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

## TL;DR

This paper introduces a non-invasive method to analyze heart function in aortic stenosis patients, showing it can accurately capture changes not seen with traditional tests.

## Contribution

A novel non-invasive pressure-volume analysis method is developed and validated for evaluating ventricular function in aortic stenosis.

## Key findings

- Non-invasive stroke work estimates strongly correlate with invasive measurements (r = 0.95, ICC = 0.95).
- Post-TAVR, ventricular efficiency and coupling improved, while energy consumption decreased.
- Conventional metrics like EF and GLS did not change after TAVR, unlike non-invasive pressure-volume analysis findings.

## Abstract

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.

Study design. Key Findings. Conclusion. LVP, Left ventricular
pressure; 2-3DE, two- and three-dimensional echocardiography; TAVR,
transcatheter aortic valve replacement; PVL, pressure-volume loop;
ICC, intra-class correlation coefficient.Synopsis of study design:
simultaneous measurements of invasive LVP using a micromanometer-tip
catheter and of 2DE/3DE echocardiography were performed immediately
before TAVR. Individual pressure–volume loops were generated
by combining LV volume-time traces from 3DE with invasive and
non-invasive LVP measurements. Key findings show a high correlation
and agreement between invasive and noninvasive stroke work. The
conclusion highlights assessment of myocardial function before and
after TAVR using noninvasive pressure–volume analysis. Graphs
illustrate the data and findings.

Study design. Key Findings. Conclusion. LVP, Left ventricular
pressure; 2-3DE, two- and three-dimensional echocardiography; TAVR,
transcatheter aortic valve replacement; PVL, pressure-volume loop;
ICC, intra-class correlation coefficient.