What defines a subendocardial infarction on an EKG?

What defines a subendocardial infarction on an EKG?

• A. An infarct that affects the entire thickness of the myocardial wall
• B. An infarct that doesn't extend through the whole thickness of the left ventricular wall
• C. An area of transmural ischemia
• D. Normal cardiac muscle activity

Answer: (B)

A subendocardial infarction is characterized by damage to the inner layer of the heart muscle, specifically affecting the subendocardial region without involving the full thickness of the myocardial wall. This type of infarction typically arises due to insufficient blood flow, often linked to coronary artery disease, where the outer myocardium remains intact while the inner layer suffers ischemic injury.

In an EKG, this type of infarction may present as changes in the ST segment, particularly showing ST depression instead of the elevation seen with transmural infarctions, which involve the entire wall thickness. The differentiation is key, as it can influence treatment decisions and predictions of recovery outcomes.