Cardiac tamponade is accumulation of blood in the pericardial sac of sufficient volume and pressure to impair cardiac filling. Patients typically have hypotension, muffled heart tones, and distended neck veins. Diagnosis is made based on history and physical examination and often bedside echocardiography. Treatment is immediate pericardiocentesis or pericardiotomy.
Fluid in the pericardial sac can impair cardiac filling, leading to low cardiac output and sometimes shock and death. If fluid accumulates slowly (eg, due to chronic inflammation), the pericardium can stretch to accommodate up to 2 L of fluid before cardiac output is compromised (1). However, with rapid fluid accumulation, as occurs with traumatic hemorrhage, as little as 150 mL may cause tamponade.
In trauma, the cause is more often a penetrating rather than blunt mechanism. The wound is often medial to the nipples (for anterior wounds) or the scapulae (for posterior wounds). Tamponade due to blunt trauma involves cardiac chamber rupture, which is typically fatal before patients can be brought for treatment.
General reference
1. Spodick DH. Acute cardiac tamponade. N Engl J Med. 2003;349(7):684-690. doi:10.1056/NEJMra022643
Symptoms and Signs of Cardiac Tamponade
Beck's triad was first described in patients with acute cardiac tamponade and consists of the following:
Hypotension
Muffled heart tones
Venous pressure increase (eg, neck vein distention)
However, Beck's triad has been shown to be an unreliable indicator for cardiac tamponade (1). Additionally, hypotension has multiple potential causes in trauma patients, muffled heart tones can be difficult to assess during a noisy trauma resuscitation, and neck vein distention can be absent due to hypovolemia. Pulsus paradoxus, a decrease in systolic blood pressure during inspiration of > 10 mm Hg, is also suggestive, but not easily assessed (2).
Symptoms and signs references
1. Alerhand S, Adrian RJ, Long B, et al. Pericardial tamponade: A comprehensive emergency medicine and echocardiography review. Am J Emerg Med. 2022;58:159-174. doi:10.1016/j.ajem.2022.05.001
2. Roy CL, Minor MA, Brookhart MA, et al. Does this patient with a pericardial effusion have cardiac tamponade?. JAMA. 2007;297(16):1810-1818. doi:10.1001/jama.297.16.1810
Diagnosis of Cardiac Tamponade
History and physical examination
Often bedside echocardiography
Diagnosis can be difficult. Beck's triad is considered diagnostic but may not be present or easy to recognize. In addition, tension pneumothorax also should be considered in patients with hypotension and neck vein distention, although this disorder typically causes markedly decreased breath sounds and hyperresonance on the affected hemithorax. E-FAST (Extended Focused Assessment With Sonography in Trauma) can be diagnostic and can be performed during the initial evaluation and resuscitation; it may be used for frequent reassessments especially if hypotension does not respond to volume resuscitation.
Treatment of Cardiac Tamponade
Pericardiocentesis
Pericardiotomy or creation of a pericardial window
Subxiphoid pericardiocentesis is performed in unstable patients when cardiac tamponade is suspected. Electrocardiographic monitoring during the insertion needle for ST segment elevation (indicating contact with the epicardium and the need to withdraw the needle) is performed if possible. Bedside ultrasound guidance for pericardiocentesis can sometimes be helpful. Pericardiocentesis is a temporizing measure. Removal of as little as 10 mL of blood may normalize blood pressure. However, failure to aspirate blood does not exclude the diagnosis; fresh blood in the pericardium is often clotted.
This illustration shows a procedure in which a needle and catheter are used to aspirate fluid from the pericardial space, typically under echocardiographic or fluoroscopic guidance. It is performed for therapeutic relief of pericardial tamponade or hemodynamically significant pericardial effusion, and/or for diagnostic evaluation of the etiology of the effusion (eg, cancer, infection, inflammatory disease).
Pepermpron/stock.adobe.com
Thoracotomy with pericardiotomy or establishment of a subxiphoid pericardial window are more definitive treatments, which are indicated in patients in whom the diagnosis is confirmed or strongly suspected. If adequately trained personnel are available and the patient is unstable and fails to respond to other resuscitative measures, a thoracotomy with pericardiotomy can be performed at the bedside in the emergency setting. Otherwise, the procedure is performed in the operating room by sternotomy or thoracotomy as soon as feasible.
Key Points
Cardiac tamponade is most often caused by a penetrating wound medial to the nipples (for anterior wounds) or the scapulae (for posterior wounds).
The triad of muffled heart tones, hypotension, and neck vein distention is diagnostic but not always present; in their absence, bedside echocardiography should be performed if the diagnosis is suspected.
Subxiphoid pericardiocentesis is a temporizing measure and may be falsely negative; a pericardial window or pericardiotomy is more definitive.
