background: myocardial ischemia is one of several causes of prolonged qt dispersion. the aim of this study was to evaluate the effect that percutaneous coronary intervention has on the depolarization and repolarization parameters of surface electrocardiography in patients with chronic stable angina. methods: we assessed the effects of full revascularization in patients with chronic stable angin...

We address the problem of online change detection in multivariate datastreams, and we introduce QuantTree Exponentially Weighted Moving Average (QT-EWMA), a nonparametric change-detection algorithm that can control expected time before false alarm, yielding desired Run Length (ARL$_0$). Controlling alarms is crucial many applications rarely guaranteed by algorithms monitor datastreams without k...

Background: QT dispersion is the difference between the longest and the shortest QT intervals as measured from the 12 lead standard ECG. It reflects ventricular repolarisation heterogeneity which may lead to ventricular arrhythmias in certain cases. Myocardial ischemia plays a central role in the pathophysiology of prolonged QT dispersion leading to re-entrant type ventricular arrhythmias. Curr...

The n-dimensional cube Q is the graph whose vertices are the subsets of {1, . . . , n}, with two vertices adjacent if and only if their symmetric difference is a singleton. Clearly Q has diameter and radius n. Write M = n2n−1 = e(Q) for the size of Q. Let Q̃ = (Qt) M 0 be a random Q-process. Thus Qt is a spanning subgraph of Q n of size t, and Qt is obtained from Qt−1 by the random addition of a...

the relationship between qt dispersion and myocardial ischemia is still controversial. therefore, we aimed to investigate the relationship between qtd and the severity and extent of myocardial ischemia. in this cross-sectional study, 141 patients having symptoms of cad who referred to our medical center during 2009-2010, and were examined with myocardial isotope scan and ecg, were enrolled. bas...

Many drugs can significantly influence cardiac repolarisation causing an increased duration of this repolarisation phase, challenging the repolarisation reserve. This may set the stage for life-threatening ventricular arrhythmias such as torsades de pointes (TdP). TdP generally occurs in conjunction with a prolonged QT interval (QT) on the electrocardiogram. The Dutch Poisons Information Centre...

To evaluate whether heart-rate-induced changes of the QT interval are dependent on autonomic tone, we studied 13 healthy subjects, mean age 67.5 years. The maximal uncorrected QT from leads I, II, V1 and V6 was determined during atrial pacing at 90 beats/min and 130 beats/min before and after i.v. administration of propranolol, 0.1 mg/kg, and atropine, 0.02 mg/kg. Significant reductions (p less...

The electrocardiogram was recorded for 100 seconds in 50 patients with atrial fibrillation to determine the relations between QT intervals and both the mean and instantaneous ventricular rates. The mean ventricular rate was 94 beats per minute with a mean QT interval of 357 ms. The mean QTc, corrected beat by beat with Bazett's formula, was 444 ms--longer than reported for sinus rhythm. Between...

Purpose: It is thought that arrhythmias are responsible for sudden deaths in patients with mitral valve prolapse (MVP). QT intervals may predict malignant arrhythmia potential in these patients. The aim of the present study is to assess QT variables in patients with MVP. Methods : We studied 46 patients with non-rheumatic, uncomplicated and isolated MVP and 25 healthy control subjects. All indi...