Shock, and even death, can occur. The diagnosis is clinched with an echocardiogram, that shows not only the fluid in the pericardial sac, but also the constriction of the heart chambers caused by that fluid. Chronic pericarditis occurs when the pericardial inflammation does not resolve within a few weeks. It can be associated with all the symptoms of acute pericarditis, and in addition is often associated with particularly large pericardial effusions. Because when pericarditis is chronic the pericardial lining has a chance to stretch itself out and become relatively flaccid, severe tamponade often does not occur even when massive pericardial effusions are present.
Constrictive pericarditis is one possible outcome of chronic pericarditis.
Pericardial constriction occurs when a chronically inflamed pericardial sac becomes adherent to the heart muscle, squeezing it and limiting the heart s ability to fill with blood. The symptoms are the same as with tamponade, but usually have a much more gradual onset. Most often a careful cardiac catheterization needs to be performed, paying particular attention to the pressures in the cardiac chambers during the interval between heartbeats. A CT or MRI scan can also help to diagnose chronic or constrictive pericarditis, by showing the thickening of the pericardial lining associated with these conditions. In general, anticoagulation is avoided, since bleeding into the pericardial sac can cause acute tamponade.