Experimental Studies on Nd : YAG Laser Ablation as a Treatment for Tachyarrhythmia

Laser ablation が, 従来の不整脈治療法を補強する新しい治療手段となり得るか否かを検討した。雑種成犬20頭を用い, 4極カテーテルを右大腿静脈より挿入し, His 束心電図が最大となる部位を検索した。その後右心耳より Laser probe を挿入し, 出力6W～10W, 照射時間3～5秒の Laser ablationを開始した。この方法で完全房室ブロックが作成されるまで Laser 照射を反復した。Argon laser の metal tip probe とNd : YAG laser の ceramic tip probe を用いたが, すべてに完全房室ブロックが作成され, 完全房室ブロック作成に要した平均照射量は Argon laser の224Jに対し, Nd : YAG laser では平均68.2Jと有意に少量のエネルギー量で作成された。組織学的検索では, 焼灼部は完全に coagulation necrosis に陥っていた。Nd : YAG laser の照射出力と変性域の関係を検討したところ, 出力の増加に伴い, 変性域の直径, 深度は増加し, 照射量と最大深度との間には, r=0.935 (P
Recently, a surgival procedure and catheter ablation has been employed for treatment of ventricular tachycardia, that paroxysumal supraventricular tachycardia due to atrio-ventricular nodal reentry is refractory to medical therapy. We have studied for inducing the complete A-V block with application of Argon laser and Nd : YAG laser without extracorporeal circulation. The complete A-V block was produced in all dogs. The histological findings demonstrated that the very narrow segment had been changed to the coagulation necrosis. The border lines between the surrounding tissues were clear, and the ablated lesions were completely fell into the coagulation necrosis with vacuolation. Total laser energy for inducing of the complete A-V block by Nd : YAG laser was in average of 68.2J. And, in case of Argon laser it was 224J in average. We studied the comparison of the qualitative effects of both lasers, size of the circular area of tissue surrounding the crater, that of inducing by Nd : YAG laser was almost 3times as deeper as that of argon laser when the same laser power was discharged to the ventricle. And the width of crater was almost same. We studied the relationship between the deliverd Nd : YAG laser energy and the depth and diameter of the laser induced tissue lesion. There was a closed correlation (r=0.935, p