Download Simulation of Pulsatile Left Ventricular Assist Device - AMAC-2017

Simulation of Pulsatile Left Ventricular Assist Device Therapy
Using Aplysia CardioVascular Lab
Elira Maksuti* and Michael Broomé**
*Department of Medical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
**ECMO Department, Karolinska University Hospital, Stockholm, Sweden
Introduction: Mechanical left ventricular assist devices (LVADs) have been developed for bridging
patients to transplantation, but are increasingly being used as destination therapy or temporary aid until
recovery. When selecting a pulsatile flow LVAD therapy, the interaction between the mechanical device
and the native heart must be taken into account in order to optimize the benefits of the treatment. The aim
of this study was to exemplify this complex pathophysiology by assessing the effect of 3 different
pulsatile LVAD therapies using Aplysia CardioVascular Lab. Methods: Aplysia software is based on a
closed-loop lumped-parameter model consisting of 27 vascular segments, the 4 cardiac chambers, the
cardiac valves, the pericardium and intrathoracic pressure [1]. The LVAD were modelled based on the
working principle of a commercially available device (Berlin Heart EXCOR, Germany) and was
connected between the left ventricle (LV) and the ascending aorta. Heart failure was simulated by
reducing the end systolic pressure-volume (PV) relationship of the LV from 2.8 to 0.80 mmHg/mL and
increasing the end diastolic PV relationship of the LV from 0.05 to 0.08 mmHg/mL. Three different
LVAD therapies were simulated in addition to heart failure: unsynchronized LVAD, LVAD with systolic
pulsation and LVAD with diastolic pulsation. Results: All investigated LVAD therapies unloaded the LV
and improved cardiac output (Figure 1). LVAD with diastolic pulsation performed better than systolic
pulsation since it resulted in lower mechanical load of the LV (total work of 1320 versus
2084 mmHg∙mL, O2 consumption of 3.8 versus 4.8 mL/min) and increased coronary flow (mean flow of
107 versus 95 mL/min), improving LV myocardial oxygen demand and supply balance. Conclusion:
Patient specific clinical data together with computer simulation may be a valuable tool in evaluating
LVAD treatments. Validation of the simulations results still presents challenges.
Figure 1: (a) Simulated pressure-volume loops for a healthy individual in black and for a patient with heart
failure in red; heart failure patient coupled to (b) unsyncronized LVAD, (c) LVAD with systolic pulsation and
(d) LVAD with diastolic pulsation.
Considerations about the “Reuse, Reduce, Recycle” theme of AMAC 2017
Aplysia CardioVascular Lab is a standalone software application with a friendly graphical user interface
(GUI). The GUI options can be “basic, standard or advanced” depending on the expertise of the user.
Aplysia is commercially available for educational, research and clinical purposes.
References
[1]
M. Broomé, E. Maksuti, A. Bjällmark, B. Frenckner, and B. Janerot-Sjöberg, “Closed-loop real-time
simulation model of hemodynamics and oxygen transport in the cardiovascular system.,” Biomed. Eng.
Online, vol. 12, no. 1, p. 69, Jan. 2013.