Transvenous Catheter Ablation Research Articles

Transvenous cryothermal catheter ablation of re-entry circuit located near the atrioventricular junction in pediatric patients: Efficacy, safety, and midterm follow-up

We investigated the safety and efficacy of cryoablation in the treatment of pediatric patients with accessory pathways (APs) located near the atrioventricular junction and with atrioventricular nodal re-entrant tachycardia (AVNRT). Few studies concern cryoablation in a significant number of pediatric patients involving treatment for supraventricular tachycardias (SVTs) with the reentry circuit located near the atrioventricular junction. Twenty-six pediatric patients (age range: 5 to 20 years) were treated; 14 had AVNRT, 10 had Wolff-Parkinson-White syndrome, and 2 had re-entrant SVT due to a concealed AP. Electrophysiologic study was performed with diagnostic catheters, and cryoablations were performed with a 7-F 4-mm-tip catheter (Freezor, CryoCath Technologies Inc., Kirkland, Canada). Cryomapping, used to identify the tissue site for safe arrhythmia ablation, was performed at -30 degrees C for a maximum of 60 s. Cryoablations were from 4 to 8 min long at -75 degrees C. Acute end points were noninducibility of AVNRT by programmed atrial stimulation at baseline or during isoproterenol performed 30 min after procedure, as well as noninducibility and conduction block over the AP. The chronic end point was arrhythmia recurrence after intervention. No permanent cryo-related complications or adverse outcomes were reported. Twenty-four (92%) patients were acutely successful. During follow-up (range: 1 to 22 months), seven (29%) acutely successful pediatric patients experienced arrhythmia recurrence. Acute results demonstrate cryoablation of SVTs with the reentry circuit located near the atrioventricular junction to be safe and efficacious in pediatric patients. However, the etiology of recurrences reported after intervention need further investigation.

Acute and long-term outcome of transvenous cryoablation of midseptal and parahissian accessory pathways in patients at high risk of atrioventricular block during radiofrequency ablation

The ability of transvenous cryothermal catheter ablation to create reversible lesions (cryomapping) and to avoid catheter dislodgment (cryoadherence) has been shown to be safe and highly effective in elimination of atrioventricular nodal reentrant tachycardia. In addition, cryoablation may be useful in the management of perinodal accessory pathways, but its efficacy and safety in patients at high risk of atrioventricular block during radiofrequency catheter ablation is unknown. This study prospectively evaluated the efficacy and safety of cryoablation in patients with midseptal and parahissian accessory pathways.

Transvenous Cryothermal Catheter Ablation of a Right Anteroseptal Accessory Pathway

In patients with Wolff-Parkinson-White syndrome, right anteroseptal accessory pathways are uncommon and run from the atrium to the ventricle in close anatomic proximity to the normal AV conduction system. Radiofrequency catheter ablation is the first-line therapy for elimination of these accessory pathways. Although the initial success rate is high, there is a potential risk of inadvertent development of complete heart block, and the recurrence rate is relatively high. The capability of cryothermal energy to create reversible lesions (ice mapping) at less severe temperatures provides a potential benefit in ablation of pathways located in a complex anatomic area, such as the mid-septum and anteroseptum.

Nursing grand rounds

Wolff-Parkinson-White (WPW) syndrome involves connections of myocardial fibers between the atrium and ventricle that can carry electrical impulses outside of the normal conduction system. Treatment options include pharmacologic management, surgical interruption, antitachycardia devices, or transvenous catheter ablation. This is a case study of a patient who underwent surgical ablation of an accessory pathway and reoperation because of continued abnormal conduction. She had tachypalpitations after both procedures and later underwent radiofrequency ablation. Nursing care was complicated because she spoke very little English and was extremely anxious about her illness.

Catheter ablation using radiofrequency energy

Recently, transvenous catheter ablation using radiofrequency impulses has been applied in experimental animals as well as in humans. This review describes the biophysics, mechanisms, and tissue effects of radiofrequency alternating current. Ablation of the AV-junction has been performed in experimental studies as well as in a growing number of patients. Complete AV-block or modification of the AV conduction by RF-current application can be achieved in about 45-65% of patients. Presently about 50% of patients with rightsided accessory pathways can be successfully managed using radiofrequency impulses. Certain limitations exist using a biopolar "epi-endocardial" electrode configuration for leftsided accessory pathways. Only few studies are available concerning the use of RF ablation of ventricular tachycardia foci. As most experimental investigations were carried out in structurally nondiseased myocardium, the use of this new technique in fibrotic or scarred tissue warrants further studies. Radiofrequency catheter ablation seems to be feasible and relatively safe for the treatment of otherwise drug-refractory supraventricular arrhythmias; further studies are needed to assess the safety and efficacy in patients with drug-refractory ventricular tachyarrhythmias.

Long term efficacy of transvenous catheter ablation of the atrioventricular junction for refractory supraventricular tachycardia.

Twenty-four patients who underwent transvenous catheter ablation of the atrioventricular (A-V) junction between November 1982 and February 1987 were followed from 18-72 months (mean 47.9) to assess the long term efficacy and safety of the procedure. All had severely symptomatic supraventricular tachyarrhythmias refractory to standard treatment. Atrioventricular conduction was abolished in 23 patients, 22 having permanent pacemakers implanted. Conduction has recovered, though it is modified, in one patient who is asymptomatic on digoxin. Four patients have died; one suddenly 20 months following the procedure, one of progressive heart and liver failure due to hemochromatosis, and two of a stroke. Four patients have had complications related to permanent pacing; one patient has required generator replacement and one patient ventricular lead replacement, one patient had asystole and one patient had a pacemaker-related tachycardia. Two patients remain symptomatic but improved by the procedure. Seventeen patients are free of their original symptoms, 11 having no intervening morbid events. These results demonstrate that patients with severely symptomatic supraventricular tachyarrhythmias may gain long term symptomatic relief from the procedure, but permanent pacing is a cause of significant morbidity and there is a small incidence of late sudden cardiac death.

Electrical ablation of junctional tachycardias showing a long RP interval.

Transvenous catheter ablation of the anomalous pathway was attempted in seven patients with drug-resistant repetitive long RP tachycardias. The patients were aged 5.5-65 years (median 20 years) and had received from four to seven antiarrhythmic agents without effect. Electrophysiological studies confirmed the anomalous substrate for tachycardia in five patients but in two patients an intranodal mechanism could not be excluded. Discharges were delivered to the coronary sinus ostium or low right atrium close to the ostium using conventional defibrillators (three patients) or a modified device (four patients). Transient AV block was seen after six attempts progressing to permanent block in one patient. In no patient could enduring block in the retrograde limb of tachycardia be achieved, and tachycardia recurred in all patients in whom anterograde conduction remained intact. The failure of selective ablation techniques in long RP tachycardia may reflect the diversity of substrate anatomy or particular properties (anatomical or functional) of the pathway compared with the usual types of anomalous pathway.

Bundle Branch Reentrant Tachycardia Treated by Transvenous Catheter Ablation of the Right Bundle Branch

Recurrent episodes of ventricular tachycardia not responding to medical treatment occurred in a 56-year-old man. Electrophysiological investigation showed ventricular tachycardia due to bundle branch reentry. Using a method similar to catheter ablation of the atrioventricular junction, ablation of the right bundle branch was performed by an electrical shock of 250 joules. While before the ablation ventricular tachycardia occurred several times a day and its induction by programmed ventricular stimulation was facilitated by the administration of antiarrhythmic drugs, no initiation of ventricular tachycardia was possible after ablation of the right bundle branch. Over a follow-up of 30 months the patient has not suffered from tachycardia and the right bundle branch block persists.

Short‐ and long‐term results of transvenous catheter ablation of the atrioventricular conduction system

Twenty-two patients with refractory supraventricular arrhythmias were treated by catheter-delivered high-energy shocks to the atrioventricular conduction system. All patients had a minimum follow-up period of six months (mean +/- SD, 15 +/- 9 months), at which time 21 of the 22 patients were free of symptoms and required no antiarrhythmic therapy. Permanent pacemakers were implanted in all patients. These results show that transvenous ablation or modification of atrioventricular conduction is a safe and effective technique to treat a wide range of supraventricular arrhythmias, and obviates the need for open-heart surgery for the interruption of atrioventricular nodal conduction.

Transvenous catheter ablation of extranodal accessory pathways

Twelve patients with an accessory pathway and recurrent symptomatic reciprocating tachycardia or atrial fibrillation, or both, underwent attempted transvenous catheter ablation of the accessory pathway. In one patient with a small right coronary artery, the pathway was along the right free wall. In 11 patients, the pathway was located at or within 15 mm of the coronary sinus os. For these patients, a quadripolar electrode catheter was placed in the coronary sinus and positioned, if possible, so that the proximal pair of electrodes straddled the pathway. For those patients with a pathway > 5 mm within the coronary sinus, the most proximal electrode was placed at the os. This proximal pair of electrodes was connected to the cathodal output of a defibrillator with an anterior chest wall patch serving as the current sink. Two shocks were then delivered for a cumulative energy of 500 to 600 J (stored energy).Among the eight patients with a pathway at or within 5 mm of the coronary sinus os, conduction over the pathway was abolished in five and modified in one. Among the four patients with a pathway farther from the os (10 to 15 mm) and along the right free wall, pathway conduction was modified only in two. Rupture of the coronary sinus did not occur in any patient. There were no serious complications. Minor damage surrounding the area of ablation was seen at the time of surgical division of the accessory pathway in two of five patients with unsuccessful ablation who subsequently underwent surgery.Transvenous catheter ablation of accessory pathways appears to be a safe and reasonably effective alternative to surgery for those patients with a pathway at or near the coronary sinus os, but not for those with a pathway farther from the septum. Although subsequent intraoperative mapping was more difficult because of the loss of large, discrete atrial electrograms, surgical division was successful in all five patients after unsuccessful catheter ablation.

Modulation of atrioventricular nodal conduction using radiofrequency current

Transvenous catheter ablation of the atrioventricular (AV) node has become a new therapeutic alternative in the treatment of patients with drug-resistant supraventricular tachycardia. After high-energy direct current shocks are delivered to the AV junction, conducd tion block is achieved in about 80% of patients, with subsequent control of symptoms. Pacemaker implantation, however, is mandatory because no, or only slow, junctional or ventricular escape rhythms emerge after ab1ation.l Therapeutic means currently under investigation for the modification of AV nodal conduction are transcatheter application of radiofrequency current 2 or laser energy. 3 We report the successful modulation of AV nodal conduction by radiofrequency current in a patient with intermittent, medically refractory atrial fibrillation.

Bundle branch reentrant tachycardia treated by transvenous catheter ablation of the right bundle branch

Bundle branch reentrant tachycardia treated by transvenous catheter ablation of the right bundle branch

High frequency alternating current ablation of an accessory pathway in humans

High frequency alternating current ablation of an accessory pathway was performed in a patient with incessant circus movement tachycardia using a right-sided, free wall accessory pathway. Antiarrhythmic drugs, antitachycardia pacing and transvenous catheter ablation using high energy direct current shocks could not control the supraventricular tachycardia. A 7F bipolar electrode catheter with an interelectrode distance of 1.2 cm was positioned at the site of earliest retrograde activation during circus movement tachycardia. At this area, two alternating current high frequency impulses were delivered with an energy output of 50 W through the distal tip of the bipolar catheter, while the patient was awake. After the first shock supraventricular tachycardia terminated and accessory pathway conduction was absent without altering anterograde conduction in the normal atrioventricular (AV) conduction system. No reports of pain or other complications were noted. In short-term follow-up of 5 months, the patient had been free of arrhythmias without antiarrhythmic medication. Thus, high frequency alternating current ablation was performed for the first time in the treatment of an arrhythmia incorporating an accessory pathway in a human. This technique may be an attractive alternative to the available transcatheter ablation techniques and to antitachycardia surgery.

Ectopic atrial tachycardia after transvenous catheter ablation of a posteroseptal accessory pathway

Closed chest electrode catheter ablation of a posteroseptal accessory pathway was performed on an 18 year old patient with recurrent supraventricular tachycardia. After the procedure, ectopic atrial tachycardia was observed for the first time. Detailed endocardial atrial mapping revealed that this ectopic atrial tachycardia originated from the first site of catheter ablation. As retrograde conduction resumed, a second ablation procedure was performed, resulting in successful ablation of both the ectopic atrial tachycardia and the accessory pathway conduction.

Transvenous catheter ablation of the His bundle in ventricular tachycardia

The usefulness of transvenous catheter ablation of the His bundle in three patients with recurrent ventricular tachycardia (VT), in which the initiating mechanism was recognized during a rapid atrial rhythm, is reported. Tachycardia was refractory to conventional treatment and required transthoracic direct-current shocks in all patients. In patient No. 1 double tachycardia (atrial flutter and VT) was documented and VT was easily induced by rapid atrial pacing. In patients Nos. 2 and 3 initiation of VT during junctional reciprocating and atrial tachycardia, respectively, was observed. Interruption of the His bundle was performed by means of fulguration. Stable atrioventricular (AV) block was observed in patient No. 1 after the ablative procedure; patient No. 2 showed anterograde conduction over a posterior septal accessory pathway with no evidence of conduction over the normal conduction system in both the anterograde and retrograde directions. In patient No. 3, transient AV block was observed; AV conduction resumed 2 days later and the cardiac rhythm showed persistent ectopic atrial tachycardia with second-degree AV block. Patients Nos. 1 and 2 underwent pacemaker implantation, but patient No. 2 was not pacemaker dependent. After the procedure, VT no longer occurred in any of the patients (follow-up: 2 years, 5 months, and 6 months).

Right atrial thrombus formation after transvenous catheter ablation of the atrioventricular node

The formation of a right atrial mass was detected in a patient by two-dimensional echocardiography 3 weeks after successful transvenous electrical ablation of the atrioventricular node had been performed. The mass was attached to the atrial septum at the site where the electrode catheter used for the ablation had supposedly been located and it exhibited no mobility. It was interpreted as a right atrial thrombus induced by the ablation procedure. Although no pulmonary embolic events have been observed during a 7 month follow-up period, right atrial thromboembolism must be considered a potentially dangerous complication of transvenous catheter ablation to control cardiac arrhythmias.

Cryosurgical ablation of atrioventricular junction without extracorporeal circulation

A closed technique, using thoracotomy without cardiopulmonary bypass and atriotomy, for cryosurgical ablation of the atrioventricular node-His bundle junction is described. The technique was used in 34 patients selected from among 136 patients with disabling supraventricular tachyarrhythmias refractory to drug therapy in whom atrioventricular block was produced. After thoracotomy, four methods can be used to determine the site of cryoinstrument application: palpation of the internal anatomic landmarks, a "mechanical test," use of a cryoprobe, or recording of the His bundle electrogram. The cryoprocedure lasts 160 to 180 seconds at temperatures of -60 degrees to -80 degrees C and is repeated once or twice. Complete atrioventricular block was induced in 29 of the 34 patients. Paroxysmal tachycardia was terminated in 31. There were no operative deaths. The frequency of surgical complications was nearly three times lower than in the group of 77 patients subjected to open cryodestruction of the atrioventricular junction, and the length of hospital stay after the operation was an average of 4.7 days shorter. The follow-up for up to 6.5 years (mean 34 months) failed to show postoperative paroxysmal tachycardia or tachyarrhythmia in 31 patients. In my opinion, this rather safe method for ablation of the atrioventricular junction could be more widely used, especially if there are contraindications for extracorporeal circulation or if transvenous catheter ablation has failed.

Transvenous catheter ablation of the accessory atrioventricular pathway in the permanent form of junctional reciprocating tachycardia

delivered.4 The myocardial necrosis that resulted from the administration of multiple endocardial shocks in our patient may have contributed to the development of left-heart failure that occurred a few days after the shocks. Further studies are required to evaluate the hemodynamic effects of endocardial shocks in humans. However, caution should prevail with this experimental procedure of treatment in patients with severely impaired ventricular function. Cardiology of Soroka Hospital (Beer Sheva) for referring this patient to us. X References

Transvenous catheter ablation of a right atrial automatic ectopic tachycardia

A 10 year old patient with right atrial automatic ectopic tachycardia underwent successful transvenous catheter ablation after endocardial mapping. Tachycardia had been present for 7 years before ablation and associated with development of dilated cardiomyopathy. A single 50 J discharge at the point of earliest atrial activation was followed by the establishment of sinus rhythm that remains at 10 months' follow-up. This case represents the first reported successful catheter ablation of an atrial automatic ectopic tachycardia. Specific anatomic factors favoring successful ablation and improvement in technique are discussed.

Transvenous catheter ablation of the atrioventricular conduction system for treatment of refractory supraventricular tachycardia: Electrophysiologic and pathologic observations in dogs

Transvenous catheter ablation of the atrioventricular conduction system for treatment of refractory supraventricular tachycardia: Electrophysiologic and pathologic observations in dogs