How to avoid unnecessary RF applications in cavo-tricuspid isthmus: common atrial flutter ablation using 8-mm-tip mini-electrode-equipped catheter.

PURPOSE: Eight-millimeter-tip ablation catheters are characterized by poor mapping resolution as they depend on electrode size and spacing. IntellaTip MiFi XP 8-mm (Boston Scientific) catheters offer high mapping resolution due to 3 mini-electrodes (ME) located at the distal tip of the catheter and are dedicated for cavo-tricuspid isthmus (CTI) radiofrequency ablation (RFA). The aim of the study was to evaluate the usefulness, effectiveness and safety of novel IntellaTip MiFi XP catheter for CTI RFA and its ability to localize anatomical structures of the heart. METHODS: The study included 10 patients referred for atrial flutter ablation. The 3D mapping system EnSite Velocity was utilized for catheter visualization. The ME signals were used for tricuspid annulus visualization, RF delivery effectiveness assessment defined as ME signal attenuation, and localization of the gaps in the ablation line. The use of ME signals for TV annulus localization resulted in a 13.9 mm (35.5 ± 4.8 mm vs 49.4 ± 7.8 mm; p < 0.01) shorter ablation line in comparison with the potential ablation line designed using standard bipol. The ablation endpoint, bidirectional block, was achieved in all 10 cases (100%) and lasted for at least 15 min after the last RF delivery. The ablation endpoint was reached after 5.1 ± 1.67 RF applications. The total RF time was 220 ± 61 s. Total procedure time was 66 ± 13.5 min, fluoroscopy time 3.92 ± 4.21 min, and total fluoroscopy dose 40.3 ± 56.5 mGy. RESULTS: In 3 out of 10 cases, there was a need of filling the gap with 1-2 additional applications after the first linear lesion set. No additional RF applications were required at the annular end of the ablation line. The indirect comparison with previously conducted studies using a standard 8-mm ablation catheter shows that the studied catheter has at least the same or even better performance. CONCLUSIONS: The use of the novel IntellaTip MiFi XP may help to avoid unnecessary RF application especially at the annular part of cavo-tricuspid isthmus and enables a purely electrophysiological approach to atrial flutter ablation, as high-resolution ME signals help to understand local electrophysiological phenomena.

A Retrospective Study of Atrial Fibrillation Following Cavotricuspid Isthmus Ablation for Atrial Flutter.

BACKGROUND Catheter radiofrequency ablation for typical atrial flutter is considered to be safe and effective. However, atrial fibrillation (AF) following cavotricuspid isthmus ablation for atrial flutter has been reported in patients without a previous history of AF, which has implications for the decision to use oral anticoagulation. This retrospective study at a single center aimed to evaluate the occurrence of AF in patients after successful cavotricuspid isthmus ablation of typical atrial flutter and to determine the incidence and associations with AF during follow-up. MATERIAL AND METHODS Between January 2011 and July 2017, of 110 consecutive patients who underwent cavotricuspid isthmus ablation for typical atrial flutter, 67 patients had no previous history of AF, of which 40 patients underwent follow-up. The 40 patients included in this retrospective clinical study included 34 men and 6 women, with a mean age of 67±10 years. RESULTS Forty patients underwent post-ablation follow-up for 46±23 months, and 12 patients (30%) developed AF; six patients (15%) experienced recurrent of atrial flutter. More than half of the patients with post-ablation AF were asymptomatic with a European Heart Rhythm Association (EHRA) score of 1, and univariate analysis showed the absence of variables associated with the prevalence of AF. CONCLUSIONS Following cavotricuspid isthmus ablation for atrial flutter, recurrence of atrial flutter was found in 15% of cases, and asymptomatic AF occurred in 30%. These findings have implications for the use of post-ablation oral anticoagulation treatment, which is often discontinued following ablation therapy and before patient follow-up.

Effect of Antazoline on Electrophysiological Properties of Atrial Muscle and Conduction System of the Heart.

PURPOSE: Antazoline is a first-generation antihistaminic agent with additional anticholinergic properties and antiarrhythmic potential. Recent data shows its high effectiveness in sinus rhythm restoration among patients with paroxysmal atrial fibrillation. The effect of antazoline on electrophysiological parameters of the heart in vivo has not yet been examined. The aim of this study was to evaluate changes in electrophysiological parameters of the heart muscle and conduction system as a response to increasing doses of antazoline. METHODS: After successful ablation of supraventricular arrhythmias, the electrophysiological parameters: sinus rhythm cycle length (SRCL), AH, HV, QRS, QT, QTc intervals, Wenckebach point (WP), sinus node recovery period (SNRT), intra- (hRA-CSos) and interatrial conduction time (hRA-CSd), right and left atrium refractory period (RA-; LA-ERP), and atrioventricular node refractory period (AVN-ERP) were assessed initially and after 100, 200, and 300 mg of antazoline given intravenously. RESULTS: Fifteen patients (8 males, 19-72 years old) undergoing EPS and RF ablation were enrolled. After 100 mg bolus, a significant reduction in SRCL was noticed. After antazoline administration, significant prolongation of HV, QRS, QTc, hRA-CSos, hRA-CSd intervals, RA- and LA-ERP and reduction of SRCL were observed. After a total dose of 300 mg, QT interval prolonged significantly. Increasing the dose of antazoline had no impact on AH, Wenckebach point, AVN-ERP, and SNRT. CONCLUSION: Antazoline has an effect on electrophysiological parameters of the atrial muscle and has rapid onset of action. No negative effect on sinus node function and atrioventricular conduction in a unique property among antiarrhythmic drugs.