QT dispersion was originally proposed to measure spatial dispersion of ventricular recovery times. Later, it was shown that QT dispersion does not directly reflect the dispersion of recovery times and that it results mainly from variations in the T loop morphology and the error of QT measurement. The reliability of both automatic and manual measurement of QT dispersion is low and significantly ...

BACKGROUND The aim of the study was to evaluate the effect that coronary artery bypass grafting (CABG) and aneurysmectomy in the same session have on QT dispersion (QTd) in moderate or severe left ventricular dysfunction. METHODS Forty-four patients underwent QT interval analyses before and 1 month after aneurysmectomy and CABG. QT interval and QTd were corrected for heart rate using the squa...

Changes in the QT and QTc intervals were studied in 16 patients by atrial pacing at rates of 100, 130, and 150 beats/minute. In all patients the measured QT shortened when the atrial paced rate was increased, but when corrected for heart rate the QTc lengthened. Intravenously administered propranolol produced a bradycardia and a lengthening of the QT interval in 15 of the 16 patients studied. W...

We examined the relationship between changes in heart rate and the measured QT interval of the electrocardiogram in healthy subjects after exercise and during breath holding, hyperventilation, the dive reflex, the Valsalva maneuver, and the cold-pressor test. The tachycardia of exercise was accompanied by the familiar shortening of the QT interval, but substantial heart rate changes encountered...

BACKGROUND Congenital long-QT syndrome is a disorder resulting in ventricular arrhythmias and sudden death. The most common forms of the long-QT syndrome, types 1 and 2, are caused by mutations in the potassium-channel genes KCNQ1 and KCNH2, respectively. Although inheritance of the long-QT syndrome is autosomal dominant, female predominance has often been observed and has been attributed to an...

BACKGROUND Prolongation of the QT interval after exercise can be used to help diagnose long-QT syndrome, especially when the resting QT interval is borderline. The aim of this study was to determine the normal ranges for QT and corrected QT in the recovery phase after exercise in children. METHODS AND RESULTS Ninety-four volunteer boys and girls aged 8 to < 17 years without any history of hea...

PURPOSE To evaluate the effects of sunitinib, a multitargeted tyrosine kinase inhibitor, on the QT interval in patients with cancer. EXPERIMENTAL DESIGN Patients received sunitinib loading doses (150-200 mg) on days 3 and 9 and maintenance doses (50 mg/d) on days 4 to 8. Moxifloxacin (day 1), placebo (day 2), and granisetron [with placebo (day 2) or sunitinib (days 3 and 9)] were also adminis...

The potassium voltage-gated channel KCNH2 is a well-known gene in which mutations induce familial QT interval prolongation. KCNH2 is suggested to be a risk gene for schizophrenia. Additionally, the disturbance of autonomic control, which affects the QT interval, is known in schizophrenia. Therefore, we speculate that schizophrenic patients have characteristic features in terms of the QT interva...

INTRODUCTION Objective of this study was to determine the optimal (most heritable) phenotype for gene finding studies of QT interval in the general population. We also studied the extent to which heritability of QT interval can be explained by genes that also influence resting heart rate. METHODS AND RESULTS Subjects in this classic twin study were 105 monozygotic and 256 dizygotic female twi...

Measurement of QT dispersion as calculated from the 12-lead ECG has emerged as a non-invasive assessment for degree of myocardial inhomogeneity. Increased QT dispersion predicts sudden cardiac death in variety of disease states such as acute myocardial infarction and hypertrophic cardiomyopathy. To improve identification of athletes at high risk of sudden death, resting electrocardiograms were ...