Which catheter is used to record the LA and LV?

• A. CS catheter
• B. His catheter
• C. Right atrial catheter
• D. Endocardial catheter

Answer: (A)

The coronary sinus catheter is the best choice for recording left atrial and left ventricular activity because the coronary sinus lies in the posterior atrioventricular groove and is in close proximity to both chambers. With a multielectrode catheter in the coronary sinus, the proximal electrodes sit near the left atrial aspect at the ostium, while the distal electrodes are near the left ventricular free wall. This arrangement allows simultaneous sampling of LA and LV activation and is standard during EP studies to map left-sided conduction and to provide reference signals for pacing. In contrast, a His catheter targets the His bundle, a right atrial catheter records RA activity, and an endocardial catheter is not specifically positioned to sample LA/LV signals from the coronary sinus.