Related Experiment Video
Updated: Jan 28, 2026
Robotic-assisted Left Pneumonectomy For Vanishing Lung Syndrome
Published on: January 23, 2026
Hypoplastic Left Heart Syndrome: A New Paradigm for an Old Disease?
Paul Grossfeld1, Shuyi Nie2, Lizhu Lin3
1Division of Cardiology, Department of Pediatrics, UCSD School of Medicine, La Jolla, CA 92093, USA. pgrossfeld@ucsd.edu.
Insights
Hypoplastic left heart syndrome (HLHS) may stem from cardiomyocyte hyperplasia, not just reduced flow. This suggests HLHS could be a neonatal cardiomyopathy, offering new insights into congenital heart defects.
Area of Science:
- Developmental Biology
- Cardiology
- Genetics
Background:
- Hypoplastic left heart syndrome (HLHS) is a severe congenital heart defect, causing significant infant mortality.
- The etiology of HLHS is multifactorial, with a known genetic cause in only a minority of cases.
- Existing theories on HLHS mechanisms, such as decreased ventricular flow, are debated due to disease variability and lack of accurate animal models.
Purpose of the Study:
- To review evidence suggesting cardiomyocyte hyperplasia as a primary cause of left ventricular hypoplasia in a subset of HLHS cases.
- To explore the role of the endocardium in HLHS development.
- To reframe HLHS as a potential neonatal cardiomyopathy.
Main Methods:
- Literature review of existing research on HLHS.
- Analysis of evidence supporting primary ventricular development defects.
- Discussion of the role of cardiomyocyte proliferation and endocardial function.
Main Results:
- Growing evidence indicates that left ventricular hypoplasia in some HLHS cases results from cardiomyocyte hyperplasia.
- This finding challenges the traditional view of decreased flow as the sole cause.
- The endocardium's role in ventricular development and its potential link to impaired flow is highlighted.
Conclusions:
- HLHS may represent a neonatal form of cardiomyopathy in certain patients, characterized by cardiomyocyte hyperplasia.
- Understanding the primary defect in ventricular development, including endocardial contributions, is crucial for elucidating HLHS pathogenesis.
- This perspective may offer new avenues for research and therapeutic strategies for HLHS.
Abstract:
Hypoplastic left heart syndrome occurs in up to 3% of all infants born with congenital heart disease and is a leading cause of death in this population. Although there is strong evidence for a genetic component, a specific genetic cause is only known in a small subset of patients, consistent with a multifactorial etiology for the syndrome. There is controversy surrounding the mechanisms underlying the syndrome, which is likely due, in part, to the phenotypic variability of the disease. The most commonly held view is that the "decreased" growth of the left ventricle is due to a decreased flow during a critical period of ventricular development. Research has also been hindered by what has been, up until now, a lack of genetically engineered animal models that faithfully reproduce the human disease. There is a growing body of evidence, nonetheless, indicating that the hypoplasia of the left ventricle is due to a primary defect in ventricular development. In this review, we discuss the evidence demonstrating that, at least for a subset of cases, the chamber hypoplasia is the consequence of hyperplasia of the contained cardiomyocytes. In this regard, hypoplastic left heart syndrome could be viewed as a neonatal form of cardiomyopathy. We also discuss the role of the endocardium in the development of the ventricular hypoplasia, which may provide a mechanistic basis for how impaired flow to the developing ventricle leads to the anatomical changes seen in the syndrome.
Related Concept Videos
01:24Cardiac Catheterization III: Left Heart Catheterization
01:23Rheumatic Heart Disease I: Introduction
01:17Ischemic Heart Disease: Overview
Atherosclerosis, the primary malefactor, orchestrates this dangerous condition. It manifests as the accumulation of fatty deposits, akin to insidious plaques, within arterial walls. As time elapses, these plaques metamorphose, hardening and...
01:21Rheumatic Heart Disease III: Medical Management
01:27Anatomy of the Heart
01:20Rheumatic Heart Disease IV: Nursing Management