A ventricle is one of two large chambers located toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs.

Its posterior wall is formed by the ventricular septum, which bulges into the right ventricle, so that a transverse section of the cavity presents a semilunar outline.

Its upper and left angle forms a conical pouch, the conus arteriosus, from which the pulmonary artery arises.

[citation needed] The left ventricle is longer and more conical in shape than the right, and on transverse section its concavity presents an oval or nearly circular outline.

The right ventricle is triangular in shape and extends from the tricuspid valve in the right atrium to near the apex of the heart.

[5] The moderator band connects from the base of the anterior papillary muscle to the ventricular septum.

The left ventricular muscle must relax and contract quickly and be able to increase or lower its pumping capacity under the control of the nervous system.

Likewise in the systolic phase, the left ventricle must contract rapidly and forcibly to pump this blood into the aorta, overcoming the much higher aortic pressure.

The extra pressure exerted is also needed to stretch the aorta and other arteries to accommodate the increase in blood volume.

Maximum capacity pumping volume extends from ~25 liters/min for non-athletes to as high as ~45 liters/min for Olympic level athletes.

This is not as informative as volumes but may be much easier to estimate with (e.g., M-Mode echocardiography[17] or with sonomicrometry, which is mostly used for animal model research).

[citation needed] The most severe form of arrhythmia is ventricular fibrillation which is the most common cause of cardiac arrest and subsequent sudden death.