QMODE+アブレーションモード：最適なパラメータ設定とインピーダンス適応戦略

A new catheter (the QDOT-MICRO catheter) is used for high-power short duration (vHPSD) ablation.

This study aimed to optimize lesion formation in QMODE+ ablation (using QDOT-MICRO catheter) by clarifying effects of key parameters and developing impedance-adapted strategies.

Radio frequency (RF) ablation was performed on excised porcine myocardium with QDOT-MICRO catheter under QMODE+ ablation mode. Parameters included contact force (CF), power, RF duration, interlesion distance, contact angle, and impedance. The optimal parameter was determined, and adjustments for consistent lesion formation across varying impedances were investigated.

In QMODE+ ablation mode, lesion size (surface width and depth) increased with higher CF, longer RF duration, and greater power, but decreased as impedance elevated. However, lesions became smaller when CF exceeded 25 g, due to rapid temperature drops from the QMODE+ temperature control system. Perpendicular contact resulted in greater lesion depth compared to parallel contact. An interlesion distance of 5 mm was used as an experimentally evaluated reference condition and produced continuous lesions without excessive overlap. For impedance adjustments, 80 W/3 s, 80 W/4 s, and 90 W/3 s at 90Ω under QMODE+ ablation mode produced lesions comparable to those at 120Ω; when the impedance was high at 150Ω, switching to QMODE ablation mode with AI = 400/420 achieved similar lesion characteristics comparable to those at 120Ω.

Routine QMODE+ ablation with 90 W power, 4 s RF duration, catheter CF < 25 g, 5 mm interlesion distance (reference in this ex vivo model), and perpendicular contact achieves optimal lesion formation. To ensure consistent damage across different impedances, adjust QMODE+ parameters at low impedance and switch to QMODE at high impedance. Parallel contact could be preferred at fragile sites or under low impedance to reduce lesion depth and avoid over-damage.