© 1999 by European Society of Cardiology
Relationship between atrioventricular delay, QT interval and cardiac function in patients with implanted DDD pacemakers
Second Department of Internal Medicine, Yokohama City University Urafune Hospital Yokohama, Japan
QT interval may change when cardiac function is improved by optimizing the atrioventricular the (AV) delay. The relationship between AV delay, QT interval and cardiac function in patients with implanted DDD pacemakers was studied in 12 patients (aged 71 ± 12 SD years) with complete or high degree AV block. Cardiac output (CO) was measured using a SwanGanz catheter or by continuous Doppler echocardiography. The pacing rate was fixed at 7080/min to eliminate the influence of heart rate. The AV delay was prolonged stepwise by 30 ms starting from 90 ms. All measurements were performed after 5 min of pacing. When the AV delay was prolonged, the CO and QT interval gradually increased and reached a peak, and then decreased. When the CO was increased from the minimum to the maximum value by optimizing the AV delay, the QT interval was significantly prolonged from 440 ± 40 to 456 ± 39 ms (P<0·002). The CO increased from 5·5 ± 2·5 to 6·0 ± 2·5 l·min1 (P<0·002) when the AV delay was changed, during which the QT interval was prolonged from the minimum to the maximum value. There was a significant positive correlation between the optimal AV delay at which CO was maximal (161 ± 33 ms) and the optimal AV delay predicted from the maximum QT interval (167 ± 29 ms, r=0·85, P<0·001). In conclusion, the optimal AV delay can be predicted from the QT interval.
Key Words: PQ interval, QT interval, DDD pacemaker, atrioventricular block, cardiac output, atrioventricular delay
Correspondence: Toshiyuki Ishikawa, MD, Second Department of Internal Medicine, Yokohama City University Urafune Hospital, 346, Urafune-cho, Minami-ku, Yokohama 2320024, Japan.
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T. Ishikawa, T. Sugano, S. Sumita, T. Nakagawa, K. Hanada, M. Kosuge, I. Kobayashi, K. Kimura, O. Tochikubo, T. Usui, et al. Optimal atrioventricular delay setting determined by evoked QT interval in patients with implanted stimulus-T-driven DDDR pacemakers Europace, January 1, 2001; 3(1): 46 - 51. [Abstract] [PDF] |
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