Radiofrequency catheter ablation therapy in elderly patients with supraventricular tachycardia

In the present study, long-term and short-term rat preparations were used to develop a model for investigating external anal sphincter (EAS) reflexes in intact and spinal cord-injured (SCI) rats. In this model, EAS distension with an external probe elicits reflex contractions of the EAS in intact, unanesthetized animals. At 2 h after spinal cord transection, none of the lesioned animals displayed EAS EMG activity. In fact, once distended, the EAS was incapable of maintaining closure of the anal orifice. Over a period of 4 days, spinalized animals developed a hyperreflexia of the EAS response. By 48 h, the rectified, integrated EAS EMG was significantly elevated in comparison with nonlesioned controls (EAS hyperreflexia). In addition, the duration of the EAS EMG bursts in response to sphincter distension had significantly increased. At 6 weeks after injury, the EAS was significantly hyperreflexic as measured by EMG burst duration and burst area. As with intact animals, posttransection EAS reflexes were highly anesthesia sensitive. These studies indicate that (1) brief distension of the anal orifice is sufficient to evoke a physiologically relevant reflexive activation of the EAS in the rat, (2) the 2- to 24-h postinjury areflexia observed in these experiments may be a suitable model for the study of spinal shock, and (3) the observed EAS hyperreflexia after chronic SCI may represent the permanent effects of removing descending inhibitory circuits and segmental plasticity, making this reflex an appropriate measure of defecatory dysfunction after spinal cord injury.     

Radiofrequency catheter ablation of supraventricular tachycardia in an adult with corrected tetralogy of Fallot

An 18 year old female with Fallot's tetralogy had undergone complete repair at thirteen years of age. Two years later she first presented a wide complex right bundle branch block tachycardia at a rate of 220 beats/min which could not be controlled on intravenous verapamil. Electrical shock successfully converted tachycardia to sinus rhythm, which showed typical Wolff-Parkinson-White syndrome. On electrophysiological study, the ortodromic tachycardia was found to be due to left lateral atrioventricular accessory pathway, which was ablated by radiofrequency catheter ablation. One year later she was symptom-free without antiarrhythmic medication.     

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 catheter ablation in monomorphic ventricular tachycardia

Twenty patients with symptomatic monomorphic ventricular tachycardia (VT) underwent radiofrequency (RF) energy catheter ablation. Four patients (20%) had underlying heart disease (1 prolapse mitral valve, 1 dilated cardiomyopathy and 2 myocarditis). Five patients (25%) had left sided VT and right sided VT in the remainder (75%). Radiofrequency catheter ablation was initially successful in all patients without major complication. Recurrence occurred in three patients (15%). In conclusion, RF ablation is an effective treatment for symptomatic monomorphic right and left sided VT especially in patients who do not want long term antiarrhythmic agents.     

Radiofrequency catheter ablation of ventricular tachycardia in 26 patients

Electrophysiology study and radiofrequency catheter ablation (RFCA) were performed in 26 patients with refractory sustained ventricular tachycardia (VT). After induction of VT, 12-lead electrocardiogram (ECG) was recorded and QRS morphology and axis of induced VT were studied to identify the origin of VT. The precise site of VT origin were localized by pace mapping and activation mapping carefully. RF energy was delivered through a big-tip deflectable electrode catheter when the earliest site of endocardial activation and a high-frequency and low-amplitude potential of Purkinje fiber, preceding surface QRS by more than 25 ms, were identified and/or a pace map was obtained showing identical QRS complexes in at least 11 of 12 ECG leads. VTs were ablated successfully in 24 of 26 patients (success rate was 92%). For successful ablation, it is essential that the pace map QRS morphology in 12 leads should be identical with that in spontaneous or induced VT as far as possible in performing pace mapping. Pace mapping is safe, simple and has no unfavourable effect hemodynamics although it takes longer time. Activation mapping takes shorter time and has a high success rate. QRS configuration in spontaneous VT can help to localize the site of VT origin. Deliberate mapping at the site suggested to bo the origin of VT by surface ECG can shorten the duration of mapping and increase the success rate of RFCA. RFCA of VT in patients without structural heart disease is effective, safe, and has a high success rate, so it may be considered as an early therapy for these patients.     

Catheter ablation of incessant ventricular tachycardia

Emergency catheter ablation of ventricular tachycardia was performed in 22 patients. All patients had incessant ventricular tachycardia that persisted for > or = 12 h/day and was only transiently terminated by stimulation techniques, anti-arrhythmic drugs or cardioversion. Radiofrequency catheter ablation was carried out using entrainment criteria as well as endocardial activation mapping. Ventricular tachycardia was terminated in 91% of cases, one patient underwent map-guided surgery and the remaining patient was managed by anti-arrhythmic drugs. After the initial ablation procedure 3 of the 20 patients who could be acutely managed died in hospital: one patient in refractory heart failure 24 h following ablation, one patient suddenly 10 days following ablation on the ward and another patient 4 weeks following ablation because of septicemia. Four patients underwent elective implantation of a cardioverter-defibrillator because of inducible ventricular tachycardia, and another patient underwent elective map-guided surgery. Overall, 12 patients were discharged without any additional non-pharmacologic intervention; 5 of them were free of anti-arrhythmic drugs and 7 patients had previously received ineffective medication including continuation of amiodarone in 3 patients. These results indicate that radiofrequency catheter ablation may play a role in the treatment of patients with incessant ventricular tachycardia. Thus, non-pharmacologic management of incessant ventricular tachycardia is associated with a high hospital mortality rate especially in surgically treated patients. Catheter ablation using radiofrequency current is the preferred approach for acute palliation.     

Radiofrequency catheter ablation of right ventricular outflow tract tachycardia in a preschooler

A 3-year-old girl presented with a febrile illness complicated by right ventricular outflow tract tachycardia, which persisted after resolution of the presumed viral infection. The tachycardia was intermittent, but was significantly exacerbated by exercise. Radiofrequency ablation (RFA) of the ectopic focus was successfully performed and the child remains free of tachycardia 12 months later. A review of the literature suggests that RFA in children is increasingly seen as a safe and convenient option for the treatment of supraventricular tachycardia, whereas the management of ectopic ventricular tachycardia in pediatric practice has not been well defined.     

Radiofrequency catheter ablation of sustained monomorphic ventricular tachycardia in hypertrophic cardiomyopathy

INTRODUCTION: Incessant monomorphic ventricular tachycardia (VT) with a right bundle branch block morphology and a northwest axis is a rare arrhythmic complication in a patient with hypertrophic cardiomyopathy and apical left ventricular aneurysm. METHODS AND RESULTS: The origin of this VT was localized using the following criteria: the presence of entrainment without fusion, equal intervals from the stimulus to the beginning of the QRS complex and from the electrogram to the QRS complex during VT, and the first postpacing interval identical to the tachycardia cycle length. Radiofrequency energy applied to the septoapical part of the apical left ventricular aneurysm terminated the tachycardia within 2 seconds. CONCLUSION: Using criteria to guide radiofrequency (RF) ablation of VT in patients with coronary artery disease, an incessant monomorphic VT in a patient with hypertrophic cardiomyopathy was successfully ablated.     

Radiofrequency catheter ablation of atrioventricular nodal reentry tachycardia utilizing nonfluoroscopic electroanatomical mapping

The advent of catheter ablation stimulated extensive research into anatomical localization of the pathways involved in atrioventricular nodal reentrant tachycardia (AVNRT). Conventional electrophysiological methods that attempt to correlate intracardiac electrograms with two-dimensional fluoroscopic anatomy are limited by the relative inaccuracy and poor reproducibility of this technique, and the requirement for high levels of radiation exposure. A new method of nonfluoroscopic electroanatomical mapping utilizes magnetic field sensing with a specialized catheter to construct three-dimensional electroanatomical endocardial maps of selected heart chambers with spatial resolution of < 1 mm. This system can be used in patients undergoing catheter ablation for AVNRT to create accurate maps of Koch's triangle and to guide application of radiofrequency energy. Initial experience in 14 patients suggests efficacy and safety comparable to conventional mapping and ablation techniques. Further evaluation may confirm the potential benefits of this system with respect to success rates, complications, procedure time, and radiation exposure.     

Catheter ablation of incessant ventricular tachycardia: acute and long-term results

SUBJECTS: Seventeen patients with incessant ventricular tachycardia refractory to anti-arrhythmic therapy underwent catheter ablation between 1987 and 1993. Fifteen patients had coronary heart disease and two had dilated cardiomyopathy. The mean age of the patients was 65 +/- 8 and the mean left ventricular ejection fraction was 31 +/- 9%. METHODS: Ablation sites were selected on the basis of endocardial activation mapping, concealed entrainment or bundle branch mapping. Catheter ablation was performed with direct current in nine patients and with radiofrequency energy in eight patients. Incessant ventricular tachycardia was terminated by catheter ablation in all 17 patients. RESULTS: One patient died after the ablation procedure due to pericardial tamponade. During electrophysiological testing 5-14 days later, 7 of 16 patients (44%) had inducible sustained or non-sustained ventricular tachycardia. Five of them underwent implantation of an automatic cardioverter/defibrillator, and three of these experienced discharges of the device during a mean follow-up of 30 +/- 12 months. another patient underwent implantation of a cardioverter/defibrillator after spontaneous recurrence of ventricular tachycardia. Out of the nine patients without inducible ventricular tachycardia, one died as a result of sudden cardiac death, and another had spontaneous ventricular tachycardia. Thus, ventricular tachycardia recurred clinically in 6 of 16 patients (38%), in whom ventricular tachycardia with the same morphology as that of the ablated ventricular tachycardia could be determined only in one patient. CONCLUSION: Catheter ablation is the method of choice for the emergency treatment of patients with incessant ventricular tachycardia. Due to the high risk of recurrence, additional anti-arrhythmic management, such as the implantation of a cardioverter/defibrillator, has to be considered.     

Radiofrequency ablation of a fascicular tachycardia after orthotopic cardiac transplantation

Serology is a critical component in the diagnosis of amebic liver abscess. However, in areas endemic for amebiasis there is a high background level of seropositivity for amebiasis (owing to previous infection with Entamoeba histolytica), which may complicate the interpretation of a positive serologic test result. Recently, we reported that serologic tests based on recombinant E. histolytica antigens might offer improved diagnosis of current invasive amebiasis because they apparently differentiated active infection from past exposure to the parasite. To confirm this finding, we have performed a longitudinal study on 20 patients with amebic liver abscess by examining their seroreactivity over time with recombinant versions of two major E. histolytica proteins, the serine rich E. histolytica protein (SREHP), and the 170-kD subunit of the galactose-specific adhesin. We found that more than 50% of the patients examined had become seronegative by one or both recombinant tests within 180 days of their diagnosis of amebic liver abscess. In the case of the recombinant SREHP-based tests, 12 patients had become seronegative 90 days after presentation. In contrast, all patients remained seropositive by a standard conventional test, an indirect hemagglutination test, at more than six months after presentation. Our study shows that patients lose seroreactivity with the recombinant SREHP or 170-kD antigen-based tests more rapidly than with a conventional serologic test; this may make them useful for the serologic diagnosis of amebiasis in endemic areas.     

Radiofrequency catheter ablation in symptomatic ventricular arrhythmia

Xenopus embryos were exposed to 200 ppb 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for 5 days from the 2- to 8-cell stage of cleavage to the early larval stage. Larvae that developed generalized edema were collected at 7 days after the end of TCDD exposure for light and electron microscopic studies. Erythrocytes in the peripheral blood of the edematous larvae were examined. Between 0.3 and 33.9% of identifiable erythrocytes of exposed larvae had dilated perinuclear cisternae. Furthermore, some had extremely condensed nuclear chromatin usually coalesced against 1 pole of the nuclear membrane and overall compacted cytoplasm. The erythrocytes showing nuclear condensation were phagocytosed by macrophages. These features are typical of cells undergoing apoptosis. Anemia is 1 symptom of TCDD toxicity in various animal species, including mammals. In this study, we demonstrate that TCDD induces apoptotic cell death in circulating erythrocytes of Xenopus larvae, which may be 1 cause of anemia in this species.     

Radiofrequency ablation in the therapy of supraventricular and ventricular arrhythmias

We summarize our experience with RF-ablation in 70 patients with symptomatic tachycardia (38 females and 32 males, age 25-73 years). 19 patients with AV reentry tachycardia in WPW-syndrome, 28 patients with node reentry tachycardia (AVNRT), 10 patients with ventricular tachycardia, 9 patients with atrial fibrillation and 4 patients with atrial flutter were treated. The primary success rate in the whole patient group is 87% and the longterm success rate (up to 1 year) 81%. RF-ablation of tachycardia is a highly effective therapy. The patients are free of symptoms and need no further medication. In patients with AVNRT in WPW-syndrome and ventricular tachycardia (structurally normal heart), RF-ablation is the therapy of choice. 32/70 patients were treated on an outpatient basis.     

Radiofrequency catheter ablation for idiopathic right ventricular tachycardia with special reference to morphological variation and long-term outcome

We have cloned and sequenced a beta subunit of integrin from a cDNA library of crayfish hemocytes. This beta integrin shows great similarity to beta integrin subunits from other animals; the highest is towards beta pat-3 from Caenorhabditis elegans followed by beta PS from Drosophila melanogaster. By immunoblotting with antibodies raised towards a synthetic peptide corresponding to a part of the cytoplasmic region of the deduced protein sequence, it was shown that the integrin is present in the membrane of the hemocytes. This is the first integrin found in hemocytes of an invertebrate animal and this finding opens the door for further investigations on integrins and their role in the invertebrate immune system.     

Radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome

OBJECTIVE: To report on the experience with radiofrequency catheter ablation of accessory atrioventricular pathways in patients with Wolff-Parkinson-White syndrome in terms of the duration of fluoroscopy exposure to the patient and the operator and the effect of accessory-pathway location and operator experience on the success rate. DESIGN: Retrospective review. SETTING: Tertiary care university hospital. PATIENTS: Two hundred consecutive patients with Wolff-Parkinson-White syndrome who underwent radiofrequency catheter ablation between September 1990 and June 1992. INTERVENTIONS: Electrophysiologic study and radiofrequency catheter ablation. MAIN OUTCOME MEASURES: Success rate, duration of fluoroscopy, complications and long-term follow-up. RESULTS: Of the 224 accessory pathways in the 200 patients 135 were left free wall, 47 posteroseptal, 32 right free wall and 10 anteroseptal. The overall success rate increased from 53% in the first 3 months of the study period to 96% in the last 3 months. The success rate depended on the location of the accessory pathway. The duration of fluoroscopic exposure decreased from 50 (standard deviation [SD] 21) minutes in the first 3 months to 40 (SD 15) minutes in the last 3 months (p < 0.05). Complications occurred in 3.5% of the patients; they included hemopericardium, cerebral embolism, perforation of the right atrial wall, air embolism in a coronary artery and hematoma at the arterial perforation site. None of the complications resulted in death. CONCLUSIONS: With experience, radiofrequency catheter ablation of accessory pathways can have an overall success rate of more than 95% and a complication rate of less than 4%. Such rates make this procedure suitable for first-line therapy for patients with Wolff-Parkinson-White syndrome.     

Radiofrequency catheter ablation of atrioventricular junctional ("AV nodal") reentrant tachycardia in patients with implantable cardioverter defibrillators

Catheter ablation of tachycardias has been undertaken successfully in patients with ICDs without damage to the ICD or lead. Ablation of the slow AV nodal pathway, however, is technically challenging because the lead of the ICD lies close to the ablation site. We report successful ablation of AV junctional reentrant tachycardia (AVJRT) in three patients with ICDs. In all cases, the ablation site was within a few millimeters of the ICD lead. The ablation was successful in all cases and did not cause damage to the ICD or lead. The patients have remained free of recurrence of AVJRT during a mean follow-up of 12 months.