Intramural Ventricular Septal Defects After Conotruncal Anomaly Repair
What is the prevalence of residual intramural ventricular septal defects (VSDs) and their impact on postoperative course after repair of conotruncal anomalies?
A retrospective review was performed at a single center. Patients <18 years of age who underwent biventricular repair of a conotruncal anomaly between January 1, 2006 and June 30, 2013 were included. Transthoracic echocardiograms were reviewed for residual intramural or nonintramural VSDs. The primary outcome was a composite endpoint of mortality, need for extracorporeal membrane oxygenation, and subsequent catheter or surgical VSD closure.
A total of 442 patients with conotruncal anomalies underwent surgery during the study period. A majority (72%) of patients underwent repair of tetralogy of Fallot. Additional lesions included D-transposition of the great arteries (D-TGA) with VSD (10%), truncus arteriosus (9%), double outlet right ventricle (5%), truncus arteriosus (4%), and other (5%). A residual VSD was present in 58% (256 of the 442 subjects). The vast majority (90%) of residual VSDs were small, measuring <2 mm. Out of the 442 subjects, 49 (11%) had intramural VSDs and 207 (47%) had nonintramural VSDs. Patients with intramural VSDs were more likely to reach the primary composite endpoint (death, extracorporeal membrane oxygenation, or need for reintervention) than those with nonintramural VSDs or no residual VSD (14/49 [29%] vs. 15/207 [7%] vs. 6/186 [3%], p < 0.0001). These associations remained significant after adjusting for known risk factors for poor outcomes, including residual VSD size and operative complexity.
As intramural VSDs are associated with postoperative morbidity and mortality, it is important that they be recognized in the postoperative period.
Intramural VSDs, which are interventricular communications through right ventricular free wall trabeculations, may occur after surgical repair of conotruncal anomalies. The rate of residual VSDs appeared relatively high at 58%, although most (90%) defects were <2 mm, and therefore not hemodynamically significant. The role of intraoperative transesophageal echocardiography (TEE) at the study institution was not discussed. It is likely, however, that intramural VSDs may increase in size in the early postoperative period and be underappreciated by intraoperative TEE. The mechanism of increased morbidity and mortality with intramural VSDs is not known with certainty, but may be due to their larger size and increased hemodynamic significance in the early postoperative period.
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