Left ventricle

At a glance

English

Left ventricle

Latin (TA2)

Ventriculus sinister

System

Heart

Region

Trunk

Side

Single, on the midline

About the left ventricle

The left ventricle is the main pumping chamber of the heart. It receives oxygen-rich blood from the left atrium through the mitral valve and drives it into the aorta through the aortic valve. It forms the apex, most of the left (pulmonary) surface, most of the diaphragmatic surface and only a narrow strip of the front of the heart, since the right ventricle covers most of that view.

Its cavity is long and cone-shaped, circular or oval in cross-section, and its wall is normally about three times as thick as the right ventricle's. That extra muscle reflects the much higher pressure it must generate: blood enters at low pressure from the lungs and must be pushed into an aorta at systemic pressure with every beat. Inside, most of the wall is roughened by trabeculae carneae, fine interlacing muscle ridges. Two papillary muscles, anterolateral and posteromedial, rise from the wall and send chordae tendineae to both mitral leaflets. The part of the cavity just below the aortic valve, the aortic vestibule, has smooth, mostly fibrous walls.

The anterior leaflet of the mitral valve separates the inflow from the outflow, so blood turns a sharp corner within the ventricle. The interventricular septum, its right-hand wall, bulges into the right ventricle and contracts with the left side.

In systole the ventricle shortens, thickens and twists, and pressure rises until the aortic valve opens. In diastole it must relax quickly to fill again. Its performance is measured as stroke volume and ejection fraction. Long-standing high blood pressure or aortic stenosis thickens its wall, while infarction of the territory of the left coronary artery weakens it and can lead to heart failure. Disorders of the conducting tissue in its wall can cause ventricular extra beats, ventricular tachycardia or fibrillation.

Function and supply

Function

Pumps oxygenated blood through the aortic valve into the aorta and the systemic circulation, generating the systemic arterial pressure.

Nerve supply

Sympathetic and vagal fibres from the cardiac plexus; its contraction is timed by the left bundle branch and Purkinje fibres.

Blood supply

Mainly the left coronary artery through its anterior interventricular and circumflex branches, with the inferior wall supplied by the right coronary artery in most people; veins drain to the coronary sinus.