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Every heartbeat consists of two parts — contraction and relaxation. The contraction portion of the heartbeat is known as systole, and the relaxation portion is known as diastole. Diastolic dysfunction occurs when there is a problem with the heart's diastole, meaning that the heart does not relax properly after it contracts. This condition can lead to congestive heart failure, and is in fact, present in about 50% of patients diagnosed with that condition.
The human heart is divided into four chambers. The two upper ones are called the right and left atria, while the remaining lower two are called the right and left ventricles. In a healthy heart, electrical impulses cause the atria to contract and send blood into the ventricles. The electrical impulses should then reach the ventricles, causing them to contract and push the blood out into the lungs and body. When diastolic dysfunction is present, the ventricles do not relax as they should. This makes it harder for the atria to pass as much blood into the ventricles as is ideal. This can, in turn, cause excessive pressure to build up in the heart as well as the vessels of the lungs and heart — possibly leading to congestive heart failure, systemic congestion, or pulmonary congestion.
Common causes of diastolic dysfunction generally include cardiac ischemia, aging, obesity, and hypertension. A person's risk for developing this condition increases with age, with older women having the greatest risk. Risk can be lowered by implementing lifestyle changes, such as losing weight, giving up smoking, exercising, eating a healthy diet, and limiting alcohol consumption. In addition, it is also important that a person manage his or her hypertension, cholesterol levels, and coronary artery disease to lower his or her overall suseptibilty.
Symptoms of this problem typically include fatigue, difficulty breathing, tachycardia, distension of the jugular vein, enlarged liver, and edema. A person may be affected by diastolic dysfunction for several years before any symptoms appear, however. This presents an issue because it is generally very important that a patient receives an early diagnosis and proper treatment to prevent irreversible damage to the heart's structure and systolic dysfunction. With proper care, patients affected by diastolic dysfunction have a more favorable prognosis than those who have a systolic problem.
The preferred method of diagnosing diastolic dysfunction is cardiac catheterization, but the less invasive method of two-dimensional echocardiography with Doppler may also be used. Doctors may use radionuclide angiography as a diagnostic tool in the rare cases that echocardiography cannot be done. If diastolic dysfunction is found, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or calcium channel blockers may be prescribed to improve myocardial relaxation. Beta blockers and diuretics may also be prescribed to address other symptoms, such as tachycardia, high blood pressure, difficulty breathing, and myocardial ischemia.
What are systolic and diastolic dysfunction with the mechanism that causes it?
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