Left Ventricular Endocardium Research Articles

Unipolar Voltage Mapping to Predict Recovery of Left Ventricular Ejection Fraction in Patients With Recent-Onset Nonischemic Cardiomyopathy.

The ability to predict recovery of left ventricular ejection fraction (LVEF) in response to guideline-directed therapy among patients with nonischemic cardiomyopathy is desired. We sought to determine whether left ventricular endocardial unipolar voltage measured during invasive electroanatomic mapping could be used to predict LVEF recovery among those with recent-onset nonischemic cardiomyopathy. We analyzed the left ventricular voltage maps of patients included in the eMAP trial (Electrogram-Guided Myocardial Advanced Phenotyping; NCT03293381), a prospective, nonrandomized, interventional trial conducted at 2 institutions between 2017 and 2020. Patients had recent-onset nonischemic cardiomyopathy defined by LVEF ≤45% and development of symptoms or signs of heart failure within the past 6 months. Detailed voltage maps of the left ventricular endocardium were generated using the CARTO electroanatomic mapping system. Abnormal unipolar amplitude was defined as <8.27 mV. The primary end point was recovery of LVEF (Recovery) defined by a 1-year LVEF ≥50% or ≥45% with ≥10% increase from baseline. Of the 29 enrolled patients (median age, 49 years [25th percentile, 39; 75th percentile, 59], 8 females [27.6%]), LVEF recovered in 13 (44.8%) by 1-year follow-up. The percentage of total endocardial surface area with unipolar voltage abnormality (AUA) was significantly lower among Recovery patients than No Recovery patients (18.2% [6.4, 22.4] versus 80.0% [29.5, 90.9]; P=0.004). Percent AUA was associated with lower likelihood of Recovery (odds ratio, 0.64 per 10% increase in AUA; 95% CI, 0.47-0.88; P=0.006). A 28% cutoff value for percent AUA was 92% sensitive and 75% specific with an area under the receiver operating characteristic curve of 0.81 (95% CI, 0.63-0.99; P=0.001) for predicting recovery versus no recovery. The majority of patients (12 of 13; 92.3%) with a percent AUA >28% did not recover. Left ventricular unipolar voltage abnormality is a potent predictor of LVEF recovery among patients recently diagnosed with nonischemic cardiomyopathy. Detailed left ventricular unipolar voltage mapping could therefore be used as a valuable prognostic tool in guiding treatment decisions.

Nexilin in cardiomyopathy: unveiling its diverse roles with special focus on endocardial fibroelastosis.

Cardiac disorders exhibit considerable heterogeneity, and understanding their genetic foundations is crucial for their diagnosis and treatment. Recent genetic analyses involving a growing number of participants have uncovered novel mutations within both coding and non-coding regions of DNA, contributing to the onset of cardiac conditions. The NEXN gene, encoding the Nexilin protein, an actin filament-binding protein, is integral to normal cardiac function. Mutations in this gene have been linked to cardiomyopathies, cardiovascular disorders, and sudden deaths. Heterozygous or homozygous variants of the NEXN gene are associated with the development of endocardial fibroelastosis (EFE), a rare cardiac condition characterized by excessive collagen and elastin deposition in the left ventricular endocardium predominantly affecting infants and young children. EFE occurs both primary and secondary to other conditions and often leads to unfavorable prognoses and outcomes. This review explores the role of NEXN genetic variants in cardiovascular disorders, particularly EFE, revealing that functional mutations are not clustered in a specific domain of Nexilin based on the cardiac disorder phenotype. Our review underscores the importance of understanding genetic mutations for the diagnosis and treatment of cardiac conditions.

Efficacy of mitral annular velocity as an alternative marker of left ventricular global longitudinal strain to detect the risk of cancer therapy-related cardiac disorders.

Left ventricular longitudinal function can be rapidly evaluated by measuring S' and mitral annular plane systolic excursion (MAPSE) using tissue Doppler imaging. Even when the image quality is poor and the left ventricular endocardium is not visible, S' and MAPSE can be measured if the mitral annulus is visible. However, the utility of S' and MAPSE in diagnosing cancer therapy-related cardiac dysfunction (CTRCD) remains unclear. This study aimed to examine the diagnostic performance of S' and MAPSE and determine appropriate cutoff values. We retrospectively enrolled 279 breast cancer patients who underwent pre- or postoperative chemotherapy with anthracyclines and trastuzumab from April 2020 to November 2022. We compared echocardiographic data before chemotherapy, 6 months after chemotherapy initiation, and 1 year later. CTRCD was defined as a decrease in left ventricular ejection fraction below 50%, with a decrease of ≥10% from baseline or a relative decrease in left ventricular global longitudinal strain (LVGLS) of ≥15%. A total of 256 participants were included in this study, with a mean age of 50.2±11 years. Fifty-six individuals (22%) developed CTRCD within 1 year after starting chemotherapy. The cutoff value for septal S' was 6.85cm/s (AUC=.81, p<.001; sensitivity 74%; specificity 73%), and for MAPSE was 11.7mm (AUC=.65, p=.02; sensitivity 79%; specificity 45%). None of the cases with septal S' exceeding 6.85cm/s had an LVGLS of ≤15%. Septal S' is a useful indicator for diagnosing CTRCD. Septal S' decreased at the same time or earlier than the decrease in LVGLS. The septal S' demonstrated higher diagnostic ability for CTRCD compared to LVGLS.

Cardiac resynchronization therapy using endocardial versus trans-coronary sinus, epicardial left ventricular pacing: the Epi-Endo study

Abstract Aims Some studies have suggested that cardiac resynchronization therapy (CRT) using endocardial left ventricular (LV) pacing (Endo-CRT) is superior to a conventional transvenous, epicardial CRT (Epi-CRT). To determine whether, in CRT recipients, endocardial LV pacing is haemodynamically superior to trans-coronary vein (trans-CV) LV epicardial pacing. Methods and results At implantation patients (n=16; aged 68.9±8.32 years; 13 male) underwent Epi-CRT and Endo-CRT in basal, mid and apical myocardial segments, delivered using the trans-CS lead and an intra-cavitary, roving EP catheter to achieve juxtapositions of the epicardial and endocardial side of the LV free wall respectively. Myocardial scar was quantified using cardiovascular magnetic resonance. An acute haemodynamic response (AHR) was defined as a ≥10% increase in the maximal rate of rise of LV pressure (%LV dP/dtmax) in relation to RV pacing (DOO). When the 84 paired segments were taken together, the %ΔLV dP/dtmax was higher with Endo-CRT than with Epi-CRT (9.9±8,6% vs 7.9±8.3% respectively, p&amp;lt;0.002; 52.3% vs 28.6% responders [p&amp;lt;0.045). However, Endo-CRT was not always superior to epi-CRT in individual patients. For example, in basal segments, only 5/10 (50%) patients were converted from non-responders with epi-CRT to responders with endo-CRT whereas 1/4 (25%) epi-CRT responder was converted to a non-responder with endo-CRT (Figure). There was no difference in ΔLV dP/dtmax between Epi-CRT and endo-CRT in segments with myocardial scar. Conclusions On average, endo-CRT provides a better AHR than epi-CRT. Within patients, however, endo-CRT is not always better.Epicardial versus Endocardial CRT

Assessment of deep learning segmentation for real-time free-breathing cardiac magnetic resonance imaging at rest and under exercise stress

In recent years, a variety of deep learning networks for cardiac MRI (CMR) segmentation have been developed and analyzed. However, nearly all of them are focused on cine CMR under breathold. In this work, accuracy of deep learning methods is assessed for volumetric analysis (via segmentation) of the left ventricle in real-time free-breathing CMR at rest and under exercise stress. Data from healthy volunteers (n = 15) for cine and real-time free-breathing CMR at rest and under exercise stress were analyzed retrospectively. Exercise stress was performed using an ergometer in the supine position. Segmentations of two deep learning methods, a commercially available technique (comDL) and an openly available network (nnU-Net), were compared to a reference model created via the manual correction of segmentations obtained with comDL. Segmentations of left ventricular endocardium (LV), left ventricular myocardium (MYO), and right ventricle (RV) are compared for both end-systolic and end-diastolic phases and analyzed with Dice’s coefficient. The volumetric analysis includes the cardiac function parameters LV end-diastolic volume (EDV), LV end-systolic volume (ESV), and LV ejection fraction (EF), evaluated with respect to both absolute and relative differences. For cine CMR, nnU-Net and comDL achieve Dice’s coefficients above 0.95 for LV and 0.9 for MYO, and RV. For real-time CMR, the accuracy of nnU-Net exceeds that of comDL overall. For real-time CMR at rest, nnU-Net achieves Dice’s coefficients of 0.94 for LV, 0.89 for MYO, and 0.90 for RV and the mean absolute differences between nnU-Net and the reference are 2.9 mL for EDV, 3.5 mL for ESV, and 2.6% for EF. For real-time CMR under exercise stress, nnU-Net achieves Dice’s coefficients of 0.92 for LV, 0.85 for MYO, and 0.83 for RV and the mean absolute differences between nnU-Net and reference are 11.4 mL for EDV, 2.9 mL for ESV, and 3.6% for EF. Deep learning methods designed or trained for cine CMR segmentation can perform well on real-time CMR. For real-time free-breathing CMR at rest, the performance of deep learning methods is comparable to inter-observer variability in cine CMR and is usable for fully automatic segmentation. For real-time CMR under exercise stress, the performance of nnU-Net could promise a higher degree of automation in the future.

Anatomically Based Ablation of Left Ventricular Summit Premature Ventricular Complexes Guided by Intracardiac Echocardiography.

Catheter ablation of premature ventricular contractions (PVCs) arising from the left ventricular summit (LVS) presents technical challenges due to the regional anatomy and frequent intramural site of origin (SOO). Intracardiac echocardiography (ICE) and the CARTOSOUND® (Biosense Webster, Diamond Bar, CA, USA) module allow the operator to directly reconstruct and visualize the dimensions and orientation of the LVS live and present it in relation to neighboring structures. We retrospectively reviewed consecutive cases between January 2021 and December 2022 of patients undergoing PVC ablation for a presumed LVS origin. The LVS was reconstructed by creating a three-dimensional representation of the left ventricular septum, using two-dimensional ICE sections. The earliest site in each chamber was tagged on the reconstructed LVS, and the presumed SOO was localized using a geometrical center point from all sites. Ablation was first delivered to the earliest site, except when the presence of coronary branches precluded radiofrequency delivery within the great cardiac vein. Of 20 patients (8 women, 62.4 ± 7.1 years old) with a presumed LVS origin, 12 had PVC recurrence within the monitoring period after the initial ablation for 192.5 ± 37.2 s at the earliest site. Among them, earliest activation was seen at the sinus of Valsalva (SoV), coronary venous system (CVS), and left ventricular endocardium (LVE) in four, six, and two patients, respectively. Using the reconstructed LVS, the anatomically closest site to the SOO was identified in the SoV, CVS, and LVE in four, two, and six cases, respectively. Throughout the study period (14.5 months; range, 9.3-19.7 months), 17 patients (85%) had complete elimination of PVCs as evaluated by 24-h event monitors at the 12-month visit. In 50% of cases, among patients in whom ablation at the earliest signal was unsuccessful, the site of successful ablation did not correlate with the second earliest signal or had no identifiable signal during initial activation mapping. The reconstructed LVS not only guided activation mapping but also identified sites proximal to the center point that had either a late activation signal, a low-amplitude signal, or no signal at all.

Assessment of left ventricular ejection fraction in artificial intelligence based on left ventricular opacification.

Left ventricular opacification (LVO) improves the accuracy of left ventricular ejection fraction (LVEF) by enhancing the visualization of the endocardium. Manual delineation of the endocardium by sonographers has observer variability. Artificial intelligence (AI) has the potential to improve the reproducibility of LVO to assess LVEF. The aim was to develop an AI model and evaluate the feasibility and reproducibility of LVO in the assessment of LVEF. This retrospective study included 1305 echocardiography of 797 patients who had LVO at the Department of Ultrasound Medicine, Union Hospital, Huazhong University of Science and Technology from 2013 to 2021. The AI model was developed by 5-fold cross validation. The validation datasets included 50 patients prospectively collected in our center and 42 patients retrospectively collected in the external institution. To evaluate the differences between LV function determined by AI and sonographers, the median absolute error (MAE), spearman correlation coefficient, and intraclass correlation coefficient (ICC) were calculated. In LVO, the MAE of LVEF between AI and manual measurements was 2.6% in the development cohort, 2.5% in the internal validation cohort, and 2.7% in the external validation cohort. Compared with two-dimensional echocardiography (2DE), the left ventricular (LV) volumes and LVEF of LVO measured by AI correlated significantly with manual measurements. AI model provided excellent reliability for the LV parameters of LVO (ICC > 0.95). AI-assisted LVO enables more accurate identification of the LV endocardium and reduces observer variability, providing a more reliable way for assessing LV function.

Chemical ablation of the left ventricular endocardium reduces ventricular fibrillation inducibility in acute ischemic canine heart.

Ventricular fibrillation remains as the major cause of death in patients with acute myocardial infarction. Effects of trans-atrial chemical ablation of the left ventricular (LV) endocardium with Lugol's solution on ventricular fibrillation inducibility and ventricular conduction were examined in canines with acute myocardial ischemia. Chemical ablation of the LV endocardium with Lugol's solution or normal saline was preformed through a left atrial appendage in 14 canines 30 min after occlusion of the left anterior coronary artery. Ventricular fibrillation threshold decreased after the coronary artery occlusion and increased after endocardial chemical ablation. There was a significant difference in the ventricular fibrillation threshold after chemical ablation between with Lugol's solution and with normal saline (25.9 ± 9.2 mA vs. 11.3 ± 2.7 mA, p < .01). QRS width significantly increased from 88 ± to 116 ± (p < .01) after the chemical ablation with Lugol's solution, and the activation map of the ventricles demonstrated a left bundle branch block ventricular conduction pattern. Histological examination of the LV endocardium showed lymphocyte infiltration for a depth of 1 mm. Chemical ablation of the LV endocardium with Lugol's solution injures endocardial conduction system and increases ventricular fibrillation threshold in the early phase of myocardial ischemia in canines. The procedure may be useful in suppressing intractable ventricular tachyarrhythmias in patients with acute myocardial ischemia.

Ventricular Tachycardia Ablation in Patients With Desmoplakin Cardiomyopathy

BackgroundDesmoplakin (DSP) pathogenic variants are rare causes of arrhythmogenic cardiomyopathy and often involve the right and left ventricles. Ventricular tachycardia (VT) ablations may be required in these patients, but procedural characteristics have not been reported. ObjectivesIn this study, the authors sought to report a multicenter experience of VT ablation in patients with DSP pathogenic variants. MethodsVT ablations performed in patients with known DSP pathogenic variants were analyzed across 6 centers in 3 countries. Patient characteristics and acute and long-term procedural outcomes were reported. ResultsA total of 20 patients (13 men, median age 43 years [Q1-Q3: 41.5-53.0 years], left ventricular ejection fraction 43.0% [Q1-Q3: 41.5%-53.0%], 11 previous failed ablations) were referred for VT ablation procedures. All patients had symptomatic VTs, with ICD therapy in 19 patients. Epicardial procedures were performed in 16 of the 20 patients. VT target sites were located in the right ventricular (RV) endocardium (n = 11), the RV epicardium (n = 4), the left ventricular (LV) endocardium (n = 2) and the LV epicardium (n = 7). In 3 patients, the VT target sites were in close proximity to coronary arteries, limiting ablation. During follow-up, VTs recurred in 11 patients, and repeated ablations were performed in 9 patients. Allowing for multiple procedures, 19 of the 20 patients remained free of VT recurrence after a median follow-up of 18 months [Q1-Q3: 5-60 months]. ConclusionsPatients with DSP cardiomyopathy often have biventricular involvement, and ablation procedures often require ablation in both ventricles and the epicardium. Recurrences are not uncommon, and the pathologic substrate can be located in close proximity to epicardial coronary arteries, limiting the success rate of ablations.

Automatic segmentation of 2D echocardiography ultrasound images by means of generative adversarial network.

Automated cardiac segmentation from two-dimensional (2D) echocardiographic images is a crucial step toward improving clinical diagnosis. Anatomical heterogeneity and inherent noise, however, present technical challenges and lower segmentation accuracy. The objective of this study is to propose a method for the automatic segmentation of the ventricular endocardium, the myocardium, and the left atrium, in order to accurately determine clinical indices. Specifically, we suggest using the recently introduced pixel-to-pixel Generative Adversarial Network (Pix2Pix GAN) model for accurate segmentation. To accomplish this, we integrate the backbone PatchGAN model for the discriminator and the UNET for the generator, for building the Pix2Pix GAN. The resulting model produces precisely segmented images, thanks to UNET's capability for precise segmentation and PatchGAN's capability for fine-grained discrimination. For the experimental validation, we use the Cardiac Acquisitions for Multi-structure Ultrasound Segmentation (CAMUS) dataset, which consists of echocardiographic images from 500 patients in 2-chamber (2CH) and 4-chamber (4CH) views at the end-diastolic (ED) and end-systolic (ES) phases. Similarly to state-of-the-art studies on the same dataset, we followed the same train-test splits. Our results demonstrate that the proposed GAN-based technique improves segmentation performance for clinical and geometrical parameters compared to the state-of-the-art methods. More precisely, throughout the ED and ES phases, the mean Dice values for the left ventricular endocardium reached 0.961 and 0.930 for 2CH, and 0.959 and 0.950 for 4CH, respectively. Furthermore, the average ejection fraction correlation and Mean Absolute Error obtained were 0.95 and 3.2ml for 2CH, and 0.98 and 2.1ml for 4CH, outperforming the state-of-the-art results.

Visualization of Left Ventricular Endocardium Activation Time during Cardiac Conduction System Pacing

Introduction. Right ventricular myocardial pacing leads to asynchronous contraction of the left ventricle (LV) and can impair its contractility over time. Stimulation of the conduction system of the heart ensures physiological activation of the ventricles.&#x0D; The aim. To visualize the pattern of propagation of the electrical front on the activation map of the LV endocardium during conduction system pacing and during right ventricular myocardial pacing.&#x0D; Materials and methods. In two patients with the conduction system pacing, who were operated at the National Amosov Institute of Cardiovascular Surgery, invasive LV activation mapping was performed on various options of cardiac pacing using the EnSite Precision TM navigation system. One patient with complete atrioventricular block had nonselective His bundle pacing. The second patient had dilated cardiomyopathy and indications for cardiac resynchronization therapy and ablation of the atrioventricular junction due to chronic tachyform of atrial fibrillation. After an unsuccessful attempt to place LV lead in coronary sinus, a lead for left bundle branch pacing was implanted. Different activation maps of the LV endocardium were built in two patients with two types of cardiac pacing: right ventricular myocardial pacing and cardiac conduction system pacing.&#x0D; Results. The total LV endocardial activation time was significantly different in the two studied patients with different pacing options. In a patient with non-selective stimulation of His bundle, the total LV endocardial activation time was 43 ms (QRS width 126 ms, the interval from the stimulus to the peak of the R wave in lead V6 78 ms). After switching to right ventricular myocardial pacing with a decrease in the pacing amplitude, the total LV endocardial activation time prolonged to 90 ms (QRS width 165 ms, the interval from the stimulus to the peak of the R wave in lead V6 117 ms). In a patient with left bundle branch pacing, total LV endocardial activation time was 51 ms (QRS width 160 ms, the interval from the stimulus to the peak of the R wave in lead V6 66 ms). With switching exclusively to right ventricular pacing the total LV endocardial activation time prolonged to 93 ms (stimulated QRS width 180 ms). At the same time, the activation pattern of the LV endocardium was significantly different, since the right ventricular lead was located closer to the apex.&#x0D; Conclusions. Conduction system pacing provides rapid physiological LV activation and potentially avoids the negative consequences of asynchronous slow ventricular activation during right ventricular pacing.

Transcoronary mapping with an over-the-wire multielectrode catheter in scar-related ventricular tachycardia patients.

The usefulness of coronary venous system mapping has been reported for assessing intramural and epicardial substrates in patients with scar-related ventricular tachycardia (VT). However, there has been little data on mapping from coronary arteries. We investigated the safety and utility of mapping from coronary arteries with a novel over-the-wire multielectrode catheter in scar-related VT patients. Ten consecutive scar-related VT patients with non-ischaemic cardiomyopathy who underwent mapping from a coronary artery were analysed. Six patients underwent simultaneous coronary venous mapping. High-density maps were created by combining the left ventricular endocardium and coronary vessels. Substrate maps were created during the baseline rhythm with 2438 points (IQR 2136-3490 points), including 329 (IQR 59-508 points) in coronary arteries. Abnormal bipolar electrograms were successfully recorded within coronary arteries close to the endocardial substrate in seven patients. During VT, isthmus components were recorded within the coronary vessels in three patients with no discernible isthmus components on endocardial mapping. The ablation terminated the VT from an endocardial site opposite the earliest site in the coronary arteries in five patients. The transcoronary mapping with an over-the-wire multielectrode catheter can safely record abnormal bipolar electrograms within coronary arteries. Additional mapping data from the coronary vessels have the potential to assess three-dimensional ventricular substrates and circuit structures in scar-related VT patients.

Experience of left ventricular outflow tract arrhythmia ablation in paediatric patients using limited fluoroscopy and three-dimensional mapping technique.

The left ventricular outflow tract is an important source of ventricular arrhythmias. Up to one-third of all idiopathic ventricular arrhythmias in patients with structurally normal hearts may arise from this region. We would like to share the results of our left ventricular outflow tract ablation using three-dimensional mapping and limited fluoroscopy. This is a single-centre retrospective cohort study. Forty-six consecutive patients who underwent left ventricular outflow tract ablation procedures between January 2015 and June 2023 were included in the study. The EnSite Precision System (Abbott, St. Paul, MN, USA) was used to facilitate mapping and to reduce or eliminate the need for fluoroscopy. The study group comprised 29 males and 17 females, with a mean age of 13.4 ± 4.5 years. The most common location for arrhythmias was the left coronary cusp (n : 21). Other locations, in sequence, included the junction of the right and left coronary commissure (n : 10), right coronary cusp (n : 10), left ventricular outflow tract endocardium (n:4), aorto-mitral junction (n : 1), and great cardiac vein (n : 1). Nine of these patients had previously undergone unsuccessful right ventricular outflow tract ablation at another centre. Cryoablation was performed in three patients, irrigated radiofrequency ablation in three patients, and conventional radiofrequency ablation in the remaining patients. The acute success rate was 100%, and no recurrences were observed. The mean follow-up period was 49.6 ± 24.4 months. All patients were asymptomatic and were being followed without antiarrhythmic medication. Although left ventricular outflow tract ablations pose a risk for coronary artery and heart valve complications, they can be performed successfully and safely with the guidance of three-dimensional mapping.

Capturing the Influence of Conduction Velocity on Epicardial Activation Patterns Using Uncertainty Quantification.

Individual variability in parameter settings, due to either user selection or disease states, can impact accuracy when simulating the electrical behavior of the heart. Here, we aim to test the impact of inevitable uncertainty in conduction velocities (CVs) on the output of simulations of cardiac propagation, given three stimulus locations on the left ventricular (LV) free wall. To understand the role of physiological variability in CV in simulations of cardiac activation, we generated detailed maps of the variability in propagation simulations by implementing bi-ventricular activation simulations and quantified the effects by deploying robust uncertainty quantification techniques based on polynomial chaos expansion (PCE). PCE allows efficient stochastic exploration with reduced computational demand by utilizing an emulator for the underlying forward model. Our results suggest that CV within healthy physiological ranges plays a small role in the activation times across all stimulation locations. However, we noticed differences in variation coefficients depending on the stimulation site, i.e., LV endocardium, midmyocardium, and epicardium. We observed low levels of variation in activation times near the earliest activation sites, whereas there was higher variation toward the termination sites. These results suggest that CV variability can play a role when simulating healthy and diseased states.

Animal study on left bundle branch current of injury and anatomic location of leads in His-purkinje conduction system pacing

Objective: Explore the relationship between tip of the left bundle branch pacing lead and anatomic location of left bundle branch as well as the mechanism of left bundle branch current of injury. To clarify the clinical value of left bundle branch current of injury during operation. Methods: The pacing leads were implanted in the hearts of two living swines. Intraoperative electrophysiological study confirmed that the left bundle branch or only the deep left ventricular septum was captured at low output. Immediately after operation, the gross specimen of swine hearts was stained with iodine to observe the gross distribution of His-purkinje conduction system on the left ventricular endocardium and its relationship with the leads. Subsequently, the swine hearts were fixed with formalin solution, and the pacing leads were removed after the positions were marked. The swine hearts were then sectioned and stained with Masson and Goldner trichrome, and the relationship between the anatomic location of the conduction system and the tip of the lead was observed under a light microscope. Results: After iodine staining of the specimen, the His-purkinje conduction system was observed with the naked eye in a net-like distribution, and the lead tip was screwed deeply and fixed in the left bundle branch area of the left ventricular subendocardium in the ventricular septum. Masson and Goldner trichrome staining showed that left bundle branch pacing lead directly passed through the left bundle branch when there was left bundle branch potential with left bundle branch current of injury, while it was not directly contact the left bundle branch when there was left bundle branch potential without left bundle branch current of injury. Conclusion: The left bundle branch current of injury observed on intracardiac electrocardiogram during His-purkinje conduction system pacing suggests that the pacing lead directly contacted the conduction bundle or its branches, therefore, the captured threshold was relatively low. Left bundle branch current of injury can be used as an important anatomic and electrophysiological evidence of left bundle branch capture.

Cardiac Resynchronisation with Conduction System Pacing.

To date, biventricular pacing (BiVP) has been the standard pacing modality for cardiac resynchronisation therapy. However, it is non-physiological, with the activation spreading between the left ventricular epicardium and right ventricular endocardium. Up to one-third of patients with heart failure who are eligible for cardiac resynchronisation therapy do not derive benefit from BiVP. Conduction system pacing (CSP), which includes His bundle pacing and left bundle branch area pacing, has emerged as an alternative to BiVP for cardiac resynchronisation. There is mounting evidence supporting the benefits of CSP in achieving synchronous ventricular activation and repolarisation. The aim of this review is to summarise the current options and outcomes of CSP when used for cardiac resynchronisation in patients with heart failure.

Super-efficient Echocardiography Video Segmentation via Proxy- and Kernel-Based Semi-supervised Learning

Automatic segmentation of left ventricular endocardium in echocardiography videos is critical for assessing various cardiac functions and improving the diagnosis of cardiac diseases. It is yet a challenging task due to heavy speckle noise, significant shape variability of cardiac structure, and limited labeled data. Particularly, the real-time demand in clinical practice makes this task even harder. In this paper, we propose a novel proxy- and kernel-based semi-supervised segmentation network (PKEcho-Net) to comprehensively address these challenges. We first propose a multi-scale region proxy (MRP) mechanism to model the region-wise contexts, in which a learnable region proxy with an arbitrary shape is developed in each layer of the encoder, allowing the network to identify homogeneous semantics and hence alleviate the influence of speckle noise on segmentation. To sufficiently and efficiently exploit temporal consistency, different from traditional methods which only utilize the temporal contexts of two neighboring frames via feature warping or self-attention mechanism, we formulate the semi-supervised segmentation with a group of learnable kernels, which can naturally and uniformly encode the appearances of left ventricular endocardium, as well as extracting the inter-frame contexts across the whole video to resist the fast shape variability of cardiac structures. Extensive experiments have been conducted on two famous public echocardiography video datasets, EchoNet-Dynamic and CAMUS. Our model achieves the best performance-efficiency trade-off when compared with other state-of-the-art approaches, attaining comparative accuracy with a much faster speed. The code is available at https://github.com/JingyinLin/PKEcho-Net.

Comparative study of myocardial function in cases of feline hypertrophic cardiomyopathy with and without dynamic left-ventricular outflow-tract obstruction.

In recent years, hypertrophic cardiomyopathy (HCM) in cats has become much more common in clinical practice due to improvements in diagnostic techniques and equipment performance. One phenotype is obstructive HCM with left ventricular (LV) outflow tract obstruction (DLVOTO). It has been reported that the presence or absence of DLVOTO does not affect long-term prognosis in cats with HCM. In this study, we evaluated and compared myocardial function in HCM-affected cats with and without DLVOTO using the two-dimensional speckle-tracking echocardiography. LV longitudinal strain of the endocardial, epicardial, and whole layer and LV circumferential strain of the epicardium were significantly decreased in all HCM-affected cats compared to healthy cats. However, these values were not significantly different between those with and without DLVOTO. In contrast, the endocardial and whole layers of LV circumferential strain were only significantly decreased in HCM-affected cats with DLVOTO compared to healthy cats. This could be attributed to the fact that the LV pressure load associated with DLVOTO affected the endocardial myocardium more in the LV endocardial layer, and that lower values of LV endocardial strain lowered the values of LV strain in the whole layer. In conclusion, our results suggest that LV myocardial function may have been more compromised in the HCM-affected cats with DLVOTO.

Automated Detection of Apical Foreshortening in Echocardiography Using Statistical Shape Modelling

Automated detection of foreshortening, a common challenge in routine 2-D echocardiography, has the potential to improve quality of acquisitions and reduce the variability of left ventricular measurements. Acquiring and labelling the required training data is challenging due to the time-intensive and highly subjective nature of foreshortened apical views. We aimed to develop an automatic pipeline for the detection of foreshortening. To this end, we propose a method to generate synthetic apical-four-chamber (A4C) views with matching ground truth foreshortening labels. A statistical shape model of the four chambers of the heart was used to synthesise idealised A4C views with varying degrees of foreshortening. Contours of the left ventricular endocardium were segmented in the images, and a partial least squares (PLS) model was trained to learn the morphological traits of foreshortening. The predictive capability of the learned synthetic features was evaluated on an independent set of manually labelled and automatically curated real echocardiographic A4C images. Acceptable classification accuracy for identification of foreshortened views in the testing set was achieved using logistic regression based on 11 PLS shape modes, with a sensitivity, specificity and area under the receiver operating characteristic curve of 0.84, 0.82 and 0.84, respectively. Both synthetic and real cohorts showed interpretable traits of foreshortening within the first two PLS shape modes, reflected as a shortening in the long-axis length and apical rounding. A contour shape model trained only on synthesized A4C views allowed accurate prediction of foreshortening in real echocardiographic images.

Kinetic energy as a factor in assessing the work of the heart in patients with aortic stenosis

Goal. To analyze the evolution of the myocardial contraction force through the assessment of kinetic energy in patients with aortic stenosis based on intraventricular blood flowsMaterial and methods. According to the selection criteria, 21 healthy volunteers (age 34 ± 3) and 105 patients with aortic stenosis (age 62 ± 4) were examined before and after surgery for 7–10 days. Transthoracic echocardiography was performed on a Vivid E9 device in 2, 3 and 4 chamber positions with registration of intraventricular blood flows, calculation of the rate of change in volume and kinetic energy depending on the left ventricular EDV, pressure gradient (ΔP) on the aortic valve with an assessment of the displacement of the left ventricular endocardium contour, based on technologies for tracking speckles of ultrasonic images in the MultiVox program.Results. Our goal was to quantify kinetic energy (KE) during the entire cardiac cycle of the left ventricle (LV) using echocardiography. One of the main strengths identified in these studies is the high reproducibility of the assessment of LV blood flow and hemodynamics the average coefficient of variability 7 ± 2% for assessing LV function. Studies have shown increased diagnostic reliability without spending additional time. In systole, the KE before the LV operation was higher than normal values (0.62–0.78 J) after the operation, the KE approached the norm, averaging 0.55 J.Conclusion. Changes in intraventricular blood flow in patients with pressure overload of the heart demonstrate higher systolic energy compared to the control group. Different time values of energy in systole and diastole, observed in patients before surgery, represent an objective approach to assessing the work of the heart. The energy analysis reflects earlier signs of mechanical myocardial disorders, compared with the ejection fraction and, possibly, predict the development of cardiac remodeling. Adequate correction of the defect normalizes the work of the heart already in the early postoperative period.