Case Report: Clinical AV Nodal Reentrant Tachycardia in a Patient with Left Sided Accessory Pathway and Immediate Occurrence of Antidromic AV Reentrant Tachycardia after Slow Pathway Ablation

The only inducible arrhythmia in a patient with exclusive antegrade conducting left anterolateral accessory pathway, consists of slow/fast atrioventricular nodal reentrant tachycardia. After radiofrequency catheter ablation of the slow pathway, true antidromic AV reentrant tachycardia was easily induced by atrial pacing. Following ablation of the accessory pathway no arrhythmia could be induced.     

Slowing of the Ventricular Rate During Atrial Fibrillation by Ablation of the Slow Pathway of AV Nodal Reentrant Tachycardia

Influence of Slow Pathway Ablation on Atrial Fibrillation. Introduction : The mechanisms whereby radiofrequency catheter modification of AV nodal conduction slows the ventricular response are not well defined. Whether a successful modification procedure can be achieved by ablating posterior inputs to the AV node or by partial ablation of the compact AV node is unclear. We hypothesized that ablation of the well-defined slow pathway in patients with AV nodal reentrant tachycardia would slow the ventricular response during atrial fibrillation.
Methods and Results : In 34 patients with dual AV physiology and inducible AV nodal reentrant tachycardia, atrial fibrillation was induced at baseline and immediately after successful slow pathway ablation and at 1-week follow-up. The minimal, maximal, and mean RR intervals during atrial fibrillation increased from 353 ± 76,500 ± 121, and 405 ± 91 msec to 429 ± 84 (P < 0.01), 673 ± 161 (P < 0.01), and 535 ± 98 msec (P < 0.01), respectively. These effects remained stable during follow-up at 1 week. The AV block cycle length increased from 343 ± 68 msec to 375 ± 60 msec (P < 0.05) immediately and to 400 ± 56 msec (P < 0.01) at 1-week follow-up. The effective refractory period of the AV node prolonged from 282 ± 83 msec to 312 ± 89 msec and to 318 ± 81 msec after 1 week (P < 0.05), respectively.
Conclusion : This study shows a decrease in ventricular response to pacing-induced atrial fibrillation after ablation of the slow pathway in patients with AV nodal reentrant tachycardia. Since the AV nodal conduction properties could be defined, this study supports the hypothesis that the main mechanism of AV nodal modification in chronic atrial fibrillation is caused by ablation of posterior inputs to the AV node.     

Pathological Findings Following Slow Pathway Ablation for AV Nodal Reentrant Tachycardia

Pathology of Slow Pathway Ablation. Introduction : AV nodal reentrant tachycardia is routinely cured using radiofrequency catheter ablation techniques. However, there remains controversy as to whether the reentrant circuit for this tachycardia exists solely in the AV node or whether perinodal atrial tissues are vital to the circuit. In addition, the effects of radiofrequency ablation of the slow pathway of AV nodal reentrant tachycardia on the AV node are not known. We examined an autopsy specimen to determine the anatomical location and extent of AV nodal damage of radiofrequency slow pathway ablation for cure of AV nodal reentrant tachycardia.
Methods and Results : A 64-year-old woman with confirmed AV nodal reentrant tachycardia underwent a successful "slow pathway" AV modification with a single radiofrequency application. Five months after the procedure, the patient died from a spontaneous intracranial hemorrhage. Postmortem gross pathological examination of the heart was performed. The heart was then sectioned and stained for histologic examination. On gross examination, a pale lesion 0.5 cm in diameter was seen on the endocardial surface adjacent to the tricuspid annulus. approximately 0.85 cm anterior to the coronary sinus os and 1.15 cm from the apex of the triangle of Koch where the AV node resides. Histologic examination revealed a right atrial lesion composed of connective tissue and fat. The compact AV node and surrounding transitional cells were unaffected histologically, with normal atrial cells lying between the AV node and the lesion.
Conclusion : Ablation of the slow pathway to cure AV nodal reentrant tachycardia does not produce any gross or histologic damage to the AV node, suggesting that the AV nodal reentrant circuit does not exist in its entirety in the AV node.     

Optimal Target Site for Slow AV Nodal Pathway Ablation

INTRODUCTION: Although a variety of ablation techniques have been developed in the treatment of atrioventricular nodal reentrant tachycardia (AVNRT), there have been few reports discussing the location of the optimal target site. Based on our early experiences, we hypothesized that radiofrequency (RF) current applied around the upper margin of the coronary sinus ostium (UCSO) results in the most effective and safe treatment of AVNRT. METHODS AND RESULTS: To confirm our hypothesis, the efficacy of RF currents applied around the UCSO guided by local electrograms in 59 patients (group B: predetermined focal mapping approach) were compared with the outcomes in 60 other patients previously treated with the standard electrogram-guided mapping method starting around the lower margin of the coronary sinus ostium (group A). The precise location of ablation catheters at successful sites (S) was also evaluated. All the patients were successfully treated without complications. Significantly fewer RF pulses and lower energies were needed in group B patients (mean RF applications: 4.3 vs 1.4 applications, mean total energy delivered: 4,699 vs 2,236 J in groups A and B, respectively, P < 0.01). Detailed analyses of the anatomical locations of S using CS venography in group B patients who received only a single RF application (46 patients) revealed that the distance between His and S varied according to the length of Koch's triangle, while that between S and UCSO was relatively constant. In 85 % of these 46 patients, S was located within 5 mm above and below the level of the UCSO. CONCLUSION: RF applications around the UCSO guided by local electrograms yielded excellent outcomes in AVNRT patients with wide varieties in the size of Koch's triangle. The optimal target site was located within 5 mm above and below the level of UCSO along the tricuspid annulus.     

The Electrophysiologic Characteristics in Patients with Only Ventricular-Pacing Inducible Slow–Fast Form Atrioventricular Nodal Reentrant Tachycardia

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) can be usually induced by atrial pacing or extrastimulation. However, it is less commonly induced only by ventricular pacing or extrastimulation. Objective: The purpose of this retrospective study was to investigate the electrophysiologic characteristics in patients with slow–fast form AVNRT that could be induced only by ventricular pacing or extrastimulation. Methods: The total population was 1497 patients associated with AVNRT. There were 1373 (91.7%) patients who had slow–fast form AVNRT included in our study. Group 1 (n = 45) could be induced only by ventricular pacing or extrastimulation, and Group 2 (n = 1328) could be induced by only atrial stimulation or both atrial and ventricular stimulation. The electrophysiologic characteristics of the group 1 and group 2 patients were compared. Results: Group 1 patients had a significantly lower incidence of both antegrade and retrograde dual AV nodal pathways. The pacing cycle length (CL) of the antegrade 1:1 fast pathway (FP) and antegrade ERP of the FP were both significantly shorter in Group 1 patients. Mean antegrade FRP of the fast and slow pathways were significantly shorter in Group 1 patients. The differences of pacing CL of 1:1 antegrade conduction, antegrade ERP and FRP were much longer in Group 2 patients. Conclusion: This study demonstrated the patients with slow–fast form AVNRT that could be induced only by ventricular stimulation had a lower incidence of dual AV nodal pathways and the different electrophysiologic characteristics (shorter pacing CL of the antegrade 1:1 FP, antegrade ERP of the FP and the differences of pacing CL of 1:1 antegrade conduction, antegrade ERP and FRP) from the other patients. The specific electrophysiologic characteristics in such patients could be the reason that could be induced only by ventricular stimulation.     

Single Radiofrequency Application to Cure Atrioventricular Nodal Reentry: Arguments for the Slow Pathway Origin of the High-Low Frequency Slow Potentials

Background: High-low frequency slow potentials are thought to be related to the slow AV pathway conduction. Their use was proposed to guide radiofrequency (RF) ablation of atrioventricular nodal reentrant tachycardia (AVNRT). The present study was designed to determine the prospective value of these high-low frequency slow potentials to guide AVNRT ablation using a single RF application. Single RF application could indeed reduce the size of the lesion created in the viciny of the specialized AV conduction system and shorten the radiation exposure and the overall duration of the procedure.Results: Forty-one patients (14 men, 27 women, 45&plusmn;16 years old) with AVNRT underwent slow pathway RF ablation guided by high-low frequency slow potentials. High-low frequency slow potentials were found in all patients along the tricuspid annulus and above the coronary sinus. Ablation was always performed in the posterior part of Koch's triangle. The mean A/V amplitude ratio of the successful site was 0.43&plusmn;0.59. In 32 patients (78%) AVNRT was no longer inducible after a single RF application. Procedure and radiation times were 35&plusmn;31 and 13&plusmn;12 min respectively. Five patients required 2, 3 patients 3, and 1 patient 6 RF applications. The mean number of RF applications was 1.4&plusmn;0.9 (median &equals; 1). In the 32 patients who required only one RF application, 24 (75%) had an obvious dual AV nodal pathways with a jump before ablation, wich completely disappeared in 18 of them (75%) after ablation. In the 6 remaining patients, who still had a jump after 1 RF application, there was no significant change in either conduction times or refractory periods concerning both the anterograde and retrograde AV conduction. No patient had PR interval purlongation. After a mean follow up of 11&plusmn;5 months, recurrence was observed in a single patient who received 2 discontinued RF applications.Conclusion: Catheter-mediated ablation of AVNRT using high-low frequency slow potentials to localize the slow AV pathway is feasible and safe. Using this technique, a single RF application was successfull in 78% of patients, and slow pathway characteristics were completely eliminated in 75% of patients. The radiation time and the procedure duration were short. This suggest that, in patients with AVNRT, the choice of an appropriate RF target can reduce procedural duration.     

Target Temperatures of 48°C versus 60°C During Slow Pathway Ablation:

INTRODUCTION: The relationship between temperature at the electrode-tissue interface and the loss of AV and ventriculoatrial (VA) conduction is not established, and the optimal target temperature for the slow pathway approach to radiofrequency ablation of AV nodal reentrant tachycardia (AVNRT) is unknown. Therefore, the purpose of this study was to compare target temperatures of 48 degrees C and 60 degrees C during the slow pathway approach to ablation of AVNRT. METHODS AND RESULTS: The study included 138 patients undergoing ablation for AVNRT. Patients undergoing slow pathway ablation using closed-loop temperature monitoring were randomly assigned to a target temperature of either 48 degrees C or 60 degrees C. The primary success rates were 76% in the patients assigned to 48 degrees C and 100% in the patients assigned to 60 degrees C (P < 0.01). The ablation procedure duration (33 +/- 31 min vs 26 +/- 28 min; P = 0.2), fluoroscopic time (25 +/- 15 min vs 24 +/- 16 min; P = 0.5), and mean number of applications (9.3 +/- 6.5 vs 7.8 +/- 8.1; P = 0.3) were similar in patients assigned to 48 degrees and 60 degrees C, respectively. The mean temperature (46.1 degrees +/- 24.8 degrees C vs 48.7 +/- 3.2 degrees C; P < 0.01), the temperature associated with junctional ectopy (48.1 degrees +/- 2.0 degrees C vs 53.5 degrees +/- 3.5 degrees C, P < 0.0001), and the frequency of VA block during junctional ectopy (24.6% vs 37.2%; P < 0.0001) were less in the patients assigned to 48 degrees C compared to 60 degrees C. The frequency of transient or permanent AV block was similar in each group (2.8% vs 3.6%; P = 0.2). In the 60 degrees C group, only 12% of applications achieved an electrode temperature of 60 degrees C. During follow-up of 9.9 +/- 4.2 months, there was one recurrence of AVNRT in the 48 degrees C group and none in the 60 degrees C group. CONCLUSIONS: Compared to 48 degrees C, a target temperature of 60 degrees C during radiofrequency slow pathway ablation is associated with a higher primary success rate and a higher incidence of VA block during junctional ectopy induced by the radiofrequency energy. AV block is not more common with the higher target temperature, but only if VA conduction is aggressively monitored during applications of radiofrequency energy.     

Location of the lower turnaround point in typical AV nodal reentrant tachycardia: a quantitative model

INTRODUCTION: Recent observations suggest that the circuit of AV nodal reentrant tachycardia (AVNRT) may extend down to the His bundle. The purpose of this study was to develop a quantitative model indicating the location of the lower turnaround point in AVNRT. METHODS AND RESULTS: Slow pathway modification was performed in 70 patients with typical AVNRT. During sinus rhythm, ventricular pacing was performed with the AVNRT cycle length. During AVNRT, the HinitAinit interval was measured from initial His to the initial atrial deflection recorded in the His-bundle lead. During ventricular pacing, the HendAinit interval was measured from end of the His to the beginning of the atrial deflection. It was hypothesized that x reflects conduction time from the lower turnaround point to Ainit, whereas y reflects conduction time from the lower turnaround point to Hinit. Anterograde conduction during AVNRT and retrograde conduction during ventricular pacing were assumed to be identical if there was 1:1 retrograde conduction at the AVNRT cycle length. The following formulas describe the relation of the measured parameters: x - y = HinitAinit; and x + y = HendAinit. Resolving both formulas yields the unknown x and y: y = (HendAinit - HinitAinit)/2, x = (HendAinit + HinitAinit)/2. These criteria were present in 52 of 70 patients. The mean cycle length of AVNRT was 355 +/- 42 msec, mean HinitAinit was 54 +/- 27 msec, and mean HendAinit was 60 +/- 29 msec. Accordingly, in 20 of 52 patients, the lower turnaround point was located within the His bundle (y = -15.4 +/- 16.1 msec), in 3 of 52 it was in the nodal-His junctional area (y = 0), and in 29 of 52 it was above the His bundle (y = +12.7 +/- 10.3 msec). The HinitAinit interval was significantly longer (66 +/- 32 msec vs 47 +/- 20 msec; P = 0.02) and the HendAinit interval was significantly shorter (45 +/- 30 msec vs 69 +/- 24 msec; P = 0.004) when the first group was compared with the others. CONCLUSION: In about 1 of 3 of patients with typical AVNRT, the lower turnaround point of the circuit is within the His bundle; in more than half of the patients it is above the His bundle. These data do not support the concept that all AVNRTs have an intranodal circuit, but are in accordance with the finding of longitudinal dissociation of the His bundle.     

Pseudo-Pacemaker Syndrome Following Inadvertent Fast Pathway Ablation for Atrioventricular Nodal Reentrant Tachycardia

Pseudo-Pacemaker Syndrome After AV Nodal Ablation. Atrioventricular nodal reentrant tachycardia that is refractory to drug treatment has recently been treated with radiofrequency catheter ablation. In this case report we describe a patient with atrioventricular nodal reentrant tachycardia in whom radiofrequency ablation of slow pathway was attempted, with inadvertent damage to the fast pathway. The patient developed marked first-degree atrioventricular block associated with symptoms mimicking pacemaker syndrome.     

Temperature and Impedance Monitoring During Slow Pathway Ablation in Patients with AV Nodal Reentrant Tachycardia

Slow Pathway Ablation. Introduction : Successful radiofrequency ablation of an accessory pathway has been demonstrated to be associated with an electrode-tissue interface temperature of approximately 60°C or an impedance change of −5 to −10 Ω. However, the temperature and impedance changes associated with ablation of AV nodal reentrant tachycardia (AVNRT) using the slow pathway approach have not been reported. Therefore, the purpose of this study was to define the temperature and impedance changes achieved during ablation of AVNRT.
Methods and Results : The study included 35 consecutive patients with AVNRT undergoing radiofrequency ablation of the slow pathway with a fixed power output of 32 W, and using a catheter with a thermistor bead embedded in the distal 4-mm electrode. The procedure was successful in each patient. The steady-state electrode-tissue interface temperature during successful applications of energy was 48.5 ± 3.3°C (range 42° to 56°C), and the steady-state temperature during ineffective applications was 46.8°± 5.5°C (P = 0.03). The mean impedance change during all applications of energy was −1.4 ± 2.8 ω, and did not differ significantly during effective and ineffective applications. Coagulum formation resulted during five applications (2.7%) in two patients (5.7%). There were no recurrences during 114 ± 21 days of follow-up.
Conclusions : Successful ablation of AVNRT using fixed power output is achieved at an electrode-tissue interface temperature of approximately 48°C and is associated with a drop in impedance of 1 to 2 ω. These findings suggest that slow pathway ablation requires less heating at the electrode-tissue interface than does accessory pathway or AV junction ablation.     

射频消融治疗房室结折返性心动过速不同终点的疗效观察

目的　评价射频消融治疗房室结折返性心动过速 ( AVNRT)的不同终点对远期复发的影响。方法　对 1 0 4例 AVNRT患者进行慢径消融 ,比较慢径传导消失组和慢径传导残留组 AVNRT复发率。结果　射频消融术后慢径传导消失 5 8例 ,慢径传导残留 4 6例 ,术后 1 8± 9个月随访期内 ,慢径传导消失组复发 2例 ( 3 .4 % ) ,慢径传导残留组复发 2例 ( 4.3 % ) ,两组无显著差别 ( P>0 .0 5 )。结论　射频消融术后慢径传导残留并不增加 AVNRT复发的危险性     

Radiofrequency Catheter Ablation of the Anterosuperior and Posteroinferior Atrial Approaches to the AV Node for Treatment of AV Nodal Reentrant Tachycardia

Catheter Ablation Techniques in AVNRT. Radiofrequency catheter ablation has been established as a first-line curative treatment modality in patients with symptomatic AV nodal reentrant tachycardia (AVNRT). The successful sites of stepwise catheter ablation approaches of the so-called fast and slow pathways strongly suggest that AVNRT involves the atrial approaches to the AV node. The typical fast pathway ablation sites are located anterosuperior toward the apex of the triangle of Koch, which also contains the compact AV node, whereas the usual slow pathway ablation sites are located posteroinferior toward the base of the triangle of Koch at a greater distance to the compact AV node and bundle of His. Accordingly, ablation studies with large patient cohorts have demonstrated that fast pathway ablation carries a higher risk of inadvertent complete AV block. Thus, the slow pathway is clearly the primary target site, and fast pathway ablation is rarely necessary. Different approaches for slow pathway ablation have been elaborated: anatomically oriented stepwise techniques, ablation guided by double potentials recorded within the area of the slow pathway insertion, and combined techniques. The modern concept of AVNRT suggests that this arrhythmia involves the highly complex three-dimensional nonuniform anisotropic AV junctional area. Accordingly, mapping and ablation studies demonstrated that the anterior approach is not identical with fast pathway ablation, and the posterior approach is not identical with slow pathway ablation. Therefore, it is essential for interventional electrophysiologists to familiarize themsdves with the anatomic and electrophysiologic details of this complex and variable specialized AV junctional region. In this review, the anatomic and pathophysiologic aspects of the AV junctional area as they relate to interventional therapy are summarized briefly, and the catheter techniques for ablation of the so-called fast and slow AV nodal pathways for the treatment of AVNRT are described.     

Electrophysiologic Characteristics and Radiofrequency Catheter Ablation in Atrioventricular Node Reentrant Tachycardia with Second-Degree Atrioventricular Block

Second-Degree AV Block During AVNRT. Introduction : Detailed electrophysiologic study of AV nodal reentrant tachycardia (AVNRT) with 2:1 AV block has been limited.
Methods and Results : Six hundred nine consecutive patients with AVNRT underwent electrophysiologic study and radiofrequency catheter ablation of the slow pathway. Twenty-six patients with 2:1 AV block during AVNRT were designated as group I, und those without this particular finding were designated as group II. The major findings of the present study were: (1) group I patients had better anterograde and retrograde AV nodal function, shorter tachycardia cycle length (during tachycardia with 1:1 conduction) (307 ± 30 vs 360 ± 58 msec, P < 0.001), and higher incidence of transient bundle branch block during tachycardia (18/26 vs 43/609, P < 0.001) than group II patients: (2) 21 (80.8%) group I patients had alternans of AA intervals during AVNRT with 2:1 AV block. Longer AH intervals (264 ± 26 vs 253 ± 27 msec, P = 0.031) were associated with the blocked beats. However, similar HA intervals (51 ± 12 vs 50 ± 12 msec, P = 0.363) and similar HV intervals (53 ± 11 vs 52 ± 12, P = 0.834) were found in the blocked and conducted beats; (3) ventricular extrastimulation before or during the His-bundle refractory period bundle could convert 2:1 AV block to 1:1 AV conduction.
Conclusions : Fast reentrant circuit, rather than underlying impaired conduction of the distal AV node or infranodal area, might account for second-degree AV block during AVNRT. Slow pathway ablation is safe and effective in patients who have AVNRT with 2:1 AV block.     

Case Report: Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in a Patient with Heart Transplantation

Ten years after orthotopic cardiac transplantation, a 56-year-old man developed recurrent presyncope and syncope. A 24-hour ambulatory electrocardiographic recording did not document significant arrhythmic events. A head-up tilt table test was negative. An electrophysiologic study revealed dual atrioventricular (AV) nodal physiology and inducible typical atrioventricular nodal reentrant tachycardia (AVNRT). The patient became hypotensive and presyncopal during AVNRT. Radiofrequency (RF) catheter ablation successfully eliminated AVNRT without complications. The patient remained free of symptoms at nine months follow-up.     

A Quantitative Fluoroscopic Comparison of the Coronary Sinus Ostium in Patients With and Without AV Nodal Reentrant Tachycardia

Coronary Sinus Ostium. Introduction : The purpose of this study was to perform a quantitative fluoroscopic analysis of the coronary sinus ostium and its relationship to the His bundle in patients with and without AV nodal reentrant tachycardia. Sites of slow pathway ablation are often near the coronary sinus ostium, which can be located within a few millimeters of the His bundle. Whether such close proximity of the coronary sinus ostium to the His bundle is unique to patients with AV nodal reentrant tachycardia is unknown.
Methods and Results : Fifty consecutive patients (mean age 39 ± 14 years) with no structural heart disease underwent electrophysiologic testing and radiofrequency ablation. The study group consisted of 28 patients with inducible AV nodal reentrant tachycardia or dual AV nodal physiology and 22 patients in the control group. A coronary sinus venogram was performed in each patient. The coronary sinus ostium was similar in size in the study group (11.4 ± 4.5 mm) and in the control group (10.5 ± 3.6 mm, P = 0.2). The coronary sinus ostium was funnel shaped in half of the study patients and in half of the control patients (P = 1.0). The mean distance from the upper lip of the coronary sinus ostium to the tip of the His bundle catheter was 9.7 ± 5.5 mm in the study group and 10.4 ± 5.1 mm in the control group (P = 0.7). The mean distance from the lower lip of the coronary sinus ostium to the tip of the His-bundle catheter in the study group was 20.1 ± 6.1 mm and 19.5 ± 5.6 mm in the control group (P =0.7).
Conclusion : This study demonstrates a wide range of normal coronary sinus ostium diameters, morphology, and anatomic relationships with surrounding structures, with no demonstrable correlation to the presence or absence of dual AV node physiology or AV nodal reentrant tachycardia.     

Persistence of Single Echo Beat Inducibility After Selective Ablation of the Slow Pathway in Patients with Atrioventricular Nodal Reentrant Tachycardia:

Residual Slow Pathway Conduction Effects on AVN Function. Introduction : Residual slow pathway conduction with or without reentrant echo beats has been reported in 25% to 30% of patients undergoing ablation for AV nodal reentrant tachycardia (AVNRT).
Methods and Results : Fifty-eight consecutive patients (aged 45 ± 12 years) with slow-fast AVNRT underwent radiofrequency catheter ablation of the slow AV nodal pathway (SP). Residual slow-fast echo beat was documented in 21 (36%) of 58 patients (group A). The pre-and postablation AH intervals triggering the echo beats were similar (346 ± 8 msec vs 352 ± 6 msec, P = NS), as were the pre-and postablation echo zones (55 ± 6 msec vs 52 ± 5 msec, P = NS) and functional refractory period of the SP. A consistent prolongation of the AV nodal effective refractory period (AVN-ERP; from 265 ± 28 msec to 340 ± 50 msec, P < 0.001) and the Wenckebach cycle length (WBCL; from 298 ± 41 msec to 438 ± 43 msec, P < 0.001) was observed in all patients with abolition of SP conduction (group B). In group A patients, the prolongation of WBCL was less (285 ± 33 msec preablation, and 334 ± 41 msec postablation, P < 0.001). Additional pulses abolished the residual echo in 16 of 21 patients, and further prolongation of the AVN-ERP and WBCL comparable to those found in patients without a residual echo beat was observed. During 19 ± 8 months follow-up, no patient had clinical recurrence of AVNRT.
Conclusion : Residual single echo beat after SP ablation for AVNRT reflects the persistence of some portion of the SP with unchanged functional conduction properties whose prognostic significance is uncertain. A consistent increase of WBCL can be a reliable marker of complete abolition of slow pathway conduction and termination of AVNRT.     

Fast pathway ablation in patients with common atrioventricular nodal reentrant tachycardia and prolonged PR interval during sinus rhythm

Aims This study aimed to clarify the safety and efficacy of selectivefast pathway ablation in patients with atrio-ventricular nodalreentrant tachycardia and a prolonged PR interval during sinusrhythm. Such patients have been reported to have an increasedincidence of complete atrioventricular block. Methods and Results In this study, the earliest retrograde atrial activation duringatrioventricular nodal reentrant tachycardia and right ventricularstimulation was localized. Fast pathway ablation was then performedin five patients with the common form of atrioventricular nodalreentrant tachycardia and a prolonged PR interval. Three ofthe five patients had almost incessant atrioventricular nodalre-entrant tachycardia. Radiofrequency catheter ablation induceda complete ventriculo-atrial block during right ventricularstimulation in four patients and a marked prolongation of ventriculo-atrialconduction during right ventricular stimulation in one. Non-inducibilityof common atrioventricular nodal reentrant tachycardia withand without isoproterenol was achieved in all five patients.The PR interval increased from 254±53ms to 276±48msand the atrio-His interval from 172±46ms to 192±45ms.Second- or third-degree atrioventricular block did not occurduring the ablation procedure. During the follow-up of 19±20months none of the patients developed symptoms suggestive ofatrioventricular nodal reentrant tachycardia or evidence ofsecond- or third-degree atrioventricular block. Conclusion These data suggest that atrioventricular node (retrograde) fastpathway ablation can apparently be safely performed in patientswith common atrioventricular nodal reentrant tachycardia anda prolonged PR interval during sinus rhythm.     

Impact of the Local Atrial Electrogram in AV Nodal Reentrant tachycardia: Abaltion Versus Modification of the Slow Pathway

Electrogram in AVNRT. Introduction: The purpose of this study was to determine the predictors of successful ablation versus modification sites of the slow pathway in patients with AV nodal reentrant tachycardia. Complete elimination of slow pathway conduction (“ablation”) is considered to be an appropriate endpoint during radiofrequency (RF) current delivery, whereas the persistence of residual slow pathway conduction with or without single echo beats (“modification”) may be indicative of tachycardia recurrence. Methods and Results: Of 131 patients, 71 consecutive patients were followed for 15.1 ± 7.6 months. After elimination of inducible AV nodal reentrant tachycardia in all patients, residual slow pathway conduction (modification) persisted in 38 patients, whereas complete elimination of slow pathway conduction (ablation) was documented in 33 patients. Including electrophysiologic study after 5 to 7 days and after 3 to 6 months, 6 (8.4%) patients had recurrences: 5 with residual slow pathway conduction after the procedure and 1 with complete elimination of slow pathway conduction (P < 0.05). As compared with modulated sites, ablation sites of the slow pathway were characterized as follows: (1) duration of the local atrial electrogram (AEGM) (66.7 ± 10.2 vs 54.1 ± 12.6 msec, P < 0.01); (2) interval from the end of the AEGM to onset of His-bundle deflection (4.4 ± 8.2 vs 16.1 ± 9.3 msec, P < 0.01); and (3) number of peaks of the AEGM as an indicator of fractionation (4.1 ± 0.7 vs 3.0 ± 0.8, P < 0.01). The rate of junctional tachycardias (103.4 ± 12.1 vs 102.1 ± 16.9 per min), the AV ratio (0.4 ± 0.5 vs 0.5 ± 0.5), the number of RF current deliveries (4.1 ± 4.4 vs 4.5 ± 4.4), the duration of the procedure (124.1 ± 45.3 vs 125.6 ± 42.3 min), and the fluoroscopy time (15.5 ± 10.8 vs 16.6 ± 9.6 min) as well as power and total energy of RF current deliveries and the anatomically calculated catheter position at the successful site were not statistically different. A subset analysis in patients who received only a single RF application showed the same results for both groups. Patients without recurrence (n = 65) were found to have longer duration of the AEGM (61.9 ± 14.6 msec) and a shorter interval from the end of AEGM to the onset of His-bundle deflection (10.1 ± 12.2 msec) than patients with recurrence (n = 6) (47.5 ± 7.5 msec and 20.8 ± 12.8 msec, respectively). Conclusion: Complete ablation of the slow pathway resulted in a lower recurrence rate. The complete ablation approach is feasible using precisely analyzed local AEGMs to guide RF current in AV nodal reentrant tachycardia in a short procedure time.     

Atrioventricular Nodal Reentrant Tachycardia with Multiple Discontinuities in the Atrioventricular Node Conduction Curve: Immediate Success Rates of Radiofrequency Ablation and Long-Term Clinical Follow-up Results as Compared to Patients with Single or No AH-Jumps

Background: Some patients with atrioventricular nodal reentrant tachycardia (AVNRT) demonstrate multiple discontinuities (AH jump) in their antegrade AV node conduction curves. We evaluated and compared the immediate success rates, procedure-related complications, long-term clinical follow-up results and recurrence rates after slow pathway ablation in patients with multiple versus single or no AH jumps. Methods: The study group consists of 278 consecutive patients (mean age 36.6 ± 15.7) who underwent ablation for typical AVNRT, divided into three categories according to the number of AH jumps (50 ms) before ablation: Group-1 consisted of 63 patients (23%) with continuous AV node function curves; Group-2 of 183 patients (66%) with a single jump and Group-3 of 32 (12%) patients showing more than one AH jumps. Results: Age was significantly higher in Group-3 as compared to Group-1 (43 ± 18 years vs. 34 ± 16 years, p = 0.020). The electrophysiological features of AVNRT did not differ among groups. Before ablation, the maximum AH interval was significantly longer in Group-3 as compared to Groups-1 and -2 (p < 0.001 for both). AV node antegrade ERP was significantly shorter in Group-3 than in Group-2, both before and after ablation (p < 0.050 for both). AV node Wenckebach cycle length (WCL) was shorter in Group-3 as compared to both Groups-1 and -2, before and after ablation (p < 0.050 for all). AV node WCL was prolonged significantly in all groups after ablation (p < 0.001 for all). Residual dual pathways were present in 37 of 278 patients (13%) after ablation and were significantly more frequent in Group-3 than Group-2 (31% vs. 15%, p = 0.023). Conclusions: Patients with multiple AH jumps are older and more often have residual dual atrioventricular nodal pathway physiology after successful ablation but these features do not affect the immediate and long-term success rates of slow pathway ablation as compared to patients with single or no AH jumps.