12. Left Ventricular Outflow Tract Obstruction Following Partial Atrioventricular Septal Defect Repair
A. Tayfun Gurbuz, William M. Novick, Connie R. Pierce, Donald C. Watson
University of Tennessee-Memphis, Le Bonheur Childrens Medical Center
Memphis, Tenn.
Background: Narrowing of the left ventricular outflow tract (LVOT) has been associated with partial atrioventricular (AV) septal defects in about 3 percent of patients. Because of predisposing anatomy, hemodynamically significant obstruction in the subaortic area may appear following repair of ostium primum atrial septal defects.
Methods: From 1984 through 1997, 38 patients underwent surgical correction of partial AV septal defects by patch closure. The mean age at initial repair was 5.8 years (three months-22 years). Twenty-six patients had repair of a left AV valve cleft. Operative reports, echocardiograms and/or cardiac catheterization cine angiograms were reviewed. Clinical and echocardiographic follow-up was performed in 34 patients of 6.2 years (mean 1-13 years).
Results: Eight patients had 11 subsequent operations for hemodynamically significant subaortic obstruction. The mean age at partial AV septal defect repair in these patients was 15 months (3-24 months p<0.001 compared to others). In addition, the left AV valve cleft was repaired in five patients. Follow-up diagnostic work-up was obtained due to exceptional dyspnea and decreased exercise tolerance in three patients, exertion induced chest pain in two patients, and an abnormal echocardiogram in three asymptomatic patients. The mean gradient across LVOT was 81 mm Hg (50-150 mm Hg) at cardiac catheterization. The average time to development of subaortic stenosis was 4.3 years (1-10 years), six or more years in three patients. The mean age at reoperation was seven years. Eight patients underwent subaortic membrane resection. Of these, three required additional operations for recurrent LVOT obstruction.
Conclusions: The incidence of LVOT obstruction after partial AV septal defect repair may not be higher than reported. Patients having AV septal defect repair at an early age are more likely to develop LVOT obstruction. Recurrent cases following subaortic resection point to the progressive nature of the process, therefore, echocardiography should be performed in all patients to uncover subclinical stenosis. Long-term follow-up is essential for diagnosis due to delayed appearance and lack of reliable clinical signs.