Question

Orthopnoea in congestive heart failure develops due to?

• A. Reservoir function of pulmonary veins
• B. Pooling of blood in lower limb veins
• C. Pulmonary hypertension
• D. Systemic hypertension

Hint:

Lying flat shifts pooled blood centrally and the failing heart backs it up into the lungs.

Answer 1

The Correct Option is A

Step 1: Orthopnoea is the sensation of breathlessness in the recumbent (lying flat) position that is relieved by sitting up or standing. It is usually a later manifestation of heart failure than exertional dyspnoea.
Step 2: On lying down, fluid that was pooled in the splanchnic circulation and the lower-extremity veins is redistributed back into the central circulation, increasing venous return to the heart and lungs.
Step 3: In a failing heart, the left ventricle cannot accommodate this increased venous return. Blood backs up into the pulmonary veins, which act as a reservoir and become engorged.
Step 4: The resulting rise in pulmonary capillary pressure causes interstitial and alveolar congestion, reducing lung compliance and producing breathlessness on lying flat, which is relieved on sitting up as the fluid redistributes again.
Conclusion: Orthopnoea in CHF develops because of the increased venous return and the reservoir function of the pulmonary veins, so option A is correct. (Reference: Harrison, 17th edition, page 1446.)