bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transvenous Cold Mapping and Cryoablation of the AV Node in Dogs: Observations of Chronic Lesions and Comparison to Those Obtained Using Radiofrequency Ablation
Authors: RODRIGUEZ LUZ‐MARIA , LEUNISSEN JET , HOEKSTRA AREND , KORTELING BART‐JAN , SMEETS JOEP L.R.M. , TIMMERMANS GARL , VOS MARC , DAEMEN MAT , WELLENS HEIN J.J. 
Published: April 2007

Cryoablation of the Proximal AV Node. Introduction: Radiofrequency (RF) is the most commonly used energy source for the treatment of cardiac arrhythmias. Surgical experience has shown that cryoablation also is effective for ablating arrhythmias. The aims of this study were to (I) investigate the feasibility of inducing permanent complete AV block (CAVB). (2) investigate the value of cold mapping to select the cryoablation site to produce permanent CAVB, (3) study the macro‐ and microscopic lesion characteristics 6 weeks later, and (4) compare them to those produced with RF energy. Methods and Results: A new steerable 8.5‐French bipolar electrode catheter having a thermocouple with a 3‐mm tip using N2O as the refrigerant controlled by a cryoconsole was used. Six mongrel dogs were anesthetized, and the catheter was positioned via the femoral vein across the tricuspid valve to record a large low right atrial and a small His‐bundle potential. After cold mapping (‐15° to ‐20°C tip temperature) resulted in ECG modifications, cryothermia (‐70°C) was given twice, lasting 5 minutes each, to create permanent CAVB (Cryo group). Additionally, RF catheter ablation of the AV node was performed in two anesthetized mongrel dogs (RF group). In the Cryo group, a permanent proximal CAVB was created in four dogs (block occurred within 10 to 20 sec of cryothermia). Permanent right bundle branch block was obtained in one dog and transient CAVB in the remaining dog. In both dogs of the RF group, permanent CAVB was obtained. The cryolesions consisted of well‐circumscribed, homogeneous areas of fibrotic tissue without viable cardiomyocytes. Lesions produced with RF were less circumscribed and inhomogeneous, with clear evidence of viable cardiomyocytes and cartilage formation (patchy lesions). Conclusions: (1) Permanent CAVB can he created by using a steerable cryoablation catheter. (2) Histologically, cryoablated sites were homogeneous and showed fibrotic tissue without signs of chronic inflammation and no evidence of viable myocytes. (3) Lesions created with RF were less homogenous and still contained viable myocytes within the lesion and cartilage formation. (4) The arrhythmogenic significance of these differences requires further study. (5) The technology of using reversible cold mapping has the potential to identify the successful ablation site and warrants further clinical study.
Severe and Early Alteration of Action Potential During Acute Cardiac Rejection in Rats
Authors: BABUTY DOMINIQUE , OJEDA CARLOS , MACHET MARIE‐CHRISTINE , AUPART MICHEL , COSNAY PIERRE , FAUCHIER JEAN‐PAUL , GARNIER DIDIER 
Published: April 2007

Alteration of Cardiac Action Potential. Introduction: Alteration of cardiac action potential and its adaptation to heart rate could contribute to cardiac dysfunction and arrhythmias during acute cardiac rejection. Methods and Results: Heterotopic heart transplantation was performed in allogeneic and syngeneic rats in which the action potentials of right and left ventricles were measured at 1, 2.5, 3.3, and 5.7 Hz successively using standard microelectrode techniques and compared with nontransplanted hearts. For each frequency, we measured action potential amplitude, action potential duration, transmembrane resting potential, and Vmax. In the right ventricle, at 1 Hz in the presence of rejection (n = 40), a significant increase was observed in action potential duration at 20%, 50%, and 70% repolarization (82.5%, 75.6%, and 70.8%, respectively) and in action potential amplitude (+17.9 mV), and the resting potential was decreased (‐5.3 mV). A lack of adaptation of action potential duration to the driving frequency was observed in the rejecting heart group in contrast to controls (n = 20) and nourejecting hearts (n = 13). Similar results were observed in the left ventricle and surprisingly in the native hearts (n = 11) of recipients with allografted rejecting hearts in the abdominal position. Conclusion: Action potential and its adaptation to the driving frequency is considerably altered during acute rejection. A humoral factor could contribute to cardiac dysfunction.
Sinus Tachycardia with Atrioventricular Block:
Authors: SRA JASBIR , SINGH BALBIR , BLANCK ZALMEN , DHALA ANWER , AKHTAR MASOOD 
Published: April 2007

Sinus Tachycardia with AV Block During VVS. Introduction: Neurocardiogenic (vasovagal) syncope is characterized by hypotension and bradycardia. The presence of sinus tachycardia along with AV block during syncope in patients with neurocardiogenic syncope has not been described previously. Methods and Results: Two female patients (18 and 16 years old) with recurrent syncope and documented sinus tachycardia at the time of syncope are described. Patient 1 had recurrent episodes of syncope. During one of these episodes, which occurred while she was being monitored, sinus tachycardia along with high‐grade AV block was seen at the time of syncope and hypotension. Patient 2 had a history of recurrent syncope and seizure. During one of these episodes, she was documented to have ventricular asystole lasting for about 39 seconds. The sinus rate was 480 msec at the beginning, before slowing down to 960 msec prior to restoration of sinus rhythm with 1:1 AV conduction. The same scenario was repeated during head‐up tilt testing. Both patients were treated successfully with oral disopyramide and, during a follow‐up of 28 months and 9 months, have remained symptom‐free. Conclusion: Sinus acceleration along with high‐grade AV block during syncope and hypotension can occur in some patients with neurocardiogenic syncope. The exact mechanism of this phenomenon is unclear.
Influence of Filtering Techniques on the Time‐Domain Analysis of Signal‐Averaged P Wave Electrocardiogram
Authors: VALVBRDE ESTEBAN R. , QUINTEIRO RICARDO A. , BERTRAN GUILLERMO C. , ARINI PEDRO D. , GLENNY PATRICIO , BIAGETTI MARCELO O. 
Published: April 2007

Differences in P Wave Filtering Techniques. introduction: The advent of signal‐averaged ECG (SAECG) systems for P wave analysis has made it important to determine if the use of different filtering techniques in these systems is diagnostically equivalent. Methods and Results: Three different high‐pass filtering techniques and two cutoff frequency values were used: 29‐ and 40‐Hz Butterworth bidirectional filter (BB29, BB40), 29‐and 40‐Hz Butterworth unidirectional filter (UB29, UB40), and 29‐ and 40‐Hz least mean square filter (LIV1S29, LMS40). Normal healthy volunteers (n = 36) and patients with documented paroxysmal atrial fibrillation (n = 23) were analyzed. A custom‐built SAECG system and standard bipolar orthogonal leads were used. Noise was reduced to < 0.3 μV. P wave total duration, root mean square voltage of the terminal 20, 30, and 40 msec of the filtered vector magnitude, and the area under the curve between the onset and offset of averaged unfiltered and filtered P wave vector magnitude were analyzed. Only the duration of the P wave showed statistically significant differences between groups, being longer in the PAF group for all filters and cutoff frequencies studied. A bias increment of ‐20 msec was detected in unidirectional and least mean square filters as compared to the bidirectional filter. Sensitivity, specificity, and predictive accuracy were > 70% for all filters; the BB40 filter yielded the best performance. Conclusion: The normality limits derived from one filter cannot be applied directly to recordings obtained from the other filters. Critical limits must be established individually for different software settings.
Divergent Effect of Acute Ventricular Dilatation on the Electrophysiologic Characteristics of d,I‐Sotalol and Flecainide in the Isolated Rebbit heart
Authors: ECKARDT LARS , HAVERKAMP WILHELM , GOTTKER ULRICH , MADEJA MICHAEL , JOHNA ROBERT , BORGGREFE MARTIN , BREITHARDT GUNTER 
Published: April 2007

Ventricular Dilatation and d,l‐Sotalol/Flecainide in Isolated Rabbit Heart. Introduction: The interaction between acute ventricular dilatation (AVD) as one aspect of ventricular dysfunction and Class I and III antiarrhythmic drugs is uncertain. We therefore investigated the effects of AVD on the electrophysiologic properties of d,l‐sotalol and flecainide. Methods and Results: The isolated rabbit heart was used as a model of AVD. The ventricular size and, therefore, the diastolic pressure were modified by sudden volume changes of a fluid‐filled balloon placed in the left ventricle. Pacing was performed alternately using epi‐ and endocardial monophasic action potential (MAP)‐pacing catheters at cycle lengths from 1,000 to 300 msec. d,l‐Sotalol (10 μM) resulted in a significant (P < 0.05) lengthening of refractoriness (+13.5%± 3.1%), MAP duration (+14.9%± 3.2%), and QT interval (+15.5%± 4.1%) (mean ± SEM at 1,000 msec). These effects had a reverse rate‐dependence. AVD to a diastolic pressure of 30 mmHg reduced refractoriness and left ventricular MAP duration. In comparison with the control group with the same extent of WD, d,l‐sotalol still led to a significant prolongation of repolarization for all cycle lengths except 300 msec, so that its effects were not absolutely but relatively preserved. In contrast, flecainide (2μM) had no significant effects on refractoriness or MAP duration. It led to a significant, rate‐dependent increase of pacing thresholds (+47.6%± 8.2%), prolongation of QRS (+48.8%± 5.6%), and conduction time (+78.6%± 8.6%) (mean ± SEM at 300 msec). In the flecainide group, AVD significantly increased the normal rate‐dependent prolongation of QRS (+16.7%± 5.5%) and conduction time (+17.1%± 4.3%). Conclusion: Our data demonstrate that, during AVD, the Class III effect of d,l‐sotalol is preserved, whereas flecainide's effect of slowing conduction is exaggerated. This may contribute to flecainide‐related proarrhythmia in certain clinical situations.
Functional Communication Between Cardiac ATPSensitive K+ Channel and Na/K ATPase
Authors: TSUCHIYA KUNIHIKO , HORIE MINORU , HARUNA TETSUYA , AI TOMOHIKO , NISHIMOTO TOSHIHISA , FUJIWARA HISAYOSHI , SASAYAMA SHIGETAKE 
Published: April 2007

KATP Channel and Na/K ATPase. Introduction: Functional interaction between KATP channel and Na/K ATPase was studied in single guinea pig ventricular myocytes because both membrane molecules are known to he involved in ischemic episodes. Methods and Results: KATP channel currents were recorded at 36°C by using whole cell, cell attached, inside‐out, and open cell‐attached modes of patch clamp techniques on enzymatically isolated ventricular myocytes. In the whole cell mode, ouabain (1 μM) reversibly inhibited the KATP currents induced by metabolic stress (ATP‐free pipette solution and 1 mM NaCN), but not those activated by cromakalim (100 μM), a KATP channel opener. In the cell‐attached mode, ouabain concentration dependently inhibited KATP, channel opening induced by metabolic suppression (5.5 μM 2‐deoxyglucose and 1 mM CN). Half‐inhibition concentration for ouabain was 21.0 ± 5.5 nM and the Hill coefficient was 0.8 ± 0.1 (n = 26). However, ouabain did not have an effect on the channel activity induced by cromakalim (100 μM). In the inside‐out mode, ouabain applied to the internal side of membrane did not affect the channel. In the open cell‐attached mode made by preincubation with streptolysin‐0 (0.08 U/mL), the KATP channels were not activated by the metabolic inhibitors but were by reducing extracellular ATP concentrations, because subsarcolenimal ATP concentration could he controlled through tiny membrane holes. The channels thus activated were not suppressed by ouabain. Conclusion: The inhibition of Na/K ATPase by ouahain appeared to block the KATP channels by accumulating subsarcolemmal ATP caused by a decrease of the transition from ATP to ADP. In the presence of ischemic episodes, the administration of digitalis compounds may affect the opening of KATP channels, which is primarily protective against the development of irreversible myocardial damage.
Lack of Benefit of Very Short Basic Drive Train Cycle Length or Repetition of Extrastimulus Coupling Intervals for Induction of Ventricular Tachycardia
Authors: LEE CHEE‐STONG , WAN SIU‐HONG , COOPER MARK J. , ROSS DAVID L. 
Published: April 2007

Stimulation Protocol for VT Induction. Introduction: There are considerable variations of uncertain importance in basic drive train cycle lengths and degree of repetition of extrastimuli used in programmed ventricular stimulation protocols in different laboratories. We compare prospectively three different stimulation protocols to examine the influence of a short basic drive train cycle length and repetition of extrastimuli on induction of ventricular tachycardia. Methods and Results: Thirty consecutive patients who had documented ventricular tachycardia or fibrillation based on underlying coronary artery disease underwent programmed ventricular stimulation with each of the three study protocols. Protocol A used a basic drive train cycle length of 400 msec with each extrastimulus coupling interval delivered only once. Protocol B used the same basic drive train cycle length, but with each extrastimulus coupling interval repeated three times before decrementing. Protocol C used 300 msec as the cycle length of basic drive trains without repetition of extrastimuli. Sixty‐three percent, 67%, and 63% of the study patients bad ventricular tachycardia inducible with protocols A, B, and C, respectively (P = NS). Ventricular fibrillation was induced in 23% of the 30 patients in all three protocols. There were no significant differences in the mean cycle lengths of induced ventricular tachycardia, the number of extrastimuli used, and the coupling interval of the last extrastimulus inducing ventricular tachycardia among the three protocols. Conclusion: This study showed no clinical benefit for repetition of extrastimuli that have failed to induce a ventricular tachyarrhythmia during programmed ventricular stimulation. A short basic cycle length of 300 msec was not superior to 400 msec for induction of ventricular tachyarrhythmias. We recommend the use of basic cycle length 400 msec with delivery of each extrastimulus interval only once as the initial protocol for programmed ventricular stimulation.
Antibodies Against Myosin in Sera of Patients with Idiopathic Paroxysmal Atrial Fibrillation
Authors: MAIXENT JEAN‐MICHEL , PAGANELLI FRANCK , SCAGLIONE JORGE , LÉVY SAMUEL 
Published: April 2007

Myosin Antibodies in Atrial Fibrillation. Introduction: Circulating autoantibodies against myosin heavy chain have been detected in patients with ventricular myocarditis and in patients with dilated cardiomyopathy. This study investigated the presence of antibodies against myosin in sera of healthy control persons as compared with patients with idiopathic paroxysmal atrial fibrillation refractory to antiarrhythmic therapy. Methods and Results: An SDS‐PAGK (sodium dodecylsulfate polyacrylamide gel electrophoresis) procedure, followed by Western blotting with homogenates and membrane fractions of human left ventricular and atrial specimen as antigens, was used to analyze sera of 10 patients with idiopathic paroxysmal atrial fibrillation and 10 age‐matched healthy control subjects. Circulating immunoglobulin G reactivity against cardiac myosin heavy chain was detected in 6 patients (60%) as compared with 1 control subject (10%). This difference was statistically significant (P < 0.05). All patients with idiopathic paroxysmal atrial fibrillation who showed reactivity against myosin heavy chain also had specific reactivity in their sera that exhibited reactivities to both ventricular and atrial cardiac myosin heavy chain isoforms. Conclusion: This study demonstrates the presence of circulating autoantibodies against myosin heavy chain in a significant percentage of patients with idiopathic paroxysmal atrial fibrillation and raises the possibility of an autoimmune process in some patients with paroxysmal atrial fibbrillation.
Discrimination of Sinus Rhythm, Atrial Flutter, and Atrial Fibrillation Using Bipolar Endocardial Signals
Authors: JUNG JENS , HOHENBERG GREGOR , HEISEL ARMIN , STRAUSS DANIEL , SCHIEFFER HERMANN , ERIES ROLAND 
Published: April 2007

Discrimination of NSR, AFL, and AF. Introduction: Analysis of endocardial signals obtained from an electrode located in the right atrium as realized in newly designed dual chamber, implantable cardioverter defibrillators might be used to provide additional therapeutic options, such as overdrive pacing or low‐energy atrial cardioversion for the treatment of concomitant atrial flutter (AFL) or atrial fibrillation (AF). Therefore, we developed a computer algorithm for discrimination of normal sinus rhythm (NSR), AFL, and AF that may lead to adequate differential therapy of atrial tachyarrhythmias in an automated mode. Methods and Results: During an electrophysiologic study, bipolar endocardial signals from the high right atrium were obtained in 28 patients during sustained AFL or AF and after restoration of NSR. A total of 286 data segments of 5‐second duration were recorded (NSR: 96, AFL: 86, AF: 104). Mean atrial cycle length (MCL), standard deviation of mean atrial cycle length (SDCK), and index of irregularity (IR). defined as the ratio between MCL and SDCL, were calculated for each data segment. A cutoff of 315 msec for MCL allowed discrimination of NSR from atrial tachyarrhythmias with 100% sensitivity and specificity. For discrimination of AF from AFI‐ by using SDCL, a cutoff value of 11.5 msec led to a sensitivity of 99% and a specificity of 90%. Best discrimination of AF from AFL was found for the criterion IR ≥ 7.5%, resulting in a sensitivity of 100% with a specificity of 95% for AF detection. Conclusion: The investigated algorithm provides discrimination of NSR, AFL, and AF with high sensitivity and specificity. Incorporation of this algorithm in an implantable automated antitachycardia device may lead to adequate differential therapy in patients suffering from spontaneous episodes of AF and AFL.
Organized Activation During Atrial Fibrillation in Man
Authors: ROITHINGER FRANZ X. , Groenewegen ARNE Sippens , KARCH MARTIN R. , STEINER PAUL R. , ELLIS WILLARD S. , LESH MICHAEL D. 
Published: April 2007

Atrial Fibrillation Organization. Introduction: Atrial fibrillation is not entirely random, but little is known about the spatiotemporal endocardial organization and its surface ECG manifestations.Methods and Results: In 16 patients with atrial fibrillation (chronic, n = 14), endocardial mapping of the trabeculated, the posteroseptal smooth right atrium, and the coronary sinus was performed using multipolar catheters. The surface ECG was analyzed by determining “fibrillation wave” (F wave) amplitude, rate, and polarity. During 50 minutes of atrial fibrillation, an organized activation was present 72%± 32% of the analyzed time on the trabeculated, 19%± 15% on the smooth right atrium (P < 0.01), and 51%± 33% along the coronary sinus (P < 0.05). The direction of organized activation was craniocaudal in 72%± 16%. caudocranial in 10%± 9% (P < 0.01), and indeterminable in 18%± 11%. The mean surface F wave amplitude in lead V1 was 0.128 ± 0.06 mV during 28 seconds of atrial fibrillation with a craniocaudal direction of activation and 0.065 ± 0.02 mV during a disorganized activation (P < 0.01). A stable relation between surface F waves and organized trabeculated right atrial activation was observed, and the mean F wave cycle length (190 ± 27 msec) was highly comparable to the simultaneously measured endocardial cycle length (191 ± 27 msec, correlation coefficient 0.97). F wave polarity in V1 was positive in 12 of 14 patients during craniocaudal and negative in 11 of 14 patients during caudocranial rigbt atrial free‐wall activation.Conclusion: An organized activation during atrial fibrillation with a predominant craniocaudal direction on the trabeculated right atrium is frequently present and influences the appearance of “coarse” or “fine” atrial fibrillation as well as F wave polarity on the surface ECG.
Hybrid Pharmacologic and Ablative Therapy: A Novel and Effective Approach for the Management of Atrial Fibrillation
Authors: HUANG DAVID T. , MONAHAN KEVIN M. , ZIMETBAUM PETER , PAPAGEORGIOU PANOGIOTIS , MEPSTEIN LAURENCE , JOSEPHSON MARK E. 
Published: April 2007

Hybrid Therapy for Atrial Fibrillation. Introduction: Maintenance of sinus rhythm in patients with recurrent atrial fibrillation is often difficult to achieve with pharmacologic therapy. Complex catheter ablative procedures are being developed, but efficacy and safety issues remain to be clarified. We hypothesized that combined pharmacologic and simple ablative therapies in a targeted subset of patients will improve success in the treatment of atrial fibrillation.Methods and Results: We identified 13 patients (mean age 61.5 ± 16.2 years) with atrial fibrillation who converted to electrocardiographic atrial flutter during antiarrhythmic drug treatment. Surface ECG suggested “typical” atrial flutter in 11 patients and “atypical” atrial flutter in 2. Intracardiac mapping and entrainment studies revealed 9 patients had counter‐clockwise isthmus‐dependent atrial flutter, and the remaining 4 had complex activation patterns, suggesting the presence of multiple wavefronts. All 9 patients with typical atrial flutter underwent successful ablation. None of the 4 patients with complex activation patterns had successful ablation. Patients were followed for recurrences of atrial arrhythmias via clinic visits, record review, and interviews. In patients who underwent successful ablation and continued on antiarrhythmic drugs, 88.9% remain in sinus rhythm after a mean follow‐up of 14.3 ± 6.9 months (range 1 to 28).Conclusion: In patients who experience conversion of atrial fibrillation to atrial flutter during antiarrhythmic drug treatment, ablation and continuation of pharmacologic therapy is a safe and effective means of achieving and maintaining sinus rhythm.
Atrioventricular Nodal Reentry Tachycardia in Patients with Sinus Node Dysfunction: Electrophysiologic Characteristics, Clinical Presentation, and Results of Slow Pathway Ablation
Authors: KREINER GERHARD , FREY BERNHARD , GÖSSINGER HEINZ DAVID 
Published: April 2007

AVNRT and Sinus Node Dysfunction. Introduction: Sinus node dysfunction (SND) is frequently associated with impaired AV conduction. This study investigated the electrophysiologic properties of dual AV nodal pathways in patients suffering from both SND and AV nodal reentrant tachycardia (AVNRT).Methods and Results: Two groups of patients with slow‐fast AVNRT underwent invasive electrophysiologic testing and catheter ablation of the slow pathway. Group A comprised 10 patients with SND (age 70 ± 8 years), (Group B included 10 age‐matched patients without SND (age 69 ± 7 years; P = NS) who served as controls. Patients of group A exhibited prolongation of the anterograde Wenckebach cycle lengths (WBCLs) of both the fast pathway (559 ± 96 vs 361 ± 38 msec; P < 0.01) and the slow pathway (409 ± 57 vs 339 ± 32 ms; P < 0.01). However, the delta between the WBCLs of the fast and the slow pathways was larger in patients of group A (150 ± 80 vs 22 ± 20 msec; P < 0.01). Retrograde fast pathway conduction was well preserved with no difference in WBCLs (356 ± 42 vs 330 ± 47 msec; P = NS). Cycle lengths of AVNRT were longer in group A (468 ± 46 vs 363 ± 37 msec; P < 0.01). Clinically, all patients of group A suffered from multiple episodes of AVNRT per week, which was not the case in any patient of group B (P < 0.01). Catheter ablation of the slow pathway eliminated AVNRT in all patients without complications.Conclusions: Patients with AVNRT and SND exhibit characteristic electrophysiologic alterations of both AV nodal pathways. Clinically, this results in significantly more frequent episodes of tachycardia. Slow pathway ablation appears to be safe and effective in these patients.