The Heart as a Dual Pump: Systemic & Pulmonary Circulation

The heart functions as two serial pumps in one organ.

Right Heart (Pulmonary Circuit)

1. Deoxygenated blood → SVC/IVC → Right Atrium.
2. Tricuspid valve → Right Ventricle.
3. Pulmonary valve → Pulmonary Artery → Lungs.
4. Gas exchange: CO₂ offloaded, O₂ loaded.

Left Heart (Systemic Circuit)

1. Oxygenated blood → Pulmonary Veins → Left Atrium.
2. Mitral valve → Left Ventricle (thickest wall).
3. Aortic valve → Aorta → Systemic arteries.
4. Capillary exchange: O₂/nutrients out, CO₂/waste in.

Key Features

• Series circuit: output of right = input of left (must match).
• Left ventricle generates 5–6× higher pressure (systemic resistance).
• Coronary arteries fill during diastole (right coronary → RV, left main → LV).
• Valves ensure unidirectional flow.

Clinical Correlation

• Right heart failure → systemic venous congestion (JVD, edema, hepatomegaly, ascites).
• Left heart failure → pulmonary congestion (dyspnea, orthopnea, crackles).
• Biventricular failure common.

The dual-pump design enables efficient separation of low-pressure pulmonary and high-pressure systemic circulations.