Electrophysiology, Boston Scientific Corp, St. Paul, MN (M.S.S., J.I.L., P.Y., I.R., A.S., J.J.H.); Department of Electrophysiology, University Leipzig - Heart Center, Germany (S.H., J.K., G.H., A.B.); and Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN (S.K.).
Circ Arrhythm Electrophysiol. 2018 Apr;11(4):e005831. doi: 10.1161/CIRCEP.117.005831.
Coupling between the ablation catheter and myocardium is critical to resistively heat tissue with radiofrequency ablation. The objective of this study was to evaluate whether a novel local impedance (LI) measurement on an ablation catheter identifies catheter-tissue coupling and is predictive of lesion formation.
LI was studied in explanted hearts (n=10 swine) and in vivo (n=10; 50-70 kg swine) using an investigational electroanatomic mapping system that measures impedance from an ablation catheter with mini-electrodes incorporated in the distal electrode (Rhythmia and IntellaNav MiFi OI, Boston Scientific). Explanted tissue was placed in a warmed (37 °C) saline bath mounted on a scale, and LI was measured 15 mm away from tissue to 5 mm of catheter-tissue compression at multiple catheter angles. Lesions were created with 31 and 50 W for 5 to 45 seconds (n=90). During in vivo evaluation of LI, measurements of myocardium (n=90) and blood pool (n=30) were guided by intracardiac ultrasound while operators were blinded to LI data. Lesions were created with 31 and 50 W for 45 seconds in the ventricles (n=72). LI of myocardium (119.7 Ω) was significantly greater than that of blood pool (67.6 Ω; <0.01). Models that incorporate LI drop (ΔLI) to predict lesion size had better performance than models that incorporate force-time integral (=0.75 versus =0.54) and generator impedance drop (=0.82 versus =0.58). Steam pops displayed a significantly higher starting LI and larger ΔLI compared with successful radiofrequency applications (<0.01).
LI recorded from miniature electrodes provides a valuable measure of catheter-tissue coupling, and ΔLI is predictive of lesion formation during radiofrequency ablation.
消融导管与心肌之间的耦合对于使用射频消融来抵抗性加热组织至关重要。本研究的目的是评估消融导管上的新型局部阻抗（LI）测量是否能识别导管-组织耦合，并预测病变形成。
使用一种新型的电解剖标测系统在离体心脏（n=10 头猪）和体内（n=10；50-70kg 猪）中研究 LI，该系统从带有微型电极的消融导管测量阻抗，微型电极集成在远端电极（Rhythmia 和 IntellaNav MiFi OI，Boston Scientific）。离体组织放置在加热（37°C）的盐水浴中，置于天平上，并在多个导管角度下，在距组织 15mm 处测量到距导管-组织 5mm 处的 LI。用 31W 和 50W 进行消融，时间为 5 至 45 秒（n=90）。在体内 LI 评估期间，操作人员对 LI 数据不知情，通过心内超声引导对心肌（n=90）和血池（n=30）进行测量。在心室中用 31W 和 50W 进行 45 秒消融（n=72）。心肌的 LI（119.7Ω）明显大于血池的 LI（67.6Ω；<0.01）。纳入 LI 下降（ΔLI）的模型预测病变大小的性能优于纳入力-时间积分（=0.75 对=0.54）和发生器阻抗下降（=0.82 对=0.58）的模型。与成功的射频应用相比，蒸汽爆发出现在 LI 显著升高和 ΔLI 更大的情况下（<0.01）。
微型电极记录的 LI 提供了导管-组织耦合的有价值的测量，ΔLI 是射频消融时病变形成的预测指标。
