著者

Daisuke Hazeki Masao Yoshinaga Hideto Takahashi Yuji Tanaka Yasue Haraguchi Mayumi Abe Masami Koga Toshiro Fukushige Masami Nagashima

出版者

日本循環器学会

雑誌

Circulation Journal (ISSN:13469843)

巻号頁・発行日

vol.74, no.8, pp.1663-1669, 2010 (Released:2010-07-23)

参考文献数

12

被引用文献数

13 33 8

---

Background: The corrected QT interval (QTc) according to Bazett's formula (QTc = QT/RR1/2) has been used in clinical practice. Bazett's formula, however, overcorrects the QT interval at fast heart rates and undercorrects it at low heart rates. Guidelines and some investigators have recommended using Fridericia's formula (QTc = QT/RR1/3) in these cases, especially in tachycardic subjects. The aim of the present study was to determine cut-offs for QTc suitable for screening pediatric subjects with prolonged QT intervals, based on manually measured values corrected by Fridericia's formula in a large number of subjects. Methods and Results: Three consecutive QT and RR intervals were measured in 4,655, 4,655, and 5,273 1st, 7th, and 10th graders, aged 6, 12, and 15 years, respectively. Each QT interval was corrected by Fridericia's formula, and mean values were calculated. Determination of the cut-offs for screening was based on the prevalence of abnormal electrocardiographic phenotypes of 1:1,164 and on the upper 0.025 percentile in the QTc distribution derived from previous studies. The tentative cut-offs suitable for screening subjects with prolonged QT intervals were 430 ms for 1st graders, 445 ms for 7th graders, and 440 and 455 ms for 10th grade boys and girls, respectively. Conclusions: These tentative cut-offs can be used to screen subjects with prolonged QT intervals in the clinical setting. Further studies are needed to confirm their validity.  (Circ J 2010; 74: 1663 - 1669)

著者

Masao Yoshinaga Yoshiaki Kato Yuichi Nomura Daisuke Hazeki Toshiaki Yasuda Kazuhiro Takahashi Takashi Higaki Yuji Tanaka Akihiro Wada Hitoshi Horigome Hideto Takahashi Kentaro Ueno Hiroshi Suzuki Masami Nagashima

出版者

日本不整脈学会

雑誌

Journal of Arrhythmia (ISSN:18804276)

巻号頁・発行日

vol.27, no.3, pp.193-201, 2011-07-25 (Released:2011-08-26)

参考文献数

27

---

Background: Electrocardiographic and molecular studies have clarified an association between sudden infant death syndrome (SIDS) and long QT syndrome (LQTS), and few data are available for the QT interval in infancy from birth to 1 year of age. Appropriate time of electrocardiographic screening is not clarified. Medical examinations during infancy are mandatory in Japan.Methods and Results: The study population included 1,058 infants. Electrocardiograms were collected with information of infants at birth and at examination. The QT intervals of three consecutive beats were measured in lead V5. Statistical analysis revealed that the following formula was appropriate to minimize the effect of heart rate for infants: corrected QT interval; QTc = QT interval/RR interval0.43. Subjects were divided into four groups as follows: 0–2, 3–6, 6–11, and 12–52 weeks of age. Tukey’s multiple comparison showed that the QTc intervals were longest (p<0.0001) in subjects who were 6–11 weeks of age.Conclusions: The QTc interval showed the highest peak at 6–11 weeks of age in infancy. The peak period of occurrence of SIDS is at approximately 2 months of age. An appropriate time of electrocardiographic screening for QT prolongation will be one month of age, and follow-up studies are needed.