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Abstract 16747: The Artificial Pulse of the HeartMate3 LVAD Alters Mean Arterial Pressure Calculation, and the Relationship Between Arterial Pulse Pressure and Pulsatility Index


 Introduction:
 The HeartMate (HM3) left ventricular assist device (LVAD) uniquely features an artificial pulse (AP) (designed to reduce blood stasis and simulate physiologic pulsatility) that alters arterial blood pressure (BP) tracings (
 Fig. 1A
 ). Pulsatility Index (PI) corresponds to the magnitude of flow pulse through the LVAD and is used as a surrogate measure of arterial pulse pressure (PP). The effect of the AP on: i) relative contribution of systolic BP (SBP) and diastolic BP (DBP) to mean arterial pressure (MAP) calculation; and ii) association between PP and PI is presently unknown. Thus, we aimed to compare: i) MAP calculations; and ii) relation of PI with PP in HM3 vs HM II (LVAD with no AP) pts with arterial line (A-line) monitoring.
 
 
 Methods:
 A-line BP and LVAD PI data were prospectively collected in 48 HM3 and 29 HMII pts. MAP was calculated with the formula conventionally used in non LVAD pts (MAP = 2/3 DBP + 1/3 SBP) and compared to A-line MAP. Among HM3 pts, a multiple linear regression model was fit with A-line SBP and DBP as predictor variables, and A-line MAP as the dependent variable to derive the
 HM3 MAP Formula
 . The relation between arterial PP and PI in HM3 and HMII pts was assessed using Pearson’s correlation.
 
 
 Results:
 MAP calculated using the conventional formula accurately estimated A-line MAP in HMII pts, but overestimated A-line MAP in HM3 pts. The
 HM3 MAP Formula
 more closely approximated A-line MAP. Mean observed difference (MOD) and mean absolute difference (MAD) between calculated MAPs and A-line MAPs are reported in
 Fig. 1B
 . While median PP was similar in HM3 and HMII pts (16 vs 20 mmHg, p=0.11), median PI was significantly higher in HMII pts (3.45 vs 5.6, p<0.001). PI correlated with PP in HMII pts (
 r
 0.47, p=0.01). However, no significant correlation was found between PI and PP in HM3 pts (
 r
 0.24, p=0.1;
 Fig. 1C
 ).
 
 
 Conclusions:
 In HM3 pts, the AP significantly alters the relative contribution of SBP and DBP to MAP. Unlike in HM2 pts, PI does not relate to arterial PP in HM3 pts.
 
 
 
