Harvard Heart Letter

Ask the doctor: What is diastolic dysfunction?

Q. My last echocardiogram showed mild diastolic dysfunction. What does that mean?

A. Diastolic dysfunction means that your heart is having trouble relaxing between beats. This limits the amount of blood the ventricles can collect for the next heartbeat. Since each contraction pumps less blood, the heart works harder to make up the shortfall.

The ventricles can have trouble relaxing for two main reasons. Overworked heart muscle can "bulk up," much as your arm muscles would if you started lifting weights. The thicker the heart muscle, the less open space inside the ventricles that can fill with blood. It is also possible for the heart muscle to stiffen and become less flexible, which also diminishes the volume of blood that can fit inside the ventricles. Although bulking and stiffening are sometimes genetically determined, they usually stem from high blood pressure, cholesterol-clogged arteries, or narrowed heart valves. Less common conditions, such as amyloidosis, hemochromatosis, and sarcoidosis, cause protein, iron, or other substances to infiltrate and stiffen heart muscle.

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