Left ventricle
Ventriculus sinister
Also known as: LV
The left ventricle is the thick-walled main pumping chamber. It receives blood through the mitral valve, ejects it at high pressure through the aortic valve into the systemic circulation, and forms the apex of the heart.
Overview
Shape and wall. The left ventricle is conical and circular in cross-section. Its wall is 8–12 mm thick, two to three times thicker than the right ventricle's, because it must generate systemic pressures of about 120 mmHg. A fine mesh of trabeculae carneae lines its inner surface. Functionally, the interventricular septum belongs to the left ventricle.
Papillary muscles. Two large papillary muscles, the anterolateral and the posteromedial, each send chordae to both cusps of the mitral valve.
Inflow and outflow. Blood enters through the mitral orifice and leaves through the smooth-walled aortic vestibule below the aortic valve. Only the anterior mitral leaflet separates inflow from outflow. That leaflet is fibrously continuous with the aortic valve (the aortomitral continuity).
External surfaces. The left ventricle forms the apex, the left border of the heart, most of the left pulmonary surface and most of the diaphragmatic surface.
Contraction. During ejection the ventricle shortens lengthwise (the base moves toward the apex), thickens and twists. Viewed from the apex, the base rotates clockwise and the apex anticlockwise.
Volumes. At rest, end-diastolic volume is about 120 mL and end-systolic volume about 50 mL. That gives a stroke volume of about 70 mL and an ejection fraction of about 55–70%.
- Location
Left, posterior and inferior part of the heart. It forms the apex (left 5th intercostal space) and the left border.
Parts & subdivisions
- Trabeculae carneaeFine, dense muscular ridges, most prominent toward the apex.
- Has a dual blood supply (LAD diagonals and circumflex marginals), so it rarely ruptures.
- Usually supplied only by the posterior interventricular artery, so it is more vulnerable in inferior MI.
- Smooth outflow tract beneath the aortic valve.
- Inlet from the left atrium.
Anatomy
- Arterial supply
LAD: anterior wall, apex and anterior two-thirds of the septum. Circumflex: lateral and posterolateral wall. Posterior interventricular artery (usually from the RCA): inferior wall and posterior third of the septum.
Function
- Generates systemic arterial pressure and ejects the stroke volume into the aorta.
- Relaxes actively in early diastole, sucking blood in from the left atrium.
- Releases BNP when its wall is stretched, which makes BNP a marker of heart failure.
- Physiology
Left ventricular pressure is about 100–140 mmHg in systole and 3–12 mmHg at end-diastole. Its function is summarised by the pressure–volume loop. The loop's width is the stroke volume and its area is the stroke work. The slope of the end-systolic pressure–volume relationship indexes contractility.
Clinical significance
Left ventricular hypertrophy
Left ventricular hypertrophy is caused by hypertension, aortic stenosis or hypertrophic cardiomyopathy. On the ECG it may meet voltage criteria (for example Sokolow–Lyon: S wave in V1 plus R wave in V5 or V6 >35 mm), sometimes with a "strain" pattern. It strongly and independently predicts cardiovascular events.
Complications of LV infarction
Losing roughly 40% or more of the left ventricle causes heart failure and cardiogenic shock. Mechanical complications include papillary muscle rupture with acute mitral regurgitation, septal rupture, and free-wall rupture with tamponade. Later, a left ventricular aneurysm can form, often containing an apical mural thrombus.
Compiled from standard anatomy and physiology references — see the Cardiovascular System sources. For education only; not medical advice.