Imaging findings in cardiac tamponade with emphasis on CT.

Cardiac tamponade is a life-threatening condition that results from slow or rapid heart compression secondary to accumulation of fluid, pus, blood, gas, or tissue within the pericardial cavity. This condition can be associated with multiple causes including trauma, inflammation, scarring, or neoplastic involvement of the pericardial space among others. The main pathophysiologic event leading to tamponade is an increase in intrapericardial pressure sufficient to compress the heart with resultant hemodynamic impairment, which leads to limited cardiac inflow, decreased stroke volume, and reduced blood pressure. These events result in diminished cardiac output, which manifests clinically as a distinctive form of cardiogenic shock. Although cardiac tamponade is a clinical diagnosis, imaging studies play an important role in assessment and possible therapeutic intervention. Computed tomographic (CT) findings associated with cardiac tamponade include pericardial effusion, usually large, with distention of the superior and inferior venae cavae; reflux of contrast material into the azygos vein and inferior vena cava; deformity and compression of the cardiac chambers and other intrapericardial structures; and angulation or bowing of the interventricular septum. Familiarity with the clinical and pathophysiologic features of cardiac tamponade and correlation with the associated CT findings are essential for early and accurate diagnosis.