This is a fatal complication of myocardial infarction and occurs when thinning of the left ventricular free wall occurs as a part of remodeling. A complete defect results in blood from the left ventricle filling the pericardium. This usually occurs rapidly resulting in cardiac tamponade, pulseless electrical activity (PEA) and death. Treatment is emergent surgical repair.

Right heart catheterization will show increased right heart pressures and decreased left heart pressures with inspiration. Also, the diastolic pressures are elevated and equal. Normally, the pericardium can expand as the heart fills, however with cardiac tamponade from a large pericardial effusion or constrictive pericarditis, this is not able to occur. As a person inspires, venous return is increased to the right heart and the interventricular septum bulges to the left impairing left ventricular filling, reducing left heart cardiac output and thus decreasing systemic pressure (increasing the “pulsus paradoxus”). As a person exhales, right ventricular filling decreases and the left heart fills causing the interventricular septum to bulge to the right impairing right ventricular filling. The diastolic pressures are elevated and equal since every cardiac chamber pressure influences the other considering the heart is not able to expand as mentioned above.