Left ventricular contractance: A new measure of contractile function.

Area of Science:

• Cardiovascular Physiology
• Biomechanical Engineering
• Cardiac Mechanics

Background:

• Myocardial contractility assessment is inconsistent across studies.
• A standardized, quantitative measure of cardiac mechanical work is needed.
• Myocardial active strain energy density (MASED) offers a potential solution.

Purpose of the Study:

• To define and quantify a new metric for myocardial contractility: contractance.
• To establish MASED as the method for calculating contractance.
• To demonstrate contractance's utility in diverse physiological conditions.

Main Methods:

• Utilized data from three prior experimental studies on trabecular tissue.
• Analyzed nominal stress and strain data across 18 loading scenarios.
• Calculated MASED to determine contractance values.

Main Results:

• Contractance varied significantly with preload, afterload, and inotropy.
• Observed contractance values ranged from 0 to 4.7 kJ/m³.
• MASED calculation proved feasible for quantifying myocardial work.

Conclusions:

• Contractance, quantified by MASED, provides a robust measure of myocardial contractile function.
• This metric is adaptable to various preload, afterload, and inotropic states.
• The MASED method is transferable for assessing global and regional systolic function.