Bionic women and men ‐ Part 1: Cardiovascular lessons from heart failure patients implanted with left ventricular assist devices

Abstract

Some humans with chronic, advanced heart failure are surgically implanted with a left ventricular assist device (LVAD). Because the LVAD produces a continuous flow, a palpable pulse is often absent in these patients. This allows for a unique investigation of the human circulation and has created a controversy around the 'need' for a pulse. The medical debate has also generated a more generic, fundamental discussion into what is 'normal' arterial physiology and health. The comprehensive study and understanding of the arterial responses to drastically altered haemodynamics due to continuous-flow LVADs, at rest and during activity, presents an opportunity to significantly increase our current understanding of the fundamental components of arterial regulation (flow, blood pressure, sympathetic activity, endothelial function, pulsatility) in a way that could never have been studied previously. In a series of four articles, we summarize the talks presented at the symposium entitled 'Bionic women and men-Physiology lessons from implantable cardiac devices' presented at the 2019 Annual Meeting of The Physiological Society in Aberdeen, UK. The articles highlight the novel questions generated by physiological phenomena observed in LVAD patients and propose future areas of interest within the field of cardiovascular physiology.

Impact of Mechanical Circulatory Support on Exercise Capacity in Patients With Advanced Heart Failure

“…The type of hemodynamic support provided by current-generation LVADs is quite distinct from normal physiology (49)(50)(51)(52)(53)(54)(55)(56)(57)(58). LVADs provide "continuous-flow" circulatory support because the rotating impeller, housed within the device itself, creates a suction effect, in essencepulling oxygenated blood out of the LV and continuously propelling it to the body.…”

Bionic women and men ‐ Part 2: Arterial stiffness in heart failure patients implanted with left ventricular assist devices

“…As already eluded to in the symposium report 'Bionic women and men. Part 1' (Stohr et al, 2020), the role of pulsatility has been a topic of great debate in terms of outcome in CF-LVAD patients.…”

“…As already detailed in 'Bionic women and men. Part 1' (Stohr, Cornwell, Kanwar, Cockcroft, & McDonnell, 2020), this increased risk of stroke and GI bleeding in CF-LVAD patients might be associated with the nature of continuous flow and its impact on blood flow dynamics, blood pressure regulation and overall organ health (Stöhr, McDonnell, Colombo, & Willey, 2019a, b). In non-LVAD patients, flow dynamics, blood pressure regulation and organ health…”

A Physiological Control for Artificial Heart Pump based on Adaptive Regulation of Heart Rate and the improved BAS Algorithm Optimization

“…However, it is worth noting that the regulation mechanism of heart rate is very complex, and it is difficult to obtain an accurate mathematical model. Therefore, traditional control algorithms based on mathematical models are not suitable for designing artificial heart pump control strategies based on heart rate [6]. As a non-parametric dynamic linearization method, model-free adaptive control (MFAC) can realize the adaptive control of the parameters and structure of the controlled object only by relying on the I/O data of the controlled object, without the need to know the controlled object system structure [7,8].…”