Radiofrequency Ablation of Atrial Fibrillation in Patients with Ebstein's Anomaly: A Two-Case Report.

Ebstein's anomaly (EA) is a rare congenital heart disease characterized by "atrialization" of the right ventricle, due to apical displacement of the tricuspid leaflets into the right ventricle. Patients with EA may develop all kinds of supraventricular arrhythmias requiring radiofrequency ablation. Atrial fibrillation (Afib) is a common arrhythmia in EA patients, and results in debilitating symptoms that often require surgical treatment. This is a follow-up report of 2 patients with EA undergoing radiofrequency ablation for Afib. The first patient underwent pulmonary vein isolation (PVI) and the ablation of a concomitant atrioventricular nodal reentrant tachycardia. The second patient was also treated with a PVI and a redo PVI 8 months later. Both patients remain in sinus rhythm 8 months on. Radiofrequency ablation is the therapy of choice for patients with pharmacological refractory Afib, but it is not common in patients with EA.

First experiences for pulmonary vein isolation with the high-density mesh ablator (HDMA): a novel mesh electrode catheter for both mapping and radiofrequency delivery in a single unit.

BACKGROUND: Interventional therapy of atrial fibrillation (AF) is often associated with long examination and fluoroscopy times. The use of mapping catheters in addition to the ablation catheter requires multiple transseptal sheaths for left atrial access. OBJECTIVES: The purpose of this prospective study was to evaluate feasibility and safety of pulmonary vein (PV) isolation using the high-density mesh ablator (HDMA), a novel single, expandable electrode catheter for both mapping and radiofrequency (RF) delivery at the left atrium/PV junctions. METHODS: Twenty-six patients with highly symptomatic paroxysmal AF (14, 53.8%) and persistent AF (12, 46.2%) were studied. Segmental PV isolation via the HDMA was performed using a customized pulsed RF energy delivery program (target temperature 55-60 degrees C, power 70-100 W, 600-900 seconds RF application time/PV). RESULTS: All 104 PVs in 26 patients could be ablated by the HDMA. Segmental PV isolation was achieved with a mean of 3.25 +/- 1.4 RF applications for a mean of 603 +/- 185 seconds. Entrance conduction block was obtained in 94.2% of all PV. The mean total procedure and fluoroscopy time was 159.0 +/- 32 minutes and 33.5 +/- 8.6 minutes, respectively. None of the patients experienced severe acute complications. After 3 months no PV stenosis was observed, and 85.6% and 41.6% of the patients with PAF and persistent AF, respectively, did not report symptomatic AF. CONCLUSIONS: In this first study of PV isolation using the HDMA, our findings suggest that this method is safe and yields good primary success rates. The HDMA simplifies AF ablation, favorably impacting procedure and fluoroscopy times.

Impact of irrigated energy application on the right coronary artery hemodynamics: FFR measurement in patients who underwent ablation of common type atrial flutter.

OBJECTIVE: The purpose of this first in vivo study was to assess the incidence of thermal influence to the right coronary artery (RCA) during ablation of common type atrial flutter (Aflu) by measuring the fractional flow reserve (FFR) in the vessel before, under and after ablation. METHODS: In thirty three patients ablated we performed coronary angiography (CA) before and at the end of the procedure. The FFR wire was positioned in the distal, the isthmus underlying, part of the RCA. Before and after the procedure FFR measurement was done at baseline and during adenosine administration. During the whole ablation procedure FFR measurement was continuously carried on, to monitor a transient thermal impact to the RCA. RESULTS: Of the 33 patients observed, 25 males, 8 females, mean age 58 +/- 9.5 years, none with CAD, all patients, except one with unidirectional block, were successfully ablated. The FFR at rest and under medication with adenosine before and after ablation was 0.985/0.949 and 0.981/0.942, respectively (p = ns). The CA of the RCA did not reveal any morphological change. The mean FFR while ablation declined from 0.94 to 0.904 (p = ns). Twenty-six patients (78.8%) had no or moderate decrease in FFR, seven patients (21.2%) demonstrated a substantial decrease [five patients (15.2%), FFR < 0.9 and >0.75] or significant change [two patients (6.1%)], FFR < 0.75 consistent with a remarkable or significant reduction of coronary flow. CONCLUSION: Ablation of AFlu did not alter RCA morphology; simultaneous FFR measurement showed severe depression of the FFR in a few patients, consistent with impairment in myocardial perfusion.

Quality of life and occurrence of atrial fibrillation in long-term follow-up of common type atrial flutter ablation: ablation with irrigated 5 mm tip and conventional 8 mm tip electrodes.

OBJECTIVES: The ablation of common type atrial flutter is mainly performed by two approved techniques, whose efficacy and outcome in terms of quality of life have not been evaluated so far in a long-term follow-up study over years. A high proportion of patients suffer from coexistent atrial fibrillation, which may worsen the ablation result. The question arises whether one technique is more effective than the other when immediate ablation results, the occurrence of atrial fibrillation and the quality of life are compared. Considering these facts, it is reasonable to think about new ablation strategies for common type atrial flutter in the era of new concepts in catheter ablation of atrial fibrillation. METHODS: In a retrospective study we evaluated a detailed questionnaire in 132 patients who underwent ablation of common type between 1999 and 2004. Radiofrequency ablation was performed irrespective of coexistent atrial fibrillation either with an irrigated tip or the 8 mm tip electrode. Acute and long-term ablation outcome, and the associated quality of life, pre-, under- and post-ablation was compared in the two different ablation groups. Recurrent tachycardia were re-evaluated by 12 lead ECG analysis and assessed for both ablation groups. RESULTS: 88 (67%) of the 132 patients contacted answered the questionnaire polling the perceived benefits of the procedure. Of the other 44 patients (33%); 4 (3%) had died, 7 (5.3%) had moved, 33 patients (25%) could not be included due to missing or incoherent answers. Independent of the ablation technique there was a high acute and long-term ablation success rate at about 95%. After a mean of 3 years of follow-up this benefit persists in spite of a high proportion of recurrent tachycardia, mainly atrial fibrillation (55/88 patients, 59.1%). Despite the occurrence of secondary tachycardia, there was a high significant long-term symptomatic benefit in the state of healthy and daily practice work, evaluated with a p-value of < 0.0005. The frequency of episodes and the symptom "tachycardia" were significantly reduced after effective ablation of common type atrial flutter, p-values of 0.003 and 0.002, respectively. Therefore the need for hospitalization was significant reduced (p = 0.001). Comparison of both approaches revealed that there was no significant difference related to the incidence and occurrence of atrial fibrillation. CONCLUSIONS: The two mainly accepted and applied techniques for the ablation of common type atrial flutter show an excellent outcome under the aspect of ablation efficacy and quality of life in longterm follow-up. Three years after the ablation procedure the majority of patients consider the intervention beneficial. Despite the relatively high appearance of atrial fibrillation in the long-term follow-up this effect is still traceable.

[Inhibition of the muscarinic potassium current by KB130015, a new antiarrhythmic agent to treat atrial fibrillation]. / Inhibition des muskarinergen Kaliumionenstroms durch das neue Klasse-III-Antiarrhythmikum KB130015 im Vergleich zu Ibutilide.

BACKGROUND AND PURPOSE: Vagus-induced atrial fibrillation is of particular clinical interest. The muscarinic potassium current I(K(ACh)) mediates the induction of vagus-induced atrial fibrillation. Selective inhibition of I(K(ACh)) seems to be an option to treat atrial fibrillation. The application of amiodarone, presently one of the most important antiarrhythmic agents in the parmacological treatment of atrial fibrillation, is limited by its adverse effects. KB130015, a new amiodarone derivative, and ibutilide are new class III antiarrhythmic agents. METHODS: In guinea-pig atrial myocytes the muscarinic potassium current (I(K(ACh))) was activated by acetylcholine and adenosine. The effect of KB130015 on I(K(ACh)) was measured using the whole-cell voltage-clamp method. RESULTS: KB130015 and ibutilide in a concentration of 50 microM effectively inhibited the muscarinic potassium current. The effect was concentrationdependent and reversible. The half-maximum effective concentration was 0.8 microM (KB130015) and 2.8 microM (ibutilide). The inhibition of I(K(ACh)) was independent of the mode of its activation. The adenosine-induced ion current was as well inhibited by both drugs as the acetylcholine-induced ion current. Via GTP-gamma-S irreversibly activated I(K(ACh)) was also inhibited by KB130015 and ibutilide, whereas intracellular application showed no effect on I(K(ACh)). CONCLUSION: KB130015 and ibutilide are potent inhibitors of IK(ACh). Their effect is most likely mediated by direct interaction with the extracellular part of the ion channel. Acute effects of KB130015 on ventricular myocardium are not known so far. Ibutilide on the other hand is known to inhibit I(kr). KB130015 is a promising antiarrhythmic agent for the pharmacotherapy of vagus-induced atrial fibrillation.

[Perspectives and limitations in the treatment of vagus-induced atrial fibrillation. Insights from cellular pharmacology]. / Effektivität und Proarrhythmie bei der pharmakologischen Behandlung des vagal induzierten Vorhofflimmerns. Erkenntnisse aus der zellulären Pharmakodynamik.

BACKGROUND AND PURPOSE: Pharmacological treatment of atrial fibrillation (AF) is limited by induction of malignant ventricular arrhythmias. Developing new drugs, a promising strategy is a more specific treatment of the atria. Muscarinic potassium current (IK[ACh]) is predominantly expressed in supraventricular tissue and mediates the induction of vagus-induced AF. The authors investigated the profile of representative class III drugs in respect to their effect on IK(ACh). METHODS: In rat atrial myocytes, IK(ACh) was activated by acetylcholine (ACh) measured with the whole-cell voltage clamp method. Drugs used: selective IKs blocker chromanole 293B (Cro); IKr blockers sotalol (Sot), dofetilide (Dof), ibutilide (Ibu), and terikalant (Ter). Data are expressed as mean values +/- standard deviation (SD). RESULTS: ACh-induced IK(ACh) density was 73 +/- 9 pA/pF (n= 9). IK(ACh) was almost completely desensitized in the presence of 50 micro M Ter, Ibu, or Dof. IC(50) of IK(ACh) inhibition by the three drugs was 0.9, 2.8, and 4.2 micro M (Dof, Ibu, and Ter, respectively). Receptor-independent GTP-gamma-S-induced IK(ACh) was sensitive to Ter, Ibu, and Dof as well. Sot is known to be a weak inhibitor of IKr. Inhibition of IK(ACh) by Sot was much less potent (IC(50) = 35.5 micro M) than inhibition by the high-affinity IKr blockers Ter, Ibu, and Dof. Superfusion of the cells with the IKs blocker Cro showed no desensitization of IK(ACh). Applied via the patch pipette (< 40 min) none of the class III drugs were effective. CONCLUSION: The results indicate inhibition of IK(ACh) and IKr but not IKs to be of similar mechanism (direct ion channel inhibition from the external side of the membrane). Potent desensitization of muscarinic potassium current could be of clinical relevance especially in patients with vagus-induced AF.