Effect of exercise and pump speed modulation on invasive hemodynamics in patients with centrifugal continuous-flow left ventricular assist devices

Muthiah, K.; Robson, D.; Prichard, R.; Walker, R.; Gupta, Sunil; Keogh, Anne; Macdonald, P.; Woodard, John; Kotlyar, Eugene; Dhital, K.; Granger, Emily; Jansz, P.; Spratt, Phillip; Hayward, Christopher

doi:10.1016/j.healun.2014.11.004

Cited by 48 publications

(71 citation statements)

References 32 publications

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“…For HF+VAD Ras was calculated considering data from [3,5,13], Rap averaging data from [3,5]. Ras was then split into the resistance of upper body, kidneys, splanchnic circulation and lower limbs as reported in [8].…”

Section: Methodsmentioning

confidence: 99%

“…From a physiological point of view, Pset represents the equilibrium value and it was characterized in the simulator at rest condition: for HF we averaged the mean systemic pressure at rest taken from [3,16,17,18], for HF+VAD we averaged the data of [3,5,13]. During exercise Pset automatically increases due to the “baroreflex resetting phenomenon” that progressively shifts the baroreflex control towards higher pressure levels.…”

Section: Methodsmentioning

confidence: 99%

“…What emerged so far is that VAD patients show similar limitations as heart failure patients such as autonomic nervous system impairment, chronotropic incompetence, poor perfusion of exercising muscles, right ventricular dysfunction and iron deficiency [4]. Heart failure and VAD patients show also similar hemodynamics from rest to exercise, particularly in terms of wedge pressure, pulmonary pressure and right atrial pressure elevation [5]. In addition, cardiac output increase is limited despite the contribution of the VAD.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, cardiac output increase is limited despite the contribution of the VAD. Some studies investigated if a VAD speed modulation during exercise could overcome this but results showed little effects on exercise performance [6] and on cardiac output [5]. …”

Section: Introductionmentioning

confidence: 99%

“…At present there are only a few studies describing exercise pathophysiology with a VAD [2,3,7], and even less reporting both systemic and central hemodynamics [5]. We searched and grouped the data available in the literature, and analyzed them using a cardiorespiratory simulator.…”

Section: Introductionmentioning

confidence: 99%

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Exercise physiology with a left ventricular assist device: Analysis of heart-pump interaction with a computational simulator

et al. 2017

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Patients with a Ventricular Assist Device (VAD) are hemodynamically stable but show an impaired exercise capacity. Aim of this work is to identify and to describe the limiting factors of exercise physiology with a VAD. We searched for data concerning exercise in heart failure condition and after VAD implantation from the literature. Data were analyzed by using a cardiorespiratory simulator that worked as a collector of inputs coming from different papers. As a preliminary step the simulator was used to reproduce the evolution of hemodynamics from rest to peak exercise (ergometer cycling) in heart failure condition. Results evidence an increase of cardiac output of +2.8 l/min and a heart rate increase to 67% of the expected value. Then, we simulated the effect of a continuous-flow VAD at both rest and exercise. Total cardiac output increases of +3.0 l/min (+0.9 l/min due to the VAD and +2.1 l/min to the native ventricle). Since the left ventricle works in a non-linear portion of the diastolic stiffness line, we observed a consistent increase of pulmonary capillary wedge pressure (from 14 to 20 mmHg) for a relatively small increase of end-diastolic volume (from 182 to 189 cm3). We finally increased VAD speed during exercise to the maximum possible value and we observed a reduction of wedge pressure (-4.5 mmHg), a slight improvement of cardiac output (8.0 l/min) and a complete unloading of the native ventricle. The VAD can assure a proper hemodynamics at rest, but provides an insufficient unloading of the left ventricle and does not prevent wedge pressure from rising during exercise. Neither the VAD provides major benefits during exercise in terms of total cardiac output, which increases to a similar extend to an unassisted heart failure condition. VAD speed modulation can contribute to better unload the ventricle but the maximal flow reachable with the current devices is below the cardiac output observed in a healthy heart.

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