洞不全症候群における心拍応答型ペースメーカーの有用性

Utility of Rate Responsive Pacemaker on Sick Sinus Syndrome

　心拍応答型ペースメーカーの植え込みを施行した洞不全症候群10例を対象とし，運動耐容能および心機能をVVIRモードとVVIにモード変更2時間後（VVI-S），1カ月後（VVI-L）とで比較し，VVIRの有用性を検討した．

　今回の検討では，8例（80％）に負荷中自発リズムを認め，AT，peak VO₂はVVI-SとVVIRモードとでは有意差を認めなかった．しかし，VVI-LではVVIRモードに比し有意に低値であった（p＜0.01）．AT，peak VO₂時の心拍出量は両モード間で有意差を認めなかった．しかし，負荷後の心拍数，心拍出量がVVIRではVVIに比し生理的に減少した．

　以上より，慢性期運動耐容能に差を認めた理由として，この負荷後の心拍数および心拍出量の変化の，末梢循環における酸素摂取能に対する長期的な影響が示唆された。

In this study of 10 patients with sick sinus syndrome, We examined the benefits of a single-chamber ventricular pacing system that utilizes a sensor to detect the QT interval and then adjusts the heart rate. Changes in exercise tolerance capacity and cardiac function were evaluated when the pacing mode was changed from rate-variable mode (VVIR) to fixed-rate mode (VVI). Anaerobic threshold (AT), peak VO₂ and cardiac output were measured in VVIR, during short-term VVI (VVI-S), which occurred two hours after the pacing mode was changed, and during long-term VVI (VVI-L), which occurred one month after the pacing mode was changed.