[The characteristic flow of the superior vena cava in cardiac tamponade: a case report].

A case of cardiac tamponade showing the characteristic flow pattern in the superior vena cava is reported. An 80-year-old man was admitted to our hospital complaining of anorexia and general fatigue. We observed a paradoxical pulse of 25 mmHg, dilatation of the jugular vein, and marked cardiomegaly on chest radiography. A two-dimensional echocardiogram demonstrated a massive pericardial effusion and collapse of the right atrial and right ventricular walls. On the basis of his echocardiograms and clinical signs, we diagnosed his condition as cardiac tamponade. Pulsed Doppler echocardiograms showed two-peaked flow in the superior vena cava in systole. To assess the diagnostic significance of this characteristic flow pattern, the superior vena cava flow was recorded simultaneously with the intrapericardial pressure and the right atrial pressure. The intrapericardial pressure was higher than the right atrial pressure in early systole. After pericardial drainage, these pressures became reversed and the two-peaked flow disappeared. The two-peaked flow is attributed to collapse of the right atrial wall caused by the higher intrapericardial pressure than the right atrial pressure. The superior vena cava flow represents the right heart filling dynamics in cardiac tamponade.