What is the diastolic blood pressure?

Diastolic blood pressure refers to the pressure in the arteries when the heart is at rest between beats, specifically during the phase when the heart muscle relaxes. It is represented by the lower number in a blood pressure reading.

When measuring blood pressure using a sphygmomanometer, healthcare professionals listen for specific sounds that correspond to the flow of blood through the arteries as the cuff is deflated. The last sound heard, known as the fourth Korotkoff sound, indicates the pressure in the arteries during this restful phase, which is defined as diastolic blood pressure.

The upper number in a blood pressure reading corresponds to systolic blood pressure, which measures the pressure during heart contractions. Average readings over 24 hours are typically obtained through ambulatory blood pressure monitoring but do not define diastolic pressure specifically.