Transvenous Catheter Ablation Research Articles

Transvenous Radiofrequency Catheter Ablation for an Aldosterone-Producing Tumor of the Left Adrenal Gland: A First in Human Case Report

PurposeTo describe a novel technique of transvenous radiofrequency catheter ablation of an aldosterone-producing adenoma (APA) of the left adrenal gland using the GOS System (Japan Lifeline, Tokyo, Japan). Using the GOS system, a flexible radiofrequency tip catheter can be inserted into the adrenal central and tributary veins, the drainers for functional tumors.Materials and methodsAn APA at the left adrenal gland, which was diagnosed by segmental adrenal venous sampling following administration of 0.25 mg cosyntropin, was ablated using the GOS catheter inserted into adrenal tributary veins via a right femoral vein 7-Fr sheath. The effect of radiofrequency ablation on APA was assessed using the international consensus on surgical outcomes for unilateral primary aldosteronism (PA).ResultsNo device-related complications were observed. The patient was deeply sedated under blood pressure and heart rate control with continuous administration of β-blockers. Then, the tumor and surrounding adrenal gland were cauterized at 7000 J two times each in sequence. The output time was 7−11 min for each ablation and 80 min in total. For blood pressure and pulse rate control, esmolol hydrochloride and phentolamine mesylate were used. The contrast enhancement of APA disappeared on dynamic CT immediately after the procedure. PA was biochemically cured until 12 months after the procedure.ConclusionUsing the radiofrequency device with the GOS catheter and system is a method for cauterizing adrenal tumors from blood vessels. This approach resulted in a marked reduction in aldosterone concentrations and a complete biochemical cure of PA over the observation period.Graphical

Selective intracardiac sympathetic denervation acutely modulates left ventricular control

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Centre for Cardiovascular Research (DZHK) Background The sympathetic nervous system plays an integral role in cardiac physiology. Neuromodulation is emerging as a treatment option for ventricular arrhythmias, but selective intracardiac approaches are rare. Sympathetic nerve fibers innervating the left ventricle have been demonstrated to be amenable to transvenous catheter stimulation along the coronary sinus (CS). Purpose The aim of the present study was to modulate left ventricular control by selective sympathetic denervation using epicardial or standard catheter ablation for intracardiac axotomy at the level of the CS. Methods First, the impact of epicardial CS ablation on cardiac electrophysiology was studied in a Langendorff model of murine hearts (n=10 each, ablation and control). Second, the impact of transvenous, anatomically-driven axotomy by catheter-based radiofrequency ablation along the CS was evaluated in a healthy ovine in vivo model (n=8) before and during left stellate ganglion stimulation (LSGS). Results CS ablation for intracardiac sympathetic axotomy prolonged epicardial ventricular refractory period (VRP) without (41.8±8.4 ms vs. 53.0±13.5 ms; P=0.0487) and with beta1-2-adrenergic receptor blockade (47.8±2.8 ms vs. 73.1±5.0 ms; P=0.0009) and enhanced the increasing effect of beta1-2-adrenergic receptor blockade on epicardial VRP (∆VRP 6.3±7.0 ms vs. 20.0±7.5 ms; P=0.0045) in mice (Figure, A). Mean epicardial wave propagation velocity in the left ventricle was faster in ablated hearts than in controls (1.13±0.05 m/s vs. 1.00±0.02 m/s; P=0.0463), but did not differ in the right ventricle (1.15±0.05 m/s vs. 1.20±0.08 m/s; P=0.7938). Transvenous catheter ablation of the CS reduced systolic (SBP, 57.7±5.0 mmHg vs. 46.9±3.6 mmHg; P=0.0428) and diastolic blood pressure (DBP, 35.5±3.0 mmHg vs. 26.7±1.8 mmHg; P=0.0106) and diminished the blood pressure increase during LSGS in sheep (∆SBP 21.9±3.8 mmHg vs. 10.5±4.2 mmHg; P=0.0234; ∆DBP 9.0±1.9 mmHg vs. 3.0±1.2 mmHg; P=0.0391) (Figure, B, C). Cycle length remained unchanged by LSGS, both before (baseline 653.2±20.6 ms vs. LSGS 627.8±27.5 ms; P=0.2309) and after CS ablation (baseline 734.8±24.2 ms vs. LSGS 746.2±37.3 ms; P=0.7145). Conclusions Anatomically-driven axotomy targeting nerve fibers along the CS enables selective intracardiac sympathetic denervation resulting in acute modulation of left ventricular control.

Hybrid thoracoscopic surgical and transvenous catheter ablation versus transvenous catheter ablation in persistent and longstanding persistent atrial fibrillation (HARTCAP-AF): study protocol for a randomized trial

BackgroundSuccess rates with conventional transvenous endocardial pulmonary vein isolation in patients with persistent and longstanding persistent atrial fibrillation (AF) are variable due to advanced electrical and structural remodeling of the atria. As a consequence, more extensive endocardial lesions, minimally invasive thoracoscopic surgical techniques, and hybrid ablation (combining thoracoscopic epicardial surgical and endocardial catheter ablation) have been developed.HypothesisThe HARTCAP-AF trial hypothesizes that hybrid AF ablation is more effective than (repeated) transvenous endocardial catheter ablation in (longstanding) persistent AF, without increasing the number of associated major adverse events.MethodsThis randomized controlled trial will include 40 patients with persistent or longstanding persistent AF who will be 1:1 randomized to either hybrid ablation or (repeated) catheter ablation. The procedures and follow-up are conducted according to the guidelines. The primary effectiveness endpoint is freedom from any supraventricular arrhythmia lasting longer than 5 min without the use of Vaughan-Williams class I or III antiarrhythmic drugs through 12 months of follow-up after the last procedure. In the catheter ablation arm, a second procedure planned within 6 months after the index procedure is allowed for obtaining the primary endpoint. Additionally, adverse events, cost-effectiveness, and quality of life data will be recorded.Trial registrationClinicalTrials.gov, NCT02441738. Registered on 12 May 2015.

Subxiphoid Minimally Invasive Epicardial Ablation (Convergent Procedure) With Left Thoracoscopic Closure of the Left Atrial Appendage

The Convergent Procedure is a combined epicardial and endocardial ablation performed by a cardiac surgeon and electrophysiologist to treat symptomatic persistent and long standing persistent atrial fibrillation. The epicardial ablation is performed on the entire width of the posterior left atrial wall using monopolar radiofrequency via a subxiphoid incision. There is no sternotomy and cardiopulmonary bypass is not utilized. The surgical ablation is then followed by endocardial voltage mapping and ablation, allowing for complete lesion set creation. Left atrial appendage exclusion can be performed via left thoracoscopic approach at the same time as the surgical ablation. The Convergent Procedure is a truly hybrid, collaborative procedure which combines the strengths of minimally invasive cardiac surgery and percutaneous electrophysiologic techniques to treat a challenging disease process.

Pericardial adhesions as a consequence of cryoballoon ablation detected during the hybrid AF ablation procedure

Pericardial adhesions as a consequence of cryoballoon ablation detected during the hybrid AF ablation procedure

Epilepsy: Novel transvenous catheter mapping and ablation could supersede invasive antiepileptic surgery.

Epilepsy: Novel transvenous catheter mapping and ablation could supersede invasive antiepileptic surgery

Direct visualization of pulmonary vein stenosis after previous catheter ablation

A 63-year-old man with a 16-year history of persistent atrial fibrillation (AF) and hypertension underwent pulmonary vein (PV) isolation by radiofrequency (RF) catheter ablation 6 years ago. Because of recurrent symptomatic AF, dilated left atrium, and subsequent failure of antiarrhythmic drugs, he underwent a hybrid ablation procedure using video-assisted thoracoscopic epicardial bipolar RF ablation and endocardial check of the lesions. 1 Pison L. La Meir M. van Opstal J. Blaauw Y. Maessen J. Crijns H.J. Hybrid thoracoscopic surgical and transvenous catheter ablation of atrial fibrillation. J Am Coll Cardiol. 2012; 60: 54-61 Abstract Full Text Full Text PDF PubMed Scopus (180) Google Scholar

Hybrid thoracoscopic and transvenous catheter ablation of atrial fibrillation

The hybrid approach combines an epicardial ablation with a percutaneous endocardial ablation in a single-step or sequential procedure. This study provides an overview of the hybrid procedure for the treatment of stand-alone atrial fibrillation (AF). Papers selected for this review were identified on PubMed and the final selection included nine studies. The total number of patients was 335 (range 15-101). Mean age ranged from 55.2 to 62.9 years. The hybrid approach achieved satisfactory results, with AF-antiarrhythmic drug-free success rates higher than those in isolated procedures. In particular, the bilateral approach with a bipolar device showed a high success rate independently of the AF type and seems to be the better choice for the hybrid procedure. Despite good preliminary results, large, multicentre trials of hybrid AF ablation that target a population of patients with long-standing persistent disease are necessary to establish whether this approach may represent, in the future, a gold-standard treatment for AF.

Invited Commentary

Invited Commentary

Hybrid Thoracoscopic Surgical and Transvenous Catheter Ablation of Atrial Fibrillation

The purpose of this study was to evaluate the feasibility, safety, and clinical outcomes up to 1 year in patients undergoing combined simultaneous thoracoscopic surgical and transvenous catheter atrial fibrillation (AF) ablation. The combination of the transvenous endocardial approach with the thoracoscopic epicardial approach in a single AF ablation procedure overcomes the limitations of both techniques and should result in better outcomes. A cohort of 26 consecutive patients with AF who underwent hybrid thoracoscopic surgical and transvenous catheter ablation were followed, with follow-up of up to 1 year. Twenty-six patients (42% with persistent AF) underwent successful hybrid procedures. There were no complications. The mean follow-up period was 470 ± 154 days. In 23% of the patients, the epicardial lesions were not transmural, and endocardial touch-up was necessary. One-year success, defined according to the Heart Rhythm Society, European Heart Rhythm Association, and European Cardiac Arrhythmia Society consensus statement for the catheter and surgical ablation of AF, was 93% for patients with paroxysmal AF and 90% for patients with persistent AF. Two patients underwent catheter ablation for recurrent AF or left atrial flutter after the hybrid procedure. A combined transvenous endocardial and thoracoscopic epicardial ablation procedure for AF is feasible and safe, with a single-procedure success rate of 83% at 1 year.

Cell-specific nanoplatform-enabled photodynamic therapy for cardiac cells

Over the last decades, various cardiac ablation technologies and procedures have been developed for patients with drug-resistant cardiac arrhythmias. It is now widely accepted that in selected patient populations, catheter ablation is an advantageous alternative to lifelong pharmacologic treatment. 1 Oral H. Scharf C. Chugh A. et al. Catheter ablation for paroxysmal atrial fibrillation. Circulation. 2003; 108: 2355-2360 Crossref PubMed Scopus (790) Google Scholar , 2 Morady F. Sgheinman M.M. Transvenous catheter ablation of a posteroseptal accessory pathway in a patient with the Wolff–Parkinson–White syndrome. N Engl J Med. 1984; 310: 705-707 Crossref PubMed Scopus (104) Google Scholar , 3 Calkins H. Brugada J. Packer D.L. et al. HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for personnel, policy, procedures and follow-up A report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation developed in partnership with the European Heart Rhythm Association (EHRA) and the European Cardiac Arrhythmia Society (ECAS); in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), and the Society of Thoracic Surgeons (STS). Endorsed and approved by the governing bodies of the American College of Cardiology, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, and the Heart Rhythm Society. Europace. 2007; 9: 335-379 Crossref PubMed Scopus (558) Google Scholar Ablation consists of delivering physical energy locally to specific myocardial regions to abolish arrhythmogenic tissue. Regardless of the energy employed, be it radiofrequency energy, cryoenergy, light amplification by stimulated emission of radiation (LASER), or ultrasound, ablation techniques are limited by the nonspecific nature of the resultant cellular damage. Myocytes perpetuating the arrhythmia experience similar damage to that of bystander cells, such as fibroblasts, adipocytes, or neurons. This can result in complications such as atrioesophageal fistula, pulmonary veins stenosis, or coronary artery injury. 4 Castaño A. Crawford T. Yamazaki M. Avula U.M.R. Kalifa J. Coronary artery pathophysiology after radiofrequency catheter ablation: review and perspectives. Heart Rhythm. 2011; 8: 1975-1980 Abstract Full Text Full Text PDF PubMed Scopus (35) Google Scholar , 5 Cappato R. Calkins H. Chen S.A. et al. Worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circulation. 2005; 111: 1100-1105 Crossref PubMed Scopus (1246) Google Scholar , 6 Pappone C. Oral H. Santinelli V. et al. Atrio-esophageal fistula as a complication of percutaneous transcatheter ablation of atrial fibrillation. Circulation. 2004; 109: 2724-2726 Crossref PubMed Scopus (759) Google Scholar , 7 Sosa E. Scanavacca M. Left atrial-esophageal fistula complicating radiofrequency catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol. 2005; 16: 249-250 Crossref PubMed Scopus (26) Google Scholar , 8 Robbins I.M. Colvin E.V. Doyle T.P. et al. Pulmonary vein stenosis after catheter ablation of atrial fibrillation. Circulation. 1998; 98: 1769-1775 Crossref PubMed Scopus (405) Google Scholar In addition, the lack of cellular discrimination increases the required energy for ablation and can prolong procedure times.

Surgical Treatment for Isolated Atrial Fibrillation Minimally Invasive vs Classic Cut and Sew Maze

We sought to compare outcomes after two surgical approaches for the treatment of atrial fibrillation (AF): a minimally invasive, staged hybrid approach combining surgery with catheter ablation, [Hybrid Maze (HM)] and the classic cut and sew Maze (CM). From April 2004 to March 2010, 63 stand-alone AF procedures were performed by two surgeons at a single center and followed up for ≥6 months. CM was offered to all patients. After July 2007, patients were also prospectively offered a two-stage HM: stage 1 = a beating heart bipolar radiofrequency pulmonary vein isolation and left atrial appendage ligation; stage 2 = transvenous catheter ablation connecting the pulmonary veins to each other and the mitral annulus when AF was present after stage 1. Outcomes were compared between 25 HM and 38 CM using χ or Fisher exact test analysis. Postoperatively, there was no difference in 30-day mortality (0%), complications (4% HM vs. 18% CM), or median length of stay (5 days). At last follow-up, 88% of HM and 95% of CM were free from AF; 80% of HM and 90% of CM were free from AF and antiarrhythmic medication (P ≥ 0.3). Twenty-nine percent of HM required a subsequent catheter ablation (stage 2) when compared with 8% of the CM patients (P = 0.04). Freedom from AF and antiarrhythmic medication at 1 year was 52% for the HM and 87.5% for the CM (P = 0.004). In AF patients reluctant to undergo a CM but willing to undergo subsequent catheter ablation, a minimally invasive approach is a reasonable strategy. Because pulmonary vein isolation alone may be sufficient in two-thirds of patients and delayed reconnection is common, an interval two-stage hybrid approach may prove preferable over a one-stage combined hybrid approach; however, successful sinus restoration may take longer with this approach.

Energy Sources for Ablation in the Pericardial Space.

Catheter ablation has been widely used for the management of cardiac arrhythmias. Transvenous endocardial catheter ablation successfully eliminates or modifies the critical substrate for most arrhythmias. Most arrhythmias can be eliminated with conventional endocardial mapping and radiofrequency energy delivery, but some critical arrhythmic substrates are not accessible via endocardial access and this has led to epicardial mapping and ablation in addition to traditional endocardial mapping techniques. This article reviews current approaches to epicardial ablation and discusses the specialized tools that increase ablation efficacy and safety.

4:2:1 – a thoracic vein tachycardia

A 27-year old woman presented to the Foothills Medical Centre (Calgary, Alberta) with a two-year history of intermittent episodes of rapid heart action. There was no history of cardiovascular disease, and a transthoracic echocardiogram revealed no evidence of structural heart disease. She underwent a four-catheter transvenous electrophysiological study and catheter ablation procedure for recurrent atrial tachycardia. On the day of the procedure, a 12-lead surface electrocardiographic recording (Figure 1) documented clinical tachycardia. Intracardiac recordings from the superior vena cava (SVC), right atrium and surface electrocardiographic leads II and V1 at 100 mm/s paper speed (Figure 2) were recorded during activation mapping. The recording from the SVC revealed that structure was the origin of the arrhythmia, whereby the tachycardia exhibited a rate of 460 beats/min. Every other beat of the tachycardia conducted to the atria, and every other atrial depolarization (230 beats/min) conducted to the ventricles, resulting in an overall conduction ratio of 4:2:1 and a ventricular rate of 115 beats/min. Figure 1) A surface 12-lead electrocardiogram during atrial tachycardia Figure 2) Intracardiac recordings from the superior vena cava (SVC), right atrium (RA) (P wave), and surface leads II and V1 (QRS) during atrial tachycardia (paper speed was 100 mm/s) Because conduction to the atria occurred in a regular 2:1 fashion, the tachycardia manifested electrocardiographically as an atrial tachycardia. However, one can understand how more rapid or variable conduction can produce less organized atrial activation, or atrial fibrillation. The arrhythmogenic potential of the pulmonary veins is well recognized (1), but all thoracic veins can, in fact, be arrhythmogenic, including the SVC, as demonstrated in the present case (2–4). The SVC was electrically isolated, and the patient had no symptoms after one month of follow-up.

Acute and long-term outcome of transvenous cryothermal catheter ablation of supraventricular arrhythmias involving the perinodal region

Cryoenergy is a new valuable treatment option to perform ablation close to the atrioventricular (AV) node in the cure of supraventricular tachycardias because of its favourable properties, such as the possibility of creating reversible lesions. The aim of this study was to report our experience on the effectiveness and safety of catheter cryoablation performed in "critical areas" to treat a large cohort of patients with supraventricular arrhythmias. One hundred and thirty-one patients suffering from supraventricular tachycardias underwent catheter cryoablation using a 7F catheter. Eighty-seven patients presented with AV nodal re-entrant tachycardia (AVNRT), 39 had accessory pathways (APs) either manifest or concealed (15 midseptal, 24 parahissian), three had ectopic right atrial tachycardia (AT), and two patients had a permanent junctional reciprocating tachycardia (PJRT). When the optimal parameters were recorded, ice mapping at -30 degrees C was performed for 80 s to validate the ablation site. If the expected result occurred, cryoablation was carried out by lowering the temperature to -75 degrees C for 4 min. In two patients cryoablation was not performed because of technical reasons. Cryoablation was acutely successful in 84 out of 85 patients with AVNRT, in 37 of 39 with APs and in all patients with AT and PJRT. No complications occurred in any patient. Transient AV conduction impairment occurred in seven patients with midseptal APs and in two patients with AVNRT. In particular, in these patients no late permanent AV block was observed at follow-up. At a mean follow-up of 27 +/- 12.9 months, clinical success rate was 87%. Cryoablation is a safe and effective technique with a high success rate in the long term. It may be particularly useful when performing ablation close to the AV node or His bundle owing to the possibility of validating the ablation site with ice mapping, which creates only a reversible lesion, mainly in the midseptal APs.

Transvenous Radiofrequency Catheter Ablation for Atrial Flutter and Atrial Fibrillation

Now this is not the end. It is not even the beginning of the end, but it is, perhaps the end of the beginning. —Winston Churchill, November 10, 1942 Transvenous radiofrequency catheter ablation (RFA) for treatment of atrioventricular (AV) reentrant tachycardia and AV nodal reentrant tachycardia is remarkably successful. To the best of my knowledge, there has not been a large randomized trial comparing RFA with other treatments for these tachycardias. The lack of such trials is due at least in part to the self-evident efficacy of RFA in this setting. In turn, the efficacy of RFA for these tachycardias is in large part due to the fact that the anatomy and pathophysiology of these two tachycardias are well understood. The success of RFA for treating AV reentrant tachycardia and AV nodal reentrant tachycardia has quite rightly led to a large effort to expand this success, and thereby the indications for RFA, to other tachyarrhythmias. Article p 1676 Among the supraventricular tachyarrhythmias, the atrial flutter (AFL)/atrial fibrillation (AF) family is an obvious but challenging target for RFA. The early results are promising. AF is numerically the largest member of this family of tachyarrhythmias. The other family members are atrial tachycardia and AFL. These tachyarrhythmias can be closely related anatomically, can share a common pathophysiology, and can be found in the same patient.1 There are probably several different anatomies and pathophysiologies for these tachyarrhythmias. Inability to fully understand the anatomy and pathophysiology of a tachyarrhythmia in an individual patient makes RFA more difficult and to some extent empiric. Among the various AFLs, one is well understood. So-called classic, typical, common, or isthmus AFL has a characteristic but not unique surface ECG pattern: a “saw-tooth” pattern of p waves in the inferior leads (II, III, and aVF). It is a reentrant …

Image Integration Guided Catheter Ablation of Arrhythmias

Transvenous catheter ablation has become a curative treatment for many arrhythmias. Knowing the precise catheter location in relation to true cardiac anatomy will benefit catheter ablation procedures. A novel electroanatomic mapping system (CartoMerge™, Biosense Webster) with the capability of integrating pre-procedural computed tomography (CT) or magnetic resonance (MR) images with electroanatomic maps has been recently approved for patient care.

Direct imaging of transvenous radiofrequency cardiac ablation using a steerable fiberoptic infrared endoscope

Direct imaging through blood has been achieved in vivo using fiberoptics and infrared wavelength technology. The purpose of this study was to determine the feasibility of using a percutaneous, steerable, fiberoptic infrared endoscope to identify and characterize the electrode-tissue interface during transvenous cardiac ablation. Infrared endoscopy was performed during 24 catheter ablation attempts in 10 mongrel dogs. Infrared imaging was performed through a transparent dome located at the tip of a 7Fr steerable endoscope using an imaging wavelength of 1,620 nm. Radiofrequency ablation was performed using a 4-mm-tip electrode catheter. Attempts were made to identify the electrode-endocardial interface at each ablation site and to characterize any signal changes during ablation. The electrode-tissue interface could be identified at 19 of the 24 ablation sites. Changes at the electrode-tissue interface were observed during ablation at 14 sites, which included a gradual increase in the tissue signal intensity at 12 sites. Small lucencies near the ablation electrode were observed at six sites. There was no interference during energy delivery. Endocardial features identified by endoscopy correlated with the postmortem appearance. Direct imaging of intracardiac structures and the electrode-tissue interface can be achieved through blood during transvenous catheter ablation with infrared endoscopy using a steerable, fiberoptic, infrared endoscopic catheter. Ablation lesion formation can be seen as a gradual increase in signal intensity. Fiberoptic infrared endoscopy appears to be a promising new tool for guiding catheter ablation.

Transvenous catheter ablation of the right atrial free wall produces lung lesions in animals

Background: Most risks associated with transvenous catheter ablation are well known. One such risk, ablation beyond the targeted tissue, is sometimes encountered when the normal conduction system is ablated unintentionally or when pericarditis is observed. We hypothesized that, when ablating the right-atrial free wall (RAFWA), energy delivery might extend beyond the heart and ablate lung tissue.

CRAVT: A Prospective, Randomized Study Comparing Transvenous Cryothermal and Radiofrequency Ablation in Atrioventricular Nodal Re-entrant Tachycardia

Background Transvenous catheter ablation of atrioventricular nodal re-entrant tachycardia (AVNRT) with radiofrequency (RF) is effective and safe, but carries a 1–3% incidence of early and potentially late heart block. Cryothermy can create transient effects, and identify potentially successful ablation sites and decrease the risk for permanent heart block. Methods In this prospective, randomized trial 102 patients with recurrent narrow QRS-complex tachycardia suggestive of AVNRT were randomized to either RF or cryoablation before a diagnostic study. Results In 63 patients with AVNRT, 33 were randomized to RF and 30 to cryoablation. Procedural success was achieved, respectively, in 30 (91%) patients in the RF and 28 (93%) in the cryoablation group. The median number of cryothermal applications was significantly lower than the number of RF applications (2 versus 7, p <0.005). No accelerated junctional rhythm was seen with cryothermy, while it was present in 31/33 RF patients. Both fluoroscopy and procedural times were comparable. The radiological position of the successful site in relation to anatomical landmarks was slightly different ( p <0.05). No cryothermy related complications were observed, and no permanent AV conduction disturbances occurred. During a mean follow up of 13±7 months long-term clinical success was seen in one additional patient in each group. In the same period, 3 patients in both groups experienced recurrent AVNRT. Conclusion Cryoablation is as effective and safe as RF for AVNRT. Significantly fewer applications are necessary, with comparable procedure times. This makes cryothermy useful for the treatment of tachyarrhythmias near the compact AV node.