心房心室順次ペーシングにおける房室刺激間隔と左室流入血流動態

Noninvasive evaluation of changes in stroke volume and left ventricular filling dynamics.:Produced by atrioventricular interval manipulation

　近年，心房と心室間の協調的収縮をもたらす生理的ペースメーカーが開発され，積極的に臨床応用されている。生理的ペーシングは，心室ペーシングに比較し，心房収縮により左室拡張末期容積を増大させ心拍出量の増加を促す^1〜4）。また，生理的ペーシングは，心仕事効率の面からも有利であると報告されている^5）。しかし，心房心室順次ペーシングにおいて，房室刺激間隔が血行動態に及ぼす影響については，いまだ明らかでない。本研究では，非侵襲的に心腔内血流を計測できる断層心エコー・ドプラー法を用いて，大動脈弁弁輪部および僧帽弁弁輪部の血流速を計測，これらの解析から，心房心室順次ペーシングの房室刺激間隔と1回拍出量および左室流入血流動態との関係につき検討した。

To evaluate the effects of atrioventricular pacing interval on hemodynamics, we studied the changes in stroke volume and left ventricular filling dynamics in fourteen consecutive patients with imp-lanted atrioventricular pacemakers using a Doppler echocardiographic technique. Twelve patients had sick sinus syndrome and 2 had complete atriovent-ricular block. Stroke volume was determined as the time-velocity integral of the pulsed Doppler record-ings at the aortic annulus multiplied by the area of the aortic annulus obtained by 2-dimensional echocar-diography. Left ventricular filling velocity was measured at the mitral annulus by the pulsed Dop-pler technique to provide the time-velocity integral of rapid filling (TVI-R) and that of atrial filling (TVI-A). No significant change in stroke volume was noted during the atrioventricular interval mani-pulation. TVI-R was greater with short atriovent-ricular intervals than that with the long atriovent-ricular intervals. On the contrary, TVI-A was great-er with long atrioventricular intervals than that with short atrioventricular intervals. These results suggested that there is a compensatory mechanism in the left ventricular filling dynamics to keep the stroke volume constant despite the change in the atrioventricular interval. However, in patients with high atrial filling to rapid filling ratio (A/R), the stroke volume varied with change of atrioventricular interval, suggesting that the compensatory mechani-sm was not sufficient in such patients. We conclude that Doppler echocardiography is a useful, noninva-sive technique to assess the changes in the hemody-namics produced by atrioventricular interval manipu-lation in patients with implanted atrioventricular pacemakers.