A 32-year-old woman comes to the emergency department with lightheadedness and shortness of breath, which started while shopping at a supermarket. During the last 6 months, she had increasing shortness of breath and had to adjust her daily activities. The patient has no other medical problems and does not use tobacco, alcohol, or illicit drugs. There is no family history of heart disease, stroke, or blood clots. Her BMI is 25 kg/m². After initial assessment, the patient reports that she feels "fine," refuses further evaluation, and insists on being discharged. She dies a month later. At autopsy, her heart has the following appearance (RV, right ventricle; LV, left ventricle): Which of the following is the most likely diagnosis?

Question

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Autopsy reveals significant thickening of the right ventricular free wall (almost 2 cm in thickness; normal: 3-4 mm) compared to the left ventricle. This finding of severe right ventricular hypertrophy in a young woman with progressive dyspnea and sudden death is suggestive of pulmonary arterial hypertension (PAH). Pulmonary hypertension can be caused by a number of conditions, including chronic lung disease and left heart failure. Pulmonary hypertension due to primary processes affecting the lung vasculature is referred to as PAH, a condition that most often affects women ages 20-40. PAH is characterized by intimal hyperplasia and fibrosis, medial hypertrophy, and formation of capillary tufts. Long-standing pulmonary hypertension eventually leads to hypertrophy and/or dilation of the right ventricle (cor pulmonale). Patients typically present with progressive dyspnea, exertional angina, or syncope. As PAH progresses, signs of right-sided heart failure (eg, hepatomegaly, ascites, peripheral edema) can become prominent. The most common cause of death in patients with PAH is right heart failure with circulatory collapse and respiratory failure. (Choices A and C) Aortic stenosis and essential hypertension cause left ventricular wall thickening and hypertrophy, not right ventricular hypertrophy. (Choice B) Dilated cardiomyopathy typically increases the size of one or both ventricular chambers. This patient's ventricular cavities are small and normal in size, not enlarged. Moreover, the left ventricle is relatively normal in shape (elliptical, with a long axis approximately twice that of lateral short axis dimensions), which is not the case with left ventricular dilation. (Choice D) Myocardial infarctions occur more frequently in older patients (age >65). Morphological changes in the myocardium include an area of reddish-blue discoloration that evolves into a yellow-tan discrete infarct with eventual formation of a white scar. (Choice F) Wolff-Parkinson-White (WPW) syndrome should be suspected in any case of sudden cardiac death in an otherwise healthy young individual. WPW syndrome is an electrophysiological abnormality of atrioventricular (AV) node conduction that is discernible on histology as small accessory AV impulse conduction pathway(s) anatomically separate from the AV node. There are no consistent gross morphological changes to the ventricles. Educational objective: Pulmonary hypertension should be suspected in young and otherwise healthy patients with fatigue, progressive dyspnea, atypical chest pain, or unexplained syncope. Long-standing pulmonary hypertension leads to hypertrophy and/or dilation of the right ventricle (cor pulmonale). __________ References: Management of pulmonary arterial hypertension. (http://www.ncbi.nlm.nih.gov/pubmed/25953750)

A 32-Year-Old Woman Comes to the Emergency Department with Lightheadedness