Radiofrequency Ablation Therapy in Three Patients with Paroxysmal Atrial Tachycardia

Radiofrequency ablation therapy was performed in three patients with paroxysmal atrial tachycardia. There were two females and one male, aged 80, 63, and 75 years, respectiveiy. All three patients had induction of sustained atrial tachycardia. The tachycardia could be terminated by overdrive atrial pacing or atrial premature stimulation; it could also be terminated by intravenous bolus of adenosine triphosphate. In all three patients, there was no fragmented atrial electrograms recorded within the right atrium, and there was no ventriculo-atrial conduction during ventricular pacing. Tiie earliest atrial activation during tachycardia in these three patients was registered, respectively, at a site slightly posterior and inferior to the His-bundle recording site, at the anterior-superior border of Koch's triangle slightly posterior to the His-bundle recording site, and at the mid-lateral aspect of the right atrium over the crista terminalis at the junction of right atrial appendage and sinus venarum. Radiofrequency current was deiivered to the site of the earliest atrial activation during tachycardia through a 4-mm tip electrode catheter. It resulted in termination of tachycardia and ablation of the tachycardia focus. FoIIow-up observation over a period of 16, 15, and 4 months, respectively, in these three patients showed no recurrence of tachycardia. A repeat eiectrophysiological study was performed 52 and 63 days after ablation in two patients and revealed no induction of atrial tachycardia.     

Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in Children

Radiofrequency (RF) catheter ablation has been widely used in the treatment of cardiac arrhythmias. In atrioventricular nodal reentrant tachycardia (AVNRT), the experience has been predominantly in adults. The cardiac electrophysiological records of 18 consecutive children undergoing RF catheter AV node modification for AVNRT were reviewed. The patients (10 females, 8 males) were 8.2–17.9 years of age (mean 13.6 ± 3.0), weight 15.2–88.1 kg (mean 52.2 ± 20.8), and height 103–190 cm (mean 157.1 ± 21.7). Thirteen were on antiarrhythmic medications (1–3, average 1.5 drugs/day). All drugs were discontinued 48 hours prior to the ablations. The procedures were performed under sedation and local anesthesia. Pre- and post-AV node modification electrophysiological studies were performed in all procedures. The 18 patients underwent a total of 25 procedures (1.39 ± 0.61 per patient): the anterior approach aimed at the antegrade fast pathway in the first four patients and the posterior approach aimed at the slow pathway in the remainder. Thenumber of energy applications was 8–54 (19.8 ± 10.7) per procedure. The maximum energy used in each procedure was 30–50 watts (33.8 ± 8.4). The average energy was 24–50 watts (33.0 ± 6.8). The fluoroscopy time was 7.1–73.4 minutes (29.9 ± 20.0) per procedure, for a total catheterization time of 228–480 minutes (300.3 ± 59.1). Preablation spontaneous or induced AVNRT (cycle length 310.4 ± 55.0 msec) was seen in all except one who had the arrhythmia (cycle length 270 msec) on surface ECG. In 22 of 25 studies, the AH interval measured 67.4 ± 13.2 msec pre- and 98.7 ± 58.4 msec post-AV node modification (P < 0.02). Procedures were initially successful in 16 (89%) of 18 patients. One patient developed complete AV block requiring DDD pacemaker and has since recovered normal AV conduction. Transient third- or second-degree block was seen in four. Other complications included airway obstruction in one and excessive emesis in another. In follow-up of 2–26 months (13.0 ± 7.3), one patient underwent surgical ablation for failed initial RF catheter ablation, and two underwent successful RF procedures for recurrences. RF catheter AV node modification for AVNRT in children is a useful technique. Under ideal circumstances, it is safe and efficacious. Follow-up to determine the potential long-term complications is necessary.     

Palpitations Occur Frequently Following Radiofrequency Catheter Ablation for Supraventricular Tachycardia, But Do Not Predict Pathway Recurrence

Radiofrequency ablation of extranodal pathways is an effective treatment for supraventricular tachycardia, but late recurrences of pathway conduction do occur. To determine if recurrence of palpitations following ablation predicts pathway recurrence, we interviewed 77 patients who were at Jeast 4 weeks status-post successful ablation of an accessory pathway (43 overt, 11 concealed)or a slow pathway (23)for AV nodal reentrant tachycardia. Palpitations were reported by 45 (58%)patients postablation, and 28 (36%)patients reported palpitations lasting ≥10 seconds and/or felt their symptoms represented recurrent tachycardia (major palpitations). Repeat electrophysiological testing was performed 3 months postablation in 53 patients, including 34 patients with palpitations (22 with major symptoms). Eight (10%)patients had recurrent pathway conduction demonstrated on repeat testing: two had no symptoms prior to restudy and six had major symptoms. One patient had major symptoms, but was found to have inducible atrial tachycardia and not pathway recurrence on restudy. Thus, 15 (68%)of 22 patients with major symptoms who were restud-ied had no pathway recurrence or inducible arrhythmia to explain their symptoms. Of the 24 patients not restudied, none has had documented recurrent tachycardia or overt pathway conduction by electrocardiogram over a mean follow-up of 335 ± 138 (range 132–616)days. Thus, palpitations, including palpitations reminiscent of preablation symptoms, are common following radiofrequency ablation and often do not predict pathway recurrence. Repeat electrophysiological testing is frequently required to document long-term success of radiofrequency ablation for supraventricular tachycardia in patients with recurrence of major symptoms.     

经导管射频消融治疗特发性室性心动过速患者的护理

目的探讨经导管射频消融治疗特发性室性心动过速患者的护理方法。方法回顾性分析75例行导管射频消融治疗的特发性室性心动过速患者的临床资料。结果发生术后并发症3例,其中穿刺点血肿2例、心脏压塞1例,经精心治疗和护理后均痊愈出院。结论经导管射频消融治疗特发性室性心动过速患者安全有效,手术前后需要密切观察、精心护理、及时发现并协助处理各种并发症。     

Radiofrequency Catheter Ablation of Refractory Ventricular Tachycardia

Transcatheter radiofrequency ablation of the arrhythmia focus was attempted in a 68-year-old patient with recurrent ventricular tachycardia, both spontaneous and inducible by programmed ventricular stimulation despite treatment with multiple antiarrhythmic drugs. The procedure was performed under local anesthetic without complication. The arrhythmia was not inducible immediately following ablation or 5 days later, and during 5 months follow-up there has been no spontaneous recurrence.     

Spontaneous Accelerated Junctional Rhythm: An Unusual but Useful Observation Prior to Radiofrequency Catheter Ablation for Atrioventricular Node Reentrant Tachycardia in Young Patients

Between May 1990 and March 1995, 5 of 29 young patients (ages 4.2–25 years; median 14.1 years) undergoing RF ablation for atrioventricular node reentrant tachycardia (AVNRT) presented with spontaneous accelerated junctional rhythm (AJR) (CL = 500–750 ms), compared to 0 of 58 age matched controls undergoing RF ablation for a concealed AV accessory pathway (P = 0.004). In 3 of the 5 patients with AVNRT and AJR, junctional beats served as a trigger for reentry. During attempted slow pathway modification in the five patients with AVNRT and AJR, AVNRT continued to be inducible until the AJR was entirely eliminated or dramatically slowed. These 5 patients are tachycardia-free in followup (median 15 months; range 6–31 months) with only 1 of the 5 patients continuing to experience episodic AJR at rates slower than observed preablation. Episodic spontaneous AJR is statistically associated with AVNRT in young patients and can serve as a trigger for reentry. Successful modification of slow pathway conduction may be predicted by the elimination of AJR or its modulation to slower rates, suggesting that the rhythm is secondary to enhanced automaticity arising near or within the slow pathway.     

Successful Radiofrequency Current Catheter Ablation of Sustained Ventricular Tachycardia

We performed radiofrequency current catheter ablation in two patients with nonischemic sustained ventricular tachycardia (VT). In one patient, two morphologically distinct VTs were induced by electrical stimulation. One showed right bundle branch block pattern and the other left bundle branch block pattern. The earliest site of activation during each VT was determined at the septum of the right ventricle. However, these two sites were close to the His-bundle elecfrogram recording area. In the other patient, a VT with a left bundle branch block pattern occurred spontaneously after the administration of isoproterenol. The earliest site of activation during VT was determined at the outflow tract of the right ventricle. During tachycardia, radiofrequency current ablation (40 W ± 30 sec) was delivered to the earliest site of activation, A few seconds after fulguration, each VT was terminated and additional radio-frequency currents were given near these sites. After the ablation, VT could not be induced by the electrical stimulations, nor did it recur. No side effects were observed and the atrioventricular conduction remained intact. We feel that nonischemic VTs could possibly be treated by using radiofrequency current catheter ablation.     

临床护理路径在射频消融术治疗室上性心动过速健康教育中的应用

目的比较临床护理路径进行健康教育与传统方法进行健康教育的护理效果差别。方法将89例室上性心动过速行射频消融术患者,按病例单双号分成2组,观察组采用临床护理路径进行健康教育,对照组采用传统方法进行健康教育,并对两组的护理效果进行比较。结果两组患者的心理状态、健康知识掌握情况、行为改变、住院日、满意度差异均有统计学意义（P〈0．01）,观察组术后不良反应发生率少于对照组（P〈0．05或P〈0．01）。结论应用临床护理路径对射频消融术患者实施健康教育,能促进患者更好地掌握健康教育知识,降低术后不良反应、住院日及医疗费用,提高满意度。     

Usefulness of Intravenous Propofol Anesthesia for Radiofrequency Catheter Ablation in Patients with Tachyarrhythmias: Infeasibility for Pediatric Patients with Ectopic Atrial Tachycardia

General anesthesia is sometimes required during radiofrequency catheter ablation (RFCA) of various tachyarrhythmias because of an anticipated prolonged procedure and the need to ensure stability during critical ablation. In this study, we examine the feasibility of using propofol anesthesia for RFCA procedure. There were 150 patients (78 male, 72 female; mean age 30 years, range 4-96 years) in the study. Electrophysiologic study was performed before and during propofol infusion in the initial 20 patients and was performed only during propofol infusion in the remaining 130 patients. In the initial 20 patients, propofol infusion increased the sinus rate and facilitated AV nodal conduction. The accessory pathway effective refractory period, as well as the sinus node recovery time, atrial effective refractory period, and ventricular effective refractory period were not significantly changed. There were 152 tachyarrhythmias in 150 patients (24 atrial flutter, 31 AV nodal reentrant tachycardia, 68 AV reciprocating tachycardia, 12 ventricular tachycardia, and 17 atrial tachycardia). Most (148/152) tachycardias remained inducible after anesthesia and RFCA was performed uneventfully. However, in four of the seven pediatric patients with ectopic atrial tachycardia, the tachycardia terminated after propofol infusion and could not be induced by isoproterenol infusion. Consequently, RFCA could not be performed. Intravenous propofol anesthesia is feasible during RFCA for most tachyarrhythmias except for ectopic atrial tachycardia in children.     

Curative Radiofrequency Catheter Ablation for Permanent Junctional Reciprocating Tachycardia

Two patients with the permanent form of junctional reciprocating tachycardia successfully treated with the radiofrequency catheter ablation technique are described. In both patients a reentrant tachycardia utilizing a conceoled slow conducting posterior septal accessory pathway for retrograde conduction was demonstrated. Radiofrequency current was delivered below the coronary sinus orifice. The procedure resulted in ablation of the accessory pathway conduction in both patients. During the follow-up, both patients remained free from tachycardia on no medication. This report demonstrates that the arrhythmogenic substrate of the permanent junctional reciprocating tachycardio can be easily suppressed by means of the radiofrequency catheter technique.     

Radiofrequency Catheter Ablation of Sinus Node Reentrant Tachycardia

Sinus node reentrant tachycardia is a relatively uncommon (5%-5%) form of recurrent paroxysmal supraventricular tachycardia (SVT). We describe a case of symptomatic sinus node reentrant tachycardia in a 67-year-old male with ischemic heart disease, congestive heart failure, and depressed ventricular function. Adenosine administered during an electrophysiology study caused prolongation of the tachycardia cycle length due to atrial cycle length prolongation (without atrio-His prolongation) prior to tachycardia termination. Right atrial mapping revealed the earliest site of atrial activation in the high lateral right atrium just below the superior vena cava. Low energy (10 and 20 W) radiofrequency lesions were applied ai this site with termination of the tachycardia within 3 seconds of radiofrequency energy delivery. Tachycardia could not be reinduced after delivery of the radiofrequency lesions. The sinus node function immediately and 6 weeks after radiofrequency catheter ablation remained normal and the patient was without clinical recurrence of SVT. Mapping of sinus node reentrant tachycardia and elimination of the reentrant circuit with radiofrequency catheter ablation is possible without causing sinus node dysfunction. Adenosine causes prolongation of the atrial cycle length followed by termination of sinus node reentrant tachycardia.     

Late Potentials Are Unaffected by Radiofrequency Catheter Ablation in Patients with Ventricular Tachycardia

Reentrant ventricular tachycardia is dependent on an area of myofibers, embedded in scar tissue, which exhibit slow conduction. Late potentials recorded by signal-averaged electrocardiography appear to correspond to these zones of slow conduction and frequently are present in patients with VT. We hypothesized that elimination of inducible VT by catheter-mediated ablation of critical areas of slow conduction would alter late potentials. Four patients underwent catheter ablation in which radiofrequency current was delivered to zones of slow conduction exhibiting isolated mid-diastolic potentials that could not be dissociated from the tachycardia. The four patients had developed VT (cycle length 382 ± 50 msec; mean ± SEM) 13–180 months after inferior myocardial infarction. Late potentials were present in each patient before catheter ablation was attempted. Although VT was not inducible in any patient immediately after ablation, late potentials were still present in all four patients and there was no significant difference in the QRS duration (136.5 ± 4.0 msec postablation; 135.7 ± 4.5 msec preablation), root mean square voltage in the terminal 40 msec of the QRS (10.0 ± 1.0 μV postablation; 5.9 ± 0.4 μV preablation). or in the duration of the low amplitude signal (69.2 ± 2.0 msec postablation; 62.7 ± 3.4 msec preablation). At follow-up electrophysiology study performed 14 ± 7 days after ablation, one of the four patients had inducible VT. In conclusion, late potentials persist even after successful radiofrequency catheter ablation and do not appear to be useful for predicting results of follow-up electrophysiology study.     

Radiofrequency Catheter Ablation of Concealed Atrio-His Bypass Tract Involved in Paroxysmal Supraventricular Tachycardia

In a patient with paroxysmal supraventricular tachycardia and without any evidence for preexcitation syndrome or dual atrioventricular (AV) nodal pathways, the tachycardia reentry circuit consisted of the AV node as an antegrade limb of the circuit and a concealed atrio-His bypass tract located in the posterior septum as a retrograde limb. During the tachycardia, the atrial potentials in the septal region and coronary sinus were inscribed in the QRS complex, and the earliest atrial activation site was located in the posterior septum. Ventricular extrastimulation at critically short intervals reproducibly demonstrated a ventriculo-His-atrial activation sequence with the same earliest retrograde atrial activation site as that during the tachycardia. Radiofrequency energy (20 W) was applied to this earliest activation site during ventricular pacing, which resulted in complete ventriculo-atrial block within 2 seconds after energy application. The antegrade AV conduction property was not affected and the tachycardia was no longer induced. The patient has been free from tachycardia attack for a follow-up period of 8 months. Therefore, radiofrequency catheter ablation for an atrio-His bypass tract is feasible without inducing any AV conduction disturbance.     

Radiofrequency Catheter Ablation of AV Nodal Reentrant Tachycardia in Situs Inversus Totalis

A 41‐year‐old male with situs inversus totalis had paroxysmal supraventricular tachycardia. On electrophysiology study, the mechanism of the tachycardia was determined as slow/fast atrioventricular nodal reentrant tachycardia and slow pathway was successfully performed under fluoroscopic guidance.     

First Lessons from Radiofrequency Catheter Ablation in Patients with Ventricular Tachycardia

Fourteen patients (12 men, 2 women; 61 ± 9 years) with ventricular tachycardia and underlying heart disease underwent an attempt at radiofrequency energy catheter ablation. Twelve patients had coronary disease and two patients had dilated cardiomyopathy. Two patients had two clinical tachycardias, the ejection fraction was 38%± 11%. All tachycardias were inducible and hemodynamically well tolerated (cycle length = 357 ± 56 msec). Ablation was initially successful in nine patients (no tachycardia inducible after ablation and before discharge). Two patients had recurrences (in-hospital and 4 months) and one patient had a tachycardia of a different morphology, which was also successfully ablated. Ablation was overall successful in seven patients and unsuccessful in seven patients (including all patients with cardiomyopaihy). Mid-diastolic potentials were observed in all the patients in whom ablation was successful but not observed in four of seven unsuccessful patients. The successful patients remain free of recurrences at 9 ± 8 months follow-up. Conclusions: (1) in ventricular tachycardia following an old infarction radiofrequency energy ablation is possible with a high success rate if a critical component of the tachycardia circuit can be localized. Localizing isolated mid-diastolic potentials and ensuring these potentials are part of the reentrant circuit with concealed entrainment can help to enhance the results. (2) A negative predischarge electrophysiological study may be predictive of success.     

Titration of Power Output During Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia

Radiofrequency lesions in the anterior, superior aspect of the tricuspid annulus result in selective elimination of fast pathway function in patients with typical atrioventricular (AV) nodal reentry tachycardia. This technique is simple and effective, but has been associated with a significant risk of inadvertent complete AV block. The purpose of this study was to compare the safety and effectiveness of two different techniques for radiofrequency catheter ablation of the fast AV nodal pathway. Initially, a fixed power output was used at each target site. This method was compared retrospectively to a newer technique where power output was gradually incremented at each site. Radiofrequency power was initially applied at 10 watts for 10–15 seconds. If no junctional ectopy or a change in PR intervoi was seen, power output was incremented by 2 to 4 watts every 10 to 15 seconds up to a maximum of 30 watts. Thirty seven of 38 (96%) patients treated using this incremental power output were cured of their AV nodal reentry tachycardia. None of these patients developed inadvertent complete AV block. In contrast, 92% of historic controls treated with a fixed power output between 20 and 30 watts achieved a primary success and nine of these 89 (10%) historic controls developed inadvertent complete AV block (P = 0.04). There was no difference in the amplitudes of atrial, His, or ventricular electrograms at the effective sites between the two groups. Conclusions: (1) the anterior approach to radiofrequency catheter ablation of typical AV nodal reentry is associated with a significant risk of inadvertent complete AV block if a fixed power output is used; (2) starting at low power and gradually incrementing the output during radiofrequency energy application reduces the risk of complete AV block; (3) this incremental technique does not compromise efficacy.     

Catheter Ablation of Canine Myocardium with Radiofrequency Energy

High energy direct-current shocks delivered via an electrode catheter have been used to ablate the atrioventricular junction since 1981.¹ This technique has also been adapted for ablation of other cardiac tissues including the atrium, posterior interatrial septum and ventricular myocardium. The limitations of this technique include inadequate control of the energy source, poor understanding of the mechanisms of myocardial injury, and untoward complications possibly related to barotraumatic injury. Radiofrequency energy has been shown to create ablative injury when delivered lo the myocardium via standard electrode catheters. This report will review our experience with radiofrequency catheter ablation of the canine myocardium with specific emphasis on the biophysical aspects of lesion formation.     

Radiofrequency Catheter Ablation of Atrial Tachycardia with Unusual Left Atrial Sites of Origin: Report of Two Cases

Two cases of successful radiofrequency catheter ablation of adult-onset atrial tachycardia originating from the left atrium adjacent to the mitral annulus are presented. Endocardial catheter activation mapping performed by retrograde or atrial transseptal approach revealed presystolic activation at the successful ablation site in both patients, and fractionation during sinus rhythm and tachycardia in one. The 12 lead electrocardiogrnphic P wave appearance was suggestive of a left atrial tachycardia origin in both cases.