Pulsatile Pressure Delivery of Continuous Flow LVAD is Speed Dependent and Markedly Reduced Relative to Heart Failure Patients

Abstract

Purpose
Although continuous flow left ventricular assist devices (CF-LVADs) provide an augmentation in systemic perfusion, there is a scarcity of in-vivo data regarding systemic pulsatility on support.

Methods
A retrospective cohort study was performed in patients supported on CF-LVAD therapy (n=67) who underwent a combined left and right heart catheterization ramp protocol. Aortic pulsatility was defined by the pulsatile power index (PPI), a quantity derived from the amplitudes of the harmonics of the pressure waveform. PPI was calculated in a cohort of high-output heart failure (HOHF, n=66) and standard HF cohort (n=44) and invasive hemodynamics and pulsatility were compared.

Results
Systemic, pulmonary artery, and pulmonary capillary wedge pressures were lower in the LVAD cohort (P≤.04 for each) compared with HOHF or HF. PPI was drastically lower in CF-LVAD supported patients with median PPI .006 (IQR .002-.012) vs PPI .09 (IQR .06-.17) in HF and PPI .25 (IQR .13-.37) in HOHF (P<.0001 among groups). PPI more significantly differed between groups than aortic pulse width. With speed augmentation during ramp, PPI values fell more quickly in centrifugal flow pumps than axial flow (slopes -3.3 × 10⁻⁵ and -1.1 × 10⁻⁵ vs -6.9 × 10⁻⁶ for HW, HM3, and HMII respectively). PPI correlated poorly with LV ejection fraction (LVEF) in CF-LVAD patients and HOHF (P>.05) and modestly (r=.38, P=.01) in HF but in CF-LVAD patients, there was a stronger correlation with LV dP/dt (r=.41, P=.002) than LVEF (r=.21, P=.09, Pint <.001).

Conclusion
CF-LVAD support is associated with a dramatic reduction in arterial pulsatility as measured by PPI relative to HOHF and HF cohorts and decreases with increasing speed. Further work is needed to determine the applicability to the next generation of device therapy.