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.