The syndrome of cardiac tamponade with "small" pericardial effusion

Cardiac tamponade is usually a consequence of increased pericardial pressure with accumulation of pericardial effusion. Pericardial effusion may be caused by acute pericarditis, tumor, uremia, hypothyroidism, trauma, cardiac surgery, or other inflammatory/noninflammatory conditions. In this article we describe four scenarios illustrated by case reports where a small or apparently small pericardial effusion may produce cardiac tamponade. The first scenario illustrates how a small pericardial effusion can cause clinically significant cardiac tamponade when it accumulates rapidly. The second scenario exhibits how an apparently small pericardial effusion on transthoracic echocardiogram (TTE) turned out to be a small amount of unclotted blood and an echogenic hematoma. The third scenario details how an apparently small pericardial effusion on TTE was actually a large loculated effusion in an unusual location seen only by transesophageal echocardiogram (TEE). The fourth scenario demonstrates how the combination of a large pleural effusion and a small pericardial effusion can result in cardiac tamponade. The role of echocardiography in the diagnosis and management of these scenarios is discussed here. Although many clinicians depend on the amount of pericardial effusion to suspect cardiac tamponade, it is important to suspect cardiac tamponade when patients have hemodynamic compromise regardless of the amount of pericardial effusion.