Fast pathway ablation in a patient with PR prolongation

The classical form of typical atrioventricular node reentrant tachycardia (AVNRT) is a “slow-fast” pathways tachycardia, and the usual therapy is an ablation of the slow pathway since it carries a low risk of atrioventricular (AV) block. In patients with long PR interval and/or living on the anterograde slow pathway, an alternative technique is required. We report a case of a 42-year-old lady with idiopathic restrictive cardiomyopathy, persistent atrial fibrillation status post pulmonary vein isolation, and premature ventricular complex ablation with a systolic dysfunction, who presented with incessant slow narrow complex tachycardia of 110 bpm that appeared to be an AVNRT. Her baseline EKG revealed a first-degree AV block with a PR of 320 ms. EP study showed no evidence of anterograde fast pathway conduction. Given this fact, the decision was to attempt an ablation of the retrograde fast pathway. The fast pathway was mapped during tachycardia to its usual location into the anteroseptal region, then radiofrequency ablation in this location terminated tachycardia. After ablation, she continued to have her usual anterograde conduction through slow pathway and the tachycardia became uninducible. In special populations with prolonged PR interval or poor anterograde fast pathway conduction, fast pathway ablation is the required ablation for typical AVNRT.     

Inappropriate detection of supraventricular arrhythmias by implantable dual chamber defibrillators: a comparison of four different algorithms

Inappropriate therapy of supraventricular tachyarrhythmias by an ICD is still a common problem. Dual chamber (DDD) ICDs provide additional atrial sensing and should result in higher specificity for detection of supraventricular tachyarrhythmias. However, a direct comparison of different dual chamber algorithms has not been reported. The detection algorithms of four different DDD ICDs were tested: Phylax AV, Defender IV, Ventak AV III DR, and Gem DR 7271. Based on arrhythmias recorded from patients undergoing invasive electrophysiological studies and in many cases of catheter ablation at our institution, a library consisting of 71 supraventricular and 15 ventricular tachyarrhythmias was created. The library consists of episodes of atrial fibrillation, atrial flutter with different AV conduction, typical and atypical AV nodal reentrant tachycardia, AV reentrant tachycardia, sinus tachycardia, and ventricular tachycardia with and without ventriculoatrial conduction. Atrial fibrillation was appropriately classified by all four algorithms. However, the specificity for detection of other supraventricular tachyarrhythmias achieved by the Biotronik (12%) and the Guidant (11%) devices was significantly lower compared to the specificity of the ELA (28%) and the Medtronic DDD ICD (20%). This is due to the fact that the Biotronik and the Guidant algorithm classified all supraventricular tachyarrhythmias resulting in a stable ventricular rate as ventricular tachycardia, whereas the ELA and Medtronic algorithms performed a more detailed analysis by assessment of PR association, atrial onset, or timing of the atrial event relative to the ventricular event, respectively. Atrial fibrillation, the most common supraventricular tachyarrhythmia in patients with ICD, was detected by all devices.     

Catheter Ablation for Recurrent Tachyarrhythmias. Clinical Experience with Two Different Techniques of Ablation in 21 Patients

Between 1984 and 1988, 21 patients underwent catheter ablation for drug refractory arrhythmias. Nine patients presented atrial flutter, atrial fibrillation or atrial tachycardia, nine had supraventricular tachycardia (one AV nodal reentrant tachycardia, one reciprocating tachycardia due to concealed accessory pathway and seven XMPW syndrome). Three had ventricular tachycardia. Fourteen patients were treated with direct current shock ablation (DC) and seven patients with radiofrequency ablation (RF). Eight patients underwent ablation of the His bundle. In six patients permanent AV block could be induced and in two first-degree AV block. All became asymptomatic (two with additional antiarrhythmic drug therapy). In four patients with WPW syndrome DC ablation of the accessory pathway was attempted. In one patient a permanent block in the accessory pathway and in another an intermittent block were obtained. In the two remaining patients with accessory pathways the ablation failed to interrupt the retrograde conduction in one the retrograde conduction was modified: however, in the other no change could be demonstrated. Two patients underwent ventricular foci ablation, with one partial success (arrhythmia controlled with associated drug therapy) and one failure. Three patients had RF His bundle ablation (two for atrial flutter and one for atrial fibrillation). One complete atrioventricular block, one first degree AV block and one first degree AV block associated with right bundle branch block were induced. Recurrence of tachyarrhythmias was prevented only in the patient with complete atrioventricular block. RF ablation of accessory pathway was performed in three patients. It resulted in anterograde block in the accessory pathway in the first patient; a slight modification of the retrograde refractory period in the second and no change was noted in the last one. The first of these three patients could then be controlled with drug therapy. The other two patients underwent surgical dissection of the pathway. One patient underwent an unsuccessful attempt of ventricular focus ablation with RF energy. Complications were more common with DC than with RF ablation but serious ventricular arrhythmias were also observed during RF ablation. Thus, DC ablation was completely successful in eight of 14 patients (57%), partially successful with the addition of drug therapy in three patients (21%) and failed in 22%. HF ablation was successful in only one patient (14.5%) and partially successful in another one (14.5%). This relatively low success rate is due in part to the design of the device and the electrodes used in this study. With technical improvements of RF ablation it seems reasonable to expect that this method will play a significant role in the management of drug refractory arrhythmias, since RF ablation, when compared to DC ablation, has the major advantage not to require general anesthesia during the procedure.     

Automatic Tachycardia Recognition

A microcomputer algorithm for tachycardia identification, suitable for use in un implanted antitachycardia pacemaker, is described. The system employs an atrial and ventricular electrogram, detects a sustained fast rate in either chamber, and awakens the main program to perform detailed analysis of the tachycardia and its immediately preceding beats. The algorithm distinguishes atrial, ventricular, and AV nodal and re-entrant tachycardia from high rates due to sinus tachycardia. For testing of the program, we used a data base of twenty-two tape-recorded and documented arrhythmias provoked during electrophysiologic studies in which atrial and ventricular bipolar electrodes were in place; twenty-one of twenty-two wave successfully detected. These included atrial fibrillation, atrial flutter, atrial tachycardia, AV nodal re-entrant tachycardia, AV re-entrant tachycardia using an accessory pathway, and ventricular tachycardia with and without ventriculo-atrial conduction.     

Efficacy of radiofrequency catheter ablation in treatment of elderly patients with supraventricular tachyarrhythmias and ventricular tachycardia

Radiofrequency catheter ablation was performed in 100 men and 81 women, mean age 78 +/- 5 years, referred for ablation of atrial flutter, supraventricular tachycardia, and ventricular tachycardia, and for ablation of the atrioventricular junction with permanent pacemaker implantation in patients with atrial fibrillation and a rapid ventricular rate not controlled by drug therapy. A hematoma in 1 of 182 ablation procedures (<1%) was the only complication. Radiofrequency catheter ablation was successful in treating 63 of 70 patients (90%) with atrial flutter, in treating 60 of 66 patients (91%) with supraventricular tachycardia, in treating 2 of 2 patients (100%) with ventricular tachycardia, and in ablating the atrioventricular junction in 43 of 44 patients (98%) with atrial fibrillation and a rapid ventricular rate not controlled by drug therapy.     

Tachycardiomyopathy secondary to nonreentrant atrioventricular nodal tachycardia: recovery after slow pathway ablation

Nonreentrant atrioventricular (AV) nodal tachycardia is a rare form of arrhythmia due to simultaneous anterograde conduction in dual AV pathways, one atrial impulse triggering two ventricular complexes. We report the case of a 74-year-old man referred for incessant palpitations resistant to antiarrhythmic medication, and effort dyspnea. A nonreentrant AV nodal tachycardia is diagnosed with electrophysiological study. A dilated cardiomyopathy with left ventricular dysfunction is found with gated blood pool single-photon emission computed tomography. A radiofrequency catheter ablation of the slow pathway is successfully performed. The patient is reassessed 11 months after ablation. He is asymptomatic and left ventricular function has fully recovered.     

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.     

Pacemaker-mediated Tachycardias: A New Modality of Treatment

Three Patients with pacemaker interactive drug resistant tachycardia underwent invasive electrophysiological studies. In the first patient, the retrograde conduction of the artificial reciprocating tachycardia was provided by two right-sided accessory pathways and the antegrade conduction by an atrial synchronous plus generator. In addition, AV nodal tachycardia occurred alternately. In the second patient with intermittent atrial flutter, the AV node and, coincidentally, an AV sequential pulse generator provided high-rate antegrade conduction to the ventricles. In the third patient with surgical complete heart block, intermittent AV-nodal tachycardia induced retrograde atrial activation while an atrial synchronous pacemaker provided the antegrade conduction. Electrode catheter exploration of the heart allowed localization and closed-chest ablation of the accessory pathways or AV node by delivering two to seven 200-Joule direct-current shocks through the appropriate electrode of the exploring catheter, Thereby, pacemaker-mediated arrhythmias could be controlled in these patients in the follow-up of 6 to 8 months.     

Termination of Tachycardias by Transesophageal Electrical Pacing

To evaluate the therapeutic significance of noninvasive transesophageal pacing for termination of tachycardias the method of rapid atrial or ventricular transesophageal pacing was used in 233 patients with different tachycardiac arrhythmias. We were able to terminate atrial flutter in 136 of 162 patients by transesophageal rapid atrial stimulation (conversion to sinus rhythm in 75 cases, induction of atrial fibrillation in 61 cases). Atrial tachycardias were interrupted in 17 of 23 patients (sinus rhythm in 11 cases, atrial fibrillation in six cases). AV reciprocating/AV nodal supravenrricular reentry tachycardias were terminated in 62 of 63 patients (sinus rhythm in 58 cases, atrial fibrillation in four cases). By transesophageal rapid ventricular pacing ventricular tachycardias could be terminated in ten of 15 patients. The success rate of transesophageal pacing was influenced by the pacing rate, by the type of tachycardiac arrhythmia inclusive by the type of atrial flutter and by the tachycardia's cycle length. Because the success rates are comparable with invasive technique and the procedure is simpler, the noninvasive transesophageal antitachycardiac pacing should be respected as the method of the first choice in patients with supraven-tricular tachycardias.     

Long-Term Follow-Up of Patients Treated By Radiofrequency Ablation of the Atrioventricular Junction

JENSEN, S.M., et al .: Long-Term Follow-Up of Patients Treated By Radiofrequency Ablation of the Atrioventricular Junction . Radiofrequency ablation of the AV conduction tissue (His-bundle ablation) is an accepted treatment for therapy resistant atrial fibrillation/flutter. However, data on the long-term effects of the procedure are limited. We followed 50 patients for a mean of 17 months after AV junction ablation. The indication was treatment resistant atrial fibrillation or flutter. The patients underwent a standardized interview performed by two nurses. Health care was studied via the in-patient register. Subjective improvement was reported by 88% and the number of days in hospital per year was reduced from 17 to 7. The use of antiarrhythmic drugs was reduced by 75%. If the reduction in costs of drugs and days in hospital is compared with the cost of the ablation and the pacemaker implantation, breaking even is achieved after 2.6 years. We could not confirm that patients with paroxysmal atrial fibrillation note less improvement than those with chronic fibrillation. Conclusion: Ablation of the AV junction is a cost effective treatment with good long-term results and relatively few complications. Recommendations: Chronic atrial fibrillation: If sinus rhythm cannot be established and in cases in which heart rate regulating drugs have been ineffective, ablation of the AV junction with implantation of a VVIR pacemaker is recommended. Paroxysmal atrial fibrillation: If the patient despite treatment with antiarrhythmic drugs continues to have symptomatic episodes of atrial fibrillation, then AV junction ablation with implantation of a permanent pacemaker is recommended. Patients who have self-limiting episodes of atrial fibrillation should be given a DDDR pacemaker with an automatic mode switch. Patients who do not have self-limiting attacks and require DC conversion, should receive a VVIR pacemaker     

Surgery for Atrial Tachycardia

GUIRAUDON, G.M., ET AL.: Surgery for Atrial Tachycardia. Atrial flutter is associated with a macro-reentrant loop including an area of slow conduction cryoablation of which prevents atrial flutter to occur. Three patients underwent such intervention. Atrial fibrillation is associated with multiple reentrant circuits (leading circle of Allessie) that requires a critical surface area to perpetuate. We have designed an operation, the corridor operation, which isolate the sinus node and the AV node within a small segment of atrial tissue, to restore the chronotropic function of the sinus node. Nine patients underwent the corridor operation at our institution. There were eight men and one woman. Five had incessant atrial fibrillation and four paroxysmal. One patient had associated mitral valve stenosis and one cardiomyopathy. There were no perioperative complications. Six patients had normal sinus node function postoperatively including all the four patients with documented normal sinus node function preoperatively. Three patients required implantation of an AAI pacemaker. Two patients had recurrence of atrial fibrillation within the corridor. Our experience suggests that the corridor operation should be restricted to patients with documented good sinus node function and without structural heart disease. Our experience with five patients with paroxysmal sinus node tachycardia has been disappointing. Only one patient had long-term success although better series have been published.     

The 1998 NASPE prospective catheter ablation registry

The results of the NASPE Prospective Voluntary Registry are reported. A total of 3,357 patients were entered. For those undergoing atrioventricular (AV) junctional ablation (646 patients), the success rate was 97.4% and significant complications occurred in 5 patients. A total of 1,197 patients underwent AV nodal modification for AV nodal reentrant tachycardia, which was successful in 96.1% and the only significant complication was development of AV block (1%). Accessory pathway ablation was performed in 654 patients and was successful in 94%. Major complications included cardiac tamponade (7 patients), acute myocardial infarction (1 patient), femoral artery pseudoaneurysm (1 patient), AV block (1 patient), pneumothorax (1 patient), and pericarditis (2 patients). A total of 447 patients underwent atrial flutter ablation and acute success was achieved in 86% of patients. Significant complications included inadvertent AV block (3 patients), significant tricuspid regurgitation (1 patient), cardiac tamponade (1 patient), and pneumothorax (1 patient). Atrial tachycardia was attempted for 216 patients and the success rate was higher for those with right atrial (80%) or left atrial (72%) compared to those with septal foci (52%). A total of 201 patients underwent ablation for ventricular tachycardia. The success rate was higher for those with idiopathic ventricular tachycardia compared to those with ventricular tachycardia due to ischemic heart disease or cardiomyopathy. While the number of AV junction ablation were higher for those > 60 years of age, there was no significant difference in the success rate or incidence of complication comparing patients > or = 60 to those < 60 years of age. In addition, we found no differences in incidence of success or complications comparing large volume centers (> 100 ablation/year) with lower volume centers or between teaching and non-teaching hospitals.     

Narrow QRS complex tachycardias

Narrow QRS complex tachycardias are either atrioventricular (AV) nodal passive or AV nodal active. AV nodal passive tachycardias do not require the participation of the AV node in maintenance of the tachycardia. Examples are atrial tachycardia, atrial flutter, and atrial fibrillation. Treatment is directed at ventricular rate control with calcium channel blockers or beta-blockers. AV nodal active tachycardias require active participation of the AV node in maintaining the tachycardia. Examples include AV nodal reentry tachycardia and circus movement tachycardia using an accessory pathway. Treatment with a vagal maneuver or adenosine usually terminates the tachycardia. Recognition of these tachycardias is reviewed.     

Complete Atrioventricular Block during Ablation of Atrial Flutter

We report the case of a 51‐year‐old patient who developed a complete atrioventricular (AV) block during the isthmic radiofrequency catheter ablation of a typical atrial flutter. The cause was an acute occlusion of the segment three of the right coronary artery. His recanalization was associated with the immediate restoration of a normal AV conduction. The complication is exceptional (one of 740 consecutive atrial flutter ablations). (PACE 2010; 516–519)     

The effect of ibutilide on retrograde accessory pathway conduction

Ibutilide is a compound with Class III effects marketed for rapid conversion of atrial fibrillation and atrial flutter. The Class III effect is primarily mediated by blockade of the rapid component of the cardiac delayed rectifier of potassium current, Ikr. Ibutilide was used in three patients with concealed accessory pathways during electrophysiological evaluation for ablation of symptomatic atrioventricular reentry tachycardia. Each pathway (mid-septal, left posterior, and left lateral) exhibited a mean retrograde effective refractory period of 240 +/- 20 ms. Each patient had atrioventricular reentry tachycardia that consistently degenerated to recurrent sustained atrial fibrillation. One to two milligrams of intravenous ibutilide converted atrial fibrillation to sinus rhythm and maintained sinus rhythm throughout the procedure. Retrograde accessory pathway conduction was unchanged. Maintenance of sinus rhythm allowed for successful mapping and catheter ablation of the concealed accessory pathways. No direct current cardioversion was needed. In these patients, ibutilide was effective in converting and controlling atrial fibrillation induced by atrioventricular reentry tachycardia without masking retrograde pathway conduction. Antegrade accessory pathway conduction could not be assessed in this study.     

Escape mapping to achieve bidirectional block: A case series

Escape mapping is a novel technique that can be used to locate sites of persistent conduction and achieve exit block during an atrial fibrillation ablation. This method allows for mapping solely with the ablation catheter in the left atrium by annotating to a catheter in the coronary sinus. We illustrate the utility escape mapping during an atrial fibrillation ablation where entrance block is achieved without exit block. We further expand upon this technique by describing the first reported case of escape mapping being used to achieve bidirectional block during an atrial flutter ablation.     

Radiofrequency Catheter Ablation of the Slow Reentrant Pathway of Sustained Ventricular Tachycardia

The article reports the cases of two patients with severe coronary artery disease and associated recurrent sustained ventricular tachycardia successfully treated with radiofrequency catheter ablation. In the first patient, two different types of ventricular tachycardia (one incessant) were eliminated. In all procedures, an area of slow conduction critical for tachycardia maintenance was localized by endocardial mapping techniques. Radiofrequency energy delivered to this area could permanently modify the anatomical substrate of the arrhythmia. After single follow-ups of 19, 14, and 13 months regarding the arrhythmic entities, the patients are well and free from spontaneous recurrences.     

Fast-Slow Type of Atrioventricular Nodal Reentrant Tachycardia: Horizontal Dissociation of the AV Node During Tachycardia

Two patients with recurrent supraventricular tachycardia are presented. The tachycardia was initiated and terminated by atrial extrastimulation beyond the atrial relative refractory period and the atrial activation sequence during the tachycardia was low to high. The induction of tachycardia was dependent on a critical AH interval. In patient 1 who had ventriculoatrial conduction, the tachycardia was initiated by the premature ventricular stimulation followed by double atrial response. In patient 2 the ventriculoatrial conduction was not observed. In both patients, the unchanged atrial cycle length during the tachycardia with antegrade Wenckebach AH block was observed. When AH block occurred during tachycardia the first AH interval was shorter than the subsequent HA interval. In patient 2 verapamil (5 mg) prolonged the atrial cycle length during tachycardia and rapid intravenous injection of adenosine triphosphate (10 mg) terminated the tachycardia. Oral diltiazem (280 mg/day) suppressed the tachycardia in patient 1. These findings suggest that the mechanism of tachycardia may be fast-slow type of AV nodal reentry in the upper portion of the AV node and this type of arrhythmia has tendency to show incessant form.     

Atrial tachycardias following circumferential pulmonary vein ablation: observations during catheter ablation

Circumferential pulmonary vein ablation performing linear lesions around the ostia of the pulmonary veins has been shown to be effective for the treatment of atrial fibrillation. During the follow-up period, persistent atrial tachycardia may occur as a proarrhythmic complication. Only little information is available about the underlying mechanism. In our study, atrial tachycardia following circumferential pulmonary vein ablation was identified in 13 out of 84 consecutive patients (15.5%), as a transient appearance in four and with recurrences for more than 3 months in nine patients (10.7%). Electrophysiological study and ablation was performed in eight cases, revealing common atrial flutter in two, a focal origin secondary to conduction recovery from the pulmonary vein to the left atrium in two and macro reentrant left atrial flutter in four patients. The electrophysiological characteristics demonstrated by electroanatomic activation mapping (CARTO™) and consecutive ablation therapy with a 100% success rate are described and discussed with regard to the literature.     

Dissociation of Atrioventricular Conduction and Refractoriness Following Application of Radiofrequency Energy to the Canine Atrioventricular Node: Acute and Chronic Observations

The electrophysiology of AV nodal modification induced by radiofrequency energy (n = 5) or a sham procedure (n = 5) was studied in ten dogs. The five dogs that received radiofrequency energy had an AH prolongation > 100% from baseline values and this prolongation persisted throughout the 2-month study. The AV nodal functional refractory period was prolonged only acutely. These data indicate a dissociation between the effects on AV nodal conduction and refractoriness that was induced by this procedure. The five sham treated controls showed no acute or chronic electrophysiological changes. In the dogs that received radiofrequency energy, there was fibrosis of the approaches to the AV node and the region of the A V node itself. It is concluded that chronic modification of AV nodal conduction without concomitant changes in refractoriness can be induced by radiofrequency energy delivered in the proximal portion of the AV node. It would be anticipated that this procedure would not decrease the ventricular response to atrial fibrillation or flutter, but may be effective in preventing AV nodal reentrant tachycardia by interfering with conduction either in the AV node or perinodal region. Since the AV node itself suffers at least moderate pathological damage, there may be an appreciable incidence of the late development of complete heart block after this procedure.