Preload

Definition

Preload is the degree of stretch of the cardiac muscle fibers at the end of diastole, just before contraction. It is influenced by the volume of blood returning to the heart.

5 Must Know Facts For Your Next Test

1. Preload is directly related to venous return and end-diastolic volume (EDV).
2. Increased preload can enhance stroke volume according to the Frank-Starling law.
3. Conditions like heart failure can alter preload by affecting venous return and ventricular compliance.
4. Medications such as diuretics and nitrates can decrease preload by reducing blood volume or venous pressure.
5. Accurate assessment of preload can be crucial in managing patients with cardiovascular conditions.

Review Questions

• How does increasing preload affect stroke volume?
• What role do diuretics play in modifying preload?
• Why is preload an important parameter in managing heart failure?

Related terms

Afterload:

The resistance the left ventricle must overcome to circulate blood.

Stroke Volume:

The amount of blood ejected by the left ventricle in one contraction.

Frank-Starling Law:

The principle that increased end-diastolic volume increases stroke volume up to a certain limit.