Curriculum · Cardiovascular and Hypertension
Cardiac tamponade
What it is
Cardiac tamponade is the major complication of a rapidly accumulating pericardial effusion, and it is a clinical diagnosis. High intra-pericardial pressure decreases venous return, which decreases diastolic ventricular filling, which decreases CO; the end of it is hypotension and venous congestion. It is a form of obstructive shock, and one of the causes of cardiac arrest that can be reversed.
Causes and risk
Aortic aneurysm or postmyocardial infarction, malignancy or radiation therapy, infection (viral, tuberculosis), connective tissue disease such as SLE, and cardiovascular surgery. More generally, any cause of pericarditis can do it, especially trauma, malignancy, uremia, and proximal aortic dissection with rupture. Two of them stand out. Free wall rupture after myocardial infarction is myocardial rupture into pericardial tamponade and obstructive shock, with sudden hypotension, distant heart sounds, pulsus paradoxus and PEA arrest; it is the most dangerous complication of MI, with mortality up to 90% if untreated. Its timing separates it from the other complications of MI: free wall rupture is 5-14 days post-MI, an acute complication, where a left ventricular aneurysm is weeks to months post-MI, a chronic one. And in aortic dissection the examination looks for signs of aortic regurgitation and signs of cardiac tamponade. Tamponade develops quickly if there is free wall rupture, a recent MI or penetrating trauma; otherwise the pericardial fluid usually accumulates slowly. It must always be considered with trauma to the chest, and in patients with metastatic malignancy, pericarditis, uremia, and those on anticoagulation. In cancer it is common enough to be looked for: tamponade develops in up to 10% of all cancer patients.