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Truncus arteriosus malformation: a developmental arrest at Carnegie stage 14
1Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21287-6901, USA.
Teratology
|January 1, 1996
Summary
Truncus arteriosus malformation results from a delayed or failed development of the embryonic outflow tract, preventing proper septation and valve formation. This cardiac defect is linked to the outflow tract
Area of Science:
- Developmental Biology
- Cardiovascular Science
- Embryology
Background:
- Truncus arteriosus pathogenesis is debated, with theories including conotruncal ridge deficiency or septal absence.
- Previous hypotheses lack comprehensive analysis of early cardiac development in relation to this malformation.
Purpose of the Study:
- To re-examine the pathogenesis of truncus arteriosus malformation.
- To correlate embryonic outflow tract development with observed cardiac morphology in truncus arteriosus.
Main Methods:
- Morphological review of 28 hearts with truncus arteriosus.
- Comparison with cardiogenesis sequences in 351 normal human embryos (Carnegie Embryological Collection).
Main Results:
- All malformed hearts lacked a muscular outflow tract (conal) septum.
- Truncus arteriosus valves frequently had three (20/28) instead of four commissures.
- Fibrous continuity between mitral and truncal valves was common, suggesting some normal development.
Conclusions:
- Truncus arteriosus results from the embryonic outflow tract failing to achieve an elliptical shape by Carnegie stage 14.
- This failure impedes the formation and fusion of cushions necessary for outflow tract and semilunar valve subdivision.
- Delayed acquisition of elliptical configuration is the primary cause of truncus arteriosus malformation.