BACKGROUND A paradoxical increase in the uncorrected QT interval during infusion of low-dose epinephrine appears pathognomonic for type 1 long-QT syndrome (LQT1). We sought to determine the diagnostic accuracy of this response among patients referred for clinical evaluation of congenital long-QT syndrome (LQTS). METHODS AND RESULTS From 1999 to 2002, 147 genotyped patients (125 untreated and ...

Preventing cardiac deaths remains one of the greatest challenges in medicine in the 21st Century. There is evidence to suggest QT peak prolongation identi�ies patients who are at risk of death or non-fatal myocardial infarction (MI) [1]. The next step to reduce the risk of these patients would be to �ind out whether there are potentially treatable conditions associated with QT peak prolongation...

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...

BACKGROUND To evaluate QT-interval dynamics in patients and in drug safety analysis, beat-to-beat QT-interval measurements are increasingly used. However, interobserver differences, aberrant T-wave morphologies and changes in heart axis might hamper accurate QT-interval measurements. OBJECTIVE To develop and validate a QT-interval algorithm robust to heart axis orientation and T-wave morpholo...

OBJECTIVE Prolongation of the QT interval and increased QT dispersion are associated with a poor cardiac prognosis. The goal of this study was to assess the long-term influence of the autonomic nervous system on the heart rate dependence of ventricular repolarization in patients with diabetic autonomic neuropathy (DAN). RESEARCH DESIGN AND METHODS We studied 27 subjects (mean age 51.8 years) ...

OBJECTIVE Recent studies have suggested that QT interlead variability (dispersion) on the surface electrocardiogram may have potential as a measure of recovery time dispersion. To test this hypothesis further QT dispersion occurring in sinus beats was compared with that in ventricular extrasystoles. DESIGN Simultaneous electrocardiograms were recorded at 50 mm/s during sinus rhythm in a drug ...

We consider the homogeneous Dirichlet problem for anisotropic parabolic equationut−∑i=1NDxi(|Dxiu|pi(x,t)−2Dxiu)=f(x,t) in cylinder Ω×(0,T), where Ω⊂RN, N≥2, is a parallelepiped. The exponents of nonlinearity pi are given Lipschitz-continuous functions. It shown that if pi(x,t)>2NN+2,μ=supQT⁡maxi⁡pi(x,t)mini⁡pi(x,t)<1+1N,|Dxiu0|max⁡{pi(⋅,0),2}∈L1(Ω),f∈L2(0,T;W01,2(Ω)), then has unique solution ...

OBJECTIVES To introduce a nomogram of the normal QT interval at various heart rates measured from 24 hour Holter ECG recordings in healthy subjects with respect to age and sex and to use the nomogram to characterise dynamic changes in QT interval in patients with idiopathic ventricular fibrillation (IVF) and the long QT syndrome (LQT). METHODS The study group consisted of 422 subjects: 249 he...

OBJECTIVE To compare the QT/RR relation in healthy subjects in order to investigate the differences in optimum heart rate correction of the QT interval. METHODS 50 healthy volunteers (25 women, mean age 33.6 (9.5) years, range 19-59 years) took part. Each subject underwent serial 12 lead electrocardiographic monitoring over 24 hours with a 10 second ECG obtained every two minutes. QT interval...