3D Non-Fluoroscopic Cryoablation of Right-Sided Accessory Pathways in Children: Monocentric Study and Literature Review

Background: Cryoablation of accessory pathways (APs) is effective and very safe in children, as previously reported by our group. The aim of this retrospective study was to evaluate the current efficacy of 3D non-fluoroscopic cryoablation of right sided APs in children, comparing results obtained with the Ensite Velocity^TM and the more recent Ensite Precision^TM 3D mapping systems. Methods and Results: From January 2016 to December 2019, 102 pediatric patients [mean age 12.5 ± 2.8, 62 males (61% of total cohort)] with right APs underwent 3D non-fluoroscopic transcatheter cryoablation at our Institution. Fifteen (14.7%) patients had previously undergone catheter ablation. Acute procedural success rate was 95.1% (n = 97). No significant differences were detected in acute success rates achieved with Ensite Velocity^TM or Ensite PrecisionTM systems nor between manifest (94%) and concealed APs (100%). No permanent complications occurred. During follow-up (428 ± 286 days, median 396 days [interquartile range 179-713]), 19 patients (19.6%) had recurrences. Recurrences were more frequent for parahissian/anterior APs compared to midseptal/posterior and lateral APs (p = 0.043). Recurrences were not related to the Ensite system used. A redo ablation procedure was attempted in 13 cases, 11 cryoablation and 2 radiofrequency ablations: the former was successful in 10 cases out of 11 (90.9%). Conclusion: 3D cryoablation of right-sided APs is associated with a very high acute success rate with limited use of fluoroscopy, resulting in great benefit to the children. Recurrence rates are not high and patients can be retreated with cryo-energy with higher success rates.     

Radiofrequency Catheter Ablation of Accessory Pathways:

RF Catheter Ablation of APs. Catheter ablation techniques are now advocated as the first line of therapy for arrhythmias caused by accessory pathways (APs). The most common energy source is radiofrequency current, but technical characteristics vary. Several parameters can be used to determine the optimal target site: AP potential, AV time, atrial or ventricular insertion site, or unipolar morphology. Specific considerations are needed depending on AP location. Despite the different approaches described, there is no significant difference in the reported success rate, which is over 90%. However, the number of radiofrequency applications needed to achieve ablation appears to differ significantly, with median values from 3 to 8 reported. A combination of criteria related to both timing and direction of the activation wave-front or use of subthreshold stimulation could improve the accuracy of mapping. In patients with "resistant" APs, different changes in ablation technique must be considered during the procedure to achieve elimination of AP conduction. The incidence of complications in multi-center reports is close to 4%, with a recurrence rate of 8%. The long-term safety of catheter ablation requires further study.     

Identification of Fiber Orientation in Left Free-Wall Accessory Pathways: Implication for Radiofrequency Ablation

Previous reports on the anatomic discordance between atrial andventricular insertion sites of left free-wall accessory pathways werelimited and their findings were controversial. The purpose of this studywas to explore the fiber orientation and related electrophysiologiccharacteristics of left free-wall accessory pathways. The study populationcomprised 96 consecutive patients with a single left free-wall accessorypathway (33 manifest and 63 concealed pathways), who underwentelectrophysiologic study and radiofrequency catheter ablation using theretrograde ventricular approach. The atrial insertion site of the accessorypathway was defined from the cinefilms as the site with the earliestretrograde atrial activation bracketed on the coronary sinus catheterduring tachycardia, and the ventricular insertion site was defined as thesite where successful ablation of the pathway was achieved. Forty-twopatients (44%) had their atrial insertion sites 5-20 mm (10 ±3 mm) distal to the ventricular insertion sites (proximal excursion), 30(31%) patients had their atrial insertion sites 5-20 mm (12 ±3 mm) proximal to the ventricular insertion sites (distal excursion), and24 (25%) patients had directly aligned atrial and ventricular insertion sites. Retrograde conduction properties, including 1:1 VA conduction and effective refractory period, were significantly poorer inthe pathways with proximal excursion (302 ± 67, 285 ± 61 msrespectively) than in those with distal excursion (264 ± 56, 250± 48 ms respectively) or direct alignment (272 ± 61, 258± 73 ms respectively). Accessory pathways at the more posteriorlocation had a significantly higher incidence of proximal excursion (P= 0.006), and those at the more anterior location had a higherincidence of distal excursion (P = 0.012). In conclusion, a widevariation in fiber orientations and related electrophysiologic characteristics was found in left free-wall accessory pathways. This mayhave important clinical implications for radiofrequency ablation.     

Radiofrequency Ablation of Concealed Left Free-Wall Accessory Pathways Without Coronary Sinus Catheterization:

Ablation of Concealed Accessory Pathways. Introduction: Feasibility of radiofrequency (RF) ablation using a two-catheter technique without coronary sinus catheterization was studied in 100 consecutive patients with a single concealed left free-wall accessory path-way.
Methods and Results: Tachycardia was induced by electrical stimulation in the right atrium/right ventricle, and the presence of a concealed left free-wall accessory pathway was suggested electrocardiographically (negative P wave in leads I and/or a VL during orthodromic tachycardia) or by earlier atrial activation in the pulmonary artery compared to the high right atrium. Mapping of the mitral annulus was performed during right ventricular pacing or orthodromic tachycardia, and RF energy was applied at the site with the earliest retrograde atrial activation. Ablation was considered effective if tachycardia could not be induced, and if VA dissociation or exclusive retrograde nodal conduction was observed. Ablation was initially successful in 98 of 100 patients. Mean number of radiofrequency pulses were 3.2 ± 2. Mean fluoroscopy time and total procedure time was 14 ± 9 and 107 ± 32 minutes, respectively. There were no complications related to the procedure. At a mean follow-up of 22 ± 13 months, two patients experienced tachycardia recurrence and required a second procedure, which was successful.
Conclusions: Our results suggest that RF catheter ablation of concealed left free-wall accessory pathways can be safely, effectively, and rapidly performed using a simplified two-catheter technique with no need for coronary sinus catheterization.     

Radiofrequency Ablation of Atrial Insertion of Left-Sided Accessory Pathways Guided by the "W Sign"

AP Ablation and the "W Sign." introduction: The aim of this study was to evaluate the efficacy of radiofrequency (RF) ablation of the atrial insertion of left-sided aceessory pathways with guidance by a specific morphologic characteristic of the local electrogram, which we call the "W sign." This represents the shortest local atrioventricular (AV) interval during sinus rhythm in patients with manifest preexcitation or the shortest local VA interval during AV reciprocating tachycardia and/or ventricular pacing in patients with concealed accessory pathways.
Methods and Results: The transseptal technique was used in 31 patients (18 men, 13 women; aged 32 ± 13 years), and RF ablation of 33 accessory pathways (26 manifest and 7 concealed) was attempted. Patients presented with palpitations (n = 16), presyncope (n = 10), or syncope (n = 5). The clinical arrhythmia was AV reciprocating tachycardia (n = 24) or atrial fibrillation (n = 7). In 21 patients (68%) electrophysiologic study and RF ablation were performed at a single session. Accessory pathways were left posteroseptal (n = 5) or left free wall (n = 28). The "W sign," formed from merging of the local atrial and ventricular electrograms, was identified at all successful sites prior to ablation. Ablation was successful in all patients. A median of 7 RF lesions were delivered per patient. The fluoroscopy time was 76 ± 48 minutes; total procedure time was 5.4 ± 1.9 hours. No significant complications occurred. Early recurrence (≤ 24 hours) occurred in I patient; during 6 ± 4 months, accessory pathway conduction recurred in another patient.
Conclusion: We conclude that RF ablation of the atrial insertion of left accessory pathways can be very successful when guided by the "W sign."     

Accessory Pathway with Two Conduction Times

A 48-year old man was referred for frequent paroxysmal narrow QRS tachycardias. Either a rapid orthodromic tachycardia (220 b/min) using a fast-conducting left lateral concealed atrioventricular (AV) accessory pathway (AP) for its retrograde conduction or a slow orthodromic tachycardia (125 b/min) using the same concealed AP which was slow-conducting, were induced. One application of radiofrequency energy at the earliest site of retrograde conduction suppressed both forms of tachycardias. Reciprocating tachycardias presenting with different retrograde conduction times were related to a single reentrant circuit.     

经冠状静脉窦射频消融心外膜旁道

报道 13例左侧心外膜旁道的特点和经冠状静脉窦射频消融的结果。 13例左侧旁道患者先经心内膜标测和消融 ,如不成功改由经冠状静脉窦标测 ,记录到旁道电位或最早激动的V波或逆传A波即进行消融。结果 :13例患者全部成功 ,平均放电 1.5± 0 .6次 ,能量 2 1± 4W ,时间 2 1± 9s。成功消融靶点 :左侧游离壁 2例、左后间隔冠状静脉窦憩室 4例、心中静脉 7例。 11例有效靶点均标测到振幅较大的旁路电位 ,其振幅大于A波和V波 ,与二者之比均大于 1。结论 :冠状静脉窦标测到振幅较大的旁道电位是左侧心外膜旁道的重要标志 ;冠状静脉窦消融可以有效地阻断心外膜侧旁道     

Unusual Locations for Adenosine-Sensitive Accessory Atrioventricular Pathways with Decremental Conduction

Locations of Decremental Accessory Pathways. Introduction : Accessory AV pathways with decremental conduction are uncommon and, in particular, are thought not to occur at the anterior portion of the mitral annulus.
Methods and Results : This report describes successful catheter ablation in three patients with accessory AV pathways that were adenosine sensitive and showed decremental conduction properties. The pathways were located at the anteroseptal, anteroparaseptal, and anterolateral aspects of the mitral annulus.
Conclusion : Accessory pathways with decremental conduction do occur anywhere around the mitral annulus, even in the area of fibrous continuity between the aortic leaflet of the mitral valve and the aortic valve itself.     

穿间隔法与经主动脉逆行法消融左侧房室旁道的对比研究

按随机化原则对１２７例左侧房室旁道分别采用穿间隔（ＴＳ）法（６６例）和经主动脉逆行（ＴＡ）法（６１例）进行射频消融。ＴＳ法成功率１００％，ＴＡ法为９５％（５８／６１），两者相比无显著性差异。３例ＴＡ法失败者同次采用ＴＳ法消融成功。ＴＳ法和ＴＡ法消融操作时间依次为７６±２３和８１±２１ｍｉｎ、Ｘ线照射时间为１２±８和１３±７ｍｉｎ、放电次数为３±２和３±３次，各参数分别进行比较，均无显著性差异。随访９．１±４．９月，ＴＡ法消融有１例心动过速复发，经ＴＳ法再次消融成功。两组病人均无并发症发生。术者可根据个人对这两种方法掌握的熟练程度而选用     

经冠状静脉窦标测和消融后间隔心外膜房室旁道

报道心外膜房室旁道的特点和经冠状静脉窦射频消融术的结果。3例后间隔显性房室旁道患者先经心内膜标测和消融,不成功后改由经冠状静脉窦内标测和消融。术中冠状动脉造影,观察冠状静脉窦形态。结果: 2例冠状静脉窦近端有一憩室,并在憩室的颈部消融阻断房室旁道。成功靶点图为标测到振幅较大的旁道电位,其振幅大于A波和V波。结论:经心内膜标测和消融失败的旁道可能是心外膜旁道,行冠状静脉窦内标测与消融可有效阻断旁道,冠状静脉窦憩室与后间隔旁道可能存在着解剖关系。     

左室起搏标测消融左侧隐匿性旁道靶点的探讨

探讨左侧旁道 (AP)构成的房室折返性心动过速 (AVRT)的标测及射频消融 (RFCA)靶点定位方法。 15 4例左侧隐匿性AP构成的AVRT随机分成A、B两组 ,两组均经股动脉逆行法进入大头电极 (ABL)于二尖瓣环下RFCA。A组经大头电极以S1S135 0～ 5 0 0ms沿二尖瓣环起搏 ;以起搏信号S到CS上最早逆传A波之间的间距S -A最小处为靶点。B组以AVRT和 /或右室心尖部起搏时CS最早逆传A波处为靶点。结果 :A组 75例均经 1～ 2次放电即成功阻断AP ,且V、A分离均在放电后 5s内出现。其中有 9例靶点与CS上最早逆行A波处相距 10～ 15mm ,其靶点处S-A较其余 6 6例明显延长。B组 79例中 6 8例在 1～ 2次放电 ,5s内V、A分离 ,另 11例放电无效在改用A组方法后均在一次放电后即阻断AP ,靶点距CS最早逆A波处 10～ 2 0mm ,S -A显著长于该组其他病例。 15 4例中 2 0例靶点与CS上最早逆行A波有距离 ,其S -A明显延长 (5 6± 2 3msvs 4 5± 12ms,P <0 .0 1)。结论 :以最短S -A为靶点能快速有效地阻断各种类型的左侧隐匿性AP ;尤其在以最早逆行A波为靶点无法阻断AP传导时推荐使用该方法。     

Ablation of Left Free-Wall Accessory Pathways Using Radiofrequency Energy at the Atrial Insertion Site:

Transseptal versus Transaortic Ablation. Introduction: Transcatheter ablation of the left free-wall atrioventricular accessory pathways (AP) by delivery of radiofrequency current at the ventricular insertion site has been shown to be effective. The efficacy of such a technique targeting the atrial insertion site of the AP was evaluated.
Methods and Results: One hundred consecutive patients with left free-wall APs and symptomatic supraventricular tachyarrhythmias were included. APs were manifest in 55 patients and concealed in 45. There were 55 men and 45 women with a mean age of 35 years. A total of 107 left free-wall APs were identified in these patients. In these 100 patients, successful ablation was accomplished in all by using a transseptal (45 patients) or transaortic (54 patients) technique. In one patient, ablation was accomplished from within the coronary sinus. Seven patients required a repeat ablative procedure, which was performed successfully. During 107 ablative procedures, six were associated with nonfatal complications including pericardial effusion (hemopericardium) in two patients, mild mitral regurgitation in two patients, swelling of the left arm in one patient, and staphylococcal bacteremia in one patient. Eighty-two (82%) patients underwent a repeat electrophysiologic study 6 to 8 weeks after successful ablation and were found to have no functioning AP or inducible supraventricular tachycardia. During a mean follow-up of 20 ± 8 months, none of the 100 patients had a recurrence of tachyarrhythmias.
Conclusion: These data indicate that the atrial insertion site of the AP can be successfully ablated in the majority of patients with left free-wall APs by using cither a transseptal or transaortic approach. Furthermore, both techniques are associated with minimal morbidity and no mortality.     

Safety and Efficacy of Outpatient Transseptal Radiofrequency Ablation of Atrioventricular Accessory Pathways

A retrospective analysis of 60 consecutive patients who underwent outpatient transseptal radiofrequency ablation of left sided accessory pathways at Westchester County Medical Center/New York Medical College from September 1994 to December 1997 was performed. Patients were followed for a mean duration of 22 months. No complications either local or related to the transseptal method were observed. All patients had successful ablation of the accessory pathway. One patient had a recurrence of symptoms. This study suggests transseptal radiofrequency ablation of the left sided accessory pathways to be safe, feasible and an effective procedure when performed in an outpatient setting. These results were obtained at a high volume center with experience using the transseptal technique.     

Radiofrequency Catheter Ablation of Three Accessory Pathways in a Single Session

Radiofrequency Ablation of Multiple Accessory Pathways. A 19-year-old patient is described having three accessory atrioventricular pathways. All three pathways were ablated using radiofrequency current in a single electrophysiologic investigation. (J Cardiovasc Electrophysiol, Vol. 3, pp. 141–149, April 1992)     

预激综合征合并心房颤动与房室旁道位置分布的关系

为探讨预激综合征合并心房颤动（简称房颤）的临床特点和机制以及与房室旁道位置分布的关系，对经导管射频消融（连续治疗）成功的２９８例预激综合征患者进行了分析，其中２６例患者既往心电图证实有房颤发作。结果表明：显性旁道合并房颤（２２／１７４，１３％）多于隐匿性旁道（４／１２４，３％），Ｐ＜０．００５；右侧旁道（１７／１０５，１６％）多于左侧旁道（９／１９３，５％），Ｐ＜０．０５；右侧显性旁道（１６／９０，１８％）多于左侧显性旁道（６／８４，７％），Ｐ＜０．０１。即显性旁道尤其是右侧显性旁道合并房颤较多。支持显性旁道患者心室收缩提前（右侧旁道心室激动发生得更早）导致心房内压升高及电不稳定是预激综合征患者房颤发生机制的论点     

The Experience of Radiofrequency Ablation for Treatment of Multiple Accessory Pathways

Objective To analyse retrospectively the experience of radiofrequency ablation for successful treatment of multiple accessory pathways (APS). Methods 150 patients with supraventricu-lar tachycardia related to APS have undergone radiofrequency ablation since 1994; the data was analysed. Results 8 patients with multiple APS were cured, 4 patients could be diagnosed to have multiple APS during electrophysiologic study (EPS) before ablation, and in the remaining 4 patients the multiple APS could only be diagnosed after successful ablation of one AP. Conclusion right - sided multiple APS are sometimes very difficult to treat by ablation, because there are no standard reference electrograms for bracketing the earliest site. Mapping area should be broader rather than limited by preestablished idea.     

Unexpected Emergence of Manifest Preexcitation Following Transcatheter Ablation of Concealed Accessory Pathways

Preexcitation After Catheter Ablation. Introduction: The basis for anterograde or retrograde unidirectional block of accessory pathways still remains a controversial issue.
Methods and Results: Four of 19 consecutive patients (1 mule, 3 Female; ages 27 to 34 years) who underwent transcatheter ablation of concealed accessory pathways developed manifest preexcitation after the ablation. The location of the concealed accessory pathways in these four patients were right lateral, left posteroseptal, left posterolateral, and left lateral. Radiofrequency current was used in three of the four patients and high energy direct current in one patient. After ablation, manifest preexcitation was observed in these four patients for the first time. Manifest preexcitation developed immediately after ablation in two of the four patients and after 4 and 14 days in the other two. Detailed endocardial mapping revealed that the manifest preexcitation originated from the same location as the concealed pathways. Subsequently, catheter ablation was successfully performed in three of the four patients using radiofrequency current. One patient underwent successful surgical ablation. No recurrence of preexcitation was observed during a follow-up period of 9 to 38 months. All patients remained free of arrhythmias.
Conclusion: The basis for this unexpected emergence of preexcitation in these patients with only retrograde conducting accessory pathways deserves further investigation. Although not compared in the present study, this phenomenon has not been reported in patients who underwent surgical interruption of accessory pathways. We postulate that a lesion at the site of insertion of the accessory pathway had modified the anterograde conduction capacity.     

Accuracy and Limitations of Published Algorithms Using the Twelve-Lead Electrocardiogram to Localize Overt Atrioventricular Accessory Pathways

INTRODUCTION: The purpose of this study was to evaluate the accuracy and limitations of published algorithms using the 12-lead ECG to localize AV accessory pathways (APs). METHODS AND RESULTS: The 11 relevant algorithms found in the literature (MEDLINE database and major scientific sessions) were tested on a series of 266 consecutive patients who successfully underwent radiofrequency catheter ablation of a single overt AV AP. The positive predictive values (PPV) of the algorithms in applicable patients were significantly lower for algorithms with > 6 accessory location sites (40.6% +/- 10.9% vs 61.2% +/- 8.0%; P < 0.03) and show a tendency for algorithms not relying on delta wave polarity but on QRS polarity only (36.6% +/- 11.2% vs 52.3% +/- 13.1%; P = 0.09). The PPV in applicable patients is related to the AP location (P < 0.001) and ranked from the highest to the lowest as follows: left lateral (mean PPV = 86.3%), posteroseptal (mean PPV = 65.2%), right anteroseptal (mean PPV = 45.2%), and right posterolateral (mean PPV = 23.4%). CONCLUSION: Our study suggests that the accuracy of algorithms relying on the 12-lead ECG depends on AP locations as defined in the algorithms and on the number of AP sites. The accuracy tends to be lower when delta wave polarity is not included in the algorithm's architecture. This should be considered when using these algorithms or when building new ones.     

Electrophysiologic Characteristics and Anatomical Complexities of Accessory Atrioventricular Pathways with Successful Ablation of Anterograde and Retrograde Conduction at Different Sites

RF Ablation of Accessory Pathways. Introduction: Catheter ablation may eliminate anterograde and retrograde accessory pathway conduction at closely adjacent but anatomically discrete sites. However, the mechanisms of this discrepancy, the electrophysiologic and anatomical characteristics, and information about systematic study from a large patient population are not available. The purpose of this study was to investigate the electrophysiologic characteristics and anatomical complexities of the accessory pathway in which anterograde and retrograde conduction was successfully ablated at different sites. Methods and Results: Thirty-eight (10.9%) patients (19 men and 19 women; mean age 37 ± 2.4 years) fulfilling the criteria of having separate ablation sites for anterograde and retrograde conduction were designated as group I, and the other 310 patients (215 men and 95 women; mean age 47 ± 0.6 years) were designated as group II. The patients with right-sided free-wall pathways had the highest incidence (18.6%) of separate ablation sites. The anatomical distance between anterograde and retrograde directions (left anterior oblique view. 13 ± 0.6 vs 8 ± 0.9 mm, P < 0.01; right anterior oblique view, 17 ± 0.6 vs 5 ± 0.7 mm, P < 0.01), and incidence of conduction impairment in one direction after successful ablation of another direction (15% vs 78%, P < 0.05) differed significantly between left and right free-wall pathways. The mean distances obtained from left (7 ±0.4 vs 14 ± 0.4 mm, P < 0.05) and right (7 ± 1.1 vs 15 ± 0.9 mm, P < 0.05) anterior oblique views were shorter in patients who had impairment of conduction properties than those in patients without impaired conduction after successful ablation of one direction. Conclusions: This study showed that anatomical and functional dissociation of the accessory pathway into anterograde and retrograde components was possible. Further study on the relation between electropbysiologic and pathologic characteristics would be helpful to confirm these findings.     

心脏冷冻和射频消融的组织病理学研究

射频消融和冷凝消融在心律失常方面的应用已经有了突破性的进展，尤其是对某些快速性心律失常已成为根治性治疗手段。现综述旨在阐明射频和冷凝消融在组织病理学方面的研究进展，从而克服常规消融的一些缺陷。