Diastolic dysfunction is a heart condition that affects the organ’s capacity to fill with an adequate amount of blood during diastole. Diastole is the phase of the cardiac cycle when the heart relaxes following contraction or systole.
The condition is caused by stiffened ventricles that no longer dilate enough to accommodate incoming blood properly. This inadequate filling of the ventricles can lead to a back flow of blood into the atrium and eventually the lungs. This diastolic dysfunction raises the pressure gradient of blood in the pulmonary vessels, which causes fluid or transudate to leak from these vessels into the lung alveoli, causing pulmonary edema. This impairs oxygenation of blood in the lungs, causing shortness of breath and even death if the condition is not detected and treated promptly.
The abnormal stiffening of the ventricular wall and subsequent inadequate ventricular filling is referred to as diastolic dysfunction and when this leads to a build up of blood in other organs such as the lungs, diastolic heart failure is diagnosed. Factors that increase the risk of the ventricular walls becoming stiff are therefore considered risk factors for diastolic dysfunction.
Some examples of factors that can lead to this ventricular hardening include:
High blood pressure causes the heart to pump harder to push blood through the vessels of the body and this can eventually thicken the muscles of the left ventricle. This ventricular hypertrophy eventually turns into left ventricular stiffness.
Aortic stenosis is a disease in which the opening of the heart’s aortic valve is narrowed. Again, the heart has to work harder to distribute blood around the body, leading to muscle hypertrophy and eventually stiffness in the left ventricle.
After a heart attack, scar tissue often forms in areas of the muscles that were starved of oxygen. This healed tissue is stiff and less elastic than the original muscle tissue and can also give rise to ventricular dysfunction.
In long standing diabetic patients, the glycosylation of the heart muscles due to persistently high blood sugar leads to stiffening of the muscles and eventually to diastolic dysfunction.
Systolic heart failure
In systolic heart failure, failure of the heart to pump blood adequately leads to pooling of the blood in the ventricles, which then stretch and dilate to accommodate the blood. Eventually, the ventricular walls stretch enough to become non elastic, leading to diastolic dysfunction.
Reviewed by Sally Robertson, BSc