Preload
The degree of ventricular stretch at the end of diastole, determined by venous return and ventricular compliance. Affects cardiac output via the Frank-Starling mechanism.
Full Definition
Preload refers to the initial stretching of cardiac muscle fibers prior to contraction, typically measured as the end-diastolic volume or pressure in the ventricle. It represents the amount of blood returned to the ventricle during diastole and is influenced by factors such as venous return, blood volume, ventricular compliance, and atrial contraction. According to the Frank-Starling law of the heart, increased preload generally results in increased stroke volume up to a physiological limit. Understanding preload is crucial for managing heart failure, as excessive preload can lead to pulmonary or systemic congestion.
Usage
Usage note: Distinguish clearly from afterload in clinical documentation.
In Context
- "Diuretics were administered to reduce preload and alleviate the patient's pulmonary congestion." — Heart failure management plan
- "The Swan-Ganz catheter measurements indicated elevated preload with a pulmonary capillary wedge pressure of 25 mmHg." — Hemodynamic assessment report