Background.It is desirable to repair but not replace the aortic valve in patients with ventricular septal defect and acquired aortic regurgitation.Precise definition of the valvar pathology with monitoring of its repair perioperatively would enhance the surgical management of this condition.Methods.Fourteen consecutive patients (age, 10.6 + 6 years; weight, 29.7 + 5.7 kg) who underwent repair of ventricular septal defect with aortic regurgitation were studied by intraoperative transesophageal echocardiography.The severity of prolapse of each of the individual aortic cusps and its adjacent sinus was assessed and the valvar regurgitation quantified by Doppler-derived regurgitant indices.The echocardiographic and surgical findings were correlated and the preoperative and postoperative echocardiographic data were compared to assess the effectiveness of operation.Results.Eight subarterial and six perimembranous defects were located accurately and their sizes (11.8 +-.3.0 mm) correlated well (r = 0.80) with the surgical measurements.Transesophageal echocardiography detected prolapse of the aortic valve and its sinus in all 14 patients.The severity of prolapse was severe in 10, moderate in 4, and mild in 5 leaflets.On the basis of these findings, together with the Doppler-derived mean regurgitant indices, exploration of the valve and valvuloplasty were executed appropriately in 12 of 14 patients.In all 14 patients, transesophageal echocardiography after bypass revealed no further cuspal prolapse and significant reduction of the mean regurgitant index (0.55 +-0.23 to 0.17 -0.15, p < 0.0001).Residual ventricular septal defect was detected in 5 patients and the only patient with significant shunting who required reexploration was identified correctly.Conclusions.Intraoperative transesophageal echocardiography can assess effectively the surgical repair of ventricular septal defect with aortic regurgitation and provide information that directs and alters surgical plans to the benefit of patients.