Effect of Mechanical Circulatory Support on Exercise Hemodynamics among Individuals with Advanced Heart Failure

Abstract

<h3>Purpose</h3> The primary objective of this study was to determine why exercise capacity is limited among HF patients following left ventricular assist device (LVAD) implantation. <h3>Methods</h3> Thirteen HF patients (N=11 males; 59±10 yrs) completed invasive cardiopulmonary exercise testing (CPET) on upright cycle ergometry pre- and post-LVAD implantation on three visits: Visit 1: Pre-LVAD baseline testing; Visit 2: Post-LVAD testing with pump speed held at baseline; Visit 3: Post-LVAD testing with stepwise increases in pump speed (Heartware=40RPM/min; Heartmate 3=100RPM/min). On all visits, cardiac hemodynamics and gas-exchange parameters were monitored by Swan-Ganz catheter and indirect calorimetry, respectively. <h3>Results</h3> Cohort characteristics are displayed in <b>Table 1</b>. Compared to Visit 1, maximal oxygen uptake (VO₂Max) did not improve and was severely reduced on Visits 2 and 3 (<b>Figure 2</b>). Cardiac hemodynamics increased significantly with exercise on Visits 2-3 and were similar to values obtained from Visit 1. Cardiac output reserve was severely blunted on all visits and did not improve despite pump speed increases on Visit 3. Ventilatory efficiency improved modestly but remained impaired on Visits 2 and 3, compared to Visit 1 (Visits 1, 2, and 3: 47±13 v. 43±11 v. 39±7, respectively, ANOVA P=0.0047). <h3>Conclusion</h3> VO₂Max among LVAD patients is limited by severe increases in pulmonary arterial and left-sided filling pressures, and blunted cardiac output reserve. Pump speed modulations during exercise do not improve exercise performance. LVAD patients exhibit signs of residual and severe heart failure with exercise.