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Straddling right atrioventricular valves in atrioventricular discordance
Insights
This study details four complex congenital heart cases with a straddling atrioventricular valve. Findings reveal unique conduction system patterns in atrioventricular discordance, impacting surgical planning.
Area of Science:
- Cardiology
- Congenital Heart Disease
- Cardiac Morphology
Background:
- Congenital heart disease presents diverse anatomical challenges.
- Understanding atrioventricular valve abnormalities is crucial for diagnosis and treatment.
Observation:
- Four hearts exhibited a right atrioventricular valve straddling the interventricular septum.
- The valve committed 20-45% of flow to the morphologically right ventricle.
- Ventriculoarterial connections varied, including discordant, double outlet, and single outlet with pulmonary atresia.
Findings:
- Pulmonary stenosis or atresia was noted in all cases.
- Conduction system analysis revealed an anterior atrioventricular node and penetrating bundle, with lateral connections.
- A unique conduction tissue sling was observed in one case.
Implications:
- These anatomical variations necessitate tailored surgical approaches.
- Detailed understanding of conduction pathways is vital for managing complex congenital heart defects.
- Further research can refine diagnostic and therapeutic strategies for these rare conditions.
Abstract:
Four hearts are described in which the right atrioventricular valve, draining a morphologically right atrium, straddled and overrode a septum between a right-sided chamber of left ventricular morphology and a left-sided chamber of right ventricular morphology. The degree of override varied between the straddling valve and was committed by 20-45% to the morphologically right ventricle. The ventriculoarterial connections in the hearts were discordant in one, double outlet from the morphologically right ventricle in two and single outlet via an aorta from the morphologically right ventricle with pulmonary atresia in the other. The straddling valve in one of the cases with double outlet had a dual orifice. Pulmonary stenosis was present in three cases, and pulmonary atresia in the fourth. Study of the conduction system in three of the hearts revealed subtle but important differences from the pattern expected in atrioventricular discordance. Each case had an anterior atrioventricular node and penetrating bundle, but the connection thus formed was more lateral than usual, and in the case with ventriculoarterial discordance, the nonbranching bundle was unrelated to the pulmonary outflow tract. A sling of conduction tissue between the anterior node and the regular node was found in the case with single outlet and pulmonary atresia.