Exercise Studies in Patients With Rotary Blood Pumps: Cause, Effects, and Implications for Starling‐Like Control of Changes in Pump Flow

Salamonsen, Robert F.; Pellegrino, Vincent; Hayes, Kate; Timms, Daniel; Lovell, Nigel H.; Hayward, Christopher

doi:10.1111/aor.12070

Cited by 39 publications

(45 citation statements)

References 17 publications

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“…Dependencies between low LVAD speed (below baseline value) and reduced exercise capacities were found in the previous clinical studies . However, other studies investigating the effects of an LVAD speed increase under exertion, reported moderate to no improvements in terms of exercise capacity or TCO . Given the large patient diversity in terms of cardiovascular impairments, the benefits of an increased LVAD speed during exercise are still unclear.…”

Section: Introductionmentioning

confidence: 82%

“…5,6 However, other studies investigating the effects of an LVAD speed increase under exertion, reported moderate to no improvements in terms of exercise capacity or TCO. [7][8][9][10][11][12][13] Given the large patient diversity in terms of cardiovascular impairments, the benefits of an increased LVAD speed during exercise are still unclear.…”

Section: Introductionmentioning

confidence: 99%

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LVAD speed increase during exercise, which patients would benefit the most? A simulation study

et al. 2019

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Patients supported with a left ventricular assist device (LVAD) have impaired cardiovascular adaptations during exercise, resulting in reduced total cardiac output and exercise intolerance. The aim of this study is to report associations among these impaired cardiovascular parameters and exercise hemodynamics, and to identify in which conditions an LVAD speed increase can provide substantial benefits to exercise. A cardiorespiratory simulator was used to reproduce the average hemodynamics of LVAD patients at exercise. Then, a sensitivity study was conducted where cardiovascular parameters were changed individually ±20% of their baseline value at exercise (heart rate, left/right ventricular contractility, total peripheral resistance, and valve pathologies). Simulations were performed at a baseline LVAD speed of 2700 rpm and repeated at 3500 rpm to evaluate the benefits of a higher LVAD support on hemodynamics. Total cardiac output (TCO) was mostly impaired by a poor left ventricular contractility or vasodilation at exercise (−0.6 L/min), followed by a poor chronotropic response (−0.3 L/min) and by a poor right ventricular contractility (−0.2 L/min). LVAD speed increase better unloads the left ventricle and improves total cardiac output in all the simulated conditions. The most substantial benefits from LVAD speed increase were observed in case of poor left ventricular contractility (TCO + 1.6 L/min) and vascular dysfunction (TCO + 1.4 L/min) followed by lower heart rate (TCO + 1.3 L/min) and impaired right ventricular contractility (TCO + 1.1 L/min). Despite the presence of the LVAD, exercise hemodynamic is strongly depending on the ability of the cardiovascular system to adapt to exercise. A poor left ventricular inotropic response and a poor vascular function can strongly impair cardiac output at exercise. In these conditions, LVAD speed increase can be an effective strategy to augment total cardiac output and unload the left ventricle. These results evidence the need to design a physiological LVAD speed controller, tailored on specific patient’s needs.

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

LVAD speed increase during exercise, which patients would benefit the most? A simulation study

et al. 2019

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“…Although preload-based control methods, for example that based on a predetermined pulsatility index level [52], [53], have been commonly used in IRBPs, they have demonstrated a lack of adaptation to varying physiological conditions due to their strong dependency on the pump operating point [54]. In particular, the sensitivity of the LV preload to pump flow is significantly reduced during the VE state, when the native heart contributes a significant proportion of the total cardiac output [55]. Compared to full unloading, recent studies have suggested that partial unloading may be more beneficial for patients with potential for myocardial recovery, as it ensures optimum LV washout [56] and reduces the risk of LV stasis [57] and aortic valve fusion [10].…”

Section: Discussionmentioning

confidence: 99%

Classification of Implantable Rotary Blood Pump States With Class Noise

Ooi

Seera

et al. 2016

IEEE J. Biomed. Health Inform.

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A medical case study related to implantable rotary blood pumps is examined. Five classifiers and two ensemble classifiers are applied to process the signals collected from the pumps for the identification of the aortic valve nonopening pump state. In addition to the noise-free datasets, up to 40% class noise has been added to the signals to evaluate the classification performance when mislabeling is present in the classifier training set. In order to ensure a reliable diagnostic model for the identification of the pump states, classifications performed with and without class noise are evaluated. The multilayer perceptron emerged as the best performing classifier for pump state detection due to its high accuracy as well as robustness against class noise.

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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

Artificial Organs

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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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Exercise Studies in Patients With Rotary Blood Pumps: Cause, Effects, and Implications for Starling‐Like Control of Changes in Pump Flow

Cited by 39 publications

References 17 publications

LVAD speed increase during exercise, which patients would benefit the most? A simulation study

LVAD speed increase during exercise, which patients would benefit the most? A simulation study

Classification of Implantable Rotary Blood Pump States With Class Noise

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

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