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the widening of the chambers of the heart between two contractions when the chambers fill with blood
of or relating to a diastole or happening during a diastole

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心臓拡張[期],心弛緩(しかん)[期]

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/06/17 07:11:56」(JST)

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Heart during ventricular diastole.

Diastole /daɪˈæstəliː/ is the period of time when the heart refills with blood after systole (contraction). Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing. The term diastole originates from the Greek word διαστολη, meaning dilation.^[1]

Inside the heart[edit]

Wiggers diagram, showing various events during diastole (duration marked at bottom).

During ventricular diastole, the pressure in the (left and right) ventricles drops from the peak that it reaches in systole. When the pressure in the left ventricle drops to below the pressure in the left atrium, the mitral valve opens, causing accumulated blood from the atrium to flow into the ventricle.

This is not a suction mechanism. Instead, the heart is refilled by the momentum of the blood still flowing from the previous systolic cycle. As the left and right atria contract during systole, the blood pressure in each atrium increases, forcing additional blood into the ventricles. This is known as atrial kick and it "hoists" the ventricular myocardium over the mass of blood contained within the chamber. 80% of the blood flows passively down to the ventricles, so the atria do not have to contract a great amount.^[2]

The ventricular filling velocity or flow into the ventricles have two main components; First an early (E) diastolic one caused by accumulation of blood in the atria during previous systole, and second, a late one created by atrial contraction (A). The E/A ratio can be used as a diagnostic measure, since it is reduced in diastolic dysfunction.^[3]

Atria and ventricles undergo diastole at the same time.

Inside the arteries[edit]

The adjective "diastolic" is used to refer to filling of the heart with blood between muscle contractions. It is used to describe the opposite portion of the cardiac cycle related to contraction. More typically it is used as one component of measurement of blood pressure. "Diastolic pressure" refers to the lowest pressure within the arterial blood stream occurring during each heart beat. The other component of blood pressure is systolic pressure, which refers to the highest arterial pressure during each heart beat.

Clinical notation[edit]

When blood pressure is stated for medical purposes, it is usually written as a seeming "ratio" of systolic to diastolic pressure; for example: 120/80 mmHg. This is not intended to be read as a ratio and for the vast majority of purposes cannot be legitimately read as a ratio. It is not a display of a numerator over a denominator but rather a medical notation used for quickly showing the two clinically significant pressures involved and cannot be reduced into lower terms.

References[edit]

^ Diastole. Merriam-Webster Online Dictionary. 24 August 2008.
^ Advanced Biology for You - Gareth Williams
^ Abdul Latif Mohamed, Jun Yong, Jamil Masiyati, Lee Lim, Sze Chec Tee. The Prevalence Of Diastolic Dysfunction In Patients With Hypertension Referred For Echocardiographic Assessment of Left Ventricular Function. Malaysian Journal of Medical Sciences, Vol. 11, No. 1, January 2004, pp. 66-74

External links[edit]

Diastole at eMedicine Dictionary

UpToDate Contents

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English Journal

A numerical investigation of blood damage in the hinge area of aortic bileaflet mechanical heart valves during the leakage phase.

Yun BM, Wu J, Simon HA, Arjunon S, Sotiropoulos F, Aidun CK, Yoganathan AP.SourceG. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
Annals of biomedical engineering.Ann Biomed Eng.2012 Jul;40(7):1468-85. Epub 2012 Jan 4.
Previous experimental and numerical blood studies have shown that high shear stress levels, long exposure times to these shear stresses, and flow recirculation promote thromboembolism. Artificial heart valves, in particular bileaflet mechanical heart valves (BMHVs), are prone to developing thromboem
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Effect of bending rigidity in a dynamic model of a polyurethane prosthetic mitral valve.

Luo XY, Griffith BE, Ma XS, Yin M, Wang TJ, Liang CL, Watton PN, Bernacca GM.SourceSchool of Mathematics and Statistics, University of Glasgow, Glasgow, UK, xiaoyu.luo@glasgow.ac.uk.
Biomechanics and modeling in mechanobiology.Biomech Model Mechanobiol.2012 Jul;11(6):815-27. Epub 2011 Oct 26.
We investigate the behaviour of a dynamic fluid-structure interaction model of a chorded polyurethane mitral valve prosthesis, focusing on the effects on valve dynamics of including descriptions of the bending stiffnesses of the valve leaflets and artificial chordae tendineae. Each of the chordae is
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Preoperative intra-aortic balloon pumping in high-risk cardiac surgery patients.

Moon C.SourceChooza Moon, MSN, RN, ACNP-BC, graduated from the Acute Care Nurse Practitioner Program at the University of Pennsylvania in August 2010. She currently is enrolled in the doctoral program in nursing at University of Wisconsin-Madison.
Dimensions of critical care nursing : DCCN.Dimens Crit Care Nurs.2012 Jul;31(4):223-7.
Intra-aortic balloon pumping increases myocardial oxygen supply and decreases myocardial oxygen demand by inflation and deflation of the balloon. This leads to increased perfusion of the coronary arteries during diastole. This technology has been used for critically ill cardiac patients for more tha
PMID 22664876