A 44 year old man presents with chest discomfort and dyspnea for 2 weeks; these symptoms have markedly worsened over the last 4 days. He is otherwise asymptomatic, with no history of paroxysmal nocturnal dyspnea or orthopnea. His medical, surgical, and family histories are unremarkable. He only drinks socially, and has never smoked before. An urgent 12-lead ECG reveals a rate of 106 bpm, with a regular rhythm. All leads show low voltage QRS complexes with electrical alternans.
There is a pericardial effusion measuring ~22 mm. All cardiac chambers appear small. Collapse of the right atrium is noted in more than one-third of the cardiac cycle, while end-diastolic collapse of the right ventricle is also present. The vena cavae are plethoric and dilated.
You realize that CT imaging of the thorax is probably not appropriate right now!
You realize that cardiovascular magnetic resonance imaging (MRI) is probably not a good idea right now!