Evaluation of Ventricular Septal Defect Repair Using Intraoperative Transesophageal Echocardiography: Frequency and Significance of Residual Defects in Infants and Children

Abstract

Intraoperative transesophageal echocardiography (IOTEE) is commonly used to assess for residual defect and the need to return to bypass after repair of ventricular septal defect (VSD). The frequency and significance of residual septal defects as noted on IOTEE has not been well defined. We evaluated the frequency of residual VSD via IOTEE and the relationship between size of a residual VSD and rate of reoperation. In addition, we looked at the relationship between the presence of a residual VSD via IOTEE and the presence of residual VSD at follow-up transthoracic echocardiography (TTE). Residual VSD was measured via the largest width of the Doppler color jet diameter originating at the left ventricular septal surface. Of the 294 patients evaluated with IOTEE after VSD repair, one-third had a residual defect by IOTEE Doppler color flow mapping. Two-thirds of these defects closed spontaneously on TTE by the time of hospital discharge. There was no difference in frequency of residual VSD between simple (VSD closure alone, n = 90) and complex (VSD with associated lesions, n = 204) repair. Return to bypass with immediate reoperation was undertaken in nine patients, all of whom had significant shunt via oximetry (Qp/Qs > 1.5:1.0). All had residual VSD color jet diameters > 3 mm. Seven patients had residual color jet equal to 3 mm; however, hemodynamic studies did not reveal a significant shunt and none of these had reoperation. Seven patients with no VSD or < 3 mm residual VSD via had late reoperation to close residual VSD at 4 days to 5 months after initial operation. These were due to patch dehiscence or development of an "intramural" VSD in patients with conotruncal anomaly. A residual defect on IOTEE color Doppler measuring > or = 4 mm predicts the need for immediate reoperation, while a 3 mm defect may be significant and requires additional intraoperative hemodynamic evaluation. The majority of small defects noted on IOTEE are not present at discharge TTE. Patients with conotruncal defect repair should be followed closely for development of late significant "intramural" defects.

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

“…This is comparable to the rates observed after VSD closure for isolated simple VSD in 2 other studies with large sample volumes, namely 25 and 33% in the reports by Dodge-Khatami et al [23] and Yang et al [24], respectively. Our incidence of 12% at predischarge was far more favorable than the incidences of 35 and 34% in those reports, and our 0% incidences at Qp/Qs ratio of the pulmonary blood flow to the systemic blood flow, Pp/Ps ratio of the pulmonary pressure to the systemic pressure, pV PA peak velocity of PA flow, pV ratio ratio of pV PA to pV LVOT follow-up also compared favorably with the 9% incidence at the median follow-up of 3.1 years in the former report by Dodge-Khatami et al…”

“…Yang et al concluded that defects on CDI measuring more than 4 mm in diameter predicted the need for immediate reoperation, while 3 mm defects were potentially significant and required additional intraoperative hemodynamic evaluation [24]. Though our measurements of the sizes of the jets were inexact, our method of grading the leakage based on subjective judgment by anesthesiologists experienced with TEE was certainly stricter than the actual measurements in the other two reports.…”

Accuracy of the transpulmonary ultrasound dilution method for detection of small anatomic shunts

“…This phenomenon has been investigated predominantly following corrective cardiac surgery for congenital heart disease, where the incidence of echocardiographically diagnosed residual shunt may be in the range of 33-38 % for certain lesions [1][2][3][4]. However, the accuracy of shunt identification may vary according to the timing of imaging (relative to surgery), and the echocardiographic modality used [3].…”

Common Atrioventricular Canal Defects

“…In general, a residual defect measuring less than 3 mm at its greatest diameter will not require surgical reintervention, whereas defects greater than 4 mm will require immediate reoperation. In borderline cases or in very small infants, intraoperative hemodynamic assessment of the residual shunt -by measuring the ratio of pulmonary blood flow to systemic blood flow (Qp:Qs) via oxygen saturation measurements -can help in the decision-making process [25].…”

“…Residual ASDs are unusual but can occur. Small residual VSDs are common [25,30]. Color Doppler is a very sensitive technique to assess for residual shunts.…”