Word parts
What it means
It depends on how much blood has filled the ventricles by the time they start to contract, and how far that blood stretches the muscle. Up to a point, more stretch gives a stronger beat. Preload goes up with more fluid in the blood vessels and down with blood loss, dehydration, or drugs such as diuretics and nitrates. It is one of the things that set cardiac outputKAR-dee-ak OWT-putThe amount of blood the heart pumps out in one minute.Full entry , with afterloadAF-ter-lohdThe resistance the heart's ventricles must push against to send blood out into the arteries.Full entry and the strength of the heart muscle.
Remember it
Preload is the load poured in before the pump squeezes.
Related terms
cardiac output
The amount of blood the heart pumps out in one minute.
central venous pressure
The blood pressure in the large vein near the heart's right atrium, measured through a central line.
fluid overload
Too much fluid in the body, in the blood vessels and the tissues.
afterload
The resistance the heart's ventricles must push against to send blood out into the arteries.