Non-invasive pressure-volume analysis: a novel method for evaluating ventricular function in patients with aortic...

Conventional echocardiographic measurements like ejection fraction (EF) and global longitudinal strain (GLS) evaluate left ventricular (LV) function without considering concurrent loading conditions. A more comprehensive characterization of cardiac function and energetics can be achieved through pressure-volume analysis, but its clinical application is limited by the requirement for invasive measurements. We aimed to develop a clinically accessible, non-invasive method for pressure-volume loop analysis.

We obtained simultaneous 3-dimensional echocardiograms and invasive LV pressures with micromanometer-tipped catheters during transcatheter aortic valve replacement (TAVR) for severe aortic stenosis. Volume-time traces from the echocardiograms were combined with invasive LV pressures and non-invasive pressure estimates to construct pressure-volume loops. We used echocardiograms before and after TAVR to evaluate changes in myocardial function via non-invasive pressure-volume studies.

In same-beat comparisons, stroke work calculated using non-invasive LV pressure estimations correlated well with stroke work calculated using invasive LV pressures (r = 0.95, ICC = 0.95, p < 0.0001, y = 0.90X + 1,836, mean bias -549 mmHg*mL, standard deviation 774 mmHg*mL; 95% limits of agreement: -2,006 to +967 mmHg*mL). After TAVR, stroke work fell substantially, ventricular efficiency increased, ventriculo-arterial coupling improved, and both total and resting energy consumption decreased. On the other hand, LV biplane EF and GLS remained unchanged.

This study confirms the validity and clinical accessibility of non-invasive pressure-volume loop analysis in patients with aortic stenosis. The method identified and characterized changes in myocardial energetics, function, and ventriculo-arterial interaction, that are not typically detected by conventional echocardiography. These findings highlight the potential of non-invasive pressure-volume analysis in clinical and research practice.