Radiofrequency ablation of accessory pathways in pre-excitation syndrome

Various parameters relating to the radio-frequency ablation of accessory pathways were studied in 53 patients (27 males, 26 females: mean age 38.5 [14-64] years) with a history of paroxysmal tachycardia (over 1 month to 50 years), shown to be caused by an accessory pathway (Wolff-Parkinson-White syndrome). In all patients the following values were obtained: (1) number of procedures necessary to achieve permanent blockage of the accessory pathway (1-4); (2) duration of each procedure (45-420 min); (3) duration of fluoroscopy (5-102 min); (4) number of necessary radio-frequency applications (1-48); and (5) cumulative energy per procedure. To ablate left-lateral pathways (n = 10) required fewer procedures, shorter duration per procedure, shorter fluoroscopy time, fewer current applications and less total energy than coagulation of right-sided pathways (n = 10). Those various parameters were greatest for ablation of septal and para-septal pathways (n = 9). Pathways which conducted only retrogradely (n = 15) were more difficult to ablate than those with anterograde conduction (n = 38). There were two complications. In one case a tension pneumothorax occurred after faulty puncture of the subclavian vein; in the other, the left ventricle was perforated causing an acute tamponade which required pericardiocentesis with subsequent suture closure of the perforation. It is concluded that, in principle, all accessory pathways, regardless of their conduction potential and site, can be ablated by a radio-frequency current.     

Radiofrequency catheter ablation of atrial flutter and atrial fibrillation

The existence of a physiological integration between the immune and endocrine systems has long been recognized. In spite of the abundant literature data on the presence of cells of the immune system in the testis, mast cells and eosinophil leukocytes have received little attention. We have studied the presence, distribution and numbers of mast cells and eosinophils in the testes of 12 mammalian species. Mast cells were frequently found in equine (stallion, ass and mule) and human testis, whereas eosinophils were nearly absent. On the contrary, eosinophils were abundant in the hare testis, while mast cells were lacking. Both cells types were present in high numbers in swine (wild and domestic boar) testis. Otherwise, mast cells and eosinophils were absent from the testicular parenchyma of several species (rat, dog, cat, bull and deer), although they were present, in most cases, around blood vessels in the tunica albuginea. The presence of high numbers of mast cells and/or eosinophil leukocytes in the testicular parenchyma of some species suggest a role for these cells in local regulatory pathways.     

Radiofrequency current catheter ablation of accessory atrioventricular pathways in Ebstein's anomaly

BACKGROUND: In patients with Ebstein's anomaly, localization of accessory pathways (APs) may be impeded by abnormal local electrograms recorded along the atrialized right ventricle and by the presence of multiple APs. The impact of these factors on radiofrequency (RF) current catheter ablation of APs has not been evaluated yet. METHODS AND RESULTS: Twenty-one patients with Ebstein's anomaly and reentrant atrioventricular tachycardias underwent electrophysiological evaluation and subsequent attempts at RF catheter ablation. Thirty-four right-sided APs were found, with 30 located along the atrialized ventricle. Local electrograms in this region were normal in 10 patients but fragmented in 11. Fragmented electrograms prevented the clear distinction between atrial and ventricular activation potentials as well as the identification of AP potentials. Right coronary artery mapping was performed in 7 patients. Abolition of all 26 APs was achieved in the 10 patients with normal local electrograms and in 6 of 11 patients with abnormal electrograms. Right coronary artery mapping allowed AP localization and ablation in 5 patients. In the 5 patients with abnormal electrograms and a total of 8 APs, 6 APs could not be ablated. Unsuccessfully treated patients received antiarrhythmic drugs. During 22 +/- 12 months of follow-up, 5 patients had clinical recurrences, including 4 who had undergone a successful RF procedure. CONCLUSIONS: In patients with Ebstein's anomaly and reentrant atrioventricular tachycardias, factors likely to account for failure of RF catheter ablation include an AP located along the atrialized right ventricle and the abnormal morphology of endocardial activation potentials generated in this region.     

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 in familial paroxysmal supraventricular tachycardia due to accessory atrioventricular pathways

Radiofrequency catheter ablation (RF-CA) has been widely used to cure paroxysmal supraventricular tachycardia (PSVT). However, its use has never been reported in familial PSVT caused by an accessory atrioventricular pathway (AP), which is known as one of the typical familial cardiovascular diseases. Two cases of using RF-CA for familial PSVT due to APs are presented, in a brother and sister, supporting a potential genetic role in the developmental failure to lose the atrioventricular connection during fetal life. The sister, a 24-year-old woman, had intermittent episodes of palpitation accompanied by chest pain for 2 years. An electrophysiologic study (EPS) confirmed her clinical tachycardia was atrioventricular reentrant tachycardia (AVRT) due to a left lateral concealed AP, which was subsequently successfully ablated with RF-CA. The brother, a 22-year-old man, had a 5-year history of paroxysmal palpitation. A resting electrocardiogram showed a right bundle branch block and left axis deviation with a delta wave. During his EPS, AVRT was reproducibly induced and a manifest AP was localized and then ablated at the left posteroseptal site, resulting in disappearance of the delta wave. PSVT, however, recurred 1 month later and during a repeat EPS the tachycardia was proved to be AVRT due to a right anterior concealed AP. The right anterior AP was successfully ablated with RF-CA. Both patients remained asymptomatic for more than 3 years following the successful ablation procedures.     

Radiofrequency ablation therapy of the posteroseptal accessory pathway

Among 652 patients with Wolff-Parkinson-White syndrome who underwent radiofrequency ablation in this laboratory, 139 (21%) were found to have a total of 146 posteroseptal accessory pathways. Ablation was conducted by the regular transvenous or transaortic approach; ablation from cardiac venous structures was used only if regular approaches were unsuccessful. Of the 146 posteroseptal accessory pathways, 94 were successfully ablated from the left posteroseptal region and 45 from the right posteroseptal region. In 3, successful ablation of the accessory pathway required delivery of the current to the proximal coronary sinus, and in 1 it required delivery of the current to both the atrial and ventricular aspects of the tricuspid valve at the right posteroseptum. Thus, the accessory pathway was successfully ablated in 143 (98%) of 146 instances or in 136 (98%) patients. In 3 patients, ablation was unsuccessful despite delivery of current to the left posteroseptum, the right posteroseptum, the proximal coronary sinus, and the middle cardiac vein. Seventy-seven (57%) patients with an initial success, including 9 patients with resumed preexcitation or recurrence of paipitations, underwent a follow-up electro-physiologic study 90 +/- 72 days after ablation. Of these 9 patients, the initial successful ablation site was the right posteroseptum in 7 and the left posteroseptum in 2. The accessory pathways were ablated successfully by subsequent trials in 8 patients, whereas in 1 the accessory pathway was severely damaged. Thus radiofrequency ablation of posteroseptal accessory pathways can be achieved by the regular transvenous or transaortic approach; delivery of current to the coronary sinus or middle cardiac vein is unnecessary in most patients.     

Radiofrequency catheter ablation of concealed atrioventricular accessory pathways using a "simultaneous pacing method"

The retrograde atrial potential at a successful ablation site is usually obscured by the wide and large ventricular potential during atrioventricular reentrant tachycardia or ventricular pacing, which makes it difficult to determine the appropriate ablation site for a concealed accessory pathway. A pacing maneuver named the "simultaneous pacing method" is proposed herein to differentiate the retrograde atrial potential from the ventricular potential for a successful ablation of the concealed accessory pathway. Catheter ablation was performed in 12 patients with a single left free-wall concealed accessory pathway. The atrial insertion site was determined by the simultaneous pacing method in six patients (group I) and by ventricular pacing in six patients (group II). In the simultaneous pacing method, electrograms recorded during ventricular pacing in the earliest retrograde atrial activation site are a fusion of the ventricular potential and the following retrograde atrial potential. When atrial and ventricular pacings are performed simultaneously (simultaneous pacing), the end portion of the electrograms recorded at the same site is solely the ventricular component, because atrial is activated earlier. The atrial potential can be confirmed during ventricular pacing in comparison with the electrograms during the "simultaneous pacing." Radiofrequency catheter ablation was successful in eliminating conduction through the accessory pathway in all 12 patients. The radiofrequency applications in group I were significantly fewer than those in group II (1.7 +/- 1.0 in group I, 5.3 +/- 3.2 in group II, P < 0.05). The total procedure time in group I was significantly shorter than in group II (57.8 +/- 15.7 vs 106.7 +/- 41.6 mins in group II, respectively, P < 0.05). The fluoroscopy time in group I was significantly shorter than in group II (54.0 +/- 7.9 vs 81.3 +/- 26.3 mins, respectively, P < 0.05). We were able to determine the atrial insertion site of accessory pathways by the simultaneous pacing method. The simultaneous pacing method was useful in eliminating concealed left free-wall accessory pathways.     

Radiofrequency ablation in a patient with tachycardia incorporating triple free wall accessory pathways and atrioventricular nodal reentrant tachycardia

Bone marrow cells from 15 patients with normal deoxyuridine (dU) suppression test results, 3 healthy subjects, and 11 patients with megaloblastic anemia caused by vitamin B12 or folate deficiency were examined for misincorporation of uracil into DNA. Cells were incubated with [5-3H] uridine for 2 hours and their DNA extracted. The DNA was hydrolyzed to deoxyribonucleosides with DNase 1, phosphodiesterase and alkaline phosphatase, and any dU present was separated from other deoxyribonucleosides by Aminex A6 chromatography. The quantity of dU/mg DNA and the radioactivity in the dU peak/mg DNA were then calculated. The results clearly showed that there was markedly increased uracil misincorporation into the DNA of vitamin B12- or folate-deficient marrow cells. Misincorporation of uracil into DNA may be an important biochemical lesion underlying both the megaloblastic change and the ineffectiveness of hematopoiesis in vitamin B12 and folate deficiency.     

Effect on coronary artery anatomy of radiofrequency catheter ablation of atrial insertion sites of accessory pathways

OBJECTIVES: The purpose of this study was to analyze the effects of radiofrequency catheter ablation of the atrial insertion site of accessory pathways on the angiographic appearance of coronary arteries. BACKGROUND: Radiofrequency catheter ablation of accessory pathways requires the application of energy to the endocardial surface of the atrioventricular groove adjacent to the major epicardial coronary arteries. A systematic analysis of the effect of radiofrequency ablation on coronary arteries has not previously been demonstrated. METHODS: Seventy consecutive patients with 76 accessory pathways (7 right free wall, 44 left free wall, 12 posteroseptal, 8 anteroseptal and 5 midseptal) were studied. Quantitative coronary angiography was performed before, immediately after and a mean of 69 +/- 42 days after radiofrequency catheter ablation. RESULTS: Coronary artery diameter adjacent to the ablating electrode was 2.6 +/- 0.9 mm before ablation, 2.7 +/- 0.9 mm immediately after ablation and 2.7 +/- 1.0 mm at the time of follow-up study. Angiographic findings were unchanged from baseline in 69 of 70 patients immediately after ablation and in all 70 patients at the time of follow-up study. CONCLUSIONS: Radiofrequency catheter ablation of the atrial insertion site of accessory pathways does not result in short-term angiographic changes in coronary artery anatomy.     

Radiofrequency catheter ablation in patients with common atrial flutter

BACKGROUND: Type 1 atrial flutter is produced by a reentry circuit located in the right atrium that can be interrupted applying radiofrequency in the inferior cava-tricuspid valve isthmus. AIM: To report our experience in the treatment of atrial flutter with radiofrequency ablation. PATIENTS AND METHODS: Nine patients (eight male) whose ages ranged from 6 to 72 years old were studied. Two patients had an operated congenital cardiopathy, two had high blood pressure, one was subjected previously to radiofrequency ablation due to a left paraspecific pathway, one developed a cardiac failure secondary to tachycardia and three did not have evidences of cardiopathy. RESULTS: In two patients, atrial flutter was not interrupted. In the other seven patients, radiofrequency ablation was successful. There were three relapses in the first month after the procedure, of these, two patients were successfully treated again. After a mean follow up of 4.5 months, these patients are asymptomatic and without antiarrhythmic drugs. Analysis of obtained signals, showed that radiofrequency that interrupted atrial flutter always occurred in zones of double potentials. CONCLUSIONS: Radiofrequency ablation is an effective treatment for atrial flutter and the zone of successful ablation is associated to the presence of double atrial potentials.     

Radiofrequency ablation of anomalous cardiac pathways: initial experience

AIM: To describe the initial experience of radiofrequency ablation of anomalous cardiac pathways in patients with supraventricular tachycardias. METHODS: A total of 10 patients with refractory supraventricular tachycardias mediated by anomalous cardiac pathways underwent electrophysiological assessment and attempted pathway ablation. RESULTS: Seven patients with left free wall atrioventricular pathways (two concealed) and two patients with dual atrioventricular nodal pathways had successful pathway ablations and have had no recurrence of arrhythmia. One patient with a concealed posteroseptal atrioventricular pathway was not able to be ablated. All patients tolerated the initial procedure well, but one developed pericarditis later. CONCLUSION: Radiofrequency ablation promises to be an important new technique for the management of patients with anomalous cardiac pathways and supraventricular tachycardias. Our initial experience has been favourable and comparable to other reported series with a high success rate and infrequent complications.     

High frequency current catheter ablation of accessory conduction pathways

Postoperative nausea and vomiting (PONV) are relatively common troublesome distressing symptoms. The incidence is reported to be as high as 20-51%. Ninety adult ASA I and II patients scheduled for laparoscopic gynecological or surgical interventions, were randomly and equally assigned to one of the three groups in the immediate postoperative period: Group 1 received 0.1 ml.kg(-1) normal saline intravenously, while Group 2 received 0.5 mg.kg(-1) ephedrine intramuscularly and Group 3 received 0.25 mg.kg(-1) propofol intravenously as preventive antiemetic therapy. Sixty-six, 33 and 50 percent of patients experienced nausea and vomiting syndrome in Group 1, 2 and 3 respectively. Both ephedrine and propofol proved to have antiemetic properties. Ephedrine treated group of patient had significant less emetic score than propofol. No significant hemodynamic changes were recorded in both groups.     

Intracranial microembolic signals during radiofrequency ablation of accessory pathways

Intracranial microembolic signals, probably caused by gaseous emboli, are readily detectable in patients undergoing radiofrequency ablation in the left side of the heart only. Clinical value of the detected signals could not be equivocably assessed, because only 2 of the patients who were examined (both emboli positive) had transient neurologic symptoms.     

Radiofrequency and cryoablation of atrial fibrillation in patients undergoing valvular operations

BACKGROUND: Previous studies have shown that the maze operation can restore sinus rhythm and atrial transport function in patients with chronic atrial fibrillation. The purpose of this study was to test the feasibility of the application of radiofrequency and cryoablation as an alternative to the classic maze operation. METHODS: Twelve patients undergoing mitral valve procedures were included in this study. Radiofrequency and cryoablation were applied to create lesions in both atria to simulate the classic maze operation. RESULTS: There were two surgical deaths. At the mean follow-up of 10.25 months for the remaining 10 patients; 6 were in sinus rhythm, 2 in atrial rhythm, 1 in paroxysmal atrial tachycardia, and 1 in atrial fibrillation. Doppler echocardiography at 6-month follow-up showed emergence of biatrial transport function in 3 patients and right atrial contractility in 8. At 12-month follow-up of 5 patients, Doppler echocardiography showed biatrial transport function in 3 and right atrial contractility in 4. CONCLUSIONS: Our modified maze procedure during valvular operation is effective for achieving an acceptable success rate to restore sinus rhythm and atrial transport function in patients with chronic atrial fibrillation.     

Anatomy-guided linear atrial lesions for radiofrequency catheter ablation of atrial fibrillation

The surgical atrial maze procedure has provided proof that atrial fibrillation can be cured by performing atrial incisions based on anatomical and electrophysiological principles. Preliminary reports of attempts at radiofrequency catheter ablation of atrial fibrillation utilizing an anatomy-based "linear incision" method have shown the feasibility of the method. However, postprocedural atrial fibrillation recurrence has been common and in addition new, uniform tachycardias have developed in some patients. Both of these outcomes may be in part due to incomplete or inconsistent lesion deployment. This article details the use of the CARTO system for deploying anatomy guided linear atrial lesions for the purpose of curing atrial fibrillation. The procedure is comprised of three phases, which are discussed in detail: (1) baseline map; (2) lesion deployment and; (3) lesion assessment. Using a single standard ablation electrode, lesions can be deployed safely, and complete lesions can be confirmed. Paradigms for right and left atrial incisions are proposed.     

Clinical recurrences after successful accessory pathway ablation: the role of "dormant" accessory pathways

INTRODUCTION: Recurrence of clinical symptoms after radiofrequency catheter ablation of an accessory atrioventricular pathway (AP) may be due to the late manifestation of an additional AP that was not detected during the initial ablation session. It was the purpose of this study to elucidate the phenomenon of these "dormant" APs. METHODS AND RESULTS: Of 1280 consecutive patients who underwent radiofrequency catheter ablation of an AP, 54 patients (4.2%) developed clinical symptoms postablation, necessitating a repeat ablation session. Recurrence of conduction over the AP targeted at the initial ablation session was found in 45 patients, whereas in the other 9 patients (0.7%) the manifestation of a previously unnoticed AP had caused symptom recurrence. Retrospective analysis of the data from these patients' ablation sessions revealed that the late manifesting AP was ablated at a site clearly different from that of the initially targeted AP, and that the manifestation of conduction over a previously "dormant" AP occurred significantly later than the recovery of a presumably ablated AP. Seven (78%) of the 9 "dormant" APs were concealed, and none exhibited decremental conduction properties. CONCLUSION: The incidence of clinical recurrences mediated by the late manifestation of conduction over a previously "dormant" AP is low. The lack of an anatomic vicinity of these predominantly concealed APs with the initially targeted AP and the lack of evidence for their presence during the initial ablation session suggest intermittent conduction as the most likely explanation for their late manifestation.     

Pulmonary vein stenosis after catheter ablation of atrial fibrillation

BACKGROUND: This report describes the complication of pulmonary vein stenosis with resultant severe pulmonary hypertension that developed in 2 patients after successful catheter ablation of chronic atrial fibrillation. METHODS AND RESULTS: Three months after successful catheter ablation of atrial fibrillation, both patients developed progressive dyspnea and pulmonary hypertension. Both were found to have severe stenosis of all 4 pulmonary veins near the junction with the left atrium. Balloon dilation of the stenotic pulmonary veins was performed in these patients, with improvement in dyspnea and pulmonary hypertension. CONCLUSIONS: The complication of pulmonary vein stenosis is potentially life-threatening, and the application of radiofrequency current within the pulmonary veins with standard catheter technology should be avoided. This complication can be treated with balloon dilation, although the long-term course is unknown.     

Radiofrequency catheter ablation for atrial flutter following orthotopic heart transplantation

Ureteral valves with ureteral strictures are rare and the differential diagnosis is difficult to establish. Four cases are reported to present these aspects.     

The effects of accumulated experience on radiofrequency ablation of accessory pathways

Increasing experience in radiofrequency ablation for accessory pathways appears to reduce the procedure time, radiation time and radiofrequency pulse number, and results in a higher success rate. However, the effect of a learning curve on this procedure from the perspective of location and conduction direction of accessory pathways has not been reported before. The purpose of this study was to determine the effect of accumulated experience on the outcomes of radiofrequency ablation for accessory pathways and on the duration of the procedure parameters by analyzing the results of a dedicated ablation team. The first 512 patients with a single accessory pathway treated in this laboratory were included for analysis of the procedure parameters with respect to locations and conduction directions of accessory pathways. The results showed that the average procedure time, radiation time, and radiofrequency pulse number differed significantly among the different subgroups (left free wall, right free wall, posteroseptal and anteromidseptal location; manifest or concealed conduction). All subgroups except the anteromidseptal pathways showed a significant improvement of the procedure parameters with increased ablation experience. Although the initial rate of improvement was similar among the different subgroups, the rate of improvement in left free wall pathways nearly reached a plateau after 120 ablation procedures. Thus it was concluded that a certain number of ablation procedures was necessary before achievement of a high success rate with shorter procedure and radiation times and a lower radiofrequency pulse number.     

Long-term results of radiofrequency catheter ablation in patients with multiple accessory pathways

Information on the long-term results of radiofrequency catheter ablation in a large group of patients with multiple accessory pathways (APs) was not available. This study included 858 patients with Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency catheter ablation: 73 patients (8.5%) had multiple APs. Sixty-six patients had 2 APs, 5 had 3 APs, 1 had 4 APs, and 1 had 5 APs. The most common combination pattern of these pathways were concealed APs (38 patients, 52%). Localization of accessory pathways showed a higher incidence of right free wall (22% vs 11%, p < 0.05), anteroseptal, and midseptal APs (9% vs 5%, p < 0.05) in patients with multiple APs than in patients with 1 AP. The most common anatomic sites for multiple APs were 2 APs in the left wall (21 patients, 28%). Although the success rate was similar (98% vs 99%, p > 0.05), procedure time (3.1 +/- 1.2 vs 2.0 +/- 1.1 hours, p < 0.05) and radiation exposure time (48 +/- 26 vs 29 +/- 19 minutes, p < 0.05) were longer in patients with multiple APs. The recurrence rate was higher in patients with multiple APs (9.5% vs 2.5%, p < 0.05), and the most common site of recurrent APs was in the left free wall (7.2%); in contrast, it was in the right free wall in patients with 1 AP. These findings demonstrated that a high success rate of radiofrequency catheter ablation was found in patients with multiple APs; however, the higher recurrence rate in patients with multiple APs should be considered.