Further Peripheral Vascular Dysfunction in Heart Failure Patients With a Continuous-Flow Left Ventricular Assist Device: The Role of Pulsatility

Abstract

Objectives: Using flow-mediated vasodilation (FMD) and reactive hyperemia (RH), this study aimed to provide greater insight into left ventricular assist device (LVAD)-induced changes in peripheral vascular function.

Background: Peripheral endothelial function is recognized to be impaired in patients with heart failure with reduced ejection fraction (HFrEF), but the peripheral vascular effects of continuous-flow LVAD implantation, now used as either a bridge to transplantation or as a destination therapy, remain unclear.

Methods: Sixty-eight subjects (13 New York Heart Association [NYHA] functional class II HFrEF patients, 19 NYHA functional class III/IV HFrEF patients, 20 NYHA functional class III/IV HFrEF patients post-LVAD implantation, and 16 healthy age-matched control subjects) underwent FMD and RH testing in the brachial artery with blood flow velocity, artery diameters, and pulsatility index (PI) assessed by ultrasound Doppler.

Results: PI was significantly lower in the LVAD group (2.0 ± 0.4) compared with both the HFrEF II (8.6 ± 0.8) and HFrEF III/IV (8.1 ± 0.9) patients, who, in turn, had significantly lower PI than the control subjects (12.8 ± 0.9). Likewise, LVAD %FMD/shear rate (0.09 ± 0.01 %Δ/s(-1)) was significantly reduced compared with all other groups (control subjects, 0.24 ± 0.03; HFrEF II, 0.17 ± 0.02; and HFrEF III/IV, 0.13 ± 0.02 %Δ/s(-1)), and %FMD/shear rate significantly correlated with PI (r = 0.45). RH was unremarkable across groups.

Conclusions: Although central hemodynamics are improved in patients with HFrEF by a continuous-flow LVAD, peripheral vascular function is further compromised, which is likely due, at least in part, to the reduction in pulsatility that is a characteristic of such a mechanical assist device.

Keywords: HFrEF; blood flow; flow-mediated vasodilation; mechanical assist; pulsatility.

Figure 1

Brachial artery PI in NYHA Class II HFrEF patients, NYHA Class III/IV HFrEF patients, NYHA Class III/IV HFrEF patients post-LVAD implantation, and healthy controls. (*) Significantly different from Controls; (†) Significantly different from HFrEF II. (‡) Significantly different from HFrEF III/IV. Values are mean ± SE.

Figure 2

Brachial artery FMD expressed as an absolute change in diameter (A) and percentage change from pre-cuff baseline (B) in NYHA Class II HFrEF patients, NYHA Class III/IV HFrEF patients, NYHA Class III/IV HFrEF patients post-LVAD implantation, and healthy controls. (*) Significantly different from Controls; (†) Significantly different from HFrEF II. (‡) Significantly different from HFrEF III/IV. Values are mean ± SE.

Figure 3

Relationship between brachial artery FMD and brachial artery peak shear rate in all subjects (A) and brachial artery FMD expressed as a percentage change from precuff baseline after normalizing for shear rate (B) in NYHA Class II HFrEF patients, NYHA Class III/IV HFrEF patients, NYHA Class III/IV HFrEF patients post-LVAD implantation, and healthy controls. (*) Significantly different from Controls; (†) Significantly different from HFrEF II. (‡) Significantly different from HFrEF III/IV.

Figure 4

Relationship between brachial artery PI and brachial artery %FMD/shear.