Exercise blood pressure response during assisted circulatory support:
Comparison of the total artificial heart with a left ventricular assist device during rehabilitation
The Journal of Heart and Lung Transplantation
Total heart replacement is an effective bridge to transplant for patients with biventricular heart failure and is an alternative to implantation of biventricular assist devices.1 The total artificial heart (TAH) is a mechanical circulatory support device that orthotopically replaces a recipient's native ventricles and all 4 cardiac valves. In contrast to a left ventricular assist device (LVAD), the native heart is entirely removed and has no impact on device function or total cardiac output.
The clinician programs the TAH pump rate ("heart rate") and ejection pressures ("contractility"), which are fixed and do not dynamically change during pump operation. The pump is calibrated in the resting state to only partially fill so that the ejection volume ("stroke volume") may increase to accommodate a rise in pre-load.
In apparently healthy individuals, systolic blood pressure rises with exercise (?10 mm Hg/metabolic equivalent).2, 3 Although stroke volume in patients with a TAH can increase during exercise, heart rate and contractility do not change. Hence, these patients could have a blunted or even hypotensive response to exercise due to arterial vasodilation in working skeletal muscle with a significantly muted increase in cardiac output.4 These concerns are particularly relevant with the development of a portable driver that permits hospital discharge with the device.
To our knowledge, there are no studies reporting on the blood pressure response to exercise or the feasibility of rehabilitation for patients who have a TAH. We hypothesized that patients with total heart replacement have a blunted response to exercise compared to those with LVADs... read more