AIMS Repolarization has rate-dependent and rate-independent components. A function considering such components separately was validated in canine Purkinje fibres and applied to the QT/RR relation in humans. METHODS AND RESULTS Action potential duration (APD) was measured in Purkinje fibres during steady-state pacing at different cycle lengths (CL) and after prolonged quiescence (APD(0)). The ...

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...

BACKGROUND Universal QT correction formulae have been shown to under or overcorrect the QT interval duration. Individual QT-R-R modeling has been proposed as a preferable solution for heart rate correction of QT intervals. However, the QT-R-R relationship stability over time needs to be evaluated. METHODS The present report is part of randomized, double-dummy, and placebo-controlled 4-way cro...

BACKGROUND Although QT prolongation is associated with increased risk of torsade de pointes (TdP), the precise relationship is not well defined. AIM To evaluate the performance of a QT nomogram in assessing the risk of TdP from QT-RR combinations. DESIGN Systematic review. METHODS We systematically searched MEDLINE/EMBASE for cases of drug-induced TdP. Controls were patients taking non-ca...

Background: Although QT prolongation is associated with increased risk of torsade de pointes (TdP), the precise relationship is not well defined. Aim: To evaluate the performance of a QT nomogram in assessing the risk of TdP from QT– RR combinations. Design: Systematic review. Methods: We systematically searched MEDLINE/ EMBASE for cases of drug-induced TdP. Controls were patients taking non-ca...

Background: Cirrhosis as the final stage of progressive fibrosis of liver can affect other organs such as lungs, kidneys and heart. "Cirrhotic cardiomyopathy" involves the electrophysiological abnormalities such as QT interval prolongation. We assessed correlation between corrected QT interval prolongation and severity of cirrhosis based on Child Classification in each ECG lead. ...

background: qt interval parameters have been suggested as a predictor of lethal arrhythmia and mortality in patients with myocardial infarction. the aim of the present study was to compare the value of qt interval indices in patients presenting with non-st-segment elevation myocardial infarction (nstemi) between a group of patients with type 2 diabetes mellitus and a nondiabetic group of patien...

in this paper, we study the chebyshev centres of bounded subsets of normed spaces and obtain a norm inequality for relative centres. in particular, we prove that if t is a remotal subset of an inner product space h, and f is a star-shaped set at a relative chebyshev centre c of t with respect to f, then llx - qt (x)1i2 2 ilx-cll2 + ilc-qt (c) 112 x e f, where qt : f + t is any choice function s...

Long QT intervals in the ECG have long been associated with sudden cardiac death. The congenital long QT syndrome was first described in individuals with structurally normal hearts in 1957.1 Little was known about the significance of a short QT interval. In 1993, after analyzing 6693 consecutive Holter recordings Algra et al concluded that an increased risk of sudden death was present not only ...

Prolonged QT interval is suggested to indicate an increased risk of sudden cardiac death in certain clinical conditions such as diabetes mellitus. We investigated whether the individual QT interval is an indicator of an autonomic state. An ambulatory 24-hour ECG was recorded in 53 subjects from different clinical backgrounds. Power spectral components of heart rate variability (HRV) and the QT ...