Search

Comparisons between remote magnetic (RMN) and manual catheter navigation for atrial fibrillation (AF) ablation have earlier been reported with controversial results. However, these reports were based on earlier generations of the RMN system.To evaluate the outcomes of the most current RMN system for AF ablation in a larger patient population with longer follow-up time, 112 patients with AF (78 paroxysmal, 34 persistent) who underwent AF ablation utilizing RMN (RMN group) were compared to 102 AF ablation patients (72 paroxysmal, 30 persistent) utilizing manual technique (Manual group).The RMN group was associated with significantly shorter fluoroscopy time (10.4 ± 6.4 vs. 16.3 ± 10.9 min, p .001) but used more RF energy (64.1 ± 19.4KJ vs. 54.3 ± 24.1 KJ, p .05), while total procedure time showed no significant difference (201 ± 35 vs. 196 ± 44 min, NS). After 39 ± 9/44 ± 10 months of follow-up, AF-free rates at 1year, 2 years and 3.5 years post ablation were 63%, 46% and 42% in the RMN group vs. 60%, 32% and 30% (survival analysis p .05) in the Manual group, whereas clinically effective rates were 82%, 73% and 70% for the former vs. 70%, 56% and 49% for the latter (survival analysis p .005).Differing from previous reports, our data from a larger patient population and longer follow-up time demonstrates that compared to manual technique, the most current RMN technique is associated with better procedural and clinical outcomes for AF ablation.

To verify and re-emphasise the efficacy of the max electrogram-guided approach for ablation of cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL).Consecutive patients were alternatively assigned to receive either conventional linear radio-frequency (RF) ablation between the tricuspid annulus and inferior vena cava (the linear approach) or RF ablation at sites with the highest electrograms (the max electrogram-guided approach). Sustained, bi-directional CTI block was the endpoint. Procedure parameters and follow-up data were obtained.In total, 80 patients were included, 40 each for the linear approach and the max electrogram-guided approach. To achieve sustained bi-directional CTI block, the linear approach needed 841 ± 594 sec or 14.0 ± 9.9 RF applications, with total fluoroscopy time of 18.6 ± 9.4 min and total procedure time of 152 ± 58 min, as compared to the max electrogram-guided approach which needed 350 ± 319 sec (p0.0001) or 5.8 ± 5.3 RF applications (p0.0001), with total fluoroscopy time of 14.8 ± 6.0 min (p0.05) and total procedure time of 111 ± 36 min (p0.0005). The CTI block was obtained with 3 or less RF applications in 18 patients in the max electrogram-guided group (45%), but only in 2 patients in the linear ablation group (5%). During follow-up of 28 ± 14 months, recurrence cases were 2 in the linear and 1 in the max electrogram-guided group (NS).During ablation of AFL, directly targeting muscle bundles in the CTI as guided by the highest electrograms is more efficient than making a linear lesion across the entire CTI, since using the former approach needed less RF application, shorter fluoroscopy and procedure times than using the latter. The max electrogram-guided approach may be recommended for routine clinical use to replace the conventional linear ablation approach.

Andersen-Tawil syndrome (ATS) is a rare inherited multisystem disorder associated with mutations in KCNJ2 and low prevalence of life-threatening ventricular arrhythmias. Our aim was to describe the clinical course of ATS in a family, in which the proband survived aborted cardiac arrest (ACA) and genetic screening revealed a previously unknown mutation (c.271_282del12[p.Ala91_Leu94del]) in the KCNJ2 gene.

Background Pulmonary vein (PV) potentials are invariably recordable at the PV ostia in patients with atrial fibrillation (AF) and delayed conduction around the PV ostia may play a role in the initiation and maintenance of AF. Aims To investigate the presence and extent of PV potentials in patients with and without AF. Methods and results Circumferential catheter recordings at the PV ostia were obtained from 10 patients with paroxysmal AF and 9 with concealed Wolff-Parkinson-White (WPW) syndrome without history of AF. Typical PV potential was defined as either rapid deflections that separated from atrial deflection with a time delay in-between, or multiphasic, continuous or fractionated potentials. The presence of PV potentials was verified during sinus rhythm and during atrial pacing at the distal coronary sinus for the left PVs or at the right atrial appendage for the right PVs. To quantify the extent in which the PV potentials were recordable, the number of PVs with typical PV potentials recordable was counted. The time interval from the onset to the end of the electrograms recordable at the PV ostium (A-PV interval) was measured, and the maximal and mean of this interval were obtained. Typical PV potentials were recorded in 31 of 34 PVs (91%) in patients with AF, but in 4 of 36 PVs (11%) in patients with concealed WPW. A narrow, biphsic or triphasic, potential was recorded in 3 of 34 PVs (9%) in patients with AF, but in 29 of 36 (81%) PVs in patients with concealed WPW. The maximal and mean A-PV intervals were significantly longer in patients with AF (71 +/- 24 and 49 +/- 13 ms) than in patients with concealed WPW syndrome (33 +/- 14 and 25 +/- 6 ms). Conclusion In patients with AF, typical PV potentials with marked conduction time delay were almost invariably recordable at the PV ostium, but in patients without a history of AF, merely simple, narrow potentials were found. These findings support the involvement of conduction delay and re-entrant activities around the PV ostia in the genesis and/or perpetuation of AF.

Objectives. To investigate the total dispersion of ventricular repolarization of the epi- and endocardium. Design. Monophasic action potentials (MAP) were recorded from 211 +/- 54 (151-353) left and right ventricular epi- and endocardial sites during atrial pacing in 10 pigs using the CARTO system. The activation time (AT), MAP duration (MAPd) and end of repolarization time (EOR) were measured. Results. The total dispersion of AT, EOR and MAPd, defined as the maximal differences of these parameters over both the epi- and endocardium, were 57 +/- 10, 84 +/- 20, and 75 +/- 21 ms respectively and were significantly larger than the respective epi- and endocardial dispersions (p < 0.05). The epicardial dispersion of AT, EOR and MAPd of both the right and left ventricles were significantly larger than that of each ventricle alone (p < 0.02). Sternotomy did not affect these dispersion parameters. Conclusion. Detailed mapping of epicardial repolarization in vivo using the MAP mapping technique is feasible. Both the epi- and endocardium of the two ventricles contribute significantly to the total dispersion of repolarization. (Less)

AV Nodal Duality and Concealment. Introduction: Both concealed conduction and dual pathway physiology are important electrophysiologic characteristics of the AV node. The interaction of AV nodal concealment and duality, however, is not clearly understood. Methods and Results: The properties of AV conduction curves in the presence and absence of a conditioning blocked impulse were prospectively studied during premature atrial stimulation in 20 patients with AV nodal reentrant tachycardia before and after slow pathway ablation and in 14 control patients. AV nodal duality in the control conduction curve in the absence of a conditioning impulse was observed in 19 (95%) of 20 patients with AV nodal reentrant tachycardia. However, AV nodal duality in the modulated conduction curve in the presence of a blocked impulse was only identified in 2 (10%) of 20 patients (2/20 vs 19/20, P < 0.0001). The modulated curve was characterized by a significantly longer AV nodal effective and functional refractory periods compared to the control curve (P < 0.0001) in both patients with and without AV nodal reentry and in AV nodal reentry patients after successful slow pathway ablation. The maximum AH interval (AH(max)) of the modulated curve was significantly shorter than the control curve in both patients with (217 +/- 74 ms vs 347 +/- 55 ms, P < 0.0001) and without AV nodal reentry (178 +/- 50 ms vs 214 +/- 54 ms, P = 0.02). AH(max) of the control curve was significantly longer in AV nodal reentry patients than in controls (P < 0.0001). AH(max) of the modulated curve, however, was not significantly different between the two groups. After slow pathway ablation, AHmax of the control curve was significantly reduced (347 +/- 55 ms vs 191 +/- 40 ms, P < 0.0001). Significant reduction in AH(max) of the modulated curve was not observed. Conclusion: An interaction of AV nodal concealed conduction and dual pathway physiology was demonstrated by our data. Slow pathway conduction of the AV node was prevented by the concealed beat in both patients with and without AV nodal reentry.

An association between atrial flutter and atrioventricular nodal reentrant tachycardia (AVNRT) has been observed, but the underlying mechanisms are poorly defined. This issue was therefore investigated by comparing the electrophysiological properties of AVNRT patients with and without inducible atrial flutter and those of patients with a history of flutter. Twenty-nine patients with clinically documented atrial flutter and 104 with AVNRT were studied. Atrial flutter was induced in 38 (37%) AVNRT patients during standardized electrophysiological testing before radiofrequency ablation. The atrial relative refractory periods in AVNRT patients with inducible flutter (260 +/- 30 ms) were significantly shorter than those of either patients with a history of flutter (282 +/- 30 ms; P = 0.02) or AVNRT patients without inducible flutter (284 +/- 38 ms; P = 0.006). The atrial effective refractory periods in AVNRT patients with inducible flutter (205 +/- 31 ms) were shorter than in AVNRT patients without inducible flutter (227 +/- 40 ms; P = 0.01). The maximum AH interval during premature atrial stimulation in patients with clinical flutter (239 +/- 94 ms) was shorter than in AVNRT patients either with (290 +/- 91 ms; P = 0.04) or without inducible flutter (313 +/- 101 ms; P = 0.002). However, no significant differences were found in the maximum AH interval achieved during incremental atrial pacing among different groups. Our data show that a non-clinical flutter could more often be induced in those who had short atrial refractoriness. Despite their anatomical proximity, the slow pathway conduction of AVNRT and the isthmus slow conduction of flutter may be related to different mechanisms.

The aim of the study was to explore the global sequence of atrial repolarization and its correlation to that of activation. Endocardial monophasic action potentials (MAPs) were sequentially recorded from 51 +/- 14 sites in the right atrium of ten healthy pigs using the CARTO electroanatomic mapping system. Local activation time (AT), MAP duration, and 90% repolarization time (RT) were obtained, and from these data, color coded three-dimensional maps of AT and RT sequences and spatial distribution of MAP duration were reconstructed. The results of the study were: (1) An activation sequence was recognizable in all maps, starting from the posterosuperior wall and ending in the posteroinferior wall near the tricuspid annulus. (2) The repolarization sequence was also recognizable in all maps, and mainly followed the sequence of activation. (3) A significant positive correlation between the RT and AT was observed in all maps with an average r value being 0.571 +/- 0.159 (P < 0.01 - 0.0001), suggesting that progressively later AT associates with progressively longer RT. (4) No consistent correlation between the MAP duration and AT was found. In conclusion, repolarization gradients exist over the atrial endocardium in healthy pigs. The repolarization sequence follows the same sequence as the activation, suggesting that the spatiotemporal pattern of activation is an important determinant of the characteristics of the repolarization sequence.

Objective - To investigate the feasibility of monophasic action potential ( MAP) mapping using an electro-anatomical mapping system ( CARTO) in obtaining information on global dispersion of atrial repolarization and to evaluate the role of dispersion of repolarization in the genesis of paroxysmal atrial fibrillation ( PAF). Methods and results - Right atrial MAPs were recorded from 53 +/- 18 sites in 10 healthy pigs and 33 +/- 21 sites in 6 patients with and 4 patients without history of PAF. In pigs, the global dispersions of activation time ( AT), MAP duration and end of repolarization time ( EOR), 70 +/- 8, 95 +/- 18 and 121 +/- 28 ms, respectively, were significantly greater than those among 10, 20 and 30 sites. In patients with PAF, the global dispersions of MAP duration and EOR ( 128 +/- 10 and 149 +/- 31 ms) were significantly greater than those in patients without PAF ( 84 +/- 10 and 91 +/- 17 ms). Conclusion - MAP mapping using the CARTO system was feasible in experimental and clinical settings in obtaining information on global dispersion of atrial repolarization. The number of recording sites could significantly affect repolarization parameters. The dispersions of atrial repolarization were significantly greater in patients with PAF than those without, suggesting the involvement of an increased dispersion of repolarization in the genesis of PAF.

This article studies the role of dispersion of atrial refractoriness (DAR) in the genesis of atrial fibrillation (AF). A 20-polar Halo catheter or a 40-polar basket catheter was placed in the right atrium and a 10-polar catheter in the coronary sinus in 21 patients with paroxysmal AF. Bipolar electrograms during AF were recorded from 7 to 16 sites in both atria. As control, electrograms during AF induced by extra-stimulation or burst pacing were also recorded from 4 to 14 sites in both atria in 12 patients with supraventricular tachycardias but without history of AF. The local atrial fibrillation intervals (AFI) during a period of 10 s or 20 s were measured and the mean, median and the 5th, 10th and 15th percentile AFIs at each site were calculated as estimates of the local effective refractory period (AERP). The maximum dispersion and variance of the estimated AERP among the 7-16/4-14 sites were used as measures of the DAR. The maximum dispersion and variance of the 5th and 10th percentile AFIs were significantly greater in the AF group than those in the control group, which were mainly due to the shortening of the minimum 5th and 10th percentile AFIs. No significant differences in dispersion and variance of the mean and median AFIs were shown between the 2 groups. The dispersion and variance of atrial refractoriness during AF estimated from the measurement of short AFIs were significantly greater in patients with paroxysmal AF than in those without clinical AF. The increased dispersion of refractoriness in patients with AF was mainly due to the shortening of the minimum AFIs. These findings suggest the involvement of an increased dispersion of atrial refractoriness in the genesis of paroxysmal AF.

During the last 10-15 years, the implantable cardioverter-defibrillator (ICD) has become an important mode of treatment for patients suffering from grave ventricular arrhythmias, but ICD implantation involves psychosocial adjustments for both patients and relatives. The aim of this pilot study was to design a plan of education and to follow a selected group of patients with interviews, observations, and a questionnaire. The goals included seeing how well they accepted their situation after the operation when they had ongoing support of the nurse, in comparison to a control group who received conventional patient education by the physician. The patients were randomly allocated into two groups. Twenty patients were recruited, 10 in the study group and 10 in the control group, between February, 1997 and April, 1998. There were 16 men (average age, 63) and four women (average age, 57). The Nottingham Health Profile was used to measure health-related quality of life. Sleep disturbances were the greatest problem in both the study group and the control group before ICD implantation. In the study group, there was a significant improvement (p

Experimental studies have shown that remodelling of the atrial myocardium is linked to the occurrence and perpetuation of atrial fibrillation (AF). Clinical evidence, however, is insufficient. We recorded monophasic action potentials (MAP) during AF from one to three sites in the right atrium in seven patients with chronic AF (CAF) and in 11 patients with paroxysmal AF (PAF). The fibrillatory (FF) interval between two consecutive upstrokes of the MAP was measured using a computer-assisted manual method. The mean, median, 15th, 10th, 5th percentile and shortest FF intervals were calculated in each patient and used as estimates of the local atrial effective refractory period (AERP) during AF. In three patients burst pacing at 400 and 500 beats min(-1) was delivered during the MAP recording. In nine patients, the AERP was also tested using the extra stimulus technique during sinus rhythm. RESULTS: Thirty-eight recordings were obtained. The shortest FF interval was significantly shorter in patients with CAF as compared with that in patients with PAF (50+/-13 vs. 72+/-31 ms, P

To study the role of the dispersion of atrial repolarization (DAR) in the genesis of atrial fibrillation (AF), monophasic action potentials (MAP) were recorded simultaneously from a catheter at the high lateral right atrium (HLRA) and a catheter moving around the high, middle and low lateral right atrium (RA) the high, anterior and posterior septal RA and the RA appendage in 15 patients with paroxysmal AF and 15 patients with atrioventricular nodal re-entry tachycardia (AVNRT) or concealed Wolff-Parkinson-White syndrome (WPW) without history of AF. After recordings during sinus rhythm (SR), MAPs were recorded during programmed stimulation (PS) via the HLRA catheter at a drive cycle length (CL) of 500 ms. Thus, MAPs were recorded simultaneously from 2 sites at a time and sequentially from 4 to 12 sites during SR, drive pacing and PS. Taking the MAP at the HLRA as reference, the dispersion of repolarization time (dispersion of RT) and its two components, the dispersions of activation time (dispersion of AT) and MAP duration (dispersion of MAP duration) among the 4 to 12 sites were calculated and taken as parameters of DAR. RESULTS: During SR and PS, the maximal dispersion of RT was significantly greater in AF than in control patients, 113+/-49 ms vs 50+/-28 ms (P

The relation between the atrioventricular conduction properties of the atrioventricular node and the anterograde conduction ability over the accessory pathway in the Wolff-Parkinson-White syndrome has never been studied. Atrioventricular nodal characteristics were studied in 285 patients with manifest and 204 with concealed accessory pathway who underwent radiofrequency ablation, and compared with 146 controls. First and second degree atrioventricular block was observed in 13 (5%) preexcitation patients after ablation, compared with none in concealed accessory pathway (P=0.001) and control patients (P=0.006). The atrial-His intervals in preexcitation patients (88 +/- 20 ms) was significantly longer than in concealed accessory pathway (76 +/- 15 ms, P

Comparisons between remote magnetic navigation (RMN) and manual catheter navigation (Manual) for ablation of atrial fibrillation (AF) have earlier been reported with controversial results. We aim to compare the efficacy and outcome of these two methods for AF ablation based on our data from a larger

Objectives. To establish a set of reference values for regional dispersion of repolarization of the right atrium in the in situ heart of pigs and to see if the global dispersion of repolarization could be estimated from regional mapping. Design. Monophasic action potential (MAP) were sequentially recorded from 28 ± 3 sites in seven different regional areas of the right atrium: lateral, anterior and posterior wall, septum, sinoatrial node (SAN), appendage, and near the tricuspid annulus (TA) in 10 healthy pigs using the CARTO mapping system. Results. The activation time (AT), MAP duration (MAPd) and end of repolarization time (EOR) of the whole right atrium were 68 ± 7, 239 ± 20 and 270 ± 23 ms, respectively. There were no significant differences on MAPd and EOR among the seven regional areas, nor between each of the regional and global values. The global dispersions of the MAPd and EOR were 75 ± 19 and 103 ± 13 ms, which were significantly greater than those obtained from any of the seven regional areas and those between two remote regions, SAN vs. TA and SAN vs. appendage regions. Conclusions. The data of regional and global dispersion of repolarization in healthy pigs can serve as reference values for evaluation of increased dispersion of repolarization. The global dispersions of MAPd and EOR in the right atrium were poorly estimated from regional mapping, suggesting the importance of global mapping in evaluating the dispersion of atrial repolarization.

The purpose of this study was to analyze the velocities across the coronary sinus ostium (cross-CSo) and within the coronary sinus (intra-CS) in patients with and without paroxysmal atrial (AF) fibrillation and to estimate the interatrial conduction deterioration area in AF patients.Interatrial conduction delay in AF patients has been reported. However, localization of the interatrial conduction delay still is not clear.Thirteen patients with paroxysmal AF and 10 control patients with AV nodal reentrant tachycardia or ectopic atrial tachycardia were enrolled in the study. Right atrial and CS mapping were performed using the CARTO electroanatomic mapping system during sinus rhythm and during distal CS pacing. The activation times and spatial distances of cross-CSo and intra-CS were measured between paired sites, from which the activation velocities of cross-CSo and intra-CS were obtained.During sinus rhythm, the activation velocities of cross-CSo in the AF group (1.2 +/- 0.2 m/s) were significantly slower than those in the control group (2.9 +/- 1.6 m/s, P.05). During distal CS pacing, the cross-CSo velocities of the AF group (1.0 +/- 0.5 m/s) also appeared slower than those in the control group (1.4 +/- 0.2 m/s, P = .07). However, no difference was found in intra-CS activation velocities between the two groups (2.8 +/- 1.9 vs 3.2 +/- 2.2 m/s and 1.5 +/- 0.3 vs 1.4 +/- 0.3 m/s, P.05 during sinus rhythm and distal CS pacing, respectively).Interatrial conduction at the posteroparaseptal region across the CS ostium was significantly slower in patients with paroxysmal AF than in control patients, further supporting the link between interatrial conduction deterioration and paroxysmal AF.

Background Local ventricular refractoriness and its dispersion during ventricular fibrillation (VF) have not been well evaluated, due to methodological difficulties. Methods In this study, a non-invasive method was used in evaluation of local ventricular refractoriness and its dispersion during induced VF in 11 patients with VF and/or polymorphic ventricular tachycardia (VT) who have implanted an implantable cardioverter defibrillator (ICD). Bipolar electrograms were simultaneously recorded from the lower oesophagus behind the posterior left ventricle (LV) via an oesophageal electrode and from the right ventricular (RV) apex via telemetry from the implanted ICD. VF intervals were used as an estimate of the ventricular effective refractory period (VERP). In 6 patients, VERP was also measured during sinus rhythm at the RV apex and outflow tract (RVOT) using conventional extra stimulus technique. Results Electrograms recorded from the RV apex and the lower esophagus behind the posterior LV manifested distinct differences of the local ventricular activities. The estimated VERPs during induced VF in the RV apex were significantly shorter than that measured during sinus rhythm using extra stimulus technique. The maximal dispersion of the estimated VERPs during induced VF between the RV apex and posterior LV was that of 10 percentile VF interval (40 ± 27 ms), that is markedly greater than the previously reported dispersion of ventricular repolarization without malignant ventricular arrhythmias (30–36 ms). Conclusions This study verified the feasibility of recording local ventricular activities via oesophageal electrode and via telemetry from an implanted ICD and the usefulness of VF intervals obtained using this non-invasive technique in evaluation of the dispersion of refractoriness in patients with ICD implantation.

Objective—To delineate the electrophysiological properties of transseptal conduction from the left to the right atrium in patients with paroxysmal atrial fibrillation (AF). Design and results—Right atrial mapping using the electroanatomic mapping technique was performed at 111 ± 16 sites in 16 patients with paroxysmal AF during pacing from distal coronary sinus (CS). A single transseptal breakthrough near the CS ostium was observed in all patients. The activation time from the pacing site to the earliest septal activation site was 47 ± 13 ms. The total septal activation time (68 ± 16 ms) was markedly longer but the total right atrial activation time (118 ± 17 ms) was similar to that in patients without AF in a previous observation. Conclusion—During distal CS pacing, a preferential site of transseptal conduction near the CS ostium was demonstrated in patients with paroxysmal AF. This has clinical implications when surgical dissection or catheter ablation is considered to eliminate interatrial connection i...

Inter-atrial conduction delay in patients with atrial fibrillation (AF) has been reported. However, the area of this conduction delay has not been well identified. The activation time and conduction velocity over the right atrial endocardium were evaluated during sinus rhythm using the CARTO mapping technique in 6 patients with paroxysmal AF (AF group) and 11 patients without history of AF (control group). No significant differences were observed between the 2 groups in the mean activation times and conduction velocities from the earliest activation site to the superior septum, His bundle area and coronary sinus ostium, or in the total activation times of the right atrium. There was no significant difference between the two groups in the local conduction velocity between 2 adjacent sites in the free wall, septum and bottom of the right atrium. This study suggests the previously reported conduction delay in the posteroseptal region in patients with paroxysmal AF might locate within the posterior inter-atrial septum.

The trigger mechanism of paroxysmal atrial fibrillation is usually an atrial ectopic beat originating in the muscular sleeves of the pulmonary veins. These and other origins of the trigger mechanisms can be explored with electroanatomical mapping technique. Once identified, the trigger mechanism may be abolished by using the catheter ablation technique to cure the arrhythmia. We present the results for two patients with trigger mechanisms of different origin whose arrhythmia has been cured using the focal ablation technique.

To evaluate the feasibility of monophasic action potential (MAP) mapping using a modified-tip NaviStar catheter in swine and humans.MAP mapping was performed using the modified-tip catheter at 71 +/- 21 atrial and 60 +/- 16 ventricular sites in 10 healthy pigs and at 56 ventricular sites in one patient, and using an ordinary Navi-Star catheter at 30 atrial sites in one patient and 50 +/- 14 ventricular sites in four patients. In an additional 20 patients, MAPs were also recorded at 9 +/- 2 atrial sites using the modified-tip catheter or at 12 +/- 9 atrial sites using the ordinary catheter.In pigs, the plateau amplitudes of the MAPs recorded using the modified-tip catheter were 4.1 +/- 3.2 mV for the atrial and 9.5 +/- 4.3 mV for the ventricular MAPs. In patients, both the ventricular and atrial MAPs recorded using the modified-tip catheter were significantly higher than using the ordinary catheters, 15.7 +/- 8 and 3.0 +/- 0.9 mV vs 9.5 +/- 3.9 and 2.0 +/- 0.6 mV for the ventricular and atrial MAPs, respectively (p0.0001). The baseline disturbances were10% of the MAP amplitude in 95% of the pig and 96% of the patient MAPs.A modified-tip Navi-Star catheter could be used in swine and in humans for prompt recording of MAPs with acceptable amplitudes and baselines. MAP mapping using the modified-tip catheter is safe and feasible for clinical use.

This article evaluates whether the global dispersion of ventricular repolarization (DVR) can be estimated from measurements between a few adjacent or remote sites. Monophasic action potentials (MAP) were recorded from 61 +/- 18 left (LV) or right ventricular (RV) sites in 10 pigs and 44 +/- 16 LV, or RV sites in 8 patients by using the CARTO mapping system. MAP duration (MAPd) and end-of-repolarization time were calculated at each site and 13 repolarization maps from pigs and 10 from patients were reconstructed. Global dispersions in MAPd and EOR over the LV or RV were compared with the adjacent DVR among 3 - 7 MAPs in areas > or = 0.7 and < or = 1 cm(2) and with the remote DVRs between 2 MAPs with the greatest activation time difference (remote DVR1) and between the apical and laterobasal LV or RV (remote DVR2). The adjacent dispersions in end-of-repolarization and MAPd were significantly smaller than the global ones, 13 +/- 3 and 12 +/- 3 ms vs. 44 +/- 9 and 42 +/- 12 ms in pigs and 13 +/- 7 and 14 +/- 8 ms vs. 72 +/- 24 and 66 +/- 22 ms in patients. The remote DVR1 (30 +/- 8 and 17 +/- 10 ms in pigs and 40 +/- 28 and 28 +/- 17 ms in patients) and remote DVR2 (16 +/- 7 and 11 +/- 10 ms in pigs and 35 +/- 24 and 21 +/- 21 ms in patients) were also significantly smaller than the global DVRs. In conclusion, global DVR is poorly estimated from MAP recordings from a few adjacent or remote sites, suggesting the importance of obtaining global information in evaluating DVR.

BACKGROUND: Recent reports suggest the presence of conduction delay in the posterior septal region during sinus rhythm in patients with lone paroxysmal atrial fibrillation (AF). OBJECTIVE: To explore the location of intra-atrial conduction delay associated with initiation of AF. DESIGN: In 8 lone AF patients (51 +/- 10 years), 20 AF paroxysms were induced during electrophysiological examination. Bipolar electrograms were acquired from a 10-polar catheter in the coronary sinus (CS), a 4-polar His bundle catheter, and a 20-polar Halo catheter in the right atrium. RESULTS: Induced AF paroxysms showed earliest registered atrial activity in interatrial septum (IAS) or proximal CS in 17 cases (85%). Conduction delay at the posterior IAS or proximal CS accompanied induction of 18 AF paroxysms (6 patients). Atrial activation sequence at the beginning of the AF paroxysms was stable and reproducible in six repeatedly induced AF episodes (3 patients). CONCLUSION: In lone AF patients, induction of AF is associated with conduction disturbances in the IAS and proximal CS regions.

The aim of this study was to evaluate the global sequence of repolarization over the ventricular endocardium. Disturbances in myocardial repolarization are associated with the genesis of arrhythmias. However, little is known about the global sequence of repolarization. Monophasic action potentials (MAPs) were recorded from 61 +/- 18 LV and/or RV sites in ten healthy pigs and from 43 +/- 15 LV or RV sites in eight patients using the CARTO system. Local activation time (AT), end-of-repolarization (EOR) time, and MAP duration were calculated and three-dimensional global maps of AT, EOR, and MAP duration constructed. LV maps were obtained from all ten pigs and RV maps from three pigs. Five RV maps and five LV maps were obtained from the eight patients. (1) EOR sequence was recognizable in 12 of 13 pig maps and in all the patient maps. (2) EOR followed the sequence of activation in 12 of 13 pig maps and 8 of 10 patient maps. (3) The longest MAPs were recorded in or near the earliest activation area, and the shortest ones in or near the latest activation area in all the pig maps and in nine of ten and eight of ten patient maps, respectively. (4) In all maps, MAP duration and AT were negatively correlated, and EOR and AT positively correlated. In conclusion, repolarization gradients exist over the pig and the human ventricular endocardium. The activation sequence is a determinant for the repolarization sequence. The magnitude of the progressive MAP shortening with progressively later activation, relative to local AT, is a critical factor governing the direction and pattern of the EOR. (Less)

The objective of this study was to delineate the sex distribution and atrioventricular conduction properties in patients with manifest or concealed Wolff-Parkinson-White syndrome (WPW) and atrioventricular nodal reentrant tachycardia (AVNRT). The study comprised 328 patients with AVNRT, 347 with manifest, and 220 with concealed WPW who underwent radiofrequency ablation. A male preponderance was observed in patients with manifest WPW (69%), but not in those with concealed WPW (52%) and female preponderance in AVNRT patients (67%). The PR (166 +/- 25 ms) and AH (88 +/- 20 ms) intervals obtained 30 minutes after ablation in manifest WPW patients were significantly longer than in concealed WPW patients (149 +/- 20, 76 +/- 15 ms, P

AIMS: Prolongation of interatrial conduction time has been reported in patients with paroxysmal atrial fibrillation (PAF). The study objective was to localize the region of the conduction delay in patients with lone PAF. METHODS AND RESULTS: Twenty-one patients with lone PAF and 23 patients with AV nodal re-entrant tachycardia ablation without history of PAF (control group) were recruited. Endocardial recordings were made during sinus rhythm and programmed atrial stimulation. The authors measured the interatrial conduction time, the 'right-sided' conduction time between the high lateral right atrium and the proximal coronary sinus (RA-CSp), and the 'left-sided' conduction time between the proximal and the distal coronary sinus (CSp-LA). During sinus rhythm, the interatrial conduction time was longer in the PAF group (103 +/- 19 vs 86 +/- 12 ms, P

AIMS: The monophasic action potential (MAP) is conventionally recorded using Ag-AgCl electrodes which are not suitable for delivering radiofrequency currents. To be able to use the sharp MAP upstroke for identifying the local activation, as a step towards the development of a MAP-guided catheter ablation technique, the possibility of recording MAP via platinum electrodes of an ordinary ablation catheter was explored. METHODS AND RESULTS: One hundred and forty-two MAP recordings from the endocardium were obtained via an ablation catheter in 40 patients undergoing electrophysiological study/catheter ablation. During sinus rhythm and pacing, 90% of the ventricular and 100% of the atrial MAPs had stable baselines. The amplitudes were 13 +/- 4.2 mV for ventricular and 2.4 +/- 0.8 mV for atrial MAPs. During mapping and ablation, MAPs and uni- and bipolar electrograms were recorded simultaneously using the same tip electrode in eight patients. The MAPs provided more distinct local activation than the electrograms. During 17 MAP recordings, additional MAPs were recorded simultaneously using an Ag-AgCl electrode catheter in the immediate vicinity of the ablation catheter. The MAPs taken with the ablation catheter had characteristics consistent with those taken with the Ag-AgCl catheter. CONCLUSIONS: (1) Platinum electrodes can be used for timely recording of MAPs in patients. (2) It is feasible to record MAPs and deliver radiofrequency currents via the same platinum-tip electrode. These findings suggest that MAP-guided catheter ablation is technically possible. (Less)