Abstract

Background: Intraoperative assessment of the compliance of the pulmonary vascular bed has been described for patients undergoing either univentricular or biventricular repair of congenital heart defects. We have recently based the decision-making for ventricular septal defect (VSD) closure in tetralogy of Fallot (TOF) with or without pulmonary atresia (PA) and severe abnormalities of the pulmonary arterial tree on the mean pulmonary artery pressure (mPAP) changes during an intraoperative flow-study, according to Reddy M. et al.

Patients and Methods: Between October 1996 and October 1997, 9 patients with TOF, PA and major aortopulmonary collateral arteries and 1 patient with TOF and extremely hypoplastic pulmonary arteries (age: mean ± SD = 66 ± 46 months) underwent primary (n = 7) or secondary (n = 2) one-stage unifocalization or patch-plasty of central pulmonary arteries (n = 1) associated to homograft-reconstruction of the outflow tract of the right ventricle (RV). In all cases the decision whether to close the VSD or not was reached intraoperatively on the base of a flow-study, performed by challenging the pulmonary vascular bed with a blood flow corresponding to a predicted cardiac index of 2.5 L/min/m². The maximum mPAP elevation during flow-study accepted for VSD closure was 30 mmHg.

Results: In 9 cases the mPAP elevation during flow-study remained <=30 mmHg, leading to VSD closure, whereas in 1 case it exceeded 30 mmHg and the VSD was left open. The decision-making for VSD management was successful in 9 cases (closed, n = 8; open, n = 1). In those 8 patients who underwent VSD closure the mPAP detected at flow-study compared favourably with the one measured early (48 hrs) postoperatively [-4% (95% CI: -20/11%)] and at control (11 ± 3 months p.o.) cardiac catheterization [-20% (95% CI: -43/4%)]. Furthermore, early postoperative cardiac catheterization (48 hrs p.o.) of patient with the VSD left open showed a Qp:Qs ratio comparable to the one calculated intraoperatively (0.75:1). In the last, unsuccessful, case the VSD had to be reopened in spite of a reassuring flow-study (mPAP = 29 mmHg), due to hypersystemic RV pressure. This patient eventually died. Post-mortem examination showed diffuse pulmonary vascular obstructive disease.

Conclusion: The high accuracy of the intraoperative pulmonary flow-study [90% (95% CI: 61--99%)] may lead to optimal decision-making for VSD management in patients with complex TOF.