Which statement best describes the spacing of a standard quadripolar catheter?

• A. Spacing refers to the three interelectrode gaps along the catheter
• B. Spacing indicates distance between patient and operator
• C. Spacing describes catheter diameter
• D. Spacing is the voltage setting

Answer: (A)

Spacing on a standard quadripolar catheter refers to the physical distance between the electrode pairs along the catheter shaft—the three interelectrode gaps from one electrode to the next. This spacing is fixed by the catheter design and is usually described in millimeters. It determines mapping resolution and pacing vectors: closer gaps give higher spatial resolution of local activation times, while wider gaps sample a broader region and can capture more distant signals. The other ideas—distance between patient and operator, catheter diameter, or a voltage setting—don’t describe spacing, since spacing is about the arrangement of the sensing contacts along the catheter itself, not external factors or electrical parameters.