QT interval and QT dispersion measured with the threshold method depend on threshold level

被引:21
作者
Batchvarov, V [1 ]
Yi, G [1 ]
Guo, XH [1 ]
Savelieva, I [1 ]
Camm, AJ [1 ]
Malik, M [1 ]
机构
[1] St George Hosp, Sch Med, Dept Cardiol Sci, London SW17 0RE, England
来源
PACE-PACING AND CLINICAL ELECTROPHYSIOLOGY | 1998年 / 21卷 / 11期
关键词
QT interval; QT dispersion; computerized measurement; threshold level;
D O I
10.1111/j.1540-8159.1998.tb01184.x
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Various computerized methods with multiple parameter options for measurements of the QT interval now are available. The optimum parameter setting for most algorithms is not known. This study evaluated the influence of the threshold level applied on the T wave differential on the QT interval and its dispersion measured in normal and abnormal electrocardiograms (ECGs). Seven hundred sixty ECGs recorded in 76 normal subjects and 630 in 63 patients with hypertrophic cardiomyopathy (HCM) (10 consecutive recordings in each individual) were analyzed. in each lead of each EGG, the QT interval was measured by the threshold method applied to the first differential of the T wave. The threshold level was varied between 5% and 30% of the T wave maximum in 1% steps, resulting in 26 different choices of QT measurements. With each choice the maximum QTc and the QT dispersion (QTd, standard deviation of the QT in all 12 leads) were obtained for each recording. The maximum QTc was significantly longer in HCM patients than in normal subjects (P < 0.001) at all threshold levels except between 5% and 7%. The QTd was significantly greater in HCM patients at all threshold levels. The QTc and QTd changed significantly with the threshold level. The maximum QTc varied up to 60 ms in normal subjects and up to 70 ms in HCM patients, depending on the threshold level. Thus, the QT interval and its dispersion measured with the threshold method applied to the first T wave differential depended significantly on the threshold level in both normal and diseased hearts. All programmable options of available automatic instruments should be examined carefully before any study, and all algorithmic details should be systematically presented.
引用
收藏
页码:2372 / 2375
页数:4
相关论文
共 13 条
[1]  
BORTOLAN G, 1996, VALIDATION QT DISPER, P665
[2]   COMPARISON OF QT DISPERSION IN HYPERTROPHIC CARDIOMYOPATHY BETWEEN PATIENTS WITH AND WITHOUT VENTRICULAR ARRHYTHMIAS AND SUDDEN-DEATH [J].
BUJA, G ;
MIORELLI, M ;
TURRINI, P ;
MELACINI, P ;
NAVA, A .
AMERICAN JOURNAL OF CARDIOLOGY, 1993, 72 (12) :973-976
[3]  
DAVEY P, 1994, BRIT HEART J, V71, P268
[4]   NEW ALGORITHM FOR QT INTERVAL-ANALYSIS IN 24-HOUR HOLTER ECG - PERFORMANCE AND APPLICATIONS [J].
LAGUNA, P ;
THAKOR, NV ;
CAMINAL, P ;
JANE, R ;
YOON, HR .
MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING, 1990, 28 (01) :67-73
[5]   HYPERTROPHIC CARDIOMYOPATHY - DISCUSSION OF NOMENCLATURE [J].
MARON, BJ ;
EPSTEIN, SE .
AMERICAN JOURNAL OF CARDIOLOGY, 1979, 43 (06) :1242-1244
[6]   Accuracy of four automatic QT measurement techniques in cardiac patients and healthy subjects [J].
McLaughlin, NB ;
Campbell, RWF ;
Murray, A .
HEART, 1996, 76 (05) :422-426
[7]  
MCLAUGHLIN NB, 1995, INFLUENCE T WAVE AUT, P777
[8]   COMPUTER QUANTITATION OF Q-T AND TERMINAL T-WAVE (AT-ET) INTERVALS DURING EXERCISE - METHODOLOGY AND RESULTS IN NORMAL MEN [J].
ODONNELL, J ;
KNOEBEL, SB ;
LOVELACE, DE ;
MCHENRY, PL .
AMERICAN JOURNAL OF CARDIOLOGY, 1981, 47 (05) :1168-1172
[9]   QT INTERVAL MEASUREMENT BY A COMPUTER-ASSISTED PROGRAM - A POTENTIALLY USEFUL CLINICAL-PARAMETER [J].
PUDDU, PE ;
BERNARD, PM ;
CHAITMAN, BR ;
BOURASSA, MG .
JOURNAL OF ELECTROCARDIOLOGY, 1982, 15 (01) :15-21
[10]   Report of the 1995 World Health Organization International Society and Federation of Cardiology Task Force on the Definition and Classification of Cardiomyopathies [J].
Richardson, P ;
McKenna, W ;
Bristow, M ;
Maisch, B ;
Mautner, B ;
OConnell, J ;
Olsen, E ;
Thiene, G ;
Goodwin, J ;
Gyarfas, I ;
Martin, I ;
Nordet, P .
CIRCULATION, 1996, 93 (05) :841-842