Question

The most common cause of acute cor pulmonale is:

• A. Pneumonia.
• B. Pulmonary thrombo-embolism.
• C. Chronic obstructive pulmonary disease.
• D. Primary spontaneous pneumothorax.

Hint:

Acute onset plus sudden right heart strain should point straight to a large pulmonary embolus.

Answer 1

The Correct Option is B

Step 1: Understanding the Question.
Cor pulmonale means right heart strain or failure caused by a lung problem that raises pressure in the pulmonary circulation. It can develop suddenly (acute) or slowly over years (chronic), and this question asks about the acute form.

Step 2: Key Concept.
Acute cor pulmonale happens when the right ventricle is suddenly forced to pump against a sharp rise in pulmonary vascular resistance, most often because a large clot blocks the pulmonary arteries. Chronic cor pulmonale, by contrast, builds up slowly and is usually caused by long-standing lung disease like COPD.

Step 3: Detailed Explanation.
Option (1) pneumonia: severe pneumonia can strain the right heart, but this is not the leading cause of acute cor pulmonale.
Option (2) pulmonary thrombo-embolism: a large embolus suddenly blocks a major branch of the pulmonary artery, causing pulmonary artery pressure to spike within minutes to hours. The right ventricle cannot adapt that fast, so it dilates and can fail acutely, making this the most common cause.
Option (3) chronic obstructive pulmonary disease: COPD causes cor pulmonale, but the process develops over years through gradual hypoxic vasoconstriction and vascular remodeling, so it is the leading cause of chronic, not acute, cor pulmonale.
Option (4) primary spontaneous pneumothorax: this can cause acute cardiorespiratory compromise in severe cases, particularly if it becomes tension pneumothorax, but it is a much less common cause of acute cor pulmonale than pulmonary embolism.

Step 4: Final Answer.
The most common cause of acute cor pulmonale is pulmonary thrombo-embolism.
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