Enhancement of Arterial Pressure Pulsatility by Controlling Continuous-Flow Left Ventricular Assist Device Flow Rate in Mock Circulatory System

Bozkurt, Selim; Vosse, F.N. van de; Rutten, Mcm Marcel

doi:10.1007/s40846-016-0140-1

Cited by 23 publications

(12 citation statements)

References 37 publications

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“…Cox 11 studied pulsatility and left ventricular unloading during synchronized control with HeartMate II LVAD (Thoratec, Pleasanton, CA, USA) model. Bozkurt 32,33 reported that copulsation support enhances PP compared to constant assist without altering mean AoP. Ising 34 showed that PP is enhanced with copulsation in a mock circulation and an animal model.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of cardiac beat synchronization control for a rotary blood pump on valvular regurgitation with a mathematical model

Ogawa¹,

Kobayashi²,

Yamazaki

et al. 2020

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We have studied the cardiac beat synchronization (CBS) control for a rotary blood pump (RBP) and revealed that it can promote pulsatility and reduce cardiac load. Besides, patients with LVAD support sometimes suffer from aortic and mitral regurgitation (AR and MR). A control method for the RBP should be validated in wider range of conditions to clarify its benefits and pitfalls prior to clinical application. In this study, we evaluated pulsatility and cardiac load reduction obtained with the CBS control on valvular failure conditions with a mathematical model. Diastolic assist could reduce cardiac load on the left ventricle by decreasing external work of the ventricle even in MR cases while it was not so effective in AR cases. Systolic assist can still promote pulsatility in AR and MR cases; however, aortic valve function should be carefully confirmed since pulse pressure can be wider not due to systolic assist but to AR.

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Section: Discussionmentioning

confidence: 99%

Evaluation of cardiac beat synchronization control for a rotary blood pump on valvular regurgitation with a mathematical model

Ogawa¹,

Kobayashi²,

Yamazaki

et al. 2020

Artificial Organs

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“…According to the MCL results, the method may increase aortic pressure and flow pulsation more effectively than the PS modulation in comparison with some speed modulation systems. 24 Apparently, the main reason for the relatively small values of the pulse aortic pressure and flow in these systems is the inertia of the drive of the pump. In addition, the inertia of the pump driver affects the phase shift between the output flow and cardiac cycle, which also affects the efficiency of these systems.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the inertia of the pump driver affects the phase shift between the output flow and cardiac cycle, which also affects the efficiency of these systems. 24 In the proposed method, the dynamics of blood flow is determined by the speed of the valve clamping.…”

Section: Discussionmentioning

confidence: 99%

Haemodynamic evaluation of the new pulsatile-flow generation method in vitro

et al. 2019

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Continuous-flow ventricular-assist devices are widely used to support patients with advanced heart failure, because continuous-flow ventricular-assist devices are more durable, have smaller sizes and have better survival rates for patients compared to the pulsatile-flow ventricular-assist devices. Nevertheless, continuous-flow ventricular-assist devices often cause complications such as gastrointestinal bleeding, haemorrhagic stroke, and aortic insufficiency and have a negative impact on the microcirculation for both long-time implantable and short-time extracorporeal systems. The aim of this study is the evaluation of the pulsatile-flow generation method in continuous-flow ventricular-assist device without pump speed changes. The method may be used for short-time extracorporeal continuous-flow mechanical circulatory support and long-time implantable mechanical circulatory support. A shunt with a controlled adjustable valve, that clamps periodically, is connected in parallel to the continuous-flow ventricular-assist device. We compared the continuous-flow ventricular-assist device operating with and without the shunt on the mock circulation loop. The continuous-flow ventricular-assist device–shunt system was connected according to the left ventricle–aorta circuit and worked in phase with the ventricle. Heart failure was simulated on the mock circulation circuit. Rotaflow (Maquet Inc.) was used as the continuous-flow pump. Haemolysis studies of the system for generating a pulse flow were carried out at a flow rate of 5 L/min and a pressure drop of 100 mm Hg. To compare the haemodynamic efficiency, we used the aortic pulsation index Ip, the equivalent energy pressure and the surplus haemodynamic energy. These indexes were higher in the pulsatile mode ( Ip – 4 times, equivalent energy pressure by 7.36% and surplus haemodynamic energy – 10 times), while haemolysis was the same. The normalised index of haemolysis was 0.0015 ± 0.001. The results demonstrate the efficiency of the pulsatile-flow generation method for continuous-flow ventricular-assist devices without impeller rotation rate changes.

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“…Some of these problems have been extensively studied and dynamic CF‐LVAD operating support modes have already been suggested. For instance, there have been studies proposing CF‐LVAD operating speed modulation algorithms to increase the arterial pulsatility in a co‐pulsative pump support over a cardiac cycle . Aortic valve function and opening duration can be increased by reducing the CF‐LVAD operating speed to a minimum value before the onset of the systolic phase in the left ventricle .…”

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confidence: 99%

Effect of Cerebral Flow Autoregulation Function on Cerebral Flow Rate Under Continuous Flow Left Ventricular Assist Device Support

Bozkurt

2018

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Neurological complications in continuous flow left ventricular assist device (CF-LVAD) patients are the second-leading risk of death after multi-organ failure. They are associated with altered blood flow in the cardiovascular system because of CF-LVAD support. Moreover, an impaired cerebral autoregulation function may also contribute to complications such as hyperperfusion in the cerebral circulation under mechanical circulatory support. The aim of this study is to evaluate the effect of cerebral autoregulatory function on cerebral blood flow rate under CF-LVAD support. A lumped parameter model was used to simulate the cardiovascular system including the heart chambers, heart valves, systemic and pulmonary circulations and cerebral circulation which includes entire Circle of Willis. A baroreflex model was used to regulate the systemic arteriolar and cerebral vascular resistances and a model of the Micromed CF-LVAD was used to simulate the pump dynamics at different operating speeds. Additionally, preserved and impaired cerebral autoregulatory functions were simulated in heart failure and under CF-LVAD support. Cerebral blood flow rate was restored under CF-LVAD support at 10 500 rpm pump operating speed which generated a similar arterial blood pressure and blood flow as in a healthy condition for the impaired cerebral autoregulatory function while the preserved cerebral autoregulatory function regulated the cerebral flow rate within a relatively low range for the applied pump operating speeds. Relatively low or high pump operating speeds may cause underpefusion or hyperperfusion for a failing cardiovascular system with impaired cerebral autoregulatory function under CF-LVAD support which will contribute to the worsening of cerebral complications.

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Enhancement of Arterial Pressure Pulsatility by Controlling Continuous-Flow Left Ventricular Assist Device Flow Rate in Mock Circulatory System

Cited by 23 publications

References 37 publications

Evaluation of cardiac beat synchronization control for a rotary blood pump on valvular regurgitation with a mathematical model

Evaluation of cardiac beat synchronization control for a rotary blood pump on valvular regurgitation with a mathematical model

Haemodynamic evaluation of the new pulsatile-flow generation method in vitro

Effect of Cerebral Flow Autoregulation Function on Cerebral Flow Rate Under Continuous Flow Left Ventricular Assist Device Support

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