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The cardiac malformations. Double inlet left ventricle and corrected transposition explained as deviations in the
Insights
Altered development of the interventricular septum may explain cardiac malpositions like double inlet left ventricle and corrected transposition. Minor deviations in the embryonic heart tube
Area of Science:
- Embryology
- Cardiovascular Anatomy
- Developmental Biology
Background:
- Cardiac malpositions, including double inlet left ventricle and corrected transposition, present complex anatomical challenges.
- Understanding the developmental origins of these conditions is crucial for diagnosis and treatment.
Purpose of the Study:
- To test the hypothesis that abnormal interventricular septum development underlies cardiac ventricular malpositions.
- To elucidate the embryologic mechanisms leading to double inlet left ventricle and corrected transposition.
Main Methods:
- Retrospective analysis of autopsy heart specimens from Johns Hopkins Hospital.
- Inclusion criteria: double inlet left ventricle (16 cases) and corrected transposition (9 cases).
- Comparative morphologic examination and developmental pathway analysis.
Main Results:
- Normal ventricular septation arises from a spiral fold in the primary heart tube.
- Double inlet left ventricle may result from an unspiraled ring around the interventricular canal.
- Corrected transposition may stem from a leftward-deviated interventricular sulcus influencing septal positioning and ventricular morphology.
Conclusions:
- Minor deviations in the embryonic interventricular sulcus position can explain double inlet left ventricle and corrected transposition.
- The proposed mechanism accounts for the characteristic morphologic findings in these congenital heart defects.
- This developmental concept offers insights into the pathogenesis of complex cardiac malpositions.
Abstract:
To examine the hypothesis that malpositions of cardiac ventricles could be explained by altered development of the interventricular septum, we studied hearts from the Johns Hopkins Hospital autopsy files with double inlet left ventricle (16 cases) or corrected transposition (nine cases). In double inlet left ventricle (16 cases) or corrected transposition (nine cases). In double inlet ventricle both atrioventricular valves connect normally developed and positioned right and left atria to a posterior morphologic left ventricle. In hearts with corrected transposition the atria are normally positioned and the morphologic right ventricle is on the left and is continuous with the anteriorly positioned aorta. The morphologic left ventricle is on the right, connected to the posteriorly positioned pulmonary trunk. Normal ventricular septation may be understood as arising from the mechanics of a spiral fold in the primary heart tube produced by the left interventricular sulcus. The ventral limb of the spiral induces the muscular interventricular septum while the dorsal limb becomes a component of the crista supraventricularis. We propose that double inlet left ventricle and corrected transposition are the result of minor deviations in the position of the interventricular sulcus on the primary heart tube. Double inlet left ventricle may develop from the formation of a closed unspiraled ring around the interventricular canal. Corrected transposition may result from a left interventricular sulcus whose ventral limb gives rise to a left sided crista supraventricularis, which determines in part the right ventricular morphology of the left sided ventricle. The dorsal limb spirals toward th atrioventricular canal, gives rise to a malpositioned interventricular septum, and displaces the embryonic trabeculated right ventricle to the left. The concept presented accounts for the morphologic findings characteristic of double inlet left ventricle and corrected transposition.