NBRC Sleep Disorders Specialty (SDS) Practice Exam

The presence of a depressed or inverted T wave on an ECG is a key indicator of myocardial ischemia. Ischemia occurs when there is a reduced blood flow to the heart muscle, often due to coronary artery disease. This reduction in blood flow can affect the electrical activity of the heart, particularly during the repolarization phase of the cardiac cycle, which is reflected in the T wave. In a healthy heart, the T wave is typically upright, indicating proper repolarization of the ventricles. However, when ischemia is present, changes in the T wave can be observed. A depressed T wave suggests that there is impaired repolarization of the ventricles. This can be a subtle sign of ischemic changes, indicating that the heart muscle is not receiving adequate oxygen and is under stress. Inverted T waves can also signify ischemia; they are often seen in leads facing the area of ischemic injury, providing further evidence of myocardial distress. Thus, the T wave changes are closely monitored in clinical practice to assess for complications arising from myocardial ischemia. In contrast, other options such as elevated ST segments are typically more indicative of acute myocardial infarction rather than ischemia alone. A wide QRS complex can arise from various conditions but does