The Bottom Line: Among patients with cardiac tamponade, a minority will not have dyspnea, tachycardia, elevated jugular venous pressure, or cardiomegaly on chest radiograph. A pulsus paradoxus greater than 10 mm Hg among patients with a pericardial effusion helps distinguish those with cardiac tamponade from those without.
Reference: Roy CL, Minor MA, Brookhart MA, Choudhry NK. Does this patient with a pericardial effusion have cardiac tamponade? JAMA. 2007 Apr 25;297(16):1810-8.
Summary: Signs: Depending on the degree of hemodynamic compromise, vital signs may reveal tachycardia, hypotenstion, and tachypnea. The classic findings of tamponade were described in 1935 and are known as the Beck triad: decreasing arterial, blood pressure, increasing jugular venous pressure, and a small, quiet heart. This is seen in surgical patients; medical patients, who generally develop pericardial effusions slowly, may not exhibit any of the Beck triad findings.
Symptoms: The important symptoms include dyspnea, chest pain, or fullness. Nausea or abdominal pain from hepatic and visceral congestion or dysphagia from esophageal compression may be reported. Nonspecific symptoms such as lethargy, fever, cough, weakness, fatigue, anorexia, and palpitations also occur.
Pulsus paradoxus: Most textbooks define it as a greater than 10-mm Hg difference between initial detection of sounds on expirations and the constant presence of sounds with each heartbeat. It can be detected by palpating the radial pulse and noting an inspiratory diminution of the pulse during normal respirations, or by observing the inspiratory diminution of the peripheral pulse on an arterial catheter tracing or pulse oximeter.
Other signs: Some patients with tamponade have a pericardial rub. Patients with cardiac tamponade often have an elevated jugular venous pressure at bedside examination, but the sensitivity of this finding may be reduced by the patient’s body habitus and, theoretically, in the setting of hypovolemia.
Electrocardiogram and chest radiograph: Electrocardiogram findings indicating a large pericardial effusion include low QRS voltage, electrical alternans, atrial arrhythmias, and, if pericardial inflammation is present, ST-segment elevation and PR-segment depression. Depending on the size of the effusion, the chest radiography may be normal or may demonstrate an enlarged, globular cardiac silhouette and/or and epicardial fat stripe or “double lucency” sign on lateral views.