Search Results
Results 251 - 300 of 1288
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Namba Tsunetoyo - - 2007
PURPOSE: The aim of this study was to investigate whether bipolar electrode potentials (BEPs) reflect local myocardial repolarization dynamics, using computer simulation. METHODS: Simulated action potential and BEP mapping of myocardial tissue during fibrillation was performed. The BEP was modified to make all the fluctuations have the same polarity. Then, ...
Ghanem Raja N RN Medtronic Cardiac Rhythm Disease Management, Minneapolis, MN, USA. - - 2007
Sudden cardiac death remains the leading cause of death, claiming more than 1000 lives per day in the United States alone. Noninvasive means to diagnose rhythm disorders of the heart have relied heavily on the 12-lead electrocardiogram and, to a lesser extent, on higher-resolution body-surface mapping. These lack sensitivity and ...
Gallagher Mark M - - 2007
AIMS: To test the hypothesis that the QS interval of ventricular ectopic beats (VEBs) (ventricular ectopic QS interval, VEQSI) would provide a marker for the presence of structural heart disease and a predictor of mortality. METHODS AND RESULTS: We interviewed and examined 2332 patients undergoing Holter ECG monitoring for clinical ...
Segerson Nathan M NM University of Utah School of Medicine, Department of Internal Medicine, Division of Cardiology, Salt Lake City, Utah, USA. - - 2008
Increased spatial and temporal dispersion of repolarization contributes to ventricular arrhythmogenesis. Beat-to-beat fluctuations in T-wave timing are thought to represent such dispersion and may predict clinical events. The purpose of this study was to assess whether a novel noninvasive measure of beat-to-beat instability in T-wave timing would provide additive prognostic ...
Vyas Himeshkumar - - 2008
BACKGROUND: Although cardiac mechanical dysfunction has not been reported in congenital long QT syndrome (LQTS), theoretically abnormal cardiac repolarization may confer a substrate for mechanical dysfunction via calcium overload during the prolonged plateau period. We report the first clinical descriptions of a patient who supports this hypothesis. METHODS: Clinical, electrocardiographic, ...
Zhao Guoan - - 2007
Intracellular Ca(2+) and Ca(2+)-dependent signaling molecule play an essential role in the genesis of long-QT (LQT) syndrome-related ventricular arrhythmias. The effect of calcium-channel antagonist verapamil on repolarization heterogeneity of ventricular myocardium was assessed in an in vitro rabbit model of LQT syndrome. By using the monophasic action potential (MAP) recording ...
Falcón-Chévere Jorge L - - 2007
Sildenafil citrate is a drug used in the treatment of erectile dysfunction. It is an inhibitor of the enzyme phosphordiesterase-5; it slows down the breakdown of c-GMP and nitrous oxide. The cardiac effects associated with Sildenafil citrate have been extensively studied in medical literature, especially its potent vasodilatory effect when ...
Tomizawa Yasuko - - 2007
Titanium and its alloys are considered reliable materials commonly used in heart surgeries. A patient had severe inflammation at the median sternotomy wound develop after open heart surgery. Sternal wires were removed and were found to be seriously corroded on most of the surface. Energy dispersive spectroscopy identified titanium as ...
Gür Mustafa - - 2007
OBJECTIVE: Afterload is increased in hypertensive patients and increased afterload associated with both ventricular repolarization inhomogeneity and impaired elastic properties of aorta. Thus, we investigated whether QT dispersion (QTd), which is a reflection of ventricular repolarization inhomogeneity, is related to aortic elastic properties in patients with hypertension. METHODS: Overall 113 ...
Altin T - - 2007
Torsade de pointes occuring due to a long QT interval is a rare but potentially fatal arrhythmia. Acquired long QT develops most commonly because of drugs that prolong ventricular repolarization. It has been reported that fluoroquinolone antimicrobials prolong the corrected QT interval but rarely cause torsade de pointes. A patient ...
Ahmad Kamran - - 2007
One of the most feared potential adverse effects of many drugs is life threatening or fatal arrhythmia--particularly torsade de pointes (TdP) ventricular tachycardia in conjunction with QT prolongation. To fully understand the implications of QT prolongation, it is essential to have an understanding of the ion currents that comprise repolarization ...
Patanè Salvatore - - 2009
Torsade de pointes is a form of polymorphic ventricular tachycardia occurring in a setting of prolonged QT interval on surface electrocardiogram. Several drugs have been shown to prolong cardiac repolarization predisposing to torsade de pointes ventricular tachycardia. We present a case of torsade de pointes in a 72-year-old Italian woman ...
Kilic Harun - - 2007
Increased QT dispersion (QTd) is a noninvasive marker of an electrophysiologic abnormality associated with high mortality in coronary artery disease. The purposes of this study were to measure changes in QTd and ST-segment changes immediately before, during and after intracoronary balloon inflation and to determine whether the coronary artery vessel ...
Danielsson Christian - - 2007
BACKGROUND: The antiepileptic drugs (AEDs) phenytoin, phenobarbital, dimethadione, and carbamazepine cause a similar pattern of malformations in humans, with an increased risk after polytherapy. The teratogenicity has been linked to cardiac rhythm disturbances and hypoxic damage as a consequence of their common potential to inhibit a specific potassium ion current ...
Zhong Jiang-hua - - 2007
To study the effects of carvedilol on the transmural heterogeneity of ventricular repolarization in rabbits with congestive heart failure (CHF). Rabbits were randomly divided into 3 groups: control, CHF and carvedilol treated CHF group. Monophasic action potential duration (MAPD) in the 3 myocardial layers was simultaneously recorded. All the rabbits ...
Chung Eugene H - - 2007
The prevalence of metabolic syndrome (MS) was determined in patients aged < or =45 years who presented with acute myocardial infarction and underwent primary percutaneous coronary intervention. Two hundred twenty-three consecutive patients aged 18 to 45 years who underwent cardiac catheterization for acute myocardial infarction from June 2001 to December ...
Bär Karl-Jürgen - - 2007
Patients with schizophrenia have been reported to experience sudden cardiac death 3 times more likely than individuals from the general population. One important factor related to an increased risk of cardiac arrhythmias and sudden death is the prolongation of the QTc interval. This study examined whether acute psychosis might influence ...
De Ambroggi Luigi - - 2007
Left ventricular hypertrophy (LVH) is accompanied by specific changes of the cellular electrophysiology, which are potentially arrhythmogenic, mainly prolongation of action potential duration due to down-regulation of several K channels. Moreover, transmural dispersion of repolarization due to presence of cell types with different repolarization properties within the ventricular wall plays ...
Pastore Carlos Alberto - - 2007
OBJECTIVE: Cardiac resynchronization therapy (CRT) is an adjunct treatment for heart failure (HF) which associates with left bundle-branch block (LBBB) and is refractory to medical therapy. However, nearly 1/3 of the patients still do not respond, the reasons for which have yet to be determined. Additionally, experimental studies proved that ...
Sommargren Claire E - - 2007
In the electrocardiogram, the QT interval represents the time it takes the ventricular myocardium to repolarize. Prolongation of the QT interval indicates congenital or acquired abnormality of cardiac membrane channels. In the critical care setting, acquired long QT interval most commonly results from administration of common pharmacologic agents, including some ...
Russo Vincenzo - - 2007
BACKGROUND: Weight-stable obese subjects have an increased risk of arrhythmias and sudden death, even in the absence of cardiac dysfunction, and the risk of sudden cardiac death (SCD) with increasing weight is seen in both genders. The mechanism of unexplained deaths in obese patients is still unclear and may be ...
Iacoviello Massimo - - 2007
OBJECTIVES: The purpose of this work was to evaluate whether ventricular repolarization dynamicity predicts major arrhythmic events in patients with idiopathic dilated cardiomyopathy (DCM). BACKGROUND: Arrhythmic risk stratification in patients with DCM is still an open issue. Ventricular repolarization analysis should provide relevant information, but QT interval and QT dispersion ...
Arnaout Rima - - 2007
Long QT syndrome (LQTS) is a disorder of ventricular repolarization that predisposes affected individuals to lethal cardiac arrhythmias. To date, an appropriate animal model of inherited LQTS does not exist. The zebrafish is a powerful vertebrate model used to dissect molecular pathways of cardiovascular development and disease. Because fundamental electrical ...
Yavuz Bunyamin - - 2007
OBJECTIVES: The extent of atherosclerotic disease is identified as one of the most important predictors of long-term cardiac events in patients with coronary artery disease. Heart rate variability and QT dynamicity have been used as independent predictors for sudden death in coronary artery disease. Heart rate variability and QT dynamicity, ...
Milberg Peter - - 2007
BACKGROUND: Short QT syndrome (SQTS) is a newly described ion channelopathy, characterized by a short QT interval resulting from an accelerated cardiac repolarization, associated with syncope, atrial fibrillation, and sudden cardiac death due to ventricular fibrillation. As therapeutic options in SQTS are still controversial, we examined antiarrhythmic mechanisms in an ...
Saglam Hayrettin - - 2007
Lightning strike is a natural phenomenon with potentially devastating effects and represents one of the leading causes of cardiac arrest and death from environmental phenomena. Almost every organ system may be impaired as lightning passes through the human body preferring the pathways that the lowest resistance between the contact points. ...
Sezgin Alpay Turan - - 2007
QT interval dispersion reflects regional variations in ventricular repolarization and cardiac electrical instability. Previous studies have showed that QT interval dispersion changes during episodes of myocardial ischemia. Slow coronary flow (SCF) in epicardial coronary arteries is a rare and unique angiographic finding. Whether this pattern of flow is associated with ...
Dennis S G - - 2007
Sixty-four dogs were randomly assigned to receive either thiopentone or propofol and their electrocardiograms were recorded immediately before and shortly after they were anaesthetised. Thiopentone caused a marked increase in QT and JT intervals, a flattening of the T-wave and an increase in precordial QT dispersion. Propofol induced a less ...
Lazar Jason - - 2008
BACKGROUND: QT dispersion (QTD) reflects heterogeneity of myocardial repolarization, which is modulated by the central nervous system. Although largely studied in patients with cardiovascular disease, QTD is increased in acute stroke and this finding is an independent predictor of functional outcome and mortality following acute neurological events. HYPOTHESIS: The hypothesis ...
Chu Chih-Sheng - - 2007
Emerging evidence suggests that statins have a favorable impact on the reduction of arrhythmia events and sudden cardiac death in patients with structural heart disease. We aimed to investigate the possibly and directly favorable effects of statins on ventricular late potentials, QT dispersion, and transmural dispersion of repolarization attained by ...
Bonnemeier Hendrik - - 2007
BACKGROUND: Data from animal models suggest that inhibition of angiotensin converting enzymes result in an increased ventricular electrical stability after reperfusion in acute myocardial infarction (MI). As electrical stability is largely dependent on ventricular repolarization, we sought to determine the impact of low-dose intracoronary (i.c.) application of enalaprilat (EN) as ...
Ueda Hiroyasu - - 2007
BACKGROUND: QT dispersion is increased in acute myocardial infarction (AMI), but the relation of QT dispersion to prognosis has not yet been fully elucidated. HYPOTHESIS: The purpose of this study is to evaluate prospectively whether QT dispersion is associated with the risk of major adverse cardiac events (MACEs) and mortality ...
Newton-Cheh Christopher - - 2007
Electrocardiographic QT interval prolongation or shortening is a risk factor for sudden cardiac death. The study of Mendelian syndromes in families with extreme long and short QT interval duration and ventricular arrhythmias has led to the identification of genes encoding ion channel proteins important in myocardial repolarization. Rare mutations in ...
Mamalias Nikolaos - - 2007
BACKGROUND: Using a rat in vivo infarct model we tested the hypothesis that fetal cardiomyocyte (FCM) implantation would increase repolarization heterogeneity. METHODS: Four groups of rats were studied: two groups served as controls and underwent injection with FCM or culture medium in a region of the left ventricle (LV) supplied ...
Hooft van Huysduynen Bart - - 2008
OBJECTIVE: To assess the effect of pulmonary valve replacement (PVR) on the repolarization of patients with tetralogy of Fallot. BACKGROUND: Pulmonary valve regurgitation may cause right ventricular failure in adult patients with Fallot's tetralogy. In these patients, prolonged depolarization and disturbed repolarization are associated with ventricular arrhythmias and sudden cardiac ...
Hansen Stig - - 2007
BACKGROUND/AIMS: A long QT(C) interval has been described in a substantial fraction of patients with cirrhosis, but information on QT variation and dispersion is sparse. The aim was to determine QT variation with time and QT dispersion (QT(disp)). METHODS: The study population comprised 23 patients with cirrhosis, undergoing a haemodynamic ...
Watanabe Eiichi - - 2007
BACKGROUND: Prolongation of the action potential duration (APD) is observed in ventricular myocytes isolated from the failing heart. The rapid component (I(Kr)) and the slow component (I(Ks)) of the delayed-rectifier potassium current (I(K)) are major determinants of the APD, but less information is available on the genomic modulation of I(K) ...
Sabir Ian N IN Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, - - 2007
Clinical hypokalaemia is associated with acquired electrocardiographic QT prolongation and arrhythmic activity initiated by premature ventricular depolarizations and suppressed by lidocaine (lignocaine). Nevertheless, regular (S1) pacing at a 125 ms interstimulus interval resulted in stable waveforms and rhythm studied using epicardial and endocardial monophasic action potential (MAP) electrodes in Langendorff-perfused ...
Coronel Ruben - - 2007
OBJECTIVE: The contribution of regional electrophysiologic heterogeneity to the T-wave changes of long-term cardiac memory (CM) is not known. We mapped activation and repolarization in dogs after induction of CM and in sham animals. METHODS AND RESULTS: CM was induced by three weeks of AV-sequential pacing at the anterior free ...
Saponara Simona - - 2007
Cardiac effects of 3,5-dibenzoyl-4-(3-phenoxyphenyl)-1,4-dihydro-2,6-dimethylpyridine (DP7), a novel multidrug resistance (MDR) inhibitor, in Langendorff-perfused rat heart have been investigated and compared to that of nifedipine. Nifedipine decreased concentration-dependently (IC50=8.89+/-1.09x10(-8) M) left ventricular pressure leaving unaltered coronary perfusion pressure, whereas DP7 did not affect both parameters. Nifedipine did not modify both QRS ...
Sabir Ian N IN Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, - - 2007
The clinical effects of hypokalemia including action potential prolongation and arrhythmogenicity suppressible by lidocaine were reproduced in hypokalemic (3.0 mM K(+)) Langendorff-perfused murine hearts before and after exposure to lidocaine (10 muM). Novel limiting criteria for local and transmural, epicardial, and endocardial re-excitation involving action potential duration (at 90% repolarization, ...
Moore Hans J - - 2007
Bridging basic and clinical electrophysiology has been facilitated by monophasic action potential recordings. The electrocardiogram is a useful clinical approach in detecting abnormal repolarization, but falls short in depicting local repolarization details. The MAP waveform is a reflection of local transmembrane action potentials. We hope to convey a basic understanding ...
Baumgartner Daniela - - 2007
OBJECTIVE: To investigate electrophysiological and functional signs of myocardial damage in patients with propionic acidemia (PA), an inborn error of metabolism caused by deficiency of propionyl CoA carboxylase (PCC). STUDY DESIGN: In an observational longitudinal study 10 patients with PA (6 boys and 4 girls) ranging between 2.5 and 20.2 ...
Takahara Akira - - 2007
The chronic atrioventricular block dog is a useful model for predicting the future onset of drug-induced long QT syndrome in clinical practice. To better understand the arrhythmogenic profile of this model, we recorded the action potentials of the isolated ventricular tissues in the presence and absence of the class III ...
U─čur Bakiye - - 2007
PURPOSE: This study compared the intraoperative changes in the corrected QT dispersion and heart rate variability, predictors of autonomic cardiac function, in laparotomic and laparoscopic adnexal surgery. MATERIALS AND METHODS: The study was conducted on 46 American Society of Anaesthesiologists class I/II patients, aged 33-51 years, randomized to one of ...
Selvaraj Raja J - - 2007
OBJECTIVES: The aim of this study was to define the spatiotemporal distribution of intracardiac alternans and its relationship to body surface alternans in humans. BACKGROUND: Spatial heterogeneity of alternans exists in the animal heart owing to nonuniform calcium cycling and restitution kinetics. Patients with cardiomyopathy manifest similar myocardial substrate, which ...
Morita Shiho T - - 2007
OBJECTIVE: Transmural heterogeneity in the ventricular free wall, enhanced by the midmyocardial long action potential duration (APD) of M cells, plays an important role in the arrhythmogenesis of long QT syndrome. Although we observed dynamic expression of M cell phenotypes in the canine ventricular free wall, it is still unclear ...
Dumotier B M - - 2007
The last decade has been marked by the withdrawal from the market of several medicines whose use in patients has been associated with the development of torsade de pointes (TdP), a potentially life-threatening polymorphic tachycardia. In a few cases, TdP can degenerate into ventricular fibrillation and lead to sudden death, ...
Kijtawornrat, Anusak
Torsades de pointes (TdP) is a polymorphic ventricular tachycardia characterized by a distinctive pattern of undulating QRS complexes that twist around the isoelectric line. TdP has been associated with QT interval prolongation of the electrocardiogram; therefore, the QT interval has come to be recognized as a surrogate marker for the ...
Martinka J - - 2007
Index of vulnerability is a parameter based on ventricular gradient evaluating the risk of arrhythmia development. The index is derived from isointegral maps of the QT interval. Individual characteristics of isointegral maps are influenced by different factors, which contribute to the relatively high variability among measured parameters of maps in ...
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