Simulation study of the Hemopump as a cardiac assist device

Li, X.; Bai, Jing; He, Ping

doi:10.1007/bf02344218

Cited by 16 publications

(10 citation statements)

References 26 publications

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“…The simplest VAD representation is a prescribed flow function. 15 A more sophisticated method was to construct an equation containing the variables of pump flow, pressure difference across the pump, and the pump rotation speed, matching the experimental measurements of the pump characteristics using regression analysis, while the pump rotor dynamics were either neglected 1,3,4,13,14,30 or modeled considering the various momenta acting on the rotor. 7,11,32 In this article, the pump is modeled by constructing a relationship Q = Q(DP, x) to describe the characteristic pressure-flow relation, while the rotor dynamics of the pump are assumed to be ideal and not included.…”

Section: Model Of the Impeller Pump Vadmentioning

confidence: 99%

Numerical Modeling of Hemodynamics with Pulsatile Impeller Pump Support

2010

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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.

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Section: Model Of the Impeller Pump Vadmentioning

confidence: 99%

Numerical Modeling of Hemodynamics with Pulsatile Impeller Pump Support

2010

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“…In our previous report (LI et al, 2002), we have shown that, by operating the Hemopump in a synchronous mode, i.e. at a higher speed during systole and a lower speed during diastole, both aortic flow and aortic pressure show a higher degree of pulsation, resembling more closely natural waveforms.…”

Section: Discussionmentioning

confidence: 93%

“…1 shows the computer model used in this study. The details of the model have been described in a previous paper (LI et al, 2002). In brief, the entire model contained a canine cardiovascular model and a dynamic Hemopump model.…”

Section: Introductionmentioning

confidence: 99%

“…To study the performance and assistant effects of the Hemopump under various operation modes and different physiological conditions of the cardiovascular system, we have developed a dynamic model of the Hemopump and incorporated it into a canine circulatory system model (LI et al, 2002 simulation results indicate that the direct effects of the Hemopump include an increase in stoke volume, an increase in mean aortic pressure and coronary blood flow, a decrease in the area of the pressure-volume loop of the left ventricle, and a decrease in left-atrial volume. Our results also show that all these changes axe enhanced when the rotation speed of the pump impellers (or simply the 'pump speed') is increased.…”

Section: Introductionmentioning

confidence: 99%

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Optimum control of the Hemopump as a left-ventricular assist device

Bai

Xia

2005

Med. Biol. Eng. Comput.

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A general framework for designing an optimum control strategy for the Hemopump is described. An objective function was defined that includes four membership functions, each constructed based on the desired values of one of the four members: stroke volume, mean left atrial pressure, aortic diastolic pressure and mean pump rotation speed. The Hemopump was allowed to operate either at a constant speed or at two different speeds during a cardiac cycle. The goal was to maximise the objective function by varying the magnitude and timing of the pump speed. Using a canine circulatory model, it was demonstrated that, in general, different cardiac conditions or different clinical objectives require different operation parameters. For example, when a left ventricle with minor ischaemia was simulated, and the main objective was to increase stoke volume, the objective function was maximised, from a value of 0.877 when the pump was off, to 0.946 when the pump was operated at speed 2 (18 500 revolutions min(-1)). On the other hand, for a severely ischaemic heart, the optimum pump speed became speed 3 (20 000 revolutions min(-1)), which maximized the objective function to 0.943 (from 0.707 when the pump was off). The results also suggest that it is more beneficial to operate the Hemopump at two different speeds during a cardiac cycle (a higher speed during systole and early diastole, and a lower speed during late diastole) than to maintain a constant speed throughout the cardiac cycle.

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“…Forthese reasons we improved our computerm odelo ft he cardiovascular system [3][4][5] with aH emopump model [6][7][8]. This rotary pump can be used as left ventricular assist device (LVA D) or as right ventricular assist device (RVA D).Inour model the assistance works as RVAD: it takesbloodfrom the right ventricle andejectsitinto the pul-monaryartery.…”

Section: Introductionmentioning

confidence: 99%

Right Ventricular Assistance by Continuous Flow Device

Lazzari¹,

Ferrari²

2007

Methods Inf Med

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Summary Objectives·. This work is another step in the development of the circulatory model CARDIOSIM® and of its model library. Continuous flow assistance is often used to support the right ventricular failure. Computer simulation is one of the methods to study the effect of this assistance on the failing ventricle. The purpose of this study was to evaluate the effect of this support on some hemodynamic variables, when different right ventricular end-systolic elastance and pump speed values were applied. Methods: The rotary blood pump model was included into the software package CARDIOSIM®, which reproduces the cardiovascular system. Lumped parameters models were used to reproduce the circulatory phenomena. Variable elastance models reproduced the Starling’s law of the heartfor both ventricles. In the study right ventricular end-systolic elastance (EmaxraT) and the rotational speed of the pumptookthree different values. All the other parameters of the model were constants. Results: The rotational speed of the pump had a significant influence on right ventricular end-diastolic and end-systolic volumes, right atrial pressure (Pra), right ventricular (Qro) and pump flows. The effects on pulmonary arterial pressure (Pap) were more evident when the right ventricular end-systolic elastance was low. When the speed of the device increased the mean value of Pra decreased for each value of EmaxMT. The total flow (Qro + pump flow) increased when the speed of the pump increased. Conclusions: Our simulation (in good agreement with the results presented in literature) showed that Hemo-pump produces a rise in total flow, a drop in blood flow pumped out by the right ventricle and a drop in right atrial pressure.

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Simulation study of the Hemopump as a cardiac assist device

Cited by 16 publications

References 26 publications

Numerical Modeling of Hemodynamics with Pulsatile Impeller Pump Support

Numerical Modeling of Hemodynamics with Pulsatile Impeller Pump Support

Optimum control of the Hemopump as a left-ventricular assist device

Right Ventricular Assistance by Continuous Flow Device

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