Starling-Like Flow Control of a Left Ventricular Assist Device: In Vitro Validation

Gaddum, Nicholas; Stevens, Michael C.; Lim, Einly; Fraser, John F.; Lovell, Nigel H.; Mason, D. G.; Timms, Daniel; Salamonsen, Robert F.

doi:10.1111/aor.12221

Cited by 43 publications

(51 citation statements)

References 22 publications

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“…Their results show that among the pressure controllers, those based on EDP present the best physiological performance . The performance of the pump‐flow‐pulsatility‐based controller is slightly inferior, but still good . The SP controller is based on the estimation of the preload condition of the LV and therefore, it lacks preload sensitivity compared to direct preload‐based controllers .…”

Section: Discussionmentioning

confidence: 99%

A Physiological Controller for Turbodynamic Ventricular Assist Devices Based on Left Ventricular Systolic Pressure

et al. 2016

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The current article presents a novel physiological feedback controller for turbodynamic ventricular assist devices (tVADs). This controller is based on the recording of the left ventricular (LV) pressure measured at the inlet cannula of a tVAD thus requiring only one pressure sensor. The LV systolic pressure (SP) is proposed as an indicator to determine the varying perfusion requirements. The algorithm to extract the SP from the pump inlet pressure signal used for the controller to adjust the speed of the tVAD shows robust behavior. Its performance was evaluated on a hybrid mock circulation. The experiments with changing perfusion requirements were compared with a physiological circulation and a pathological one assisted with a tVAD operated at constant speed. A sensitivity analysis of the controller parameters was conducted to identify their limits and their influence on a circulation. The performance of the proposed SP controller was evaluated for various values of LV contractility, as well as for a simulated pressure sensor drift. The response of a pathological circulation assisted by a tVAD controlled by the introduced SP controller matched the physiological circulation well, while over- and underpumping events were eliminated. The controller presented a robust performance during experiments with simulated pressure sensor drift.

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Section: Discussionmentioning

confidence: 99%

A Physiological Controller for Turbodynamic Ventricular Assist Devices Based on Left Ventricular Systolic Pressure

et al. 2016

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“…Myocardial recovery because of a reverse remodeling in the ventricle may occur under CF‐LVAD support with complete unloading of the left ventricle . CF‐LVAD operating modes imitating Frank‐Starling mechanism have also been proposed to provide more physiological preloads and afterloads for the changing conditions in a patient's body .…”

mentioning

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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“…An ideal SLC will have the same preload sensitivity as the healthy heart and will have minimal sensitivity to afterload, within the limits of the VADs rotational speed. The earliest SLCs imposed a linear relationship between measured VAD flow and preload as an approximation to Guyton's CRC . These early SLCs used a vertical VRL to determine the target VAD flow on the CRC following a change in preload.…”

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confidence: 99%

The Importance of Venous Return in Starling‐Like Control of Rotary Ventricular Assist Devices

2018

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Rotary ventricular assist devices (VADs) are less sensitive to preload than the healthy heart, resulting in inadequate flow regulation in response to changes in patient cardiac demand. Starling-like physiological controllers (SLCs) have been developed to automatically regulate VAD flow based on ventricular preload. An SLC consists of a cardiac response curve (CRC) which imposes a nonlinear relationship between VAD flow and ventricular preload, and a venous return line (VRL) which determines the return path of the controller. This study investigates the importance of a physiological VRL in SLC of dual rotary blood pumps for biventricular support. Two experiments were conducted on a physical mock circulation loop (MCL); the first compared an SLC with an angled physiological VRL (SLC-P) against an SLC with a vertical VRL (SLC-V). The second experiment quantified the benefit of a dynamic VRL, represented by a series of specific VRLs, which could adapt to different circulatory states including changes in pulmonary (PVR) and systemic (SVR) vascular resistance versus a fixed physiological VRL which was calculated at rest. In both sets of experiments, the transient controller responses were evaluated through reductions in preload caused by the removal of fluid from the MCL. The SLC-P produced no overshoot or oscillations following step changes in preload, whereas SLC-V produced 0.4 L/min (12.5%) overshoot for both left and right VADs. Additionally, the SLC-V had increased settling time and reduced controller stability as evidenced by transient controller oscillations. The transient results comparing the specific and standard VRLs demonstrated that specific VRL rise times were improved by between 1.2 and 4.7 s ( = 3.05 s), while specific VRL settling times were improved by between 2.8 and 16.1 seconds ( = 8.38 s) over the standard VRL. This suggests only a minor improvement in controller response time from a dynamic VRL compared to the fixed VRL. These results indicate that the use of a fixed physiologically representative VRL is adequate over a wide variety of physiological conditions.

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Starling-Like Flow Control of a Left Ventricular Assist Device: In Vitro Validation

Cited by 43 publications

References 22 publications

A Physiological Controller for Turbodynamic Ventricular Assist Devices Based on Left Ventricular Systolic Pressure

A Physiological Controller for Turbodynamic Ventricular Assist Devices Based on Left Ventricular Systolic Pressure

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

The Importance of Venous Return in Starling‐Like Control of Rotary Ventricular Assist Devices

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