This term marks the boundary between the end of the QRS and the beginning of the ST segment.

• A. J point
• B. P point
• C. Q point
• D. T point

Answer: (A)

Think about where ventricular depolarization ends and ventricular repolarization begins. The boundary between the end of the QRS complex and the start of the ST segment is called the J point. It marks the junction where the rapid depolarization finishes and the flat ST segment begins, which is why ST changes are assessed relative to the J point. The P wave is atrial depolarization and occurs before the QRS; the Q point and T point refer to other features that don’t define this boundary.