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Updated: Jun 5, 2026
A Pipeline to Characterize Structural Heart Defects in the Fetal Mouse
Published on: December 16, 2022
Establishing the anatomic hallmarks of congenitally malformed hearts
R H Anderson1, S Webb, N A Brown
1Robert H. Anderson, Sandra Webb, and Nigel A. Brown are at the Department of Pediatrics, National Heart & Lung Institute, Royal Brompton Hospital, London SW3 6LY, United Kingdom.; the MRC Experimental Embryology, St. George's Hospital Medical School, London, United Kingdom.; Teratology Unit, St. George's Hospital Medical School, London, United Kingdom.
Insights
Precise cardiac morphology is vital for understanding congenital heart malformations. Focusing on hallmark features, rather than presumed developmental faults, offers a clearer approach for diagnosis and research.
Area of Science:
- Developmental Biology
- Cardiology
- Medical Morphology
Background:
- Accurate description of congenital heart malformations is crucial across multiple disciplines, including clinical genetics, epidemiology, surgery, and developmental biology.
- Traditional classification of malformed hearts often relies on inferred developmental faults (e.g., endocardial cushion defects), which can be misleading.
- Distinguishing between lesions with similar presumed origins but distinct morphologies is essential for accurate understanding.
Purpose of the Study:
- To advocate for a shift from classifying malformed hearts based on presumed developmental faults to a precise morphological description.
- To emphasize the identification of 'hallmark' morphology that fundamentally defines a specific cardiac lesion.
- To highlight the importance of detailed morphology for understanding developmental biology and human cardiac malformations.
Main Methods:
- Detailed examination and description of cardiac structures in malformed hearts.
- Comparative analysis of distinct cardiac malformations with potentially shared developmental origins.
- Emphasis on identifying defining morphological features ('hallmarks') of each lesion.
Main Results:
- The study illustrates the potential for misclassification when grouping lesions based solely on inferred developmental mechanisms (e.g., atrioventricular endocardial cushion fusion).
- Distinct morphological entities, such as a cleft mitral valve and atrioventricular canal malformations, despite potential shared origins, exhibit significant anatomical differences.
- A hallmark morphology approach provides a more accurate and less misleading characterization of cardiac lesions.
Conclusions:
- Classifying congenital heart malformations based on precise, observable morphology is superior to relying on presumed developmental faults.
- Identifying the hallmark morphology of a lesion is key to its accurate definition and understanding.
- Precise morphological recognition is critical for advancing the study of cardiac development and identifying comparable human conditions.
Abstract:
A detailed knowledge of the precise morphology of the congenitally malformed heart has never been more important. In fields as diverse as clinical genetic counseling, epidemiology, surgery, and development biology, a proper description of morphology is essential to understand the cause and prevention of cardiac malformations. There has been a tendency in the past to categorize malformed hearts on the basis of putative developmental faults that are deduced from abnormal morphology, for example "endocardial cushion" or "looping" defects. We consider that this is potentially misleading. A better approach is exactly to determine cardiac structure so as to identify the "hallmark" (or "prototype") morphology of a given lesion. The hallmark will constitute those features, among all the changes in a malformed heart, that best define its fundamental character. As an example of the confusion produced by mechanistic extrapolation, consider the cleft in the anterior leaflet of an otherwise normal mitral valve, compared with the space between the leaflets bridging the ventricular septum in hearts with common atrioventricular junctions and deficient atrioventricular septation ("atrioventricular canal malformations"). It is probably correct to presume that both of these entities result from failure of fusion of the atrioventricular endocardial cushions. It is quite inappropriate, in contrast, to group these two lesions together morphologically, given the major anatomical differences seen in the formed hearts (Sigfússon et al. 1995). Therefore it is also important from the stance of developmental biology that the precise morphology of a genetically or chemically induced lesion be recognized if appropriate inferences are to be drawn for consideration of morphogenetic mechanisms and of comparable lesions in humans.
