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[The ventricular pressure-volume ratio, an index of left ventricular performance in man]
Insights
The end-systolic pressure-volume ratio effectively indicates changes in the heart's contractility (inotropic state). This ratio is more reliable than other measures, even when loading conditions change.
Area of Science:
- Cardiology
- Physiology
- Hemodynamics
Context:
- Assessing left ventricular function is crucial in cardiovascular medicine.
- Understanding the impact of vasoactive agents and potentiation on cardiac performance is essential.
- Previous methods for evaluating contractility have limitations under varying loading conditions.
Purpose:
- To evaluate the end-systolic pressure-volume ratio as an index of left ventricular inotropic state.
- To compare the sensitivity of the end-systolic pressure-volume ratio to loading modifications versus other contractility indices like left ventricular dp/dt max.
Summary:
- Left ventricular systolic pressure-volume diagrams were analyzed in 33 patients before and after vasoactive drug infusions (Nitroprusside, Angiotensin) and during post-extrasystolic potentiation.
- Measurements included aortic pressure, left ventricular volume, and derived indices (left ventricular dp/dt max., (dp/dt/Pt) max.).
- The end-systolic pressure-volume ratio demonstrated independence from loading alterations, unlike dp/dt max. and (dp/dt/Pt) max., indicating its utility in reflecting inotropic state.
Impact:
- The end-systolic pressure-volume ratio offers a robust measure of cardiac contractility, unaffected by changes in preload and afterload.
- This finding can refine the assessment of myocardial function in clinical settings.
- Provides a more reliable tool for evaluating the effectiveness of interventions aimed at altering cardiac contractility.
Abstract:
The left ventricular systolic pressure-volume diagram has been established before and after infusion of Nitro-prusside, Angiotensin and over post-extrasystolic potentiation on 33 patients, by the simultaneous measure of the aortic pressure and the left ventricular volume. In every case left ventricular dp/dt max. and (dp/dt/Pt) max. have been measured before and during post-extrasystolic potentiation, and in 16 cases after vasomotor therapy. The end-systolic left ventricular pressure-volume ratio appears to be independent of loading modifications--more than dp/dt max. and (dp/dt/Pt) max.--and on the opposite to be a good index of inotropic state alterations.