Abstract Body (Do not enter title and authors here): Background: The Impella device provides percutaneous left ventricular support but may induce aortic regurgitation (AR) due to its transvalvular placement. In this study, we defined Impella-induced AR as consisting of two components: backward flow through the Impella cannula (Impella retrograde flow) and backward flow from the aorta into the left ventricle (LV retrograde flow). However, both the relationship between these regurgitant flows and afterload, and their actual volume, remain unknown.
Hypothesis: We hypothesized that elevated afterload increases Impella-induced AR by augmenting both Impella and LV retrograde flow, thereby diminishing the effectiveness of Impella support.
Methods: A mock circulation system was used to simulate Impella CP support under 135 unique hemodynamic conditions, created by testing every combination of three levels of circuit resistance (simulating peripheral resistance), nine Impella P-levels (P1–P9), and five levels of left ventricular function. Left ventricular function was simulated by adjusting the ejection-phase volume delivered by an external pump. The 100% ejection-phase volume was defined as 174 mL, and five levels were set at 20%, 30%, 40%, 50%, and 60%. For each condition, mean arterial pressure (MAP), Impella retrograde flow, LV retrograde flow, and their total (Impella-induced AR) were measured. Correlations between MAP and each individual regurgitant flow were analyzed.
Results: Impella-induced AR was significantly correlated with MAP (r = 0.82, p < 0.0001), with LV retrograde flow being most closely correlated (r = 0.90). Impella retrograde flow also increased with MAP (r = 0.64).
At a clinically typical MAP of 65 mmHg, the average total regurgitant flow was 1.09 L/min, of which 0.97 L/min was LV retrograde flow and 0.12 L/min was Impella retrograde flow, demonstrating that significant Impella-induced AR occurs even at commonly targeted MAP levels.
Conclusions: Elevated MAP increases Impella-induced AR, particularly LV retrograde flow, resulting in reduced effective circulatory support. Strict afterload management may be essential to maximize the hemodynamic benefits of Impella support.