Catheter Ablation Procedures
Energy and lesion formation
Radiofrequency ablation heats tissue resistively near the electrode tip; lesion size grows with power, temperature, contact force, duration, tip size, and irrigation. Irrigated tips allow higher power without coagulum but reduce the temperature feedback's usefulness, so impedance drop and electrogram attenuation become the practical endpoints. Cryoablation creates a freeze–thaw lesion and is valued near the AV node and for pulmonary vein isolation with a balloon.
Common targets and endpoints
Typical atrial flutter is ablated at the cavotricuspid isthmus with the endpoint of bidirectional isthmus block. AVNRT gets slow-pathway modification, usually marked by accelerated junctional rhythm during delivery and non-inducibility afterward. AV nodal reentrant and accessory pathway ablation risk AV block; keep the ablation catheter away from the compact AV node and His. AF ablation centers on pulmonary vein isolation. Ventricular tachycardia ablation uses activation and entrainment mapping (PPI − TCL <30 ms) plus substrate modification.
Complications to anticipate
Tamponade, AV block, PV stenosis, phrenic nerve injury (right phrenic near the SVC and right PVs, especially with cryoballoons), coronary artery injury near the CS or mitral annulus, esophageal injury/atrial-esophageal fistula after posterior LA ablation, thromboembolism, and vascular access complications. Heparin with ACT monitoring is standard, and irrigated ablation mandates meticulous fluid balance.
Rule of thumb
A sudden impedance rise during RF delivery means coagulum formation - stop, withdraw, and clean the tip rather than increasing power. In the atrium, 25–30 W is a common starting point; ventricular lesions often use more.