantable LVADs were utilized for shorter periods of time while patients awaited availability of a donor organ . Since the UNOS allocation policy changed in 2018, higher acuity patients tend to proceed directly to transplant, and stable LVAD patients have significantly longer wait times ,12. As aWe aimed to describe the interplay of right ventricular function with LVADs; review the diagnostic criteria as well as clinical, imaging, and hemodynamic factors related to RHF; discuss the current evidence for management and treatment strategies to handle this challenging entity.The right ventricle (RV) is distinct from its left ventricular (LV) counterpart as a thin-walled and heavily trabeculated triangular structure. Within the RV sits the crista supraventricularis, a muscle bridge dividing the tricuspid valve inflow from the pulmonic valve outflow. The crista supraventricularis plays a crucial anatomic role in RV function, as its muscle fibers interlace with the interventricular septum  and the RV free wall; during systole it acts to narrow the tricuspid orifice and contract the RV free wall towards the interventricular septum ,14.The purpose of the RV is threefold: (1) to preserve low systemic venous pressures to avoid liver and kidney dysfunction, (2) to maintain forward momentum of blood flow to the pulmonary circulation, and (3) to provide oxygenated preload to the left heart in order to maintain adequate perfusion ,15,16. IThe RV is influenced by multiple factors including systemic venous return (preload), pulmonary resistance (afterload), and intrinsic contractility. Under optimal conditions, the RV cardiac output approximates that of the LV; this is also affected by ventricular interdependence, with the LV contributing to RV output via the septum. Importantly, RV function is sensitive to afterload, which can be defined as the RV wall stress during systole as estimated by a combination of attributes  during systolic ejection ,18. As aLVAD implantation results in an immediate and dramatic shift in hemodynamics and physiology. As the LVAD decompresses the LV, there is an improvement in upstream pressures  and mitral regurgitation. This results in decreased RV afterload due to the improved LV filling pressures and the theoretical expectation of improved RV function. However, there are multiple forces at play that may, in fact, lead to RV dysfunction and subsequent failure . While cIntraoperative factors also have a significant impact on RV function and particularly early RHF . CardiopStudies analyzing the effects of LVAD implantation on RV hemodynamics have demonstrated that pulmonary vascular resistance (PVR) decreases dramatically in the first three months post-VAD implantation ,27. ThisDefinitions for post-LVAD right heart failure vary significantly in clinical criteria and time frame but generally include the need for intravenous inotropes, pulmonary vasodilators, and/or right-sided circulatory support ,32,33,34In 2014, the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) proposed a more granular definition of post-LVAD RHF using hemodynamics and clinical findings . RHF wasLate RHF is even less well defined, as many definitions combine early and late RHF into one category. However, late RHF is generally determined to occur after initial hospital discharge ,24 Tabl. Kormos The lack of standardized definitions for early and late RHF is problematic as reproducibility is limited, valid comparisons of incidence rates are challenging, and prediction models demonstrate significant variability . UtilizaNumerous risk scores and predictive models have been created to better identify patients at risk for post-LVAD RHF. The goals of these models are to gain insight into patient prognosis, improve risk stratification and patient selection, and allow for implementation of treatment strategies to avoid poor outcomes ,22,36. MMany existing risk score models were derived from single-center cohorts ,31,32,33There are a host of clinical characteristics, laboratory values, imaging data, and hemodynamic parameters associated with post-LVAD RHF . In a laEchocardiography is an enticing modality to determine both accurate preoperative RV function and factors that may predict post-LVAD RHF. However, technical challenges , poor reproducibility, and low interobserver correlation make reliance on echocardiography more challenging. Interestingly, only the Penn RVAD, CRITT, and EUROMACS-RHF risk scores utilize preoperative RV dysfunction on echocardiography in their models ,30,33. M−2 [Invasive hemodynamics are crucial in the assessment of RV function and proper risk stratification prior to LVAD implantation. A large study of 475 LVAD patients showed that elevated central venous pressure (CVP) was an independent predictor of postoperative RHF . Elevate−2 . Notably−2 , though −2 .Risk factors for late RHF differ slightly from those mentioned above. Two large single-center studies examined predictors for late RHF and found that typical clinical characteristics for early RHF, such as intra-aortic balloon pump use, mechanical ventilatory use, or use of vasopressors or inotropic support, were, in fact, not predictive of late RHF. Pump speed and even the occurrence of early RHF were not predictors. Rich et al. found that elevated preoperative BUN and increased CVP:PCWP ratio were independent predictors of late RHF, while Takeda et al. found that diabetes, BMI > 29, and elevated BUN were univariate predictors for late RHF ,10.Management of RHF preoperatively should utilize a multifaceted approach aimed at addressing RV preload, afterload, and contractility. RV preload should be optimized aggressively, understanding that the patient will likely undergo multiple blood product transfusions intraoperatively. While there is no standard CVP target used, ideally the CVP goal should be <15 mmHg given that a CVP > 15 mmHg is associated with post-LVAD early RHF ,49. HemoMitigating causes of elevated PVR is also an important goal given that the RV is particularly sensitive to afterload. Use of inhaled pulmonary vasodilators like epoprostenol and nitric oxide are advantageous in selected patients as it avoids systemic hypotension and has beneficial short-term effects in lowering PVR and improving RV cardiac output ,52. SildIt is also crucial to enhance forward flow and augment RV perfusion. If inotropes are used, milrinone and dobutamine are the preferred agents given their combined inotropic and vasodilator properties. Milrinone results in both pulmonary and systemic vasodilation with increased myocardial inotropy, ultimately serving to reduce both RV and LV end-diastolic pressures; thus, milrinone is the preferred agent over dobutamine in appropriate situations . HoweverThere are a number of perioperative factors that can impact RV function postoperatively including cardiopulmonary bypass time, perioperative bleeding, volume loading with blood product transfusions, interventricular septal shift once the LVAD is implanted, and disruption or injury of blood flow to the right coronary artery  ,24,55. MMedian sternotomy has been the standard surgical approach for LVAD implantation, with obvious advantages including full visualization and ability to perform other interventions and place central RV support if necessary. An alternative lateral thoracotomy approach was first studied in the HeartWare LVAD, and showed that it was a safe and effective alternative in selected patients . AdvantaThere is lack of consensus regarding the utility and efficacy of concurrent tricuspid valve repair (TVr) for functional tricuspid regurgitation. Early observational studies suggested that concomitant TVr improved early clinical outcomes, reduced incidence of early RHF, and was a durable adjuvant procedure ,59,60. H2, and ensure adequate LV unloading via the device [Recognition of RHF in the immediate postoperative period can be tricky, as the clinical presentation mimics that of cardiac tamponade. Oftentimes, patients return from the operating room on multiple vasopressors for vasoplegia-mediated hypotension, and echocardiography may not be informative given technical limitations in a postoperative patient. Ultimately, there are five main aspects to consider when managing the RV postoperatively: (1) preload optimization, (2) inotropy, (3) chronotropy, (4) pulmonary vasodilation and management of the PVR, and (5) optimization of the systemic mean arterial pressure and pump speed to support the septum. Goals are to support the patient to preserve euvolemia with an approximate CVP < 12 mmHg, maintain perfusion with a mean arterial pressure > 70 mmHg and cardiac index > 2.2 L/min/me device ,24. AdjuIn contrast to outcomes associated with preoperative PDE5i use, postoperative PDE5i use may in fact be beneficial with lower all-cause mortality and fewer ischemic strokes in an observational study of patients implanted with centrifugal flow LVADs; however, the mechanism by which this occurs is unclear . Furtherpreoperative patient selection may help to identify patients who would benefit from planned or early institution of biventricular support.Early consideration and institution of mechanical RV support confers survival benefit and helps to prevent potentially irreversible multiorgan failure ,69,70. IOptions for mechanical RV support include both temporary and intermediate devices ,71,72. TIntermediate options for mechanical RV support involve surgical implantation of an RVAD with central cannulation of the RA or RV for venous inflow and the PA for arterial outflow. The cannulas are connected to centrifugal flow pumps such as CentriMag Pump (Abbott), RotaFlow (Macquet CP), and TandemHeart (LivaNova). Unfortunately, long-term options for durable RVADs do not exist and remain a thorn that limits the success of durable LVADs.Despite an improvement in our understanding of RHF over the years, this common complication continues to present a considerable challenge in the overall success of durable LVADs. A basic and necessary step moving forward will be to agree on a standardized definition of RHF. In our opinion, early RHF may be best defined by the MOMENTUM criteria, as this will be most relevant for third-generation devices. For late RHF, we agree with the definition, set forth by Takeda et al., as rehospitalization following index admission . Much liAs the landscape of referrals to durable LVAD change following the 2018 UNOS allocation policy change, we must also enhance our approach to patient selection. Registry data show that patients with INTERMACS profile 3+ tend to fare better than those classified as INTERMACS 1 or 2 ,77. StraWe will need to continue to push the boundaries of therapies in the management of RHF following LVAD implantation. While we highlight a systematic strategy to approach the postoperative LVAD patient , we will


Patients have a poor prognosis and understanding the underlying pathophysiological mechanisms is crucial to guide and improve treatment. Ventricular hemodynamic forces (HDF) are a potential early marker of cardiac dysfunction, which may improve evaluation of treatment effect. Therefore, we aimed to investigate if HDF differ in patients with PHprecap compared to healthy controls. Patients with PHprecap (n = 20) and age- and sex-matched healthy controls (n = 12) underwent cardiac magnetic resonance imaging including 4D flow. Biventricular HDF were computed in three spatial directions throughout the cardiac cycle using the Navier–Stokes equations. Biventricular HDF (N) indexed to stroke volume (l) were larger in patients than controls in all three directions. Data is presented as median N/l for patients vs controls. In the RV, systolic HDF diaphragm-outflow tract were 2.1 vs 1.4 (p = 0.003), and septum-free wall 0.64 vs 0.42 (p = 0.007). Diastolic RV HDF apex-base were 1.4 vs 0.87 (p < 0.0001), diaphragm-outflow tract 0.80 vs 0.47 (p = 0.005), and septum-free wall 0.60 vs 0.38 (p = 0.003). In the LV, systolic HDF apex-base were 2.1 vs 1.5 (p = 0.005), and lateral wall-septum 1.5 vs 1.2 (p = 0.02). Diastolic LV HDF apex-base were 1.6 vs 1.2 (p = 0.008), and inferior-anterior 0.46 vs 0.24 (p = 0.02). Hemodynamic force analysis conveys information of pathological cardiac pumping mechanisms complementary to more established volumetric and functional parameters in precapillary pulmonary hypertension. The right ventricle compensates for the increased afterload in part by augmenting transverse forces, and left ventricular hemodynamic abnormalities are mainly a result of underfilling rather than intrinsic ventricular dysfunction.Precapillary pulmonary hypertension (PH Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are subgroups of PHprecap that exhibit common features of elevated pulmonary arterial pressure and vascular resistance, without an underlying pulmonary or left ventricular heart disease1. The increased pulmonary vascular resistance leads to increased pressure and influences cardiac morphology and function, leading to right heart failure and impaired filling of the left side of the heart and to premature mortality4. Alterations in pumping mechanisms may occur with preserved ventricular volumes, and current methods for monitoring treatment effect and deterioration are imprecise6.Precapillary pulmonary hypertension  computed from cardiac magnetic resonance imaging (CMR) have the potential to be used as a marker of cardiac dysfunctionprecap typically have a remodeled right ventricular anatomical shape and a pump physiology with lower LV volumes and altered LV regional contribution to stroke volume (SV), but preserved LV ejection fraction14. Previous studies have shown altered HDF in patients with volume-overloaded ventricles16. Ventricular HDF may therefore have the potential to be a more sensitive marker of pathological cardiac pumping mechanisms than typical volumetric and functional parameters in this patient cohort18, which may improve evaluation of treatment effect. The aim of this study was therefore to investigate if hemodynamic force patterns in patients with precapillary pulmonary hypertension differ compared to healthy controls.Changes in right (RV) and left (LV) ventricular volumes in patients may impact HDF, as force equals mass multiplied by acceleration. However, ventricular pumping and filling mechanisms could alter HDF even with preserved end-diastolic volume and ejection fraction, as HDF are a measure of the three-dimensional acceleration of blood. Measuring HDF over time can thus quantify the impulses causing blood to flow, which may differ between ventricles with the same volumes. Patients with PHprecap) at our tertiary PH center where CMR was performed as part of the routine evaluation, and healthy controls as a reference. Recruitment and data acquisition took place between 2016 and 2021. The patient inclusion criteria were confirmed diagnosis of PHprecap owing to either pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH).This observational study included patients being investigated for suspected precapillary pulmonary hypertension 20.Ethical approval was obtained from the Ethical Review Board, Lund, Sweden , and all participants gave written informed consent to participate prior to examination. The study was conducted in accordance with the Helsinki Declaration and reported in accordance with the STROBE recommendationsprecap. A triple-lumen Swan-Ganz catheter was used to measure mean pulmonary arterial pressure (mPAP), pulmonary artery wedge pressure (PAWP), right atrial pressure, cardiac output (CO) and pulmonary vascular resistance (PVR = (mPAP-PAWP)/CO). Measurements were obtained during free breathing in supine position with local anesthesia and were acquired as a mean value over several heart beats. PHprecap was defined by mPAP ≥ 25 mmHg at rest with PAWP ≤ 15 mmHg and PVR > 3 Wood Units according to the prevailing European Society of Cardiology/European Respiratory Society guidelines at the time of the study1. Systemic vascular resistance was calculated in Wood Units using the following formula21:Patients underwent clinically indicated right heart catheterization to confirm the diagnosis of PHMean arterial pressure was calculated non-invasively as follows: Diastolic pressure + 1/3(systolic−diastolic pressure). Mean right atrial pressure was measured invasively in patients and estimated to 3 mmHg in controls. Cardiac output was measured from CMR.26. Typical 4D flow sequence parameters were as follows: acquired temporal resolution 46 ms, acquired spatial resolution 3 mm isotropic, acceleration methods GRAPPA factor 3–4  and partial Fourier 6/8 in both phase encoding and slice encoding directions. Detailed sequence parameters are shown in Supplementary Table 28. Aliasing errors were corrected by automatic phase unwrapping with manual adjustments29.Cardiovascular magnetic resonance images were acquired at 1.5 T . The protocol consisted of standard short- and long-axis  cine balanced steady-state free precession images, as well as three-dimensional, time-resolved phase contrast flow (4D flow) images sampled from a box covering the heart and proximal great vessels using a prototype 4D flow sequence30. However, 4D flow measurements could have lower accuracy and precision in patients with right heart failure, as patients often have larger gross body motion and respiratory motion during the scan, which may result in motion artifacts. To ensure adequate data quality, we therefore performed a validation of flow volumes in 4D flow with 2D flow as the reference standard 31.Image analysis was performed using the software Segment v2.2 R7052 (32. Stroke volume (SV) was calculated for each ventricle as the difference between end-diastolic and end-systolic volumes, and ejection fraction (EF) as SV divided by end-diastolic volume. Myocardial mass was computed as the difference between epi- and endocardial volumes multiplied by an assumed myocardial density of 1.05 g/ml. Atrioventricular plane displacement (AVPD) was measured in mm as the difference of AV-plane position from end diastole to end systole, as previously described34. Peak longitudinal strain was measured in the RV and LV using manual delineations of the myocardium in end diastole in the 4-chamber long-axis view, using feature tracking in Segment v2.2 R7052.Biventricular volumes and mass were defined by semi-automatic delineation of the RV and LV endo- and epicardium in short-axis cine CMR images for the entire cardiac cycle, including papillary muscles and trabeculations to the ventricular volumes according to recommendations7. In summary, pressure gradients from 4D-flow data were computed using the Navier–Stokes equations and integrated over the RV and LV cavities defined by delineations in the short-axis cine images. Hemodynamic forces were calculated from the field of pressure gradients  analysis was used to facilitate comparison of force magnitudes in the three directions regardless of vector direction, and as a method to compare cardiac phases with large standard deviations or no clear peaks within the groups, as in previous studies2). A two-tailed p-value < 0.05 was considered significant.Statistical analyses were performed using GraphPad Prism v9.3.1 . Continuous data is presented as median and interquartile range [IQR] and categorical data as absolute numbers and proportion (%). The Mann–Whitney U test was used to compare continuous data between groups, and Fisher’s exact test was used to compare binary categorical data. Associations between HDF and SV were analyzed using linear regression analysis and coefficient of determination , missing cine slices (n = 1), congenital heart disease (n = 5), PH due to lung disease , PH due to LV disease , or no PH diagnosis (n = 7). Twenty patients  and 12 controls  were included in the final analyses.Out of 44 patients investigated for PHprecap cohort35, which were clinically assessed as not causative to PH. Thirty percent of patients were on PH-specific medical treatment at the time of CMR. There were no statistically significant differences between patients and controls in sex, body mass index, body surface area, cardiac output, cardiac index, RV SV, LV EF, or LV mass , but there was no difference between the groups in LV longitudinal strain .All patients fulfilled the criteria of precapillary pulmonary hypertension, having mPAP 41 [18] mmHg, PAWP 8 [3] mmHg and PVR 7 [5] Wood units .Left ventricular force patterns over one cardiac cycle are presented as median and interquartile range for each time point in the three orthogonal directions in Fig. LV HDF indexed to SV is presented in Fig. LV HDF in absolute values is presented in Supplementary Fig. The ratio between LV transverse and longitudinal hemodynamic forces did not differ between groups in systole or diastole (p = 0.9 for both).precap and healthy controls with 2D flow as the reference standard to ensure sufficient data quality  to patients with RV EF ≥ 50% (n = 5), patients with RV EF < 50% had increased RV transverse HDF/SV Table . PatientThere was no difference in RV or LV HDF/SV in any direction in systole or diastole between patients with cardiac output above or below median .precap, there was no correlation between pulmonary vascular resistance (PVR) and RV systolic RMS or peak HDF in the diaphragm-outflow tract direction in absolute values  or indexed to RV SV .In patients with PHprecap, and has the potential to improve guidance of treatment effect in this patient cohort.This study investigated biventricular hemodynamic forces in patients with precapillary pulmonary hypertension and healthy controls. Patients showed larger biventricular hemodynamic forces indexed to SV in all three spatial directions, indicating biventricular pathology both in pumping and filling mechanisms which cannot be explained merely by differences in blood volume. Biventricular hemodynamic force analysis may be a more sensitive marker of pathological cardiac pumping mechanisms than typical volumetric and functional parameters in patients with PH1. Septal flattening typical for patients with PHprecap was seen in our patient cohort, which may affect hemodynamic forces in both the RV and LV.Pulmonary arterial hypertension is considered to be caused primarily by vascular remodeling of the pulmonary arteries, whereas chronic thromboembolic pulmonary hypertension is mainly associated with pulmonary artery obstructions. Although the etiology differs between the two groups, the pathophysiological effects on the cardiac pumping mechanisms are similar42. Ventricular hypertrophy or dilatation may alter the myocardial structure45, leading to changes in ventricular motion and thereby affecting the intraventricular blood flow. We found no difference between patients and controls in systolic HDF indexed to SV in the apex-base direction. In the hearts of healthy subjects, SV is primarily driven by AVPD34. Patients with PHprecap and RV dilatation due to volume overload typically have preserved longitudinal contribution to SV through increased short-axis area, despite decreased tricuspid valve motion13. In the compensated stage, patients with PHprecap have preserved RV SV and cardiac output46, and our data with preserved RV SV in patients could explain the similarity in systolic force patterns in the RV apex-base direction between patients and controls, despite patients having decreased RV EF and RV AVPD. There were no correlations between HDF and pulmonary vascular resistance, indicating that HDF is a measure of intraventricular hemodynamics independent of variations in afterload.Patients had larger RV systolic HDF indexed to SV compared to controls in the two transverse directions, indicating that a larger amount of force per ml of blood volume is required in these directions to achieve RV SV. Decreased RV atrioventricular plane displacement (AVPD) and RV longitudinal strain, together with increased transverse forces in patients may indicate that to overcome the increased pulmonary arterial pressure and preserve RV SV, an increased RV contractile drive is mainly obtained in the transverse directions. In the healthy ventricle, the myocardial fibers are arranged in counter-wound helices, allowing a twisting motion during systole48. It has been shown that patients with PHprecap have a decreased RV isovolumetric relaxation time, filling rate and AVPD, with a larger contribution of atrial contraction compared to controls49. Pathological dilatation with an abnormally stretched myocardium of the RV in our patient cohort is shown by increased end-diastolic (EDV) and end-systolic (ESV) volumes. Increased diastolic forces and RV EDV but with a preserved RV SV could indicate an increased ventricular stiffness and decreased ventricular compliance, where a larger amount of intraventricular blood is accelerated compared to controls.Our data shows that patients had larger RV diastolic hemodynamic forces indexed to SV than controls in all three spatial directions. Filling of the RV in healthy hearts is mainly achieved by moving the AV plane towards the atrium, thus lengthening the ventricle and shifting the position of the tricuspid valve in relation to the bloodprecap compared to controls in the LV apex-base and lateral wall-septum directions. These two directions constitute the main direction of systolic blood flow in the healthy heart, as the lateral-wall septum direction is aligned parallel to the LV outflow tract50. Increased systolic longitudinal HDF and reduced AVPD in our patient cohort indicate an altered pumping mechanism to achieve SV. Longitudinal LV function has previously been found reduced in patients with pulmonary hypertension despite preserved LV EF51. Our study indicates that patients with PHprecap have greater variation in LV pumping mechanisms compared to controls, as systolic force indexed to SV in the LV had a larger range in patients than controls in all three directions. This is in line with previously shown heterogeneity in LV myocardial contractility in patients with PHprecap, when using myocardial strain as a measurement of deformation14. On the group level, patients with PHprecap had decreased LV SV and EDV compared to controls, indicating underfilling of the LV. Increased heart rate in patients suggest sympathetic upregulation due to underfilling, which may lead to increased LV contractility and thereby increased LV HDF/SV.Systolic HDF indexed to SV were increased in patients with PH53. Our data indicate that the anatomical deformations are mainly compensated for in the LV by alterations in fluid dynamics in the apex-base direction. However, the ratio of systolic transverse to longitudinal LV forces was preserved in patients compared to controls. Patients had increased HDF both in the lateral wall-septum and apex-base directions, and together with a preserved force ratio, this indicates that HDF in these two directions are proportionally increased in patients compared to controls.Increased HDF in the LV apex-base and lateral wall-septum directions could be linked to LV anatomical deformation, as increased pressure in the RV leads to the septum bulging into the LV during systoleprecap2, and as a consequence the LV volumes are smaller than in healthy controls. In our study, underfilling is evident from decreased LV AVPD and LV EDV in patients. The above indicate that HDF is not a substitutional measurement merely for cardiac volumes, but a measurement reflecting physiological mechanisms of the myocardium and the impact on intraventricular blood flow patterns. A recent study has shown reduced LV diastolic intraventricular pressure gradients in PHprecap using echocardiography, and this parameter was suggested as a marker of impaired LV suction in this patient group54. In contrast, another study suggested that the mechanism causing reduced LV longitudinal function in PAH is underfilling of the LV rather than an intrinsic ventricular dysfunction4. The combination of elevated diastolic HDF in the apex-base direction, no difference in LV longitudinal strain between PHprecap and controls and decreased LV volumes in our data fits best with LV underfilling in PHprecap.According to our data, smaller LV EDV does not seem to lead to distinct alterations in absolute values of LV HDF, but LV HDF were larger in patients than controls when indexed to SV. Increased resistance in the pulmonary circulation leads to a decreased filling of the LV in PHIndexing HDF to SV facilitates functional comparison between hearts of different sizes. As force is proportional to mass and acceleration, indexing HDF to SV diminishes the relevance of volumetric differences, and the acceleration component attains greater importance.In the healthy heart, systolic forces should increase proportionally to SV, as force equals mass multiplied by acceleration (Newton’s second law of motion). Increased HDF/SV indicates a larger acceleration of blood, which in turn likely follows from sympathetic upregulation with increased blood pressure to maintain cardiac output. The same principle applies in diastole, where the filling of the ventricle should equal stroke volume in the healthy heart, according to the Frank-Starling law.18. We similarly saw differences between patients with PHprecap and controls when indexing HDF to SV.Ventricular volumes play an important role in determining HDF, as a previous study has shown that HDF analysis cannot separate heart-failure patients with preserved EF from controls, but patients with impaired ventricular volumes were found to have impaired volume-normalized HDFprecap have an altered relation between force and diastolic filling compared to healthy controls.Stroke volume differed between patients and controls in the LV, but not in the RV. When quantifying RMS HDF in absolute values, differences between the groups were found in one direction in the RV and none of the directions in the LV  had right or left bundle branch block, which may affect the interpretation of the results for hemodynamic forces. However, ventricular dyssynchrony mainly affects the force ratioHemodynamic force analysis conveys information of pathological cardiac pumping mechanisms complementary to more established volumetric and functional parameters in precapillary pulmonary hypertension. The right ventricle compensates for the increased afterload in part by augmenting transverse forces, and left ventricular hemodynamic abnormalities are mainly a result of underfilling rather than intrinsic ventricular dysfunction.Supplementary Information.


CFTR) gene. These CFTR mutations lead to numerous defects in CFTR protein function. A novel class of targeted therapies (CFTR modulators) have been developed that can restore defects in CFTR folding and gating. This study aimed to characterize the functional and structural defects of S945L-CFTR and interrogate the efficacy of modulators with two modes of action: gating potentiator [ivacaftor (IVA)] and folding corrector [tezacaftor (TEZ)]. The response to these modulators in vitro in airway differentiated cell models created from a participant with S945L/G542X-CFTR was correlated with in vivo clinical outcomes of that participant at least 12 months pre and post modulator therapy. In this participants' airway cell models, CFTR-mediated chloride transport was assessed via ion transport electrophysiology. Monotherapy with IVA or TEZ increased CFTR activity, albeit not reaching statistical significance. Combination therapy with TEZ/IVA significantly (p = 0.02) increased CFTR activity 1.62-fold above baseline. Assessment of CFTR expression and maturation via western blot validated the presence of mature, fully glycosylated CFTR, which increased 4.1-fold in TEZ/IVA-treated cells. The in vitro S945L-CFTR response to modulator correlated with an improvement in in vivo lung function (ppFEV1) from 77.19 in the 12 months pre TEZ/IVA to 80.79 in the 12 months post TEZ/IVA. The slope of decline in ppFEV1 significantly (p = 0.02) changed in the 24 months post TEZ/IVA, becoming positive. Furthermore, there was a significant improvement in clinical parameters and a fall in sweat chloride from 68 to 28 mmol/L. The mechanism of dysfunction of S945L-CFTR was elucidated by in silico molecular dynamics (MD) simulations. S945L-CFTR caused misfolding of transmembrane helix 8 and disruption of the R domain, a CFTR domain critical to channel gating. This study showed in vitro and in silico that S945L causes both folding and gating defects in CFTR and demonstrated in vitro and in vivo that TEZ/IVA is an efficacious modulator combination to address these defects. As such, we support the utility of patient-derived cell models and MD simulations in predicting and understanding the effect of modulators on CFTR function on an individualized basis.Cystic Fibrosis (CF) results from over 400 different disease-causing mutations in the CF Transmembrane Conductance Regulator ( CFTR) gene that result in absent or dysfunctional CFTR protein (Cystic Fibrosis (CF) is a life-limiting recessive disease caused by mutations in the CF Transmembrane Conductance Regulator  to facilitate the approval of therapeutics for rare CFTR mutations in addition to in vitro testing systems using non-primary cells, such as Fisher Rat Thyroid (FRT) cells  simulations provide a powerful tool to understand the structural basis of CFTR protein function and explore the conformational energy landscape caused by a CFTR mutation. The combination approach of using in vitro experiments and in silico MD simulations has been used previously to characterize rare CFTR mutations (CFTR mutations is important for identifying which drug is most likely to benefit a patient.Patient-derived cell models can be used for platform . These pT) cells . CFTR-deT) cells –26 as weT) cells –31 have utations –33. UndeCFTR mutation is reported to be carried by 161 patients worldwide  in a Phase III clinical trial of 248 patients 12 years or older heterozygous for F508del, the most common CFTR mutation, and a mutation associated with residual CFTR function (13 patients with S945L)   docking . IVA, a ed cells . Howeverh S945L) . In Deceh S945L) , based ovia molecular and functional studies, which describe S945L to interfere with protein folding, channel open probability and chloride conductance  into T25 flasks coated with collagen I (Advanced Biomatrix 5015) and pre-seeded with 200,000 irradiated NIH/3T3 feeder cells. hNECs were expanded using conditionally reprogrammed cell (CRC) co-culture with NIH/3T3 feeder cells in house-made CRC culture media supplemented with ROCK (Rho kinase) inhibitor (10 μM)  –47. AftehNECs cells were seeded  onto 6.5 mm 0.4 µm Transwell porous polyester membranes (Sigma CLS3470) pre-coated with collagen I. Cells were cultured as described previously , 44, 47.Differentiated hNECs were incubated  with 3 μM VX-809 , 5 μM VX-661  or vehicle control (0.01% DMSO) for 48 h prior to experiments. For ELX/TEZ/IVA treatment, 3 μM VX-445  and 18 μM VX-661 was used. Following 48 h of pre-treatment, differentiated hNECs were mounted in circulating Ussing chambers (see Section “Quantification of CFTR-mediated ion transport in differentiated airway cell models”). 10 μM VX-770  or 0.01% DMSO was added acutely to the apical compartment of the Ussing chamber during CFTR-mediated ion transport assays.Isc, µA/cm2) was measured under asymmetric chloride (Cl−) Ringer's buffer (bicarbonate free) as previously described . Isc in response to forskolin alone (no modulator treatment) was considered as baseline activity (ΔIsc−Fsk). Cumulative changes of Isc in response to forskolin and CFTR modulator were used as the measure of total CFTR-activated currents.Differentiated hNECs were mounted in circulating Ussing chambers . Short-circuit current , was used as the loading control. Protein band densitometry was performed using ImageJ . CFTR maturation in S945L/G542X hNECs treated with LUM/IVA, TEZ/IVA and ELX/TEZ/IVA was quantified by measuring the level of mature CFTR (band C) as a fold increase compared to mature CFTR from untreated S945L/G542X hNECs. All data were normalized to the calnexin loading control.Differentiated hNECs were lysed with TNI lysis buffer   containiThe CFTR protein model used for molecular dynamics simulations was based on the ATP-bound human CFTR cryogenic electron microscopy (cryo-EM) structure (PDB ID: 6MSM) . The convia the CHARMM36m  were used to accelerate conformational transitions, in addition to simulations at physiological temperatures of 310 K (37°C). The use of elevated temperatures to study defects in mutant CFTR was validated previously  were 15.17 percentage points and 21.11%, respectively (1) significantly (p = 0.02) changed in the 24 months post TEZ/IVA initiation, becoming positive  measurements were performed (Isc (Isc-Fsk) of 12.73 ± 1.78 µA/cm2 . TEZ monotherapy produced a 1.28-fold increase in Isc-Fsk, reaching 3.53 µA/cm2 above baseline, though statistical significance was not observed . Combination therapy with TEZ/IVA led to a significant (p = 0.02) 1.62-fold increase in Isc-Fsk, reaching 7.85 µA/cm2 above baseline . CFTR-specific inhibitor (CFTRInh-172) currents mirrored the trend observed in total CFTR-activated Isc-Fsk (Isc-Fsk: 20.85 ± 2.93 µA/cm2) did not increase Isc-Fsk beyond that which was recorded for dual therapy , or direct hydrogen bonding between S945 and Y852 (State 2)  . Both stState 2) . The intState 2)  and an eState 2) .In S945L-CFTR, the mutant leucine amino acid (L) lacked the ability of WT serine (S) to form sidechain hydrogen bonds . The effIn S945L-CFTR, movement of the R domain away from its folded conformation was observed in only one of three replicate simulations at 77°C . This moUmbrella sampling calculations of the WT-CFTR free energy surface confirmed the stability of the S945-Y852 hydrogen bond . The WT-We have described patient-specific baseline CFTR function and response to CFTR-modulating drugs in nasal epithelial cell models derived from a CF individual with S945L/G542X-CFTR. Following initiation of TEZ/IVA therapy by the participant, we compared their lung function, sweat chloride concentration and nutritional parameters pre and post treatment. Furthermore, we complemented our functional studies of S945L-CFTR with molecular dynamics (MD) simulations to understand the functional and structural changes in CFTR caused by the S945L mutation.via biochemical studies. Low (<10%) band C expression of CFTR relative to WT has been reported via western blot using Chinese hamster ovary (CHO) cells (via CFTR-mediated chloride transport in patient-derived differentiated hNECs (Isc-Fsk: 12.73 ± 1.78 µA/cm2) was approximately similar to R352Q-CFTR activity (Isc-Fsk: 14.8 ± 1.4 µA/cm2), which we previously characterised as having a conductance defect (S945L-CFTR has been described previously O) cells . FurtherO) cells . In thisO) cells . S945L-Ce defect . Togethein vivo study of CFTR-dependent sweat secretion in two CF patients with S945L/G542X and S945L/F508del genotypes also demonstrated the responsiveness of S945L to IVA reporting that IVA restored near-normal function to S945L-CFTR and supporting the use of IVA as a treatment for CF patients with this allele  which suggests that S945L-CFTR complex glycosylation was impeded. Upon treatment with LUM/IVA or TEZ/IVA, band B immature CFTR was no longer present, and an increase in mature CFTR (band C) of at least 2.0-fold was observed. This supports the effectiveness of CFTR corrector(s) in correcting misfolded protein and chaperoning it to the cell surface. We reasoned it is likely that S945L-CFTR function was not significantly increased by TEZ monotherapy when CFTR-mediated ion transport was measured in Ussing chambers because the CFTR rescued to the cell surface sustained a channel gating defect.S945L is reported to have a protein maturation defect . Althoug folding , 38, thiin vitro. Furthermore, the participant showed evidence of significant clinical benefit with TEZ/IVA treatment. Lung function (ppFEV1), sweat chloride concentration, and height and weight percentiles were improved with TEZ/IVA. Although the rate of change in BMI percentile was unchanged with TEZ/IVA treatment, it is worth noting that neither was any significant effect on BMI observed in the Phase III trial evaluating TEZ/IVA in patients 12 years and older homozygous for F508del (Like the prototypical folding mutation F508del, S945L has been reported to cause multiple defects including protein maturation, channel gating and conductance . It is u F508del .in vitro response to TEZ/IVA with their in vivo response to TEZ/IVA. The correlation in the participant's drug response in vitro and in vivo supports the use of patient-derived cells for predicting patient-specific treatment response. As new therapeutic options become available and as patients receive access to multiple therapies, it will be important to determine which drug is most effective for the patient. Since the S945L mutation is approved for treatment with ELX/TEZ/IVA by the FDA (in vitro response to ELX/TEZ/IVA was approximately equal to that of TEZ/IVA. This suggests that ELX/TEZ/IVA may achieve a similar improvement in in vivo clinical outcomes for this participant as that observed upon TEZ/IVA treatment. The importance of assessing drug response on an individualised basis is emphasised by the fact that variable clinical responsiveness has been observed in clinical trials with CFTR modulators, even amongst patients with the same CFTR mutation (n = 1 studies showing that in vitro functional assessment of CFTR activity in patient-derived cell models correlates with in vivo patient outcomes (Since the approval of TEZ/IVA for S945L, the triple combination modulator therapy ELX/TEZ/IVA has expanded treatment access to more than 90% of people with CF and is currently the most effective treatment for improving patient lung function , 64. Add the FDA , it was mutation , 72. Ouroutcomes –28, suppvia response to CFTR modulators, we also used in silico protein modelling via MD simulations to determine the molecular cause of both a folding and a gating defect in S945L-CFTR. In MD simulations of WT-CFTR, a stable network of hydrogen bonds linking Y852 in the R domain to S945 on TM8 was identified. This interaction was not visible in the cryo-EM structure of the channel, where S945 faced away from Y852 (CFTR missense mutations with unique molecular phenotypes (In addition to functionally characterizing S945L rom Y852 , demonstenotypes –33.in vitro drug response correlated with the participant's in vivo clinical benefit following initiation of TEZ/IVA therapy. This highlights the importance of n = 1 clinical data used together with patient-derived cell model data, to predict CFTR drug response and evaluate the effect of novel therapeutics on CFTR function on an individualised basis. Furthermore, our study showed in vitro and in silico that S945L causes both folding and gating defects in the CFTR protein. Characterisation of the functional and structural defects of S945L-CFTR increases our understanding of CFTR folding and gating regulation and provides a potential pathway to expand further drug access to CF patients in the future.This study provides evidence that the combination of TEZ/IVA significantly increases S945L-CFTR activity in this participant's differentiated nasal cells, beyond the response to IVA alone. While S945L was initially approved for IVA, it is clear that the approval for TEZ/IVA combination therapy was appropriate, as supported by data from this study. The


Previous research has shown impaired global longitudinal strain (GLS) and slightly elevated extracellular volume fraction (ECV) in hypertensive patients with left ventricular hypertrophy (HTN LVH). Up to now, only little attention has been paid to interactions between macromolecules and free water in hypertrophied myocardium. Study Type. Single institutional case control.  To evaluate the feasibility of relaxation along a fictitious field with rank 2 (RAFF2) in HTN LVH patients. Field Strength/Sequence. Relaxation time mapping  was performed at 1.5 T using a Siemens Aera  scanner equipped with an 18-channel body array coil. Assessment. ECV was calculated using pre- and postcontrast T1, and global strains parameters were assessed by Segment CMR . The parametric maps of Tρ1 and TRAFF2 were computed using a monoexponential model, while the Bloch-McConnell equations were solved numerically to model effect of the chemical exchange during radio frequency pulses. Statistical Tests. Parametric maps were averaged over myocardium for each subject to be used in statistical analysis. Kolmogorov-Smirnov was used as the normality test followed by Student's t-test and Pearson's correlation to determine the difference between the HTN LVH patients and controls along with Hedges' g effect size and the association between variables, respectively.  9 HTN LVH  and 11 control subjects . TRAFF2 decreased statistically , and global longitudinal strain was impaired  in HTN LVH patients compared to the controls, respectively. Also, significant negative correlation was found between TRAFF2 and GLS . Data Conclusion. Our results suggest that TRAFF2 decrease in HTN LVH patients may be explained by gradual collagen accumulation which can be reflected in GLS changes. Most likely, it increases the water proton interactions and consequently decreases TRAFF2 before myocardial scarring. Hypertension is a major public health concern and leading cause of morbidity and mortality globally. Based on international guidelines, hypertension is diagnosed as having systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg . The proTρ1) characterizing irreversible myocardium injury. Tρ1 elevation has been found to be significant in the scar tissue at 4-8 weeks postinfarction in swine [Tρ1 and late gadolinium enhancement (LGE) [Relaxation during radiofrequency pulse forms an endogenous magnetic resonance contrast which is commonly used to study low-frequency interactions between macromolecular content and free water in a wide range of organs and pathologies including musculoskeletal system , 10, canin swine , 15. Alsnt (LGE) –16.n (RAFFn) and relaxation time in presence of fictitious field (TRAFFn) were developed to overcome the specific absorption rate (SAR) problem related to Tρ1 [TRAFF2 has been shown to accurately delineate myocardial infarct in a mouse model that is supported by significant correlation between tissue area with elevated TRAFF2 and Sirius red-stained histology, and TRAFF2 detected infarct sizes correlated highly with LGE in the mouse model [TRAFF2 can be used to delineate focal myocardial fibrosis with clinically acceptable SAR-values [Tρ1, TRAFF2, and TRAFF3 and concluded that increases of Tρ1 and TRAFF2 are most likely from expansion of extracellular volume, with contribution from increased fibrosis content and alterations in exchange rates [The concept of fictitious fields is originated from NMR experiments, where changes in the longitudinal magnetization are generated by a circularly polarized RF field in the xy plane. Based on fictitious field concept, relaxation along a fictitious field with rank d to T1ρ , 18. In d to T1ρ –21. Diffse model . A recenR-values . In a prge rates .The Bloch-McConnell equations are used for modeling the spatial-temporal behavior of the macroscopic magnetization in time-varying external magnetic fields. It is a suitable numerical tool to simulate chemical exchange for various applications including magnetization transfer (MT) or chemical exchange saturation transfer (CEST) imaging . Given aFeature-tracking cardiac MRI (FT-CMR) is a tissue tracking technology for noninvasive assessment of myocardial deformation in research patients . It emplT1 and ECV in HTN LVH patients without increased LGE [TRAFF2 with comparisons to FT-derived strain parameters, native T1 and ECV. Bloch-McConnell simulation was used to investigate contrast mechanisms.What is known about hypertrophied myocardium is largely based on left ventricular wall thickness, presence of LGE enhancement, and LV dysfunction detected by impaired strain parameters. Several studies have found a mild increase in native ased LGE , 34. Und2, and moderate-to-severe systolic function (LVEF < 45%).The study was approved (159/2018) by the local ethics committee, and each participant provided written informed consent. Prospectively, 9 subjects with HTN LVH  and 11 normotensive controls  were enrolled between September 2019 and April 2020. All subjects were required to sign informed consent and be in desired physical condition to undergo MR imaging. The definition of HTN LVH was systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg on at least 2 office readings or taking one or more medications for hypertension followed by maximal LVED − WT ≥ 15 mm in at least one myocardial segment in LGE . ExclusiCMR were performed at 1.5 T using a Siemens Aera  scanner equipped with an 18-channel body array coil. Measurements were ECG-gated, and imaging was performed in breath-holds.Tp 2.83 ms 0, 12, and 24 times. To synchronize RAFF2 measurements to the same cardiac phase, a variable delay was added between the R-wave and the preparation block. In addition, a crusher gradient was employed to dephase the magnetization in xy plane prior to readout. The RAFF2 imaging parameters were as follows: 6 weighted images (3 with and 3 without an inversion pulse), balanced steady-state free precession (FISP) readout with repetition time (TR) one R-R interval, echo time (TE) 3.6 ms, matrix size 192 × 156, flip angle 20°, field of view (FOV) 40 × 32.5 cm2, and slice thickness 7 mm.RAFF2 waveform was formed using sinusoidal pulse with initial 500 Hz amplitude , 18. RAFTρ1 spin-locking pulse consisted of a hard excitation pulse, two halves of spin-lock pulse with reversed phases, and hard refocusing pulse between halves to correct the heterogeneity in the B0 and transmit B1 fields [B0 direction. Spin-locking times (TSL) were 0, 15, and 30 ms, and the preparation, refocusing, and return pulse amplitudes were 500 Hz. Based on spin-lock durations, a delay was applied to synchronize the readout to a specific time after ECG R-peak. Tρ1 data were fitted using a single monoexponential decay function [1 fields , 36. Aftfunction , 36.For quality control of spin-lock power, RF field amplitude was measured using a 1 ms hard pulse with varying power from 0 to 500 Hz. The measurement parameters were TR one cardiac cycle, TE = 3.6 ms, isotropic in-plane resolution 4.2 mm, flip angle 20°, slice thickness 7 mm, and FISP readout .T1 mapping was performed using a phase-sensitive variant of the modified Look-Locker inversion recovery (MOLLI) technique with balanced steady-state free precession (b-SSFP) readout. The imaging protocol consisted of a 5 s (3 s)3 s MOLLI sequence scheme with two sets of Look-Locker. This protocol yielded 5 T1 weighted images over consecutive cardiac cycles during the first inversion recovery. Then, a three-heartbeat gap was followed by 3 T1 weighted images over consecutive cardiac cycles during the second inversion recovery [T1-mapping parameters were as follows: 8 weighted images, inversion time (TI) from 100 to 5000 ms, TR = 300/TE = 1 ms, isotropic in-plane resolution 1.2 mm, flip angle 35°, and slice thickness 7 mm. The postcontrast acquisition was performed at approximated 10 minutes after the intravenous injection of 0.3 ml/kg gadoteric acid  with following imaging parameters: 9 weighted images, TI = 100 − 4000 ms/TR = 300 ms/TE = 1 ms, isotropic in-plane resolution 2.1 mm, flip angle 35°, and slice thickness 7 mm.recovery . The natLGE images were captured using a 2D single inversion recovery prepared FISP sequence, 10 minutes after the intravenous injection. LGE images were visually evaluated for areas with elevated signal intensity following administration of contrast agent. The imaging parameters were TI = 350 ms/TR = 1100 ms/TE = 1.1 ms, isotropic in-plane resolution 2.1 mm, flip angle 40°, and slice thickness 7 mm.Multiplanar gated cine CMR was obtained using a standard balanced steady-state free precession readout. Short-axis and long-axis slices with coverage from cardiac base to apex were captured with the following parameters: number of frames 25, number of slices 13-15 depending on the size of heart, TR = 41 ms between single excitations, TE = 1.1 ms, isotropic in-plane resolution 2.1 mm, flip angle 55°, and slice thickness 8 mm.http://aedes.uef.fi/).Global strain analysis was performed using FT-CMR. Cine SSFP images in the short-axis and long-axis views were transferred into commercially available software . Initially, the endocardial and epicardial borders of the myocardial tissue were drawn in each cine MRI image. The software, then, employed a tracking strategy based on nonrigid image registration to compute interframe deformation and consequently to estimate myocardial strain curves , 25. MyoTRAFF2 and Tρ1 maps were reconstructed using Aedes software (http://aedes.uef.fi/) in MATLAB R2017b platform . RAFF2 weighted images were aligned prior to fitting procedure of RAFF2 map. The registration was performed to reduce misalignment artifacts in the final parameter fitting map using Matlab ver. R2017b Registration Estimator toolbox. Standard Siemens protocol was used for T1 motion correction and relaxation time calculation [B1 from data with varying preparation pulse duration. Native and postcontrast T1 maps were aligned using the same registration function as RAFF2. ECV was calculated based on changes within native and postcontrast longitudinal relaxation rates (R1) and the patient's haematocrit (HCT from 0.37 to 0.47) value with following formula [culation . Cycle f formula :(1)ECV=TRAFF2, Tρ1, T1, and ECV maps and LGE images by one observer. ROIs were traced with margins to stay safely inside the myocardium and avoid partial volume effect. Segment-wise analysis was performed for ECV and TRAFF2. Imaging data was acquired in mid-ventricular slice, and values therefore reported only respective AHA 17 model segments.Myocardia were delineated manually, as region of interest (ROI), using Aedes software from t-test was used to compare the mean difference between the HTN LVH patients and controls in all variables. Also, the comparison was conducted in mid-layer segments for ECV and TRAFF2. Hedges' g effect size was calculated as the practical significance representing the standardized difference between means. Association between variables was assessed using Pearson correlation coefficients. An alpha level of 0.05 was used for all statistical tests.Analysis was performed using SPSS software . Continuous data are presented as means ± standard deviation and categorical data as the number (%). The normality was confirmed by the Kolmogorov-Smirnov test. Student's TRAFF2 was estimated using Bloch-McConnell equation in MATLAB  with a single monoexponential function for the decay of magnetization as described in [T1 = 950 ms, T2 = 50 ms, and chemical shift = 1 ppm.The value of ribed in , 18. A tribed in , T1 = 95TRAFF2, from 0.6 to 0.56, when increasing the -OH group concentration from 0.3 M to 0.5 M (P < 0.01) with a significantly reduced TRAFF2  and impaired global radial and longitudinal strains . A significant decrease was found in septal wall (segment 8 and 9) of HTN LVH patients using TRAFF2 (P < 0.05)  as observed for strain parameters. In addition, TRAFF2 was correlated with LVED-WT, LVED mass, GLS . The highest correlation was observed between TRAFF2 and LVED mass .Bloch-McConnell simulations showed a constant exponential decay in to 0.5 M . Compare < 0.05) . Substan < 0.05) ; howeverass, GLS , and ageT1 values compared to the control group . Our analysis demonstrated a significant enlargement in LVED-WT, LVED mass (P < 0.01), and borderline LVEF  in HTN LVH patients. No noteworthy difference was observed between HTN LVH patients and controls in LGE images (Student's t-test  P > 0.05). Tρ1 was not correlated with T1 and heart rate (P > 0.05). Altogether, these results show mildly impaired LV systolic function and hypertrophied myocardium with elevated ECV and T1 in HTN LVH patients  of HTN LVH patients compared to controls. This result may be explained by the fact that fibrotic replacement is gradual as disease develops from collagen deposition to increased extracellular space.Hemodynamic burden is a significant contributory factor to the development of LVH. The increase in LV mass and wall thickness occurs to compensate chronic pressure overload in hypertensive patients. However, it is the cellular and molecular response to sarcomere-gene mutations that induce collagen deposition and fibrotic remodeling . Increaspatients , 34. OurTρ1 and aging which confirms those of Wang et al. who also found that there is no association between Tρ1 and aging in myocardium [TRAFF2 with increasing subject's age. Aging is a slow but life-long process associated with physiological changes in all organ systems. It increases arterial wall thickening and stiffness due to deposition of collagen and microscopic changes in cardiovascular systems [TRAFF2 changes may partly be explained by the increased water proton interactions due to aging. The Bloch-MocConnell equations were used to simulate chemical exchange as the source of contrast mechanism in TRAFF2. Our results showed that there is a major difference between simulations (~600 ms) and measurements in vivo (~80 ms). The primary cause of the discrepancy is in numerous relaxation channels in vivo contributing to TRAFF2, while only proton exchange is resembled with Bloch-McConnell equations.Our results showed no correlation between ocardium ; however systems . Therefor = 0.42, P < 0.002) and LVEF  in hypertensive patients [Several studies have shown impaired GLS in HTN LVH patients without LGE enhancement despite preserved LVEF –32. GLS The present study has some limitations. A small sample size and single center measurements were the most evident constraints. Also, the study was exploratory in nature with multiple measures being compared and correlated without correction for multiple comparisons leading to the increased risk of false positive findings. Prospective and diverse multicenter studies with the heterogeneous group of patient population are necessary to generalize our findings. Prognostic data are also needed to evaluate the prognostic value of the RAFF and FT-CMR strain in HTN LVH patients. Software packages are another limitation in our work. Since there is no standard protocol used in software packages, different registration framework or FT-CMR software package is possibly to introduce variability into our results. This might affect strain values or out-of-plane movement correction.TRAFF2 and myocardial strain in the absence of scar tissue and mild diffuse fibrosis in hypertrophied myocardia. Most likely, augmented collagen content increases the water proton interactions which leads to a decrease in TRAFF2 of hypertrophied tissue when extracellular space is still close to intact. Both theoretical simulation and empirical evidence support this hypothesis. TRAFF2 can shed new light on early changes in myocardial pathology with preserved LVEF.Our results demonstrate a good agreement between decreased


Myocardial strain is reported to be a sensitive indicator of myocardial mechanical changes in patients with hypertrophic cardiomyopathy (HCM). The changes in the mechanics of the myocardium of normal wall thickness (< 12 mm) have yet to be well studied. This study aimed to evaluate the function of myocardial segments of normal thickness in patients with HCM.p < 0.05 was considered statistically significant.Sixty-three patients with HCM and 30 controls were retrospectively enrolled in this retrospective study. Cine imaging, native and post-contrast T1 maps, T2 maps, and late gadolinium enhancement were performed. In addition, regional myocardial strain was assessed by cardiac magnetic resonance-tissue tracking. Strain parameters were compared between the controls and HCM patients with segments of the myocardium of normal thickness. Subgroup analysis was conducted in obstructive and non-obstructive HCM. Lastly, p = 0.002; circumferential, 1.28  vs. 1.39 , p < 0.001; and longitudinal, 1.16  vs. 1.28 , p < 0.001). The normal-thickness segments showed no significant difference in systolic PSRs between HCM and the controls. In the subgroup analysis, significantly decreased diastolic PSRs were noted in both obstructive and non-obstructive HCM, compared with the controls (p < 0.05).In normal-thickness myocardial segments of HCM (n = 716), diastolic peak strain rates (PSRs) were significantly lower than in the control group (n = 480) (radial, − 2.43  vs. − 2.67 , Diastolic changes in myocardial mechanics were observed in normal-thickness segments of HCM, occurring before morphological remodeling and systolic dysfunction developed. This finding contributed to a better understanding of the mechanical pathophysiology of HCM with preserved left ventricular ejection fraction. It may potentially aid in predicting disease progression and risk stratification.The online version contains supplementary material available at 10.1186/s12880-022-00955-7. Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular (LV) thickening that cannot be explained by an abnormal load or other cardiac or systemic diseases , 2. The The end-stage of HCM is characterized by systolic dysfunction (left ventricular ejection fraction [LVEF] < 50%) . In the In HCM patients with normal LVEF, the non-hypertrophied segments motion has been shown to be impaired or display compensatory hypercontractility , 9, 13. This study aimed to investigate the regional function of segments with normal thickness using CMR-TT, to better understand the pathophysiology of HCM with preserved LVEF. In addition, the goal is to find a new biomarker in HCM patients that is potentially useful for monitoring the disease progression.We retrospectively enrolled 63 HCM patients who underwent contrast-enhanced CMR imaging in our institution from May 2018 to January 2020 and 30 healthy controls matched for age and sex . CMR protocols included cine in the short- and long-axis , native and post-contrast T1 mapping, T2 mapping in three short axis slices , and late gadolinium enhancement (LGE) images at the exact location as the short-axis cine slices.2; slice gap = 2 mm; bandwidth = 965 Hz/pixel; FOV = 360 × 360 mm2; and 25 calculated phases per heartbeat.A standard breath-hold cine imaging with steady-state free precession (SSFP) sequence was acquired. The parameters were as follows: echo time (TE) = 1.4 ms; repetition time (TR) = 3.1 ms; flip angle (FA) = 55°; slice thickness = 8 mm; voxel size = 1.9 × 1.9 mm2. Furthermore, T2 mapping was generated using a T2-prepared bSSFP sequence with three T2 preparation times: 0, 24, and 55 ms. The T2 parameters were as follows: TE = 1.41 ms; TR = 3.3 ms; FA = 12°; slice thickness = 5 mm; voxel size = 1.9 × 1.9 mm2; and acquisition matrix = 206 × 256.T1 mapping was acquired by using a single breath-hold Modified Look-Locker Inversion recovery sequence. In addition, 5b(3b)3b and 4b(1b)3b(1b)2b schemes were used for the native and post-contrast T1 imaging, respectively, 15–20 min after administration of a contrast agent dose . The T1 parameters were as follows: TE = 1.2 ms; TR = 3.8 ms; FA = 35°; slice thickness = 5 mm; and voxel size = 1.4 × 1.4 mm2.LGE imaging was performed 10–15 min after administration of the contrast agent using an inversion recovery prepared pulse and segmented FLASH sequence with a phase-sensitive reconstruction technique. Imaging parameters were as follows: TE = 1.2 ms; TR = 5.2 ms; FA = 55°; slice thickness = 8.0 mm; and voxel size = 1.5 × 1.5 mmAll CMR images were analyzed with commercial software  according to the 16-segment American Heart Association (AHA) model .Contours in the endo- and epi-myocardium at the LV end-diastolic phase without papillary muscle were automatically sketched and manually corrected on a short-axis cine by a radiologist with 3 years of experience using the short-3D module Figure . In addiThen, the cine images of the short and long axes were loaded into the Tissue Tracking module to outline the endocardium and epicardium and generate segmental strain parameters, including the peak strain (PS), systolic peak strain rate (PSR) and diastolic PSR in the radial, circumferential, and longitudinal directions.According to the maximum thickness of the myocardium, the total HCM segments were divided into group A (< 12mm) , group Bmyo post − 1/T1myo pre) × (1 − Hct)/(1/T1blood post − 1/T1blood pre)16. T1myo post and T1myo pre represented the post- and pre-contrast myocardial T1 values, respectively, whereas T1blood post and T1 blood pre were the post- and pre-contrast blood T1 value [Segmental native T1 and T2 values were obtained by manually delineating the endocardium and epicardium of the entire LV myocardial region (which included the LGE-positive regions) on the T1 and T2 mapping images . Then, tT1 value . The HctT1 value , 20. In We randomly selected 20 patients for inter- and intra-observer agreement analysis. The strain parameters were measured independently by two blinded observers , one of whom re-measured the strains after one month (J.H.Q).t-test or Mann–Whitney U-test was performed to compare two groups of continuous variables. The Kruskal–Wallis rank test was used to analyze the differences among three or more groups. In addition, Bonferroni’s correction was conducted to perform post-hoc comparisons. The association between myocardial thickness and other quantitative myocardial parameters  was evaluated with the Spearman correlation, which had the following values: Spearman correlation value of 0.00–0.10 was considered a negligible correlation; 0.10–0.39, weak correlation; 0.40–0.69, moderate correlation; 0.70–0.89, strong correlation; and 0.90–1.00, very strong correlation [p-value < 0.05 was considered statistically significant.All statistical analyses were performed using SPSS Statistics 22 . Categorical variables were presented as frequencies (percentages) and analyzed with Pearson’s chi-squared test. The normality distribution of the continuous data was determined by the Shapiro–Wilk test. Continuous variables were expressed as mean ± standard deviation or median (interquartile range). An independent relation . FurtherTable p < 0.001, p = 0.03, and p = 0.04, respectively) .Compared with the controls, patients with HCM had a significantly increased myocardial mass index, cardiac output, and stroke volume (y) Table . Howeverp < 0.05). Notably, there was a significant difference in the native T1 (p < 0.001) between group A and the control group but no such difference in T2 (p = 0. 59) or ECV (p = 0. 99).There were 716 segments in group A, 111 in group B, and 181 in group C. As shown in Table p < 0.05). In addition, the demographic characteristics of the subgroups are shown in the supplementary materials . The EDTH was weakly correlated with the extent of LGE  and native T1 .As demonstrated in Table As shown in Table We found that in HCM patients, the diastolic PSR of segments with normal thickness (< 12 mm) were impaired in the radial, circumferential, and longitudinal directions compared with the controls. This finding suggested that functional remodeling with changes in diastolic dysfunction may precede morphological remodeling in normal-thickness HCM segments.We observed that diastolic PSR decreased in all segments. In contrast, PS and systolic PSR were impaired in segments with a thickness ≥ 12 mm , indicatIn the subgroup analysis, there were no significant differences between obstructive and non-obstructive HCM in diastolic PSR for the normal-thickness wall segments. However, Zhao et al.  reportedConsistent with the study by Swoboda et al. , this stWe performed a correlation analysis to explore myocardial changes that occurred with the variation in wall thickness. The segmental strain index showed a better correlation with myocardial thickness than LGE, consistent with previous reports , 30. ThiOur study had several limitations. First, there was a lack of genetic results for our participants, and the effects of different genotypes on normal-thickness segment strain should be explored in future studies. Second, this study only included patients with localized basal septal hypertrophy and reverse curvature septal hypertrophy categories as reported in a previous study , due to In conclusion, ventricular diastolic dysfunction was observed in normal-thickness wall segments in HCM patients, a process that preceded morphological remodeling. This finding contributed to a better understanding of HCM pathophysiology of and may potentially help predict disease progression and risk stratification in patients with HCM.Additional file 1: Table S1. Clinical characteristics and CMR imaging findings in obstructive and non-obstructive HCM patients and controls


The aims of our study were (1) to assess the right ventricular (RV) myocardial mechanics by two-dimensional (2D) and three-dimensional (3D) speckle-tracking echocardiography (STE) in patients with an ischemic or non-ischemic etiology of end-stage heart failure (HF) and (2) to explore which RV index evaluated by 2D- and 3D-STE was the most powerful indicator for identifying the ischemic and non-ischemic etiologies of end-stage HF.A total of 96 patients with left ventricular ejection fraction (LVEF) < 30% were enrolled in our study: 42 patients  with ischemic cardiomyopathy and 54 patients  with non-ischemic cardiomyopathy. A total of 45 healthy subjects  served as controls. The longitudinal strain of the RV free wall (RVFWLS) was determined by both 2D- and 3D-STE.P < 0.05). Patients with non-ischemic cardiomyopathies (NICMs) had significantly lower 3D-RVFWLS and RVEF values than in those with ischemic cardiomyopathies (ICMs), whereas 2D-RVFWLS and conventional RV function parameters did not differ between the two subgroups. RVEF was highly related to 3D-RVFWLS , modestly related to 2D-RVFWLS , and weakly related to conventional RV function indices . Receiver operating characteristic curve analysis revealed that the optimal 3D-RVFWLS cut-off value to distinguish NICM from ICM patients was –14.78% , while 2D-RVFWLS and conventional RV echocardiographic parameters did not.Compared to controls, patients with an ischemic or non-ischemic etiology of end-stage HF had lower 2D-RVFWLS, 3D-RVFWLS and RV ejection fraction (RVEF) values (Our study demonstrated the superiority of 3D-RVFWLS over 2D-RVFWLS and conventional RV function indices in identifying the ischemic and non-ischemic etiologies of end-stage HF. These findings support the idea that 3D-RVFWLS may be a promising non-invasive imaging marker for distinguishing NICM from ICM. Right ventricular (RV) function has a powerful capability for risk-stratifying patients with heart failure (HF) –3. In thEchocardiography, which is readily available and relatively inexpensive, is considered a first-line modality for assessing ventricular performance. Nevertheless, completing an accurate assessment of RV function by traditional echocardiography is challenging because of its complex structure, contraction pattern, and response to overload. Two-dimensional (2D) speckle-tracking echocardiography (STE) is an angle-independent, less load-dependent technique that allows for the earlier identification of subtle RV dysfunction. It has been demonstrated to be a more reliable and accurate tool for RV function assessment than conventional RV function indices –10. HoweThus, the purposes of our study were (1) to assess RV myocardial mechanics using 2D- and 3D-STE in subjects with an ischemic or non-ischemic etiology of end-stage HF and (2) to explore which RV index evaluated by 2D- and 3D-STE has the potential to differentiate between the ischemic and non-ischemic etiologies of end-stage HF.This was a prospective study of 109 consecutive patients with end-stage HF who required heart transplantation (HT) and were enrolled in this study at the Wuhan Union Hospital from June 2018 to July 2021. All patients had severely impaired left ventricular (LV) function [LV ejection fraction (LVEF) < 30%] , and theSeparately, we enrolled a control group of 45 healthy volunteers with a similar age and sex breakdown with no cardiovascular disease on the basis of clinical examination, electrocardiography, echocardiography, and chest X-ray imaging. This study was approved by the ethics committee of Tongji Medical College, Huazhong University of Science and Technology, and written informed consent was obtained from all participants.All patients underwent transthoracic echocardiograms using the Philips EPIQ7C ultrasound machine . LV and RV parameters were measured according to the guidelines of the American Society of Echocardiography . The RV 2 = LVEDV/BSA), LVESVI (ml/m2 = LVESV/BSA), LV mass index (LVMI) (g/m2 = LVM/BSA), and LV global longitudinal strain (LVGLS) were obtained. The frame rate range of the 3D STE images was set at approximately 20 Hz or more.2D-STE and 3D-STE analyses were performed using commercial software . For 2D-STE analysis, RV endocardial tracings were manually performed in the apical 4-chamber view. The software automatically tracked the speckle patterns in the myocardium. The endocardial border could be manually modified if necessary. Ultimately, the software generated the longitudinal strain curves and longitudinal peak systolic strain values of 6 segments of the RV. The 2D longitudinal strain of the RV free wall (2D-RVFWLS) was defined as the mean value of three segments of the RV free wall . For 3D-A total of 28 patients underwent cardiac magnetic resonance (CMR) examinations to assess RVEF within 1 day of echocardiography since CMR was regarded as the gold standard for RV systolic function. CMR imaging was analyzed using conventional CMR software . RV endocardial contours were manually traced on all short-axis slices on the end-diastolic and end-systolic frames by an experienced operator who was blinded to echocardiographic measurements. Finally, the software automatically obtained the CMR-RVEF.All patients underwent right heart catheterization before HT. A Swan-Ganz catheter were used to acquire cardiac hemodynamic data. Right atrial pressure and pulmonary artery pressure were obtained from right heart catheterization.post hoc test or by Student’s t-test when only two groups were compared. For non-normally distributed data, Man-Whitney U test and Kruskal-Wallis test were used. Logistic regression analysis was used to evaluate the effect of explanatory variables. To calculate the sensitivity and specificity at various cutoff levels for the selected parameters, receiver operating characteristic (ROC) curves were used. Pearson’s correlation coefficient was used for the assessment of correlations. Bland–Altman analysis and the intraclass correlation coefficient (ICC) to assess the consistency between 2D- and 3D-STE parameters were applied ,and categorical variables are expressed using frequency (percentage) values. Statistical significance was assessed by 1-way ANOVA followed by the Bonferroni  applied . The SPSThe intra- and inter-observer variability of 2D- and 3D-STE parameters were evaluated by Bland–Altman analysis and the ICC. To assess the reproducibility, 20 patients were randomly selected from our study. For the assessment of intra-observer variability, the data were re-analyzed by the same investigator after 1 month. For the evaluation of inter-observer variability, the second investigator re-analyzed the data while blinded to the values obtained by the first investigator.P < 0.001), although they remained within the normal ranges. Compared to the controls, patients with ICM and NICM had increased RVEDVI, RVESVI, RVD1, RVD2, RVD3, RIMP, LVEDVI, LVESVI and LVMI values (P < 0.05), and decreased LVEF, LVGLS, TAPSE, RVFAC, tricuspid s’, RVEF, 2D-RVFWLS, and 3D-RVFWLS values (P < 0.05). Patients with NICM had decreased 3D-RVFWLS and RVEF values, and increased RVEDVI and RVESVI compared to those with ICM (P < 0.05); however, no significant differences in LVEDVI, LVESVI, LVMI, LVEF, RVD1, RVD2, RVD3, conventional RV function parameters , LVGLS and 2D-RVFWLS between the two subgroups were identified in our study. The severity of TR was similar between the ICM and NICM subgroups. CMR and right heart catheterization data were not significantly different between the groups  were men. Eighty (83.8%) patients had NYHA functional class IV. Tricuspid regurgitation (TR) was absent in 22 (22.9%), mild in 29 (30.2%), moderate in 17 (17.7%), and severe in 28 (29.2%) patients with end-stage HF, respectively. The clinical and echocardiographic data of the study participants are listed in e groups . In addiP = 0.001). 3D-RVFWLS, 2D-RVFWLS, LVGLS, and conventional RV function echocardiographic parameters were entered into ROC analysis to distinguish NICM and ICM patients from each other. ROC analysis revealed that the optimal cutoff value of 3D-RVFWLS was –14.78%, with a sensitivity of 85.2% and a specificity of 50.5%, for distinguishing between the ischemic and non-ischemic etiologies of end-stage HF   . 2D-RVFWr = 0.70, P < 0.001). Good consistency for RVFWLS as assessed by 2D- and 3D-STE, respectively, was noted .r = 0.72, P < 0.001), modestly correlated with 2D-RVFWLS ; and weakly associated with RVFAC , TAPSE , RVEDVI , RVESVI , and RVSV . Meanwhile, RVEF was not associated with RVD1, RVD2, RVD3, RIMP, or tricuspid s’. Moreover, 3D-RVFWLS correlated better with RVEF than 2D-RVFWLS and the conventional RV indices with RVEF . In addition, we found that CMR-RVEF was modestly correlated with 3D-RVFWLS , and weakly associated with 2D-RVFWLS   .The reproducibility of 2D- and 3D-STE parameters is shown in To our knowledge, this may be the first investigation to comprehensively assess RV function in patients with ischemic and non-ischemic etiologies of end-stage HF using 2D- and 3D-STE and conventional echocardiographic parameters. The main findings of our study were as follows: (1) patients with ischemic or non-ischemic etiology of end-stage HF had diminished 2D- and 3D-RVFWLS compared to healthy controls; (2) patients with NICM had lower 3D-RVFWLS compared to ICM patients, although no significant difference in 2D-RVFWLS between these two subgroups was noted in our study; and (3) more importantly, ROC analysis revealed that 3D-RVFWLS displayed the potential for distinguishing NICM patients from ICM patients, while 2D-RVFWLS and conventional RV echocardiographic parameters did not. Therefore, 3D-STE may be superior to 2D-STE for distinguishing between the non-ischemic and ischemic etiologies of end-stage HF.Our results showed that 2D- and 3D-STE parameters were reduced in patients with ischemic or non-ischemic etiology of end-stage HF compared to healthy controls. These results are consistent with prior findings gathered using 2D-STE , 21. OurDifferentiating NICM patients from ICM patients is essential on account of the different prognoses and treatment strategies for each group . AlthougOwing to the complex geometry of the RV, 3D-STE has no geometric assumptions or out-of-plane motion of speckles, allowing for a more accurate assessment of myocardial performance by overcoming the limitations of 2D-STE. There were significant correlations between the RVFWLS values obtained by the 2D and 3D modalities. These findings were consistent with those of previous studies in patients with pulmonary hypertension . RV contOur findings showed that there was a significant correlation between CMR-RVEF and 2D- and 3D-RVFWLS. This is compatible with findings of previous research, which demonstrated that CMR-RVEF was strongly related to 2D-RVFWLS . 3D echoUnlike structurally normal hearts, patients with end-stage HF present with marked ventricular remodeling that may be better served by the 3D algorithm. Although 3D-STE has a theoretical superiority over 2D-STE for RV quantification, head-to-head comparisons between 3D-STE and 2D-STE for assessing RV strain in patients with end-stage HF have not yet been performed. Our results demonstrated the superiority of 3D-STE over 2D-STE and conventional RV echocardiographic indices in reflecting the RV myocardial pathophysiology in relation to the ischemic and non-ischemic etiologies of end-stage HF. Considering that 3D-STE better detects the changes in RV strain compared to 2D-STE in patients with ischemic and non-ischemic etiologies of end-stage HF, it should be the optimal choice for the assessment of RV strain in patients with end-stage HF. Additionally, we noted that 3D-RVFWLS was significantly related to 2D-RVFWLS and RVEF, and there were good consistency for RVFWLS as assessed by 2D- and 3D-STE, only 3D-RVFWLS can distinguish NICM patients from ICM patients, while 2D-RVFWLS and RVEF failed to distinguish these. Therefore, we suggest that 2D-STE and 3D-STE values should not be used interchangeably in patients with end-stage HF.The present study had several limitations. First, 3D-STE analysis requires better image quality and experienced operators, and the technique is in its infancy and not yet widely validated for clinical use. Second, 3D-STE is hindered by low frame rates, which may have an effect on strain values. Third, we enrolled only patients with end-stage HF in this study, which may have led to a selection bias and an inability to generalize our findings to all patients with HF. Fourth, some patients with end-stage HF who were RV-paced or in a clinically critical state were not deemed suitable to undergo CMR examinations, so we could not obtain CMR data from all included patients. Fifth, although 3D-RVFWLS can distinguish NICM patients from ICM patients, while specificity of 50.5% is not so good. Sixth, 3D-STE parameters have vendor dependency ; thus, oOur study demonstrated the superiority of 3D-RVFWLS over 2D-RVFWLS and conventional RV echocardiographic indices in identifying the ischemic and non-ischemic etiologies of end-stage HF. These findings indicate that 3D-RVFWLS may be a promising non-invasive imaging marker for distinguishing NICM from ICM.The original contributions presented in the study are included in the article/The studies involving human participants were reviewed and approved by the Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology. The patients/participants provided their written informed consent to participate in this study.FT, YG, YZ, BZ, YX, SY, JW, YY, QL, LZ, YML, and MX: conception and design of the study. FT, YG, YZ, YML, and MX: acquisition of data. MQ, YXL, SZ, YX, WW, SC, LZ, YML, and MX: analysis and interpretation of data. YML and MX: drafting the article. 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.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.