The most common cause of acute cor pulmonale is:
**Core Concept**
Acute cor pulmonale refers to a sudden onset of right ventricular failure, often due to a precipitating event affecting the pulmonary vasculature. This condition arises when the right ventricle is unable to pump blood effectively into the pulmonary circulation, leading to pulmonary congestion and potentially life-threatening complications.
**Why the Correct Answer is Right**
The most common cause of acute cor pulmonale is a pulmonary embolism (PE). A PE occurs when a blood clot lodges in one of the pulmonary arteries, obstructing blood flow to the lungs. This sudden blockage increases the pressure in the pulmonary vasculature, leading to strain on the right ventricle. The right ventricle is unable to compensate for the increased pressure, resulting in acute cor pulmonale. The pathophysiology involves the activation of the sympathetic nervous system, release of vasoconstrictors, and subsequent increase in pulmonary vascular resistance.
**Why Each Wrong Option is Incorrect**
**Option A:** While pneumonia can lead to cor pulmonale, it is not the most common cause of acute cor pulmonale. Pneumonia typically results in a more gradual increase in pulmonary pressure and is less likely to cause sudden right ventricular failure compared to a pulmonary embolism.
**Option B:** Asthma can induce cor pulmonale, but it is not the most common cause. Asthma typically results in a more chronic increase in pulmonary pressure due to airway obstruction and inflammation.
**Option C:** Chronic obstructive pulmonary disease (COPD) can lead to cor pulmonale, but it is not the most common cause of acute cor pulmonale. COPD typically results in a more gradual increase in pulmonary pressure due to chronic airway obstruction and emphysema.
**Clinical Pearl / High-Yield Fact**
Remember that a sudden onset of dyspnea, cough, and chest pain in a patient with a history of deep vein thrombosis or recent immobilization may indicate a pulmonary embolism, which is the most common cause of acute cor pulmonale.
**Correct Answer: C. Chronic obstructive pulmonary disease (COPD)**