Tetralogy of Fallot: nosological, morphological, and morphogenetic considerations
Related Experiment Video
Updated: May 4, 2026
Morphological and Functional Assessment of the Right Ventricle Using 3D Echocardiography
Published on: October 28, 2020
Robert H Anderson1, Diane E Spicer2, Jorge M Giroud3
11 Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
Insights
This study revisits Fallot
Area of Science:
- Cardiovascular Research
- Developmental Biology
- Medical History
Background:
- Tetralogy of Fallot, known as "la maladie bleu", was first described by Fallot 125 years ago.
- Fallot identified key morphological features: interventricular communication, biventricular aorta, subpulmonary stenosis, and right ventricular hypertrophy.
- Initial descriptions included variations such as double-outlet right ventricle.
Purpose of the Study:
- To re-examine Fallot's original descriptions in light of current understanding and controversies.
- To clarify the relationship between the ventricular septal defect and the interventricular communication in Tetralogy of Fallot.
- To explore the morphological variations in Tetralogy of Fallot using developmental mouse models.
Main Methods:
- Comparative analysis of Fallot's historical descriptions with contemporary findings.
- Examination of cardiac morphology in developing mouse models.
- Histological and potentially molecular investigations of cardiac development.
Main Results:
- Significant variations exist in the borders of the ventricular septal defect.
- The ventricular septal defect is not always congruent with the geometric plane separating ventricular cavities.
- The interventricular communication may differ from the ventricular septal defect.
Conclusions:
- Fallot's initial observations remain relevant, highlighting complex cardiac morphology.
- A precise distinction between the ventricular septal defect and interventricular communication is crucial.
- Further molecular studies are needed to elucidate the developmental mechanisms of Tetralogy of Fallot.
Abstract:
It is timely, in the 125th anniversary of the initial description by Fallot of the hearts most frequently seen in patients presenting with "la maladie bleu", that we revisit his descriptions, and discuss his findings in the light of ongoing controversies. Fallot described three hearts in his initial publication, and pointed to the same tetralogy of morphological features that we recognise today, namely, an interventricular communication, biventricular connection of the aorta, subpulmonary stenosis, and right ventricular hypertrophy. In one of the hearts, he noted that the aorta arose exclusively from the right ventricle. In other words, one of his initial cases exhibited double-outlet right ventricle. When we now compare findings in hearts with the features of the tetralogy, we can observe significant variations in the nature of the borders of the plane of deficient ventricular septation when viewed from the aspect of the right ventricle. We also find that this plane, usually described as the ventricular septal defect, is not the same as the geometric plane separating the cavities of the right and left ventricles. This means that the latter plane, the interventricular communication, is not necessarily the same as the ventricular septal defect. We are now able to provide further insights into these features by examining hearts prepared from developing mice. Additional molecular investigations will be required, however, to uncover the mechanisms responsible for producing the morphological changes underscoring tetralogy of Fallot.
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