Diastolic flow refers to the movement of blood through vessels during the diastolic phase of the cardiac cycle, when the heart is relaxing between beats. The presence and characteristics of diastolic flow are important diagnostic indicators in Doppler ultrasound. In low-resistance vascular beds like the brain and kidneys, continuous forward flow is maintained throughout diastole, while in high-resistance beds like the resting limb muscles, flow may slow to zero or even briefly reverse during diastole. Changes in diastolic flow patterns can indicate disease: for example, absent or reversed diastolic flow in the umbilical artery of a fetus is a concerning sign of placental insufficiency.
Sonography Term