If asked for the term that represents a positive deflection from the baseline, which term best fits?

• A. Segment
• B. Interval
• C. Complex
• D. Wave

Answer: (D)

In ECG terminology, a positive deflection from the baseline is called a wave. The isoelectric line is the baseline, and the rising bumps above it—the P wave, the R part of the QRS complex, and the T wave—are all waves. The other terms describe different ideas: a segment is a stretch of baseline with no deflection between waves, an interval is a measure of time from one point to another, and a complex is a grouping of deflections (like the QRS) that can include both positive and negative components. Since the question is about the deflection itself rising above baseline, the best fit is a wave.