In a patient with chronic obstructive pulmonary disease who develops acute cor pulmonale, the primary physiological mechanism leading to right ventricular failure is:

• A Hypoxic pulmonary vasoconstriction increasing pulmonary vascular resistance ✓
• B Venous return obstruction from elevated diaphragm
• C Polycythaemia increasing blood viscosity and afterload
• D Acidosis directly depressing RV myocardial contractility

Explanation

Hypoxic pulmonary vasoconstriction (HPV) is the primary mechanism: alveolar hypoxia triggers smooth muscle contraction in pulmonary arterioles, raising pulmonary vascular resistance and thus RV afterload. In COPD with widespread V/Q mismatch, this HPV is generalized rather than beneficial, chronically elevating pulmonary artery pressure. Polycythaemia and acidosis contribute, but HPV is the dominant initial and ongoing mechanism.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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