Author + information
- Received August 10, 1995
- Revision received March 4, 1996
- Accepted March 11, 1996
- Published online July 1, 1996.
- Kaoru Okishige, MD∗,
- Katsuhiro Yamashita, MD,
- Haruhiko Yoshinaga, MD,
- Kouji Azegami, MD,
- Takako Satoh, MD,
- Yoshenari Goseki, MD,
- Satoki Fujii, MD,
- Hiroshi Ohira, MD and
- Shutarou Satake, MD
- ↵∗Address for correspondence: Dr. Kaoru Okishige, Cardiac Electrophysiology Laboratory, Yokoham Red Cross Hospital, 2-85 Negishi, Naka-ku, Yokohama City, Japan
Objectives. The aim of this study was to examine the effect of ischemic preconditioning on the manner of ventricular repolarization by assessing the change in QT dispersion during coronary angioplasty.
Background. QT interval dispersion regional variations in ventricular repolarization and cardiac electrical instability. Previous studies have suggested that increased QT dispersion is associated with an increased incidence of malignant ventricular arrhythmias, whereas brief episodes of myocardial ischemia can render the heart more resistant to subsequent ischemic episodes, a phenomenon called ischemic preconditioning.
Methods. To assess the effects of ischemic preconditioning on myocardial repolarization by examining the change in QT dispersion during coronary angioplasty, we studied 47 consecutive patients (39 men and 8 women; mean age 57 ± 16 years). QT dispersion was measured after each balloon inflation during coronary angioplasty. Statistical analysis was performed by using repeated measurement of analysis of variance.
Results. There were significant differences in QT dispersion as the number of balloon inflations increased (mean ± SD 52 ± 14, 42 ± 11, 36 ± 9, 31 ± 10 and 29 ± 11 ms, respectively [p < 0.01], for the first, second, third, fourth and fifth balloon inflations). The magnitude of decrease in QT dispersion was significant in the first and second balloon inflations, then became insignificant with later inflations.
Conclusions. These data indicate that the gradual decrease in OT dispersion provoked by coronary artery occlusion and reperfusion during coronary angioplasty may be associated with electrophysiologic effects of ischemic preconditioning on myocardium in the human heart.
☆ This work was presented in part at the 68th Annual Scientific Sessions of the American Heart Association, Analheim, California, November 1995.
- Received August 10, 1995.
- Revision received March 4, 1996.
- Accepted March 11, 1996.