Transthoracic M-mode Echocardiography Demonstrating Cardiac Tamponade

A 67-year-old man presented to the emergency department for two weeks of progressive shortness of breath with orthopnea and new-onset back pain. On admission, vital signs were normal, and physical exam was remarkable for jugular vein distention with the rest of the cardiovascular exam in normal limits. A bedside transthoracic echocardiogram showed a large circumferential pericardial effusion with M-mode analysis revealed diastolic collapse of the right ventricle (RV) and > 40% tricuspid inflow respiratory variation in Doppler. Emergency pericardiocentesis yielded 800 cm3 of yellow-colored fluid. Subsequently, the patient underwent lymph node biopsy showing tumor cells consistent with squamous cell carcinoma of unknown origin. This case highlights the use of bedside echocardiogram and M-mode imaging for the diagnosis of cardiac tamponade.