Optimization of Hybrid Hemodynamics from Mechanical Support Devices in Cardiogenic Shock

Abstract

Cardiovascular mechanical circulatory support (MCS) offers the promise of forward blood flow maintenance and distal tissue perfusion without taxing the failing heart. However, there are no firm determinants of device initiation and titration, and demonstration of definitive clinical benefit remains elusive. In part this is due to limited understanding of pathophysiologic interplay and impact.

We hypothesized that MCS use cannot be optimized without appreciation of its coupling with aortic dynamics – extending the concept of ventriculo:vascular coupling in native circulation to machine-augmented support. In both controlled porcine studies and a mock cardiovascular flow-loop with material properties, pressures, and flows that match human conditions, we examined the relative impact of the following MCS devices, alone and in combination: arterial unloading in the form of aortic counterpulsation; ventricular unloading and decoupling in the form of transvalvular impeller pump; and cardiopulmonary bypass in the form of extracorporeal membrane oxygenation.

This coupling paradigm allowed us to generate heatmaps of multiple hemodynamic metrics that define the shock and MCS-supported states and a framework by which to appreciate MCS with adjunctive pharmacologic and mixed mechanical modalities. Indeed, optimum support was defined by the balance of these metrics which can best be reduced to matching of ventricular load with vascular compliance for optimization of ‘Hybrid Flows’ – flow patterns that emerged as the cumulative sum of native heart and MCS contributions.

Translation of this work to the clinic could better inform MCS initiation, titration, and weaning and contribute to improving outcomes for cardiac failure and shock.