A Cavopulmonary Assist Device for Long-Term Therapy of Fontan Patients

Andreas Escher,Carsten Strauch,Emanuel J Hubmann,Michael Hübler,Dominik Bortis,Bente Thamsen,Marc Mueller,Ulrich Kertzscher,Paul U Thamsen,Johann W Kolar,Daniel Zimpfer,Marcus Granegger

doi:10.1053/j.semtcvs.2021.06.016

Abstract

Treatment of univentricular hearts remains restricted to palliative surgical corrections (Fontan pathway). The established Fontan circulation lacks a subpulmonary pressure source and is commonly accompanied by progressively declining hemodynamics. A novel cavopulmonary assist device (CPAD) may hold the potential for improved therapeutic management of Fontan patients by chronic restoration of biventricular equivalency. This study aimed at translating clinical objectives toward a functional CPAD with preclinical proof regarding hydraulic performance, hemocompatibility and electric power consumption. A prototype composed of hemocompatible titanium components, ceramic bearings, electric motors, and corresponding drive unit was manufactured for preclinical benchtop analysis: hydraulic performance in general and hemocompatibility characteristics in particular were analyzed in-silico (computational fluid dynamics) and validated in-vitro. The CPAD's power consumption was recorded across the entire operational range. The CPAD delivered pressure step-ups across a comprehensive operational range (0-10 L/min, 0-50 mm Hg) with electric power consumption below 1.5 W within the main operating range. In-vitro hemolysis experiments (N=3) indicated a normalized index of hemolysis of 3.8 ± 1.6 mg/100 L during design point operation (2500 rpm, 4 L/min). Preclinical investigations revealed the CPAD's potential for low traumatic and thrombogenic support of a heterogeneous Fontan population (pediatric and adult) with potentially accompanying secondary disorders (e.g., elevated pulmonary vascular resistance or systemic ventricular insufficiency) at distinct physical activities. The low power consumption implied adequate settings for a small, fully implantable system with transcutaneous energy transfer. The successful preclinical proof provides the rationale for acute and chronic in-vivo trials aiming at the confirmation of laboratory findings and verification of hemodynamic benefit.

Highlights

Univentricular hearts (UVHs) account for approximately 10% of all congenital heart defects.[1]
Within an interdisciplinary initiative to meet the medical need for a durable Mechanical circulatory support (MCS) option accessible to an inclusive Fontan population we recently introduced a cavopulmonary assist device (CPAD) designed to substitute the missing subpulmonary ventricle.[22]
In-Silico Hemocompatibility Properties computational fluid dynamics (CFD) data showed the CPAD to operate at hydraulic efficiencies (Supplementary Section 4) above 30% across a broad range (Q = 2À8 L/min)

Summary

Introduction

Univentricular hearts (UVHs) account for approximately 10% of all congenital heart defects.[1] The majority of patients with UVH undergo a Fontan type palliation with total cavopulmonary connection (TCPC).[2] Given the absence of a subpulmonary ventricle after TCPC completion, pulmonary perfusion is driven by elevated central venous pressures. This is associated with several long-term complications directly related to chronic venous congestion including lymphatic dysfunction, reduced cardiac output and liver fibrosis.3À5 These complications result in a failing Fontan circulation[6,7] that presents a primary source of mortality in patients with UVH. The living Fontan population is predicted to double within the 20 years,[9] underpinning the medical need for alternative long-term treatment strategies

Objectives

Methods

Results

Conclusion