Switching the Left and the Right Hearts: A Novel Bi-ventricle Mechanical Support Strategy with Spared Native Single-Ventricle

Abstract

Mechanical circulatory support (MCS) is used as a bridge-to-heart transplantation for end-stage failing Fontan patients with single-ventricle (SV) circulation. Donor shortage and complexity of the single-ventricle circulation physiology demands novel circulatory support systems and alternative solutions. An out-of-the-box circulation concept in which the left and right ventricles are switched with each other inspired a novel bi-ventricle MCS configuration for the "failing" Fontan patients. In the proposed configuration, the systemic circulation is maintained by a conventional mechanical ventricle assist device while the venous circulation is delegated to the native SV. This approach spares the SV and puts it to a new use at the right-side providing the most needed venous flow pulsatility. To analyze its feasibility and performance, 8 realistic Fontan circulation scenarios have been studied via a multi-compartmental lumped parameter cardiovascular model (LPM). Model is developed specifically for simulating the SV circulation and validated against pulsatile mock-up flow loop measurements for the ideal (Fontan), failed (VD) and assisted Fontan (PVR-cmcs) scenarios. The proposed surgical configuration maintained the cardiac index (3-3.5 l/min/m 2 ) providing a normal mean systemic arterial pressure. For a failed SV with low ejection fraction (EF=26%), representing a typical systemic failure, proposed configuration introduced a venous/pulmonary pulsatility of ~28 mmHg and a drop of 2 mmHg in central venous pressure (CVP) with acceptable pulmonary artery pressures (17.5 mmHg). In the pulmonary vascular resistance (PVR) failure model, it provided approximately 5 mmHg drop in CVP with venous/pulmonary pulsatility reaching ~22 mmHg. For high PVR failure case with a healthy SV (EF = 44%) pulmonary hypertension is likely to occur, indicating a need for precise functional assessment of the failed-ventricle before it is considered for the proposed arrangement.Comprehensive in vitro and in silico results encourage this concept as an economical alternative to the conventional bi-ventricle MCS pending animal experiments.