Simulation of Ventricular, Cavo‐Pulmonary, and Biventricular Ventricular Assist Devices in Failing Fontan

Abstract

Considering the lack of donors, ventricular assist devices (VADs) could be an alternative to heart transplantation for failing Fontan patients, in spite of the lack of experience and the complex anatomy and physiopathology of these patients. Considering the high number of variables that play an important role such as type of Fontan failure, type of VAD connection, and setting (right VAD [RVAD], left VAD [LVAD], or biventricular VAD [BIVAD]), a numerical model could be useful to support clinical decisions. The aim of this article is to develop and test a lumped parameter model of the cardiovascular system simulating and comparing the VAD effects on failing Fontan. Hemodynamic and echocardiographic data of 10 Fontan patients were used to simulate the baseline patients' condition using a dedicated lumped parameter model. Starting from the simulated baseline and for each patient, a systolic dysfunction, a diastolic dysfunction, and an increment of the pulmonary vascular resistance were simulated. Then, for each patient and for each pathology, the RVAD, LVAD, and BIVAD implantations were simulated. The model can reproduce patients' baseline well. In the case of systolic dysfunction, the LVAD unloads the single ventricle and increases the cardiac output (CO) (35%) and the arterial systemic pressure (Pas) (25%). With RVAD, a decrement of inferior vena cava pressure (Pvci) (39%) was observed with 34% increment of CO, but an increment of the single ventricle external work (SVEW). With the BIVAD, an increment of Pas (29%) and CO (37%) was observed. In the case of diastolic dysfunction, the LVAD increases CO (42%) and the RVAD decreases the Pvci, while both increase the SVEW. In the case of pulmonary vascular resistance increment, the highest CO (50%) and Pas (28%) increment is obtained with an RVAD with the highest decrement of Pvci (53%) and an increment of the SVEW but with the lowest VAD power consumption. The use of numerical models could be helpful in this innovative field to evaluate the effect of VAD implantation on Fontan patients to support patient and VAD type selection personalizing the assistance.

Hemodynamic Effects of Ventricular Assist Device Implantation on Norwood, Glenn, and Fontan Circulation: A Simulation Study

“…A previously developed lumped parameter model of the cardiovascular system (16,18,19) was adapted to this specific study (Fig. 1).…”

“…1b) is modeled redirecting the flow from the superior vena cava to the pulmonary arteries (18). 1b) is modeled redirecting the flow from the superior vena cava to the pulmonary arteries (18).…”

“…The model is implemented in Labview 7.1 (National Instruments, Austin, TX, USA), and equations are solved by Euler's method (16,18,19). The model is implemented in Labview 7.1 (National Instruments, Austin, TX, USA), and equations are solved by Euler's method (16,18,19).…”

Circulatory Modelling as a Clinical Decision Support and an Educational Tool

“…Each block presented in the figure contains several modules that can be assembled and used according to specific needs. Among others, the modules sketched in Fig.1 contain a complex of simpler models of systemic and pulmonary circulation, 7-8 models of congenital heart defects 9 and of surgical procedures, 10 interfaces to respiratory models, now under development, models of heart assist devices (LVAD, RVAD, BVAD, IABP, BIV pacing), [11][12][13] models of autonomic controls (in this moment baroreflex and metabolic controls, the second one under development), 8,14 and interfaces for educational use of the platform. 8 The polymorphism of the structure has been achieved through implementation of the concept of hybrid modelling, [15][16][17][18][19] in cooperation with the Nałecz Institute of Biocybernetics and Biomedical Engineering of the Polish Academy of Science.…”

The Total Artificial Heart in End-Stage Congenital Heart Disease

“…The addition of a sub-pulmonary assist device to force blood through an abnormal pulmonary vascular bed and into an often restricted systemic ventricle in the setting of heart failure is unlikely to be a successful long-term support strategy. On the other hand, the application of a sub-pulmonary support system very early in the clinical course, prior to the development of multi-organ dysfunction, may be able to avoid many of these concerns and is the topic of ongoing research (Di Molfetta et al, 2015). Those patients presenting with severe failure of their Fontan circulation, who have developed marked end-organ dysfunction, protein losing enteropathy, and/or plastic bronchitis are not good transplant candidates.…”