Subendocardial

Subendocardial is a term used in anatomy and cardiology to describe the region of the heart located just beneath the endocardium, the innermost lining of the heart chambers. In the ventricles, the subendocardial zone lies between the endocardium and the myocardium and forms part of the inner myocardial layers.

Anatomically, the subendocardial layer contains small arteries and capillaries that supply the inner myocardium. It is also associated with the subendocardial Purkinje network in the ventricles, which plays a role in impulse conduction. The region is particularly sensitive to reductions in blood flow.

Clinically, the subendocardial region is vulnerable to ischemia. Ischemic injury that does not extend through the full thickness of the ventricular wall is termed a subendocardial infarction, as opposed to a transmural infarction that involves the entire wall thickness. Subendocardial ischemia can cause characteristic electrocardiographic changes, such as ST-segment depression and T-wave inversion, rather than ST-segment elevation.

Diagnosis typically combines ECG findings, cardiac biomarkers, and imaging. Cardiac MRI with late gadolinium enhancement can help delineate subendocardial scarring or infarction, while coronary angiography assesses perfusion defects. Understanding the subendocardial region aids in interpreting patterns of myocardial injury and guiding management.