Spontaneous closure of small residual ventricular septal defects after surgical repair.

BACKGROUND: Residual shunts may be detected by intraoperative or postoperative echocardiography after surgical closure of a ventricular septal defect (VSD). The hemodynamic relevance and rate of late closure are unknown.
METHODS: Between 1994 and 2005, 198 consecutive patients underwent surgical correction of an isolated VSD (n = 100), tetralogy of Fallot (n = 52) or atrioventricular septal defect (n = 46). Intraoperative transesophageal echocardiography (TEE) was routine, and postoperative transthoracic echocardiography was performed in the intensive care unit, at hospital discharge, and during follow-up. Residual defects were graded as absent, between 1 and 2 mm, or greater than 2 mm.
RESULTS: Shunt-related discrepancy was observed between intraoperative TEE and intensive care unit transthoracic echocardiographic findings; significantly so after Fallot repair (p < 0.0001). After discharge, 83% of all residual defects less than 2 mm closed. Of nine residual defects greater than 2 mm, only three closed after a median follow-up of 3.1 years. In patients with residual shunts, they were hemodynamically insignificant, required no medication, and no endocarditis was noted. At last follow-up, there was no significant difference between the percentage of residual shunts among the three groups (p = 0.135).
CONCLUSIONS: Postsurgical residual VSDs less than 2 mm closed spontaneously in the majority within a year. Defects greater than 2 mm are unlikely to close spontaneously. Residual shunts after atrioventricular septal defect repair almost always close, whereas one third will remain open after Fallot or isolated VSD repair. At midterm follow-up, residual shunts remained hemodynamically and clinically irrelevant. Revision of a residual defect greater than 2 mm on cardiopulmonary bypass at initial repair, guided by TEE, may spare late redo surgery and lifelong antibiotic prophylaxis.