Controlling the flow balance: In vitro characterization of a pulsatile total artificial heart in preload and afterload sensitivity

Abstract

The objective of this study is to identify the preload and afterload sensitivity of the ReinHeart TAH 2.0. For adequate left-right flow balance, the concept of a reduced right stroke volume (by about 10%) and active adaption of the right diastole duration are evaluated concerning the controllability of the flow balance. This study used an active mock circulation loop to test a wide range of preload and afterload conditions.Preload sensitivity was tested at atrial pressures (APs) between 4 and 20 mm Hg. Left afterload was varied in a range of 60-140 mm Hg mean aortic pressure (MAP), right afterload was simulated between 15 and 40 mm Hg. Four scenarios were developed to verify that the flow difference fully covers the defined target range of 0-1.5 L/min. Although a positive correlation between inlet pressure and flow is identified for the right pump chamber, the left pump chamber already fills completely at an inlet pressure of 8-10 mm Hg. With increasing afterload, both the left and right flow decrease.A positive flow balance (left flow exceeds right flow) is achieved over the full range of tested afterloads. At high APs, the flow difference is limited to a maximum of 0.7 L/min. The controllability of flow balance was successfully evaluated in four scenarios, revealing that a positive flow difference can be achieved over the full range of MAPs. Under physiological test conditions, the linear relationship between flow and heart rate was confirmed, ensuring good controllability of the TAH.

Balancing the ventricular outputs of pulsatile total artificial hearts

“…It is filled with gas and capable of reducing its volume to compensate for volume differences (Figure 1C). We identified the following TAHs in this category: Baylor TAH (Baylor College of Medicine, Houston, TX, USA), 22 Penn State TAH (Pennsylvania State University, Hershey, Pennsylvania, USA), 23 MagScrew TAH (Cleveland Clinic, Cleveland, OH, USA), 24 Nimbus TAH (Cleveland Clinic), 25 and ReinHeart TAH (Helmholtz Institute, Aachen, Germany) 26 . These TAHs are actuated by an alternating pusher plate placed in between both ventricles.…”

“…We found that the mean preload sensitivity for mechanically actuated TAHs in this category was highest for TAHs that are regulated by a left master alternate control system, mean 0.397 (Baylor TAH, 22 Penn State, 23 MagScrew, 24 and Nimbus TAH 25 ) (Figure 2C and Table 1). In contrast, the passive preload‐regulated ReinHeart TAH 26 and Softheart 27 exhibit poorer preload sensitivity, mean 0.039 (Table 1). This implies that the mechanically actuated TAHs in this category benefit from active preload regulation.…”

Detection of physiological control inputs preload and afterload from intrinsic pump parameters in total artificial heart

“…The MCL system that we used has been previously described. The hydraulic hardware components and a software computer model are described in the study by Cuenca et al 16 A graphic image of the MLC components and their function is presented and further described in the study by Hildebrand et al 17 Briefly, the hydraulic mock circulation loop can simulate both lung circulation and systemic circulation. Each of these parts consists of an electrical adjustable arterial compliance chamber, an electrical proportional valve simulating vascular resistance, and passive venous compliance.…”

Computational Modeling of the Penn State Fontan Circulation Assist Device

“…3 Although the most effective treatment is heart transplantation, the limited number of donor organs available highlights the need for the development of a mechanical circulatory assist device to serve as either a bridgeto-transplantation or as a permanent right heart replacement. 3 Several groups have investigated the potential of commercial blood pumps for failing Fontan patients in mock flow loops, [4][5][6] animal Fontan models, [7][8][9] and failing Fontan patients as a bridgeto-transplant. 10,11 Other groups are developing new devices specific to the needs of failing Fontan patients to help reduce load on the single ventricle and improve pulmonary blood flow.…”

“…Several groups have investigated the potential of commercial blood pumps for failing Fontan patients in mock flow loops, 4–6 animal Fontan models, 7–9 and failing Fontan patients as a bridge-to-transplant. 10,11 Other groups are developing new devices specific to the needs of failing Fontan patients to help reduce load on the single ventricle and improve pulmonary blood flow.…”