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Cardiology, blood circulation, phlebology, Cardiologie, appareil circulatoire, phlébologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Cardiologie. Appareil circulatoire, Cardiology. Vascular system, Vaisseaux sanguins et lymphatiques, Blood and lymphatic vessels, Maladies vasculaires des membres. Pathologie de la veine cave. Maladies vasculaires diverses, Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous, Cardiopathie, Heart disease, Cardiopatía, Trouble excitabilité, Excitability disorder, Trastorno excitabilidad, Trouble rythme cardiaque, Arrhythmia, Arritmia, Ablation, Ablación, Appareil circulatoire pathologie, Cardiovascular disease, Aparato circulatorio patología, Cartographie, Cartography, Cartografía, Cathéter, Catheter, Catéter, Tachycardie auriculaire, Atrial tachycardia, and Taquicardia auricular

Background-This study investigated the electrophysiologic characteristics, atrial activation pattern, and effects of radiofrequency (RF) catheter ablation guided by noncontact mapping system in patients with focal atrial tachycardia (AT). Methods and Results-In 13 patients with 14 focal ATs, noncontact mapping system was used to map and guide ablation of AT. AT origins were in the crista terminalis (n=8), right atrial (RA) free wall (n=3), Koch triangle (n=1), anterior portion of RA-inferior vena cava junction (n= 1), and superior portion of tricuspid annulus (n=1); breakout sites were in the crista terminalis (n=5), RA free wall (n=5), middle cavotricuspid isthmus (n=2), and RA-superior vena cava junction (n=2). ATs arose from the focal origins (11 ATs inside or at the border of low-voltage zone), with preferential conduction, breakout, and spread to the whole atrium. After applications of RF energy on the earliest activation site or the proximal portion of preferential conduction from AT origin, 13 ATs were eliminated without complication. During the follow-up period (8±5 months), 11 (91.7%) of the 12 patients with successful ablation were free of focal ATs. Conclusions-Focal AT originates from a small area and spreads out to the whole atrium through a preferential conduction. Application of RF energy guided by noncontact mapping system was effective and safe in eliminating focal AT.

Cardiology, blood circulation, phlebology, Cardiologie, appareil circulatoire, phlébologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Cardiologie. Appareil circulatoire, Cardiology. Vascular system, Coeur, Heart, Trouble du rythme et de la conduction, Cardiac dysrhythmias, Trouble excitabilité, Excitability disorder, Trastorno excitabilidad, Trouble rythme cardiaque, Arrhythmia, Arritmia, Ablation, Ablación, Appareil circulatoire pathologie, Cardiovascular disease, Aparato circulatorio patología, Caractérisation, Characterization, Caracterización, Cardiopathie, Heart disease, Cardiopatía, Flutter auriculaire, Atrial flutter, Flutter auricular, Homme, Human, Hombre, Radiofréquence, Radiofrequency, and Radiofrecuencia

OBJECTIVES The aim of the study was to investigate the conduction properties and anisotropy of the crista terminalis (CT) in patients with atrial flutter (AFL) using non-contact mapping. BACKGROUND The CT is a posterior barrier during typical AFL. However, the CT has transverse conduction capabilities in patients with upper loop re-entry (ULR). METHODS Twenty-two patients (16 males, 63 ± 15 years) with typical AFL and ULR were included. Non-contact mapping of the right atrium during AFL and pacing from coronary sinus (CS) and low anterolateral right atrium (LARA) was performed to evaluate transverse conduction across the CT. During ULR, the longitudinal (CVL) and transverse (CVT) conduction velocity along and across the CT were measured. The width of the CT conduction gap was evaluated to guide radiofrequency ablation (RFA). RESULTS No transverse CT gap conduction was found during typical AFL. Transverse CT gap conduction was found in three patients during CS pacing and in three patients during LARA pacing. During ULR, CVL was greater than CVT (1.28 ± 0.43 vs. 0.73 ± 0.30 m/s, p < 0.001). The CVL/CVT ratio was 1.95 ± 0.77, which was inversely related to the CT gap width (15.7 ± 6.8 mm) (p < 0.001). The RFA of the CT gap was successful in 18 patients. Four patients had recurrence of arrhythmias during the follow-up of 11 ± 3 months. CONCLUSIONS Most of the CT conduction gaps were functional and only appeared during ULR. The width of the CT gap was inversely related to the anisotropic ratio of the CT. The RFA of the CT gap was effective in eliminating ULR.

CATHETER ablation, ATRIAL arrhythmias, ATRIAL fibrillation, ARRHYTHMIA, and PROPAFENONE

LIN, Y.-J.,et al.: Electrophysiological Mechanisms and Catheter Ablation of Complex Atrial Arrhythmias from Crista Terminalis: Insight from Three-Dimensional Noncontact Mapping. Paroxysmal atrial fibrillation (PAF) can be initiated by ectopic activation from the crista terminalis. The crista terminalis conduction gap is also a critical isthmus in atrial reentrant arrhythmias like upper and lower loop reentry. The aim of this study was to investigate the mechanism and results of catheter ablation for complex atrial arrhythmias originating from the crista terminalis using the noncontact mapping system (NCM). The study population consisted of six patients (5 men, 1 woman; 70± 9 years) with drug refractory PAF and typical/atypical atrial flutter. NCM identified the earliest ectopic activation originating from the crista terminalis in these six patients. The reentry circuit of atypical atrial flutter propagated around the upper crista terminalis in five patients, and lower crista terminalis in one patient. The reentry circuit of atypical atrial flutter and the initial reentry circuit of AF conducted through the crista terminalis gap in all patients. Radiofrequency applications were delivered on the sites of ectopy, which initiated AF. Substrate modification was also performed over the crista terminalis gap (six patients) and cavotricuspid isthmus (three patients) responsible for the reentry. During a mean follow-up of 9± 5 months (range 5–18 months), five patients were free of AF without antiarrhythmic drugs, and one patient did not have AF or atrial flutter using propafenone. NCM demonstrated the mechanism of crista terminalis ectopy-initiating AF and associated typical/atypical atrial flutter. Catheter ablation of crista terminalis ectopy and substrate for the reentry guided by NCM successfully eliminated these atrial arrhythmias.(PACE 2004; 27:1231–1239) [ABSTRACT FROM AUTHOR]

MUSCLE cells, HAMSTERS as laboratory animals, ION channels, SARCOPLASMIC reticulum, CELLS, and ACTIVE biological transport

1. The present experiments were performed in order to study abnormal action potential configuration and ion channel activity in ventricular myocytes obtained from 23 male myopathic Syrian hamsters (Biobreeders strain 14.6, 32–52 weeks old) compared with 10 age-matched healthy control hamsters (Biobreeders F1B) by means of whole-cell patch-clamp techniques.2. The results show that the myopathic myocytes had a longer action potential duration, a reduced transient outward K+ current on depolarization and a smaller transient inward current on repolarization after prolonged depolarizing pulses (> 500 msec). However, the L-type Ca2+ current and the inwardly rectifing K+ current were not significantly different from those of healthy myocytes.3. The oscillatory transient inward currents could be diminished by treatment with ryanodine (0.01–1 µmol/L), a sarcoplasmic reticulum (SR) Ca2+ release channel blocker, or with Na+-free superfusate.4. We conclude that the hereditary myopathic hamsters are less likely to develop delayed afterdepolarization-related transient inward currents and triggered arrhythmias owing to a smaller SR Ca2+ content. [ABSTRACT FROM AUTHOR]

TACHYCARDIA, ADENOSINES, ADENINE, ARRHYTHMIA, CATHETER ablation, and ELECTROSURGERY

Focal Atrial Tachycardia. Introduction:Adenosine can terminate most focal atrial tachycardias (ATs). However, information about the termination mechanism is limited. This study investigated the effects and mechanism of adenosine on terminating focal AT using a three-dimensional noncontact mapping system.Methods and Results:The study consisted of 7 patients (4 men and 3 women; age 44± 29 years) with focal AT. Cycle length variation and atrial activation pattern at baseline and just before AT termination by adenosine (3–12mg) were analyzed. Noncontact mapping demonstrated focal AT propagated from the origin (O) with preferential conduction and spread away from the breakout sites to the whole atrium. Compared to baseline AT, termination episodes revealed higher mean beat-to-beat variation of AT cycle length (11.7± 11.7 msec vs 4.7± 4.5 msec, P<0.001) and standard deviation of normalized AT cycle length (0.033± 0.014 vs 0.011± 0.005, P<0.001). In termination episodes, adenosine significantly decreased the peak negative voltage of AT-O (–27.2± 15.3%, P<0.01), preferential conduction (proximal:–32.1± 18.7, mid:–28.4± 22.8, distal portion:–29.6± 21.4%, P<0.01), and breakout (–31.4± 12.5%, P<0.01). However, adenosine did not affect voltage in nontermination episodes. Adenosine shifted the locations of AT-O in 5 of 10 AT episodes with termination. Mean number of shifting AT-O was 2.4± 1.5 (range 1–4), with maximum shifting distance of 15.0± 3.1 (range 10–19) mm. Focal activation at AT-O simply disappeared in all termination episodes and therefore was not due to conduction block within preferential conduction or breakout site. Catheter ablation lesions covered 50% of total shifting origins, without late recurrence.Conclusion:Adenosine-induced AT termination was associated with significantly decreased electrogram voltage, shifting AT-O locations, and disappearance of focal activation.(J Cardiovasc Electrophysiol, Vol. 15, pp. 1-7, December 2004) [ABSTRACT FROM AUTHOR]

Anesthesia, intensive care, Anesthésie, réanimation, Cardiology, blood circulation, phlebology, Cardiologie, appareil circulatoire, phlébologie, Pneumology, Pneumologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Pneumologie, Pneumology, Cardiologie. Appareil circulatoire, Cardiology. Vascular system, Coeur, Heart, Trouble du rythme et de la conduction, Cardiac dysrhythmias, Cardiopathie, Heart disease, Cardiopatía, Trouble excitabilité, Excitability disorder, Trastorno excitabilidad, Trouble rythme cardiaque, Arrhythmia, Arritmia, Ablation, Ablación, Anatomie, Anatomy, Anatomía, Appareil circulatoire pathologie, Cardiovascular disease, Aparato circulatorio patología, Appareil respiratoire pathologie, Respiratory disease, Aparato respiratorio patología, Cathéter, Catheter, Catéter, Fibrillation auriculaire, Atrial fibrillation, Fibrilación auricular, Oesophage, Esophagus, Esófago, Oreillette gauche, Left atrium, Orejuela izquierda, ablation, esophagus, and left atrium

Study objectives: Atrioesophageal fistulas have been reported to be a lethal complication following catheter ablation of atrial fibrillation (AF). The purpose of this study was to investigate the relationship between the esophagus and posterior left atrium (LA) and provide the anatomic information necessary to minimize the risk of esophageal injury during AF ablation. Methods and results: Forty-eight patients (43 men; mean ± SD age, 59 ± 12 years) with drug-refractory paroxysmal AF and 32 control subjects (26 men; mean age, 60 ± 9 years) were included. All underwent a CT scan for delineation of the relationship between the esophagus and posterior LA. In the paroxysmal AF group, two major types of esophageal routes were demonstrated. Type 1 routes were found in 42 patients with the lower portion of esophagus close to the ostium of the left inferior pulmonary vein (LIPV), including three subtypes of courses according to the proximity to the left superior pulmonary vein (PV) and LIPV. Type 2 routes were found in six patients with the lower portion of esophagus close to the ostium of the right inferior pulmonary vein (RIPV), including three subtypes of courses according to the proximity to the right superior PV and RIPVs. The mean shortest distance of the esophagus to the four individual PVs significantly differed between type 1 and type 2: 28.4 ± 6.1 mm vs 10.5 ± 5.7 mm (to the right superior), 19.6 ± 7.0 mm vs 3.7 ± 3.4 mm (to the right inferior), 10.1 ± 3.4 mm vs 22.8 ± 4.2 mm (to the left superior), and 2.8 ± 2.5 mm vs 18.7 ± 5.2 mm (to the left inferior), respectively (p < 0.001 for all). Contact of the esophagus and middle part of posterior LA was observed in each patient. However, direct contact of the aorta with the posterior LA wall was more frequent in type 2 than in type 1 (p = 0.001). The clinical characteristics, type of esophageal routes, distance from the esophagus to the four PVs, and diameter of the thoracic cage, LA, and aorta in the control group were similar to those in the AF group (p > 0.05 for all). Conclusion: Although the anatomic relationship between the esophagus and LA posterior wall varied widely, two major patterns of esophageal routes could be depicted. This information is important for deciding the location of the ablation lesions around the PV ostia and LA and for avoiding the potential risk of esophageal injury.

Cardiology, blood circulation, phlebology, Cardiologie, appareil circulatoire, phlébologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Pharmacologie. Traitements medicamenteux, Pharmacology. Drug treatments, Système cardiovasculaire, Cardiovascular system, Vasodilatateurs périphériques. Vasorégulateurs cérébraux, Vasodilator agents. Cerebral vasodilators, Métabolisme général et cellulaire. Vitamines, General and cellular metabolism. Vitamins, Cardiologie. Appareil circulatoire, Cardiology. Vascular system, Vaisseaux sanguins et lymphatiques, Blood and lymphatic vessels, Maladies vasculaires des membres. Pathologie de la veine cave. Maladies vasculaires diverses, Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous, Cardiopathie, Heart disease, Cardiopatía, Trouble excitabilité, Excitability disorder, Trastorno excitabilidad, Trouble rythme cardiaque, Arrhythmia, Arritmia, Ablation, Ablación, Appareil circulatoire pathologie, Cardiovascular disease, Aparato circulatorio patología, Cathéter, Catheter, Catéter, Fibrillation auriculaire, Atrial fibrillation, Fibrilación auricular, Homme, Human, Hombre, Oreillette droite, Right atrium, Orejuela derecha, ablation, atrial fibrillation, and atrium

Background-Catheter ablation of the right atrial (RA) substrate has had variable efficacy in curing paroxysmal atrial fibrillation (PAF), suggesting that RA substrate ablation can play an important role in the treatment of atrial fibrillation (AF) in some patients. The aim of this study was to investigate the electrophysiological characteristics and ablation strategy and its results in a specific group of patients with paroxysmal RA-AF. Methods and Results-The study population consisted of 13 patients (8 men; age, 64± 15 years) with drug-refractory (2± 1 drugs), frequent episodes of PAF. Provocation maneuvers did not reveal any ectopic beat-initiating AF. However, rapid atrial pacing easily induced AF. Activation mapping during sinus rhythm, atrial pacing, and AF was visualized by using a noncontact mapping system. Noncontact mapping revealed RA reentry (6 patients with single-loop circuits and 7 with double-loop circuits) with conduction through channels between lines of block, crista terminalis gaps, and the cavotricuspid isthmus, which could be identified during sinus rhythm and atrial pacing, resulting in fibrillatory conduction in other parts of the RA. The consistency of wavefront activation was confirmed by frequency analysis from equally distributed mapping sites in the RA. Short lines of ablation lesions were aimed at the conduction channels between the lines of block, crista terminalis gaps, and the cavotricuspid isthmus, resulting in bidirectional block. AF was eliminated in 11 (85%) of 13 patients, and those 11 patients with acute success were free of AF without any antiarrhythmic drugs during the long-term follow-up period (16±6 months). Conclusions-RA ablation still can cure selected patients with PAF. Linear ablation of the RA substrate guided by the electrophysiological characteristics of RA-AF is an effective approach for treating this specific group of patients with AF.

Cardiology, blood circulation, phlebology, Cardiologie, appareil circulatoire, phlébologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Cardiologie. Appareil circulatoire, Cardiology. Vascular system, Coeur, Heart, Trouble du rythme et de la conduction, Cardiac dysrhythmias, Appareil circulatoire pathologie, Cardiovascular disease, Aparato circulatorio patología, Cardiopathie, Heart disease, Cardiopatía, Electrodiagnostic, Electrodiagnosis, Electrodiagnóstico, Trouble excitabilité, Excitability disorder, Trastorno excitabilidad, Trouble rythme cardiaque, Arrhythmia, Arritmia, Algorithme, Algorithm, Algoritmo, Appareil circulatoire, Circulatory system, Aparato circulatorio, Cardiologie, Cardiology, Cardiología, Electrocardiographie, Electrocardiography, Electrocardiografía, Flutter auriculaire, Atrial flutter, Flutter auricular, Phlébologie, Phlebology, and Flebología

OBJECTIVES This study was performed to differentiate upper loop re-entry (ULR) from reverse typical atrial flutter (AFL). BACKGROUND Right atrial ULR and reverse typical AFL have different mechanisms and ablation strategies, but similar electrocardiographic characteristics. METHODS This study included 26 patients with reverse typical AFL and 20 patients with ULR. The noncontact mapping system (EnSite-3000, Endocardial Solutions, St. Paul, Minnesota) was used to confirm diagnosis and guide successful radiofrequency ablation. Flutter wave polarity and amplitude in the 12-lead surface electrocardiogram were determined by two independent electrophysiologists. RESULTS The flutter wave polarity in leads I and aVL was significantly different between the reverse typical AFL and ULR groups (p £ 0.001). Voltage measurement revealed significant differences between reverse typical AFL and ULR in leads I, II, aVR, aVF, V1, and V2 (p < 0.001). A new diagnostic algorithm based on negative or isoelectric/flat flutter wave polarity and amplitude ≤0.07 mV in lead I was useful for diagnosis of ULR, with an accuracy of 90% to 97%, a sensitivity of 82% to 100%, and a specificity of 95%. CONCLUSIONS Polarity and voltage measurement of flutter wave in lead I can differentiate reverse typical AFL from ULR.

ENZYMES, HEART atrium, ATRIOVENTRICULAR node, VENTRICULAR tachycardia, ARRHYTHMIA, ELECTRIC properties of heart cells, and CARDIOMYOPATHIES

Right Atrial Substrate of Supraventricular Tachyarrhythmias. Background:Voltage mapping has been used to detect diseased myocardium. However, accurate determination of the local atrial voltage at the same site, and simultaneous recordings from multiple mapping sites were limited. The purpose of this study was to investigate the right atrial (RA) substrate properties in patients with supraventricular tachyarrhythmias (SVT).Methods and Results:Forty patients (aged 55± 20 years) undergoing noncontact mapping and ablation of SVT constituted the study population. There were eight patients with atrioventricular node reentrant tachycardia (AVNRT), eight patients with focal atrial tachycardia (AT), 14 patients with atrial flutter (AFL), and 10 patients with atrial fibrillation (AF). The mean peak negative voltage (PNV) was analyzed in virtual unipolar electrograms, which were obtained from 256 equally distributed RA endocardial sites during sinus rhythm (SR), atrial pacing, and tachycardia. The mean PNV of global RA during SR (−1.34± 0.22 vs.−0.90± 0.40 vs.−1.00± 0.36 vs.−0.85± 0.35 mV, P= 0.04), atrial pacing at cycle lengths of 500 ms (−1.30± 0.29 vs.−0.70± 0.35 vs.−0.76± 0.25 vs.−0.64± 0.26 mV, P= 0.02), and 300 ms (−1.54± 0.47 vs.−0.94± 0.21 vs.−0.75± 0.27 vs.−0.57± 0.22 mV, P<0.01) were significantly greater in patients with AVNRT compared to AT, AFL, and AF. Furthermore, the mean PNV decreased during atrial pacing with shorter pacing cycle length was demonstrated only in patients with AFL and AF.Conclusion:Negative unipolar voltage analysis of global RA showed different RA substrate characteristics during various SVT. The substrate property of activation and cycle length-dependent voltage reduction may be related to the development of AFL and AF.(J Cardiovasc Electrophysiol, Vol. 16, pp. 1-8, March 2005) [ABSTRACT FROM AUTHOR]