Disease-Specific Ventricular Unloading Responses to Impella Support Revealed by Three-Dimensional Pressure-Volume-Flow Landscape Analysis.

Abstract

Background: Impella support alters left ventricular pressure-volume (PV) relations, but disease-specific unloading responses across the full support range remain incompletely characterized. We developed a three-dimensional pressure-volume-flow landscape (3D-PVL) framework to quantify and compare ventricular unloading in acute myocardial infarction (AMI), dilated cardiomyopathy (DCM), and DCM with mitral regurgitation (DCM + MR).

Methods: PV loops were simulated using a closed-loop cardiovascular model at 51 Impella-flow levels from 0 to 5.0 L/min. Loop-centroid displacement and stroke work were normalized to their respective 0-L/min values, and their unscaled direction-sensitive derivatives were combined into a composite response. The response index (RI) quantified integrated response magnitude, while interior peak-response flow (Qpeak) identified the flow level of maximal incremental response among interior flow points. Pressure-volume area (PVA) provided energetic validation.

Results: Unloading trajectories differed among disease states despite baseline normalization. Integrated response magnitudes were similar across the three disease models (RI: 1.33, 1.37, and 1.35 for AMI, DCM, and DCM + MR, respectively), whereas interior Qpeak differed at 3.40, 2.90, and 2.70 L/min. DCM + MR showed a renewed response increase at high flow, with its overall maximum occurring at the 5.0-L/min boundary. PVA-based analysis preserved the higher-flow response peak in AMI (3.60 vs. 3.10 and 2.90 L/min in DCM and DCM + MR).

Conclusions: The underlying disease substrate influenced the distribution of ventricular unloading across the Impella-flow range despite similar integrated response magnitudes. The 3D-PVL framework provides quantitative descriptors of disease-specific unloading trajectories rather than clinically validated therapeutic targets.