Typical placement of EP catheters for EPS includes which four sites?

• A. HRA, His, CS, RV
• B. RA, RV, His, CS
• C. HRA, RA, CS, LV
• D. LV, LA, RA, CS

Answer: (A)

In an EPS, a standard four-catheter setup targets four key locations to record and pace across the conduction system. One catheter sits in the high right atrium to monitor atrial activity and timing. A separate catheter records the His bundle region, allowing you to see the His potential and assess AV conduction. The coronary sinus catheter sits in the coronary sinus to map left‑sided activation and provide pacing from that venous route. Finally, a catheter in the right ventricle records ventricular activity and is used for ventricular pacing and provocation of tachycardias. This combination—HRA, His region, coronary sinus, and right ventricle—gives comprehensive coverage of the atrial, AV nodal/conduction, and ventricular components needed for EPS. Left-sided structures like the left ventricle or left atrium are only added for specific left‑sided mapping scenarios, not part of the standard four-site setup.