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Atrioventricular conduction system in hearts with muscular ventricular septal defects in the setting of complete
A Smith1, M G Connell, M Jackson
1Institute of Child Health, University of Liverpool, Royal Liverpool Children's Hospital Alder Hey, England.
Insights
This study compares ventricular septal defects in hearts with complete transposition versus normal connections. A unique type of muscular VSD was found in transposition cases, impacting surgical treatment due to its relation to the conduction system.
Area of Science:
- Cardiovascular Pathology
- Congenital Heart Disease
- Surgical Anatomy
Background:
- Ventricular septal defects (VSDs) are common congenital heart anomalies.
- Complete transposition of the great arteries involves discordant ventriculoarterial connections.
- Understanding VSD morphology is crucial for surgical planning and outcomes.
Purpose of the Study:
- To compare the detailed structure of VSDs in hearts with complete transposition versus concordant connections.
- To identify and characterize unique VSD morphologies in complete transposition.
- To investigate the relationship between VSD location and the atrioventricular conduction axis.
Main Methods:
- Comparative analysis of 90 hearts with complete transposition and 102 hearts with concordant connections.
- Detailed morphological examination of interventricular communications.
- Histologic sectioning to determine the position of the atrioventricular conduction tissue axis.
Main Results:
- A distinct type of muscular VSD was identified in 13% of hearts with complete transposition, absent in concordant hearts.
- These unique VSDs were muscular, subtricuspid, and located on the right side of the septum.
- The atrioventricular conduction axis consistently ran to the surgeon's right margin of these defects, differing from typical inlet VSDs.
Conclusions:
- Hearts with complete transposition exhibit unique muscular VSDs with specific anatomical relationships.
- The atypical position of the conduction axis relative to these VSDs has significant implications for surgical intervention.
- Accurate anatomical characterization of VSDs is essential for optimizing surgical strategies in complex congenital heart disease.
Abstract:
The detailed structure of a ventricular septal defect was compared in 90 hearts with complete transposition (concordant atrioventricular and discordant ventriculoarterial connections) and in 102 hearts with concordant connections at both junctions; the latter group was selected to include only cases with the septums aligned in the normal way. The interventricular communications observed in 13% of the group with complete transposition, which, in our material, had no counterpart in the hearts with concordant segmental connections, were of special interest. These defects, completely surrounded by muscle, were positioned around the midline on the right side of the septum but always lay under or partially under the septal leaflet of the tricuspid valve. The medial papillary muscle group was always to the "left hand margin" of the defect as seen by the surgeon. Because these defects lay within the boundaries set by the septal leaflet of the tricuspid valve, they would conform to the criteria for classification as inlet muscular defects but could equally be described as central or subtricuspid. It is significant that, in all those cases with histologic sectioning, the axis of atrioventricular conduction tissue ran to the surgeon's right hand margin. This position is markedly different from the pattern found in typical defects of the inlet septum, which are completely surrounded by muscle and extend to the posterior wall of the heart. In this more common situation, the conduction axis runs above the left hand margin of the defect. This finding has obvious implications for surgical treatment.