The right ventricle in congenital heart disease

Early Outcomes of Right Ventricular Pressure and Volume Overload in an Ovine Model

Right ventricular (RV) failure is a common complication in multiple congenital heart disease (CHD), significantly increasing morbidity and mortality. Despite its impact, no therapies specifically target the failing RV. The growing population of CHD patients underscores the need to understand the pathophysiology of RV failure through preclinical research. This study aimed to develop an ovine model of RV failure induced by pressure and volume overload. A total of 14 juvenile sheep randomly underwent pulmonary artery banding (n = 6), pulmonary leaflet perforation (n = 4), and pulmonary annulotomy with transannular patching (TAP) (n = 4). Detailed anesthetic and surgical protocols were described, and intraoperative and early postoperative complications were evaluated. Acute RV pressure overload resulted in a 120% increase in RV pressure (p = 0.0312). The stroke volume index and cardiac index significantly declined (p = 0.0312), and there was a significant decrease in ScvO2 (p = 0.0312). Both TAP and leaflet perforation achieved moderate-to-severe pulmonary regurgitation. Both procedures led to an incremental trend in RV pressures and resulted in a 24% increase in the stroke volume index. All techniques demonstrated safety and feasibility, with low mortality. This comprehensive model could be reproducible in other large animal models, offering a robust platform for preclinical research into CHD-RV failure models.

Right ventricular electrophysiology and arrhythmias in adults with congenital heart disease: scientific basis for management

Right ventricular (RV) dysfunction and arrhythmias are major concerns in adults with congenital heart disease (CHD). The relationship between RV dysfunction and arrhythmogenesis is bidirectional, with structural and electrical remodeling contributing to arrhythmia development and, conversely, arrhythmias exacerbating RV failure. In addition to an RV in the standard subpulmonary position failing as a result of pressure and/or volume overload, other phenotypes associated with RV dysfunction in CHD include transposition of the great arteries with a systemic (subaortic) RV and univentricular hearts with a predominant RV morphology. The RV is better suited for low-pressure workloads. When it supports the systemic circulation, it undergoes remodeling changes that promote arrhythmias, which can provoke a cycle of worsening dysfunction and arrhythmogenesis. Arrhythmias can worsen RV dysfunction by impairing hemodynamic stability, reducing cardiac output, provoking dyssynchrony, and inducing tachycardia-induced cardiomyopathy. Cellular mechanisms, including myocardial fibrosis, dysregulation of ion channels, and abnormal gap junction function, are central to this process, facilitating both reentrant and triggered arrhythmias. Conduction disturbances, whether inherent or caused by fibrosis or pacing, compound these effects, aggravating both RV dysfunction and arrhythmia perpetuation. Management strategies must be comprehensive and include pre-emptive approaches to minimize arrhythmias, alongside early detection. Individualized therapies may include catheter ablation and cardiac implantable electronic devices, with treatment tailored to the specific RV phenotype and arrhythmia type. This review emphasizes the importance of personalized interventions to prevent the vicious cycle of RV dysfunction and arrhythmias in CHD. Further research is essential to optimize therapeutic strategies and address care-limiting knowledge gaps.

Characterization of Intracardiac Flow in the Right Ventricle With Pressure and Volume Overload in Children

Background

Blood flow visualization using vector flow mapping (VFM) holds potential as a novel indicator of right ventricular (RV) function.

Methods

This study included 12 patients with atrial septal defect (ASD group, mean (± standard deviation) age: 6.2 ± 1.5 years), six patients with pulmonary hypertension (PH group, mean age: 6.8 ± 2.3 years), and 35 healthy, age-matched children (control group, mean age: 7.3 ± 1.6 years). VFM data were obtained from the parasternal RV short-axis view.

Results

VFM images in the majority of the control group showed a counterclockwise rotating vortex below the tricuspid anterior leaflet and clockwise vortex below the septal leaflet in early diastole. In late diastole, a clockwise vortex flow appeared at the RV apex to the outflow tract. In the ASD and PH groups, the formation of vortical flow below the tricuspid valve was decreased. Late-diastolic vortices also differed from the control group, with counterclockwise or no vortex flow seen in this phase in these groups. Flow energy loss (EL), kinetic energy (KE) and energetic performance index (EPI) were related to RV systolic and diastolic functions. Mean EL over one cardiac cycle (ELcycle) was significantly higher in the PH group than in the control group (P = 0.0471). KE of the RV inflow tract (KE-RVin) and outflow tract (KE-RVout) were significantly lower in the PH group than in the control and ASD groups (P < 0.05 each).

Conclusions

These results suggest that RV vortex formation may be a factor in efficient ejection. EL, KE, and EPI may be applicable to evaluate RV contractility and diastolic function.

Impact of Right Ventricular Pressure Overload on Myocardial Stiffness Assessed by Natural Wave Imaging

BACKGROUND

Right ventricular (RV) hemodynamic performance determines the prognosis of patients with RV pressure overload. Using ultrafast ultrasound, natural wave velocity (NWV) induced by cardiac valve closure was proposed as a new surrogate to quantify myocardial stiffness.

OBJECTIVES

This study aimed to assess RV NWV in rodent models and children with RV pressure overload vs control subjects and to correlate NWV with RV hemodynamic parameters.

METHODS

Six-week-old rats were randomized to pulmonary artery banding (n = 6), Sugen hypoxia-induced pulmonary arterial hypertension (n = 7), or sham (n = 6) groups. They underwent natural wave imaging, echocardiography, and hemodynamic assessment at baseline and 6 weeks postoperatively. The authors analyzed NWV after tricuspid and after pulmonary valve closure (TVC and PVC, respectively). Conductance catheters were used to generate pressure-volume loops. In parallel, the authors prospectively recruited 14 children (7 RV pressure overload; 7 age-matched control subjects) and compared RV NWV with echocardiographic and invasive hemodynamic parameters.

RESULTS

NWV significantly increased in RV pressure overload rat models (4.99 ± 0.27 m/s after TVC and 5.03 ± 0.32 m/s after PVC in pulmonary artery banding at 6 weeks; 4.89 ± 0.26 m/s after TVC and 4.84 ± 0.30 m/s after PVC in Sugen hypoxia at 6 weeks) compared with control subjects (2.83 ± 0.15 m/s after TVC and 2.72 ± 0.34 m/s after PVC). NWV after TVC correlated with both systolic and diastolic parameters including RV dP/dtmax (r = 0.75; P < 0.005) and RV Ees (r = 0.81; P < 0.005). NWV after PVC correlated with both diastolic and systolic parameters and notably with RV end-diastolic pressure (r = 0.65; P < 0.01). In children, NWV after both right valves closure in RV pressure overload were higher than in healthy volunteers (P < 0.01). NWV after PVC correlated with RV E/E' (r = 0.81; P = 0.008) and with RV chamber stiffness (r = 0.97; P = 0.03).

CONCLUSIONS

Both RV early-systolic and early-diastolic myocardial stiffness show significant increase in response to pressure overload. Based on physiology and our observations, early-systolic myocardial stiffness may reflect contractility, whereas early-diastolic myocardial stiffness might be indicative of diastolic function.

Sparing of the Heart Facilitates Recovery From Cardiopulmonary Side Effects After Thoracic Irradiation

PURPOSE

When irradiating thoracic tumors, dose to the heart or lung has been associated with survival. We previously showed in a rat model that in addition to known side effects such as pericarditis, pneumonitis and fibrosis, heart and/or lung irradiation also impaired diastolic function and increased pulmonary artery pressure. Simultaneous irradiation of both organs strongly intensified these effects. However, the long-term consequences of these interactions are not yet known. Therefore, here, we investigated the long-term effects of combined heart and lung irradiation.

METHODS AND MATERIALS

Different regions of the rat thorax containing the heart and/or 50% of the lungs were irradiated with protons. Respiratory rate (RR) was measured biweekly as an overall parameter for cardiopulmonary function. Echocardiography of the heart was performed at 8, 26, and 42 weeks after irradiation. Tissue remodeling and vascular changes were assessed using Masson trichrome and Verhoeff-stained lung and left ventricle tissue collected at 8 and 42 weeks after irradiation.

RESULTS

During the entire experimental period RR was consistently increased after combined heart/lung irradiation. This coincided with persistent effects on lung vasculature and reduced right-ventricle (RV) contraction. In contrast, recovery of RR, pulmonary remodeling and RV contraction was observed after sparing of the heart. These corresponding temporal patterns suggest that the reduction of RV function is related to vascular remodeling in the lung.

CONCLUSIONS

Combined irradiation of lung and heart leads to an intensified, persistent reduction of cardiopulmonary function. Recovery of the pulmonary vasculature and RV function requires heart sparing.

SDF4CHD: Generative modeling of cardiac anatomies with congenital heart defects

Congenital heart disease (CHD) encompasses a spectrum of cardiovascular structural abnormalities, often requiring customized treatment plans for individual patients. Computational modeling and analysis of these unique cardiac anatomies can improve diagnosis and treatment planning and may ultimately lead to improved outcomes. Deep learning (DL) methods have demonstrated the potential to enable efficient treatment planning by automating cardiac segmentation and mesh construction for patients with normal cardiac anatomies. However, CHDs are often rare, making it challenging to acquire sufficiently large patient cohorts for training such DL models. Generative modeling of cardiac anatomies has the potential to fill this gap via the generation of virtual cohorts; however, prior approaches were largely designed for normal anatomies and cannot readily capture the significant topological variations seen in CHD patients. Therefore, we propose a type- and shape-disentangled generative approach suitable to capture the wide spectrum of cardiac anatomies observed in different CHD types and synthesize differently shaped cardiac anatomies that preserve the unique topology for specific CHD types. Our DL approach represents generic whole heart anatomies with CHD type-specific abnormalities implicitly using signed distance fields (SDF) based on CHD type diagnosis. To capture the shape-specific variations, we then learn invertible deformations to morph the learned CHD type-specific anatomies and reconstruct patient-specific shapes. After training with a dataset containing the cardiac anatomies of 67 patients spanning 6 CHD types and 14 combinations of CHD types, our method successfully captures divergent anatomical variations across different types and the meaningful intermediate CHD states across the spectrum of related CHD diagnoses. Additionally, our method demonstrates superior performance in CHD anatomy generation in terms of CHD-type correctness and shape plausibility. It also exhibits comparable generalization performance when reconstructing unseen cardiac anatomies. Moreover, our approach shows potential in augmenting image-segmentation pairs for rarer CHD types to significantly enhance cardiac segmentation accuracy for CHDs. Furthermore, it enables the generation of CHD cardiac meshes for computational simulation, facilitating a systematic examination of the impact of CHDs on cardiac functions.

Evaluation and Management of Chronic Heart Failure in Children and Adolescents With Congenital Heart Disease: A Scientific Statement From the American Heart Association

With continued medical and surgical advancements, most children and adolescents with congenital heart disease are expected to survive to adulthood. Chronic heart failure is increasingly being recognized as a major contributor to ongoing morbidity and mortality in this population as it ages, and treatment strategies to prevent and treat heart failure in the pediatric population are needed. In addition to primary myocardial dysfunction, anatomical and pathophysiological abnormalities specific to various congenital heart disease lesions contribute to the development of heart failure and affect potential strategies commonly used to treat adult patients with heart failure. This scientific statement highlights the significant knowledge gaps in understanding the epidemiology, pathophysiology, staging, and outcomes of chronic heart failure in children and adolescents with congenital heart disease not amenable to catheter-based or surgical interventions. Efforts to harmonize the definitions, staging, follow-up, and approach to heart failure in children with congenital heart disease are critical to enable the conduct of rigorous scientific studies to advance our understanding of the actual burden of heart failure in this population and to allow the development of evidence-based heart failure therapies that can improve outcomes for this high-risk cohort.

Sex-Related Differences and Influence of Pregnancy in Transposition of Great Arteries With Systemic Right Ventricle

Background

There is a paucity of data regarding sex-related differences on cardiac outcomes in the context of transposition of the great arteries (TGA) with a systemic right ventricle and biventricular physiology (sRV-biV). Moreover, the long-term impact of pregnancy on cardiac outcomes remains unknown.

Objectives

The purpose of this study was to identify sex-related differences and the influence of pregnancy on cardiac outcomes in TGA sRV-biV population.

Methods

A retrospective cohort study was conducted on 213 adults with TGA sRV-biV, 82 (38.4%) women, age 42.6 ± 12.8 years, with a median follow-up of 16 years. Cardiac events, interventions, last follow-up sRV-biV dysfunction, and heart failure (HF) medications were compared between men vs women, and women with vs without pregnancies resulting in live births.

Results

Women had a lower incidence of nonsustained ventricular tachycardia (HR: 1.80; 95% CI: 1.04-3.09, P = 0.035) and nonsignificantly fewer HF-related hospitalizations than men (HR: 2.10; 95% CI: 0.95-4.67, P = 0.069) in univariable analysis. At the last follow-up, women had a lower prevalence of moderate to severe sRV-biV dysfunction than men (P < 0.001) and were less frequently prescribed HF therapy. Women had fewer implantable cardioverter-defibrillators for primary prevention than men (P = 0.016), with no difference for secondary prevention. Women who had pregnancies resulting in live births (N = 47), had a high prevalence of cardiac events in the 15 (IQR: 9-28) years following pregnancy with no significant differences with those without (N = 32) pregnancies.

Conclusions

Women with a sRV-biV have fewer adverse cardiovascular events than men. Due to sRV-biV, pregnancy remains with high maternal risk but is not associated with worse long-term cardiac outcomes under rigorous multidisciplinary cardio-obstetrical care.

Robotic right ventricle is a biohybrid platform that simulates right ventricular function in (patho)physiological conditions and intervention

The increasing recognition of the right ventricle (RV) necessitates the development of RV-focused interventions, devices and testbeds. In this study, we developed a soft robotic model of the right heart that accurately mimics RV biomechanics and hemodynamics, including free wall, septal and valve motion. This model uses a biohybrid approach, combining a chemically treated endocardial scaffold with a soft robotic synthetic myocardium. When connected to a circulatory flow loop, the robotic right ventricle (RRV) replicates real-time hemodynamic changes in healthy and pathological conditions, including volume overload, RV systolic failure and pressure overload. The RRV also mimics clinical markers of RV dysfunction and is validated using an in vivo porcine model. Additionally, the RRV recreates chordae tension, simulating papillary muscle motion, and shows the potential for tricuspid valve repair and replacement in vitro. This work aims to provide a platform for developing tools for research and treatment for RV pathophysiology.

Abnormal developmental trajectory and vulnerability to cardiac arrhythmias in tetralogy of Fallot with DiGeorge syndrome

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. Ventricular dysfunction and cardiac arrhythmias are well-documented complications in patients with repaired TOF. Whether intrinsic abnormalities exist in TOF cardiomyocytes is unknown. We establish human induced pluripotent stem cells (hiPSCs) from TOF patients with and without DiGeorge (DG) syndrome, the latter being the most commonly associated syndromal association of TOF. TOF-DG hiPSC-derived cardiomyocytes (hiPSC-CMs) show impaired ventricular specification, downregulated cardiac gene expression and upregulated neural gene expression. Transcriptomic profiling of the in vitro cardiac progenitors reveals early bifurcation, as marked by ectopic RGS13 expression, in the trajectory of TOF-DG-hiPSC cardiac differentiation. Functional assessments further reveal increased arrhythmogenicity in TOF-DG-hiPSC-CMs. These findings are found only in the TOF-DG but not TOF-with no DG (ND) patient-derived hiPSC-CMs and cardiac progenitors (CPs), which have implications on the worse clinical outcomes of TOF-DG patients.

Free-Breathing and Single-Breath Hold Compressed Sensing Real-Time MRI of Right Ventricular Function in Children with Congenital Heart Disease

(1) Purpose: to compare right ventricular (RV) functional parameters in children with surgically repaired congenital heart disease (CHD) using single/double breath hold (BH) and free-breathing (FB) real-time compressed sensing (CS) cine cardiac magnetic resonance (cMRI) with standard retrospective segmented multi breath hold (RMB) cine cMRI. (2) Methods: Twenty patients with CHD underwent BH and FB, as well as RMB cine cMRI, at 3T to obtain a stack of continuous axial images of the RV. Two radiologists independently performed qualitative analysis of the image quality (rated on a 5-point scale; 1 = non-diagnostic to 5 = excellent) and quantitative analysis of the RV volume measurements. (3) Results: The best image quality was provided by RMB (4.5; range 2-5) compared to BH (3.9; range 3-5; p = 0.04) and FB (3.6; range 3-5; p < 0.01). The RV functional parameters were comparable among BH, FB, and RMB with a difference of less than 5%. The scan times for BH (44 ± 38 s, p < 0.01) and FB (24 ± 7 s, p < 0.01) were significantly reduced compared to for RMB (261 ± 68 s). (4) Conclusions: CS-FB and CS-BH real-time cine cMRI in children with CHD provides diagnostic image quality with excellent accuracy for measuring RV function with a significantly reduced scan time compared to RMB.

Design of the rospective Comparison of ngiotensin eceptor-Neprilysin Inhibitor Versus Plcebo in Patients With ongenital stemic ight entricle Heart Failure (PARACYS-RV) Trial

The presence of a systemic right ventricle (sRV) with biventricular physiology (biV) is associated with increased patient morbidity and mortality. To date, no pharmacologic therapy for heart failure has been proven effective for patients with systolic dysfunction of the sRV-biV. We designed a randomized, double-blind, placebo-controlled crossover trial to compare sacubitril/valsartan treatment to placebo in adults (aged ≥ 18 years) with moderate-to-severe sRV-biV dysfunction and New York Heart Association functional class II to III symptoms. Two primary efficacy endpoints are assessed in the trial: exercise capacity (submaximal exercise duration) and neurohormonal activation (N-terminal prohormone brain natriuretic peptide). Secondary objectives include assessing a change in the Kansas City Cardiomyopathy Questionnaire score and evaluating the safety and tolerance of sacubitril/valsartan. A 6-week open run-in phase identifies the maximum tolerated dose of sacubitril/valsartan, up to 97 mg/103 mg twice daily. After a 2-week washout period, patients are randomized 1:1 to sacubitril/valsartan treatment vs placebo for a 24-week phase, followed by another 2-week washout period and subsequent crossover to the alternative treatment arm for an additional 24-week phase. Data to assess primary and secondary endpoints are collected at baseline and at the end of each phase. A total of 48 patients is required to provide > 80% power to detect a 30% difference in distance walked and in N-terminal prohormone brain natriuretic peptide levels with sacubitril/valsartan treatment vs placebo, each with a 2-sided P-value of 0.025. In summary, the Prospective Comparison of Angiotensin Receptor-Neprilysin Inhibitor vs Placebo in Patients With Congenital Systemic Right Ventricular Heart Failure Trial (PARACYS-RV) should determine the role of sacubitril/valsartan in treating heart failure in patients with sRV-biV and carries the potential to alter management of this patient population.

A comparison between the apical and subcostal view for three-dimensional echocardiographic assessment of right ventricular volumes in pediatric patients

Background

Accurate measurement of ventricular volumes is an important clinical imaging goal. Three-dimensional echocardiography (3DEcho) is used increasingly as it is more available and less costly than cardiac magnetic resonance (CMR). For the right ventricle (RV), the current practice is to acquire 3DEcho volumes from the apical view. However, in some patients the RV may be better seen from the subcostal view. Therefore, this study compared RV volume measurements from the apical vs. the subcostal view, using CMR as a reference standard.

Methods

Patients <18 years old undergoing a clinical CMR examination were prospectively enrolled. 3DEcho was performed on the day of the CMR. 3DEcho images were acquired with Philips Epic 7 ultrasound system from apical and subcostal views. Offline analysis was performed with TomTec 4DRV Function for 3DEcho images and cvi42 for CMR ones. RV end-diastolic volume and end-systolic volume were collected. Agreement between 3DEcho and CMR was assessed with Bland-Altman analysis and the intraclass correlation coefficient (ICC). Percentage (%) error was calculated using CMR as the reference standard.

Results

Forty-seven patients were included in the analysis (age range 10 months to 16 years). The ICC was moderate to excellent for all volume comparisons to CMR (subcostal vs. CMR: end-diastolic volume 0.93, end-systolic volume 0.81; apical vs. CMR: end-diastolic volume 0.94, end-systolic volume 0.74).The 3DEcho mean % error vs. CMR for end-systolic volume was 25% for subcostal and 31% for apical; for end-diastolic volume it was 15% for subcostal and 16% for apical. The % error was not significantly different between apical vs. subcostal views for end-systolic and end-diastolic volume measurements.

Conclusions

For apical and subcostal views, 3DEcho-derived ventricular volumes agree well with CMR. Neither echo view has a consistently smaller error when compared to CMR volumes. Accordingly, the subcostal view can be used as an alternative to the apical view when acquiring 3DEcho volumes in pediatric patients, particularly when the image quality from this window is superior.

Biomarker sST2 in Adults with Transposition of the Great Arteries Palliated by Mustard Procedure: A Five-Year Follow-up

The Mustard procedure was an early cardiac surgery for transposition of the great arteries (TGA). Despite being successful, it has been associated with long-term arrhythmias and heart failure. A key factor complicating management in adults with congenital heart disease (CHD) is the deficiency of biomarkers predicting outcome. Soluble suppression of tumorogenicity-2 (sST2) is secreted by cardiomyocytes in response to mechanical strain and fibrosis. We hypothesized that adults with a Mustard procedure would have higher levels of sST2 than healthy individuals, and this would correlate with clinical outcome. We performed a single-center study in patients managed during childhood with a Mustard procedure versus age-matched controls. Clinical and demographic data were collected and biomarkers (sST2, cTnI, BNP, lipid panel, insulin, and glucose) were obtained. There were 18 patients (12 male) in the Mustard cohort and 18 patients (6 male) in the control group (22-49 years, mean of 35.8 vs. mean 32.6 years, respectively, p = ns). Nine Mustard subjects were NYHA class II, and 9 subjects were class III. The control group was asymptomatic. sST2 in the Mustard group was elevated in 56% vs. 17% in controls (p = 0.035). Of the Mustard subjects with elevated sST2, 60% had elevated cTnI and BNP, and 90% had low HDL. Over five years, the Mustard patients with elevated sST2 values had greater medication use, arrhythmias, hospitalizations, and ablation/pacer implantations than Mustard subjects with normal sST2. Mustard subjects with elevated sST2 had other biomarker abnormalities and clinically worse outcomes. Thus, sST2 may add a predictive value to cardiac-related morbidity and mortality.

Prognostic Effects of Changes in Right Ventricular Fractional Area Change in Patients With Heart Failure

BACKGROUND

It is still unclear whether changes in right ventricular function are associated with prognosis in heart failure (HF) patients. This study aimed to examine the prognostic effect of changes in right ventricular fractional area change (RVFAC).

METHODS AND RESULTS

This study enrolled 480 hospitalized patients with decompensated HF, and measured RVFAC with echocardiography at discharge (first examination) and post-discharge in the outpatient setting (second examination). RVFAC was divided into 3 categories: >35% in 314 patients, 25-35% in 108 patients, and <25% in 58 patients. Next, based on changes in RVFAC from the first to the second examination, the patients were further classed into 4 groups: (1) Preserved/Unchanged (preserved and unchanged RVFAC, n=235); (2) Reduced/Improved (improved RVFAC in at least 1 category, n=106); (3) Reduced/Unchanged (reduced and unchanged RVFAC, n=47); and (4) Preserved or Reduced/Worsened (deteriorated RVAFC in at least 1 category, n=92). Multivariate logistic regression analysis revealed that chronic kidney disease and anemia were the predictors of the preserved or reduced/worsened RVFAC. In the Kaplan-Meier analysis, changes in RVFAC were associated with the cardiac event rate and all-cause mortality. In the multivariable Cox proportional hazard analysis, the preserved or reduced/worsened RVFAC was an independent predictor of cardiac events and all-cause mortality.

CONCLUSIONS

Changes in RVFAC were associated with post-discharge prognosis in hospitalized heart failure patients.

The Right Ventricle: From Embryologic Development to RV Failure

PURPOSE OF REVIEW

The right ventricle (RV) and left ventricle (LV) have different developmental origins, which likely plays a role in their chamber-specific response to physiological and pathological stress. RV dysfunction is encountered frequently in patients with congenital heart disease (CHD) and right heart abnormalities emerge from different causes than increased afterload alone as is observed in RV dysfunction due to pulmonary hypertension (PH). In this review, we describe the developmental, structural, and functional differences between ventricles while highlighting emerging therapies for RV dysfunction.

RECENT FINDINGS

There are new insights into the role of fibrosis, inflammation, myocyte contraction, and mitochondrial dynamics in the pathogenesis of RV dysfunction. We discuss the current state of therapies that may potentially improve RV function in both experimental and clinical trials. A clearer understanding of the differences in molecular alterations in the RV compared to the LV may allow for the development of better therapies that treat RV dysfunction.

Ferumoxytol-enhanced 4D multiphase, steady-state imaging with magnetic resonance in congenital heart disease: ventricular volume and function across 2D and 3D software platforms

Background

Quantitative ventricular volumetry and function are important in the management of congenital heart disease (CHD). Ferumoxytol-enhanced (FE) 4D multiphase, steady state imaging with contrast enhancement (MUSIC) enables high-resolution, 3D cardiac phase-resolved magnetic resonance imaging (MRI) of the beating heart and extracardiac vessels in a single acquisition and without concerns about renal impairment. We aim to evaluate the semi-automatic quantification of ventricular volumetry and function of 4D MUSIC MRI using 2D and 3D software platforms.

Methods

This HIPAA-compliant and IRB-approved study prospectively recruited 50 children with CHD (3 days to 18 years) who underwent 4D MUSIC MRI at 3.0T between 2013-2017 for clinical indications. Each patient was either intubated in the neonatal intensive care unit (NICU) or underwent general anesthesia at MRI suite. For 2D analysis, we reformatted MUSIC images in Digital Imaging and Communications in Medicine (DICOM) format into ventricular short-axis slices with zero interslice gap. For 3D analysis, we imported DICOMs into a commercially available 3D software platform. Using semi-automatic thresholding, we quantified biventricular volume and ejection fraction (EF). We assessed the bias between MUSIC-derived 2D vs. 3D measurements and correlation between MUSIC vs. conventional 2D balanced steady-state free precession (bSSFP) cine images. We evaluated intra- and inter-observer agreement.

Results

There was a high degree of correlation between MUSIC-derived volumetric and functional measurements using 2D vs. 3D software (r=0.99, P<0.001). Volumes derived using 3D software platforms were larger than 2D by 0.2 to 2.0 mL/m2 whereas EF measurements were higher by 1.2-3.0%. MUSIC volumetric and functional measures derived from 2D and 3D software platforms corresponded highly with those derived from multi-slice SSFP cine images (r=0.99, P<0.001). The mean difference in volume for reformatted 4D MUSIC relative to bSSFP cine was 1.5 to 3.9 mL/m2. Intra- and inter-observer reliability was excellent.

Conclusions

Accurate and reliable ventricular volumetry and function can be derived from FE 4D MUSIC MRI studies using commercially available 2D and 3D software platforms. If fully validated in multicenter studies, the FE 4D-MUSIC pulse sequence may supercede conventional multislice 2D cine cardiovascular MRI acquisition protocols for functional evaluation of children with complex CHD.

Right ventricular failure: a comorbidity or a clinical emergency?

There has been ample data providing a convincing perception about the underlying mechanism pertaining to left ventricle (LV) hypertrophy progressing towards LV failure. In comparison, data available on the feedback of right ventricle (RV) due to volume or pressure overload is minimal. Advanced imaging techniques have aided the study of physiology, anatomy, and diseased state of RV. However, the treatment scenario of right ventricular failure (RVF) demands more attention. It is a critical clinical risk in patients with carcinoid syndrome, pulmonary hypertension, atrial septal defect, and several other concomitant diseases. Although the remodeling responses of both ventricles on an increase of end-diastolic pressure are mostly identical, the stressed RV becomes more prone to oxidative stress activating the apoptotic mechanism with diminished angiogenesis. This instigates the advancement of RV towards failure in contrast to LV. Empirical heart failure (HF) therapies have been ineffective in improving the mortality rate and cardiac function in patients, which prompted a difference between the underlying pathophysiology of RVF and LV failure. Treatment strategies should be devised, taking into consideration the anatomical and physiological characteristics of RV. This review would emphasize on the pathophysiology of the RVF and the differences between two ventricles in molecular response to stress. A proper insight into the underlying pathophysiology is required to develop optimized therapeutic management in RV-specific HF.

A finite element model of the cardiac ventricles with coupled circulation: Biventricular mesh generation with hexahedral elements, airbags and a functional mockup interface to the circulation

INTRODUCTION

Finite element (FE) mechanics models of the heart are becoming more sophisticated. However, there is lack of consensus about optimal element type and coupling of FE models to the circulation. We describe biventricular (left (LV) and right (RV) ventricles) FE mechanics model creation using hexahedral elements, airbags and a functional mockup interface (FMI) to lumped-parameter models of the circulation.

METHODS

Cardiac MRI (CMR) was performed in two healthy volunteers and a single patient with ischemic heart disease (IHD). CMR images were segmented and surfaced, meshing with hexahedral elements was performed with a "thin butterfly with septum" topology. LV and RV inflow and outflow airbags were coupled to lumped-parameter circulation models with an FMI interface. Pulmonary constriction (PAC) and vena cava occlusion (VCO) were simulated and end-systolic pressure-volume relations (ESPVR) were calculated.

RESULTS

Mesh construction was prompt with representative contouring and mesh adjustment requiring 32 and 26 min Respectively. The numbers of elements ranged from 4104 to 5184 with a representative Jacobian of 1.0026 ± 0.4531. Agreement between CMR-based surfaces and mesh was excellent with root-mean-squared error of 0.589 ± 0.321 mm. The LV ESPVR slope was 3.37 ± 0.09 in volunteers but 2.74 in the IHD patient. The effect of PAC and VCO on LV ESPVR was consistent with ventricular interaction (p = 0.0286).

CONCLUSION

Successful co-simulation using a biventricular FE mechanics model with hexahedral elements, airbags and an FMI interface to lumped-parameter model of the circulation was demonstrated. Future studies will include comparison of element type and study of cardiovascular pathologies and device therapies.

Perioperative Right Ventricular Dysfunction: Analysis of Outcomes

Right ventricular dysfunction (RVD) is a well-known prognostic factor for adverse outcomes in cardiovascular medicine. The right ventricle (RV) in medically managed heart failure patients and in surgical patients perioperatively generally is overshadowed by left ventricular disease. However, with advancement of various diagnostic tools and better understanding of its functional anatomy, the role of the RV is emerging in many clinical conditions. The failure of one ventricle has significant effect on the function of the other ventricle and it is predominantly due to ventricular interdependence.¹ The etiology of RVD is multifactorial and irrespective of etiology. RVD has been associated with significant increases in morbidity and mortality in various clinical scenarios.^2,3 The primary objective of this comprehensive review is to analyze various etiology-related outcomes of RVD in the perioperative population.

Elabela: A Novel Biomarker for Right Ventricular Pressure Overload in Children With Pulmonary Stenosis or Pulmonary Atresia With Intact Ventricular Septum

Background: Assessing right ventricular overload in children is challenging. We conducted this study involving children with pulmonary valvular stenosis (PS) or pulmonary atresia with intact ventricular septum (PA/IVS) to evaluate the potential of a new endogenous ligand of apelin receptor, Elabela (ELA), as a potential biomarker for right heart overload.

Methods: In this prospective cohort study, a total of 118 congenital heart diseases patients with right ventricle outflow tract obstruction were recruited from 2018 to 2019. Among them, 44 isolated PS and 7 PA/IVS patients were selected. Their venous blood was collected, and all patients underwent an echocardiographic examination. Among them, post-operative blood was collected from 24 patients with PS after percutaneous balloon pulmonary valvuloplasty. The plasma ELA concentration was measured using enzyme-linked immunosorbent assay.

Results: The ELA was significantly associated with the peak transvalvular pulmonary gradient (r = −0.62; p = 0.02), thus reflecting the severity of PS or PA/IVS. The ELA significantly increased at 3 days after intervention, when mechanical obstruction of the right outflow tract was relieved. Based on the receiver-operator characteristic curve results, ELA could be a risk factor for duct dependence in patients with critical PS or PA/IVS who are younger than 6 months (AUC: 0.82).

Conclusion: ELA concentration and severity of PS or PA/IVS had a significant negative correlation, indicating that ELA might be a novel biomarker for right ventricular afterload and reflect the immediate pressure changes in the right heart. Furthermore, ELA could predict duct-dependency in PS and PA/IVS patients, as valuable as classical echocardiographic indexes.

Inferior Right Ventricular Wall Thickness by Echocardiogram: A Novel Method of Assessing Hypertrophy in Neonates and Infants

An established echocardiographic (echo) standard for assessing the newborn right ventricle (RV) for hypertrophy has not been thoroughly developed. This is partially due to the RV's complex architecture, which makes quantification of RV mass by echo difficult. Here, we retrospectively evaluate the thickness of the inferior RV wall (iRVWT) by echo in neonates and infants with normal cardiopulmonary physiology. Inferior RVWT was defined at the medial portion of the inferior wall of the RV at the mid-ventricular level, collected from a subxiphoid, short axis view. iRVWT was indexed to body surface area (BSA) to the 0.5 power and normalized to iLVWT to explore the best normalization method. Ninety-eight neonates and 32 infants were included in the final analysis. Mean age for neonates and infants was 2 days and 59 days, respectively. Mean ± SD for neonate and infant end-diastole iRVWT was 2.17 ± 0.35 mm and 1.79 ± 0.28 mm, respectively. There was no residual relationship between the index iRVWT and BSA (r = 0.03, p = NS). In the infant cohort, the iRVWT was significantly lower and iLVWT was significantly higher compared to neonate, consistent with known physiologic changes of RV and LV mass. Thus, iRVWT may serve as a reliable and accurate proxy for RV mass and the parameter warrants further evaluation.

Quantitative assessment of contractile reserve of systemic right ventricle in post-Senning children: Incorporating speckle-tracking strain and dobutamine stress echocardiography

INTRODUCTION

The systemic load on the right ventricle (RV) after Senning atrial switch leads to ventricular dysfunction. Quantitative assessment of RV contractile reserve is mandatory to anticipate the need for anti-fibrotic treatment. We aimed to quantitatively assess RV contractile reserve in Senning children by estimating speckle-based global longitudinal strain (GLS) during dobutamine stress echocardiography (DSE).

METHODS

This prospective study compared thirty-one post-Senning children (group I) and thirty controls (group II). In post-Senning children, echocardiographic RV systolic function using one-plane ejection fraction (RVEF), RV fractional area change (RVFAC), tricuspid annulus plane systolic excursion (TAPSE), its Z-score, and RVGLS were recorded at rest and peak DSE. Contractile reserve was defined as improvement >5% in RVEF, >2% in GLS, and/or to near normal TAPSE.

RESULTS

RVEF, RVFAC, TAPSE, and TAPSE Z-score were significantly lower in patients than controls [RVEF:40.13 ± 2.93% vs 53.17 ± 3.17% (P < .001*), RVFAC: 21.17 ± 2.37% vs 37.23 ± 2.13% (P < .001*), TAPSE:13.81 ± 1.26 vs 17.45 ± 2.93 mm (P < .001*), TAPSE Z-score: -3.47 ± 0.46 vs -2.09 ± 0.48 (P < .001*)]. Also, RVGLS was significantly impaired in Senning children than controls[ (-11.89 ± 2.31% vs -22.35 ± 6.73% (P < .001*)]. At peak DSE, contractile reserve was not evident as measured by RVEF which increased none significantly to 42.47 ± 2.80% (P = .063). However, RVGLS improved significantly to -15.78 ± 0.93% (P < .001*) and discovered the masked contractile reserve in Senning children. The 19(61.29%) children who showed masked contractile reserve (improvement in RVGLS > 2%) underwent continuation of anti-fibrotic medications.

CONCLUSIONS

Despite systemic RV function in post-Senning children was impaired at rest and during DSE, RVGLS was useful in quantitative assessment of masked contractile thus promoted continuing anti-fibrotic treatment.

Utility of machine learning algorithms in assessing patients with a systemic right ventricle

AIMS

To investigate the utility of novel deep learning (DL) algorithms in recognizing transposition of the great arteries (TGA) after atrial switch procedure or congenitally corrected TGA (ccTGA) based on routine transthoracic echocardiograms. In addition, the ability of DL algorithms for delineation and segmentation of the systemic ventricle was evaluated.

METHODS AND RESULTS

In total, 132 patients (92 TGA and atrial switch and 40 with ccTGA; 60% male, age 38.3 ± 12.1 years) and 67 normal controls (57% male, age 48.5 ± 17.9 years) with routine transthoracic examinations were included. Convolutional neural networks were trained to classify patients by underlying diagnosis and a U-Net design was used to automatically segment the systemic ventricle. Convolutional networks were build based on over 100 000 frames of an apical four-chamber or parasternal short-axis view to detect underlying diagnoses. The DL algorithm had an overall accuracy of 98.0% in detecting the correct diagnosis. The U-Net architecture model correctly identified the systemic ventricle in all individuals and achieved a high performance in segmenting the systemic right or left ventricle (Dice metric between 0.79 and 0.88 depending on diagnosis) when compared with human experts.

CONCLUSION

Our study demonstrates the potential of machine learning algorithms, trained on routine echocardiographic datasets to detect underlying diagnosis in complex congenital heart disease. Automated delineation of the ventricular area was also feasible. These methods may in future allow for the longitudinal, objective, and automated assessment of ventricular function.

Autogenous mitochondria transplantation for treatment of right heart failure

BACKGROUND

Right ventricular hypertrophy and failure are major causes of cardiac morbidity and mortality. A key event in the progression to right ventricular hypertrophy and failure is cardiomyocyte apoptosis due to mitochondrial dysfunction. We sought to determine whether localized intramyocardial injection of autologous mitochondria from healthy muscle treats heart failure.

METHODS

Mitochondria transplanted from different sources were initially tested in cultured hypertrophic cardiomyocytes. A right ventricular hypertrophy/right ventricular failure model created through banding of the pulmonary artery in immature piglets was used for treatment with autologous mitochondria (pulmonary artery banded mitochondria injected/treated n = 6) from calf muscle, versus vehicle (pulmonary artery banded vehicle injected/treated n = 6) injected into the right ventricular free-wall, and compared with sham-operated controls (sham, n = 6). Animals were followed for 8 weeks by echocardiography (free-wall thickness, contractility), and dp/dt max was measured concomitantly with cardiomyocyte hypertrophy, fibrosis, and apoptosis at study end point.

RESULTS

Internalization of mitochondria and adenosine triphosphate levels did not depend on the source of mitochondria. At 4 weeks, banded animals showed right ventricular hypertrophy (sham: 0.28 ± 0.01 cm vs pulmonary artery banding: 0.4 ± 0.02 cm wall thickness; P = .001), which further increased in pulmonary artery banded mitochondria injected/treated but declined in pulmonary artery banded vehicle injected/treated (0.47 ± 0.02 cm vs 0.348 ± 0.03 cm; P = .01). Baseline contractility was not different but was significantly reduced in pulmonary artery banded vehicle injected/treated compared with pulmonary artery banded mitochondria injected/treated and so was dp/dtmax. There was a significant difference in apoptotic cardiomyocyte loss and fibrosis in sham versus hypertrophied hearts with most apoptosis in pulmonary artery banded vehicle injected/treated hearts (sham: 1 ± 0.4 vs calf muscle vs vehicle: 13 ± 1.7; P = .001 and vs pulmonary artery banded mitochondria injected/treated: 8 ± 1.9, P = .01; pulmonary artery banded vehicle injected/treated vs pulmonary artery banded mitochondria injected/treated, P = .05).

CONCLUSIONS

Mitochondrial transplantation allows for prolonged physiologic adaptation of the pressure-loaded right ventricular and preservation of contractility by reducing apoptotic cardiomyocyte loss.

MRI Assessment of Right Ventricular Volumes and Function in Patients With Repaired Tetralogy of Fallot Using kat-ARC Accelerated Sequences

OBJECTIVE. The objective of our study was to assess the accuracy and reproducibility of right ventricular volumes and function measurements in patients with repaired tetralogy of Fallot using two k-adaptive-t autocalibrating reconstruction for cartesian sampling (kat-ARC) accelerated sequences: a morphologic 3D cine sequence and a functional free-breathing 4D flow sequence. SUBJECTS AND METHODS. Seventeen patients who underwent cardiac MRI with gadolinium injection as part of follow-up of repaired tetralogy of Fallot from March 2017 to July 2018 were prospectively included in the initial study population; the final study cohort was composed of 15 of the 17 patients. Ventricle volume measurements were performed on a 3D cine kat-ARC sequence, a 4D flow kat-ARC sequence, and a 2D cine balanced steady-state free precession (bSSFP) sequence. The 2D cine bSSFP sequence was the reference standard in cardiac assessment. Intertechnique and interobserver analyses were performed. Bland-Altman analysis and correlation tests were used to compare quantitative measurements. RESULTS. Ventricular end-diastolic volume (EDV) and end-systolic volume (ESV) values were well correlated in the right ventricle (r = 0.94-0.98) for both 3D and 4D sequences. Ejection fraction (EF) also showed good correlation for both 3D and 4D sequences (r = 0.79 and r = 0.92). Bland-Altman analysis showed good agreement between right and left ventricular volumes, with narrower limits of agreement in the left ventricle, and an intraclass correlation coefficient (ICC) of greater than 0.80. For the 4D flow sequence, ventricular volumes were overestimated, which led to underestimation of the EF (bias for EDV = -10.2 mL, bias for ESV = -22.7 mL, bias for EF = 6.4%). Interobserver agreement was excellent for the ventricular volumes (ICC, 0.93-0.99) and fair to excellent for the EFs (ICC, 0.59-0.83). CONCLUSION. Compared with the reference standard 2D bSSFP sequence, the 3D cine kat-ARC accelerated sequence showed good accuracy and reproducibility for right ventricular measurements in patients with repaired tetralogy of Fallot. The short duration of the 4D flow kat-ARC sequence appears promising for performing volumetric measurements.

Development of novel machine learning model for right ventricular quantification on echocardiography-A multimodality validation study

Purpose

Echocardiography (echo) is widely used for right ventricular (RV) assessment. Current techniques for RV evaluation require additional imaging and manual analysis; machine learning (ML) approaches have the potential to provide efficient, fully automated quantification of RV function.

Methods

An automated ML model was developed to track the tricuspid annulus on echo using a convolutional neural network approach. The model was trained using 7791 image frames, and automated linear and circumferential indices quantifying annular displacement were generated. Automated indices were compared to an independent reference of cardiac magnetic resonance (CMR) defined RV dysfunction (RVEF < 50%).

Results

A total of 101 patients prospectively underwent echo and CMR: Fully automated annular tracking was uniformly successful; analyses entailed minimal processing time (<1 second for all) and no user editing. Findings demonstrate all automated annular shortening indices to be lower among patients with CMR‐quantified RV dysfunction (all P < .001). Magnitude of ML annular displacement decreased stepwise in relation to population‐based tertiles of TAPSE, with similar results when ML analyses were localized to the septal or lateral annulus (all P ≤ .001). Automated segmentation techniques provided good diagnostic performance (AUC 0.69–0.73) in relation to CMR reference and compared to conventional RV indices (TAPSE and S′) with high negative predictive value (NPV 84%–87% vs 83%–88%). Reproducibility was higher for ML algorithm as compared to manual segmentation with zero inter‐ and intra‐observer variability and ICC 1.0 (manual ICC: 0.87–0.91).

Conclusions

This study provides an initial validation of a deep learning system for RV assessment using automated tracking of the tricuspid annulus.

The role of mechanotransduction in heart failure pathobiology-a concise review

This review evaluates the role of mechanotransduction (MT) in heart failure (HF) pathobiology. Cardiac functional and structural modifications are regulated by biomechanical forces. Exposing cardiomyocytes and the myocardial tissue to altered biomechanical stress precipitates changes in the end-diastolic wall stress (EDWS). Thereby various interconnected biomolecular pathways, essentially mediated and orchestrated by MT, are launched and jointly contribute to adapt and remodel the myocardium. This cardiac MT-mediated feedback decisively determines the primary cardiac cellular and tissue response, the sort (concentric or eccentric) of hypertrophy/remodeling, to mechanical and/or hemodynamic alterations. Moreover, the altered EDWS affects the diastolic myocardial properties independent of the systolic function, and elevated EDWS causes diastolic dysfunction. The close interconnection between MT pathways and the cell nucleus, the genetic endowment, principally allows for the wide variety of phenotypic appearances. However, demographic, environmental features, comorbidities, and also the genetic make-up may modulate the phenotypic result. Cardiac MT takes a fundamental and superordinate position in the myocardial adaptation and remodeling processes in all HF categories and phenotypes. Therefore, the effects of MT should be integrated in all our scientific, clinical, and therapeutic considerations.

Myocardial perfusion abnormalities in Eisenmenger syndrome

BACKGROUND

Compared to primary pulmonary hypertension (PPH), the right ventricular (RV) contractile function is preserved for a long time in patients with Eisenmenger syndrome and is likely the most important determinant of relatively higher survival. The differences in myocardial perfusion have been purported to explain this discrepancy. The exact prevalence of myocardial perfusion abnormalities in Eisenmenger syndrome is not known. We sought to examine the prevalence of myocardial perfusion abnormalities in patients with Eisenmenger syndrome.

METHODS

In this prospective study, 20 consecutive adult patients with Eisenmenger syndrome were subjected to clinical assessment, six-minute walk test and echocardiography. Myocardial perfusion was assessed using one day stress-rest Gated Technetium-99 m Sestamibi single-photon emission computed tomography.

RESULTS

Nineteen (95%) patients were in New York Heart Association functional class I or II. All patients had RV hypertrophy. Five (25%) patients had RV systolic dysfunction. Left ventricular systolic function was normal in all except in three patients. Two (10%) patients had perfusion defects in the RV and 4 (20%) patients had perfusion defects in the left ventricle (LV).

CONCLUSION

Myocardial perfusion defects, both in RV and LV, occur even in asymptomatic or mildly symptomatic patients with Eisenmenger syndrome.

Tricuspid regurgitation severity after atrial septal defect closure or pulmonic valve replacement

Objectives

Cardiac surgery or catheter interventions are nowadays commonly performed to reduce volume loading of the right ventricle in adults with congenital heart disease. However, little is known, on the effect of such procedures on pre-existing tricuspid regurgitation (TR). We assessed the potential reduction in the severity of TR after atrial septal defect (ASD) closure and pulmonic valve replacement (PVR).

Methods

Demographics, clinical and echocardiographic characteristics of consecutive patients undergoing ASD closure or PVR between 2005 and 2014 at a single centre who had at least mild preoperative TR were collected and analysed.

Results

Overall, 162 patients (mean age at intervention 41.6±16.1 years, 38.3% male) were included: 101 after ASD closure (61 transcatheter vs 40 surgical) and 61 after PVR (3 transcatheter vs 58 surgical). Only 11.1% received concomitant tricuspid valve surgery (repair). There was significant reduction in the severity of TR in the overall population, from 38 (23.5%) patients having moderate or severe TR preoperatively to only 11 (6.8%) and 20 (12.3%) at 6 months and 12 months of follow-up, respectively (McNemar p<0.0001). There was a significant reduction in tricuspid valve annular diameter (p<0.0001), coaptation distance (p<0.0001) and systolic tenting area (p<0.0001). The reduction in TR was also observed in patients who did not have concomitant tricuspid valve (TV) repair (from 15.3% to 6.9% and 11.8% at 6 and 12 months, respectively, p<0.0001). On multivariable logistic regression including all univariable predictors of residual TR at 12 months, only RA area remained in the model (OR 1.2, 95% CI 1.04 to 1.37, p=0.01).

Conclusions

ASD closure and PVR are associated with a significant reduction in tricuspid regurgitation, even among patients who do not undergo concomitant tricuspid valve surgery.

Resolving the natural myocardial remodelling brought upon by cardiac contraction; a porcine ex-vivo cardiovascular magnetic resonance study of the left and right ventricle

BACKGROUND

The three-dimensional rearrangement of the right ventricular (RV) myocardium during cardiac deformation is unknown. Previous in-vivo studies have shown that myocardial left ventricular (LV) deformation is driven by rearrangement of aggregations of cardiomyocytes that can be characterised by changes in the so-called E3-angle. Ex-vivo imaging offers superior spatial resolution compared with in-vivo measurements, and can thus provide novel insight into the deformation of the myocardial microstructure in both ventricles. This study sought to describe the dynamic changes of the orientations of the cardiomyocytes in both ventricles brought upon by cardiac contraction, with particular interest in the thin-walled RV, which has not previously been described in terms of its micro-architecture.

METHODS

The hearts of 14 healthy 20 kg swine were excised and preserved in either a relaxed state or a contracted state. Myocardial architecture was assessed and compared between the two contractional states by quantification of the helical, transmural and E3-angles of the cardiomyocytes using high-resolution diffusion tensor imaging.

RESULTS

The differences between the two states of contraction were most pronounced in the endocardium where the E3-angle decreased from 78.6° to 24.8° in the LV and from 82.6° to 68.6° in the RV. No significant change in neither the helical nor the transmural angle was found in the cardiomyocytes of the RV. In the endocardium of the LV, however, the helical angle increased from 35.4° to 47.8° and the transmural angle increased from 3.1° to 10.4°.

CONCLUSION

The entire myocardium rearranges through the cardiac cycle with the change in the orientation of the aggregations of cardiomyocytes being the predominant mediator of myocardial wall thickening. Interestingly, differences also exist between the RV and LV, which helps in the explanation of the different physiological capabilities of the ventricles.

Clinical Evaluation of Exercise Capacity in Adults with Systemic Right Ventricle

The right ventricle provides systemic circulation in individuals with congenitally corrected transposition of the great arteries (CCTGA) and in those with complete transposition who have had an atrial switch repair (DTGA). The aim of this study was to evaluate how the systemic right ventricle adapts to increased workload and oxygen demand during exercise. From November 2005 through December 2015, 3,358 adult patients with congenital heart disease were treated at our institution; we identified 48 (26 females, 22 males; median age, 25.4 ± 8.1 yr) who met the study criteria; 37 had DTGA and atrial switch repair, and 11 had CCTGA. We studied their echocardiographic and cardiopulmonary exercise test results. A control group consisted of 29 healthy sex- and age-matched volunteers. On exercise testing, oxygen uptake at anaerobic threshold, peak oxygen uptake, peak heart rate, and percentage of maximal heart rate were significantly lower in the group with systemic right ventricle than in the control group (all P <0.001); in contrast, the peak ventilatory equivalent for carbon dioxide was higher in the study group (P=0.013). Impaired systemic right ventricular function reduced peak oxygen uptake. The peak heart rate was lower in the CCTGA group than in the DTGA group. Our results indicate that reduced exercise capacity is related to impaired systemic right ventricular function, severe tricuspid valve regurgitation, and chronotropic incompetence. There was no correlation between cardiopulmonary exercise test results and time after surgery. Chronotropic efficiency is lower in individuals with CCTGA than in those with DTGA.

Stent angioplasty of narrowed right ventricular outflow conduits and pulmonary arteries consistently reduces right ventricular systolic pressures and delays subsequent surgeries

Objectives

Narrowed right ventricular (RV) outflow conduits and pulmonary arteries (PA) increase RV pressures and warrant interventions. Stent angioplasty is an alternative to more morbid redo-surgery in developing countries. We evaluate the efficacy and safety of stenting and assess need for redo-surgical reinterventions on midterm follow-up after stent angioplasty.

Methods

Patients who underwent conduit, main PA and bilateral branch PA stenting for elevated RV pressures were analyzed retrospectively. Success was defined as 20% reduction in RV pressures or RV-aortic pressure ratio; 50% reduction in gradients or 50% increase of luminal diameter. Procedural results, complications and need for redo surgeries on follow-up were assessed.

Results

Among 60 patients aged 1–46 years, 57 were post-operative patients, who needed stenting at a median period of 48 months after surgery. Stenting succeeded in 98% and reduced RV pressures from 105.42 ± 28.39 mmHg to 54.46 ± 16.89 mmHg. Direct major procedural complications in five (8%) patients included procedural failure in one, stent migration in three and lung hemorrhage in one. None of the stented conduits needed a surgical change on a follow-up ranging 3–120 months. Following bilateral PA stenting in twenty-four patients, only two needed a repeat open-heart surgery during follow-up ranging 3–108 months. Catheter reinterventions on follow-up included elective percutaneous pulmonary valve implantation in nine patients and stent redilation in seven patients.

Conclusions

Stent angioplasty was safe and effective. Surgery was postponed in all stenosed conduits. Elective redilation of stents after bilateral PA stenting may be needed for somatic growth; but open-heart repeat surgeries can be avoided in a majority.

Variability in the Echocardiographic Evaluation of the Systemic Right Ventricle

BACKGROUND

Echocardiographic evaluation of the systemic right ventricle (sRV) remains challenging in patients with transposition of the great arteries (TGA) corrected by an atrial switch (AS) and with congenitally corrected TGA (ccTGA). The aim of this study was to determine the interobserver and intraobserver variability of echocardiographic parameters for sRV size and systolic function.

METHODS

Six independent observers retrospectively interpreted 44 previously acquired echocardiograms (25 patients with TGA/AS and 19 patients with ccTGA). Quantitative parameters included inlet and longitudinal diameters, systolic and diastolic areas, fractional area change (FAC), and wall thickness. sRV dilatation and systolic function were qualitatively graded as normal, mild, moderate, or severe. sRV hypertrophy was graded as present or absent. Intraclass correlation coefficients (ICCs) and Kappa statistics were computed to assess interobserver variability. Images from 10 patients (5 TGA/AS and 5 ccTGA) were reinterpreted at a 1-month interval, and ICC and Kendall tau b statistics were computed to assess intraobserver variability.

RESULTS

Interobserver and intraobserver agreement were good to excellent for sRV diameters, areas and FAC (ICC, 0.49-0.97), except for the sRV wall thickness (ICC < 0) and the FAC for 1 observer. Interobserver agreement was poor for the qualitative assessment of sRV size and systolic function (Kappa < 0.25), but with a good to excellent intraobserver agreement.

CONCLUSIONS

These findings suggest that overall appreciation of sRV size and systolic function relies on variable interpretation of measurements by observers. Readers experienced in CHD and with clear thresholds for quantitative parameters, along with a validated algorithm, are required to guide the evaluation of sRV.

Right Heart-Pulmonary Circulation Unit in Congenital Heart Diseases

The right ventricle plays a major role in congenital heart disease. This article describes the right ventricular mechanics in some selected congenital heart diseases affecting the right ventricle in different ways: tetralogy of Fallot, Ebstein anomaly, and the systemic right ventricle.

Afterload dependence of right ventricular myocardial deformation: A comparison between tetralogy of Fallot and atrially corrected transposition of the great arteries in adult patients

Background

Prior studies suggested that myocardial deformation is superior to conventional measures for assessing ventricular function. This study aimed to evaluate right ventricular (RV) myocardial deformation in response to increased afterload. Patients with the RV in the systemic position were compared with patients with the RV in the sub-pulmonic position with normal or only slightly elevated systolic right ventricular pressure. Correlations between global longitudinal strain (GLS), radial strain, atrioventricular plane displacement (AVPD), and exercise capacity were evaluated.

Methods

44 patients with congenital heart defect were enrolled in the study. The control group consisted of seven healthy volunteers. All patients underwent cardiovascular magnetic resonance (CMR) and cardiopulmonary exercise testing. We assessed biventricular myocardial function using CMR based feature tracking and compared the results to anatomic volumes.

Results

Strain analysis and displacement measurements were feasible in all participants. RVGLS and RVAVPD were reduced in both study groups compared to the control group (p<0.001). Left ventricular (LV) radial strain was significantly lower in patients with a systemic RV than in those with a subpulmonic RV and lower than in controls (p<0.001). Both LVAVPD and RVAVPD were significantly depressed in patients compared to controls (p<0.05). RVAVPD was more depressed in patients with a high systolic RV pressure than in those with normal RV pressure (p<0.001). RVAVPD did not correlate with exercise capacity in either study group. Exercise capacity in both patient groups was depressed to levels reported in previous studies, and did not correlate with RVGLS.

Conclusions

Both study groups had abnormal myocardial deformation and increased RV volumes. RVGLS in patients was lower than in controls, confirming the effect of increased afterload on myocardial performance.

Evaluation and Management of Right-Sided Heart Failure: A Scientific Statement From the American Heart Association

Background and Purpose:

The diverse causes of right-sided heart failure (RHF) include, among others, primary cardiomyopathies with right ventricular (RV) involvement, RV ischemia and infarction, volume loading caused by cardiac lesions associated with congenital heart disease and valvular pathologies, and pressure loading resulting from pulmonic stenosis or pulmonary hypertension from a variety of causes, including left-sided heart disease. Progressive RV dysfunction in these disease states is associated with increased morbidity and mortality. The purpose of this scientific statement is to provide guidance on the assessment and management of RHF.

Methods:

The writing group used systematic literature reviews, published translational and clinical studies, clinical practice guidelines, and expert opinion/statements to summarize existing evidence and to identify areas of inadequacy requiring future research. The panel reviewed the most relevant adult medical literature excluding routine laboratory tests using MEDLINE, EMBASE, and Web of Science through September 2017. The document is organized and classified according to the American Heart Association to provide specific suggestions, considerations, or reference to contemporary clinical practice recommendations.

Results:

Chronic RHF is associated with decreased exercise tolerance, poor functional capacity, decreased cardiac output and progressive end-organ damage (caused by a combination of end-organ venous congestion and underperfusion), and cachexia resulting from poor absorption of nutrients, as well as a systemic proinflammatory state. It is the principal cause of death in patients with pulmonary arterial hypertension. Similarly, acute RHF is associated with hemodynamic instability and is the primary cause of death in patients presenting with massive pulmonary embolism, RV myocardial infarction, and postcardiotomy shock associated with cardiac surgery. Functional assessment of the right side of the heart can be hindered by its complex geometry. Multiple hemodynamic and biochemical markers are associated with worsening RHF and can serve to guide clinical assessment and therapeutic decision making. Pharmacological and mechanical interventions targeting isolated acute and chronic RHF have not been well investigated. Specific therapies promoting stabilization and recovery of RV function are lacking.

Conclusions:

RHF is a complex syndrome including diverse causes, pathways, and pathological processes. In this scientific statement, we review the causes and epidemiology of RV dysfunction and the pathophysiology of acute and chronic RHF and provide guidance for the management of the associated conditions leading to and caused by RHF.

Ultrasound Segmentation of Rat Hearts Using Convolution Neural Networks

Ultrasound is widely used for diagnosing cardiovascular diseases. However, estimates such as left ventricle volume currently require manual segmentation, which can be time consuming. In addition, cardiac ultrasound is often complicated by imaging artifacts such as shadowing and mirror images, making it difficult for simple intensity-based automated segmentation methods. In this work, we use convolutional neural networks (CNNs) to segment ultrasound images of rat hearts embedded in agar phantoms into four classes: background, myocardium, left ventricle cavity, and right ventricle cavity. We also explore how the inclusion of a single diseased heart changes the results in a small dataset. We found an average overall segmentation accuracy of 70.0% ± 7.3% when combining the healthy and diseased data, compared to 72.4% ± 6.6% for just the healthy hearts. This work suggests that including diseased hearts with healthy hearts in training data could improve segmentation results, while testing a diseased heart with a model trained on healthy hearts can produce accurate segmentation results for some classes but not others. More data are needed in order to improve the accuracy of the CNN based segmentation.

Acute Right Heart Failure

Heart failure is defined as a life-threatening complex clinical syndrome with exacerbation of symptoms signifying decompensation and requires emergent treatment. In its acute state it presents within 24 hours with symptoms such as shortness of breath, volume overload including pulmonary edema, sometimes forward failure and even cardiogenic shock. Two forms of acute heart failure exist: newly diagnosed “de novo” or acutely decompensated chronic heart failure. This chapter summarizes the clinical and prognostic classification of acute right heart failure, epidemiology, diagnostic work-up and the principles behind treatment and management options that focus on preload optimization, afterload reduction and improvement of contractility.

The Dark Side of the Moon: The Right Ventricle

The aim of this review article is to summarize current knowledge of the pathophysiology underlying right ventricular failure (RVF), focusing, in particular, on right ventricular assessment and prognosis. The right ventricle (RV) can tolerate volume overload well, but is not able to sustain pressure overload. Right ventricular hypertrophy (RVH), as a response to increased afterload, can be adaptive or maladaptive. The easiest and most common way to assess the RV is by two-dimensional (2D) trans-thoracic echocardiography measuring surrogate indexes, such as tricuspid annular plane systolic excursion (TAPSE), fractional area change (FAC), and tissue Doppler velocity of the lateral aspect of the tricuspid valvular plane. However, both volumes and function are better estimated by 3D echocardiography and cardiac magnetic resonance (CMR). The prognostic role of the RV in heart failure (HF), pulmonary hypertension (PH), acute myocardial infarction (AMI), and cardiac surgery has been overlooked for many years. However, several recent studies have placed much greater importance on the RV in prognostic assessments. In conclusion, RV dimensions and function should be routinely assessed in cardiovascular disease, as RVF has a significant impact on disease prognosis. In the presence of RVF, different therapeutic approaches, either pharmacological or surgical, may be beneficial.