Topic Overview

Diastolic heart failure occurs when the lower left chamber (left ventricle) is not able to fill properly with blood during the diastolic (filling) phase. The amount of blood pumped out to the body is less than normal.

What happens to the heart?

Diastole is the phase of your heartbeat when your heart relaxes and fills with blood. Diastolic dysfunction means that your left ventricle cannot relax properly during diastole. As a result, your ventricle doesn't fill with enough blood before it pumps. If diastolic dysfunction is severe enough, it can lead to heart failure.

Diastolic heart failure happens because the left ventricle's muscle becomes too stiff or thickened. To compensate for stiff heart muscle, your heart has to increase the pressure inside the ventricle to properly fill the ventricle. Over time, this increased filling causes blood to build up inside the left atrium and eventually into the lungs, which leads to fluid congestion and the symptoms of heart failure.

Diastolic heart failure may not lower the heart's ejection fraction. Ejection fraction is a measurement of how well the heart is pumping out blood. This ejection fraction is typically lower in people who have systolic heart failure. But in diastolic heart failure, your left ventricle may pump well during systole; it is just not filling with enough blood during diastole. Your ventricle may have a normal ejection fraction, but it has less blood inside it to pump out. As a result, your ventricle pumps out less blood with each beat.

What causes it?

The most common cause of diastolic heart failure is the natural effect of aging on the heart. As you age, your heart muscle tends to stiffen, which can prevent your heart from filling with blood properly, leading to diastolic heart failure.

But there are many health problems that can impair your left ventricle's ability to fill properly with blood during diastole.