Effectiveness and Safety of High-Power Radiofrequency Ablation Guided by Ablation Index for the Treatment of Atrial Fibrillation

Figure 2

Ventricular lesions obtained with constant AI of 500 and with 50 W, 40 W, or 30 W of power output. (a) By visual inspection, increasing power was associated with larger lesion maximum diameter (green line) and deeper tissue necrosis (red line), with boundaries of tissue lesion and necrosis becoming clearer. (b–d) Lesions (green line) and necrosis (red line) generated with 30 W, 40 W, and 50 W were examined under 20× amplification; under 400× magnification at 1 mm from the ablation catheter tip in panels B1 (mainly basophilic changes of connective tissue with least myocardial cell changes and nuclear pyknosis), C1 (small number of myocardial cells with fuzzy sarcoplasm, no horizontal stripes and nuclear pyknosis), and D1 (largest number of affected myocardial cells); and under 200× magnification at 3 mm from the ablation catheter tip in panels B2 (no basophilic changes of fibrous connective tissue), C2 (basophilic changes only around cells), and D2 (basophilic changes around the blood vessels and cells).

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