Cold effect on qt dispersion in healthy subjects.
Thirty-one healthy subjects, aged 35 +/- 6 (21 to 48) years, were included in the study to evaluate the effect of ice water immersion on QT dispersion. There was no difference in the age between females (n = 11) and males (n = 20). Baseline, stress (at the end of ice water immersion, 4 degrees C, for 3 minutes) and recovery 12-lead electrocardiograms (ECGs) were recorded on each subject. During the test, a significant variability developed in both the QT dispersion (52 +/- 17, 68 +/- 25 and 59 +/- 21 ms; p = 0.015) and the corrected QT dispersion (56 +/- 17, 76 +/- 27 and 64 +/- 23 ms; p = 0.005), but not in the heart rate (74 +/- 11, 76 +/- 9, and 74 +/- 9 bpm, respectively; p = 0.447). There was no inter-sex difference in the baseline heart rate or QT dispersion, or in their response to ice water immersion. Age significantly correlated with the variation of QT dispersion to ice water immersion (r = 0.380, p = 0.035). With 37 years of age as a separation point, the variation of QT dispersion to ice water immersion was more obvious in the older group (28 +/- 22 vs. 10 +/- 19 ms, p = 0.023). In conclusion, cold may increase QT dispersion in healthy subjects, with a more obvious effect in the older ones.
Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung 807, Taiwan.
Chih-Sheng
CS
Chu
Tsung-Hsien
TH
Lin
Ye-Hsu
YH
Lu
Chih-Hsin
CH
Huang
Kun-Tai
KT
Lee
Hsueh-Wei
HW
Yen
Wen-Chol
WC
Voon
Wen-Ter
WT
Lai
Sheng-Hsiung
SH
Sheu
D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D003080:Cold Temperature / Q000009:adverse effects*; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D007101:Immersion; D008297:Male; D008875:Middle Aged; D012737:Sex Factors