Diastole is the relaxation phase of the cardiac cycle, during which the heart chambers expand and fill with blood between contractions. In the ventricles, diastole begins when the aortic and pulmonic valves close and ends when the mitral and tricuspid valves close at the start of the next systole. On echocardiography, diastolic function is assessed by measuring how quickly and completely the ventricles relax and fill, using techniques like mitral inflow Doppler, tissue Doppler imaging, and pulmonary vein flow patterns. Diastolic dysfunction, where the heart has difficulty relaxing and filling properly, is an increasingly recognized cause of heart failure and is one of the most important assessments in modern echocardiography.
Sonography Term