What characterizes a transmural myocardial infarction (MI)?

A transmural myocardial infarction (MI) is specifically characterized by its involvement of the entire thickness of the myocardium, which is the muscular middle layer of the heart wall. This type of infarction typically occurs due to a prolonged blockage of blood flow to a specific area of the heart, often caused by a blood clot in a coronary artery. When this happens, the lack of oxygen and nutrients leads to the death of myocardial cells throughout the entire thickness of the heart wall, resulting in significant damage.

This significant involvement of the entire myocardial thickness distinguishes transmural MI from other types of infarctions, such as subendocardial infarctions, which only affect the inner layer, or the epicardium, which is the outer layer. The full-thickness damage associated with a transmural MI contributes to the severity of the clinical presentation and can lead to complications such as heart failure or arrhythmias, necessitating prompt medical intervention. The assessment and management of a transmural MI are critical aspects of paramedic practice.