Lack of association between QT dispersion and blood pressure response during dental surgery

1. It is well known that dental surgery induces increases in blood pressure. However, the factors influencing this increase are not yet fully understood. We have determined the relationship between QTc (= QT/RR(1/2), with RR being the R-R interval in seconds) dispersion, measured with a 12-lead surface electrocardiogram, and changes in blood pressure during tooth extraction. 2. Both QTc dispersion and the power spectrum of R-R variability were determined before the dental surgery was undertaken. The low-frequency (LF; 0.041-0.140 Hz), high- frequency (HF; 0.140-0.500 Hz) and total spectral powers (TF; 0.000-4.000 Hz) were calculated and the ratio of LF to HF and the percentage of HF relative to TF (%HF; HF/TF x 100) were used as indices of sympathovagal balance and parasympathetic activities, respectively. 3. In the present study, QTc dispersion failed to correlate with LF/HF and %HF. Systolic blood pressure and pulse rate increased significantly during tooth extraction; however, changes in these variables failed to correlate with QTc dispersion. 4. These results suggest that QTc dispersion is not associated with the power spectrum of R-R variability and that it does not affect the blood pressure response during tooth extraction.