Numerical Modeling of Hemodynamics with Pulsatile Impeller Pump Support

Abstract

There is significant interest in the development and application of variable speed impeller-pump type ventricular assist devices designed to generate pulsatile blood flow. However, no study has so far been carried out to investigate the systemic cardiovascular response to various aspects of pump motion. In this article, a numerical model is constructed for the simulation of the cardiovascular response in the heart failure condition under representative cases of pulsatile impeller pump support. The native cardiovascular model is based on a previously validated model, and the impeller pump is modeled by directly fitting the pressure-flow curves that describe the pump characteristics. The model developed is applied to study circulatory dynamics under different degrees of phase shift and pulsation ratio in the pump motion profile. The characteristic variables are discussed as criteria for the evaluation of system response for comparison of the pulsatile flows. Simulation results show that a constant pump speed is the most efficient work mode for the rotary pump, and with the application of either a phase shift of 75% and a pulsation ratio of 0.5, or a phase shift of 42% and a pulsation ratio of 0.55, it is possible to generate arterial pulse pressure with the maximal magnitude of about 28 mmHg. However, this is achieved at the cost of reduced cardiac output and pump efficiency.

Flow Modulation Algorithms for Continuous Flow Left Ventricular Assist Devices to Increase Vascular Pulsatility: A Computer Simulation Study

“…Modulation of blood pump motor speeds/flow has been suggested as a potential mechanism to artificially increase vascular pulsatility in both ventricular assist devices 2,5,19,24,26,33,34 and total artificial heart. 10,16,17,27 Flow modulation of ventricular assist devices are affected by the timing of flow modulation to the native myocardial contraction.…”

Computational modelling and evaluation of cardiovascular response under pulsatile impeller pump support

“…In the interests of transparency and portability, the CellML implementation of the model on which this paper is based has been made publicly available from the CellML model repository. Figure 1 shows a schematic of the whole system, based on that described by Shi et al [11]. The system comprises two parts: the native cardiovascular system and the impeller pump.…”

“…In studies of VAD control strategy design, Giridharan & Skliar [9] and Ohuchi et al [10] modulated the speed of the rotary blood pump and produced pulsation of arterial pressure covering the physiological range. However, Shi et al [11] carried out numerical evaluations in a HeartMate III impeller pump and warned that, although modulating the pump rotating speed could produce physiological pressure pulsation, this control mechanism also induced strong regurgitant pump flow, which greatly reduced the pump efficiency. Since the cardiovascular response under VAD support depends on the interaction between the native circulation system and the VAD, and different VAD designs have different characteristics, more case studies are necessary, and it is imperative to test other impeller pumps under similar situations before a concrete conclusion can be drawn.…”

“…In this paper, we introduce a more comprehensive physiological indicator cost function. The numerical model described in Shi et al [11] is used to study the cardiovascular response in a heart failure condition under the support of a Berlin Heart INCOR impeller pump, and to optimize a simple control algorithm against the proposed cost function.…”

RPM and flow modulation for a continuous flow left ventricular assist device to increase vascular pulsatility : a computer simulation, mock circulation, and in-vivo animal study.

“…Modulation of blood pump motor speeds/flow has been suggested as a potential mechanism to artificially increase vascular pulsatility in both ventricular assist devices [33][34][35][36][37][38][39] and total artificial hearts [40][41][42][43]. Flow modulation of ventricular assist devices is affected by the timing of flow modulation to the native myocardial contraction.…”