bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ventricular Filling Slows Epicardial Conduction and Increases Action Potential Duration in an Optical Mapping Study of the Isolated Rabbit Heart
Authors: Sung Derrick , Mills Robert W. , Schettler Jan , Narayan Sanjiv M. , Omens Jeffrey H. , McCulloch Andrew D. 
Published: August 2010

Introduction: Mechanical stimulation can induce electrophysiologic changes in cardiac myocytes, but how mechanoelectric feedback in the intact heart affects action potential propagation remains unclear. Methods and Results: Changes in action potential propagation and repolarization with increased left ventricular end‐diastolic pressure from 0 to 30 mmHg were investigated using optical mapping in isolated perfused rabbit hearts. With respect to 0 mmHg, epicardial strain at 30 mmHg in the anterior left ventricle averaged 0.040 ± 0.004 in the muscle fiber direction and 0.032 ± 0.006 in the cross‐fiber direction. An increase in ventricular loading increased average epicardial activation time by 25%± 3% (P < 0.0001) and correspondingly decreased average apparent surface conduction velocity by 16%± 7% (P = 0.007). Ventricular loading did not significantly alter action potential duration at 20% repolarization (APD20) but did at 80% repolarization (APD80), from 179 ± 7 msec to 207 ± 5 msec (P < 0.0001). The dispersion of APD20 was decreased with loading from 19 ± 2 msec to 13 ± 2 msec (P = 0.024), whereas the dispersion of APD80 was not significantly changed. These electrophysiologic changes with ventricular loading were not affected by the nonspecific stretch‐activated channel blocker streptomycin (200 μM) and were not attributable to changes in myocardial perfusion or the presence of an electromechanical decoupling agent (butanedione monoxime) during optical mapping. Conclusion: Acute loading of the left ventricle of the isolated rabbit heart decreased apparent epicardial conduction velocity and increased action potential duration by a load‐dependent mechanism that may not involve stretch‐activated channels. (J Cardiovasc Electrophysiol, Vol. 14, pp. 739‐749, July 2003)
T‐Type Calcium Current in Electrical Activity of Cardiomyocytes Isolated from Rabbit Pulmonary Vein
Authors: CHEN YAO‐CHANG , CHEN SHIH‐ANN , CHEN YI‐JEN , TAI CHING‐TAI , CHAN PAUL , LIN CHENG‐I 
Published: August 2010

Introduction: Pulmonary veins (PVs) are known to initiate paroxysmal atrial fibrillation. T‐type calcium current (ICa‐T) has a role in normal and abnormal automaticity of cardiomyocytes. The aim of this study was to evaluate whether ICa‐T contributes to PV electrical activity. Methods and Results: By whole‐cell clamp techniques in rabbit myocytes, ICa‐T was identified in 12 (39%) of 31 PV cardiomyocytes with pacemaker activity, 2 (9%) of 23 PV cardiomyocytes without pacemaker activity, and 2 (15%) of 13 atrial myocytes (P < 0.05). Maximum ICa‐L and ICa‐T densities from PV cardiomyocytes with pacemaker activity were 6.87 ± 2.17 pA/pF and 1.38 ± 0.69 pA/pF, respectively. Nickel (40 μM) decreased the spontaneous activity in 5 (36%) of 14 PV cardiomyocytes (3.1 ± 0.6 Hz vs 2.2 ± 0.5 Hz, P < 0.05), reduced the amplitudes of delayed afterdepolarization from 13 ± 1 mV to 7 ± 1 mV (n = 4, P < 0.05) and inhibited transient inward currents from 1.2 ± 0.2 pA/pF to 0.7 ± 0.1 pA/pF (n = 11, P < 0.01). Conclusions: We conclude that ICa‐T contributes to PV pacemaker activity and triggered activity, which are of functional importance in PV arrhythmogenesis. (J Cardiovasc Electrophysiol, Vol. 15, pp. 567‐571, May 2004)
High‐Flow Perfusion of Sheaths for Prevention of Thromboembolic Complications During Complex Catheter Ablation in the Left Atrium
Authors: CAUCHEMEZ BRUNO , EXTRAMIANA FABRICE , CAUCHEMEZ SIMON , COSSON STÉPHANE , ZOUZOU HANANE , MEDDANE MOHAMED , D'ALLONNES LAURE REVAULT , LAVERGNE THOMAS , LEENHARDT ANTOINE , COUMEL PHILIPPE , HOUDART EMMANUEL 
Published: August 2010

Introduction: Mechanisms for thromboembolic complications during complex ablation procedures in left atrium (LA) have not been defined. The aim of this study was to determine the effect of the perfusion rate of the transseptal sheath on the incidence of thromboembolic complications during catheter ablation for atrial fibrillation (AF) or LA macroreentrant tachycardia. Methods and Results: We analyzed clinical and procedural data from 86 consecutive patients (153 procedures) referred for catheter ablation of AF (74 patients) or LA macroreentrant tachycardia (12 patients). The transseptal sheath was continuously perfused at a low flow rate (3 mL/hour) for the first 32 patients and at a high flow rate (180 mL/hour) for the subsequent 54 patients. Ablation was mainly performed using map‐guided isolation of pulmonary veins for AF and three‐dimensional electroanatomic mapping for LA macroreentrant tachycardia. Five patients (6% of patients and 3.5% of procedures) developed a cerebral thromboembolic complication, all during procedures using low‐flow perfusion. Sheath perfusion rate and total procedure duration were the two variables significantly associated with the occurrence of stroke (P = 0.013 and 0.001, respectively). After adjustment in a multivariable analysis, sheath perfusion rate remained the only risk factor for stroke. The risk was 17 times higher using low‐flow than high‐flow perfusion (odds ratio 17.26, 95% confidence interval 1.14–260.81, P = 0.04). No other clinical or procedural parameters had any significant effect. Conclusion: Sheath perfusion rate is an important determinant of the risk factor for stroke during complex LA ablation procedures. Continuous high‐flow perfusion appears to be effective in preventing this complication. (J Cardiovasc Electrophysiol, Vol. 15, pp. 276‐283, March 2004)
Fractionation of Electrograms and Linking of Activation During Pharmacologic Cardioversion of Persistent Atrial Fibrillation in the Goat
Authors: SHAN ZHAOLIANG , VAN DER VOORT PEPIJN H. , BLAAUW YURI , DUYTSCHAEVER MATTIAS , ALLESSIE MAURITS A. 
Published: August 2010

Introduction: During atrial fibrillation (AF), there is fractionation of extracellular potentials due to head‐to‐tail interaction and slow conduction of fibrillation waves. We hypothesized that slowing of the rate of AF by infusion of a Class I drug would increase the degree of organization of AF. Methods and Results: Seven goats were instrumented with 83 epicardial electrodes on the left atrium, left atrial appendage, Bachmann's bundle, right atrium, and right atrial appendage. AF was induced and maintained by an automatic atrial fibrillator. After AF had persisted for 4 weeks, the Class IC drug cibenzoline was infused at a rate of 0.1 mg/kg/min. AF cycle length (AFCL), the percentage of fractionated potentials, conduction velocity (CV), and direction of propagation of the fibrillation waves were measured during baseline, after AFCL was increased by 20, 40, 60, and 80 ms, and shortly before cardioversion. Infusion of cibenzoline increased the mean of the median AFCLs from 96 ± 6 ms to 207 ± 43 ms (P < 0.0001). The temporal variation in AFCL in different parts of the atria was 8% to 20% during control and, with the exception of Bachmann's bundle, was not significantly reduced during cibenzoline infusion. CV decreased from 76 ± 14 ms to 52 ± 9 cm/s (P < 0.01). Cibenzoline increased the percentage of single potentials from 81%± 4% to 91%± 4% (P < 0.01) and decreased the incidence of double potentials from 14%± 4% to 7 ± 5% (P < 0.01) and multiple potentials from 5%±% to 1%± 2% (P < 0.001). Whereas during control, linking (consecutive waves propagating in the same direction) during seven or more beats occurred in 9%± 15% of the cycles, after cibenzoline the degree of linking had increased to 40%± 33% (P < 0.05). During the last two beats before cardioversion, there was a sudden prolongation in AFCL from 209 ± 37 ms to 284 ± 92 ms (P < 0.01) and a strong reduction in fractionated potentials (from 22%± 12% to 6%± 5%, P < 0.05). Conclusion: The Class IC drug cibenzoline causes a decrease in fractionation of fibrillation electrograms and an increase in the degree of linking during AF. This supports the observation that Class I drugs widen the excitable gap during AF. (J Cardiovasc Electrophysiol, Vol. 15, pp. 572‐580, May 2004)
Atrial Activation Mapping in Sinus Rhythm in the Clinical Electrophysiology Laboratory:
Authors: COSÍO FRANCISCO G. , MARTÍN‐PEÑATO ARTURO , PASTOR AGUSTÍN , NÚÑEZ AMBROSIO , MONTERO MARÍA ANTONIA , CANTALE CARINA P. , SCHAMES SALOMAO 
Published: August 2010

Introduction: The high posterolateral right atrium (RA) is considered the “sinus node area,” but we lack information on endocardial atrial activation in sinus rhythm. We studied RA and left atrial (LA) endocardial activation in the electrophysiology laboratory. Methods and Results: Thirty‐five patients (21 men) aged 47 ± 16.4 years (mean ± SD) underwent RA mapping (22.2 ± 3.8 points). In 21 patients, LA activation was mapped (11.1 ± 3.9 points) through the coronary sinus (CS), right pulmonary artery, and/or a patent oval foramen. Fourteen patients had atrial arrhythmias, and 3 an ECG pattern of Bachmann's bundle block. Endocardial RA activation preceded P wave in 5 (–14 ± 4.2 ms), coincided in 11, and followed P onset in 18 (16.7 ± 6.6 ms). Location of the zero point varied from the superior vena cava to the low RA and from lateral to paraseptal RA. In 19 patients, activation started simultaneously in 2 to 5 points located ≥1 cm apart. RA activation was descending in most, but in 3 with low onset there was collision in the anterior and septal walls. In 15 of 21 patients, descending LA activation dominated, ending in the mid CS in 12, proximal CS in 1, and simultaneously throughout the CS in 2. In 3 with Bachmann's bundle block, CS activation was ascending and in 2 double potentials were recorded from the LA roof. Conclusion: During stable sinus rhythm, RA activation can start in different areas or simultaneously over large areas resulting in different activation patterns, both in the RA and the LA. LA activation is predominantly descending, but in Bachmann's bundle block it becomes ascending, and double potentials suggest a location of block in the LA roof. (J Cardiovasc Electrophysiol, Vol. 15, pp. 524‐531, May 2004)
Cryoenergy Catheter Ablation:
Authors: GAITA FIORENZO , ANTONIO MONTEFUSCO , RICCARDI RICCARDO , GIUSTETTO CARLA , GROSSI STEFANO , CARUZZO ENRICO , BIANCHI FRANCESCA , VIVALDA LAURA , GABBARINI FULVIO , CALABRO RAFFAELE 
Published: August 2010

Introduction: Permanent junctional reciprocating tachycardia (PJRT) is an infrequent form of reciprocating tachycardia, almost incessant from childhood and usually refractory to drug therapy. Radiofrequency catheter ablation currently is the first‐line therapy for PJRT, but its application in the septal region may be associated with complications. In contrast, cryoenergy has several advantages, such as the ability to test the effects of ablation while the lesion is still forming, thus reducing the number of ineffective, useless, and potentially harmful lesions. The aim of this study was to investigate the potential clinical utility of percutaneous cryoenergy catheter ablation for treatment of pediatric patients with PJRT. Methods and Results: Four patients (age 14 ± 5 years; mean ± SD) with a clinical diagnosis of PJRT underwent catheter cryoablation. The ablation was successfully accomplished in 4 (100%) of 4 patients. The mean ± SD number of cryoapplications was 1.8 ± 0.8, and from 1 to 6 cryomappings were performed for each permanent cryolesion. The successful site was in the mid‐septal region (2 patients), at the coronary sinus orifice (1 patient), and in the middle cardiac vein (1 patient). No complications with cryoablation were reported, nor was there prolongation of the AH interval during cryomapping or cryoablation. No pain was reported by patients during the cryoenergy catheter ablation procedure. PJRT recurrence occurred in 1 patient who underwent a second successful cryoablation procedure. Conclusion: The outcomes of cryoenergy catheter ablation in these 4 patients treated for PJRT suggest that cryoablation is a safe, effective, and pain‐free technique for treating pediatric patients with PJRT. (J Cardiovasc Electrophysiol, Vol. 15, pp. 263‐268, March 2004)
Misdiagnosis of Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy
Authors: BOMMA CHANDRA , RUTBERG JULIE , TANDRI HARIKRISHNA , NASIR KHURRAM , ROGUIN ARIEL , TICHNELL CRYSTAL , RODRIGUEZ RENE , JAMES CYNTHIA , KASPER EDWARD , SPEVAK PHILIP , BLUEMKE DAVID A. , CALKINS HUGH 
Published: August 2010

Introduction: Diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) has major implications for the management of patients and their first‐degree relatives. Diagnosis is based on a set of criteria proposed by the International Task Force for Cardiomyopathies. We report our experience in providing a re‐evaluation for patients who previously have been diagnosed with ARVD/C. Methods and Results: We studied 89 patients who requested a re‐evaluation for diagnosis of ARVD/C at our center. Each of these patients had been diagnosed with ARVD/C at their initial evaluation. Each patient was re‐evaluated with clinical history, physical examination, and noninvasive testing at our center. Invasive testing, which included electrophysiologic testing, right ventricular angiography, and endomyocardial biopsy, was performed when clinically indicated. Sixty (92%) of the 65 patients who had undergone magnetic resonance imaging (MRI) at an outside institution were reported to have an abnormal MRI consistent with ARVD/C. Among these patients, the only abnormality identified was the qualitative finding of intramyocardial fat/wall thinning in 46 patients. On re‐evaluation, these qualitative findings were not confirmed. None of these 46 patients ultimately were diagnosed with ARVD/C. Among the entire patient group, only 24 (27%) of the 89 patients met the Task Force criteria for ARVD/C. Conclusion: This study demonstrates that the high frequency of “misdiagnosis” of ARVD/C is due to over‐reliance on the presence of intramyocardial fat/wall thinning on MRI, incomplete diagnostic testing, and lack of awareness of the Task Force criteria. Diagnosis of ARVD/C cannot rely solely upon qualitative features on MRI. (J Cardiovasc Electrophysiol, Vol. 15, pp. 300‐306, March 2004)
Activation of the Ca2+‐Activated Nonselective Cation Channel by Diacylglycerol Analogues in Rat Cardiomyocytes
Authors: GUINAMARD ROMAIN , CHATELIER AURÉLIEN , LENFANT JACQUES , BOIS PATRICK 
Published: August 2010

Introduction: Cardiac hypertrophy is associated with changes in electrophysiologic properties due to ionic channel modifications and increases in protein kinase C (PKC) activity and diacylglycerol (DAG) content. These changes may contribute to an increased propensity for arrhythmia. Similar electrophysiologic modifications have been reported in adult rat cardiomyocytes undergoing dedifferentiation in primary culture. Methods and Results: Single‐channel measurements on such cells identified the appearance of a Ca2+‐activated nonselective cation channel (NSCCa) during the dedifferentiation process. The current study investigated the sensitivity of this channel to PKC and DAG analogues. In the cell‐attached configuration, channel conductance was 20.2 pS under physiologic conditions. Perfusion with the DAG analogue 1‐oleoyl‐2‐acetyl‐sn‐glycerol (OAG, 0.1 mM) or the PKC activator phorbol 12‐myristate 13‐acetate (PMA, 0.5 μM) increased the channel normalized open probability (nPo), whereas in the presence of the PKC inhibitor calphostin C (1 μM), only OAG retained this effect. In the inside‐out configuration, perfusion of both DAG analogues OAG (0.1 mM) and 1‐stearoyl‐2‐arachidonoyl‐sn‐glycerol (SAG, 10 μM) on the inside of the membrane increased nPo. These results indicate that DAG regulates the NSCCa channel via both the PKC pathway and by a direct interaction. Conclusion: DAG content, PKC activity, and channel expression increased during hypertrophy. This indicates that the NSCCa channel exhibits high activity in this condition and, therefore, is a candidate for the genesis of arrhythmias in ventricular cardiomyocytes. In addition, regulation of the channel by DAG and PKC contributes to current understanding of the physiologic role of this channel, which shares properties with the cloned TRPM4b channel. (J Cardiovasc Electrophysiol, Vol. 15, pp. 342‐348, March 2004)
Embryonic Conduction Tissue:
Authors: JONGBLOED MONIQUE R.M. , SCHALIJ MARTIN J. , POELMANN ROBERT E. , BLOM NICO A. , FEKKES MADELON L. , WANG ZHIYONG , FISHMAN GLENN I. , GITTENBERGER‐DE GROOT ADRIANA C. 
Published: August 2010

Introduction: The occurrence of arrhythmias in adult patients may arise preferentially in anatomic regions derived from the specialized cardiac conduction system. To examine this hypothesis, we performed a detailed analysis of the developing cardiac conduction system using the recently described CCS‐lacZ transgenic mouse strain. Methods and Results: Transgenic embryos (E9.5–15.5) were stained for β‐galactosidase activity and co‐stained with the myocardial marker HHF35. Results were reconstructed three dimensionally. CCS‐lacZ expression was observed in the sinoatrial node, left and right venous valves, septum spurium, right and left atrioventricular ring, His bundle, bundle branches, and right ventricular moderator band. Furthermore, lacZ‐positive cells could be demonstrated for the first time in the left atrium, in the posterior wall surrounding the pulmonary venous orifice. and, in later stages, surrounding the pulmonary venous wall. These cells were continuous with the left venous valve in the right atrium. LacZ‐positive tissue also could be identified in Bachmann's bundle, running retro‐aortically between the right atrium and left atrium. Conclusion: Known arrhythmogenic areas including Bachmann's bundle, the pulmonary veins, and sinus venosus derived internodal structures, demonstrate lacZ expression. These data support the hypothesis that areas derived from the developing cardiac conduction system may contribute to the arrhythmogenic substrate in adult hearts. (J Cardiovasc Electrophysiol, Vol. 15, pp. 349‐355, March 2004)
Spatial Dispersion of Repolarization is a Key Factor in the Arrhythmogenicity of Long QT Syndrome
Authors: RESTIVO MARK , CAREF EDWARD B. , KOZHEVNIKOV DMITRY O. , EL‐SHERIF NABIL 
Published: August 2010

Introduction: The occurrence of significant spatial dispersion of repolarization in vivo as it relates to the mechanism of arrhythmia formation in the long QT syndrome (LQTS) continues to be questioned. Methods and Results: We investigated a guinea pig model of LQT3 using anthopleurin‐A (AP‐A) to study the contribution of rate‐dependent spatial dispersion of repolarization in the intact heart to the arrhythmogenicity of LQTS. Optical action potentials were measured using potentiometric fluorescent dye di‐4ANEPPS in Langendorff‐perfused hearts with induced AV block. AP‐A exacerbated the normal uniform epicardial apex‐base action potential duration (APD) gradient, resulting in rate‐dependent increased APD dispersion and nonuniform APD gradient. Spontaneous focal premature beats induced functional conduction block along boundaries where large nonuniform APD gradient occurred setting the stage for circulating wavefronts and ventricular tachyarrhythmia (VT). Endocardial ablation abolished spontaneous VT, but nonuniform epicardial APD gradient persisted and could be challenged by a stimulated premature stimulus to induce VT. Conclusion: The study shows that in LQT3, spatial variations in steady‐state properties result in zones of nonuniform APD gradients. These provide a substrate for functional conduction block and reentrant excitation when challenged by subendocardial “early afterdepolarization‐triggered” premature beats. The study emphasizes the key importance of spatial dispersion of repolarization, whether located in epicardial or intramyocardial layers, in arrhythmia formation in LQTS. (J Cardiovasc Electrophysiol, Vol. 15, pp. 323‐331, March 2004)
Efficacy and Safety of Segmental Ostial Versus Circumferential Extra‐Ostial Pulmonary Vein Isolation for Atrial Fibrillation
Authors: MANSOUR MOUSSA , RUSKIN JEREMY , KEANE DAVID 
Published: August 2010

Introduction: Pulmonary vein (PV) isolation for atrial fibrillation (AF) can be performed using a segmental ostial or a circumferential extra‐ostial approach. The relative merits and potential limitations of each approach are currently debated. Here we report our early experience with each of these approaches, including their relative efficacy and safety. Methods and Results: Forty patients with drug‐refractory AF underwent segmental ostial PV isolation and were compared to 40 consecutive patients who underwent PV isolation using a circumferential extra‐ostial approach. The latter approach described here is novel in two aspects: (1) the endpoint for ablation was PV isolation and not only delay in left atrial to PV conduction time, and (2) isolation of the right and left PVs was achieved by a single encirclement of ipsilateral veins. At follow‐up, 60% of the patients in the segmental group were free of AF compared to 75% of the patients in the circumferential group. There was one thromboembolic cerebrovascular complication during the ablation procedure in each group. Conclusion: PV isolation using a circumferential extra‐ostial approach, where the ipsilateral PVs are isolated together by one encircling line of block using electroanatomic mapping, is a technically feasible procedure. This approach is at least as effective and safe as the more established segmental ostial approach for AF ablation. (J Cardiovasc Electrophysiol, Vol. 15, pp. 532‐537, May 2004)
Atrial Fibrillatory Wave Characteristics on Surface Electrogram:
Authors: XI QIN , SAHAKIAN ALAN V. , NG JASON , SWIRYN STEVEN 
Published: August 2010

Introduction: Fibrillatory waves on the surface ECG have been scrutinized to allow inferences about underlying mechanisms and pathophysiology, based on the premise that fibrillatory waves do not vary “randomly” but provide a consistent reflection of the underlying state of the atria in an individual patient. This premise is untested. Methods and Results: Ten standard ECGs were recorded over a 24‐hour period in each of 20 clinically stable inpatients with atrial fibrillation. After QRS‐T cancellation, the remainder fibrillatory waves were analyzed. Interpatient versus intrapatient differences in fibrillatory wave characteristics were evaluated by analysis of variance (ANOVA). The fibrillatory wave peak‐to‐peak amplitude of all the patients ranged from 0.06 to 0.35 mV, whereas 1 SD of the amplitude for each patient ranged from 0.004 to 0.053 mV. Short‐term peak frequencies of all the patients ranged from 4.6 to 8.0 Hz, whereas 1 SD for each patient varied from 0.2 to 0.5 Hz. For these and all other parameters tested, interpatient differences were significantly greater compared to intrapatient differences (P < 0.0001). Conclusion: Fibrillatory wave characteristics are repeatable from ECG to ECG over 24 hours for clinically stable patients, whereas substantial differences are present between patients. Further study of the relationship of such characteristics to pathophysiology and management decisions is valid and warranted. (J Cardiovasc Electrophysiol, Vol. 15, pp. 911‐917, August 2004)