Novel Approach to Assess Intraventricular Pressure Difference in Patients with Left Ventricular Assist Device during Ramp Study

Abstract

Purpose Blood flow through the left ventricular assist device (LVAD) is dependent on the rotation speed of the impeller, and inversely dependent on the differential pressure across the LVAD (HQ relationship). We developed a novel approach to estimate intraventricular pressure difference (IVPD) in patients with LVAD and assess the change of IVPD according to pump speed during ramp study. Methods We developed in-house code of 1-dimensional incompressible Euler equation written in MATLAB (MathWorks, Natick, MA, USA) which allows us to measure IVPD by analyzing transesophageal echocardiographic images. Color M-mode images in mid-esophageal long axis view were obtained at 3 different pump speeds (low, optimized, high) in 10 patients who had LVAD implant (Figure). The optimal rotation speed was defined by stable hemodynamic conditions and the septal shape on transesophageal imaging. Pairwise comparison between each group was performed using Steel-Dwass analysis. Results Images were successfully obtained in all patients. Median IVPD values were 0.88 mmHg [IQR 0.73 - 1.02] at pre-LVAD implant, 1.86 mmHg [IQR 1.50 - 2.15] at low speed, 2.12 mmHg [IQR 1.72 - 2.71] at optimal speed, 2.09 mmHg [IQR1.72 - 2.31] at high speed, respectively (figure). There was significant difference between pre-implantation and the remaining 3 groups ( p Conclusion These data illustrate a novel approach to estimate IVPD during early diastole in patients with LVAD. Importantly, data suggests that setting of pump speed can be informed by analyzing IVPD during early diastole.