Define "NSTEMI" in terms of ECG findings.

• A. ST segment elevation with increased PR interval
• B. ST segment depression or T wave inversion without ST segment elevation
• C. Normal ECG readings with chest pain
• D. Prolonged QT interval with T wave abnormalities

Answer: (B)

NSTEMI, or Non-ST-Elevation Myocardial Infarction, is characterized by specific ECG findings, primarily the presence of ST segment depression or T wave inversion without ST segment elevation. This pattern reflects a partial thickness myocardial injury and indicates ischemia without the complete occlusion of the coronary artery that is typically associated with STEMI (ST-Elevation Myocardial Infarction).

In an NSTEMI, the heart muscle is still receiving some blood flow, but it's insufficient, leading to the aforementioned changes on the ECG. These changes arise from the electrical activity in the heart being affected by the ischemic process. It's crucial for clinicians to identify these subtle changes on the ECG, as they inform the urgency and type of treatment needed for the patient.

The other options do not accurately describe NSTEMI. For instance, ST segment elevation is typical of STEMI, while normal ECG readings do not indicate any myocardial ischemia or infarction. Prolonged QT intervals and T wave abnormalities can be seen in various other conditions but are not definitive indicators of NSTEMI. Therefore, the correct interpretation of the ECG findings of NSTEMI is crucial for appropriate clinical management.