Exercise physiology with a left ventricular assist device

Analysis of heart-pump interaction with a computational simulator

Libera Fresiello, Frank Rademakers, Piet Claus, Gianfranco Ferrari, Arianna Di Molfetta, Bart Meyns

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

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.

Original languageEnglish
Article numbere0181879
JournalPLoS One
Volume12
Issue number7
DOIs
Publication statusPublished - Jul 1 2017

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Left ventricular assist devices
Heart-Assist Devices
Physiology
pumps
exercise
physiology
Simulators
heart
Pumps
Exercise
cardiac output
Cardiac Output
Hemodynamics
Unloading
Pulmonary Wedge Pressure
heart failure
hemodynamics
Heart Failure
Exercise equipment
Capillarity

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Exercise physiology with a left ventricular assist device : Analysis of heart-pump interaction with a computational simulator. / Fresiello, Libera; Rademakers, Frank; Claus, Piet; Ferrari, Gianfranco; Di Molfetta, Arianna; Meyns, Bart.

In: PLoS One, Vol. 12, No. 7, e0181879, 01.07.2017.

Research output: Contribution to journalArticle

Fresiello, Libera ; Rademakers, Frank ; Claus, Piet ; Ferrari, Gianfranco ; Di Molfetta, Arianna ; Meyns, Bart. / Exercise physiology with a left ventricular assist device : Analysis of heart-pump interaction with a computational simulator. In: PLoS One. 2017 ; Vol. 12, No. 7.
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abstract = "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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