Quantification of Ventricular Hydraulic Output Using Pressure/Flow Analysis: A Single-Animal Proof-of-Concept Study During Dobutamine Stress

Introduction

Ventricular pressure and arterial flow are commonly evaluated separately, although their instantaneous product represents hydraulic power. This study examined whether synchronized ventricular pressure and arterial flow recordings can be used to describe ventricular pressure/flow coupling and hydraulic output at baseline and during dobutamine stress. Materials and Methods: This was a descriptive reanalysis of an acute experiment in one anesthetized 35 kg male swine. Left ventricular pressure, aortic pressure, and ascending aortic transit-time flow were acquired simultaneously at 200 Hz. Pressure/flow loops were constructed by plotting instantaneous left ventricular pressure against aortic flow. Ventricular hydraulic output power was calculated as P_LV(t)Q_Ao(t), and hydraulic energy per beat was calculated by time integration over the defined ejection interval. The ratio of integrated hydraulic energy to the pressure/time integral was reported as pressure-weighted mean flow. Repeated beats were treated as subsamples from one experimental unit; the results are therefore descriptive and no population-level inference was performed.