Key result
Bicycle exercise in patients with a HeartMate II cf-LVAD significantly increased total cardiac output from 4.1 to 8.5 L/min (P<0.01), with systemic vascular resistance being the strongest determinant.
Observational (n=30)
p-value: p=<0.01
In patients with a HeartMate II cf-LVAD, exercise-induced increases in total cardiac output are primarily driven by decreased systemic vascular resistance rather than increased pump flow.
Exercise output gains in cf-LVAD rely on SVR reduction; leaves open whether vascular-targeted interventions can enhance pump contribution.
Patients on continuous flow left ventricular assist devices (cf-LVADs) are able to return to an active lifestyle and perform all sorts of physical activities. This study aims to evaluate exercise hemodynamics in patients with a HeartMate II cf-LVAD (HM II). Thirty (30) patients underwent a bicycle exercise test. Along with exercise capacity, systemic cardiovascular responses and pump performance were evaluated at 6 and 12 months after HM II implantation. From rest to maximum exercise, heart rate increased from 87 ± 14 to 140 ± 32 beats/minute (bpm) (P<0.01), while systolic arterial blood pressure increased from 93 ± 12 to 116 ± 21 mm Hg (P<0.01). Total cardiac output (TCO) increased from 4.1 ± 1.1 to 8.5 ± 2.8 L/min (P<0.01) while pump flow increased less, from 5.1 ± 0.7 to 6.4 ± 0.6 L/min (P<0.01). Systemic vascular resistance (SVR) decreased from 1776 ± 750 to 1013 ± 83 dynes.s/cm(5) (P<0.001) and showed the strongest correlation with TCO (r= -0.72; P<0.01). Exercise capacity was affected by older age, while blood pressure increased significantly in men compared with women. Exercise capacity remained consistent at 6 and 12 months after HM II implantation, 51% ± 13% and 52% ± 13% of predicted VO2 max for normal subjects corrected for age and gender. In conclusion, pump flow of the HM II may contribute partially to TCO during exercise, while SVR was the strongest determinant of TCO.
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Martina et al. (2013) conducted an observational in Heart failure requiring continuous flow left ventricular assist device (cf-LVAD) (n=30). Bicycle exercise test vs. Rest was evaluated on Total cardiac output (TCO) from rest to maximum exercise (p=<0.01). Bicycle exercise in patients with a HeartMate II cf-LVAD significantly increased total cardiac output from 4.1 to 8.5 L/min (P<0.01), with systemic vascular resistance being the strongest determinant.
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