摘要：Hill JA, O’Riordan MA, Bansal M, Fiutem J, Zahka K. Normal QT Response During Exercise Testing and Hyperventilation in Children. JEPonline 2012;15(1):65-75. Our goal was to describe normal heart rate (HR), QT interval, and Bazett’s-corrected QT (QTc) values during exercise testing in children, and to test our hypothesis that hyperventilation is associated with QTc prolongation in children. This study was a retrospective review of 200 consecutive normal exercise tests in 108 males and 92 females with low likelihood of Long QT Syndromes (LQTS) and no evidence of cardiac disease, with mean age 14.7 ± 4.0 yrs. The QT interval and RR interval were measured throughout exercise testing and hyperventilation. The QTc values were calculated using Bazett’s formula. A database of HR, QT, and QTc values is presented for standing baseline and hyperventilation, and throughout exercise and recovery. Heart rate and stage of testing had independent effects on repolarization throughout exercise and recovery, while age and sex did not. We constructed reference tables of mean QT and QTc values during exercise and recovery, referenced by HR and stage. With hyperventilation, mean HR increased by 22.7 ± 12.8 beats•min-1 , QT shortened by 26.3 ± 21.6 ms, and mean QTc lengthened by 30.3 ± 25.4 ms1/2 to 442 ± 26 ms1/2 (P<0.001). There were no significant sex, age, or HR effects on the magnitude of QTc prolongation with hyperventilation. This study provides the largest data set for repolarization behavior during exercise testing in children without evidence of heart disease. This is also the first time that the QTc has been shown to prolong with hyperventilation. It is unknown whether this is specifically related to hyperventilation or simply explained by a limitation in Bazett’s formula. It highlights exercising caution when using Bazett’s formula outside the narrow reliable HR 66 range, especially in children and even more so during exercise. Database of normal population data is perhaps more reliable in those situations, although further validation must be done to confirm its utility.
