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. 2014 May 5:20:733-41.
doi: 10.12659/MSM.890824.

Hemodynamic effects of various support modes of continuous flow LVADs on the cardiovascular system: a numerical study

Zhiming Song  1 , Kaiyun Gu  2 , Bin Gao  2 , Feng Wan  1 , Yu Chang  2 , Yi Zeng  2
Affiliations

Hemodynamic effects of various support modes of continuous flow LVADs on the cardiovascular system: a numerical study

Zhiming Song et al. Med Sci Monit. .

Abstract

Background: The aim of this study was to determine the hemodynamic effects of various support modes of continuous flow left ventricular assist devices (CF-LVADs) on the cardiovascular system using a numerical cardiovascular system model.

Material and methods: Three support modes were selected for controlling the CF-LVAD: constant flow mode, constant speed mode, and constant pressure head mode of CF-LVAD. The CF-LVAD is established between the left ventricular apex and the ascending aorta, and was incorporated into the numerical model. Various parameters were evaluated, including the blood assist index (BAI), the left ventricular external work (LVEW), the energy of blood flow (EBF), pulsatility index (PI), and surplus hemodynamic energy (SHE).

Results: The results show that the constant flow mode, when compared to the constant speed mode and the constant pressure head mode, increases LVEW by 31% and 14%, and EBF by 21% and 15%, respectively, indicating that this mode achieved the best ventricular unloading among the 3 support modes. As BAI is increased, PI and SHE are gradually decreased, whereas PI of the constant pressure head reaches the maximum value.

Conclusions: The study demonstrates that the continuous flow control mode of the CF-LVAD may achieve the highest ventricular unloading. In contrast, the constant rotational speed mode permits the optimal blood perfusion. Finally, the constant pressure head strategy, permitting optimal pulsatility, should optimize the vascular function.

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Figures

Figure 1
Figure 1
The bypass model of cardiovascular system and blood pump.
Figure 2
Figure 2
The relationship between the control variable of three support mode and the BAI.
Figure 3
Figure 3
(A) The left ventricular external work of bypass model; (B) The energy of blood flow of bypass model.
Figure 4
Figure 4
The curve of PI with the blood assist index.
Figure 5
Figure 5
The curve of the change of SHE along with the blood assist index.
Figure 6
Figure 6
The opening time of aortic valve.
See this image and copyright information in PMC

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