Myxedema-related cardiac tamponade diagnosed by focused cardiac ultrasound (FoCUS): a case report.

Introduction: Pericardial effusion can progress to cardiac tamponade, a life-threatening condition in which clinical findings are often nonspecific and a complete Beck's triad is frequently absent. Focused cardiac ultrasound (FoCUS) provides rapid bedside recognition of tamponade physiology and can expedite definitive management. This case highlights its pragmatic value for promptly identifying tamponade in a rare endocrine etiology-severe hypothyroidism (myxedema)-particularly in resource-limited settings. Case presentation: A 62-year-old man with a 6-month history of progressive lower-limb edema and exertional dyspnea deteriorated to dyspnea at rest and generalized anasarca. Examination showed myxedematous features, jugular venous distension, and muffled heart sounds. Bedside FoCUS demonstrated a massive circumferential pericardial effusion (∼28 mm in diastole) with right-atrial systolic and right-ventricular diastolic collapse, consistent with cardiac tamponade. Emergency pericardiocentesis drained 1,200 mL of serous fluid with immediate clinical improvement. Chest radiography obtained before drainage showed a "water-bottle" cardiac silhouette, and pericardial fluid studies were negative for infection and malignancy. Thyroid testing confirmed severe primary hypothyroidism (TSH 225 mIU/L; free T4 < 0.07 ng/dL). The patient was treated with monitored levothyroxine and had no recurrence of pericardial effusion on follow-up. Conclusions: Severe hypothyroidism is an uncommon but clinically important cause of cardiac tamponade. In patients with unexplained cardiomegaly or hemodynamic compromise, early FoCUS-integrated with clinical assessment and targeted biochemical testing-can rapidly confirm tamponade physiology, accelerate lifesaving pericardiocentesis, and guide timely definitive therapy. FoCUS should be incorporated into routine emergency and critical-care workflows as an extension of the physical examination.