Divergence of Endocardial QT Interval Components during Programmed Electrical Stimulation Including Observations during Induction of Sustained Ventricular Tachyarrhythmias

摘要: Measurements were made in 12 normal subjects and during induction ofsustained ventricular tachyarrhythmias 31 patients with remote myocardialinfarction. QT interval measurements semiautomatically withcomputer assistance the total was divided into early (QT 1 )and late 2 ) components. intervals dispersion betweentwo right endocardial sites plotted against degree ofprematurity of last extrastimulus (S , S 3 or 4 ). In controlgroup, shortened increasing prematurity ofthe (p 0.001). Slopes (positive) steeper withfaster pacing rates (600, 500, 400 ms) more extrastimuli (1 to 3).The relationship between lastextrastimulus flat, but slope slightly negative (p=0.05to,0.001) did not vary changes cycle length number ofextrastimuli. control group minor(95% CI 0-40 ms). During sustained ventriculartachyarrhythmias, longer (y intercepts)than 0.05 at 400-ms length) theirdispersion increased 0.05). Generally, shorter(p 600-ms ventriculararrhythmias comparison wasincreased length). QTinterval show an orderly predictable withprematurity subjects. These patternsdiffer tachyarrhythmias. Suchdifferences may be exploited derive clinically predictive usefulmeasurements.