diastole

(noun)

The relaxation and dilation of the heart chambers between contractions, during which they fill with blood.

Related Terms

Examples of diastole in the following topics:

  • Measuring Blood Pressure

    • Measurement of blood pressure includes systolic pressure during cardiac contraction and diastolic pressure during cardiac relaxation.
    • It is recorded as two readings: the systolic blood pressure (the top number) occurs during cardiac contraction, and the diastolic blood pressure or resting pressure (the bottom number), occurs between heartbeats when the heart is not actively contracting.
    • A normal blood pressure is about 120 mmHg systolic over 80 mmHg diastolic.
    • Hypertensive: 140 mmHg and above systolic and 90 mmHg and above diastolic.
    • A blood pressure cuff and associated monitor used for determining systolic and diastolic pressures within an artery.

  • Cardiac Cycle

    • Every single heartbeat includes three major stages: atrial systole, ventricular systole, and complete cardiac diastole.
    • Complete cardiac diastole occurs after systole.
    • Thus, there are two types of measurable blood pressure: systolic during contraction and diastolic during relaxation.
    • Systolic blood pressure is always higher than diastolic blood pressure, generally presented as a ratio in which systolic blood pressure is over diastolic blood pressure.
    • For example, 115/75 mmHg would indicated a systolic blood pressure of 115 mmHg and a diastolic blood pressure or 75 mmHG.

  • Introduction to Blood Pressure

    • Two mechanisms take place in the heart: diastole and systole.
    • Diastole is the relaxation of the chambers of the heart and systole is the contraction of the heart chambers.
    • Systolic pressure is thus the pressure that your heart emits when blood is forced out of the heart and diastolic pressure is the pressure exerted when the heart is relaxed.
    • During each heartbeat, blood pressure varies between a maximum (systolic) and a minimum (diastolic) pressure.

  • Hypertension

    • Hypertension is elevated blood pressure, clinically defined as at or greater than 140/90 (systolic/diastolic) mm/Hg.
    • Blood pressure involves two measurements, systolic and diastolic, which depend on whether the heart muscle is contracting (systole) or relaxed between beats (diastole).
    • Normal blood pressure at rest is within the range of 100-140mmHg systolic (top reading) and 60-90mmHg diastolic (bottom reading).

  • Arterial Blood Pressure

    • A person's blood pressure is usually expressed in terms of the systolic pressure over diastolic pressure and is measured in millimeters of mercury (mmHg), for example 140/90.
    • In the past, most attention was paid to diastolic pressure, but now we know that both high systolic pressure and high pulse pressure (the numerical difference between systolic and diastolic pressures) are also risk factors for disease.
    • In some cases, a decrease in excessive diastolic pressure can actually increase risk, probably due to the increased difference between systolic and diastolic pressures.
    • If systolic blood pressure is elevated (>140) with a normal diastolic blood pressure (<90), it is called "isolated systolic hypertension" and may present a health concern.

  • Checking Circulation

    • For each heartbeat, blood pressure varies between systolic and diastolic pressures.
    • Diastolic pressure is minimum pressure in the arteries, which occurs near the beginning of the cardiac cycle when the ventricles are filled with blood.
    • An example of normal measured values for a resting, healthy adult human is 120 mmHg systolic and 80 mmHg diastolic.
    • The cuff pressure is further released until no sound can be heard (fifth Korotkoff sound), at the diastolic arterial pressure.

  • Heart Failure

    • This modality uses ultrasound to determine the stroke volume (SV, the amount of blood in the heart that exits the ventricles with each beat), the end-diastolic volume (EDV, the total amount of blood at the end of diastole), and the SV in proportion to the EDV, a value known as the ejection fraction (EF).

  • Operation of Atrioventricular Valves

    • Atrial systole (contraction) increases the pressure in the atria, while ventricular diastole (relaxation) decreases the pressure in the ventricle, causing pressure-induced flow of blood across the valve.
    • Blood passes through the tricuspid valve the same as it does through the bicuspid valve, based on a pressure gradient from high pressure to low pressure during systole and diastole.

  • Artery Function

    • Arterial pressure varies between the peak pressure during heart contraction, called the systolic pressure, and the minimum or diastolic pressure between contractions, when the heart expands and refills.

  • Heart Circulation

    • In diastole, the ventricular myocardium contracts, lowering the intraventricular pressure and allowing the subendocardial vessels to become open again.
    • Due to the high pressures generated in the ventricular myocardium during systole, most myocardial tissue perfusion occurs during diastole.