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.
Some people with diastolic dysfunction have no symptoms. Others experience shortness of breath with mild activity, such as easy walking; difficulty breathing, especially when lying down; or swollen legs and feet.
While no treatment has yet been proven to prevent diastolic dysfunction from getting worse, several clinical trials are underway. In the meantime, your best bet is to make sure you have your blood pressure under control and pay attention to other cardiovascular risk factors such as weight, smoking, and diet. If you eat a lot of salty foods, cutting back on salt may help. Your doctor may recommend that you take certain medications, depending on your cardiac risk profile and any symptoms the diastolic dysfunction may be causing.