Uremic cardiomyopathy (UC), the peculiar cardiac remodeling secondary to the systemic effects of renal dysfunction, is characterized by left ventricular (LV) diffuse fibrosis with hypertrophy (LVH) and stiffness and the development of heart failure and increased rates of cardiovascular mortality. Several imaging modalities can be used to obtain a non-invasive assessment of UC by different imaging biomarkers, which is the focus of the present review. Echocardiography has been largely employed in recent decades, especially for the determination of LVH by 2-dimensional imaging and diastolic dysfunction by pulsed-wave and tissue Doppler, where it retains a robust prognostic value; more recent techniques include parametric assessment of cardiac deformation by speckle tracking echocardiography and the use of 3D-imaging. Cardiac magnetic resonance (CMR) imaging allows a more accurate assessment of cardiac dimensions, including the right heart, and deformation by feature-tracking imaging; however, the most evident added value of CMR remains tissue characterization. T1 mapping demonstrated diffuse fibrosis in CKD patients, increasing with the worsening of renal disease and evident even in early stages of the disease, with few, but emerging, prognostic data. Some studies using T2 mapping highlighted the presence of subtle, diffuse myocardial edema. Finally, computed tomography, though rarely used to specifically assess UC, might provide incidental findings carrying prognostic relevance, including information on cardiac and vascular calcification. In summary, non-invasive cardiovascular imaging provides a wealth of imaging biomarkers for the characterization and risk-stratification of UC; integrating results from different imaging techniques can aid a better understanding of the physiopathology of UC and improve the clinical management of patients with CKD. In patients with chronic kidney disease (CKD), an increased rate of adverse cardiovascular (CV) events with a worsening of renal function has been observed . AccordiEchocardiography represents the first-line modality used for the investigation of UC, and many data are currently available from the literature. Though limited by geometric assumptions, especially when 2D imaging is used , the evaChanges in myocardial function characterize the natural history of UC, with diastolic rather than systolic abnormalities representing a key feature. A longitudinal study analysing patients with ESRD undergoing replacement therapy found that diastolic abnormalities preceded the reduction of left ventricular ejection fraction, which became evident only at year three after the baseline evaluation . FurtherSystolic dysfunction, as signified by reduced left ventricular ejection fraction (LVEF), develops later in the course of UC but retains prognostic value and might improve after kidney transplantation . SpeckleVascular and cardiac calcification may be easily identified but less easily quantified by echocardiography, though some methods have been developed for a quantitative calcium evaluation and retain prognostic significance . In patiOther features of UC are less effectively imaged by echocardiography. Vascular stiffness is hardly imaged directly by echocardiography, where the gold-standard for the assessment of pulse wave velocity (PWV) is calculation tonometry or through mechanotransducers . HoweverMost of the evidence that links CKD and LVH derives from studies performed with echocardiography, though CMR offers undeniable advantages. Indeed, echocardiography systematically overestimates myocardial mass  and is sCMR is the technique of choice for non-invasive detection of fibrosis. Late gadolinium enhancement (LGE) imaging detects areas of dense, replacement fibrosis. This assessment implies the use of gadolinium-based contrast agents (GBCAs), which is controversial in patients with advanced renal disease because of the risk of development of systemic nephrogenic fibrosis. However, the risk is negligible with the widespread use of more stable macrocyclic compounds; accordingly, the most recent consensus documents do not restrict its use in CKD, as long as low risk GBCAs are used , which e2. Native T1 emerges as an early marker of cardiac disease in CKD, with increased values independent of the presence of LVH and conventional risk factors [The assessment of diffuse myocardial fibrosis has gained weight in the last few years, with the use of T1 and T2 parametric mapping sequences. Although T1 mapping is very sensitive to myocardial pathology, it lacks specificity; its increase may be due to fibrosis, but also to edema or infiltration. On the contrary, T2 mapping is specifically increased in the presence of myocardial water, therefore the combination of both of these offers more valuable information. Multiple studies have reported significant differences in T1 and T2 between CKD and subjects with normal renal function ,26,27,80 factors  and main factors ,82 and tBoth T1 and T2 were independently related to biomarkers of myocardial injury (hs-TnT) and B-type natriuretic peptides ,28, showA recent cross-sectional study, including the whole range of renal disease (stages 2–5), demonstrated a stepwise increase in native T1 and T2 and serum biomarkers with every stage of CKD . MoreoveT1 mapping is a relevant prognostic marker in a variety of cardiac conditions, but outcome data reporting the prognostic value of T1 in the context of CKD are still scarce. A small study that included 52 HD patients showed that, after 38 months of follow-up, native T1 independently predicted major adverse cardiovascular events (MACE) . AdditioObservational studies have described increased aortic stiffness, measured as PWV or distensibility, across the spectrum of CKD ,23,64,65Other UC features that can be imaged by CMR include microvascular dysfunction by perfusion imaging, which, in one study, was more frequently found in CKD patients than in controls , and diaCT does not represent the first-line test of choice for evaluating cardiovascular involvement in CKD, and imaging biomarkers derived from this modality are not as robust as those obtained by echocardiography and CMR. However, CT of thorax and/or abdomen, performed with other indications, can provide additional ancillary data to support a diagnosis of UC. Myocardial end-diastolic volume and mass can be quantified even with ECG-triggered CT . In patiCKD presents with common and extensive arterial and valvular calcification  due to aThe evaluation of myocardial tissue composition by CT is a promising field from which some data are emerging. Extra-cellular volume can be quantified by CT, demonstrating high reproducibility and an age-related increase, which suggest the marker to be consistent with the actual pathologic changes in the myocardium . In patiMultiple imaging modalities contribute to a comprehensive and complementary overview of UC. Echocardiography is a widespread and cheap technique that can be used as a first-line imaging test to assess end-organ damage in CKD. CMR is generally less available than echocardiography; however, it can provide more accurate information to aid an early diagnosis of cardiac involvement in CKD, with its imaging biomarkers more suitable for use as surrogate endpoints in clinical trials testing newer therapeutic approaches. Finally, CT is rarely used to specifically assess UC. Nonetheless, the use of this imaging test is widespread, and much information can be drawn from the ancillary cardiovascular findings obtained during examinations performed with other indications. In summary, a multimodal approach, integrating results from different imaging techniques, can aid a better understanding of the physiopathology of UC and improve the clinical management of patients with CKD.


Drosophila melanogaster, is a particularly suitable model for cardiac studies. Optical coherence microscopy (OCM) captures in vivo cross-sectional videos of the beating Drosophila heart for cardiac function quantification. To analyze those large-size multi-frame OCM recordings, human labelling has been employed, leading to low efficiency and poor reproducibility. Here, we introduce a robust and accurate automated Drosophila heart segmentation algorithm, called FlyNet 2.0+, which utilizes a long short-term memory (LSTM) convolutional neural network to leverage time series information in the videos, ensuring consistent, high-quality segmentation. We present a dataset of 213 Drosophila heart videos, equivalent to 604,000 cross-sectional images, containing all developmental stages and a wide range of beating patterns, including faster and slower than normal beating, arrhythmic beating, and periods of heart stop to capture these heart dynamics. Each video contains a corresponding ground truth mask. We expect this unique large dataset of the beating Drosophila heart in vivo will enable new deep learning approaches to efficiently characterize heart function to advance cardiac research.The heart of the fruit fly,  Drosophila melanogaster (a fruit fly) is a powerful model organism for investigating biological mechanisms of human diseases. The fully sequenced D. melanogaster genome contains functional homologs for about 75% of human disease-causing genes2. The fruit fly’s short life cycle, ~ 11 days from embryo to adult, makes it a good candidate for studying age- and disease-related physiological changes. The heart, located ~100 μm below the dorsal surface, is easily accessed by optical imaging. Oxygen transport in Drosophila is independent of the tubular heart3, enabling the creation of severe cardiac defects without causing death. This independence also enables pacing experiments that can completely stop the heartbeat or accelerate the heart rate. In building an innovative research platform for cardiovascular studies, our research group has developed an integrated apparatus that can simultaneously perform optical imaging and optogenetic pacing to control and characterize the fly heartbeat rhythm at all developmental stages5. The technique employs genetically modified flies and a custom-built optical coherence microscopy (OCM) imaging system.7, cardiology10, endoscopy13, dermatology16, and dentistry19. OCM20, which integrates OCT and confocal detection, offers high resolution at an image penetration depth of around 500 µm, deep enough to image the larval, pupal, and adult Drosophila heart. For functional analysis, M-mode images are acquired with repeated frames showing cross-sectional views of the heart at a fixed location over time. In our study, each ~32-second recording captures 4000 2D images at a frame rate of ~125 frames per second. This 2D+ time OCM video acquisition is less sensitive to sample motion and supports higher frame rates, enabling more accurate measurements, especially of fast beating hearts.Optical coherence tomography (OCT) noninvasively provides micron-scale cross-sectional and 3D images of biological tissues in a wide variety of clinical applications, including ophthalmologyDrosophila, there are several challenges to quantify the heart function: adequate spatiotemporal resolution with minimum invasiveness, and reliable automatic algorithm for batch processing. Previous techniques using a digital camera or electrophysiological recordings are able to resolve the heart function for quantification, but require invasive dissection procedures to expose the heart21. Ocorr et al. developed a technique for measuring characteristics of heart rhythmicity22. These flies must have ventricle cuticle and organs below the dorsally located heart to be removed to create an unobscured recording, and a camera is used to record heart movement from a top-down approach. This algorithm relies on differences in pixel intensity and overall frame brightness to detect changes in heart wall movement. It has been useful in defining the heart rate, systolic and diastolic index, arrhythmicity, and fractional shortening. The heart recordings usually have big data size and repeated measurements from different individuals, which raises a pressing need for generalized computational methods to autonomous processing. Originally, heart beats were counted manually23, which was an incredibly time consuming and less precise technique. Semiautomatic optical heartbeat analysis (SOHA) has been developed by Fink et al.22 and Ocorr et al.21 and upgraded by Monck et al.24 to retrieve the fly heart coherent movement. This method has low implementation cost and can well characterize heart beating, but did not achieve full automaticity and the animals were not intact. Additionally, heart edge-tracing of top-viewing videos has provided pupal heartbeat analysis, as shown by Wessels and Bodmer25.To quantify the cardiac function, the heart region in the OCM videos must be segmented accurately. The heart mask that stores the segmentation over time can be used to calculate dynamic cardiac parameters, such as the heart rate (HR), end-diastolic diameter (EDD), end-systolic diameter (ESD), and fraction shortening (FS), all of which characterize the heart function. For cardiovascular research involving small organisms such as 26. In this method, heart segmentation is generated based on edge detection and principal component analysis. The authors used this technique to quantify heart rate but did not characterize any other parameters. By labeling the full 2D heart cross section in each OCM frame, our noninvasive technique can extract additional information, such as the heart wall velocity and heart area, enabling automatic heart function quantification based on noninvasive techniques like OCM.OCM has then emerged as an important optical method with noninvasiveness and high spatiotemporal resolution. With this imaging method, all developmental stages can be imaged, and larvae and pupae can be returned undamaged for further studies. An algorithmic method has also been employed to analyze OCM M-Mode recordings of heart functionDrosophila heart OCM videos28. To measure the quality of the segmentation, we use the intersection over union (IOU) between the predicted mask and the ground truth provided by human labels. The neural networks described below were all trained on a cropped region of the OCM video that contains the Drosophila heart and has been resized to 128 × 128 pixels. The first iteration of FlyNet, developed in 2018, consisted of a fully convolutional UNet architecture that achieved 85% testing accuracy27. We further developed this model to use convolutional LSTM layers to capture both spatial and temporal information28. FlyNet 2.0 processes whole video sequences, rather than individual frames, improving the segmentation accuracy to 92%. Since the publication of FlyNet 2.0 in 2020, our group has continued to optimize the model: the current version, called FlyNet 2.0+, achieves up to 97% accuracy on high quality videos. This optimized model uses advanced hardware to expand the network size while simultaneously decreasing the training and prediction times. Using an Nvidia RTX 3090 GPU, all 4000 OCM video frames of a beating Drosophila heart can be segmented in 5 seconds, fast enough for real time processing. The unique dataset we present here will enable other cardiac researchers using Drosophila models to increase image analysis accuracy and efficiency while reducing dependence on manual labeling and processing.Our group employs deep learning methods to segment Drosophila cardiovascular research33. The capability of real-time processing will remove previous technical limitations and shorten the waiting interval between batches of experiments. This, along with improved accuracy, will enable new high throughput analysis that does not require human dissection of flies or manual labeling, eliminating the two most time-consuming data analysis steps, reducing human bias in segmentation. Researchers can take advantage of this low latency processing to increase sample sizes which will facilitate new experiments not possible previously.Directly, the development of FlyNet2.0+ can benefit rapid screening, disease modelling and heart disturbance monitoring in Drosophila hearts we collected over the last few years across multiple experiments34. To train a generalized model that can be used for image segmentation and analysis of various physiological conditions we included imaging data of Drosophila at different developmental stages  and with different genetic backgrounds, and, therefore, with different heartbeat dynamics.The dataset presented here contains videos of the beating w*; P{y+t7.7wmC+ = UAS-ReaChR}su(Hw)attP5/+; P{yt7.7+wmC+ = GMR88D05-GAL4}attP2/+ from the cross between stocks #48396 and #53748 (Bloomington Drosophila Stock Center) expressing ReaChR opsin in the heart. Progeny w*; P{yt7.7+wm+C = UAS-eNpHR-YFP}attP2/ P{y[ + t7.7] wmC+ = GMR88D05-GAL4}attP2 from the cross between BDSC stocks #48396 and #41752 expresses NpHR opsin in Drosophila heart. The animals were used in the experiment to mimic cardiac arrhythmias. Here, ReaChR35 and NpHR36 are light-sensitive microbial opsins that can regulate cardiac activities during optical stimulations at specific wavelengths. ReaChR, the red-activatable channelrhodopsin, allows selective depolarization to induce cardiac contraction when expressed heart-specifically, while NpHR, the halorhodopsin from Natronomonas, enables neuronal inhibitions in targeted heart tissue, achieving heartbeat freezing34. y*w67c23 flies were cultured on regular cornmeal fly food; opsin expressing flies were reared on semi-defined fly media containing 1 mM of all-trans Retinal (ATR) to allow the opsins to function properly5.For optogenetic experiments, we obtained progeny w1118; P{GD10318}v25784 males  were crossed to y1w*; P{Act5C-GAL4-w}E1/CyO  females. Progeny P{Act5C-GAL4-w}E1/+; P{GD10318}v25784/+ (adult flies) were selected for the heart functional characterization using OCM. Flies were reared on regular cornmeal fly food.We performed RNAi mediated ubiquitous CG3165 knock down. 2 or FlyNap and mounted, dorsal side up, on a thin layer of rubber cement on a glass slide. Then their wings were spread and stuck down to the glue, using tweezers. The mounting procedure minimized unwanted movement, and the dorsal uppermost positioning allowed unobstructed viewing.The OCM imaging quality is better at larvae and early pupae which have translucent white body cuticle compared to darker late pupae and adult flies, however the higher light absorption in late pupae and adult flies does not hinder segmentation. To mount the larval and pupal stages, the body surface was first brushed clean, then the animals were attached, dorsal side up, to double-sided tape on a glass microscope slide. Adult flies, on the other hand, were first anesthetized with CODrosophila specimens were placed on an adjustable sample stage, with the slide and attached fly specimen oriented longitudinally along the y-transverse direction of the OCM scanning laser, as shown in Fig. Prior to imaging, all mounted OCM recordings of the beating fly hearts are 32 seconds in duration for each measurement. Each recording comprises 4000 frames, with each frame measuring 701 by 128 pixels. These OCM videos are stored in the stacked TIFF file format. Although this full-sized video can be used directly, cropping to closely contain just the heart region can reduce the input size to the FlyNet. No information about the heart is lost, and the reduced data size helps stay within the memory constraints of GPUs. A user can use any cropping software to create a bounding box around the heart region of the video. Data from this smaller region of interest is then extracted and interpolated to a resized 4000 × 128 × 128 video using OpenCV in Python.Next, the resized video is fed through our FlyNet software to predict the 4000 segmentations of the heart region. Each of these segmentations is manually reviewed, and incorrectly classified pixels are corrected manually using segmentation code written in Python to remove areas outside the heart and fill in areas that are blank inside the heart. With this procedure, easily classified frames are processed automatically, and human labeling is required only for challenging scenarios. In this way, we have been able to grow our dataset and iteratively improve the model by correcting misclassified images. After the segmentation mask has been verified as accurate, a separate program converts and interpolates the mask for the resized image to a mask for the full-size image. Each sample has two mask files, a 4000 × 600 × 128 file for the full image and a 4000 × 128 × 128 file for the resized image.22.With an accurate mask, we can finally extract heart parameters. Using the calibration generated for a specific OCM system, we convert pixel numbers to physical measurements. From this, we can calculate the area of one pixel in micrometers and then multiply by the number of pixels in the mask to get the heart area at one time point. When the area is plotted over time, it will fluctuate in a periodic manner, and the time points of the maximum or minimum areas can be analyzed to extract the heart rate. The maximum and minimum areas also identify the end systolic and diastolic phases. From this, fractional shortening is calculated as the percentage difference between the area at the end diastolic and systolic phases. Arrythmia index can be calculated from this as a measure of heart rhythmicity, defined as the standard deviation of the heart rate divided by the median heart rateOCM videos were collected from 112 samples in three developmental stages . To train the neural networks, these samples were split into 80% training, 10% validation, and 10% testing. Further validation was performed on an additional 101 samples. To fully automate the segmentation process, two different neural networks were trained on this data, using TensorFlow. The first neural network, trained on the full-size images, produces a preliminary segmentation to find the heart region of the video. This prediction is used to automatically crop and resize the video to be 128 × 128 pixels centered on the heart. The resized video is fed into the second neural network, FlyNet 2.0+, that was trained on square videos focused on the heart region. This model segments the heart accurately to reliably perform the cardiac analysis described in the Background section.28. Additionally, the training and prediction code was upgraded to take advantage of modern hardware, reduce memory overhead, and speedup processing time. Some major changes to the programs include updating to TensorFlow 2 for newer layers and loss functions, using a generator to load the data in real time, batching the training and prediction code to achieve high utilization while staying within memory limits, and hyperparameter tuning to achieve real-time processing. The model still largely resembles the UNet architecture, with an encoder and decoder bridged together with skip connections, as shown in Fig. FlyNet 2.0+ made multiple improvements to the model architecture but retains many components from past model iterationsTo train FlyNet 2.0+, the Adam optimizer was used, with a learning rate of 0.001. Log-Cosh Dice Loss was chosen because it is a convex function, and because it builds on the Dice Coefficient, a very similar measurement to IOU. To allow for a variety of augmentations during training, a generator was used to load full-size files and apply a unique crop and resize to each 32-frame video sequence. Using the mask for the full-size images, we could ensure that the whole heart was within the frame for each of these different cropping parameters. Before being used to train the neural network and make predictions, each of the videos was centered to have a mean intensity of 0 and a standard deviation of 1.For comparisons of FlyNet 2.0 and FlyNet 2.0+, a two-tail, two-sample z-test for sample means was performed using alpha = 0.05. For CG3165 knockdown experiments, and a two-sided student’s t-test was performed. Results were deemed significant when p < 0.05.figshare and can be downloaded as a zip file37. The file structure of the dataset is shown in Fig. Our dataset is publicly available at To assess the quality of the labeling procedure, a randomly selected set of images was labeled by an expert with no prior predicted mask. Comparing these labels to the traditional procedure of correcting predicted masks allowed us to analyze the model’s influence on label quality. Additionally, these images were labeled on the full-size files, with no interpolation to validate the cropping and resizing procedure. Comparing the expert-labeled masks to the model-corrected masks yielded an IOU score of 88%, demonstrating that the labeling procedure accurately segments the heart. The minute differences in the masks can be attributed to poorly defined boundaries as well as small deviations introduced by the interpolation. As seen in Fig. Additionally, the quality of the segmentations produced by FlyNet 2.0+ further validates the label quality. FlyNet 2.0+ can achieve an average IOU of around 92% and as high as 96%, which is within the same range of variability seen between any two human labelers. In other words, the expert annotator mask, the predicted and corrected mask, and the FlyNet 2.0+ mask are labeling the same heart region. The differences between these masks, small deviations in the boundary of the heart wall, are not significant enough to impact cardiac analysis. Figure For additional comparison, the models were compared in a study of n = 217 image sets with high quality ground truth segmentations. Each image set was predicted on FlyNet 2.0 and FlyNet 2.0+, and the time/frame, overall IOU, and IOU at end systolic and end diastolic points was noted. The IOU comparison in Fig. End systolic Fig.  and end cg3165 RNAi 1 week old adult flies, separated as male and female. Figure To demonstrate the robustness of our model on a dataset that is outside normal cardiac function, we performed analysis of a set of data collected from adult flies where CG3165 protein was ubiquitously depleted by RNAi. OCM monitored heart function and FlyNet 2.0+ provided rapid segmentation for further analysis. We imaged the heart function of control and While this automated labeling technique is powerful, it has some limitations. First, the accuracy of the labels is dependent on high quality OCM recordings. OCM can be prone to visual artifacts and obstructions that can hurt the visibility of the heart. In all developmental stages, the largest area of the heart is used for recording, so the model may not perform as accurately in different regions. Additionally, in the larval stage, movement may occur which obscures the heart region. If the heart is obscured in the recording it can be impossible to produce accurate ground truth labels, making the neural network perform poorly in these situations. We suggest taking multiple repeats of each dataset and fine tuning the recording location to avoid these artifacts.https://imagej.net/software/fiji/) which is an open source and free platform for viewing medical images. The images are saved without any color channels, making both the images and masks grayscale. To overlay the mask on the image, it must first be converted to a color image and then the mask can be added to the red channel. Additionally, saved pixel values are cast to be between 0 and 255 for optimal viewing. Upon loading the images into the Python processing code, masks are converted to be 0 or 1, and the videos are centered at 0 with a standard deviation of 1.To open and view the TIFF files we recommend using ImageJ/Fiji (37.Supplementary videos can be found on figshare


There is a growing interest in the evaluation of tricuspid regurgitation due to its increasing prevalence and detrimental impact on clinical outcomes. Historically, it has been coined the “forgotten” defect in the field of valvular heart disease due to the lack of effective treatments to improve prognosis. However, the development of percutaneous treatment techniques has led to a new era in its management, with promising results and diminished complication risk. In spite of these advances, a comprehensive exploration of the pathophysiological mechanisms is essential to establish clear indications and optimal timing for medical and percutaneous intervention. This review will address the most important aspects related to the diagnosis, pathophysiology and treatment of tricuspid regurgitation from a cardiorenal perspective, with a special emphasis on the interaction between right ventricular dysfunction and the development of hepatorenal congestion. RighTR can lead to dysfunction of the right ventricle (RV) due to increased preload and progressive remodeling. This consequently results in signs and symptoms of heart failure (HF) and subsequently contributes to a spectrum of liver and kidney impairment –5 primarTR has long been considered a relatively benign entity resulting in the underutilization of diagnostic and therapeutic resources. The underestimation of the clinical impact of TR has led to a pattern of care delaying intervention until very advanced stages of disease where the risks of treatment become excessively elevated . While s2.TR is frequently encountered in the echocardiography laboratory. While mild TR may not have significant consequences, advanced degrees of TR are associated with factors such as advanced age, female sex, and left sided heart disease. Moderate to severe TR is present in 4%–6.6% of patients older than 75 years and is associated with increased mortality and morbidity independent of RV dysfunction and pulmonary hypertension , 2.Primary TR is the least prevalent etiology, representing only 8%–10% of all TR cases and is mainly related to pathologies affecting the tricuspid apparatus  and tricuspid valve (TV) leaflets. Causes of primary TR include carcinoid syndrome, rheumatic heart disease, congenital abnormality of TV, iatrogenic valve damage and endocarditis. Lead impingements from cardiac implantable electronic devices are a leading cause of primary TR, as it has been reported to occur in up to 38% of patients following implant –11.Secondary TR can arise as a consequence of various factors, including RV dilatation due to volume overload or increased pulmonary pressures. It may also result from dilatation of the right atrium or tricuspid annulus as occurs in atrial fibrillation. Additionally left heart or valvular diseases can contribute to the development of secondary TR. Interestingly, 8% of cases of secondary TR can occur in isolation . In the Transthoracic echocardiography (TTE) is the preferred diagnostic method for TR, allowing TV visualization as well as RV function . Despite3.The impact of TR on the RV varies on a number of factors including the underlying cause, degree of anatomical alteration, presence of pulmonary hypertension, left valvular heart disease or presence of atrial fibrillation (AF) , 16. SevAs in the case of TR, TTE remains the primary imaging modality for RV assessment, for practical reasons. Conventional TTE parameters such as tricuspid annular systolic excursion (TAPSE), tissue Doppler velocity at the lateral tricuspid annulus and fractional area change rely on geometric assumptions and are load and angle-dependent leading to an overestimation of RV function in severe TR . Other p4.TR causes an elevation of RV preload leading to a decrease in cardiac output, and an increase in venous congestion. Consequently, signs and symptoms of right heart failure (RHF) include an elevated jugular venous pressure, edema, ascites, hepatomegaly and, in advanced stages, renal and hepatic failure with malnutrition . Congest4.1.2 . If liver damage progresses, increased serum aminotransferase, hypoalbuminemia and coagulopathy can be seen. Liver disease can become as clinically relevant with progressive cardiac disease which further complicates its management –39.4.3.The relationship between HF and the gastrointestinal system is complex and not yet fully understood. RV dysfunction has been linked with malabsorption, loss of appetite and weight loss, often culminating in the development of cardiac cachexia. Splanchnic congestion, a hallmark of RV dysfunction, exerts changes on gut morphology, permeability, and function. These alterations can result in changes in the composition of the gut microbiota, potentially impacting processes like bacterial translocation and activation of inflammatory pathways .5.When evaluating congestion in TR, it is crucial to employ diverse diagnostic methods. These may encompass clinical scoring systems, imaging techniques, bioimpedance measurements, hemodynamic tests, and analysis of circulating biomarkers.5.1.The Venous Excess Ultrasound Score (VExUS) is a valuable tool for assessing a patient's volume status through point-of-care ultrasound , 42. TheWhile ultrasound volume assessment is at times considered less informative in patients with TR due to its association with elevated right atrial pressure, it is important to recognize that patients with TR can still experience clinical overload, even without absolute excess volume. Therefore, severity indicators identified through ultrasound warrant careful consideration, especially those unaffected by right atrial pressure, such as the Doppler portal vein pulsatility index and the intrarenal veins waveform, as they reflect right-sided heart hemodynamics. It is worth noting that while portal Doppler remains unaffected by right atrial pressure, a false negative interpretation can occur in the setting of liver cirrhosis due to centrilobular fibrosis. Therefore, a scenario of a seemingly normal pattern (pulsatility <30%) can mask hepatic congestion . In TR, 5.2.In patients with right heart failure (RHF), particularly those with significant TR, natriuretic peptides may not provide additional prognostic information as their levels tend to be lower than in patients with reduced left ventricular ejection fraction. Alternatively, CA-125, a glycoprotein synthetized by serous epithelial cells, has been found to better reflect right heart function and may have a stronger predictive value in RV failure and venous congestion. CA-125 concentrations are not influenced by factors like renal function, age, or weight –47. Anot6.6.1.The evidence for guideline-directed medical therapy for TR is lacking. There is a limited armentarium in treatment options beyond addressing the underlying causes of secondary tricuspid regurgitation and diuretics (Class IIa indication in the 2022 European guidelines) . Loop di6.2.In contrast to left-sided HF, the evidence supporting the use of standard HF medications other than diuretics for the right side is not well established and may vary according to the underlying cause and the acute or chronic presentation. Inotropes can be used to support RV function and optimize left ventricular filling pressures. Levosimendan and milrinone may be of particular interest due to their pulmonary vasodilatation properties, that would diminish RV afterload , but car6.3.Isolated surgery for severe TR has a class IIa indication in symptomatic patients, however, it is limited by its high in-hospital mortality rate. As an alternative, percutaneous interventions have emerged for inoperable or very high-risk patients, with a Class IIb indication in the recent European guidelines .1)Coaptation devices: these include leaflet approximation with tricuspid transcatheter edge-to-edge repair (T-TEER) or spacers devices, whose objective is to increase leaflet coaptation. Initial experience with T-TEER systems have shown potential benefits in observational trials, including a decrease in hospitalizations for HF , increas2)n = 61) and showed a sustained reduction of TR (69% grade II or lower), reduction in annular diameter, inferior vena cava diameter and early evidence of right heart remodeling 1 month after implantation  system facilitates a percutaneous annuloplasty, reducing the diameter of the tricuspid anulus to facilitate leaflet coaptation. It was evaluated in the TriBAND study (3)Heterotopic caval valve implantation: this approach aims to reduce retrograde cava flow and hepato-renal congestion in patients with unacceptable surgical risk who are refractory to medical treatment and unsuitable for T-TEER with initially promising results .4)Transcatheter orthotopic valve implantation: this involves replacing the TV with a transcatheter valve. Preliminary data of the TRISCEND trial has been published regarding the EVOQUE system , a transcatheter valve that replaces the TV:TR was reduced to mild or less in 98% of the patients and there was a significant improvement in symptoms 30 days after the procedure .While device therapy is rapidly evolving, more randomized trials are needed to allow us to select the right population and optimal timing for each device.Percutaneous intervention for TR includes a range of devices:7.TR is highly prevalent, particularly when associated with left heart disease and among vulnerable populations such as women and the elderly. Although it has been historically overlooked, TR is associated with a 65% increase in hospitalizations and death, a risk that is even higher in patients with RV dysfunction. Diagnosis is made by TTE (2D and 3D). RV assessment by TTE is more challenging in the presence of severe TR.Clinical manifestations of TR revolve around signs of abdominal congestion, which bear prognostic implications even when mild . A comprIn the recent years, several percutaneous treatment techniques have emerged, with different mechanistic approaches, showing promising safety profiles. However, there remains limited evidence regarding their clinical and prognostic impact, and more importantly their appropriate indications. More advanced patients may benefit less from the therapy, therefore identifying optimal timing for these interventions becomes a crucial element . Further


Conduction system pacing (CSP) has evolved rapidly to become the pacing method of choice for many adults with structurally normal hearts. Studies in this population have repeatedly demonstrated superior hemodynamics and outcomes compared to conventional pacing with the recruitment of the native conduction system. Children and patients with congenital heart disease (CHD) are also likely to benefit from CSP but were excluded from original trials. However, very recent studies have begun to demonstrate the feasibility and efficacy of CSP in these patients, with growing evidence that some outcomes may be superior in comparison to conventional pacing techniques. Concerns regarding the technical challenges and long-term lead parameters of His Bundle Pacing (HBP) have been overcome to many extents with the development of Left Bundle Branch Area Pacing (LBBAP), and both techniques are likely to play an important role in pediatric and CHD pacing in the future. This review aims to assimilate the latest developments in CSP and its application in children and CHD patients. Over the past 5 years, the advancement of conduction system pacing (CSP) in the management of adult patients with structurally normal heart has been exponential. However, the use of this technology in pediatric and congenital heart disease (CHD) patients has been limited. As is commonly observed in the development of new techniques, fewer patients, younger age at implant and increased patient complexity have inhibited early adoption or inclusion in prospective clinical trials. This review aims to summarize the pertinent and applicable findings in the adult (non-CHD) literature, as well as the limited pediatric and CHD reports of CSP. In this way we aim to provide a platform for the clinician working in the pediatric/CHD field to make an informed decision regarding the merits of CSP in this important patient population.There are currently two main forms of CSP: His Bundle Pacing (HBP) and Left Bundle Branch Area Pacing (LBBAP), with multiple subdivisions within each type. . HBP is HBP was demonstrated as early as 1970, with the first pacing system implant demonstrated in 1992 in canines. . The firversus 0.4% in one large study). , with a long learning curve and persistent 10%–20% HBP system implant failure rate, despite the increasing involvement of device manufacturers in optimization of lead and catheter design. . This is study). . In the In this context, the concept of LBBAP has developed rapidly as it has a shorter learning curve, superior medium-term  lead parameters and higher rates of successful implant. The technique was first formally described by Pediatric and CHD patients are at risk of cardiomyopathy either secondary to long-term pacing or cardiac dyssynchrony, secondary to existing conventional  pacing or inherent conduction disease. Traditional biventricular pacing (CRT) has been used with some success in these scenarios , but theIn the structurally normal heart, it is well-established that higher conventional right ventricular pacing (RVP) ventricular pacing percentage (Vp) is associated with increased risk of deterioration in systemic ventricular function, heart failure (HF) and death. . Animal However, the majority of paced patients are subjected to decades of pacing-induced dyssynchrony and never develop pacing induced cardiomyopathy (PICM). Estimates of incidence depend in part upon duration of follow-up (and definition of PICM), but are generally around 10%–20%. One of the larger studies included 823 consecutive patients with RVP and normal baseline function: 101 (12.3%) developed PICM over a follow-up of 4.3 ± 3.9 years. It has been shown that there are factors that pre-dispose to PICM such as male sex, wider QRS duration (native and paced) and higher Vp percentage, but these predictors are relatively weak and many of the determinants of the vulnerability to PICM remain unidentified.Lead positioning has been studied as a potential risk factor for later development of PICM. Epicardial LV apical lead placement has been shown to decrease the likelihood of developing PICM. . Initialversus single site CRT.  in the adult population, with demonstration of resynchronized ventricular activation. Initially CSP was described as a bail-out strategy when conventional multisite CRT could not be achieved or failed, but CSP may also be employed as a primary CRT strategy. . Furtherite CRT. .p = 0.03). . . It is lGiven the rapid evolution of CSP, guidelines are generally lagging behind clinical practice in non-CHD adults. The 2018 ACC/AHA/HRS bradycardia and conduction delay pacing guidelines endorse HBP specifically (or CRT) in patients with AV block and an indication for permanent pacing, especially if anticipated Vp>40% (Class 2A). . The 202For the pediatric and CHD population, the 2021 Pediatric CIED guidelines deliberately made no mention of CSP as recommendations for this patient group will also be included in the 2022 HRS/APHRS/LAHRS guidelines on physiological pacing. . For theThe technique and equipment required for HBP in the adult with structurally normal heart is described in detail elsewhere. . In geneThe His Bundle (HB) is generally interpreted to be the part of the conduction system that lies between the AV node and bifurcating AV bundle . Some suIn the pediatric patient with a structurally normal heart, the location of the proximal His Purkinje system is conventional, albeit that the smaller dimensions in children may be less amenable to lead delivery using standard sheaths such as the Medtronic  C315H sheath (see below). However, the location of the His Purkinje system is clearly much more varied in patients with CHD. In simpler forms of CHD, such as an isolated VSD, the variation from normal is less marked, although the non-branching portion of the HB tends to be longer in those with perimembranous VSDs such as in tetralogy of Fallot. With increasingly complex CHD, the displacement of the AV node and HB becomes more marked. For example, in those with AVSD, the AV node is displaced postero-inferiorly, and in ccTGA (with situs solitus) the AV node is displaced anterosuperiorly with the long HB descending in the anterior portion (or “crest”) of the ventricular septum. .The majority of HBP in pediatric and CHD described in the literature has used Medtronic leads and sheaths. The 4.1Fr Medtronic 3830 has demonstrated good lead characteristics for implant with the narrow profile, catheter-based delivery system and fixed helix screw. In addition, there is longer-term lead robustness data available, including in the pediatric cohorts. . The leaThe Medtronic C315H sheath is the most commonly used delivery sheath for HBP. It has a 7Fr outer diameter, 43 cm usable length and 79 mm/43 mm horizontal/vertical reach. It was designed for access from the left-sided device implant site to reach RA and RV septal locations, but can also be reshaped to a degree for right-sided implants, smaller patients or abnormal anatomy. . MedtronOverall, in a recent multicenter study of CSP in CHD, 14 out of the 17 HSP were performed using the Medtronic C315H catheter, with only one utilizing the steerable C304H sheath. . Again, Lead delivery is generally performed from the left side when venous access is available. However, in patients with a previous atrial switch operation and those with dextrocardia, some centers have deliberately chosen right‐sided venous access for better sheath orientation against the interventricular septum. .HBP in pediatric and CHD patients is generally performed with the assistance of mapping tools. In a multicenter study including 17 CHD patients with HBP, 16 (94%) were performed using 3D mapping for guidance. . The appFor precise placement of the lead, mapping is performed in a unipolar fashion, with many choosing to display the signal on an electrophysiology recording system as well as at the pacing system analyzer. . When a A further consideration in pediatric implants is the degree of lead slack. Adult studies have noted increased rate of lead dislodgment or late rises in threshold with excessive HBP lead slack. . Therefoversus non-selective (NS-HBP) have been defined, and it is reasonable to extrapolate those same criteria to pediatric and CHD patients. (Identification of the type of HBP achieved is dependent upon recognition of the QRS morphology at varying outputs. Clear criteria for selective (S-HBP) atients. . NS-HBP,atients.  is generatients. . It shouThe evidence for the risks and benefits of a backup RV lead are well-delineated in the 2021 ESC pacing and CRT guidelines. . A backup <0.001). A backup RV lead was not reported to have been implanted in any case, and there were no severe complications related to loss of HSP capture in either study.In the pediatric and CHD population, chronic rises in pacing lead thresholds have also been demonstrated and are generally in line with those reported in prior studies in non-CHD populations. . Moore eSimilarly in congenital complete heart block (CCHB), there is generally a more robust underlying heart rhythm than in post-surgical iatrogenic CHB, and a backup RV lead has generally not been implanted in adults with CCHB. .The pediatric experience in HSP is summarized in versus 1.1 ± 0.3, p = 0.014). Notably, the SVEF in the PICM group improved from 26% ± 15% to 48% ± 3%.There is also important and relevant data in a multicenter report of pacing of CCHB by However, two patients required revision of the HBP lead due to elevated pacing thresholds.The potential impact of surgical scarring near the conduction apparatus, and the variation in the underlying anatomy of the conduction system, have been raised as barriers to HBP in the CHD population. There is also a suggestion that those with CHD may be more prone to distal His Purkinje injury, and hence may not be able to achieve such a narrow QRS even with optimal lead placement. .The 2022 (non-ccTGA) multicenter study by Moore and others included 17 HBP systems in CHD patients, all of whom had biventricular circulation with systemic LV. TOF or VSD represented the commonest underlying CHD and in the majority the indication for pacing was AVN block, with only one implant for CRT alone. Nine (53%) systems were S-HBP, and 8 (47%) were NS-HBP. Again, there were no significant complications, but a rise of the ventricular pacing threshold to >2 V was documented in 3 (18%) patients. .In a separate study of CSP in patients with uncorrected ccTGA, 11 out of 13 patients had HBP performed. The distal His bundle and proximal left bundle branches were identified within the morphologic left ventricle below the pulmonary valve, separate from the mitral annulus , and medLBBAP is defined as the capture of either the proximal left bundle or one of its fascicles at a low threshold, usually also with septal myocardium capture at low output. . The tecThe anatomical location of the LBB is closely tied to that of the distal HB, and similar considerations apply. . HoweverPre-implantation imaging should be reviewed to ascertain the thickness of the proximal septum and best estimate of location of the proximal LBB. The site of deployment of the LBBAP lead is generally performed empirically given the wider target for pacing. However, in some reported CHD cases, different techniques for site identification have been deployed. These include placement of a quadripolar mapping catheter across the HB to delineate the distal extent of His electrograms , RV angiPacing system equipment for LBBAP is similar to that employed for HBP. In The successful LBBAP site is classically reported to be 1–1.5 cm below the distal HB, along a line connecting the HB to the RV apex in RAO view. More recent data suggests that many operators are achieving capture at slightly more distal sites , 1.5–4.5 cm distal to the His. . In the Once the site for deployment is selected, there are two main methods of guidance of lead delivery: gradual screwing-in of the lead with monitoring of paced QRS morphology and unipolar impedance, or rapid screwing-in with monitoring of PVC morphology. All data regarding these techniques is isolated to adults with structurally normal hearts. . Howeverversus LBB) may also be used to prove LBB capture, using either a basic drivetrain or sensed extras.  or “R Wave Peak Time” (RWPT): the former term is more widely employed, while the latter is arguably more physiologically accurate. In adults without LBBB, an LVAT≤75 ms is both sensitive and specific for LBB capture (≤85 ms in LBBB). Acceptable values in pediatric and CHD have not been established, but appear to be slightly shorter in children. In a study including 12 children with LBBAP, In CHD patients, it is likely that identification of the LBB may prove more challenging as the field evolves to include ever more complex patients. In this setting, LVSP may often be achieved, and it remains to be proven that this is significantly worse in terms of hard outcomes in comparison to LBB pacing. LVSP is typically defined as when LBB capture criteria are not met, but a deep septal position may be visualized with contrast and there is a significant reduction in the QRSd (or QRS≤130 ms). .via the C315 S4 or HIS sheath in the LAO view.The largest published study of pediatric LBBAP is by There is growing experience of LBBAP in CHD. One particular area of interest relates to the application of LBBAP to patients with systemic right ventricles. There are two main groups: those without operative anatomic correction of ccTGA  and those with d-TGA post atrial switch. In the ccTGA patient, there remain concerns regarding both the efficacy and safety of pacing the superficial and relatively exposed LBB. LBBAP results in continued delayed transseptal activation, and the long-term viability of the vulnerable His Purkinje system has not been proven. Therefore, RBB area pacing has been proposed (burrowing across the septum to reach the RBB on the left side) and performed with good initial results in a small subset of three patients. . SimilarCSP is a relatively new technique, and the data on which to base the decision as to whether to perform CSP in pediatric/CHD is limited. The data is even more limited for LBBAP, and therefore decisions for CSP modality are likely to evolve rapidly.HSP is backed by the greater evidence for short term efficacy and safety, has a lower risk of perforation, and better data on feasibility of extraction (see below). However, there remain concerns regarding lead longevity and reliability, particularly in the context of implants for AVB in the majority of the pediatric/CHD population. Recent data from a single study of CSP following AV nodal ablation  demonstrated reassuringly similar safety outcomes in both HBP and LBBAP groups, but with inferior lead parameters in the HBP cohort. .Perhaps the greatest determinant of CSP modality in the long term in pediatric and CHD will be the difference in learning curves. In contrast to adult electrophysiology, even the largest pediatric and CHD centers rarely perform over 50 device implants per year. It has been suggested that approximately 40 implants are required for the learning curve to begin to plateau for HBP, with substantially smaller number of implants required to learn LBBAP techniques. .versus LBBAP in the adult population.  of respondents anticipated that CSP would dominate bradycardia pacing in the future. . No suchHOT-CRT and LBBAP-optimized CRT clearly may also play a role in those with more conventional cardiac arrangements and CS anatomy. However, the greatest challenges, and gains, in implementation of CSP for CRT arises in the more complex anatomies or physiologies. In particular, minimization of dyssynchrony of the single ventricle is increasingly recognized to be important for long-term survival. . Future Finally, dyssynchrony of the right ventricle has also been recognized to have substantial impact upon the function of both ventricles, such as in ToF. Permanent HBP in patients with RBBB has been demonstrated to be associated with significant narrowing in the QRSd and improvement of LV function, and therefore this area warrants further exploration. . It is lThe adoption of conduction system pacing for adults with structurally normal hearts has evolved rapidly over the past 5 years, with growing evidence of safety and improved outcomes in comparison to conventional pacing modalities. For children and patients with congenital heart disease, the potential benefits of CSP are even more substantial, but this must be weighed against increased procedural complexity and possible increased risk in these patient cohorts. Most recently, there has been a shift from His bundle pacing towards left bundle branch area pacing, and pediatric/CHD-specific publications are now creating a greater evidence base for CSP. Continued work is required to delineate the role that CSP has to play in the future, but work in the structurally normal heart suggests that the use of CSP in pediatrics and CHD is likely to grow rapidly.


Background and aim: The presence of mechanical dyssynchrony on echocardiography is associated with reverse remodelling and decreased mortality after cardiac resynchronization therapy (CRT). Contrarily, myocardial scar reduces the effect of CRT. This study investigated how well a combined assessment of different markers of mechanical dyssynchrony and scarring identifies CRT responders. Methods: In a prospective multicentre study of 170 CRT recipients, septal flash (SF), apical rocking (ApRock), systolic stretch index (SSI), and lateral-to-septal (LW-S) work differences were assessed using echocardiography. Myocardial scarring was quantified using cardiac magnetic resonance imaging (CMR) or excluded based on a coronary angiogram and clinical history. The primary endpoint was a CRT response, defined as a ≥15% reduction in LV end-systolic volume 12 months after implantation. The secondary endpoint was time-to-death. Results: The combined assessment of mechanical dyssynchrony and septal scarring showed AUCs ranging between 0.81 (95%CI: 0.74–0.88) and 0.86 (95%CI: 0.79–0.91) for predicting a CRT response, without significant differences between the markers, but significantly higher than mechanical dyssynchrony alone. QRS morphology, QRS duration, and LV ejection fraction were not superior in their prediction. Predictive power was similar in the subgroups of patients with ischemic cardiomyopathy. The combined assessments significantly predicted all-cause mortality at 44 ± 13 months after CRT with a hazard ratio ranging from 0.28 (95%CI: 0.12–0.67) to 0.20 (95%CI: 0.08–0.49). Conclusions: The combined assessment of mechanical dyssynchrony and septal scarring identified CRT responders with high predictive power. Both visual and quantitative markers were highly feasible and demonstrated similar results. This work demonstrates the value of imaging LV mechanics and scarring in CRT candidates, which can already be achieved in a clinical routine. Cardiac resynchronization therapy (CRT) is indicated in patients with symptomatic heart failure, reduced left ventricular (LV) ejection fraction LVEF ≤ 35%), and a wide QRS ≥130 ms), preferably with a left bundle branch block (LBBB) morphology. Despite technical improvements and accumulating experience, the non-response rate to CRT remains high circa 30–40%) 30 ms, pr. More th5%, and a0% 30 ms,Since then, a better understanding of the pathophysiology has led to the identification of motion patterns that truly reflect a curable substrate for CRT ,9,10,11.In contrast, both the extent and location of myocardial scar influence myocardial motion patterns and have a negative impact on CRT outcome ,14. ReceThe present prospective multicentre study investigated the impact of myocardial scarring on the prediction of a CRT response using an echocardiographic evaluation of mechanical dyssynchrony. Cardiac magnetic resonance imaging (CMR) with late gadolinium enhancement (LGE) was used to assess myocardial scarring. The primary endpoint was volumetric reverse remodelling at 12 months follow-up. The secondary endpoint was long-term survival. The combined approach of integrating information of myocardial scarring with mechanical dyssynchrony was: (I) compared among both visual (SF/ApRock) and quantitative (SSI/LW-S work difference) markers, (II) evaluated for its additive predictive value over those markers alone, and (III) tested for its added value over LV ejection fraction, QRS duration and morphology.A total of 200 heart failure patients referred for CRT were prospectively recruited through the cardiology departments of the University Hospitals Leuven, Belgium; Oslo University Hospital, Norway; CHU Rennes, France; and OLV Hospital Aalst, Belgium between August 2015 and November 2017. The patients were all-comers with an indication for CRT, according to the European Society of Cardiology guidelines, at the time of inclusion . ExclusiEchocardiography was performed within 1 week before and 12 months after CRT implantation, using Vivid E9 or E95 ultrasound scanners . Blood pressure was measured using the brachial cuff method at the beginning of the examination. LV volumes and LVEF were measured using the modified Simpson’s biplane method. Regional and global longitudinal strains (GLSs) were measured by speckle tracking (frame rate > 60 frames/s) using the 18-segment model. All analyses were performed offline using EchoPAC version 202 (GE Vingmed).Visual assessment of SF was performed in the apical four- and three-chamber view. SF was defined as a rapid inward motion and shortening of the (antero-)septal wall, occurring directly after the onset of QRS and before shortening of the lateral wall . Presence of SF was recorded if it was seen in either the four- or three-chamber view, or both.Visual assessment of ApRock was performed in the apical four- and three-chamber view. ApRock was defined as a systolic septal-to-lateral motion sequence of the apical myocardium . The laterally directed component should occur during ejection time, i.e., before mitral valve opening. The presence of ApRock was recorded if it was seen in either the four- or three-chamber view, or both.Three readers in Leuven  performed independent visual readings of SF and ApRock prior to CRT implantation. At the time of the reading, these observers were blinded to all patient information. Mechanical dyssynchrony was considered present when either SF or ApRock, or both, were observed. For further analysis, the majority opinion of the three readers was used.SSI was calculated from longitudinal strain traces of the four-chamber view as the sum of the septal systolic stretch and lateral systolic pre-stretch before aortic valve closure  . LGE images were obtained as previously described . Scar sin = 42) and severely reduced renal function (n = 11). For the remaining patients (n = 22), reasons included claustrophobia, intracranial metal implants, and logistic causes.LGE-CMR was obtained in 125 of 200 patients. The main reasons for the other 75 patients not undergoing LGE-CMR were non-CMR-compatible devices (In patients without LGE-CMR (75 of 200), the presence of large myocardial scarring was excluded based on all of the following: (I) no evidence of a previous myocardial infarction in the medical history, laboratory values, ECG, or scintigraphy; (II) no relevant stenosis on a recent coronary angiogram (max. 1 year prior to CRT implantation); and (III) no history of coronary intervention . In 30 of 75 patients without CMR data, scarring could not be ruled out. These patients were excluded.Patients underwent standard implantation of a biventricular pacing system. Coronary venography was used to optimize the placement of the LV lead in a lateral or posterolateral vein. The device was programmed in a conventional biventricular pacing mode and retested prior to hospital discharge.Primary endpoint was CRT response, defined as a ≥15% reduction in LV end-systolic volume at 12 months follow-up. All volumes were measured independently in three different centres  by readers blinded to any other data . Reported volumes are the averages of the three readings. Volumetric CRT response (yes/no) was determined based on a majority decision.Secondary endpoint was time-to-death of any cause, heart transplant, or LV assist device implantation, with an average follow-up time of 44 ± 13 months after CRT implantation (median 1543 (IQR 139–1726) days).t-tests or chi-squared tests were used for comparison of continuous or categorical variables, respectively. Univariate or multivariate linear regression analysis was used to identify predictors of reverse remodelling. Collinearity was tested using the variance inflation factor (VIF). Receiver operating characteristics (ROC) curves with area under the curve (AUC) values were used to determine the discriminative ability. To combine the assessment of two or more parameters, logistic regression was used to calculate a linear combination of parameters, the equation of which was then used for ROC curves. Nagelkerke’s R2 was reported for the predictive value of multivariate logistic regression models. The Delong method was used to compare ROC curves. Survival data are presented as hazard ratios (HR) (Cox regression) and Kaplan–Meier curves with a log-rank test for comparison. Inter-rater variability was tested using intra-class correlation (ICC) by two readers blinded to any other data . Statistical significance was set at a two-tailed probability level of p < 0.05. Missing data were handled using pairwise deletion per parameter.Analysis was performed using SPSS Statistics 20  and MedCalc 15 . All continuous variables are expressed as mean ± standard deviation if normally distributed, otherwise by median ± interquartile range. Normality was assessed using the Shapiro–Wilk test. (Un-)paired sample Of the 170 included patients, 2 patients had died and 1 underwent heart transplantation, before 12 months follow-up. These three patients were considered as non-responders. The primary endpoint of the ≥15% reduction in LV ESV was achieved in 121 patients (72%). Among non-responders were more patients with ischaemic cardiomyopathy . At follp < 0.0001). Regression analysis revealed a direct relation between the presence of SF or ApRock (R = 0.51), SSI (R = 0.46), and LW-S work difference (R = 0.41) vs. reverse remodelling .Prior to CRT, 119 (70%) patients showed either SF or ApRock, 117 (69%) patients had an SSI ≥ 3.1%, and 115 (68%) patients demonstrated LW-S work asymmetry ≥ 860 mmHg·% . These mp < 0.0001) (p > 0.05), but both were higher compared to SSI .The AUCs were 0.73 for the presence of SF or ApRock, 0.67 for SSI, and 0.76 for LW-S work difference  . The pren = 148), the AUCs were similar and ranged between 0.69 and 0.76   . The echIn multivariate linear regressions, SF or ApRock, SSI, and LW-S work difference, together with ischemic/non-ischemic aetiology, but not QRS morphology (LBBB or non-LBBB) nor QRS duration or LVEF, were independent predictors of volumetric change after CRT .p < 0.0001). Multivariate linear regression, including the percentage of anterior, septal, inferior, and lateral wall scarring, revealed that only septal scarring was a significant predictor of reverse remodelling (p < 0.05).Scarring was present in 58 (34%) patients. In total, 43 patients (25%) had some degree of scar in the anterior wall, 54 (32%) in the septum, 52 (31%) in the inferior wall, and 36 (21%) in the lateral wall. Univariate linear regression showed an inverse correlation between the percentage of LV scarring and reverse remodelling . QRS morphology, QRS duration, and LVEF were not predictive .In multivariate linear regressions, only markers of mechanical dyssynchrony and septal scarring remained independent predictors of reverse remodelling after CRT   , all AUCs were significantly better than the markers of mechanical dyssynchrony alone . When analysing patients with LBBB only (n = 148), the AUCs were similar and ranged between 0.82 and 0.85  . While tand 0.85 .p < 0.01) (The combined approaches were strong and significant predictors and the reduced risk of death at 44 months follow-up . Further < 0.01) .The predictive power of the combined assessments for a CRT response was similar in the subgroups of patients with and without ischaemic aetiology of cardiomyopathy . AUCs raThe average ICC between the three centres for assessing the presence of reverse remodelling (delta ESV) at 12 months was 0.87 (95%CI: 0.81–0.91). Inter-rater agreement of the tested variables was good, with ICC = 0.73 (95%CI: 0.69–0.81) for SF or ApRock, ICC = 0.71 (95%CI: 0.62–0.78) for SSI, and ICC = 0.82 (95%CI: 0.76–0.87) for LW-S work.Data from this prospective, multicentre study demonstrate that combining the assessment of mechanical dyssynchrony using echocardiography with information on myocardial scarring improves the accurate identification of patients who will respond to CRT with reverse remodelling and who have better long-term survival after CRT. Septal wall scarring was shown to significantly affect CRT response predictions by mechanical dyssynchrony, as well as survival. The predictive power of a combined assessment, including information on septal scarring, was significantly stronger than that of mechanical dyssynchrony alone—independent of using either visual (SF/ApRock) or quantitative markers (SSI or LW-S work difference)—with no difference among the markers. Lastly, both the presence of mechanical dyssynchrony and septal scarring were stronger predictors of CRT responses when compared to LV ejection fraction, QRS duration, and morphology.SF, ApRock, SSI, and LW-S work differences are features specific to mechanical dyssynchrony in CRT candidates, which have already been shown to predict response and long-term survival after CRT in other prospective studies ,11,13. HIn the present study, scarring in the septal wall proved to be the strongest scarring determinant of non-response after CRT, among the different LV regions, including the lateral wall. Notably, the deformation pattern of a scarred septum can be very similar to a remodelled and dyssynchronous septum in LBBB, which is dysfunctional but viable. In this scenario, information on septal scarring provides an added predictive value in a multivariate analysis as it helps to distinguish both situations ,15. As aFurthermore, while the predictive power of the combined assessments towards CRT response appears similar between patients with or without ischemic heart disease, it provided a high sensitivity in non-ischemic patients  and a high specificity in ischemic patients  .In the past years, evidence has accumulated that mechanical dyssynchrony is the fundamental pathophysiologic principle that leads to remodelling in conduction delays such as LBBB and that imaging dyssynchrony can better identify patients who could benefit from CRT. Besides the visual assessment of SF and ApRock, a multitude of quantitative parameters has been proposed, with two promising candidates being SSI  and LW-SAn important advantage of markers of mechanical dyssynchrony is their feasibility in clinical routine; they can be easily obtained either visually or by a routine speckle-tracking-based analysis, which is feasible in nearly all CRT candidates . Furthermore, the inter-rater agreement in our study was high.The present multicentric prospective study adds to the evidence that assessment of mechanical dyssynchrony and scarring by imaging can reliably, and relatively simply, identify CRT candidates. Furthermore, it highlights that a better understanding of the mechanisms of dyssynchrony also allows a better clinical judgement. The presence of SF or ApRock can be determined easily on echocardiographic apical images in nearly all patients. SSI and LW-S work differences are based on speckle-tracking analysis, which has become clinical routine in recent years. Scar assessment by CMR is of course an additional burden. However, a majority of centres already perform LGE-CMR as a routine investigation prior to CRT to avoid LV lead placement in a scar.In a substantial number of patients, LGE-CMR is not feasible due to, e.g., severely reduced renal function or a previously implanted device. Wider use of renal-saving contrast agents and CMR-compatible devices will be helpful. The use of nuclear scintigraphy as an alternative option for assessing scarring is limited due to its high cost and patients’ exposure to ionizing radiation .Ruling out myocardial scarring based on patient history and coronary angiogram has the limitation of disregarding (particularly) scarring of non-ischemic origin, which can also affect the CRT response .Myocardial work analysis is currently only available from one vendor. Future developments could expand this methodology to other vendors.Data on the LV lead position were not available and may have provided additional insights.Even though evidence on the clinical use of mechanical dyssynchrony as a CRT indicator has already been demonstrated in multiple  trials, solid evidence from randomized controlled trials is needed if imaging-based selection criteria are to be included as guideline indications .The present study shows that readings of mechanical dyssynchrony—combined with an assessment of septal scarring—prior to CRT implantation have an added predictive value regarding reverse remodelling and long-term survival, compared to mechanical dyssynchrony alone. Patients with the presence of mechanical dyssynchrony on echocardiography—shown by either SF, ApRock, high SSI, and high LW-S work difference—are most likely to respond and survive in the long term after CRT. However, when septal scarring is present on CMR, this likelihood is reduced. This work adds to the building evidence on the value of imaging LV mechanics and scarring in CRT candidates, which can already be achieved in clinical routine.


Both FLC and FTC were significantly lower in the Degenerated RV and Constricted RV groups compared with those in the Control and Overloaded RV groups. The T/L ratio was significantly lower in the Degenerated RV group (p = 0.008), while the Overloaded RV (p = 0.986) and Constricted RV (p = 0.582) groups had preserved T/L ratios, compared with the Control group. Transverse shortening contributes to RV function more significantly compared with longitudinal contraction. Impaired T/L ratios may reflect RV myocardial degeneration. RV fractional parameters may help precisely understand RV dysfunction.Studies of the usefulness of transverse right ventricular (RV) shortening are limited. We retrospectively analyzed the CMR images of 67 patients : n = 15, Constricted RV (pericarditis): n = 17, Degenerated RV (arrhythmogenic right ventricular cardiomyopathy): n = 15)  in a single center. We defined RV longitudinal  and transverse  contraction parameters. We assessed the FTC/FLC (T/L) ratio on four-chamber cine CMR views and compared the four groups regarding the fractional parameters. FTC had a stronger correlation (R CMR enables visualization of a complete four-chamber view without deficits, while echocardiography sometimes fails to visualize the part of the RV free wall that is located near the rib cage. However, RV volumetric assessment by CMR requires certain equipment and intensive labor for segmentation4. Therefore, clinically, RV volumetric assessment by CMR is difficult to perform routinely.Cardiovascular magnetic resonance (CMR) imaging is becoming an increasingly important tool in routine clinical practice, and this imaging is being applied for right ventricular (RV) volumetric assessment as the gold standard5. In contrast, in subjects with structural abnormalities in the RV, etiology-specific shortening patterns  have been reported rarely. Currently, the evaluation of strain assessment on CMR using feature tracking is increasing in clinical practice6. RV longitudinal strain has prognostic importance in various cardiac diseases7. Furthermore, while the clinical application of RV circumferential strain appears to be limited compared with that of longitudinal strain, the usefulness of evaluating RV circumferential strain has been reported in patients with pectus excavatum8 and in some SLE cases7. Through-plane motion may affects 2D measures of circumferential strain using a fixed imaging plane , overloaded RV , and degenerated RV (arrhythmogenic right ventricular cardiomyopathy: ARVC). The data for consecutive subjects were collected for each etiology of RV structural abnormality. All subjects were recruited in a single center (the Cardiovascular Imaging Clinic Iidabashi) and all were recruited consecutively in each group over a specified period for that group (as noted in the following sections). Considering RV disease rarity, the target sample size was set at approximately 20.The patients’ characteristics were obtained from the medical records, and all patients provided informed consent. All experiments were performed in accordance with the Declaration of Helsinki. The study was approved by the local ethical committee of the Cardiovascular Imaging Clinic Iidabashi Medical Corporation.11 (subjects with a “Not probable” classification were excluded), and they were strongly suspected of having ARVC in the CMR assessment. In all groups, subjects with images of poor quality or inadequate four-chamber view cine CMR results were excluded from the study. Each diagnosis was made by cardiologists certified by the Japan Cardiovascular Society who had each read more than 1,000 CMR images.Subjects referred by local medical institutes suspected as having any cardiac disease, but in whom cardiac disease was ruled out on CMR, with reported RV volumetric assessment, were recruited as the Control group. Subjects with constricted RV (pericarditis) were eligible if they had present or past symptoms of right heart failure, or were suspected of having pericarditis by computed tomography, and if marked thickening of the pericardium (maximum > 3 mm) was recognized on CMR. Subjects with overloaded RV (ASD) were eligible if left-to-right shunting was recognized in the interatrial septum, and the Qp/Qs ratio was > 1.5 by the phase-contrast method. Subjects with Ebstein anomaly were excluded. Subjects with degenerated RV (ARVC) were eligible if RV enlargement, asynergy, or fatty infiltration were recognized, they met at least one major or minor criteria of the 2010 task force criteria by CMRWe enrolled 20 consecutive subjects as the Control group, in accordance with the inclusion criteria. CMR was performed from June 2018 to September 2018 for this group. There were no excluded cases owing to poor image quality. Twenty-three subjects with ASD were identified in the clinical records from June 2016 to Aug 2020. After excluding 8 subjects , we enrolled 15 subjects in the Overloaded RV group.Twenty consecutive subjects with chronic pericarditis were identified in the clinical records from June 2017 to February 2020. After excluding 3 subjects , we enrolled 17 subjects in the Constricted RV group. Adhesions of the pericardium on cine or tagged images were identified in 14 subjects. Symptoms  were seen in 14 subjects. Two subjects were suspected as having coronary artery disease, and another 3 subjects had histories of cardiac surgery . Eighteen consecutive subjects suspected of having ARVC were identified in the clinical records from August 2016 to August 2020. After excluding 3 subjects , we enrolled 15 subjects in the Degenerated RV group. Nine subjects were classified as definite, 4 subjects were classified as borderline, and 2 subjects were classified as probable in accordance with the 2010 task force criteria for ARVC. A total of 67 subjects were finally enrolled in the present study.2 and each patient’s status. Cine four-chamber view slices were obtained by referencing the left ventricular (LV) short axis and two-chamber views. After the determination of the axis between the center of the mitral valve and the apex with the two-chamber view, a four-chamber view slice that passed across the acute margin of the RV free wall was identified. Short-axis cine images were used for the RV volumetric assessment.All examinations were performed using 1.5-T MRI scanners (Philips Achieva or Canon Vantage TITAN). The scan protocol was as follows: (Phillips/Canon): steady-state free precession cine sequence, 20/24 phase/beat, slice thickness: 8 mm, repetition time: 2.7/4.2 ms, echo time: 1.4/2.1 ms, flip angle: 60°/80°, field of view: 3 8 × 38/38 × 34 cm, and matrix: 208 × 193/192 × 240. The short axis slice was obtained with a 0 mm slice gap while the four-chamber view was generally obtained as a single slice, and other views  were performed in accordance with current guidelinesA workstation  was used for post-processing of the RV volumetric data. We calculated RV end-diastolic volume (RVEDV), end-systolic volume (RVESV), stroke volume (RVSV), and ejection fraction (RVEF). Papillary muscle volume was included as part of the blood pool. Another workstation, Zio2 Cardiac Function, was used for the LV volumetric assessment. We calculated LV end-diastolic volume (LVEDV), end-systolic volume (LVESV), ejection fraction (LVEF), stroke volume (LVSV), and LV myocardial mass. Volumetric data were indexed (I) by body surface area and labeled as RVEDVI, RVESVI, RVSVI, LVEDVI, LVESVI, LVSVI, and LV-myocardial mass index.The RV shortening parameters were calculated in the cine four-chamber view retrospectively, and the parameters were defined as follows. Figure The RV diameter was defined as the maximum distance between the septum and the RV wall parallel to the annulus of the trigeminal valve. We considered FTC to represent the parameter of transverse shortening.We calculated the FTC/FLC ) ratio to assess individual RV shortening patterns.p < 0.05 was defined as statistically significant.First, we compared the fractional parameters and RV volumetric parameters among the four groups  to examine whether these parameters have the same tendency as RVEF among disease groups using Tukey’s multiple comparison procedure. Second, we compared the T/L ratio between the four groups using Tukey’s multiple comparison procedure to clarify the differences in contraction patterns between the groups. Third, we examined which parameter, FLC or FTC, showed the highest correlation using linear regression analysis for all subjects. All data were analyzed using Stata 15 (Stata Corp LLC). Continuous variables were expressed as mean ± standard deviation, and differences between the four groups were analyzed using Tukey’s test for multiple comparisons. Assuming that RV contractility comprises longitudinal and transverse shortening, the relationships between RVEF and FLC or FTC were evaluated using single and multiple linear regression analyses. Intra- and interobserver reproducibility of the measurements of FLC and FTC were assessed in 10 patients by calculating the intraclass correlation coefficients (ICC). The patients’ characteristics are shown in Table Table Regarding LV function, the Degenerative RV group had higher LVEDVI values than those in the Constricted RV group as well as higher LVESVI values than those in the Overloaded RV group. There were no significant differences between the other groups for LVEDVI and LVESVI. LVEF was lower in the Degenerative RV and Constricted RV groups compared with that in the Overloaded RV group; however, there was no significant difference compared with the Control group. The Constricted RV group had the lowest LVSVI among the four groups.Regarding RV function, the Overloaded RV and Degenerative RV groups had higher RVEDVI values than those in the Control and Constricted RV groups. The Degenerative RV group had the largest RVESVI among the four groups. The Overloaded RV and Degenerated RV groups had larger RVESVI values compared with the Control and Constricted RV groups. The Control and Overloaded RV groups had higher RVEF values compared with the Constricted RV group, while the Degenerated RV groups had the lowest RVEF among the four groups. Among the four groups, the Overloaded RV group had the largest RVSVI value, while the Constricted RV group had the lowest RVSVI value.Regarding FLC and FTC values, the Control and Overloaded RV groups had significantly higher FLC values compared with the Constricted RV and Degenerative RV groups. The Constricted RV group had lower FTC values than those in the Control and Overloaded RV groups. The Degenerated RV group had significantly lower FTC values than those in the Constricted RV group, so that Degenerated RV had the lowest FTC value among the four groups. Finally, FTC showed the same tendency as that of RVEF Table .Regarding the T/L ratio, the Degenerated RV group had the lowest ratio among the four groups, with a T/L ratio of < 1 (FTC < FLC). Figure 2: 0.211; p < 0.001), while the correlation between FTC and RVEF was strong . As shown in Table p < 0.01) was a stronger explanatory variable compared with FLC .Figure Regarding the intraobserver reproducibility, the ICC was 0.903 (95% CI 0.677–0.974) for FLC and 0.961 (95% CI 0.861–0.990) for FTC. The time required to measure these parameters was 67.1 ± 15 s for operator A. Regarding interobserver reproducibility, the ICC was 0.819 (95% CI 0.453–0.951) for FLC and 0.894 (95% CI 0.653–0.972) for FTC. The time required to measure these parameters was 168 ± 28 s for operator B. Representative cases are shown in Fig. 13. MRI can visualize the entire morphology of the RV by cine stack; therefore, there may be controversy regarding the necessity of RV fractional parameters derived using only single-slice images. However, RV functional parameters derived by two-dimensional echocardiography were reported to be poorly correlated with MRI-derived RV volume, and these correlations improved only modestly when two-dimensional measurements were performed using MRI14. High intra- and interobserver reproducibility of LV and RV volume measurements on CMR was reported in several studies. However, these measurements require more than 20–30 min per case4. Therefore, some institutes are unable to analyze RV volumetry in all cases in clinical practice. In comparison, measurements of the fractional parameters described in the present study can be obtained within 2 min by a skilled operator, as shown in our results, without additional equipment. Left ventricular stroke volume should be used to assess the validity of RV volume analysis 2, which is difficult in the presence of valvular disease or intracardiac shunts. This new parameter may be able to predict right ventricular contractility within a certain range in every situation, and correct for errors in the analysis by measuring it beforehand.Our study demonstrated that the RV parameters, FLC and FTC, can evaluate RV shortening from a new perspective. Fractional shortening parameters for RV have been studied using echocardiography, and all studies showed moderate correlation with MRI-derived RV function15. We defined “CMR-derived TAPSE” as “RVLd-RVLs”, and ran the same analysis , replacing FLC with CMR-derived TAPSE  than FLC . The target population of the present study has a large variation in RV size. In such cases, standardizing the excursion distance by the length of the entire RV may lead to a more accurate assessment of contractility. And CMR-derived TAPSE failed to show a significant correlation in a multiple regression analysis with the FTC, as well as FLC.TAPSE (tricuspid annular plane systolic excursion) is a very widely used measure of RV longitudinal contraction as a standard. There have been some reports evaluating right ventricular function using CMR-derived TAPSEPSE Fig. . In univ16. On the epicardial surface, circumferentially-oriented fibers are present, which are shared with LV epicardial myofibers. In contrast, subendocardial myofibers form longitudinal lines, and these fibers are mainly responsible for longitudinal shortening, which generates the largest part of RV contraction in healthy subjects17. However, once RV pressure overload occurs, it may lead to ventricular hypertrophy and morphological changes to reduce the wall stress. Under these circumstances, the dominance of the circumferential fibers can be observed16. A comparative study of echocardiography and CMR involving subjects with precapillary pulmonary hypertension showed that correlations between tricuspid annular plane systolic excursion or fractional longitudinal wall motion and RVEF were relatively mild when compared with correlations between functional area change and RVEF18. These findings indicate that both longitudinal contraction and transverse contraction must be considered in subjects with RV dysfunction or pulmonary hypertension.The present study also demonstrated that both longitudinal and transverse shortening play important roles in RV contraction, especially in subjects with RV-related disease. The RV myocardial structure mainly comprises two layers6, similar to the FLC value of the Control group in the present study of 23.4% ± 4.6%.As mentioned, our preliminary parameter, FTC, can determine maximum RV diameter visually in each cardiac phase on four-chamber cine CMR, and using the FTC value, we can minimize the influence of longitudinal shortening. Using this method, rating the fractional shortening parameters may pioneer disease- or individual-specific RV function analysis beyond conventional volumetry. Additionally, FLC may be approximated to RV longitudinal strain measured by feature tracking. A meta-analysis by Vo et al. showed that RV longitudinal strain varied between studies, and the mean value derived using a random effects model was − 21.8%5. We agree that the largest component of RV contraction in healthy subjects is longitudinal contraction. One of the ideas to resolve this discrepancy is that longitudinal contraction is not perpendicular to the AV valve, so the force is distributed vertically and parallel  to the annular surface. This creates transverse shortening even in normal subjects. In addition, Circumferential (or transverse) muscle tension will be essential as a supplementary factor even in healthy subjects with longitudinal-dominant contraction  is a condition in which the loss of pericardial elasticity causes restriction on diastolic filling of the heart21. Defects with shunts with Qp/Qs ratios > 1.5 are considered significant and are responsible for different degrees of right heart volume overload22. Our study demonstrated that the Overloaded RV group had preserved RVEF and the same range of contraction parameter (FLC/FTC) values as those of the Control group, and there were statistically significant differences in T/L ratios in the Overloaded RV group compared with those in the Degenerative RV group. These findings indicate that FLC, FTC, and T/L ratio can distinguish Overloaded RV and Degenerated RV, both of which present with RV enlargement.ASD is the most common congenital heart disease with left-to-right shunting in adults11. Te Riele et al. reported that “mutation-positive” ARVC describes a previously unrecognized characteristic pattern of disease involving the basal inferior and anterior RV, and the posterolateral LV, while the RV apex is involved in only advanced ARVC23. Our study, showing predominantly impairment of transverse contraction (FTC) compared with longitudinal contraction (FLC), may indicate some relationships with a specific distribution of lesions in subjects with ARVC.ARVC, which we classified as Degenerated RV, is a genetically determined heart muscle disorder that is characterized pathologically by fibro-fatty replacement of the right ventricular myocardium. The distribution of this structural abnormality is described as the “triangle of dysplasia” 24. AUC was 0.701 for FLC, 0.921 for FTC, 0.855 for T/L ratio, and 0.938 for RVEF, respectively. FTC was able to predict ARVC more accurately than FLC (p = 0.001), and T/L ratio showed comparable accuracy to RVEF (p = 0.170), considering that RVEF itself is included in the diagnostic criteria for ARVC, FTC and T/L ratio have high diagnostic power for “Degenerated RV”.After showing the characteristics of FLC, FTC, and T/L ratio in the subjects with ARVC, we additionally examined how accurately the FLC, FTC and T/L can predict "Degenerative RV" using ROC curves for the entire population of present study Fig. . EqualitOur study has some limitations. First, this was a single-center, cross-sectional study. Additionally, the rarity of each disease resulted in small sample sizes. Second, as mentioned, we could not assess echocardiography simultaneously because our institution is an outpatient imaging center. Third, RV contraction is affected by pressure overload; therefore, relationships between RV contraction patterns (T/L ratio) and RV pressure overload should be investigated further. Furthermore, we couldn’t obtain the data of strain analysis due to the lack of technical equipment. Further comparative study of strain analysis and present parameters is needed for the assessment of accuracy of the present preliminary parameters.In conclusion, transverse shortening plays an important role in RV contraction; more so than longitudinal shortening. Bi-directional RV fractional parameters are easily measured, reflect RV contraction to some extent, have the potential to differentiate the etiology of RV dysfunction and detect abnormal RV morphology.Supplementary Figure S1.Supplementary Legends.Supplementary Table S1.