Can intraoperative TEE correctly measure residual shunt after surgical repair of ventricular septal defects?

No groups have yet succeeded in identifying the need for re-repair of residual shunt after surgical repair of ventricular septal defect (VSD) based on quantitative evaluation of the ratio of the pulmonary blood flow to the systemic blood flow (Qp/Qs) by transesophageal echocardiography (TEE). Hence, we studied the accuracy of Qp/Qs as estimated by intraoperative TEE.

Twenty-six patients undergoing VSD closure were studied. After separation from the cardiopulmonary bypass, the presence and severity of residual leakage was evaluated by color Doppler image, and the Qp/Qs (TEE-derived Qp/Qs) was calculated by measuring the vessel diameter and the velocity-time integral of the flow profiles in the main pulmonary artery and left ventricular outflow tract. Transthoracic echocardiography (TTE) was performed at pre-discharge and at 6-12 months after the correction to confirm the presence and severity of residual leakage.

TEE detected only minor leakage, with no indication for re-repair, in 8 of the 26 patients. Nevertheless, TEE-derived Qp/Qs varied from 0.57 to 2.07 and were incorrect in 17 patients (65.4%). This meant that when TEE-derived Qp/Qs was outside the acceptable range, the patient was judged not to be in need of re-repair. TTE at pre-discharge confirmed trivial leakage in 3 patients in whom TEE had also identified similar leakages. These leakages were not observed at the follow-up TTE.

TEE-derived Qp/Qs lacks the accuracy required to play a crucial role in quantitatively measuring the severity of residual shunt, while two-dimensional TEE can reliably detect residual leakage after VSD closure and lead to optimal judgment on the need for re-repair.