Left ventricle

Function

The left ventricle is the heart's pressure engine — a thick-walled (8–12 mm) cone of helically wound muscle that accelerates 70 ml of blood from rest to over 1 m/s sixty to a hundred times a minute, generating 120 mmHg systolic pressure into the aorta.

Its spiralling myocardial bands wring the chamber like a towel, ejecting 55–70% of its contents (the ejection fraction). During diastole the same muscle relaxes elastically to suck blood in — a property called lusitropy that fails early in heart failure with preserved ejection fraction. The chamber's very shape is a compromise between pressure work and volume work, tuned by evolution and remodelled by disease.

Blood supply

Left anterior descending and left circumflex coronary arteries.

Nerve supply

Left bundle branch Purkinje system; sympathetic fibres steepen its contractility.

Clinical relevance

Left heart failure

Failing ejection backs pressure into the lungs — exertional breathlessness, orthopnoea and pink frothy sputum in acute pulmonary oedema.

Left ventricular hypertrophy

Hypertension thickens the wall; supply demand mismatch of hypertrophied muscle causes ischaemia on normal coronaries.

Anterior myocardial infarction

LAD occlusion kills its anterior wall — the largest infarcts with the highest risk of aneurysm and rupture.

Related conditions

• Coronary artery disease
• Heart attack (myocardial infarction)
• Heart failure
• High blood pressure (hypertension)
• Aortic stenosis
• Hypertrophic cardiomyopathy
• Myocarditis
• Pericarditis