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Atrial Electrograms (atrial + electrogram)
Selected AbstractsUsefulness of Interatrial Conduction Time to Distinguish Between Focal Atrial Tachyarrhythmias Originating from the Superior Vena Cava and the Right Superior Pulmonary VeinJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 12 2008KUAN-CHENG CHANG M.D. Objective: Differentiation of the tachycardia originating from the superior vena cava (SVC) or the right superior pulmonary vein (RSPV) is limited by the similar surface P-wave morphology and intraatrial activation pattern during tachycardia. We sought to find a simple method to distinguish between the two tachycardias by analyzing the interatrial conduction time. Methods: Sixteen consecutive patients consisting of 8 with SVC tachycardia and the other 8 with RSPV tachycardia were studied. The interatrial conduction time from the high right atrium (HRA) to the distal coronary sinus (DCS) and the intraatrial conduction time from the HRA to the atrial electrogram at the His bundle region (HIS) were measured during the sinus beat (SR) and during the tachycardia-triggering ectopic atrial premature beat (APB). The differences of interatrial (,[HRA-DCS]SR-APB) and intraatrial (,[HRA-HIS]SR-APB) conduction time between SR and APB were then obtained. Results: The mean ,[HRA-DCS]SR-APB was 1.0 ± 5.2 ms (95% confident interval [CI],3.3,5.3 ms) in SVC tachycardia and 38.5 ± 8.8 ms (95% CI 31.1,45.9 ms) in RSPV tachycardia. The mean ,[HRA-HIS]SR-APB was 1.5 ± 5.3 ms (95% CI ,2.9,5.9 ms) in SVC tachycardia and 19.9 ± 12.0 ms (95% CI 9.9,29.9 ms) in RSPV tachycardia. The difference of ,[HRA-DCS]SR-APB between SVC and RSPV tachycardias was wider than that of ,[HRA-HIS]SR-APB (37.5 ± 9.3 ms vs. 18.4 ± 15.4 ms, P < 0.01). Conclusions: The wide difference of the interatrial conduction time ,[HRA-DCS]SR-APB between SVC and RSPV tachycardias is a useful parameter to distinguish the two tachycardias and may avoid unnecessary atrial transseptal puncture. [source] The VA Relationship After Differential Atrial Overdrive Pacing: A Novel Tool for the Diagnosis of Atrial Tachycardia in the Electrophysiologic LaboratoryJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2007MITSUNORI MARUYAMA M.D. Introduction: Despite recent advances in clinical electrophysiology, diagnosis of atrial tachycardia (AT) originating near Koch's triangle remains challenging. We sought a novel technique for rapid and accurate diagnosis of AT in the electrophysiologic laboratory. Methods: Sixty-two supraventricular tachycardias including 18 ATs (10 ATs arising from near Koch's triangle), 32 atrioventricular nodal reentrant tachycardias (AVNRTs), and 12 orthodromic reciprocating tachycardias (ORTs) were studied. Overdrive pacing during the tachycardia from different atrial sites was performed, and the maximal difference in the postpacing VA intervals (last captured ventricular electrogram to the earliest atrial electrogram of the initial beat after pacing) among the different pacing sites was calculated (delta-VA interval). Results: The delta-VA intervals were >14 ms in all AT patients and <14 ms in all AVNRT/ORT patients, and thus, the delta-VA interval was diagnostic for AT with the sensitivity, specificity, and positive and negative predictive values all being 100%. When the diagnostic value of the delta-VA interval and conventional maneuvers were compared for differentiating AT from atypical AVNRT, both a delta-VA interval >14 ms and "atrial-atrial-ventricular" response after overdrive ventricular pacing during the tachycardia were diagnostic. However, the "atrial-atrial-ventricular" response criterion was available in only 52% of the patients because of poor ventriculoatrial conduction. Conclusions: The delta-VA interval was useful for diagnosing AT irrespective of patient conditions such as ventriculoatrial conduction. [source] Atrial, SA Nodal, and AV Nodal Electrophysiology in Standing Horses: Normal Findings and Electrophysiologic Effects of Quinidine and DiltiazemJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2007Colin C. Schwarzwald Background: Although atrial arrhythmias are clinically important in horses, atrial electrophysiology has been incompletely studied. Hypotheses: Standard electrophysiologic methods can be used to study drug effects in horses. Specifically, the effects of diltiazem on atrioventricular (AV) nodal conduction are rate-dependent and allow control of ventricular response rate during rapid atrial pacing in horses undergoing quinidine treatment. Animals: Fourteen healthy horses. Methods: Arterial blood pressure, surface electrocardiogram, and right atrial electrogram were recorded during sinus rhythm and during programmed electrical stimulation at baseline, after administration of quinidine gluconate (10 mg/kg IV over 30 minutes, n = 7; and 12 mg/kg IV over 5 minutes followed by 5 mg/kg/h constant rate infusion for the remaining duration of the study, n = 7), and after coadministration of diltiazem (0.125 mg/kg IV over 2 minutes repeated every 12 minutes to effect). Results: Quinidine significantly prolonged the atrial effective refractory period, shortened the functional refractory period (FRP) of the AV node, and increased the ventricular response rate during atrial pacing. Diltiazem increased the FRP, controlled ventricular rate in a rate-dependent manner, caused dose-dependent suppression of the sinoatrial node and produced a significant, but well tolerated decrease in blood pressure. Effective doses of diltiazem ranged from 0.125 to 1.125 mg/kg. Conclusions and Clinical Importance: Standard electrophysiologic techniques allow characterization of drug effects in standing horses. Diltiazem is effective for ventricular rate control in this pacing model of supraventricular tachycardia. The use of diltiazem for rate control in horses with atrial fibrillation merits further investigation. [source] Analysis of Atrioventricular Nodal Reentrant Tachycardia with Variable Ventriculoatrial Block: Characteristics of the Upper Common PathwayPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2009KENJI MORIHISA M.D. Background: The precise nature of the upper turnaround part of atrioventricular nodal reentrant tachycardia (AVNRT) is not entirely understood. Methods: In nine patients with AVNRT accompanied by variable ventriculoatrial (VA) conduction block, we examined the electrophysiologic characteristics of its upper common pathway. Results: Tachycardia was induced by atrial burst and/or extrastimulus followed by atrial-His jump, and the earliest atrial electrogram was observed at the His bundle site in all patients. Twelve incidents of VA block: Wenckebach VA block (n = 7), 2:1 VA block (n = 4), and intermittent (n = 1) were observed. In two of seven Wenckebach VA block, the retrograde earliest atrial activation site shifted from the His bundle site to coronary sinus ostium just before VA block. Prolongation of His-His interval occurred during VA block in 11 of 12 incidents. After isoproterenol administration, 1:1 VA conduction resumed in all patients. Catheter ablation at the right inferoparaseptum eliminated antegrade slow pathway conduction and rendered AVNRT noninducible in all patients. Conclusion: Selective elimination of the slow pathway conduction at the inferoparaseptal right atrium may suggest that the subatrial tissue linking the retrograde fast and antegrade slow pathways forms the upper common pathway in AVNRT with VA block. [source] Atrial Electrogram Amplitude and Efficacy of Cavotricuspid Isthmus Ablation for Atrial FlutterPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 9 2003MEHMET OZAYDIN Large atrial electrogram amplitudes recorded in the cavotricuspid isthmus (CTI) may reflect thick atrial musculature. For this reason, in patients with atrial flutter, the efficacy of an application of conventional radiofrequency energy may be related to the amplitude of the local atrial electrogram. In 100 consecutive patients (mean age 59 ± 13 years) with atrial flutter, contiguous applications of radiofrequency energy were delivered in the CTI. The criterion for complete CTI block was the presence of widely split double potentials (>110 ms) along the entire ablation line during pacing from the coronary sinus and posterolateral right atrium. The atrial electrogram amplitude was measured before and after applications of radiofrequency energy at sites of gaps in the ablation line. Complete CTI block was achieved in 90 (90%) of the 100 patients. The mean atrial electrogram amplitudes at gap sites where an application of radiofrequency energy did and did not result in complete block were 0.36 ± 0.42 and 0.67 ± 0.62 mV, respectively (P < 0.01). The positive and negative predictive values (for complete block) of a ,50% decrease in electrogram amplitude after an application of radiofrequency energy were 100% and 35%, respectively. The mean atrial electrogram amplitude is larger at CTI sites where complete isthmus block cannot be achieved with conventional radiofrequency energy. The efficacy of conventional radiofrequency ablation may be improved by identifying areas in the CTI where the voltage is relatively low. (PACE 2003; 26:1859,1863) [source] Characteristics of Complex Fractionated Electrograms in Nonpulmonary Vein Ectopy Initiating Atrial Fibrillation/Atrial TachycardiaJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 12 2009LI-WEI LO M.D. Background: Nonpulmonary vein (PV) ectopy initiating atrial fibrillation (AF)/atrial tachycardia (AT) is not uncommon in patients with AF. The relationship of complex fractionated atrial electrograms (CFAEs) and non-PV ectopy initiating AF/AT has not been assessed. We aimed to characterize the CFAEs in the non-PV ectopy initiating AF/AT. Methods: Twenty-three patients (age 53 ± 11 y/o, 19 males) who underwent a stepwise AF ablation with coexisting PV and non-PV ectopy initiating AF or AT were included. CFAE mapping was applied before and after the PV isolation in both atria by using a real-time NavX electroanatomic mapping system. A CFAE was defined as a fractionation interval (FI) of less than 120 ms over 8-second duration. A continuous CFAE (mostly, an FI < 50 ms) was defined as electrogram fractionation or repetitive rapid activity lasting for more than 8 seconds. Results: All patients (100%) with non-PV ectopy initiating AF or AT demonstrated corresponding continuous CFAEs at the firing foci. There was no significant difference in the FI among the PV ostial or non-PV atrial ectopy or other atrial CFAEs (54.1 ± 5.6, 58.3 ± 11.3, 52.8 ± 5.8 ms, P = 0.12). Ablation targeting those continuous CFAEs terminated the AF and AT and eliminated the non-PV ectopy in all patients (100%). During a follow-up of 7 months, 22% of the patients had an AF recurrence with PV reconnections. There was no recurrence of any ablated non-PV ectopy during the follow-up. Conclusion: The sites of the origin of the non-PV ectopies were at the same location as those of the atrial continuous CFAEs. Those non-PV foci were able to initiate and sustain AF/AT. By limited ablation targeting all atrial continuous CFAEs, the AF could be effectively eliminated. [source] Frequency Analysis of Atrial Electrograms Identifies Conduction Pathways from the Left to the Right Atrium During Atrial Fibrillation,Studies in Two Canine ModelsJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2009KYUNGMOO RYU Ph.D. Studies of atrial fibrillation (AF) have demonstrated that a stable rhythm of very short cycle length in the left atrium (LA) can cause fibrillatory conduction in the rest of the atria. We tested the hypothesis that fast Fourier transform (FFT) analysis of atrial electrograms (AEGs) during this AF will rapidly and reliably identify LA-to-right atrium (RA) conduction pathway(s) generated by the driver. Methods and Results: During induced atrial tachyarrhythmias in the canine sterile pericarditis and rapid ventricular pacing-induced congestive heart failure models, 380,404 AEGs were recorded simultaneously from epicardial electrodes on both atria. FFT analysis of AEGs during AF demonstrated a dominant frequency peak in the LA (driver), and multiple frequency peaks in parts of the LA and the most of the RA. Conduction pathways from the LA driver to the RA varied from study-to-study. They were identified by the presence of multiple frequency peaks with one of the frequency peaks at the same frequency as the driver, and traveled (1) inferior to the inferior vena cava (IVC); (2) between the superior vena cava and the right superior pulmonary vein (RSPV); (3) between the RSPV and the right inferior pulmonary vein (RIPV); (4) between the RIPV and the IVC; and (5) via Bachmann's bundle. Conduction pathways identified by FFT analysis corresponded to the conduction pathways found in classical sequence of activation mapping. Computation time for FFT analysis for each AF episode took less than 5 minutes. Conclusion: FFT analysis allowed rapid and reliable detection of the LA-to-RA conduction pathways in AF generated by a stable and rapid LA driver. [source] Automatic 3D Mapping of Complex Fractionated Atrial Electrograms (CFAE) in Patients with Paroxysmal and Persistent Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2008JINJIN WU M.D. Background: Complex fractionated atrial electrograms (CFAE) are a possible target for atrial fibrillation (AF) ablation and can be visualized in three-dimensional (3D) mapping systems with specialized software. Objective: To use the new CFAE software of CartoXP® (Biosense Webster, Diamond Bar, CA, USA) for analysis of spatial distribution of CFAE in paroxysmal and persistent AF. Methods: We included 16 consecutive patients (6 females; mean 59.3 years) with AF (6 paroxysmal and 10 persistent) undergoing AF ablation. Carto maps of left atrium (LA) were reconstructed. Using the new CFAE software, the degree of local electrogram fractionation was displayed color-coded on the map surface. LA was divided into four regions: anterior wall, inferior wall, septum, and pulmonary veins (PV). The relationship among regions with CFAE visualized and CFAE ablation regions (persistent AF only) was analyzed retrospectively. Results: In paroxysmal and persistent AF, CFAE were observed in all four LA regions. In paroxysmal AF, the density of CFAE around the PV was significantly higher than in other regions (P < 0.05) and higher than in persistent AF (P < 0.05). In persistent AF, CFAE were evenly distributed all over the LA. Of 40 effective ablation sites with significant AF cycle length prolongation, 33 (82.5%) were judged retrospectively by CFAE map as CFAE sites. Conclusion: CFAE software can visualize the spatial distribution of CFAE in AF. CFAE in persistent AF were observed in more regions of LA compared to paroxysmal AF in which CFAE concentrated on the PV. Automatically detected CFAE match well with ablation sites targeted by operators. [source] An Acute Model for Atrial Fibrillation Arising from a Peripheral Atrial Site: Evidence for Primary and Secondary TriggersJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2008BENJAMIN J. SCHERLAG Ph.D. Background: We previously demonstrated that acetylcholine (Ach) injected into cardiac ganglionated plexi (GP) causes pulmonary vein (PV) ectopy initiating atrial fibrillation (AF). Objective: To determine the effects of Ach applied at non-PV sites. Methods: Overall, 54 dogs were anesthetized with Na-pentobarbital. A right and left thoracotomy allowed the placement of multielectrode catheters to record from the superior PVs, mid portion of the atrium and the atrial appendages (AA). A monophasic action potential (MAP) was recorded from the AA. Ach (1, 10, 100 mM) was applied sequentially to the AA. Results: In 19 of 26 animals, Ach 100 mM on the right (n = 15) or left (n = 4) AA induced focal, sustained AF (,10 minutes) with rapid regular firing (cycle length = 37 ± 7 ms) at the AA. A clamp with teeth placed across the AA caused arrest in the AA. However, AF was sustained only when PV sites adjacent to the GP manifested complex fractionated atrial electrograms (CFAE). Clamping the AA prior to Ach (100 mM) application resulted in focal AF arising at the PVs but not at the AA. When a clamp without teeth was applied prior to Ach application, no AF at either AA or PV site could be induced. Conclusion: Isolation of the focal AF at the AA (primary trigger) by clamping caused cessation of activity in the AA, but AF continued due to secondary triggers arising from PVs. The possible mechanism(s) responsible for these findings are discussed, and various ancillary experiments (n = 28) were added to help elucidate mechanisms. [source] Entrainment Mapping of Dual-Loop Macroreentry in Common Atrial Flutter:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2004New Insights into the Atrial Flutter Circuit Introduction: The aim of this study was to determine using entrainment mapping whether the reentrant circuit of common type atrial flutter (AFL) is single loop or dual loop. Methods and Results: In 12 consecutive patients with counterclockwise (CCW) AFL, entrainment mapping was performed with evaluation of atrial electrograms from the tricuspid annulus (TA) and the posterior right atrial (RA) area. We hypothesized that a dual-loop reentry could be surmised from "paradoxical delayed capture" of the proximal part of the circuit having a longer interval from the stimulus to the captured beat compared with the distal part of the circuit. In 6 of 12 patients with CCW AFL, during entrainment from the septal side of the posterior blocking line, the interval from the stimulus to the last captured beat was longer at the RA free wall than at the isthmus position. In these six patients with paradoxical delayed capture, flutter cycle length (FCL) was 227 ± 12 ms and postpacing interval minus FCL was significantly shorter at the posterior blocking line than at the RA free wall (20 ± 11 ms vs 48 ± 33 ms, P < 0.05). In two of these patients, early breakthrough occurred at the lateral TA. A posterior block line was confirmed in all six patients in the sinus venosa area by intracardiac echocardiography. Conclusion: Half of the patients with common type AFL had a dual-loop macroreentrant circuit consisting of an anterior loop (circuit around the TA) and a posterior loop (circuit around the inferior vena cava and the posterior blocking line). (J Cardiovasc Electrophysiol, Vol. 15, pp. 679-685, June 2004) [source] Effect of Electrical and Structural Remodeling on Spatiotemporal Organization in Acute and Persistent Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2002JOSEPH G. AKAR M.D. Spatiotemporal Organization in Atrial Fibrillation.Introduction: Atrial fibrillation (AF) may originate from discrete sites of periodic activity. We studied the effect of structural and electrical remodeling on spatiotemporal organization in acute and persistent AF. Methods and Results: Atrial effective refractory periods (AERPs) were recorded from five different sites at baseline and after pacing in acute AF (n = 8 dogs) and persistent AF (n = 8). Four persistent AF dogs subsequently were cardioverted to sinus rhythm to allow AERP recovery. Periodicity was quantified by calculating power spectra on left atrial electrograms obtained from a 64-electrode basket catheter. Left atrial size was measured by intracardiac echocardiography and structural changes were assessed by electron microscopy. Mean AERPs decreased after pacing in acute (128 ± 16 msec to 108 ± 29 msec, P < 0.001) and persistent AF (135 ± 16 msec to 104 ± 24 msec, P < 0.0001). AERP recovery was established after 7 days of sinus rhythm. Structural changes were mild in acute AF, severe in persistent AF, and remained severe after AERP recovery. A single dominant frequency was identified in 94% of acute AF bipoles, 57% in persistent AF, and 76% after AERP recovery. Average correlation coefficient was 0.82 among acute AF bipoles, 0.63 in persistent AF, and 0.73 after AERP recovery. Conclusion: Transition from acute to persistent AF is associated with loss of spatiotemporal organization. A single dominant frequency recruits the majority of the left atrium in acute AF. Persistent AF, however, is associated with structural remodeling and dominant frequency dispersion. Recovery of refractoriness only partially restores spatiotemporal organization, indicating a major role for structural remodeling in the maintenance of persistent AF. [source] Electrogram Polarity and Cavotricuspid Isthmus Block During Ablation of Typical Atrial FlutterJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2001HIROSHI TADA M.D. Electrogram Polarity in Atrial Flutter Ablation.Introduction: The atrial activation sequence around the tricuspid annulus has been used to assess whether complete block has been achieved across the cavotricuspid isthmus during radiofrequency ablation of typical atrial flutter. However, sometimes the atrial activation sequence does not clearly establish the presence or absence of complete block. The purpose of this study was to determine whether a change in the polarity of atrial electrograms recorded near the ablation line is an accurate indicator of complete isthmus block. Methods and Results: Radiofrequency ablation was performed in 34 men and 10 women (age 60 ± 13 years [mean ± SD]) with isthmus-dependent, counterclockwise atrial flutter. Electrograms were recorded around the tricuspid annulus using a duodecapolar halo catheter. Electrograms recorded from two distal electrode pairs (E1 and E2) positioned just anterior to the ablation line were analyzed during atrial flutter and during coronary sinus pacing, before and after ablation. Complete isthmus block was verified by the presence of widely split double electrograms along the entire ablation line. Complete bidirectional isthmus block was achieved in 39 (89%) of 44 patients. Before ablation, the initial polarity of E1 and E2 was predominantly negative during atrial flutter and predominantly positive during coronary sinus pacing. During incomplete isthmus block, the electrogram polarity became reversed either only at E2, or at neither E1 nor E2. In every patient, the polarity of E1 and E2 became negative during coronary sinus pacing only after complete isthmus block was achieved. In 4 patients (10%), the atrial activation sequence recorded with the halo catheter was consistent with complete isthmus block, but the presence of incomplete block was accurately detected by inspection of the polarity of E1 and E2. Conclusion: Reversal of polarity in bipolar electrograms recorded just anterior to the line of isthmus block during coronary sinus pacing after ablation of atrial flutter is a simple, quick, and accurate indicator of complete isthmus block. [source] Ablation of Atypical Atrial Flutter Guided by the Use of Concealed Entrainment in Patients Without Prior Cardiac SurgeryJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2 2000FRANK BOGUN M.D. Ablation of Atypical Atrial Flutter. Introduction: Mapping techniques have not been systematically evaluated with respect to atypical atrial flutter (AF) not involving the inferior vena cava isthmus. The purpose of this study was to assess prospectively the use of concealed entrainment (CE) in mapping of AF and to assess the clinical benefit of ablation of clinically relevant atypical AF. Methods and Results: In seven consecutive patients without prior cardiac surgery presenting with atypical AF, mapping was performed in the right and, if necessary, left atrium. At sites with CE, radiofrequency energy was delivered. In a posthoc analysis, the endocardial activation time, stimulus-flutter wave (F) interval, presence of split potentials and diastolic potentials, and postpacing Interval were assessed, and effective sites were compared to ineffective sites. A total of 22 forms of atypical AE either could be induced or were present at the time of the study. Eleven of the 13 targeted atypical AFs (85%) were successfully ablated. The positive predictive value of CE increased from 45% to 75% in the presence of matching electrogram-F and stimulus-F intervals or if flutter terminated during entrainment pacing, and to 88% in the presence of split atrial electrograms or diastolic potentials. During short-term clinical follow-up, none of the patients had recurrence of the ablated AE. However, the majority of patients required either medication for atrial fibrillation or repeated interventions for new forms of AF. Conclusion: Mapping and ablation of atypical AF is feasible if sites with CE can be identified. However, the clinical benefit of successful ablations in patients with atypical flutter appears to be limited. [source] | ||||||||||