What is the spacing on a quadripolar catheter?

• A. 1-2-3
• B. 2-5-2
• C. 3-4-3
• D. 4-6-4

Answer: (B)

Quadripolar catheters are designed with four electrodes in a straight line along a short segment of the catheter. The standard spacing is 2-5-2 millimeters. This means the gap from the most distal electrode to the next is 2 mm, the gap between the middle two electrodes is 5 mm, and the gap from the third to the most proximal electrode is 2 mm. This arrangement provides a compact distal region for precise local activation timing and pacing, while the wider middle interval helps sample electrical activity over a small length of tissue without excessive signal overlap. In practice, this spacing supports accurate mapping by allowing reliable comparisons between adjacent electrode pairs.