Subaortic Stenosis after Repair of Complete Atrioventricular Septal Defect: Anatomic and Technical Issues

Objective: This report is a review of our institutional experience with subaortic stenosis developing after repair of complete atrioventricular septal defects (CAVSD).

Patients and Methods: Between 1986 and 2012, 383 patients (median age: 2.15 years, range: 0 – 4.7 years) underwent biventricular correction of CAVSD. During a median follow-up of 16.06 years (range: 1 – 25 years), 89 (23.8%) patients underwent first reoperations, 33 (8%) underwent second reoperations, while 20 (5%), 10 (2.6%), 6 (1.6%), and 5 (1.3%) patients underwent third, fourth, fifth, and sixth reoperations, respectively. The most common causes of reoperations are left atrioventricular valve regurgitation, residual ventricular septal defect, subaortic stenosis, and late onset complete heart block.

Results: Nineteen patients (median age: 6.25 years, range: 0 – 23 years) developed subaortic stenosis. They had 26 reinterventions within 6 months 23 years after the initial surgery. Seventeen patients had severe subaortic stenosis (mean pressure gradient of 80 ± 20 mm Hg) to warrant resection of the left ventricular outflow tract obstruction. A spectrum of surgical approaches has been employed and this will be described in detail. Freedom from reoperation is 100, 82.3, 35.3, and 17.6% at 30 days, 1, 5, and 15 years, respectively. Cumulative survival is 100% at 1 year, and 81.3% at 16 years. The other two patients have mild subaortic stenosis (mean pressure gradient: 10 ± 3 mm Hg); hence, there is still no indication for surgery. In this series, the prevalence of subaortic stenosis is 4.9%.

Conclusion: The risk of developing subaortic obstruction after repair of the CAVSD is real and may occur more commonly than previously reported. Anatomical and technical issues during the initial CAVSD correction should be dealt with to reduce the incidence of subaortic stenosis.