Left Ventricle Anatomy, Structure & Function

1. Introduction

The left ventricle (LV) is the thickest-walled chamber of the heart, responsible for pumping oxygenated blood into the systemic circulation via the aorta. Its anatomical design supports high-pressure output and efficient ejection of blood. Understanding LV anatomy is crucial for interpreting cardiac imaging, evaluating function, and managing cardiovascular diseases such as heart failure, hypertrophy, and valvular disorders.

2. Location and Orientation

The LV forms the apex of the heart and most of the anterior, lateral, and inferior surfaces.
Lies posterior to the right ventricle and to the left of the interventricular septum.
On chest X-ray, the apex points inferolaterally, approximately at the 5th intercostal space in adults.

3. Shape and General Features

Conical or bullet-shaped with a broad base (atrioventricular junction) and tapering apex.
Walls are thicker than any other cardiac chamber (6–12 mm in adults), reflecting its role in systemic circulation.
Internal surface is trabeculated, especially near the apex, due to trabeculae carneae.

4. Walls of the Left Ventricle

The LV wall can be divided into four main regions:

4.1 Anterior Wall

Lies beneath the sternum and costal cartilages.
Supplied primarily by the left anterior descending (LAD) coronary artery.
Contains part of the septum anteriorly.

4.2 Posterior Wall (Inferolateral Wall)

Forms part of the diaphragmatic surface of the heart.
Supplied by posterior descending artery (PDA), which can arise from RCA or LCx depending on dominance.

4.3 Lateral Wall

Faces the left lung.
Supplied by left circumflex artery (LCx).

4.4 Septal Wall

Interventricular septum separates LV from RV.
Muscular portion thicker than membranous portion.
Houses the bundle of His in its membranous segment, critical for cardiac conduction.

5. Surfaces of the Left Ventricle

Anterior surface: Faces the sternum, contributes to the cardiac apex.
Inferior (diaphragmatic) surface: Forms part of the inferior aspect of the heart.
Lateral surface: Adjacent to the left lung.
Septal surface: Shared with the right ventricle.

6. Left Ventricle Cavity

Endocardium: Lined by smooth endothelium with trabeculae carneae, which prevent suction during contraction.
Atrioventricular orifice: Connects LV to the left atrium via the mitral valve.
Outflow tract (aortic vestibule): Smooth-walled region leading to the aortic valve.

7. Papillary Muscles & Chordae Tendineae

Two main papillary muscles: anterolateral and posteromedial, attached to mitral valve leaflets via chordae tendineae.
Function: Prevent mitral valve prolapse during systole.
Blood supply:
- Anterolateral: LAD & LCx
- Posteromedial: RCA or PDA

8. Coronary Blood Supply

Left anterior descending (LAD): Anterior wall and most of septum.
Left circumflex (LCx): Lateral and posterior walls.
Posterior descending artery (PDA): Inferior wall (dominance dependent).
Clinical note: LV perfusion is critical; obstruction leads to high-risk anterior or posterior myocardial infarctions.

9. Conduction System in LV

Bundle of His: Runs in the membranous septum and bifurcates into left and right bundle branches.
Left bundle branch: Divides into anterior and posterior fascicles supplying LV myocardium.
Critical for synchronous contraction and efficient ejection.

10. Physiology Related to LV Structure

Systole: LV contracts to eject blood into the aorta (stroke volume 70–100 mL at rest).
Diastole: LV relaxes and fills from left atrium (preload-dependent).
Pressure: Normal LV systolic pressure ~120 mmHg; diastolic ~5–12 mmHg.
Cardiac output: LV performance determines systemic perfusion.

11. Clinical Relevance

11.1 LV Hypertrophy

Thickened LV walls due to hypertension or valvular disease.
ECG: increased voltage QRS complexes.

11.2 LV Dysfunction

Systolic dysfunction: reduced ejection fraction (heart failure).
Diastolic dysfunction: impaired filling, preserved EF.

11.3 LV Aneurysm

Complication of MI, particularly anterior wall infarcts.

11.4 Imaging

Echocardiography: Wall thickness, ejection fraction, valve function.
Cardiac MRI/CT: Detailed anatomy, fibrosis, ischemia.
Angiography: Coronary artery evaluation.

12. Histology

Endocardium: Endothelial lining, thin connective tissue.
Myocardium: Thick muscular layer with branching myocytes, central nuclei, intercalated discs.
Epicardium: Thin connective tissue layer covering myocardium; houses coronary vessels and fat.