INTRODUCTION AND EPIDEMIOLOGY
Cardiac tamponade is a rare condition in daily ED practice but in need of recognition. If a pericardial effusion compromises hemodynamics, pericardiocentesis is lifesaving. Blood or fluid filling the pericardial space can cause tamponade, with the latter dictated by the pace and volume of either material accruing. The cause of cardiac tamponade may be determined by fluid analysis after pericardiocentesis (Table 34-1).1-4 In oncology patients, look carefully for this as a cause of weakness, breathing difficulty, syncope, or chest pain.
TABLE 34-1Causes of Pericardial Effusions ||Download (.pdf) TABLE 34-1 Causes of Pericardial Effusions
|Cause ||Sagrista-Sauleda et al1 (n = 322) (%) ||Corey et al2 (n = 75) (%) ||Levy et al3 (n = 204) (%) ||Kil et al4 (n = 116) (%) |
|Acute idiopathic ||20 ||7 ||48 ||— |
|Idiopathic ||16 ||7 ||— ||4 |
|Malignancy ||13 ||23 ||15 ||52 |
|Chronic ||9 ||— ||— ||— |
|Post–myocardial infarction ||8 ||— ||— ||— |
|Uremia ||6 ||12 ||2 ||7 |
|Autoimmune ||5 ||12 ||10 ||5 |
|Radiation ||— ||14 ||— ||— |
|Infection ||— ||27 ||16 ||4 |
|Hypothyroidism ||— ||— ||10 ||3 |
|Tuberculosis ||— ||— ||— ||14 |
In a small study of medical cardiac tamponade, the mean volume drained was 593 ± 313 mL; traumatic acute tamponade typically has much smaller volumes of pericardial fluid. When the primary cause was malignancy, the 1-year mortality was almost 80%.5 In Africa, up to 70% of pericardial effusions in patients with human immunodeficiency virus are caused by tuberculosis.6
Blunt cardiac rupture is rare, occurring approximately in 1 in 2400 blunt trauma patients. Of this subgroup, 89% arrive alive to the ED.7 Those who arrive alive may benefit from a bedside US examination to detect a traumatic effusion. Tamponade from trauma is best treated with a subxiphoid window procedure, though a temporizing pericardiocentesis can aid while preparing for this or definitive surgical repair.
In a South African study, the mortality rates from chest gunshot wounds and stab wounds were 81% and 15.6%, respectively.8 This comparison underlines the probability that patients with stab wounds to the heart are more likely to survive to the ED and may benefit from pericardiocentesis.
The pericardium is a fibrocollagenous sac covering the heart that contains a small amount of physiologic serous fluid. The fibrocollagenous pericardium has elastic properties and will stretch in response to increases in intrapericardial fluid. Accumulation of fluid that exceeds the stretch capacity of the pericardium precipitates hemodynamic compromise and results in pericardial tamponade.
The initial portion of the pericardial volume–pressure curve is flat, so early on, relatively large increases in volume result in comparatively small changes in intrapericardial pressure. The pericardium becomes less elastic as the slope of the curve marches upward. As fluid continues to accumulate, intrapericardial pressure ...