Left-sided obstructive lesions in atrioventricular septal defects: an anatomic study

Area of Science:

• Cardiology
• Congenital Heart Disease
• Pediatric Cardiology

Background:

• Atrioventricular septal defects (ASDs) are complex congenital heart anomalies.
• Obstructions within the heart's systemic flow can arise from various anatomical factors in ASDs.
• Understanding these obstructions is vital for effective surgical management.

Purpose of the Study:

• To analyze actual and potential obstructive factors in the systemic circulation of hearts with atrioventricular septal defects.
• To identify the prevalence and specific causes of inlet and outflow tract obstructions in ASDs.
• To inform surgical strategies by highlighting the significance of potential obstructive lesions.

Main Methods:

• Examination of 114 specimens with atrioventricular septal defects, including those with common and separate atrioventricular orifices.
• Detailed analysis of anatomical features contributing to both actual and potential obstructions.
• Categorization of obstructions based on location (inlet vs. outflow tract) and etiology.

Main Results:

• Potential inlet obstruction was frequently linked to the atrioventricular valve (70% due to deformed leaflets, 17.5% tethering, 8% incomplete cleft).
• Potential left ventricular outflow tract obstruction was observed in 70% of cases, primarily due to abnormal papillary muscle position or hypoplasia.
• Actual obstructions were present in 29% of cases, with inlet obstructions (22%) more common than outlet obstructions (7%).

Conclusions:

• While actual anatomical obstruction occurs in a minority of ASD cases (29%), potential obstructive factors are prevalent.
• Atrioventricular valve abnormalities are a significant source of potential inlet obstruction.
• Surgical repair of atrioventricular septal defects must account for potential, not just actual, obstructions for optimal outcomes.