USMLE Step 3 - Question 11

A 71 year old female with a history of tobacco use, diabetes mellitus, rheumatoid arthritis, breast cancer is seen by her primary care physician for a routine follow-up visit. She has been feeling generally weak. She can only walk about 1/2 block before getting short of breath and dizzy. She denies chest pain. Her blood pressure is 90/60, heart rate 90, respirations 20, and she is afebrile. Her physical examination reveals normal breath sounds and no cardiac murmurs but heart sounds are distant. Her chest x-ray is below. What is her most likely diagnosis?

Step2-Q6-PIC1

A. Pericardial effusion

B. Congestive heart failure

C. Pulmonary hypertension

D. Mitral valve stenosis

The chest x-ray shows a markedly enlarged cardiac silhouette which is consistent with a pericardial effusion. This finding has been termed "water-bottle heart". The most common cause is metastatic cancer, in our patients case, most likely breast cancer. Other causes include viral, auto-immune (rheumatoid arthritis or SLE), trauma, or fluid overload from any cause (liver failure, nephrotic syndrome, congestive heart failure). The concern is for the development of cardiac tamponade in which the pericardial pressure is elevated due to the effusion resulting in collapsing of the right atrium/ventricle (lowest pressure chambers). This decreases the cardiac output causing hpyotension, dizziness, and eventually death. Tamponade results in an elevated pulsus paradoxus (greater than 12 mmHg). The only treatment is pericardiocentesis.

Congestive heart failure would show vascular redistribution and pleural effusions on chest x-ray. Also, out patient does not have any known heart disease. Pulmonary hypertension should reveal enlarged pulmonary arteries, a large right ventricle with otherwise normal appearing heart and lungs. Mitral stenosis would show a large left atrium on chest x-ray due to markedly elevated left atrial pressures.