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 ...

OBJECTIVE Typically detected via electrocardiograms (ECGs), QT interval prolongation is a known risk factor for sudden cardiac death. Since medications can promote or exacerbate the condition, detection of QT interval prolongation is important for clinical decision support. We investigated the accuracy of natural language processing (NLP) for identifying QT prolongation from cardiologist-genera...

OBJECTIVE To relate QT parameters to infarct size and inducibility during electrophysiological studies. DESIGN Analysis of a prospective register. SETTING University hospital. PATIENTS 64 patients with coronary artery disease and documented life threatening ventricular arrhythmias. INTERVENTIONS Measurements of QT-max, QTc-max, and QT dispersion (QT-d) on a simultaneous 12 lead ECG (50 ...

OBJECTIVE To investigate the role of the autonomic nervous system in determining QT interval and dispersion. PATIENTS AND METHODS 32 patients with chronic primary (idiopathic) autonomic failure (19 men, mean age 60 years) and 21 normal controls (11 men, mean age 59) without symptoms of ischaemic heart disease were studied retrospectively. Autonomic failure was diagnosed by a combination of sy...