A transmural infarction is characterized by its involvement of the entire thickness of the cardiac muscle wall, from the epicardium down to the endocardium. This type of infarction generally occurs due to a complete blockage of a coronary artery, leading to a significant and extensive area of ischemia. In contrast, a subendocardial infarction primarily affects only the innermost layer of the heart muscle, which is the endocardium, often resulting from a situation where there is not a complete obstruction of blood flow, but rather an inadequate supply, typically due to conditions like severe hypotension or unstable coronary plaques.
This distinction highlights the difference in the layers affected by these types of infarctions. A transmural infarction indicates a more severe and broad myocardial necrosis, while a subendocardial infarction suggests a more localized and less expansive area of damage. Understanding the pathology behind these infarction types is crucial, as it influences the clinical approach to treatment and prognosis for patients experiencing these cardiac events.