A 34-year-old woman is being evaluated for fatigue and progressive exertional dyspnea. She goes mountain biking with friends a few times a month and recently noticed that she has to stop and rest more frequently when traveling uphill. The patient has no significant medical history and takes no medications. She occasionally drinks alcohol but does not use tobacco or illicit drugs. Her father died of a myocardial infarction at age 72. Lung auscultation is normal. An echocardiogram shows an enlarged coronary sinus. Which of the following is the most likely cause of the observed finding in this patient?

Question

A 34-year-old woman is being evaluated for fatigue and progressive exertional dyspnea.  She goes mountain biking with friends a few times a month and recently noticed that she has to stop and rest more frequently when traveling uphill.  The patient has no significant medical history and takes no medications.  She occasionally drinks alcohol but does not use tobacco or illicit drugs.  Her father died of a myocardial infarction at age 72.  Lung auscultation is normal.  An echocardiogram shows an enlarged coronary sinus.  Which of the following is the most likely cause of the observed finding in this patient?

Quizplus · Accepted Answer

Most of the venous drainage from the myocardium traverses the coronary sinus (CS), which delivers deoxygenated blood to the right atrium. The CS runs transversely in the left atrioventricular groove on the posterior aspect of the heart, and opens into the right atrium between the inferior vena cava and tricuspid valve at the CS orifice. Because the CS communicates freely with the right atrium, it will become dilated by any factor that causes dilation of the right atrium. The most common cause of coronary sinus dilation evident on echocardiography is elevated right-sided heart pressure secondary to pulmonary hypertension. CS dilation also occurs in patients with anomalous venous drainage into the CS, including persistent left superior vena cava and total anomalous pulmonary venous return. (Choice A) Aortic dissection can occur in patients with severe hypertension. Such patients might have elevated left heart pressures, but elevated right-sided heart pressures with dilation of the CS would be unlikely. (Choice B) The presence of asymptomatic coronary artery disease usually does not change the size of the CS. Long-standing left ventricular systolic dysfunction due to prior myocardial infarction and ischemic cardiomyopathy can lead to secondary pulmonary hypertension, with the possibility of CS dilation over time. (Choice C) Hypertrophic cardiomyopathy usually manifests as asymmetric septal hypertrophy with or without left ventricular outflow tract obstruction. CS dilation should not occur unless there is superimposed biventricular heart failure. (Choice D) Pericardial effusion can cause extrinsic compression of the CS. Educational objective: The coronary sinus communicates freely with the right atrium and will become dilated secondary to any factor that causes increased right atrial pressure. The most common cause is pulmonary hypertension, leading to elevated right heart pressures. __________ References: Dilation of the coronary sinus on echocardiogram: Prevalence and significance in patients with chronic pulmonary hypertension. (http://www.ncbi.nlm.nih.gov/pubmed/11174433)

A 34-Year-Old Woman Is Being Evaluated for Fatigue and Progressive