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

Figures

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  Figure 1. Non-invasive left ventricular pressure estimation and myocardial work calculations. Panels A and B: Schematic illustration depicting transition from a standardized reference curve (blue) to an estimated individualized left ventricular pressure waveform trace (red). Panel C: Myocardial work index, represented by the area of the pressure-strain loop and related indices.

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  Figure 2. Constructing a pressure-volume loop. The upper panel: An individual volume-time trace measured with 3D-echocardiography, along simultaneously measured left ventricular pressure (LVP) (red) and non-invasive estimation of LVP (blue). The lower panel: Synchronized integration of pressures and volumes generates individual pressure-volume loops for direct same-beat comparison.

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  Figure 3. Schematic presentation of non-invasive pressure-volume analysis. Panel A: Cardiac cycle phases, valvular events, and Stroke Volume (SV) are illustrated on the pressure-volume (PV) loop, with the enclosed area representing Stroke Work (SW). Panel B: Ventricular contractility is expressed by the end-systolic elastance (Ees), the slope of the end-systolic pressure-volume relationship (ESPVR), and the one-beat contractility index ESP/EDV. The ESPVR line connects the point of end-systolic pressure (ESP) on the loop and the volume axis at an intercept (V0) where pressure equals to zero. V0 should ideally be found from multiple loops during preload constriction, but in our one-beat approach it is set to the origin. A leftward and upward shift of the ESPVR line enhances end-systolic elastance and the ESP/EDV ratio, reflecting an increase in contractility. The interaction between ventricular contractility and the arterial system, known as ventriculo-arterial coupling, is represented by the ratio of arterial elastance to end-systolic elastance. Arterial elastance serves as a surrogate measure of ventricular afterload, reflecting extra cardiac forces that oppose stroke volume ejection by…

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  Figure 4. Comparison of stroke work values derived from invasive vs. non-invasive LV pressure assessment. (A) Correlation and (B) agreement of stroke work, determined by the area enclosed within the pressure-volume loop, based on measured invasive and estimated left ventricular pressures. ICC, intra-class correlation coefficient.

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  Figure 5. Correlation and agreement of metrics derived from the pressure-volume analysis based on invasive measurements and non-invasive estimates of LV pressures. ICC, intra-class correlation coefficient.

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  Figure 6. Ventricular function before and after valve replacement. Baseline ventricular function at the time of admission for valve replacement (blue dots) and at follow-up after valve replacement (red dots). The left panel of each graph depicts trend of change, and the right panel the individual and mean differences. (A) Ejection Fraction with 2D-echocardiography. (B) Global Longitudinal Strain (GLS). (C) Global Work Index (GWI). (D) Stroke Work. (E) Ventricular Efficiency. (F) Potential Energy.

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  Figure 7. Evaluation of ventricular function in a study patient using conventional and novel echocardiographic parameters before and after valve replacement. EF, ejection fraction; EDV, end- diastolic volume; ESV, end-systolic volume; SV, stroke volume; GLS, global longitudinal strain; GWI, global work index; GWW, global wasted work; GCW, global constructive work; GWE, global work efficiency; Ees, end-systolic elastance; Ea, end-arterial elastance; VE, ventricular efficiency; VAC, ventriculo-arterial coupling; PVA, pressure-volume area; PE, potential energy.