Ventricle (heart)

In the heart, a ventricle is a one of two large and matched right and left chambers that collect and expel blood received from an atrium towards the peripheral beds within the body and lungs. The Atria (an adjacent/upper heart chamber that is smaller than a ventricle) primes the Pump. Interventricular means between two or more ventricles (for example the interventricular septum), while intraventricular means within one ventricle (for example an intraventricular block).

In a four-chambered heart, such as that in humans, there are two ventricles: the right ventricle pumps blood into the pulmonary circulation to/for the lungs, and the left ventricle pumps blood into the systemic circulation through the aorta (systemic circulation). (See Double circulatory system for details.)

Ventricles have thicker walls than atria and can withstand higher blood pressures. This is because the ventricles have to pump blood throughout the body and lungs, while the atria only have to fill the ventricles. Further, the left ventricle has thicker walls than the right because it needs to pump blood to most of the body while the right ventricle fills only the lungs.

In systole and diastole

During systole, the ventricles contract, pumping blood through the body. During diastole, the ventricles relax and fill with blood again.

Volumes

In cardiology, the performance of the ventricles are measured with several volumetric parameters, including end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV)and ejection fraction (E_f).

Measure	Typical value
end-diastolic volume (EDV)	120 ml
end-systolic volume (ESV)	50 ml
stroke volume (SV)	55 - 100 ml
ejection fraction (Ef)	58%
heart rate (HR)	72 bpm
cardiac output (CO)	4.9 L/minute

Dimensions

The heart and its performance are also commonly measured in terms of dimensions, which in this case means one-dimensional distances, usually measured in millimeters. This is not as informative as volumes, but may be much easier to estimate with e.g. M-Mode echocardiography. Optimally, it is specified with which plane the distance is measured in, e.g. the dimension of the longitudinal plane.

Dimension	Abbreviation	Definition	Normally
End-diastolic dimension	EDD	The diameter across a ventricle at the end of diastole, if not else specified then usually referring to the transverse (left-to-right) internal (luminal) distance, excluding thickness of walls, although it can also be measured as the external distance.
Left ventricular end-diastolic dimension	LVEDD or sometimes LVDD	The end-diastolic dimension of the left ventricle.	48 mm
Right ventricular end-diastolic dimension	RVEDD or sometimes RVDD	The end-diastolic dimension of the right ventricle.
End-systolic dimension	ESD	ESD is similar to the end-diastolic dimension, but is measured at the end of systole (after the ventricles have pumped out blood) rather than at the end of diastole.
Left ventricular end-systolic dimension	LVESD or sometimes LVSD	The end-systolic dimension of the left ventricle.
Right ventricular end-systolic dimension	RVESD or sometimes RVSD	The end-systolic dimension of the right ventricle.
Interventricular septal end diastolic dimension	IVSd	The thickness of the interventricular septum.	8.3 mm
Left ventricular end diastolic posterior wall dimension	LVPWd	The thickness of the posterior left ventricular wall.	8.3 mm

Fractional shortening (FS) is the fraction of any diastolic dimension that is lost in systole. When referring to endocardial luminal distances, it is EDD minus ESD divided by EDD (times 100 when measured in percentage). Normal values may differ somewhat dependent on which anatomical plane is used to measure the distances, but 30 to 42% is considered normal with 26 to 30% representing a mild decrease in function. Midwall fractional shortening may also be used to measure diastolic/systolic changes for inter-ventricular septal dimensions and posterior wall dimensions. However, both endocardial and midwall fractional shortening are dependent on myocardial wall thickness, and thereby dependent on long-axis function. By comparison, a measure of short-axis function termed epicardial volume change (EVC) is independent of myocardial wall thickness and represents isolated short-axis function.

See also

• Atrium (heart)

References

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