Cardiac Tamponade

Cardiac tamponade is a clinical diagnosis and is considered a medical emergency. Imaging is used to confirm the presence of a pericardial effusion; however, it should not be solely relied on to make the diagnosis of tamponade.

Etiology

Procedural complications, infection, neoplasms, or idiopathic pericarditis, postcardiotomy, autoimmune connective tissue disorders, uremia, trauma, radiation, myocardial infarction (subacute), drugs (hydralazine, procainamide, isoniazid, phenytoin, minoxidil), hypothyroidism

Pathophysiology

• Fluid accumulation in the pericardial space increases pericardial pressure. The pressure depends on the amount of fluid, the rate of accumulation, and the compliance of the pericardium.

• Tamponade develops when the pressure in the pericardial space is sufficiently high to interfere with adequate cardiac filling, resulting in a decrease in CO.

DIAGNOSIS

History

• The diagnosis of cardiac tamponade should be suspected in patients with elevated JVP, hypotension, and distant heart sounds (Beck's triad).

• Symptoms can include dyspnea, fatigue, anxiety, presyncope, chest discomfort, abdominal fullness, and lethargy.

Physical Examination

• Pulsus paradoxus refers to an abnormally large decrease in systolic blood pressure, SV, and pulse wave amplitude with inspiration.

• A normal fall in pressure is less than 10 mm Hg. A decrease in systolic pressure >10 mm Hg is one of the physical examination findings in tamponade.

• Patients are also frequently tachycardic and hypotensive.

Diagnostic Testing

• Remember: Cardiac tamponade is a clinical diagnosis that can be made based on history, physical examination, and vital signs (blood pressure, pulsus paradoxus) alone.

• ECG: low voltage (more likely with larger pericardial effusions), sinus tachycardia, electrical alternans (specific but not sensitive).

• TTE

î First-line diagnostic test to evaluate the hemodynamic significance of pericardial effusion.

î Features suggestive of a hemodynamically significant pericardial effusion:

■ Dilated, incompressible IVC.

■ Significant respiratory variation of tricuspid and mitral inflow velocities (>25% mitral, >40% tricuspid).

■ Early diastolic collapse of the right ventricle and systolic collapse of the right atrium.

TREATMENT

• Limited role for medical therapy to treat cardiac tamponade. Goal is to maintain adequate filling pressures with IV fluids. Avoid diuretics, nitrates, and any other preload-reducing medications. Avoid efforts to slow down sinus tachycardia: it compensates for a reduced SV to try to maintain adequate CO.

• Percutaneous pericardiocentesis with echocardiographic guidance can be a relatively safe and effective way to drain the pericardial fluid; the approach should be guided by location of the fluid and is usually easiest when the effusion is in anterior location.

• Creation of a pericardial window is preferred for recurring effusions, loculated effusions, or those not safely accessible percutaneously.