How long after myocardial infarction does a ventricular pseudoaneurysm develop?
Infarcted myocardial tissue undergoes a predictable sequence of histologic changes. As the tissue undergoes necrosis, it becomes mechanically weak and is prone to rupture. This most commonly occurs approximately 3 to 7 days after the infarction. Myocardial rupture most often occurs in the ventricular free wall but can also occur in the interventricular septum (causing a left-to-right shunt) or in a papillary muscle (causing mitral regurgitation). If the myocardial rupture is contained, a ventricular pseudoaneurysm forms. These pseudoaneurysms characteristically have a narrow mouth because they essentially represent rupture through a small hole in the myocardium, and they are more commonly posteriorly or inferiorly located. Myocardial pseudoaneurysms are generally considered to be unstable because they themselves may rupture
