BACKGROUND: Radiofrequency catheter ablation was introduced the curative method of supraventricular tachycardia in patients with accessory pathways. The success of catheter ablation depends on the accurate localization of accessory pathway and the destruction of accessory pathways. METHOD: We analyzed the local electrograms in 35 patients to be underwent the successful catheter ablation and measured the catheter stability, A/V ratio, AV interval, Accessory pathway potential, and the interval from the onset of RF energy to loss of accessory pathway from local electrograms at the successful ablation sites. RESULTS: The ratio of A wave and V wave range from 0.06 to 6.33 and the mean of A/V ratio is 0.62. The shortest AoVo interval is 20 msec and the longest AoVo interval is 120 msec and the mean of AoVo interval is 58.23 msec. The shortest ApVp interval is 20 msec and the longest ApVp interval is 100 msec and the mean of this interval is 51.88 msec. The incidence of accessory pathway potential among 35 successful ablation sites in 25%. The mean of time from RF energy to loss of accessory pathway is 4.48 sec. CONCLUSION: We concluded that the finding of local electrogram during catheter ablation is very important for shortening of procedure time and the successful procedure.
Catheter Ablation* ; Catheters ; Electrophysiologic Techniques, Cardiac* ; Humans ; Incidence ; Tachycardia, Supraventricular

Pacemaker twiddler's syndrome is reported as a very rare complication of permanent pacemaker implantation. There was a recent report suggesting that the incidence of pacemaker twiddler's syndrome increase recently presumably as a result of the implantation of thinner and smaller pacemaker system than before. We experienced a case of pacemaker twiddler's syndrome complicated 3 times with the conventional method of implantation or replacement during 14 months after the first implantation(Optims MP 158C and Pacing lead 400, Telectronic)on June 13th 1987. This case was an 18 year-old high school girl who had suffered frequent syncope for 2 years and extertionl dyspnea for 5 years due to congenital complete heart block, of which block site was proved to be AV nodal by His bundle electrogram. Pacemaker twiddler's syndrome developed 3 times;firstly 6 weeks after the first implantation in the right subclavicular fossa, secondly 10 weeks after the replacement of the twisted pacing lead, thirdly 10 months after the change of implantation site to the left subcalvicular fossa with the replacement of the twisted and fractured lead. Finally, the pacemaker generator was anchored to the clavicular periostium and pectoralis fascia at several points by using Dacron pouch.
Adolescent ; Dyspnea ; Electrophysiologic Techniques, Cardiac ; Fascia ; Female ; Heart Block ; Humans ; Incidence ; Polyethylene Terephthalates ; Syncope

BACKGROUND AND OBJECTIVES: Ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia (AVNRT) can be performed by using a specific intracardiac electrogram findings predicting a successful radiofrequency catheter ablation. The purpose of the present study is to recognize a specific intracardiac electrogram findings predicting a successful sites of radiofrequency catheter ablation in patients with AVNRT. MATERIALS AND METHODS: The study population consisted of the 18 patients (7 males, mean age:46 yr) to undergo successful catheter ablation using radiofrequency current in order to eliminate AVNRT from January 1993 to september 1994. We have analyzed local intracardiac electrogram at successful and unsuccessful sites of radiofrequency catheter ablation before the radiofrequency application: Atrial electrogram amplitude, duration, number of peaks in atrial electrogram, atrial/ventricular (A/V) electrogram amplitude ratio, and presence of His potential and/or slow potential. RESULTS: Of 18 patients, 16 patients underwent a slow pathway ablation, the other 2 patients a fast pathway ablation. The mean A/V electrogram amplitude ratio at successful and unsuccessful sites was 0.69+/-0.91 and 1.86+/-2.03, respectively. The mean atrial electrogram duration and number of peaks at successful and unsuccessful sites was 57+/-16 msec vs 69+/-16 msec and 1.7+/-0.5 vs 2.2+/-0.7, respectively. His bundle electrogram was seen in one slow pathway ablated and one fast pathway ablated patient. No slow potential could be identified in any of these 18 patients. CONCLUSION: We think that A/V electrocardiogram amplitude ratio below 0.5 at posterior interatrial septum along tricuspid annulus is important marker indicating a successful ablation sites.
Catheter Ablation* ; Electrocardiography ; Electrophysiologic Techniques, Cardiac* ; Humans ; Male ; Tachycardia, Atrioventricular Nodal Reentry*

His bundle recordings enable us to diagnose conduction disturbances not discernable in the standard leads, and to localize conduction block in the subdivisions of the conduction system. Cases of intra-His bundle block were first reported in 1970 by Narula and Samet. Thereafter many additional reports and studies were made. We report a case of 3degrees A-V block due to conduction block at the His bundle level. A 71-year-old woman was admitted because of dizziness. Surface ECG showed 3degrees A-V block. His bundle electrogram revealed typical split His potential. A-H intervals were 80 msec and H'-V intervals 50~70 msec. And there found no relation between AH and H'A. Atrial pacing resulted only prolongation of A-H to 90 msec but dissociation between h and H' was consistent. We implanted a permanent endocardial pacemaker in her chest.
Aged ; Bundle of His ; Dizziness ; Electrocardiography ; Electrophysiologic Techniques, Cardiac ; Female ; Humans ; Thorax

Clinical EPS was performed in 16 normal adults without evidence of conduction disease on the surface standard 12 lead electrocardiogram in order to provide normal electrophysiological values of the sinus node function and AV conduction. EPS was also performed in 15 patients with sick sinus syndrome and 10 patients with AV conduction disturbance to evaluate the clinical usefulness of EPS in detecting sinus node dysfunction and AV conduction disturbance. The results were as follows. 1) The results of sinus node function test in the normal group were m-SNRT 853+/-198msec(range 800-1,560msec), c-SNRT 230+/-66msec(range 120-370msec), and %m -SNRT/SCL 127+/-11%(range 114-149%). 2) In 15 patients with SSS, the M-SNRT were ranged from 1,270 to 12,330msec and 10 patients(66%) had significantly increased m-SNRT exceeding 1,560msec. The c-SNRT were ranged from 230 to 10,730msec and 13 patients(83%) had significantly increased c-SNRT exceeding 370msec. The % m-SNRT/SCL were ranged from 136 to 770% and 12 patients(80%) had significantly increased % m-SNRT/SCL exceeding 150%. 3) The SACT in normal group were 84+/-14msec(range 70-105msec) measured by continuous atrial pacing method and 80+/-19 msec(range 60-115msec) measured by atrial extrastimulation method. 4) In SSS, the SACT measured by continuous atrial pacing method was ranged from 80 to 1,050msec and 11/12 patients(92%) had significantly increased SACT exceeding 112 msec. The SACT measured by atrial extrastimulation method was ranged from 90 to 310msec and 7/8 patients(88%) had significantly increased SACT exceeding 118 msec. 5) C-SNRT, % m-SNRT/SCL, and SACT were more useful in detecting sinus node dysfunction than m-SNRT. 6) The AV conduction intervals in normal group were PA interval 17+/-6(range 5-25msec), AH interval 96+/-18 msec(range 70-135msec), and HV interval 46+/-7msec(range 35-55msec). 7) Rapid atrial pacing induced Wenckebach type second degree AV block proximal to H at pacing rate of 90 to 190/min in 14/16 normal adults. 2 patients maintained intact AV conduction upto maximum pacing rate of 200/min. 8) His bundle electrogram showed the site of AV block in 9 of 10 patients with AV conduction disturbances. The sites of AV block were AV nodal area 1 case, intraHis bundle 4 cases, and infraHis bundle 4 cases. 9) EPS provided a good supportive information that was useful in selecting pacemaker therapy in a patient with chronic bifascicular block who revealed prolonged HV interval and infraHis bundle block at a pacing rate of 70min. 10) The refractory periods of AV conduction system in normal group were AERP 274+/-54msec (range 170-410msec), AVN-FRp 467+/-74msec(range 285-600msec), AVN-ERP 341+76msec(range 190-460), and V-ERP 280+/-25msec(range 240-320msec).
Adult ; Atrioventricular Block ; Electrocardiography ; Electrophysiologic Techniques, Cardiac ; Humans ; Sick Sinus Syndrome ; Sinoatrial Node*

BACKGROUNDAblation of complex fractionated atrial electrograms (CFAE) is an important adjunctive therapy in atrial fibrillation (AF). The present study was to elucidate the substrate underlying CFAE.

METHODSNine adult mongrel dogs were involved in the present study. AF was induced through rapid atrial pacing with vagosympathetic nerve stimulation. CFAE was recorded during AF. Ablation was performed at CFAE sites. Based on the location of the ablation scar, the atrial specimens were divided into CFAE and non-CFAE sites. Serial sections of the atrium were stained respectively with hematoxylin-eosin (HE) and the general neural marker protein gene product 9.5 (PGP9.5). We compared the characteristics of the myocardium and the ganglionated plexus (GPs) distribution between the CFAE and non-CFAE sites.

RESULTSThe myocardium of non-CFAE sites was well-organized with little intercellular substance. However, the myocardium in the CFAE site was disorganized with more interstitial tissue ((61.7 ± 24.3)% vs. (34.1 ± 9.2)%, P < 0.01). GPs in the CFAE site were more abundant than in non-CFAE sites ((34.45 ± 37.46) bundles/cm(2) vs. (6.73 ± 8.22) bundles/cm(2), P < 0.01).

CONCLUSIONThe heterogeneity of the myocardium and GPs distribution may account for the substrate of CFAE and serve as a potential target of ablation.

Catheter ablation of the AV nodal slow pathway using radiofrequency (RF) energy has been established as the first-line curative therapeutic modality of recurrent symptomatic AV nodal reentrant tachycardia (AVNRT). In contrast to catheter ablation of the AV bypass tract, there was no useful marker to localize succesful site of the pathway. This study was performed to determine predictors of successful catheter ablation of the AV nodal slow pathway in patients with AVNRT. METHODS: Forty patients (18 men, 22 women; 47.9+/-13.3 years) with AVNRT undergoing successful catheter ablation of the AV nodal slow pathway were included in this study, in which 217 attempts were tried to ablate the AV nodal slow pathway. Characteristics of local atrial electrogram, anatomical site at each attempt, junctional rhythm during RF delivery were analyzed (40 successful, 177 failed). Maximum difference and duration of atrial electrograms were measured and local atrial electrograms were classified into 5 types (A1, A2, B1, B2 and C type) according to the type and the degree of fragmentation. Finally, the occurrence of junctional rhythm during RF discharge and its onset time were compared between successful and failed attempts. RESULTS: There was no significant difference in the maximum difference of amplitude and duration of atrial electrograms between successful and failed attempts. The success rate in each type of atrial electrogram was significantly different. And, the success rate in non-C type atrial electrograms (A1, A2, B1, and B2) was significantly higher than that in type C atrial electrograms (25.0% vs 10.3%, p<0.01). No significant difference was noted in success rates according to attempted sites. Junctional rhythms during radiofrequency application occured significantly more frequent in successful attempts than in failed attempts (87.5% vs 47.5%, p<0.001). The time to onset of junctional rhythm was not different between successful and failed attempts (5.2+/-4.9 sec vs 6.1+/-5.5 sec). CONCLUSION: Fragmented local atrial electrogram and junctional rhythm during RF energy delivery may be used to predict successful catheter ablation of AVNRT. It is recommended that RF energy should be applied to the site where fragmented atrial electrogram is recorded and terminated if junctional rhythm does not develop within 15 seconds after starting RF energy delivery.
Catheter Ablation* ; Catheters* ; Electrophysiologic Techniques, Cardiac ; Female ; Humans ; Male ; Tachycardia, Atrioventricular Nodal Reentry*

Catheter ablation of the AV nodal slow pathway using radiofrequency (RF) energy has been established as the first-line curative therapeutic modality of recurrent symptomatic AV nodal reentrant tachycardia (AVNRT). In contrast to catheter ablation of the AV bypass tract, there was no useful marker to localize succesful site of the pathway. This study was performed to determine predictors of successful catheter ablation of the AV nodal slow pathway in patients with AVNRT. METHODS: Forty patients (18 men, 22 women; 47.9+/-13.3 years) with AVNRT undergoing successful catheter ablation of the AV nodal slow pathway were included in this study, in which 217 attempts were tried to ablate the AV nodal slow pathway. Characteristics of local atrial electrogram, anatomical site at each attempt, junctional rhythm during RF delivery were analyzed (40 successful, 177 failed). Maximum difference and duration of atrial electrograms were measured and local atrial electrograms were classified into 5 types (A1, A2, B1, B2 and C type) according to the type and the degree of fragmentation. Finally, the occurrence of junctional rhythm during RF discharge and its onset time were compared between successful and failed attempts. RESULTS: There was no significant difference in the maximum difference of amplitude and duration of atrial electrograms between successful and failed attempts. The success rate in each type of atrial electrogram was significantly different. And, the success rate in non-C type atrial electrograms (A1, A2, B1, and B2) was significantly higher than that in type C atrial electrograms (25.0% vs 10.3%, p<0.01). No significant difference was noted in success rates according to attempted sites. Junctional rhythms during radiofrequency application occured significantly more frequent in successful attempts than in failed attempts (87.5% vs 47.5%, p<0.001). The time to onset of junctional rhythm was not different between successful and failed attempts (5.2+/-4.9 sec vs 6.1+/-5.5 sec). CONCLUSION: Fragmented local atrial electrogram and junctional rhythm during RF energy delivery may be used to predict successful catheter ablation of AVNRT. It is recommended that RF energy should be applied to the site where fragmented atrial electrogram is recorded and terminated if junctional rhythm does not develop within 15 seconds after starting RF energy delivery.
Catheter Ablation* ; Catheters* ; Electrophysiologic Techniques, Cardiac ; Female ; Humans ; Male ; Tachycardia, Atrioventricular Nodal Reentry*

We report the case of a 64-year-old male with persistent atrial fibrillation (AF) terminated by ethanol infusion into vein of Marshall as add-on therapy. Three-dimensional automated complex fractionated atrial electrogram (CFAE) during AF revealed clustering of CFAE at perimitral isthmus (PMI) and its unipolar mapping showed rotor-like activation, which was suggested to be critical in the perpetuation of AF. AF was organized to atrial tachycardia (AT) by 100% ethanol infusion in the vein of Marshall. Adjunctive radiofrequency ablation at PMI successfully terminated AT and led to bidirectional block of PMI.
Atrial Fibrillation* ; Catheter Ablation ; Electrophysiologic Techniques, Cardiac ; Ethanol* ; Humans ; Male ; Middle Aged ; Tachycardia ; Veins*

BACKGROUND AND OBJECTIVES: Although ablation of complex fractionated atrial electrograms (CFAE) in atrial fibrillation (AF) is one of the strategies for atrial substrate modification, the mechanism behind CFAE as an electrophysiological substrate remains unclear. We investigated structural differences between CFAE sites and their matched non-CFAE sites by comparing their histopathologic characteristics in canine AF models. METHODS: Atrial electrograms of four dogs were obtained from the epicardial site. AF was induced through burst atrial pacing at 600 bpm for 30 min. CFAE sites were identified during AF according to patterns visualized on the electrograms, and their matched non-CFAE sites were selected in the adjacent region, within 5 mm of each CFAE site. Tissues were harvested from CFAE sites and their matched non-CFAE sites at various locations in both atria. Histopathologic differences were identified between CFAE and non-CFAE sites. RESULTS: A total of 24 atrial tissues (12 with CFAE, 12 with non-CFAE) were evaluated. The atrial myocardium was significantly thicker at CFAE sites (1757.5±560.5 µm) than at non-CFAE sites (1279.5±337.2 µm) (p=0.036). At CFAE sites, it was filled with a significantly larger amount of fibrotic tissue than at non-CFAE sites (22.8±6.9% versus 7.2±4.7%, p < 0.001). Results were consistent across various tissue locations. The distribution of autonomic nerve innervation was similar between CFAE and non-CFAE sites. CONCLUSION: This study provides a better understanding of histological characteristics of CFAE sites, namely a thicker wall and greater amount of fibrosis. These findings may be associated with the development of CFAE and its pathophysiological contribution to AF.
Animals ; Atrial Fibrillation ; Autonomic Pathways ; Catheter Ablation ; Dogs ; Electrophysiologic Techniques, Cardiac ; Fibrosis ; Myocardium