Residual Shunts Following Isolated Surgical Ventricular Septal Defect Closure: Risk Factors and Spontaneous Closure

Although isolated congenital ventricular septal defects (VSD) can be repaired with a high degree of success, residual shunts (RS) are commonplace postoperatively. Small RS are relatively innocuous and tend to spontaneously close with time, despite the emotional burden it poses for the patient and family. A large RS, however, needs ongoing surveillance and may necessitate reintervention. Factors influencing the incidence of RS as well as the likelihood and expected timing of its spontaneous closure are discussed in this study. The patient records and relevant data of 362 consecutive patients undergoing cardiac operation with isolated congenital VSD closure as primary procedure between January 2017 and December 2017 were included in the study. Postoperative transthoracic echocardiograms were performed at hospital discharge, and during follow-up, at 1 month, 3 months, 6 months and 1 year postoperatively. Residual defects were measured under echocardiogram at every follow-up. Factors expected to be associated with RS occurrence and spontaneous closure were included for logistic and Cox regression statistical analysis. There were 113 cases where RS occurred according to the first postoperative echocardiograms that were performed at discharge, of which 80 were confirmed closed during subsequent follow-up, with a median follow-up of 96 days. A cutoff of 1.25 mm for the initial RS was found to be the best predictor of spontaneous closure at 6-month follow-up. Small shunts had higher closure rate than larger ones by a follow-up duration of 300 days, at which the two groups tended to reach a similar spontaneous closure rate. Longer surgical bypass time distinguished small from larger residual shunts measured upon discharge. Following repair of isolated congenital VSDs, the incidence of a residual shunt is high. The majority spontaneously close within 300 days following surgery. Longer bypass time predicted a larger residual shunt upon discharge. Larger than 1.25 mm shunts had lower short-term closure rate but seemed not to differ from smaller shunts beyond 300 days postoperatively.