cardiac function

Cardiac function is the overall measure of how well the heart is doing its one essential job: pumping enough blood to meet the body's needs. Just as you might judge a pump by whether it keeps water flowing under load, cardiologists judge the heart by whether it delivers adequate blood at rest and during exertion.

It has two complementary halves. Systolic function is how forcefully the heart squeezes to eject blood, often summarised by the ejection fraction — the proportion of blood pushed out with each beat. Diastolic function is how well the heart relaxes and fills between beats; a stiff heart that cannot fill properly can fail even if its squeeze looks normal. Good function needs both.

Cardiac function is assessed with tools like ultrasound of the heart (echocardiography), which can show wall movement and ejection fraction, alongside blood tests and the patient's symptoms. When function declines and the heart can no longer keep up with demand, the result is heart failure.