Pacing and clinical electrophysiology : PACE
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Pacing Clin Electrophysiol · Jun 2004
Differences between study-specific and subject-specific heart rate corrections of the QT interval in investigations of drug induced QTc prolongation.
A computational study was designed to investigate the differences between the so-called study-specific and subject-specific heart rate corrections of QT interval. In 53 healthy subjects (25 women, mean age 26.7 +/- 8.7 years), serial 10-second electrocardiograms (ECG) were obtained during daytime hours. In each subject, 200 ECGs were selected representative of the individual QT/RR relationship. ⋯ The subject-specific corrections led to maximum errors in single milliseconds (error range of 2.4, 5.7, and 2.6 ms with linear, log/log linear, and exponential models, respectively) while the study-specific corrections led to substantially greater errors (error range of 17.8, 19.4, and 16.9 ms with linear, log/log linear, and exponential models, respectively). Both Bazett and Fridericia corrections led not only to substantial errors (error range of 28.3 and 16.9 ms) but also to regular bias with systematically false negative and false positive conclusions dependent on modeled heart rate acceleration and deceleration. Thus, subjects-specific corrections should be used in the intensive and definite studies aimed at providing the final answer on the ability of a drug to prolong the QT interval.
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Pacing Clin Electrophysiol · Apr 2004
Case ReportsPeripartum cardiomyopathy presenting with repetitive monomorphic ventricular tachycardia.
A 30-year-old asymptomatic pregnant woman at 38 weeks' gestation was noticed to have repetitive monomorphic ventricular tachycardia. A dilated left ventricle with moderately reduced systolic function was found on echocardiographic examination. To the best of our knowledge, a case of peripartum cardiomyopathy presenting with repetitive monomorphic ventricular tachycardia has not been previously reported.
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Pacing Clin Electrophysiol · Apr 2004
Case ReportsDual antegrade response tachycardia induced cardiomyopathy.
We report a rare case of tachycardia induced cardiomyopathy resulting from nearly incessant dual antegrade response tachycardia. Criteria necessary for sustaining dual antegrade responses are discussed, including: (1) sufficient antegrade dissociation of the AV node; (2) absence of retrograde conduction over each AV nodal pathway following antegrade conduction over its counterpart; (3) difference between fast and slow pathway conduction times exceeding His-Purkinje refractoriness; and (4) critical timing of sinus impulses relative to preceding AV nodal conduction. Both the arrhythmia and cardiomyopathy were successfully treated by slow pathway ablation.
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Pacing Clin Electrophysiol · Apr 2004
Randomized Controlled Trial Clinical TrialPhysician management of pacemaker and implantable cardioverter defibrillator advisories.
This study was designed to determine how physicians manage pacemaker (PM) and implantable cardioverter defibrillator (ICD) recalls and safety alerts (collectively "advisories") and to determine which factors influence physicians' clinical decisions. Although PM and ICD advisories affected over 500,000 patients in the past decade, physician clinical management of advisory devices has not been well studied. Advisories continue to occur frequently and are increasing in number and rate. ⋯ Physician consensus exists regarding the management of some PM and ICD advisories and can be used to guide clinical practice. Substantial differences of opinion, however, are present regarding the management of many other advisories. Evidence based guidelines incorporating the indication for device implantation and the likelihood of device malfunction would greatly facilitate clinical management of PM and ICD advisory devices.