Coronary Arterial Abnormalities in Hypoplastic Left Heart Syndrome: Pathologic Characteristics of Archived Specimens

Impact of Atretic Aortic Valve on Systemic Ventricular Function After the Norwood Procedure

BACKGROUND

Aortic atresia (AA) is considered a risk for the Norwood procedure. This study aimed to compare the longitudinal ventricular function (VF) and atrioventricular valve (AVV) regurgitation in patients with AA and aortic stenosis (AS).

METHODS

Using serial echocardiographic images in patients undergoing the neonatal Norwood procedure between 2001 and 2020, systemic VF assessed by ejection fraction and the degree of AVV regurgitation were compared between the patients with AA and AS.

RESULTS

A total of 335 consecutive patients were included, consisting of 273 with hypoplastic left heart syndrome and 62 with its variants. AA was observed in 146 patients (43.6%) and AS in 189 (56.4%). Longitudinal VF and AVV regurgitation were evaluated using a total of 4687 echocardiograms. Preoperatively, VF was better in AA patients than in AS patients (P = .01). After the Norwood procedure, VF was initially (1-30 days) worse in patients with AA than in those with AS (P < .01). However, after that (31 days to stage 2 palliation), it improved in the AA group but remained worse than in the AS group (P < .01). After stage 2 palliation, VF was reduced in the AA group compared to the AS group, especially between 31 to 90 days postoperatively (P < .01). The degree of AVV regurgitation after the Norwood procedure (P < .01) as well as after stage 2 palliation (P < .01), was worse in AA patients, compared with AS patients.

CONCLUSIONS

After the Norwood procedure, patients with AA demonstrated inferior systemic VF as well as worse AVV function throughout the palliation period before Fontan completion.

Identification of Hypoplastic Left Heart Genotypes and Phenotypes; The Window toward Future Cell-Based Therapy: A Narrative Review

Hypoplastic left heart syndrome (HLHS) is a prevalent and lethal type of single ventricle anomaly. During early prenatal evaluations, left heart hypoplasia may be neglected due to its progressive features. It is a heterogeneous congenital heart disease with different phenotypes. Currently, there is no definite treatment for HLHS. This is in part due to its heterogeneous phenotypes that require different management. In addition, hindrances in recognizing the etiologic factors do not allow early preventive or therapeutic procedures. Phenotypic determination is fundamental to identifying the etiologic factors and therapeutic strategies. This review article introduces comprehensive information about different phenotypes and genotypes of HLHS and their novel molecular strategy. Genetic defects and flow-mediated mechanisms are the main known factors of HLHS. Recent studies reported additional data about its nonmendelian genetic origins associated with heterogeneous phenotypes. The genetic defects influence endocardium or cardiomyocyte development to yield early or late valve deformities and myocardial malformations. The new molecular therapeutic methods are essentially based on genetic etiologies. The principal therapeutic purpose is reinforcing the function of the right ventricle in patients with nonfunctional left ventricles. The ultimate desire is to create a biventricular heart in selected cases.

Ventriculocoronary connection with mitral stenosis/aortic stenosis hypoplastic left heart: a case report

Ventriculocoronary connections develop most commonly in children with mitral stenosis/aortic atresia hypoplastic left heart. These connections can lead to myocardial ischaemia and dysfunction. We report a newborn with mitral stenosis/aortic stenosis hypoplastic left heart who endured systemic ventricular injury post-Norwood, secondary to a large ventriculocoronary fistula. He was treated medically and had favourable outcomes following bidirectional Glenn procedure.

Hypoplastic Left Heart Syndrome with Mitral Stenosis and Aortic Atresia-Echocardiographic Findings and Early Outcomes

BACKGROUND

Mitral stenosis/aortic atresia (MS/AA) has been reported as a high-risk variant of hypoplastic left heart syndrome (HLHS), potentially related to ventriculocoronary connections (VCCs) or endocardial fibroelastosis (EFE) and myocardial hypoperfusion. We aimed to identify echocardiographic and clinical factors associated with early death or transplant in this group.

METHODS

Patients with HLHS MS/AA treated at our center between 2000 and 2020 were included. Pre-stage I palliation echocardiograms were reviewed. Certain imaging factors, such as determination of VCC, EFE, and measurement of tricuspid annular plane systolic excursion were measured from retrospective review of preoperative images; others were derived from clinical reports. Groups were compared according to primary outcome of death or transplant prior to stage II palliation.

RESULTS

Of 141 patients included, 39 (27.7%) experienced a primary outcome. Ventriculocoronary connections were identified in 103 (73.0%) patients and EFE in 95 (67.4%) patients. Among imaging variables, smaller ascending aorta size (median, 2.2 [interquartile range (IQR) 1.7-2.8] vs 2.6 [2.2-3.4] mm, P = .01) was associated with primary outcome. There was similar frequency of VCC (74.4% vs 72.5%, P = .83), EFE (59.0% vs 72.5%, P = .19), moderate or greater tricuspid regurgitation (5.1% vs 5.9%, P = 1.00), and similar right ventricular systolic function (indexed tricuspid annular plane systolic excursion 32.5 ± 7.3 vs 31.4 ± 7.2 mm/m2, P = .47) in the primary outcome group compared to other patients. Clinical factors associated with primary outcome included lower birth weight (mean, 2.8 ± SD 0.8 vs 3.3 ± 0.5 kg, P = .0003), gestational age <37 weeks (31.6% vs 4.9%, P < .0001), longer cardiopulmonary bypass time (median, 112 [IQR, 93-162] vs 82 [71-119] minutes, P = .001), longer intensive care unit length of stay (median, 19 [IQR, 10-30] vs 10 [7-15] days, P = .001), and extracorporeal membrane oxygenation following stage I palliation (43.6% vs 8.8%, P < .0001). Presence of VCCs and EFE was not associated with death or transplant after controlling for birth weight and era of stage I palliation.

CONCLUSIONS

In one of the largest reported single-center cohorts of HLHS MS/AA, there were few pre-stage I palliation imaging characteristics associated with primary outcome. Imaging findings evaluated in this study, including the presence of VCC and/or EFE as determined using highly sensitive echocardiogram criteria, should not preclude intervention, although impact on long-term outcomes requires further evaluation.

High-Risk Anatomic Subsets in Hypoplastic Left Heart Syndrome

Despite overall improvements in outcomes for patients with hypoplastic left heart syndrome, there remain anatomic features that can place these patients at higher risk throughout their treatment course. These include severe preoperative obstruction to pulmonary venous return, restrictive atrial septum, coronary fistulae, severe tricuspid regurgitation, smaller ascending aorta diameter (especially if <2 mm), and poor ventricular function. The risk of traditional staged palliation has led to the development of alternative strategies for such patients. To further improve the outcomes, we must continue to diligently examine and study anatomic details in HLHS patients.

Prenatally diagnosed coronary artery abnormalities in hypoplastic left heart syndrome are associated with a higher probability of heart transplantation

OBJECTIVE

Coronary artery abnormalities (CA) occur in patients with hypoplastic left heart syndrome (HLHS) and may be associated with higher mortality and heart transplantation (HT). We aimed to determine whether fetuses with HLHS and prenatal CA have a higher risk of death or HT.

METHODS

We performed a retrospective review of fetal echocardiograms with HLHS from 2011 to 2018. We excluded fetuses with ventricular septal defects, elective termination, death in utero, planned postnatal non-intervention, or absent follow-up data. Presence or absence of CA was determined by review of serial fetal echocardiograms. Survival analysis was used to evaluate the relationship between prenatal CA and death or HT.

RESULTS

Of 86 patients with fetal HLHS, 11 had prenatal diagnosis of CA. Of these, six required HT and five died (one after undergoing HT); only one remains alive without HT. Of those without prenatal CA (n=75), 25 died and 7 underwent HT. Patients with prenatal diagnosis of HLHS and CA had a significantly increased likelihood of death or HT (p-value <0.05).

CONCLUSION

nPrenatal diagnosis of CA in our cohort of patients with HLHS was associated with increased risk of death or HT. These data have significance for prenatal counseling and postnatal management. This article is protected by copyright. All rights reserved.

The Left Ventricular Myocardium in Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS) is a collective term applied to severe congenital cardiac malformations, characterised by a combination of abnormalities mainly affecting the left ventricle, associated valves, and ascending aorta. Although in clinical practice HLHS is usually sub-categorised based on the patency of the mitral and aortic (left-sided) valves, it is also possible to comprehensively categorise HLHS into defined sub-groups based on the left ventricular morphology. Here, we discuss the published human-based studies of the ventricular myocardium in HLHS, evaluating whether the available evidence is in keeping with this ventricular morphology concept. Specifically, we highlight results from histological studies, indicating that the appearance of cardiomyocytes can be different based on the sub-group of HLHS. In addition, we discuss the histological appearances of endocardial fibroelastosis (EFE), which is a common feature of one specific sub-group of HLHS. Lastly, we suggest investigations that should ideally be undertaken using HLHS myocardial tissues at early stages of HLHS development to identify biological pathways and aid the understanding of HLHS aetiology.

Combined Hybrid Procedure and VAD insertion in 9 High-Risk Neonates and Infants with HLHS

BACKGROUND

We report nine high-risk neonates and infants with HLHS stabilized with a Hybrid Approach + VAD insertion (Hybrid+VAD) in preparation for transplantation.

METHODS

Nine patients with HLHS (7 neonates, 2 infants) presented with anatomical and/or physiological features associated with increased risk for conventional univentricular palliation with the Norwood Operation (large coronary sinusoids/fistulas, severe tricuspid regurgitation, cardiogenic shock, restrictive atrial septum). These patients underwent combined VAD insertion (Berlin EXCOR) and stage 1 hybrid palliation (application of bilateral pulmonary bands, stent placement in the PDA, and atrial septectomy if needed). During this same era, at our institution, 41 neonates underwent Norwood Operation, three neonates underwent Hybrid Approach "Stage 1" without VAD, and three HLHS patients were supported with prostaglandin while awaiting transplantation.

RESULTS

At Hybrid+VAD insertion, median age = 20 days (range = 13-143) and median weight = 3.25 kilograms (range = 2.43-4.2). Six patients survive (67%) and three patients died (33%). Five survivors are at home doing well after successful transplantation and one survivor is doing well in the ICU on VAD support awaiting transplantation. Only one of six survivors (16.7%) required intubation more than 10 days after Hybrid+VAD insertion. In eight patients no longer on VAD, median length of VAD support was 119.5 days (range = 56-196 days).

CONCLUSIONS

High-risk patients with HLHS who are suboptimal candidates for Norwood palliation can be successfully stabilized with pulsatile VAD insertion along with hybrid palliation while awaiting cardiac transplantation; these patients may be extubated and optimized for transplantation while on VAD.

Single-Cell RNA Sequencing and Quantitative Proteomics Analysis Elucidate Marker Genes and Molecular Mechanisms in Hypoplastic Left Heart Patients With Heart Failure

Objective

To probe markers and molecular mechanisms of the hypoplastic left heart (HLH) by single-cell RNA sequencing (scRNA-seq) and quantitative proteomics analysis.

Methods

Following data preprocessing, scRNA-seq data of pluripotent stem cell (iPSC)-derived cardiomyocytes from one HLH patient and one control were analyzed by the Seurat package in R. Cell clusters were characterized, which was followed by a pseudotime analysis. Markers in the pseudotime analysis were utilized for functional enrichment analysis. Quantitative proteomics analysis was based on peripheral blood samples from HLH patients without heart failure (HLH-NHF), HLH patients with heart failure (HLH-HF), and healthy controls. Hub genes were identified by the intersection of pseudotime markers and differentially expressed proteins (DE-proteins), which were validated in the GSE77798 dataset, RT-qPCR, and western blot.

Results

Cardiomyocytes derived from iPSCs were clustered into mesenchymal stem cells, myocardium, and fibroblast cells. Pseudotime analysis revealed their differentiation trajectory. Markers in the three pseudotime clusters were significantly associated with distinct biological processes and pathways. Finally, three hub genes (MMP2, B2M, and COL5A1) were identified, which were highly expressed in the left (LV) and right (RV) ventricles of HLH patients compared with controls. Furthermore, higher expression levels were detected in HLH patients with or without HF than in controls.

Conclusion

Our findings elucidate marker genes and molecular mechanisms of HLH, deepening the understanding of the pathogenesis of HLH.