AIMS Beta-blockers are the standard of care for the treatment of long QT syndrome (LQTS), and have been shown to reduce recurrent syncope and mortality in patients with type 1 LQTS (LQT1). Although beta-blockers have minimal effect on the resting corrected QT interval, their effect on the dynamics of the non-corrected QT interval is unknown, and may provide insight into their protective effects...

Prolongation of the QT interval of the ECG represents an imbalance in cardiac autonomic function and may predict cardiac arrhythmia. Vagal activity protects against prolongation of the QT interval which may be associated with flattening of the T-wave of the ECG. The changes in QT interval, T-wave amplitude and respiratory sinus arrhythmia (RSA) were studied after i.v. administration of atropine...

A case of methadone-induced torsades de pointes is presented to demonstrate clinical features that predispose patients to this serious cardiac arrhythmia. A patient who was receiving methadone maintenance treatment for heroin addiction presented to the hospital with dizziness and near-syncope. He was taking a relatively high dose of methadone but was not taking any concomitant cytochrome P450 i...

Several QT correction (QTc) formulas have been used for assessing the QT liability of drugs. However, they are known to under- and over-correct the QT interval and tend to be specific to species and experimental conditions. The purpose of this study was to determine a suitable formula for halothane-anesthetized dogs highly sensitive to drug-induced QT interval prolongation. Twenty dogs were ane...

OBJECTIVES QT interval prolongation is prevalent among patients with Takotsubo cardiomyopathy (TC), whereas torsades de pointes (TdP) has rarely been reported in these patients. We studied all peer-reviewed reports on TC-associated QT interval prolongation and all peer-reviewed reports on TC-associated TdP to characterize the clinical circumstances leading to TdP in patients with TC. METHODS ...

QT dispersion (QTd) is a measure of interlead variations of the surface 12-lead electrocardiogram (ECG). Increased QTd, found in various cardiac diseases, reflects cardiac instability and is associated with increased risk for cardiac death. Research suggests a link between antipsychotics, ECG abnormalities (QT prolongation) and increased sudden cardiac mortality rates. However, QTd analysis has...

Sudden unexplained/unexpected death (SUDEP) in epilepsy is a major cause of death accounting for 7-17% of the mortality among epileptic patients. Prolongation of QT-interval has been issued as a major mechanism in SUDEP since it is associated with fatal cardiac arrhythmias. This condition may be further precipitated by anti-epileptic treatment. Despite thorough literature research, we did not f...

BACKGROUND The development of atrium-selective antiarrhythmic agents is a current strategy for inhibiting atrial fibrillation (AF). The present study investigated whether the natural flavone acacetin from the traditional Chinese medicine Xuelianhua would be an atrium-selective anti-AF agent. METHODS AND RESULTS The effects of acacetin on human atrial ultrarapid delayed rectifier K(+) current ...

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...