23. Advanced 3D Electroanatomical Mapping and Catheter Ablation Principles

Advanced electroanatomical mapping systems (CARTO, EnSite Precision, Rhythmia) integrate real-time catheter location with intracardiac electrograms to reconstruct 3D cardiac chambers, substrate voltage maps, and complex reentrant circuits.

1. Electroanatomical Substrate & Voltage Mapping

Bipolar Voltage Thresholds in Ventricular Mapping:
- Dense Fibrotic Scar: Bipolar voltage $< 0.5\text{ mV}$ (electrically inexcitable myocardium).
- Border Zone / Scar Isthmus: Bipolar voltage between $0.5 - 1.5\text{ mV}$ (heterogeneous channels supporting slow conduction and reentry).
- Normal Healthy Myocardium: Bipolar voltage $> 1.5\text{ mV}$.
Unipolar Voltage Mapping: Unipolar threshold $< 8.3\text{ mV}$ penetrates deeper into the myocardium to detect subepicardial and intramural scars invisible on endocardial bipolar maps (e.g. in Non-Ischemic Dilated Cardiomyopathy and ARVC).

2. Activation & Entrainment Mapping of Tachycardia Circuits

ENTRAINMENT MAPPING CRITERIA FOR REENTRY

Fixed pacing at cycle length slightly shorter than tachycardia (TCL - 20 ms).
Surface ECG shows Concealed Entrainment (identical morphology to clinical VT).
Post-Pacing Interval (PPI) minus Tachycardia Cycle Length (TCL): PPI - TCL < 30 ms ===> Catheter is INSIDE the Critical Protected Isthmus!

3. Advanced Energy Delivery Modalities

Radiofrequency (RF) Energy: Thermal resistive heating creating coagulative necrosis; irrigated-tip catheters prevent thrombus formation.
Pulsed Field Ablation (PFA): Non-thermal irreversible electroporation using high-voltage microsecond electrical fields that selectively permeabilize cardiomyocyte cell membranes while sparing adjacent phrenic nerve, esophagus, and coronary arteries.