Usefulness of predischarge electrophysiologic study in predicting late outcome after surgical ablation of the accessory pathway in the Wolff-Parkinson-White syndrome.

A predischarge electrophysiologic study was performed in 113 patients with the Wolff-Parkinson-White (WPW) syndrome who had undergone surgical ablation of the accessory pathway. The study was performed 5 to 20 (mean 10 +/- 3) days after surgery. There were 82 male and 31 female patients (aged 4 to 58 years, mean 36 +/- 13). Sixty-one patients (54%) had manifest, 52 (46%) had concealed and 12 (11%) had multiple accessory pathways. All but 1 patient had atrioventricular reentrant tachycardia incorporating single or multiple accessory pathways during the control electrophysiologic study. The accessory pathways were located in the left ventricular free wall in 60% of cases, right ventricular free wall in 22%, posteroseptum in 13%, and anteroseptum in 5%. The predischarge electrophysiologic study showed that the accessory pathway was capable of anterograde and retrograde conductions in 4 patients (all with manifest WPW syndrome). Four patients showed induction of supraventricular tachycardia, including 2 with atrioventricular reentrant tachycardia, and 2 with atrioventricular nodal reentrant tachycardia. Recurrence of supraventricular tachycardia was noted in 5 patients during a follow-up of 28 +/- 26 months. Of these 5 patients, 2 had inducible and 3 had no inducible supraventricular tachycardia during the predischarge electrophysiologic study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Surgery for Wolff-Parkinson-White syndrome: further experience with an epicardial approach

We have previously reported the use of an epicardial approach for ablation of left ventricular free wall accessory atrioventricular pathways. The technique involves mobilization of the atrioventricular fat pad and exposure and cryoablation of the atrioventricular junction at the site of the accessory pathway on the normothermic beating heart. Here we describe our further experience with left ventricular free wall accessory pathways and right ventricular free wall accessory pathways. Our experience is based on 53 consecutive patients. There were 35 male and 18 female subjects, 6 to 52 (mean 41.4) years old. Forty-eight patients had a left ventricular free wall accessory pathway, and five had a right ventricular free wall accessory pathway. Two patients had an associated anterior septal accessory pathway. Five patients had associated cardiac abnormalities, including atrial septal defect, aortic insufficiency, mitral valve prolapse, Ebstein's anomaly, and cardiomyopathy. The accessory pathway was ablated in 52 patients who remain arrhythmia free without medication after a mean follow-up period of 12 months. The accessory pathway was permanently modified in one patient. There were no postoperative complications. This epicardial approach can be performed with normothermic cardiopulmonary bypass or without bypass. It does not require cross-clamping of the aorta, allowing a greater margin of safety when this is required for concomitant procedures.     

应用磁导航技术遥控标测和消融治疗快速性心律失常

目的在数种快速性心律失常中,观察应用磁导航技术行遥控标测和消融治疗的可行性与安全性。方法对复杂程度不同的心律失常患者,采用NiobeII磁导航系统(Stereotaxis,Inc)遥控操作,用HeliosII磁性标测和消融导管行射频温控消融治疗。结果12例入选,男8例,女4例,年龄36.83±13.05岁。4例有晕厥,1例有心脏骤停,5例有器质性心脏病。房室结折返性心动过速3例,左前游离壁房室旁道3例,右游离壁房室旁道1例,左后间隔房室旁道伴心房颤动1例,左中间隔房室旁道伴房室结折返性心动过速1例,心房扑动1例,房性早搏/心房颤动1例,室性早搏/心室颤动1例。采用遥控操作,12例均完成电生理检查,11例可准确到达靶点部位,行射频消融,10例成功。操作时间149.17±68.95min,未见并发症。结论对复杂程度不同的心律失常,不管患者有无器质性心脏病,采用磁导航技术均可安全与可靠地实施遥控标测和消融治疗。     

Radiofrequency catheter ablation of both atrial ventricular nodal reentrant and atrial ventricular reentrant tachycardia in a single session

Radiofrequency catheter ablation is a new therapeutic approach to treat patients with symptomatic drug-resistant paroxysmal supraventricular tachycardia. Ablation of two accessory atrioventricular pathways in a single session has been frequently described previously. However, ablation in a single session of both the fast pathway, involved in atrial ventricular nodal reentrant tachycardia, and a concealed atrioventricular accessory pathway involved in a circus movement tachycardia has rarely been reported. A 57-year-old man with a grade III aortic incompetence had the infrequent association of atrial ventricular nodal reentrant tachycardia and orthodromic circus movement tachycardia due to a concealed accessory pathway. He presented with drug-resistant reentrant supraventricular tachycardia and, in a single session, underwent a successful radiofrequency catheter ablation of the fast atrial ventricular nodal pathway and a concealed posteroseptal accessory pathway. During a 10-month follow-up he was free of palpitations without any antiarrhythmic therapy and underwent elective aortic valve replacement.     

Curative percutaneous catheter ablation using radiofrequency energy for accessory pathways in all locations: results in 100 consecutive patients.

Patients with accessory pathway-mediated supraventricular tachycardia have typically been treated with drugs or surgery. Although catheter ablation using high voltage direct current shocks has been used to treat patients with drug-refractory supraventricular tachycardia, there are associated disadvantages, including damage due to barotrauma as well as the need for general anesthesia. Recently, transcatheter radiofrequency energy has evolved as an alternative to direct current shock or surgery to ablate accessory pathways. Percutaneous catheter ablation of 109 accessory pathways with use of radiofrequency energy was attempted in 100 consecutive patients. Patient age ranged from 3 to 67 years. The patients had been treated for recurrent tachycardia with a mean of 2.7 +/- 0.2 antiarrhythmic agents that either proved ineffective or caused unacceptable side effects. In seven patients previous attempts at accessory pathway ablation with use of direct current shock had been unsuccessful. Forty-five (41%) of the pathways were left free wall, 43 (40%) were septal and 21 (19%) were right free wall. Eighty-nine (89%) of the 100 patients had successful radiofrequency ablation at the time of hospital discharge. In all but 12 patients the ablation was accomplished in a single session. Complications attributable to the procedure, but not to the ablation itself, occurred in four patients (4%). No patient developed atrioventricular block or other cardiac arrhythmias. Over a mean follow-up period of 10 months, nine patients had some return of accessory pathway conduction; a repeat ablation procedure was successful in all five patients in whom it was attempted. It is concluded that a catheter ablation procedure using radiofrequency energy can be performed on accessory pathways in all locations. The procedure is effective and safer, less costly and more convenient than cardiac surgery and can be considered as an alternative to lifelong medical therapy in any patient with symptomatic accessory pathway-mediated tachycardia.     

Radiofrequency catheter ablation of accessory atrioventricular pathways in children and young adults.

OBJECTIVE--To assess the efficacy of radiofrequency ablation for reentrant tachyarrhythmias in children and young adults. SETTING--A tertiary cardiac referral centre. PATIENTS AND INTERVENTIONS--Over a 16 month period 22 patients aged less than 20 years (median age 16.5 years) underwent 26 radiofrequency ablation procedures for atrioventricular reentry tachycardia through an accessory pathway. The results of radiofrequency ablation were compared with those in a group of 16 patients (median age 14 years) who had had surgical ablation for atrioventricular reentry tachycardia over a preceding six year period. RESULTS--Ablation of an accessory atrioventricular pathway was accomplished for 18 (76%) of 25 pathways in 16 (73%) of 22 patients. There were no procedure-related complications. Surgery was eventually curative in 15/16 patients (94%). However, three patients required a second open heart surgical procedure because tachyarrhythmia recurred. There were no surgical deaths. Failures for radiofrequency ablation were related to accessory pathway location, and were greater for right free wall and posteroseptal pathways (success rate of 50% and 57% respectively). Recurrence after surgery was also associated with pathways in these locations. CONCLUSIONS--Transcatheter radiofrequency current ablation was safe and achieved a cure with less patient morbidity and improved cost efficiency. It is an attractive alternative to long-term drug therapy or surgery in older children and adolescents. A higher success rate may be expected with increased experience.     

Radiofrequency catheter ablation of Mahaim tachycardia by targeting Mahaim potentials at the tricuspid annulus.

BACKGROUND--Reentrant tachycardias associated with Mahaim pathways are rare but potentially troublesome. Various electrophysiological substrates have been postulated and catheter ablation at several sites has been described. OBJECTIVE--To assess the efficacy and feasibility of targeting discrete Mahaim potentials recorded on the tricuspid annulus for the delivery of radiofrequency energy in the treatment of Mahaim tachycardia. PATIENTS--21 patients out of a consecutive series of 579 patients referred to one of three tertiary centres for catheter ablation of accessory pathways causing tachycardia. All had symptoms and presented with tachycardia of left bundle branch block configuration or had this induced at electrophysiological study. In all cases, the tachycardia was antidromic with anterograde conduction over a Mahaim pathway. RESULTS--6 patients had additional tachycardia substrates (4 had accessory atrioventricular connections and 2 had dual atrioventricular nodal pathways and atrioventricular nodal reentry). After ablation of the additional pathways, Mahaim potentials were identified in 16 (76%) associated with early activation of the distal right bundle branch and radiofrequency energy at this site on the tricuspid annulus abolished Mahaim conduction in all 16 cases. In 2 patients there was early ventricular activation at the annulus without a Mahaim potential but radiofrequency energy abolished pre-excitation. In the remaining patients no potential could be found (1 patient), no tachycardia could be induced after ablation of an additional pathway (1 patient), or no Mahaim conduction was evident during the study (1 patient). During follow up (1-29 months (median 9 months)) all but 1 patient remained symptom free without medication. CONCLUSIONS--Additional accessory pathways seem to be common in patients with Mahaim tachycardias. The identification of Mahaim potentials at the tricuspid annulus confirms that most of these pathways are in the right free wall and permits their successful ablation and the abolition of associated tachycardia.     

29例房束型和短房室型Mahaim纤维的电生理特点与射频消融结果

目的报道29例房束型和短房室型Mahaim纤维的电生理特点与射频消融结果。方法对29例Mahaim纤维患者（房束型10例,短房室型19例）进行心内电生理检查和射频导管消融治疗。结果29例患者Mahaim纤维只存在递减性前向传导功能,其中2例合并隐匿性房室旁路（左侧游离壁和右侧中间隔各1例）,2例合并三尖瓣峡部依赖型心房扑动,3例合并房室结双径路（均为慢快型）。经Mahaim纤维前传的逆向性房室折返性心动过速时,房束型心室最早激动点在右心室心尖部,短房室型心室最早激动点在三尖瓣环消融靶点处。于三尖瓣环的心房侧成功消融所有Mahaim纤维,其中28例于三尖瓣环游离壁的心房侧消融成功,1例于右心房中间隔消融成功。13例标测到明显的Mahaim纤维电位,25例（房束型9例,短房室型16例）有效消融时出现加速性Mahaim纤维的自主心律。合并房室结双径路、隐匿性房室旁路和三尖瓣峡部依赖型心房扑动者,分别给予以慢径改良、旁路消融和右心房峡部线性消融。随访（17＋8）个月,无1例心动过速复发。结论Mahaim纤维多位于三尖瓣环游离壁。导管消融是Mahaim纤维介导的心动过速安全、有效的治疗方法。消融中出现加速性Mahaim纤维自主心律可以作为判定有效消融的预测指标。消融术前和术后应进行详尽的电生理检查以明确是否合并其他的心动过速。     

室性心动过速合并室上性心动过速的射频消融

目的报道7例室性心动过速（VT）合并室上性心动过速（sVT）的射频消融。方法7例患者男6例,女1例,平均年龄（21±9）岁。阵发性心动过速病史（3．7±2．0）年。术中心房和心室刺激诱发VT和SVT,并进行消融。结果7例患者心房或心室刺激能反复诱发和终止VT合并SVT。法洛四联症矫治术后右心室VT合并三尖瓣环峡部依赖性心房扑动（AFL）1例,其余6例均为维拉帕米敏感性左心室特发性室速（ILVT）,分别合并AFL1例,左后间隔旁路参与的顺向型房室折返性心动过速（AVRT）1例,冠状静脉窦口慢旁路参与的顺向型AVRT1例,慢慢型房室结折返性心动过速（AVNRT）1例,左侧游离壁旁路参与的顺向型AVRT2例。7例患者的两种心动过速均成功消融,所有患者消融术后随访2年,无一例VT或SVT复发。结论VT合并SVT并不少见,消融术中应放置必需的心腔内电极导管,完成详细电生理检查,避免漏诊。一次消融应根除两种疾病。     

Mechanisms of junctional tachycardia showing ventricular pre-excitation.

Over a period of five years 12 patients underwent electrophysiological studies for the investigation of recurrent tachycardias which showed ventricular pre-excitation. Nine patients had a type B pattern and two a type A. One patient had episodes of both types. Dual atrioventricular nodal pathways were found in six of seven patients with atrioventricular nodal re-entrant tachycardia mechanisms. Single direct atrioventricular accessory pathways were present in four patients, single nodoventricular pathways in five, and multiple pathways in three. Twenty one tachycardias were induced, of which 13 showed ventricular pre-excitation. Five patients had nodoventricular pathway conduction during atrioventricular nodal tachycardia and one during atrioventricular re-entrant tachycardia. Only three patients had simple antidromic tachycardia and one additional atrioventricular nodal tachycardia with bystander atrioventricular accessory conduction. Three patients had three different tachycardias, three had two types, and six had one type. Thus junctional tachycardias showing ventricular pre-excitation are often associated with multiple mechanisms and complex anatomical and functional substrates. An accessory pathway was an essential component in only six of 13 tachycardias showing ventricular pre-excitation. Determination of the tachycardia mechanism requires detailed study and analysis.     

Mechanisms of junctional tachycardia showing ventricular pre-excitation

Over a period of five years 12 patients underwent electrophysiological studies for the investigation of recurrent tachycardias which showed ventricular pre-excitation. Nine patients had a type B pattern and two a type A. One patient had episodes of both types. Dual atrioventricular nodal pathways were found in six of seven patients with atrioventricular nodal re-entrant tachycardia mechanisms. Single direct atrioventricular accessory pathways were present in four patients, single nodoventricular pathways in five, and multiple pathways in three. Twenty one tachycardias were induced, of which 13 showed ventricular pre-excitation. Five patients had nodoventricular pathway conduction during atrioventricular nodal tachycardia and one during atrioventricular re-entrant tachycardia. Only three patients had simple antidromic tachycardia and one additional atrioventricular nodal tachycardia with bystander atrioventricular accessory conduction. Three patients had three different tachycardias, three had two types, and six had one type. Thus junctional tachycardias showing ventricular pre-excitation are often associated with multiple mechanisms and complex anatomical and functional substrates. An accessory pathway was an essential component in only six of 13 tachycardias showing ventricular pre-excitation. Determination of the tachycardia mechanism requires detailed study and analysis.     

Cryoablation of the accessory pathway in Wolff-Parkinson-White syndrome: initial results and long term follow up.

Cryoablation of the accessory pathway was used in the management of 20 patients with pre-excitation syndromes. All patients had presented with paroxysmal atrioventricular reentrant tachycardia; in addition, six had experienced atrial fibrillation. In 16 patients pre-excitation was overt and in four the accessory pathway was concealed. Intraoperative epicardial and endocardial mapping showed 10 left free wall pathways, seven septal pathways, and four right free wall pathways. One patient had two right free wall accessory pathways. There was one postoperative death (from a ruptured cerebral haemangioma) and one patient had transient hemiparesis. There was early recurrence of arrhythmia or pre-excitation in six patients and five of these were among the first ten in the series. Four of the six underwent successful reoperation; 17 patients remain symptom free of all antiarrhythmic treatment. Two patients did not undergo reoperation--one became symptom free on drugs that had previously been ineffective and the other received an antitachycardia pacemaker. The mean period of follow up was six years. Accessory pathway function was not restored and atrioventricular nodal function was preserved in all patients, demonstrating the feasibility of this technique in the long term management of patients with the pre-excitation syndrome.     

Cryoablation of the accessory pathway in Wolff-Parkinson-White syndrome: initial results and long term follow up

Cryoablation of the accessory pathway was used in the management of 20 patients with pre-excitation syndromes. All patients had presented with paroxysmal atrioventricular reentrant tachycardia; in addition, six had experienced atrial fibrillation. In 16 patients pre-excitation was overt and in four the accessory pathway was concealed. Intraoperative epicardial and endocardial mapping showed 10 left free wall pathways, seven septal pathways, and four right free wall pathways. One patient had two right free wall accessory pathways. There was one postoperative death (from a ruptured cerebral haemangioma) and one patient had transient hemiparesis. There was early recurrence of arrhythmia or pre-excitation in six patients and five of these were among the first ten in the series. Four of the six underwent successful reoperation; 17 patients remain symptom free of all antiarrhythmic treatment. Two patients did not undergo reoperation--one became symptom free on drugs that had previously been ineffective and the other received an antitachycardia pacemaker. The mean period of follow up was six years. Accessory pathway function was not restored and atrioventricular nodal function was preserved in all patients, demonstrating the feasibility of this technique in the long term management of patients with the pre-excitation syndrome.     

Heart Rate Variability: Does it Change After RF Ablation of Reentrant Supraventricular Tachycardia?

Background: Following RF ablation of reentrant supraventricular tachycardia, inappropriate sinus tachycardia may occur. Local parasympathetic denervation is a possible mechanism for these rhythm disturbances. The purpose of this study was to determine the incidence of sinus tachycardia and to determine the relation between endocardial lesions at different ablation sites and alterations in autonomic tone in several different groups of patients with supraventricular tachycardia, using techniques of heart rate variability analysis. Methods: The subjects of this study were 75 patients (48 women, 27 men) with a mean age of 39.99 (SD = 13.39). They underwent RF ablation of AV nodal slow pathways (40 cases), posteroseptal APs (23 cases), left lateral and right free wall APs (12 cases) because of symptomatic tachycardias. The mean sinus rate and time domain (standard deviation of RR intervals and root mean square of differences of adjacent RR intervals) and frequency domain (low frequency, high frequency and low frequency/high frequency ratio) analyses of heart rate variability were obtained by use of 24 hour Holter monitoring before and 1 month after ablation compared with pre-ablation values. Results: Analysis of 24 hour ambulatory Holter-monitors, performed 1 month after RF ablation, showed no significant changes in time and frequency domain parameters of heart rate variability in different groups. A significant increase in mean heart rate was noted after RF ablation at AV nodal slow pathway group and left freewall/right free wall accessory pathways group. Patients undergoing RF ablation of right or left posteroseptal accessory pathways had no significant increase in the mean heart rate. Conclusion: In summary, an increase in sinus tachycardia may be initiated by RF ablation of atrioventricular reentrant tachycardia (AVNRT) and right free wall or left free wall accessory pathways. This finding shows that the modifications of heart rate are not directly related to the posteroseptal region or to the accessory pathways.     

Mahaim纤维的电生理特征和导管射频消融

探讨Mahaim纤维的电生理特征和导管射频消融的可行性。 1996年 5月至 1999年 4月对 4例拟诊为Mahaim纤维引起的逆向型房室折返性心动过速的病人进行了电生理检查和射频导管消融。男 3例、女 1例 ,年龄 31± 19岁 ,心动过速发作史 15± 14年 ,频率 2 0 1± 17(180～ 2 2 0 )次 /分 ,发作时均有明显的心悸症状。 4例窦性心律时心电图除 1例轻微预激外均正常。心房程序电刺激可以诱发心动过速。心室起搏时从房室结逆传 ,静脉注射ATP 2 0mg室房分离。 4例Mahaim心动过速均只有前传并呈递减传导特性。 1例同时合并房室结折返性心动过速。 2例导管操作发生心房颤动并经过Mahaim纤维前传 ,1例持续发作、1例短暂发作。 4例分别在心房起搏、心动过速和心房颤动时三尖瓣心房侧标测和消融。心室预激较体表V1导联QRS波起始处提前 40± 6 (34～ 46 )ms处消融均获成功 ,1例靶点位于右前侧壁、3例位于右后侧壁。能量 35± 5W ,消融 5± 3次 ,X线透视时间 38± 2 1min。无手术相关的并发症。合并房室结折返性心动过速 1例同时作了慢径改良。分别随访 3个月～ 3年无 1例心动过速复发。临床研究证实 ,导管射频消融是治疗Mahaim介导的心动过速的有效、可行和安全的方法     

Catheter ablation of accessory pathways with a direct approach. Results in 35 patients

Thirty-five consecutive patients with an overt accessory pathway, all but two suffering from arrhythmia (atrial fibrillation, reciprocating tachycardia, or both), underwent attempted transcatheter ablation (fulguration) of their accessory pathway. Thirty-three patients had been treated with a mean of 2.3 +/- 1.4 antiarrhythmic drugs. A standard bipolar catheter was positioned on the internal surface of the right or left atrioventricular anulus with 1) a subclavian approach of the right cardiac cavities in 29 patients with right-sided accessory pathway (n = 27) or left posteroseptal accessory pathway (n = 2), 2) a patent foramen ovale in five patients (two with a left posterolateral accessory pathway and three with a left parietal accessory pathway), and a transseptal catheterism (one patient with a left parietal accessory pathway). Cathodic shocks (mean, 4.3 shocks/patient) with a mean cumulative energy of 690 J enabled the ablation (disappearance of both anterograde and retrograde conduction) of the accessory pathway in 32 patients with a follow-up ranging from 1 to 32 months (mean, 10 +/- 8 months). Two of the remaining three accessory pathways were impaired: one pathway became intermittent, the anterograde effective refractory period of the second pathway increased from 260 to 410 msec, and the third pathway was slightly impaired. This latter patient is the only one who still requires therapy, with a single antiarrhythmic drug. All others are free of arrhythmias and require no therapy. Not using coronary sinus catheterism inclusive of its os has led to only a few, benign side effects. Only one third-degree atrioventricular block occurred in a posteroseptal accessory pathway ablation. Three cases of patients with incessant reciprocating tachycardia involving a further successful ablation occurred at the beginning of our experience. The best area for ablation is, in our opinion, the recording site for the Kent-bundle activity (18 of 35 patients), but a meticulous mapping of the atrioventricular anulus during orthodromic reciprocating tachycardia makes ablation possible when the shortest ventriculoatrial time (V-A') can be recorded with reliability (mean, 85 +/- 18 msec). Such a procedure is an alternative to surgical ablation regardless of the location of the accessory pathway--not only posteroseptally.     

Radiofrequency catheter ablation of accessory pathways in infants.

OBJECTIVE: To evaluate the indications, results and complications of radiofrequency catheter ablation in small infants with supraventricular tachycardia due to an accessory atrioventricular pathway. METHODS: Five infants less than 9 months old underwent radiofrequency catheter ablation of accessory pathways. Ablation was done for medically refractory tachyarrhythmia associated with aborted sudden death in two patients, left ventricular dysfunction in one, failure of antiarrhythmic drugs in one, and planned cardiac surgery in one. All five patients underwent a single successful procedure. Three left free wall pathways were ablated by transseptal approach, a right posteroseptal pathway was ablated from the inferior vena cava, and a left posteroseptal pathway was approached from the inferior vena cava into the coronary sinus. A deflectable 5F bipolar electrode catheter with a 3 mm tip was used. RESULTS: A sudden increment in impedance indicative of coagulum formation was observed in two procedures. One patient developed a transient ischaemic complication after ablation of a left lateral accessory pathway by transseptal approach. This patient had mild pericardial effusion after the procedure. Moderate pericardial effusion was also noted in another patient. After a mean follow up of 18.4 months all patients are symptom free without treatment. CONCLUSIONS: Radiofrequency catheter ablation can be performed successfully in infants. Temperature monitoring in 5F ablation catheters would be desirable to prevent the development of coagulum. Echocardiography must be performed after the ablation procedure to investigate pericardial effusion.     

Multiple accessory pathways in pediatric patients with Wolff-Parkinson-White syndrome

The characteristics of multiple accessory pathways in children have not been previously studied. Records were reviewed of 317 consecutive pediatric patients with Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency catheter ablation at our institution. Twenty-eight patients (9%) had multiple pathways (a total of 64 pathways: 21 patients had 2, 6 had 3, and 1 patient had 4 pathways). The locations were left free wall (22 pathways), right free wall (19 pathways), posteroseptal (17 pathways), and anteromidseptal (6 pathways). Of these 64 pathways, 55 were ablated successfully without complications, 5 failed ablation, and 4 fasciculoventricular fibers did not require treatment. Three patients had a newly found pathway at the repeat session. Three patients had atrioventricular nodal reentrant tachycardia and the slow pathway area was modified. One patient had failed initial ablation and had a successful ablation using a 3-dimensional electroanatomic mapping system. Compared with patients with a single pathway, those with multiple pathways exhibited a higher incidence of antidromic tachycardia, a shorter anterograde accessory pathway effective refractory period (<250 ms), a longer fluoroscopic time (65 +/- 43 vs 39 +/- 46 minutes, p <0.05), and a larger number of unsuccessful attempts (9 +/- 16 vs 5 +/- 8, p <0.05). Success rate (92% vs 93%) and recurrence rate (1.7% vs 2.1%) were similar in both groups. This study demonstrates that multiple pathways are not rare in pediatric patients and that multiple pathways contrast with a single pathway in a variety of conduction properties.     

Tachycardia-induced cardiomyopathy: a reversible form of left ventricular dysfunction

Eight patients, aged 5 to 57 years, with uncontrolled symptomatic tachycardia for 2.5 to 41 years (mean 15) and significant left ventricular (LV) dysfunction in the absence of any other apparent underlying cardiac disease underwent evaluation. Incessant tachycardia was present for 0.5 to 6.0 years (mean 2.1) in 7 patients. One patient had an ectopic atrial tachycardia and 7 patients had an accessory atrioventricular pathway that participated in reciprocating tachycardia. Six patients underwent surgery; the ectopic focus was ablated in 1 patient and an accessory pathway was divided in 5 patients. One patient underwent open ablation of the His bundle and 1 patient underwent closed-chest ablation of the atrioventricular conduction system. Myocardial biopsy specimens were obtained from 5 patients, none of which yielded a specific diagnosis. Pretreatment radionuclide angiography demonstrated a mean ejection fraction (EF) of 19 +/- 9% (range 10 to 35%). Following tachycardia control a marked improvement in LV function was noted in 6 of 8 patients at rest and in 1 additional patient during exercise. The EF increased to 33 +/- 17% (range 16 to 56%) an average of 8 days after treatment and to 45 +/- 15% (range 22 to 67%) at late follow-up 3.5 +/- 40 months (mean 17) later (p less than 0.005). Seven patients remain asymptomatic 11 to 40 months (mean 22) after the corrective procedure and have resumed normal activities. These findings suggest that chronic uncontrolled tachycardia may result in significant LV dysfunction, which is reversible in some cases after control of the arrhythmia.     

The catheter ablation of accessory atrioventricular pathways using a radiofrequency]

Sixteen consecutive patients (5 males and 11 females) aged 40 +/- 22 years suffering for spontaneous symptomatic arrhythmias underwent attempted transcatheter ablation of an atrioventricular accessory pathway using radiofrequency current. Five patients had the WPW syndrome. The Kent bundle was located in the left free wall in 14 patients, in the right anteroseptal region in one patient and in the posteroseptal zone in one patient. A 7F catheter (Polaris, Mansfield) with a 4 mm2 distal electrode, was used for ablation positioned on the left atrioventricular annulus in the 13 patients with left free wall accessory pathways or at the right atrium in the two patients with right accessory pathways. Without general anesthesia, a mean of 12 +/- 9 applications of radiofrequency current were delivered between the large tip electrode and a large skin patch positioned on the left posterior chest. By using radiofrequency current, a successful clinical outcome was achieved in 14 of 16 patients (87%). In patients with concealed accessory pathways, accessory conduction was abolished in 10 of 11 patients, in 8 patients in the first radiofrequency session and in two other patients in a successful second procedure. In the 5 patients with the WPW syndrome, the anterograde conduction disappeared after the procedure but the retrograde conduction remained, although deteriorated, in 2 patients. One patient developed uncomplicated tibioperoneal thrombophlebitis and in 2 cases an elevated concentration of creatine kinase value was found. In one female patient with a concealed accessory pathway, the Kent bundle conduction reappeared 3 months after the procedure and was ablated in a second session.(ABSTRACT TRUNCATED AT 250 WORDS)