Ventricular Pressure-Volume Loops Obtained by 3D Real-Time Echocardiography and Mini-Pressure Wire

Introduction: Pressure-volume relations (PVR) provide vital information regarding ventricular performance and cardiac pathophysiology. Acquiring PVR by conductance catheter technology is invasive and laborious, which explains why the assessment of PVR is not used in clinical practice. Real-time 3D-echocardiography (3DE) allows nearly instantaneous capture of ventricular volume changes throughout the cardiac cycle. The aim of the study was to assess the feasibility of 3DE combined with pressure data to calculate PVR in children and adolescents.

Methods: In 31 patients with congenital heart disease (age: 3 days-22.7 years, weight: 2.75 – 80.0 kg), ventricular pressure was recorded by a mini pressure wire during routine catheterization. Simultaneously, right and left ventricular 3D datasets were acquired for calculation of volume. PVRs were generated from contemporaneous 3D volume and pressure data. Systolic myocardial elastance, ventriculo-arterial coupling, diastolic relaxation constant Tau, and end-diastolic PVR were determined using a single-beat approach.

Results: Computation of PVR was easy, feasible, reproducible, and comparable with results obtained by conductance technique in the literature. Intra- and interobserver variability were good for all measured parameters (coefficients of variation < 10%).

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Conclusions: Calculation of PVR from 3DE volume curves and simultaneous pressure data obtained by a mini pressure wire is a feasible method to assess cardiac function. Due to the tiny size of the pressure wire used, PVR can be acquired even in small neonates with congenital heart disease.