preload
The degree of myocardial stretch at end-diastole, reflecting venous return and ventricular filling pressure.
Full Definition
Preload refers to the initial stretching of cardiac muscle fibers prior to contraction, determined by the ventricular end-diastolic volume and pressure. It represents the amount of blood returned to the heart and the degree of ventricular filling before systole begins. Preload is a key determinant of stroke volume according to the Frank-Starling mechanism, where increased preload (up to a point) leads to increased contractile force and cardiac output. Clinically, preload can be estimated using central venous pressure, pulmonary capillary wedge pressure, or echocardiographic measurements. Preload reduction is a therapeutic target in heart failure management.
Usage
Usage note: Often discussed in conjunction with afterload and contractility as determinants of cardiac performance.
In Context
- "Diuretic therapy was initiated to reduce preload and alleviate pulmonary congestion." — heart failure management plan
- "The patient's preload was optimized using fluid resuscitation and vasodilator therapy." — hemodynamic assessment