Shortcut Link Between the Fast and Slow Pathways and the Mechanism of Cure in Atrioventricular Nodal Reentrant Tachycardia by Catheter Ablation

The mechanism of cure in AV nodal reentrant tachycardia (AVNRT) by catheter ablation has not been fully clarified. We hypothesized that disruption of a shortcut link between the fast and slow pathways is responsible for the elimination of tachycardia. Results: AVNRT was eliminated in 20 patients by catheter ablation. In five patients (25%; group 1) slow pathway conduction disappeared 1 week after ablation. In six patients (30%; group II), the effective refractory period of the slow pathway was prolonged by more than 50 ms (212 ± 81 ms vs 340 ± 81 ms; P < 0.05). In the remaining nine patients (45%; group III), there was no change in the refractory period (270 ± 65 ms vs 273 ± 74 ms), although tachycardia was not inducible. A shortcut link between the fast and slow pathways was examined by comparing the A-H intervals over the slow pathway during the tachycardia and during atrial pacing at the tachycardia cycle length. Prior to ablation, a shortcut link was assumed in 1 of group I patients, 2 of group II patients, and 8 of group III patients. Of the 9 patients in whom the slow pathway was not impaired after ablation (group III), 8 patients were found to have a shortcut link, while 8 of 11 patients with impairment of the slow pathway after ablation (groups I and II) had no shortcut link between the fast and slow pathways (P < 0.05). Conclusion: In patients with a shortcut link between the fast and slow pathways, slow pathway conduction itself does not need to be impaired to eliminate the AVNRT, whereas in patients without this shortcut link, slow pathway conduction must be impaired.     

Abnormal Atrioventricular Node Conduction and Atrioventricular Nodal Reentrant Tachycardia in Patients Older Versus Younger Than 65 Years of Age

Study Objective: We examined the possible role of atrioventricular node (AVN) conduction abnormalities as a cause of AVN reentrant tachycardia (RT) in patients >65 years of age.
Study Population: Slow pathway radiofrequency catheter ablation (RFCA) was performed in 104 patients. Patients in group 1 (n = 14) were >65 years of age and had AV conduction abnormalities associated with structural heart disease. Patients in group 2 (n = 90) were <65 years of age and had lone AVNRT.
Results: Patients in group 1 versus group 2 (66% vs. 46% men) had a first episode of tachycardia at an older age than in group 2 (68 ± 16.8 vs 32.5 ± 18.8 years, P = 0.007). The history of arrhythmia was shorter in group 1 (5.4 ± 3.8 vs 17.5 ± 14, P = 0.05) and was associated with a higher proportion of patients with underlying heart disease than in group 2 (79% vs 3%, P < 0.001). The electrophysiological measurements were significantly shorter in group 2: atrial-His interval (74 ± 17 vs 144 ± 44 ms, P = 0.005), His-ventricular (HV) interval (41 ± 5 vs 57 ± 7 ms, P = 0.001), Wenckebach cycle length (329 ± 38 vs 436 ± 90 ms, P = 0.001), slow pathway effective refractory period (268 ± 7 vs 344 ± 94 ms, P = 0.005), and tachycardia cycle length (332 ± 53 vs 426 ± 56 ms, P = 0.001). The ventriculoatrial block cycle length was similar in both groups. The immediate procedural success rate was 100% in both groups, and no complication was observed in either group. One patient in group 2 had recurrence of AVNRT. One patient with a 98-ms HV interval underwent permanent VVI pacemaker implantation before RFCA procedure.
Conclusion: In patients undergoing RFCA for AVNRT at >65 years of age had a shorter history of tachycardia-related symptoms than patients with lone AVNRT. The longer AVN conduction intervals and refractory period might explain the late development of AVNRT in group 1.     

Radiofrequency Ablation of Pediatric AV Nodal Reentrant Tachycardia during the Ice Age: A Single Center Experience in the Cryoablation Era

Background: Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) has proven to be an effective therapy in the pediatric population. However, concerns of inadvertent permanent AV nodal block have resulted in many pediatric programs adopting cryoablation as their primary ablation approach for AVNRT.
Methods: A retrospective analysis of the results of pediatric radiofrequency catheter ablation at a single institution over the most recent 5 years (January 2004 through December 2008) was performed. Acute, intermediate, and long-term success, along with the incidence of AV block, were determined.
Results: There were 65 patients with a mean age of 12.1 ± 5.2 years and weight of 46.5 ± 17.3 kg who underwent radiofrequency catheter ablation for AVNRT. There was 100% acute success with no recurrences at a mean follow up of 32.5 months. Although two patients had a brief second-degree AV block, there was no permanent AV block of any degree.
Conclusions: The safety and efficacy of radiofrequency catheter ablation for pediatric AVNRT demonstrated in this study support its continued application and should not be abandoned as a method of treatment. (PACE 2010; 6–10)     

Entrainment to Distinguish Orthodromic Reciprocating Tachycardia from Atrioventricular Nodal Reentry Tachycardia in Children

Background : Studies in adults suggest that after entrainment from the right ventricle, a post‐pacing interval (PPI) minus tachycardia cycle length (TCL), when corrected for atrioventricular node delay (cPPI‐TCL), is useful to distinguish atrioventricular nodal reentry tachycardia (AVNRT) from orthodromic reciprocating tachycardia (ORT), but this has not been evaluated in children. Methods : In 100 children undergoing catheter ablation, entrainment of ORT or AVNRT was performed from the right ventricular apex. The atrial‐His (AH) interval was measured on the return cycle (post‐AH) and during tachycardia just prior to pacing (pre‐AH). The cPPI‐TCL was calculated as (PPI‐TCL) ? (post‐AH ? pre‐AH). In the first 50 children, the best cutoff was identified and then validated in the next 50 children. Results : In the first 50 children, cPPI‐TCL was longer in AVNRT compared with ORT (122 ± 19 ms vs 63 ± 23 ms, P < 0.001). Furthermore, cPPI‐TCL exceeded 95 ms in all AVNRT patients, but was less than < 95 ms in 28 of 29 ORT patients. In the next 50 children, a cPPI‐TCL < 95 ms was 100% specific for ORT; a cPPI‐TCL > 95 ms was 95% specific for AVNRT. There was even greater separation of cPPI‐TCL values comparing AVNRT with ORT utilizing a septal accessory pathway. Conclusions : The cPPI‐TCL is a useful technique to distinguish AVNRT from ORT in children. Our data suggest that in children a cPPI‐TCL < 95 ms excludes AVNRT, while a value > 95 ms is rarely observed in ORT. This technique is particularly useful to distinguish AVNRT from ORT utilizing a septal accessory pathway. (PACE 2010; 469–474)     

Localized reentry as a novel type of the proarrhythmic effects of linear ablation in the left atrium

Background: There is a consistent understanding that the proarrhythmic effect of linear ablation in the left atrium body for atrial fibrillation (AF) always manifests as the macroreentry tachycardia. However, its genesis of localized reentry has been underestimated. Methods: Among 90 persistent AF patients who had accepted linear ablation in the left atrium body, a total of 11 patients (12%) presented with a localized reentry (six men, mean age 59 ± 11 years) associated with previous ablation lines. Among the 11 patients, four were encountered during the index procedure for AF ablation and the remaining seven during the redo procedure for atrial tachycardias (ATs). Results: The ATs were all located at previously ablated lesion sites and manifested a centrifugal mode in both the activation mapping and pattern of the postpacing interval response. The mean tachycardia cycle length (TCL) of the localized reentrant ATs was 306 ± 73 ms. The target sites demonstrated low amplitude (0.17 ± 0.09 mV) continuous complex electrograms or long double potentials, covering 142 ± 57 ms (46 ± 12 % of the TCL). The localized reentrant tachycardias were all successfully eliminated by catheter ablation. Conclusions: A novel type of the proarrhythmic effects of linear ablation in the left atrium for AF may manifest as localized reentrant ATs, as evidenced by the association of the site of origin with the prior lesions. (PACE 2011; 34:919–926)     

A Direct Midseptal Approach to Slow Atrioventricular Nodal Pathway Ablation

Objectives: The purpose of this study was to describe a midseptal approach to selective slow pathway ablation for the treatment of AV nodal reentrant tachycardia (AVNRT). In addition, predictors of success and recurrence were evaluated. Methods: Selective ablation of the slow AV nodal pathway utilizing radiofrequency (RF) energy and a midseptal approach was attempted in 60 consecutive patients with inducible AVNRT. Results: Successful slow pathway ablation or modification was achieved in 59 of 60 patients (98%) during a single procedure. One patient developed inadvertent complete AV block (1.6%). A mean of 2,7 ±1.4 RF applications were required with mean total procedure, ablation, and fluoroscopic times of 191± 6.3, 22.8 ± 2.3, and 28.2 ±1.8 minutes, respectively. The PR and AH intervals, as well as the antegrade and retrograde AV node block cycle length, were unchanged. However, the fast pathway effective refractory period was significantly shortened following ablation (354± 13 msec vs 298 ± 12 msec; P= 0.008). The A/V ratio at successful ablation sites were no different than those at unsuccessful sites (0.22 ± 0.04 vs 0.23± 0.03). Junctional tachycardia was observed during all successful and 60 of 122 (49%) unsuccessful RF applications (P < 0.0001). A residual AV nodal reentrant echo was present in 15 of 59 (25%) patients, During a mean follow-up of 20.1± 0.6 months (11.5–28 months) there were four recurrences (5%), 4 of 15 (27%) in patients with and none of 44 patients without residual slow pathway conduction (P = 0.002). Conclusions: A direct midseptal approach to selective ablation of the slow pathway is a safe, efficacious, and efficient technique. Junctional tachycardia during RF energy application was a highly sensitive but not specific predictor of success and residual slow pathway conduction was associated with a high rate of recurrence.     

Effects of Pharmacological Autonomic Blockade on Dual Atrioventricular Nodal Pathways Physiology in Patients with Slow-Fast Atrioventricular Nodal Reentrant Tachycardia

The purpose of this study was to investigate the atrioventricular AV nodal physiology and the inducibility of AV nodal reentrant tachycardia (AVNRT) under pharmacological autonomic blockade (AB). Seventeen consecutive patients (6 men and 11 women, mean age 39 ± 17 years) with clinical recurrent slow-fast AVNRT received electrophysiological study before and after pharmacological AB with atropine (0.04 mg/kg) and propranolol (0.2 mg/kg). In baseline, all 17 patients could be induced with AVNRT, 5 were isoproterenol-dependent. After pharmacological AB, 12 (71 %) of 17 patients still demonstrated AV nodal duality. AVNRT became noninducible in 7 of 12 nonisoproterenol dependent patients and remained noninducible in all 5 isoproterenol dependent patients. The sinus cycle length (801 ± 105 ms vs 630 ± 80 ms, P < 0.005) and AV blocking cycle length (365 ± 64 ms vs 338 ± 61 ms, P < 0.005) became shorter after AB. The antegrade effective refractory period and functional refractory period of the fast pathway (369 ± 67 ms vs 305 ± 73 ms, P < 0.005; 408 ± 56 ms vs 350 ± 62 ms, P < 0.005) and the slow pathway (271 ± 30 ms vs 258 ± 27 ms, P < 0.01; 344 ± 60 ms vs 295 ± 50 ms, P < 0.005) likewise became significantly shortened. However, the ventriculoatrial blocking cycle length (349 ± 94 ms vs 326 ± 89 ms, NS) and effective refractory period of retrograde fast pathway (228 ± 38 ms vs 240 ± 80 ms, NS) remained unchanged after autonomic blockade. Pharmacological AB unveiling the intrinsic AV nodal physiology could result in the masking of AV nodal duality and the decreased inducibility of clinical AVNRT.     

An Increase in Sinus Rate Following Radiofrequency Energy Application in the Posteroseptal Space

An increase in sinus rate has been previously described in patients with AV node reentry (AVNRT) following successful A V node modification. This increase could either be a specific sign of elimination of slow pathway conduction or it could be a consequence of energy application in the posteroseptal area. Thus, we compared the changes in sinus cycle length following successful slow pathway ablation (defined as complete elimination of dual AV node physiology) in patients having AVNRT with those in patients undergoing successful ablation of a posteroseptal atriovetriricular accessory connection. Twenty five patients (16 women and 9 men, mean age 41 ± 4 years) with typical AVNRT (cycle length 378 ± 12 ms and 29 patients (16 women and 13 men, age 34 ± 5 years) with an accessory connection (17 manifest and 12 concealed) were studied. The electrophysiology study was performed during sedation with Fentanyl and Midazolam. The mean number of energy applications was 3 ± 1 for successful slow pathway ablation and 4 ± 1 for successful ablation of the accessory connection (p:NS). Following the successful energy application, the sinus cycle length decreased significantly 776 ms at baseline to 691 ms in patients with AVNRT. Following successful ablation of the posteroseptal AC, sinus cycle length decreased from 755 ms at baseline to 664 ms (p < 0.05 in both groups [difference between groups not significant]). The decrease in sinus cycle length did not correlate with the number ofRF energy applications required for successful ablation or the total energy delivered. In conclusion, ablation of the AV node slow pathway and a posteroseptal accessory connection results in similar increases in the sinus rate. Thus, the increase in sinus rate is probably due to energy application in the posteroseptal space, possibly due to concomitant destruction of vagal inputs, and it is not specific for elimination of slow pathway conduction.     

The different ablation effects on atrioventricular nodal reentrant tachycardia in children with and without dual nodal pathways

BACKGROUND: Previous studies in adults have shown a significant shortening of the fast pathway effective refractory period (ERP) after successful slow pathway ablation. However, information on atrioventricular nodal reentrant tachycardia (AVNRT) in children is limited. The purpose of this retrospective study was to investigate the different effects of radiofrequency (RF) catheter ablation in pediatric AVNRT patients between those with and without dual atrioventricular (AV) nodal pathways. METHODS: From January 1992 to August 2004, a total 67 pediatric patients with AVNRT underwent an electrophysiologic study and RF catheter ablation at our institution. We compared the electrophysiologic characteristics between those obtained before and after ablation in the children with AVNRT with and without dual AV nodal pathways. RESULTS: Dual AV nodal pathways were found in 37 (55%) of 67 children, including 36 (54%) with antegrade and 10 (15%) with retrograde dual AV nodal pathways. The antegrade and retrograde fast pathway ERPs in children with dual AV nodal pathways were both longer than the antegrade and retrograde ERPs in children without dual AV nodal pathways (300 +/- 68 vs 264 +/- 58 ms, P = 0.004; 415 +/- 70 vs 250 +/- 45 ms, P < 0.001) before ablation. In children with antegrade dual AV nodal pathways, the antegrade fast pathway ERP decreased from 300 +/- 68 ms to 258 +/- 62 ms (P = 0.008). The retrograde fast pathway ERP also decreased after successful ablation in the children with retrograde dual AV nodal pathways (415 +/- 70 vs. 358 +/- 72 ms, P = 0.026). CONCLUSION: The dual AV nodal physiology could not be commonly demonstrated in pediatric patients with inducible AVNRT. After a successful slow pathway ablation, the fast pathway ERP shortened significantly in the children with dual AV nodal pathways.     

Intracardiac echocardiography-guided his bundle pacing and atrioventricular nodal ablation

Background: His bundle pacing (HBP) results in rapid synchronous ventricular activation, but has been associated with long procedure times and compromised pacing and sensing performance. This study sought to reduce procedure time and radiation exposure, and improve electrical performance through more accurate lead placement.
Methods: Intracardiac echocardiography (ICE) was used to guide ablation and lead implantation at the His bundle, right atrial appendage (RAA), and right ventricular apex (RVA), and to assess cardiac function. Custom bipolar screw-in leads with steerable delivery sheaths and an ablation catheter were navigated using ICE (local detailed imaging) and fluoroscopy (global imaging) in anesthetized closed-chest canines (N = 6).
Results: HBP (N = 1) or His + ventricular septal pacing (N = 5) was achieved in all canines. The QRS width was 59.7 ± 5.3 ms for canines in sinus rhythm (SR) and 82.8 ± 16.6 ms for canines with HBP (P = 0.0086). The QRS width for RVA pacing was 106.3 ± 18.4 ms (P = 0.042 vs HBP; P = 0.00013 vs SR). HBP thresholds were 3.0 ± 1.0 volts at 0.5 ms (N = 5 due to a late exit block in one canine). The average procedure duration for His lead placement was 40 ± 28 minutes (range of 3–81 minutes) and the total procedural X-ray exposure was 12 ± 12 minutes (range of 2–30 minutes). Hemodynamic performance was similar for HBP and RAA pacing.
Conclusions: Feasibility of ICE guidance for His pacing and precision ablation of the atrioventricular (AV) node has been shown. This anatomic approach improved accuracy, limited X-ray exposure, and might allow His pacing in patients with preexisting AV nodal block.     

Decremental ramp atrial extrastimuli pacing protocol for the induction of atrioventricular nodal re-entrant tachycardia and other supraventricular tachycardias

AIM: The primary aim of this study was to evaluate the utility of decremental ramp atrial extrastimuli pacing protocol (PRTCL) for induction of atrioventricular nodal re-entrant tachycardia (AVNRT), and other supraventricular tachycardias (SVTs), compared to standard (STD) methods. METHODS: The study cohort of 121 patients (age 57.51 +/- 14.02 years) who presented with documented SVTs and/or symptoms of palpitations and dizziness, and underwent invasive electrophysiological evaluation was divided into Group I (AVNRT, n = 42) and Group II (Control, n = 79). The PRTCL involved a train of six atrial extrastimuli, delivered in a decremental ramp fashion. The STD methods included continuous burst and rapid incremental pacing up to atrioventricular (AV) block cycle length, and single and occasionally double atrial extrastimuli. Prolongation in the Atrio-Hisian (Delta-AH) intervals achieved by both methods were compared, as were induction frequencies. RESULTS: In Group I, three categories of responses--(1) induction of AVNRT, (2) induction of echo beats only, and (3) none--were observed in 29 (69%), 11 (26%), and 2 (5%) patients with the PRTCL, when compared with 14 (33%), 16 (38%), and 12 (29%) patients with STD methods in the baseline state without the use of pharmacological agents. The Delta-AH intervals for each of these three categories were larger using PRTCL versus STD methods; 293.3 +/- 95.2 ms versus 192.9 +/- 61.4 ms (P < 0.005), 308.6 +/- 68.5 ms versus 189. 9 +/- 64.9 ms (P < 0.0005), and 203.0 +/- 86.3 ms versus 145.8 +/- 58.9 ms (P = NS), respectively. In Group II, in one patient with dual AV nodal physiology but no clinical tachycardia, the PRTCL induced nonsustained (12 beats) AVNRT. Additionally, in this group, both PRTCL and STD methods induced atrial tachycardia in two patients and orthodromic AV re-entrant tachycardia in one patient. CONCLUSION: Decremental ramp atrial extrastimuli pacing PRTCL demonstrates a superior response for induction of typical AVNRT as compared to STD techniques. Because of easy and reliable induction of AVNRT and echo beats by the PRTCL, we recommend it as a method to increase the likelihood of induction of AVNRT. For induction of other SVTs, the PRTCL and the STD methods are comparable.     

Coexistence of Atrioventricular Nodal Reentrant Tachycardia with Other Forms of Arrhythmias

Objective

The aim of this retrospective study was to investigate the association of atrioventricular nodal reentrant tachycardia (AVNRT) with other forms of arrhythmia in individual patients and its consequences for treatment.

Subjects and Methods

This study comprised 493 consecutive patients aged 16–88 years (296 women and 197 men) who were diagnosed with a form of AVNRT via a standard 4-catheter electrophysiological study (EPS). Patients were clinically followed (range 0.5–12 years) at a single center.

Results

Coexistence of AVNRT with other types of tachycardias was observed in 197 (40%) patients. Atrial fibrillation was found most frequently in 94 (19%) patients as follows: focal atrial tachycardia, n = 40 (8%); atrial flutter, n = 32 (6%), and AV reentrant tachycardia, n = 22 (4%). Double tachycardia was present in 140 (30%) patients, and more than 2 different types of tachycardias were present in 57 (12%) patients. Transitions between AVNRT and other tachycardias occurred in 25 (5%) patients. Two or more tachycardias were ablated in 42 (9%) patients. The majority of patients were free of symptoms at the first follow-up, whereas 130 (26%) patients reported a variety of symptoms.

Conclusion

Coexistence of AVNRT with other types of arrhythmias was a common finding among these patients. The most frequently observed double tachycardia was the combination of AVNRT with atrial tachyarrhythmias, such as atrial fibrillation, with a potential significance for further patient management.Key Words: Supraventricular tachycardia, Atrioventricular nodal reentrant tachycardia, Electrophysiological study, Radiofrequency catheter ablation, Atrial fibrillation     

Remote magnetic navigation-assisted catheter ablation enhances catheter stability and ablation success with lower catheter temperatures

Background: It has been suggested that remote magnetic navigation (RMN) may provide enhanced catheter stability and substrate contact to aid in ablation. To date, no study has examined this claim. Accordingly, we compared the characteristics of the successful ablation of atrioventricular reentry tachycardia (AVNRT) using RMN with a matched population ablated using a conventional (CON) manual approach.
Methods: Sixteen patients who underwent RMN-assisted ablation of typical AVNRT were matched with 16 patients who had a CON-AVNRT ablation.
Results: All patients had successful slow pathway modification without complication. The mean catheter temperature achieved with the successful ablation was significantly lower with RMN than with CON (42 ± 7°C vs 47 ± 3°C, P ≤ 0.05). Time to junctional tachycardia (JT) was significantly earlier (5.7 ± 4.1 s vs 11.2 ± 8.9 s, P ≤ 0.05) and variation in catheter temperature with the successful ablation (0.89 ± 0.45 vs 1.45 ± 0.49, P < 0.01) was significantly reduced in the RMN group than in the CON group. There was no significant difference between RMN and CON in terms of the total number of lesions and the mean power achieved during the successful lesion.
Conclusions: Although the construction of the ablation catheters is similar, ablations with RMN catheters resulted in a lower mean temperature, earlier time to JT, and less variability of temperature during ablation, suggesting greater catheter stability. This study indicates that ablation with RMN can achieve success with lower catheter temperatures.     

Electrophysiological Behavior of Atrioventricular Node After Selective Fast or Slow Pathway Ablation in Patients with Atrioventricular Nodal Reentrant Tachycardia

One hundred twenty consecutive patients with symptomatic atrioventricular nodal reentrant tachycardia (AVNRT) underwent catheter ablation using radiofrequency energy. Fast pathway ablation was attempted in the first 16 consecutive patients by application of radiofrequency current in the anterior and superior aspect of the tricuspid annulus. Successful results were accomplished in 13 patients, complete atrioventricular (AV) block occurred in three. One hundred four patients underwent ablation of the slow pathway in the posterior and inferior aspect of the tricuspid annulus, which was successful in 98 patients. The remaining six patients subsequently underwent a fast pathway ablation with successful results in four and AV block in two. Therefore. 102 (98%) of the last 104 patients became free of AVNRT while maintaining intact AV conduction. This study characterizes the electrophysiological properties of the residual AV node following a selective fast or slow pathway ablation.     

Changes in AV Node Conduction Curves Following Slow Pathway Modification

GELLER, J.C., et al. : Changes in AV Node Conduction Curves Following Slow Pathway Modification. Dual AV node physiology often persists after successful slow pathway (SP) ablation, and the mechanism of tachycardia elimination is unresolved. Therefore, AV node conduction curves were analyzed following successful ablation (  4 ± 1  energy applications) in 85 consecutive patients (58 women, age  50 ± 2  years) with typical AVNRT. Twenty-seven patients (32%) had complete elimination (group 1) whereas 58 (68%) patients had persistence (group 2) of dual AV node physiology. A significant increase in the AV node Wenckebach cycle length (WB-CL) was observed in both groups (  310 ± 9 to 351 ± 15 ms  in group 1, and  325 ± 8 to 369 ± 9 ms  in group  2, P < 0.05  ). A decrease in the fast pathway (FP) ERP (  339 ± 15 to 279 ± 12 ms  ) and an increase in the maximum FP AH interval (  141 ± 5 to 171 ± 7  ) were observed only in group 1 (P < 0.05). In group 2, no change in the SP ERP (  267 ± 7 to 280 ± 10 ms  ) was observed, and the change in the maximum SP-AH following ablation showed a significant inverse relation to the maximum SP-AH at baseline in group 2. In conclusion, (1) an increase in the WB-CL is observed independent of the persistence or elimination of dual physiology after successful ablation; (2) when dual physiology is eliminated, significant changes in the FP ERP and the maximum FP-AH occur; (3) when dual physiology persists, FP physiology and the SP ERP remain unchanged, and a significant inverse relation between the change in the maximum SP-AH following ablation and the maximum baseline SP-AH is observed.     

冠状窦呈偏心性激动的不典型房室结折返性心动过速的电生理特征及导管消融

目的 总结冠状窦（coronary sinus, CS）呈偏心性激动的不典型房室结折返性心动过速（atrioventricular nodal reentry tachycardia, AVNRT）的电生理特点、鉴别诊断及消融方法。方法 回顾性收集2014年1月至2018年12月在复旦大学附属中山医院心内科进行射频消融治疗的524例AVNRT患者的临床资料。其中,CS呈偏心性激动的不典型AVNRT患者共16例,男性6例、女性10例,平均年龄（56.6±11.4）岁。分析16例不典型AVNRT患者的体表心电图和腔内心电图特点、诱发方式、鉴别诊断及射频消融策略。结果 16例CS呈偏心性激动的AVNRT患者的心电图均表现为RP间期>PR间期,P波在Ⅱ、Ⅲ、aVF导联中倒置;发作时12例患者房室传导比例为1∶1,4例患者为2∶1或3∶1;13例患者可以轻易通过心室拖带的方式进行鉴别,2例患者需要多次拖带才能成功,1例患者多次拖带下心房-心室（atrioventricular,VA）仍然分离;14例患者在右心房后间隔靠近三尖瓣环处成功消融,3例患者在CS内成功消融。结论 CS呈偏心性激动的...     

Clinical experience with electroanatomic mapping of ectopic atrial tachycardia

The aim of this study was to evaluate the clinical use of a new three-dimensional mapping system as a guide for catheter ablation of ectopic atrial tachycardia. A series of 42 consecutive patients with drug refractory ectopic atrial tachycardia was studied in a prospective observational trial with the electroanatomic mapping system CARTO. The arrhythmogenic focus was found in the right atrium in 30 patients and in the left atrium in 12 patients. The construction of a complete electroanatomic map of the right or left atrium was possible in 37 of 42 consecutive patients with ectopic atrial tachycardia. Mean activation time of the right atrium, including the proximal coronary sinus, was 94 +/- 25 ms for right atrial tachycardias; left atrial activation time during left atrial tachycardias was 86 +/- 17 ms. Average mapping time was 30 minutes for right atrial tachycardias and 22 minutes for left atrial tachycardias, allowing the collection of 86 +/- 50 and 65 +/- 28 catheter positions, respectively. The size of the area of earliest atrial activation calculated from the electroanatomic map amounted to 0.6 +/- 0.4 cm2 in right atrial tachycardias and 1.0 +/- 0.9 cm2 in left atrial tachycardias. In the right atrium the most common locations of the 33 arrhythmogenic foci in 30 patients were the high or mid-lateral right atrium (n = 10) and the inferoparaseptal region near the coronary sinus ostium (n = 7). Ectopic left atrial foci were most commonly located in an inferior position near the mitral annulus (n = 5) and in proximity to the ostium of the pulmonary veins (n = 4). Biatrial electroanatomic mapping allowed visualization of earliest right atrial activation during left atrial tachycardia at the high interatrial septum or near the coronary sinus ostium. Catheter ablation was successful in 85% of right atrial tachycardias and 82% of left atrial tachycardias. In patients with ectopic atrial tachycardia electroanatomic mapping is a safe and feasible technique that allows three-dimensional visualization of the automatic focus in a precise anatomic reconstruction of the atria. This novel mapping technology facilitates catheter ablation of complex ectopic atrial tachycardia.     

Cryoablation for atrioventricular nodal reentrant tachycardia in young patients: predictors of recurrence

Background: Recurrence rates of atrioventricular nodal reentry tachycardia (AVNRT) after cryoablation continue to remain high despite excellent initial success rates. Our objective was to evaluate the clinical outcomes of cryoablation for AVNRT with the 4-mm and 6-mm tip cryoablation catheters in a young population and to elicit predictors of arrhythmia recurrence.
Methods: We retrospectively reviewed all patients who underwent cryoablation for AVNRT at the UCSF/Stanford Pediatric Arrhythmia Center from January 2004 to February 2007.
Results: One hundred fifty-four patients (age 13.7 years (3.2–24.4)) underwent cryoablation for AVNRT of which 144 patients had inducible AVNRT (123 sustained and 21 nonsustained) and 10 had presumed AVNRT. Initial success was achieved in 95% (146/154), with no difference between the 4-mm (93%) and 6-mm (98%) cryoablation catheter tips (P = 0.15). There was no permanent atrioventricular (AV) block. Transient third-degree AV block occurred in nine patients (6%), with no difference between the 4-mm (4%) and 6-mm (9%) tip (P = 0.13). AVNRT recurrence was documented in 14% in a median time of 2.5 months (0.25–20). Recurrences were lower with the 6-mm (9%) versus the 4-mm (18%) tip, but this did not reach statistical significance (P = 0.16). With univariate analysis, a longer fluoroscopy time was the only significant factor associated with recurrence. Multivariate analysis failed to identify any significant predictor of AVNRT recurrence.
Conclusion: Outcomes of cryoablation for AVNRT continue to be good without the complication of AV block. We could not identify any specific parameter associated with AVNRT recurrence. Further improvements in cryoablation technique will be necessary to reduce recurrences.     

The results of radiofrequency catheter ablation of supraventricular tachycardia in children

BACKGROUNDS: Radiofrequency (RF) catheter ablation represents a major advance in the management of children with cardiac arrhythmias and has rapidly become the standard of care for the first-ling therapy of supraventricular tachycardias (SVTs). The purpose of this study was to investigate the results of the RF catheter ablation of SVTs in pediatric patients. METHODS: From December 1989 to August 2005, a total of 228 pediatric patients (age: 9 +/- 7 years, range: 5-18 years; male:female = 117:111) with clinically documented SVT underwent an electrophysiologic study and RF catheter ablation at our institution. RESULTS: The arrhythmias included atrioventricular reentrant tachycardia (AVRT; n = 140, 61%), atrioventricular nodal reentrant tachycardia (AVNRT; n = 66, 29%), atrial tachycardia (AT; n = 11, 5%), and atrial flutter (AFL; n = 11, 5%). The success rate of the RF catheter ablation was 92% for AVRT, 97% for AVNRT, 82% for AT, and 91% for AFL, respectively. Procedure-related complications were infrequent (8.7%; major complications: high grade AV block (2/231, 0.9%); minor complications: first degree AV block (6/231, 2.6%), reversible brachial plexus injury (2/231, 0.9%), and local hematomas or bruises (10/231, 4.3%)). The recurrence rate was 4.7% (10/212) during a follow-up period of 86 +/- 38 months (0.5-185 months). CONCLUSIONS: The RF catheter ablation was a safe and effective method to manage children with paroxysmal and incessant tachycardia. The substrates of the arrhythmias differed between the pediatric and adult patients. However, the success rate of the ablation, complications, and recurrence during childhood were similar to those of adults.     

Atrio-Pulmonary Vein Conduction Delay during Pulmonary Vein Isolation for Atrial Fibrillation Is Related to Vein Anatomy, Age, and Focal Activity

Background: During pulmonary vein isolation for treatment of atrial fibrillation (AF), a significant delay in atrio-pulmonary vein (PV) conduction is often observed. We sought to investigate this conduction delay in various PV in individual patients.
Methods: We studied 385 AF patients (mean age: 54 ± 11 years, 74 women) who underwent segmental PV isolation (PVI). A circular decapolar catheter was used to record electrograms at the PV ostia. The time delay from local atrial potential to PV potential was measured in each vein. Conduction delay (CD) was defined as the longest time interval >20 ms observed during PVI.
Results: For patients treated for the first time, CD was more frequently observed in the left common and the right and left superior PVs (84.2%, 67.9%, and 66.2%, respectively) and less frequently in the left and right inferior and right middle PVs (54.3%, 40.0%, and 30.8%, respectively). Veins with CD required more ablation applications (12.4 vs 9.9) and a higher ablated segmental fraction (72.3% vs 63.7%). CD was observed in 75.2% (109/145) of the PVs in which focal activity was detected. Older patients had a higher incidence of PVs with CD than younger patients. There were no gender differences.
Conclusions: The incidence of CD was highest in the left common and superior PVs, in older patients and in PVs with focal activity. PVs with CD required more ablation applications and a larger area of ablation around the ostia. These observations were not found during repeat procedures.