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 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.     

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     

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.     

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。     

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)     

Radiofrequency Catheter Ablation of Two Right Mahaïm-like Accessory Pathways in a Patient with Ebstein's Anomaly

A 17-year-old woman with Ebstein's anomaly and recurrent episodes of antidromic tachycardia with two distinct morphologies is described. The tachycardias were produced by two separate Mahaïm-like accessory pathways. These were localized by their activation potentials at the anterolateral ventricular margin of the tricuspid annulus and ablated in a single session using radiofrequency current.     

Multiple Concealed Accessory Pathways Associate with Antegrade Triple AV Nodal Pathways and Catheter Ablation

This article describes a 54-year-old man with incessant supraven-tricular tachycardia refractory to antiarrhythmic drugs. Multiple concealed accessory pathways associated with antegrade triple AV nodal pathways were documented by a series of successful catheter ablations and detailed electrophysiological studies. After the left-wall accessory pathways were abolished with two courses of multiple low energy shocks, another two accessory pathways, one near the os of coronary sinus and the other near the site of the His bundle, were documented by programmed premature ventricular stimulation. This was followed by a third course of shocks to the os of coronary sinus for ablating posteroseptal AP and a fourth course of shock to proximal His bundle for control of SVT with a septal accessory pathway as a retrograde limb and AV nodal pathways as an antegrade limb. Without medications, the patient has remained asymptomatic even during moderate physical activity over a follow-up period of 36 months. His ECG showed sinus rhythm with persistence of right bundle branch block.     

Inappropriate Sinus Tachycardia After Radiofrequency Ablation of Para-Hisian Accessory Pathways

Inappropriate Sinus Tachycardia After Catheter Ablation. Introduction : Inappropriate sinus tachycardia (IST) has been observed following radiofrequency ablation (RFA) of the AV nodal fast pathway. This study was aimed to prospectively analyze the incidence and clinical significance of IST following RFA of para-Hisian accessory pathways (APs).
Methods and Results : Twenty-eight patients (pts) with para-Hisian APs underwent RFA. An AP was defined as para-Hisian whenever its atrial and ventricular insertions were associated with a His-bundle potential ≥ 0.1 mV. RF current was always delivered at the atrial aspect of the tricuspid annulus. to a site where the His-bundle potential was < 0.15 mV. Time- and frequency-domain analysis of heart rate variability was performed in 22 patients, before and after RFA. Abolition of AP conduction was obtained in all pts, and no AV conduction alteration occurred. Six pts (21.4%) presented with IST 45 to 240 minutes after the ablation procedure. In 5 of them, IST disappeared spontaneously within 72 hours, whereas in 1 pt β-blockers were required for 2 months. The atrial potential amplitude (1.217 ± 0.264 mV vs 0.882 ± 0.173 mV, P = 0.009) and A/V potential amplitude ratio (2.633 vs 1.686, P = 0.05) were significantly higher in pts who developed IST than in those who did not. A marked decrease in heart rate variability was observed only in pts who developed IST.
Conclusion : IST is a relatively frequent complication after RFA of para-Hisian APs: it is generally short-lasting and usually does not require any treatment. IST after catheter ablation is likely to depend upon transient parasympathetic denervation of the sinus node.     

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.     

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.     

Radiofrequency Application to the Posteroseptal Region Alters Retrograde Accessory Pathway Activation

Introduction: Radiofrequency applications to the posteroseptal region can ablate the atrioventricular accessory pathway residing in this area. In conjunction with the adjacent anatomic structures, however, ablative lesions which do not effectively ablate the accessory pathway could markedly alter retrograde atrial activation sequence and confound interpretation of further mapping of an accessory pathway.Methods and Results: Electrophysiologic studies, endocardial activation mapping and radiofrequency catheter ablation were undertaken in three patients with recurrent supraventricular tachycardia. Patients were initially thought to have a single posteroseptal accessory pathway; earliest ventrioatrial activation during tachycardias and during ventricular pacing was at the coronary sinus ostium, but initial radiofrequency applications were unsuccessful to ablate the pathway. After initial radiofrequency applications to the posteroseptal region, the earliest retrograde atrial activation changed to the right atrial free wall in two patients. Additional radiofrequency application to the posteroseptal area was able to ablate the single posteroseptal accessory pathway in one patient. Radiofrequency application to the right atrial free wall was required to stop tachycardia initiation in other patient. The third patient was suspected of having a slow-slow atrioventricular nodal reentry tachycardia. Radiofrequency application to the posteroseptal area changed the earliest retrograde atrial activation to the distal coronary sinus recording site, mimicking an accessory pathway at the left atrial free wall. Radiofrequency application to the anteroseptum was able to ablate the concealed accessory pathway.Conclusion: Radiofrequency applications to the posteroseptal region can markedly alter retrograde atrial activation, thereby confounding further mapping of the accessory pathway.     

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。     

冠状静脉内导管射频消融治疗后间隔心外膜房室旁道的临床研究(附17例报告)

对 17例后间隔旁道的体表心电图特征、电生理特性及导管射频消融术方法学进行分析和探讨。男 11例、女6例 ,年龄 41± 2 4(11～ 73)岁。与后间隔心内膜旁道相比 ,后间隔心外膜旁道的体表心电图有其自身的特点。 17例患者 ,射频消融成功 16例 ,成功率 94%。 7例在冠状静脉窦内消融成功 ,8例在心中静脉内消融成功 ,1例在冠状静脉窦巨大憩室颈部消融成功 ,1例未成功。 17例手术时间 140± 87(86～ 180 )min ,X线曝光时间 42± 2 9(30～ 6 6 )min。 16例随访 1～ 2 4个月 ,无一例心动过速复发。结论 :在冠状静脉内消融成功的后间隔旁道具有一些特定的体表心电图特征。常规在左右侧间隔部标测无满意靶点且试放电无效时 ,应考虑为后间隔心外膜旁道 ,在冠状静脉内标测消融具有较高的成功率 ,能明显缩短手术时间和X线曝光时间 ,无并发症。     

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     

射频消融治疗预激综合征失败病例分析

以射频消融３０７例预激综合征患者，２４例未成功，前、中、后各百例内失败者各占１４，６和４例，成功率分别为８６％、９４％和９６．４％（１０３／１０７）．９例行二次消融成功。初期消融失败的主要原因为导管操作不熟练和旁路定位不精细。中、后期则主要原因为未准确识别某些特殊部位如后间隔及右游离壁旁路的局部电图特征。表明操作者的经验与成功率密切相关。     

Decremental Accessory Pathway Conduction After Ablation and Antidromic Atrioventricular Reciprocating Tachycardia 8 Years After Successful Radiofrequency Ablation

Introduction: This is a rare case of antidromic reciprocating tachycardia developing 8 years after successful catheter ablation.
Result: A 15-year-old girl had recurrence of palpitations 8 years after the ablation of manifest right posteroseptal accessory pathway. Atrial burst pacing revealed Wenckebach atrioventricular conduction with preexcitation. Wide QRS tachycardia with identical morphology to sinus rhythm associated with retrograde His potential recorded immediately after the V-wave was induced by isoproterenol infusion. Atrial premature stimulus applied at the identical timing of His potential advanced the subsequent ventricular beat and His potential.
Conclusion: Catheter ablation may produce decremental accessory pathway conduction and rarely cause antidromic atrioventricular reciprocating tachycardia. This may be explained by a presence of "de novo" accessory pathway with decremental conduction properties that became manifest after the first ablation.