Search Results
Results 551 - 600 of 1541
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Ricci R - - 2002
BACKGROUND: Atrial fibrillation has a high incidence in patients wearing an implantable cardioverter defibrillator for ventricular tachyarrhythmias and may lead to palpitations, heart failure, angina, stroke and inappropriate defibrillator discharge. The aim of the study was to evaluate the efficacy of a dual chamber defibrillator with atrial antitachycardia functions in ...
Hoit Brian D - - 2002
Rapid atrial pacing produces atrial systolic and diastolic failure characterized by absent atrial booster pump function, increased atrial chamber stiffness, enhanced atrial conduit function, and atrial enlargement. However, the processes underlying these abnormalities are poorly understood. Therefore, we examined left atrial myocardium from dogs with rapid pacing-induced atrial failure (400 ...
Li Gui-Rong - - 2002
The different sodium channel currents (I(Na)) were reported in myocardium, neuron, and skeletal muscles. To study whether I(Na) is homogeneous within the heart, we applied whole-cell voltage clamp technique to evaluate fast voltage-gated I(Na) in atrial and ventricular myocytes isolated from guinea pig heart. It was found that the density ...
Gillis Anne M - - 2002
The case of a patient with frequent episodes of atrial fibrillation that organizes into atrial flutter following implantation of a dual chamber, rate adaptive pacemaker is reported. The atrial flutter was effectively pace-terminated following activation of the atrial antitachycardia pacing therapies in the pacemaker. This resulted in a decrease in ...
Verheule Sander - - 2002
OBJECTIVE: Rapid electrical activity in pulmonary veins (PVs) has been proposed as a mechanism for focal atrial fibrillation. The way in which the myocardial sleeve inside PVs can form a substrate for focal activity is not well understood. Therefore, we have studied tissue structure and connexin distribution at the veno-atrial ...
Tai Ching-Tai - - 2002
OBJECTIVES: This study was aimed at delineating the reentrant circuit of right atrial (RA) upper loop re-entry using noncontact three-dimensional mapping. BACKGROUND: Various forms of atypical atrial flutter including lower loop re-entry and left atrial flutter have been demonstrated. However, little is known about upper loop re-entry in the RA. ...
Cheng Jie - - 2002
BACKGROUND: The efficacy of ibutilide in conversion of atrial fibrillation and flutter (AFL) has been demonstrated. However, its electrophysiological effects on human atria have not been fully studied. METHODS AND RESULTS: Twelve patients with typical AFL were studied. Electrograms were recorded from the anterolateral right atrium, His bundle position, and ...
Meijler Frits L - - 2002
"Scaling deals with the structural and functional consequences of changes in size or scale among otherwise similar organisms." It plays a key role in all studies on comparative mammalian physiology and morphology. Heart weight is proportionally related to body weight and can be described by a straightforward, so-called allometric equation. ...
Meijboom Folkert - - 2002
The atria play an important role in adult congenital heart disease. Atrial function is often altered due to longstanding pressure or volume overload. Cardiac surgery inflicts lasting damage to the atria, which leads to loss of atrial compliance. Both the history of atrial overload and the atrial scarring form substrates ...
Villani Giovanni Q - - 2002
The effect of the atrial activity synchronization by single site right atrial pacing on atrial defibrillation threshold (ADFT) was investigated in patients with AF. Two series of randomized incremental cardioversion tests, with increasing energy levels from 0.5 to 10 J, were performed in 15 patients with recurrent episodes of idiopathic ...
Khan Ijaz A - - 2002
BACKGROUND: Conversion of atrial fibrillation (AFib) and flutter (AFlt) to sinus rhythm results in a transient mechanical dysfunction of atria (atrial stunning). Methods used as a means of assessing atrial stunning, atrial stunning after conversion of atrial fibrillation/flutter, and the cause, mechanisms, determinants of the extent, and drugs affecting atrial ...
Xie Fagen - - 2002
Theoretical and experimental studies have shown that restitution of the cardiac action potential (AP) duration (APD) plays a major role in predisposing ventricular tachycardia to degenerate to ventricular fibrillation, whereas its role in atrial fibrillation is unclear. We used the Courtemanche human atrial cell model and the Luo-Rudy guinea pig ...
Markides Vias - - 2002
There is an important association between heart failure and the development of atrial arrhythmias. Although most often associated with atrial fibrillation, there is some evidence to suggest an association between heart failure and other atrial arrhythmias and, in particular, atrial flutter and atrial tachycardia. The mechanisms by which these common ...
Date Taro - - 2002
BACKGROUND: Cardioversion of chronic atrial fibrillation or atrial flutter to sinus rhythm is often associated with transient atrial mechanical dysfunction, i.e. 'atrial stunning', which may increase the risk of subsequent thromboembolic events. We hypothesized that, because of its positive inotropic action, a low-dose isoproterenol infusion might improve postcardioversion atrial mechanical ...
Knauth Alison - - 2002
OBJECTIVES: We describe the structure of, and suggest an etiology for, the interatrial communication which can occur through the mouth of the coronary sinus. Based on the study of human embryos, we propose that the defect is best explained by dissolution of the wall of the coronary sinus adjacent to ...
Pomerantzeff Pablo Maria Alberto - - 2002
We present the case of a 33-year-old woman with atrial tachyarrhythmias and chest pain. The transthoracic echocardiography demonstrated an intrapericardial liquid mass confirmed as an aneurysm of the left atrial appendage by a nuclear magnetic imaging study. Aneurysmectomy was performed with the assistance of cardiopulmonary bypass with a bilateral submammary ...
Lau Chu-Pak - - 2002
Automatic mode switching (AMS) is now a programmable function in most contemporary dual chamber pacemakers. Atrial tachyarrhythmias are detected when the sensed atrial rate exceeds a "rate-cutoff," "running average," "sensor-based physiological" rate, or using "complex" detection algorithms. AMS algorithms differ in their atrial tachyarrhythmia detection method, sensitivity, and specificity and, ...
Ohkubo Kimie - - 2002
The patient was a 40-year-old woman with a history of surgery for atrial septal defect and catheter ablation for typical atrial flutter. An electrophysiological study was performed because she had palpitation and syncope. She had ectopic atrial rhythm originating from low lateral RA. Two focal atrial tachycardias ([1] superior vena ...
Hadian Djavid - - 2002
INTRODUCTION: Depression of sinus node function occurs in dogs and in patients after cessation of atrial flutter and fibrillation. We tested whether transient atrial pacing might produce similar changes in humans. METHODS AND RESULTS: We studied the impact of short-term rapid atrial pacing, simulating atrial tachyarrhythmias, on sinoatrial conduction time ...
Anderson Robert H - - 2002
Although knowledge of its existence has barely exceeded one century, the anatomic pathway for conduction of the cardiac impulse from atria to ventricles has been the source of much controversy, controversy that continues to the present day. This article describes how attention to the original descriptions, along with adherence for ...
Papa Marco - - 2002
BACKGROUND: The aim of this study was to evaluate the prevalence and prognostic implications of the association between atrial septal aneurysm (ASA) and fetal arrhythmias in a population of high risk fetuses. METHODS: One thousand three hundred and two fetal echocardiograms performed during high risk pregnancies from the 17th to ...
Stöllberger C - - 2002
Since in atrial fibrillation more than 90% of the thrombi are located in the left atrial appendage, an "elimination" of the left atrial appendage, either by resection or occlusion, seems an attractive alternative to oral anticoagulation. Although frequently regarded as an useless appendage, data from animal and human investigations show ...
Raymond Ronald J - - 2002
OBJECTIVES: The aim of this study was to evaluate the relationships between echocardiographic findings and clinical outcomes in patients with severe primary pulmonary hypertension (PPH). BACKGROUND: Primary pulmonary hypertension is associated with abnormalities of right heart structure and function that contribute to the poor prognosis of the disease. Echocardiographic abnormalities ...
Mangrum J Michael - - 2002
The implantable atrial defibrillator is a developing therapeutic option for paroxysmal atrial fibrillation, but shock related discomfort continues to be a limiting factor. To further characterize successful defibrillation, the relationship between reverse atrial electrical remodeling and internal atrial defibrillation thresholds in canines with chronic atrial fibrillation was examined. Testing was ...
Pavin Dominique - - 2002
The case of a 13-year-old child with an unusually localized "focal" permanent atrial tachycardia is reported. Electrophysiologic study showed that the earliest atrial activation occurred in the distal coronary sinus and preceded the atrial depolarization recorded along the endocardial side of the lateral part of the mitral annulus. Distal coronary ...
Pakarinen S - - 2002
AIMS: An inherent limitation of single lead VDD pacing is the inability to stimulate the atria. Reprogramming and upgrading the pacemaker system may be required when sinus node dysfunction, atrial undersensing, or atrial fibrillation develop. We evaluated whether routine clinical information is sufficient to select patients to benefit in long-term ...
Kandori A - - 2002
Two cases of fetal tachycardia are reported: atrial flutter and fibrillation. The waveforms from each case were detected by fetal magnetocardiograms (FMCGs) using a 64-channel superconducting quantum interference device (SQUID) system. Because the magnitude of supraventricular arrhythmia signals is very weak, two subtraction methods were used to detect the fetal ...
Kamkin Andre - - 2002
Atrial fibroblasts are considered to modulate the contractile activity of the heart in response to mechanical stretch. In this study we examined whether atrial fibroblasts are possibly involved in bradyarrhythmia, which is a severe complication after myocardial infarction. For this purpose, transmembrane electrical potentials were recorded in cardiac fibroblasts near ...
Shiga Tsuyoshi - - 2002
OBJECTIVES: Nifekalant is a class III antiarrhythmic drug, which prolongs the refractory period of the atrial and ventricular myocardium, without negative inotropic action. Intravenous nifekalant was administered in four patients with atrial tachyarrhythmia and severe heart failure to terminate or prevent atrial tachyarrhythmia. METHODS AND RESULTS: Two of three episodes ...
Musa H - - 2002
Adenosine exerts multiple receptor-mediated effects in the heart, including a negative chronotropic effect on the sinoatrial node. The aim of this study was to investigate the distribution of the equilibrative nucleoside transporter rENT1 in rat sinoatrial node and atrial muscle. Immunocytochemistry and/or immunoblotting revealed abundant expression of this protein in ...
Gölba┼či Z - - 2002
AIMS: Left atrial appendage thrombi are believed to be the source of embolism in patients with rheumatic mitral stenosis in atrial fibrillation. There are a few studies which search the effects of left atrial appendage dysfunction in patients with mitral stenosis in sinus rhythm. METHODS AND RESULTS: Left atrial appendage ...
Koshimizu Taka-Aki - - 2002
Atrial standstill is electrophysiologically characterized by the loss of spontaneous excitation in atrial muscle and the inability to cause action potential firing upon electrical stimulation. Clinical diagnosis of transient standstill of the right atrium was made in a patient with acute occlusion of the right coronary artery and acute renal ...
Oneglia Carlo - - 2002
We report the case of a patient with atrial fibrillation on standard electrocardiogram who underwent transesophageal echocardiography to rule out presence of thrombi in heart cavities. Pulsed-wave Doppler investigation revealed multiphasic waves consistent with atrial fibrillation in the left atrial appendage, while in the right atrial appendage, a biphasic flow ...
Ogawa Masahiro - - 2002
INTRODUCTION: Heterogeneity of ventricular repolarization plays a major role in reentrant tachyarrhythmias in cardiac tissue. However, the role of atrial repolarization added activation time (AT) to refractoriness in atrial vulnerability has not been investigated in detail. METHODS AND RESULTS: The study population consisted of 34 patients: 18 with atrial fibrillation ...
Kale M - - 2002
BACKGROUND: Early reports have shown that pacing the atria at a site or sites other than the right atrial appendage may prevent atrial fibrillation. Our centre has shown that pacing the atrial septum reduces the duration of atrial activation which is an important determinant of predisposition to paroxysmal atrial fibrillation. ...
Kanagaratnam Prapa - - 2002
OBJECTIVES: The aim of this study was to determine the relationship between immunolocalized gap-junctional proteins and human atrial conduction. BACKGROUND: As a determinant of intercellular conductance, gap-junctional coupling is considered to influence myocardial conduction velocity. This study tested the hypothesis that the quantity of immunodetectable atrial gap-junctional proteins, connexin40 (Cx40) ...
Hoffmann Ellen - - 2002
The aim of this study was to evaluate the clinical use of a new three-dimensional mapping system as a guide for catheter ablation of ectopic atrial tachycardia. A series of 42 consecutive patients with drug refractory ectopic atrial tachycardia was studied in a prospective observational trial with the electroanatomic mapping ...
Lönnerholm Stefan - - 2002
BACKGROUND: The Maze procedure is a curative surgical therapy for atrial fibrillation, restoring sinus rhythm and improving quality of life. Because the procedure results in tissue scarring, the atrial transport function is most likely affected. METHODS: Seventeen patients with paroxysmal atrial fibrillation underwent the Maze III procedure without any concomitant ...
Wu Richard C - - 2002
Catheter ablation has evolved from an experimental technique to first-line therapy for the treatment of atrial flutter. Atrial flutter is characterized by a macroreentrant atrial tachycardia circuit. Successful ablation of atrial flutter involves (1) mapping the atrial flutter to define the conduction zones within the re-entrant circuit to determine whether ...
Patel Vickas V - - 2002
This study sought to validate the accuracy of magnetic electroanatomic mapping (MEAM) for determining cardiac chamber size in a clinically relevant situation. The authors chose to compare LA size measured by MEAM to that assessed by two-dimensional guided M-mode echocardiography. The study included 37 patients with drug refractory paroxysmal atrial ...
De Ponti Roberto - - 2002
INTRODUCTION: Better understanding of atrial propagation during sinus rhythm (SR) in normal hearts under the most normal physiologic conditions may be propaedeutic to pathophysiologic studies of complex atrial arrhythmias. In this study, qualitative and quantitative analyses of sinus impulse propagation in both atria were performed by electroanatomic mapping in patients ...
Zupan Igor - - 2002
In animal and human studies, it has been shown that atrial fibrillation shortens the atrial refractory period and impairs its rate adaptation. The objective of this study was to evaluate the effects of high-rate pacing on sinus node function and intra-atrial conduction. Eight dogs were subjected to rapid atrial pacing ...
Tritto M - - 2002
We describe a case of post-incisional atrial tachycardia resembling typical atrial flutter on the surface ECG. Typical atrial flutter reentry was ruled out by the results of activation and entrainment mapping. Nevertheless, overdrive pacing from the lateral edge of the cavo-tricuspid isthmus produced tachycardia entrainment with concealed fusion associated with ...
Brockmeier Konrad - - 2002
Atrial reentrant tachycardia (ART) is not an uncommon complication in patients after surgery for congenital heart defects, particularly after extensive atrial procedures with sutures lines or baffeling maneuvers. Primary atrial flutter is a rare dysrhythmia in newborns. Two issues of ART or atrial flutter can be addressed by the esophageal ...
Daoud Emile G - - 2002
INTRODUCTION: The purpose of this study was to investigate the effect of ablation of right atrial flutter upon sinus node function in humans. METHODS AND RESULTS: This study enrolled 35 patients. Twenty-four patients (16 men and 8 women; age 68 +/- 11 years) were referred for ablation of persistent atrial ...
Takei M - - 2001
Atrial electrical remodeling is thought to be the cause of the maintenance of atrial fibrillation (AF). Although the initiation and maintenance of AF is partially associated with autonomic nervous tone, vagally mediated AF does not tend to become permanent. Therefore, the effects of preceding vagal stimulation (VS) on the atrial ...
Simantirakis E N - - 2001
AIMS: To examine whether atrial and ventricular effective refractory periods exhibit circadian variation and whether the latter is correlated with fluctuations in autonomic nervous system tone. METHODS AND RESULTS: We studied 24 patients aged 67.1 +/- 9.6 years, 11 of whom were paced for complete heart block and 13 for ...
Sato T - - 2001
Clinical experience suggests that sodium channel blockers are effective in converting atrial fibrillation of recent onset but not chronic atrial fibrillation. We investigated changes in the electrophysiologic effects of pilsicainide, a pure sodium channel blocker, on the canine atrium during chronic rapid pacing (400/min). Three pairs of bipolar electrodes were ...
Kuniyoshi Y - - 2001
BACKGROUND: To develop new methods for achieving bradycardia, we studied the feasibility of producing transient, reversible bradycardia with atrial stimulation and cooling of the sinoatrial node. METHODS: In an animal study, the atrium was stimulated electrically during the refractory period of the atrioventricular node. Alternatively, an area of the sinoatrial ...
Linde C - - 2001
Bipolar leads have been shown to provide superior sensing conditions compared to unipolar leads as bipolar sensing is less susceptible to interference. However, the mechanical long-term integrity and longevity of bipolar leads is inferior to that of unipolar leads. A prospective randomized, multicenter study was performed to investigate a new ...
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