Noninvasive Measures of Pulsatility and Blood Pressure During Continuous-Flow Left Ventricular Assist Device

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Abstract

The reliability and validity of a palpable pulse and other noninvasive measures of pulsatility in patients on continuous-flow (CF) left ventricular assist device (LVAD) support have not been rigorously evaluated. We prospectively enrolled 23 patients who had CF-LVAD and an arterial catheter for blood pressure (BP) monitoring. Pulse pressure (PP) via the arterial line was compared with three noninvasive measures of pulsatility: presence of a palpable pulse, pulsatility index (PI), and aortic valve opening (AVO). In addition, the relationship between Doppler BP (DopBP) and arterial line pressures was evaluated. The study group comprised 30% females, 73% nonischemic cardiomyopathy, 87% axial flow device (HeartMate II [HMII]), and 13% centrifugal flow device (HVAD) support. Among four practitioners, the interobserver agreement for the presence of a palpable pulse was moderate (k = 0.41; 95% CI, 0.28–0.60). If the PP was ≥15 mm Hg, a radial pulse was palpated 82% of the time, whereas when the PP was <15 mm Hg, a radial pulse was palpated only 35% of the time. In subjects with a palpable pulse, there was a strong correlation between DopBP and systolic BP (SBP) (r = 0.94; 95% CI, 0.82–0.99), whereas the correlation between DopBP and mean arterial pressure (MAP) was much weaker (r = 0.42; 95% CI, 0.19–0.96). In subjects without a palpable pulse, there was a strong correlation between both the DopBP and SBP (r = 0.94; 95% CI, 0.80–1.0) and DopBP and MAP (r = 0.87; 95% CI, 0.77–1.00). Finally, PP was significantly associated with PI (odds ratio [OR], 0.3; 95% CI, 0.14–0.45; p = 0.0002) but not AVO (OR, 1.41: 95% CI, 0.70–2.83; p = 0.33). The presence of a palpable pulse has good interobserver agreement and allows for dichotomization of the DopBP to reflect the SBP in its presence and the MAP in its absence. This simple measure should be incorporated into BP management algorithms for CF-LVADs. The PI shows a modest correlation to PP.

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