Biventricular repair with atrial fenestration adds little advantage to the postoperative haemodynamics in borderline candidates compared to the one and a half ventricle repair

Abstract

Purpose: In patients with hypoplastic right ventricle (RV), atrial fenestration (AF) has recently become an option to the conventional biventricular repair (BVR). However, it remains unclear whether BVR with AF adds several advantages to the postoperative haemodynamics compared to the other alternative, the one and a half ventricle repair (1.5VR). To clarify this, we performed a theoretical analysis using computational models. Methods: Computational models of BVR, BVR with small AF (SF-BVR) and large AF (LF-BVR), 1.5VR and Fontan operation were developed with time-varying elastance chamber model and the modified 3-element Windkessel vascular model. While mean systemic arterial pressure was maintained by adjusting stressed blood volume, we varied RV stiffness constant, an index of RV diastolic function, to simulate various degree of hypoplastic RV, and calculated cardiac index, right atrial pressure (RAP) and arterial oxygen saturation for each RV stiffness constant. Results: SF-BVR, LF-BVR and 1.5VR decreased RAP, and increased cardiac index in the borderline candidates. In the borderline candidates with milder RV hypoplasia, 1.5VR increased cardiac index more than BVR with AF. In the borderline candidates with severer RV hypoplasia, LF-BVR delivered the largest cardiac index. However, LF-BVR decreased arterial oxygen saturation below 90% in these candidates. Cardiac index & Oxygen saturation Conclusions: In the borderline candidates with milder RV hypoplasia, AF added little advantage to the postoperative haemodynamics compared to the 1.5VR. Although LF-BVR improves cardiac index in the borderline candidates with severer RV hypoplasia, significant desaturation may prevent the use of AF.