Type I myocardial rupture is an abrupt slit-like tear that generally occurs within 24 hours of an acute myocardial infarction. Type II is an erosion of the infarcted myocardium, which is suggestive of a slow tear of the dead myocardium. Type II ruptures typically occur more than 24 hours after the infarction occurred. Type III ruptures are characterized by early aneurysm formation and subsequent rupture of the aneurysm.Another method for classifying myocardial ruptures is by the anatomical portion of the heart that has ruptured. By far the most dramatic is rupture of the free wall of the left or right ventricles, as this is associated with immediate hemodynamic collapse and death secondary to acute pericardial tamponade. Rupture of the interventricular septum will cause a ventricular septal defect. Rupture of a papillary muscle will cause acute mitral regurgitation.The rupture will most often occur near the edge of the necrotic myocardium where it abuts healthy (but hyperemic) myocardium where the inflammatory response is at its greatest. Further, the rupture will occur in an area of greatest shear stress. Within the left ventricle, these areas are adjacent to both anterior and posterior papillary muscles (regardless of whether the papillary muscle is involved in the infarction).Left ventricular free wall rupture almost always results in hemopericardium (the exception being in the scenario where the patient has had prior open heart surgery and has obliterative fibrous pericardial adhesions; these would prevent egress of blood) and pericardial tamponade.
However, the decrease in the incidence of myocardial rupture is not uniform; there is a slight increase in the incidence of rupture if thrombolytic agents are used to abort a myocardial infarction. On the other hand, if primary percutaneous coronary intervention is performed to abort the infarction, the incidence of rupture is significantly lowered. The incidence of myocardial rupture if PCI is performed in the setting of an acute myocardial infarction is about 1 percent. References


== External links ==