Total Radiofrequency Energy Research Articles

Efficacy and safety of a novel temperature-controlled catheter for cavotricuspid isthmus ablation.

Maintaining an adequate temperature at the target site is essential for effective ablation. We hypothesized that a tissue temperature-controlled (T-Con) catheter for cavotricuspid isthmus (CTI) ablation could improve the procedural ablation parameters. To evaluate the efficacy and safety of the T-Con (DiamondTemp™) catheter for CTI ablation compared with non-irrigation (Non-Irri) and irrigation (Irri) catheters. We analyzed 150 patients who underwent prophylactic CTI ablation combined with pulmonary vein isolation. The Non-Irri, Irri, and T-Con catheter groups comprised 50 patients each, and the ablation procedural parameters and complications were compared between these groups. There were no significant differences in clinical background characteristics among the three groups. The Kruskal-Wallis and post hoc tests demonstrated that the T-Con group showed the lowest total radiofrequency energy delivery time among the three groups (median [25 and 75 percentiles]: 340 [209, 357], 147 [100, 199], and 83 [61, 109] s, respectively in the Non-Irri, Irri, and T-Con groups; T-Con versus Non-Irri, p < .01; T-Con versus Irri, p < .01). The total procedural time and acute reconnection rate in the T-Con group (264 s and 4%, respectively) were lower than those in the Non-Irri group (438 s and 24%) but were similar to those in the Irri group (268 s and 6%). No significant complications were observed in any group. The T-Con catheter achieved a short energy delivery time and a low acute reconnection rate, indicating its potential as an alternative catheter for CTI ablation.

Effectiveness and Safety of High-Power Radiofrequency Ablation Guided by Ablation Index for the Treatment of Atrial Fibrillation.

Background To investigate the efficacy and safety of ablation index- (AI-) guided high-power radiofrequency ablation in the treatment of atrial fibrillation (AF). Methods Outcomes of radiofrequency (RF) applications were compared in a swine ventricular endocardial model (n = 10 each for 50 W, 40 W, and 30 W; AI = 500). And a total of 100 consecutive patients with paroxysmal AF undergoing pulmonary vein isolation (PVI) were included. The patients were divided into two groups (n = 50 for each) as follows: control group, treated with conventional power (30 W) ablation mode; and study group, treated with high power (40 W) radiofrequency ablation mode. All groups were treated with the same AI value guided the ablation (target AI = 400/500 on posterior/anterior wall, respectively). Acute pulmonary vein (PV) reconnection was assessed post adenosine administration 20 minutes after ablation. Subsequently, pathological observation of porcine heart lesions and necrotic tissue was performed. Additionally, statistical analyses were carried out on patients' baseline clinical characteristics, surgical data, and total RF energy. Results In swine ventricular endocardial RF applications, compared with 40 W and 30 W, the use of 50 W was associated with shallower tissue lesion depth (p < 0.001) and greater lesion maximum diameter (p < 0.001). Compared with 40 W and 30 W, tissue necrosis caused by 50 W was the deepest and largest (p < 0.001). In pulmonary vein isolation (PVI), there was no significant difference in baseline data between the study group and control group (p > 0.05). In patients with paroxysmal atrial fibrillation, the procedure time in the high-power group was significantly shortened (p < 0.001). The ablation time was significantly shorter (p < 0.001). Compared with control group, RF energy per point and acute pulmonary vein (PV) reconnection were lower (p < 0.001), and first-pass PVI was higher (p < 0.01) in study group. There were no significant differences in complications and sinus rhythm maintenance at 12 months between the two groups (p > 0.05). Conclusions Compared with conventional (30 W) PVI, AI-guided high-power (40 W) was safe and associated with shorter procedure time and reduced acute PV reconnection.

Relationship between luminal esophageal temperature and volume of esophageal injury during RF ablation: In silico study comparing low power-moderate duration vs. high power-short duration.

To model the evolution of peak temperature and volume of damaged esophagus during and after radiofrequency (RF) ablation using low power-moderate duration (LPMD) versus high power-short duration (HPSD) or very high power-very short duration (VHPVSD) settings. An in silico simulation model of RF ablation accounting for left atrial wall thickness, nearby organs and tissues, as well as catheter contact force. The model used the Arrhenius equation to derive a thermal damage model and estimate the volume of esophageal damage over time during and after RF application under conditions of LPMD (30 W, 20 s), HPSD (50 W, 6 s), and VHPVSD (90 W, 4 s). There was a close correlation between maximum peak temperature after RF application and volume of esophageal damage, with highest correlation (R2 = 0.97) and highest volume of esophageal injury in the LPMD group. A greater increase in peak temperature and greater relative increase in esophageal injury volume in the HPSD (240%) and VHPSD (270%) simulations occurred after RF termination. Increased endocardial to esophageal thickness was associated with a longer time to maximum peak temperature (R2 > 0.92), especially in the HPSD/VHPVSD simulations, and no esophageal injury was seen when the distances were >4.5 mm for LPMD or >3.5 mm for HPSD. LPMD is associated with a larger total volume of esophageal damage due to the greater total RF energy delivery. HPSD and VHPVSD shows significant thermal latency (resulting from conductive tissue heating after RF termination), suggesting a requirement for fewer esophageal temperature cutoffs during ablation.

The low acute effectiveness of a high-power short duration radiofrequency current application technique in pulmonary vein isolation for atrial fibrillation.

Application of high power radiofrequency (RF) energy for a short duration (HPSD) to isolate pulmonary vein (PV) is an emerging technique. But power and duration settings are very different across different centers. Moreover, despite encouraging preclinical and clinical data, studies measuring acute effectiveness of various HPSD settings are limited. Twenty-five consecutive patients with symptomatic atrial fibrillation (AF) were treated with pulmonary vein isolation (PVI) using HPSD. PVI was performed with a contact force catheter (Thermocool SF Smart-Touch) and Carto 3 System. The following parameters were used: energy output 50 W, target temperature 43°C, irrigation 15 mL/min, targeted contact force of > 10 g. RF energy was applied for 6-10 s. Required minimal interlesion distance was 4 mm. Twenty minutes after each successful PVI adenosine provocation test (APT) was performed by administrating 18 mg adenosine to unmask dormant PV conduction. All PVs (100 PVs) were successfully isolated. RF lesions needed per patient were 131 ± 41, the average duration for each RF application was 8.1 ± 1.7 s. Procedure time was 138 ± 21 min and average of total RF energy duration was 16.3 ± 5.2 min and average amount of RF energy was 48209 ± 12808 W. APT application time after PVI was 31.1 ± 8.3 min for the left sided PVs and 22.2 ± 4.6 min (p = 0.005) for the right sided PVs. APT was transiently positive in 18 PVs (18%) in 8 (32%) patients. Pulmonary vein isolation with high power for 6-10 s is feasible and shortens the procedure and ablation duration. However, acute effectiveness of the HPSD seems to be lower than expected. Further studies combining other ablation parameters are needed to improve this promising technique.

Ultrahigh density atrio-ventricular dual-chamber mapping as a next generation tool for ablation of accessory pathways.

Detailed three-dimensional (3D) mapping has been useful for effective radiofrequency catheter ablation. The Rhythmia system can create atrio-ventricular dual-chamber mapping, which reveals the atrial and ventricular potentials all at once in the same map. The aim of this study was to investigate the utility of mapping the atrium and ventricle simultaneously with a high-density 3D mapping system for the ablation of accessory pathways (AP). From July 2015 to August 2020, 111 patients underwent ablation of APs. Dual-chamber maps were created in 50 patients (median age 15 [10-54], 32 male [64.0%]), while 61 patients underwent radiofrequency (RF) ablation with conventional single-chamber 3D maps. The background characteristics and procedural details were compared between the dual-chamber mapping group and the conventional single-chamber mapping group. The number of RF applications (median [IQR]; 1.0 [1.0-3.0] vs. 3.0 [1.0-6.0], p = .0023), RF time (median [IQR], s; 9.2 [2.0-95.7] vs. 95.6 [4.1-248.7], p = .0107), and RF energy (median [IQR], J; 248.4 [58.7-3328.2] vs. 2867.6 [134.2-7728.4], p = .0115) were significantly lower in the dual-chamber group. The fluoroscopy time (median [IQR], min; 19.9 [14.2-26.1] vs. 26.5 [17.7-43.4], p = .0025) and fluoroscopy dose (median [IQR], mGy; 52.5 [31.3-146.0] vs. 119.0 [43.7-213.5], p = .0249) were also significantly lower in the dual-chamber than single-chamber mapping group. The dual-chamber mapping was useful for ablating accessory pathways and reducing the number of RF applications, total RF energy, and radiation exposure as compared with traditional mapping techniques.

HPSD ablation for AF high‐power short‐duration RF ablation for atrial fibrillation: A review

This manuscript reviews the literature for all in silico, ex vivo, in vitro, in vivo and clinical studies of high-power short-duration (HPSD) radiofrequency (RF) ablations. It reviews the biophysics of RF energy delivery applicable to HPSD and the use of surrogate endpoints to guide the duration of HPSD ablations. In silico modeling shows that a variety of settings in power, contact force and RF duration can result in the same surrogate endpoint value of ablation index and several HPSD combinations produce lesion volumes similar to a low-power long-duration (LPLD) RF application. HPSD lesions are broader with more endocardial effect and are slightly shallower but still transmural. The first 10 s of RF application is most important for lesion formation with diminishing effect beyond 20 s. The ideal contact force is 10-20 g with only a small effect beyond 30 g. In vitro and in vivo models confirm that HPSD makes transmural lesions that are often broader and shallower, and with proper settings, result in fewer steam pops than LPLD. One randomized trial shows better outcomes with HPSD and validates lesion size index as a surrogate endpoint. Clinical studies of HPSD using comparator groups of LPLD ablations uniformly show shorter procedure times and shorter total RF energy delivery for HPSD. HPSD generally has a higher first pass vein isolation rate and a lower acute vein reconnection rate than LPLD. Although not dramatically different from LPLD, long-term freedom from atrial fibrillation and complication rates seem slightly better with HPSD.

Abstract 13822: Comparison of Produced Potential Delay in Superior Vena Cava During Right Pulmonary Vein Isolation Between High-power Short-duration and Conventional Settings

Background: Recently, a high-power short-duration (HP-SD) setting has been introduced in atrial fibrillation (AF) ablation. Ablation using this setting reduces collateral tissue damage by shortening the conductive heating phase compared to conventional setting. However, the lesion characteristics have not been rigorously evaluated during ablation procedure. We hypothesized that superior vena cava (SVC) potential could be affected by excessive transmural lesions in anterior-superior right pulmonary vein isolation (PVI), adjacent to posterior aspect of SVC. Therefore, we compared the produced potential delay in SVC between HP-SD and conventional settings. Methods and Results: The consecutive 42 patients (61±10 years, 32 men) who underwent PVI for drug refractory AF were analyzed. Before introduction of HP-SD setting to AF ablation in November 2018, 14 patients underwent right PVI with conventional setting with output of 20-30 W (Conventional group). In the remaining 28 patients after then, right PVI was performed using HP-SD setting with output of 45-50 W (HP-SD group). We compared total radiofrequency energy and mean contact force along the anterior superior right PVI line between the 2 groups. Moreover, the produced SVC potential delay was calculated after anterior superior right PVI and compared between the 2 groups. Total radiofrequency energy delivered (6138 J vs. 6139 J, P = 0.999) and the mean contact force (17.2 g vs. 20.2 g, P = 0.100) in the anterior superior right PV did not differ between the HP-SD and Conventional groups. However, the produced SVC potential conduction delay after anterior superior right PVI was significantly longer in Conventional group compared to HP-SD group (6.2 ms vs. 0.5 ms, P &lt; 0.001). Conclusions: Our data suggest that HP-SD setting caused less collateral tissue damage than conventional setting during PVI. The significant produced SVC potential delay might be a surrogate marker of collateral tissue damage by conductive heating phase in PVI.

Ultra-Small Cell Networks With Collaborative RF and Lightwave Power Transfer

This paper investigates a hybrid radio frequency (RF)/visible light communication (VLC) ultra-small cell network consisting of multiple optical angle-diversity transmitters, one multi-antenna RF access point (AP) and multiple terminal devices. In the network, the optical transmitters play the primary role and are responsible for delivering information and power over the visible light while the RF AP acts as a complementary power transfer system. Thus, we propose a novel collaborative RF and lightwave resource allocation scheme for hybrid RF/VLC ultra-small cell networks. The proposed scheme aims to maximize the communication quality-of-service provided by the VLC under a constraint of total RF and light energy harvesting performance while keeping illumination constant and ensuring health safety. This scheme leads to the formulation of two optimization problems that correspond to the resource allocation at the optical transmitters and the RF AP. Both problems are optimally solved by appropriate algorithms. Moreover, we propose a closed-form suboptimal solution with high accuracy to tackle the optical transmitters’ resource allocation problem, as well as an efficient semi-decentralized method. Finally, simulation results illustrate the achievable performance of the investigated system and the effectiveness of the proposed solutions.

High-sensitivity cardiac Troponin T delta concentration after repeat pulmonary vein isolation

IntroductionDifference between high-sensitivity cardiac troponin T concentrations (hs-cTnT) before and after ablation procedure (delta concentration) reflects the amount of myocardial injury. The aim of the study was to investigate hs-cTnT prognostic power for predicting atrial fibrillation (AF) recurrence after repeat pulmonary vein isolation (PVI) procedure.Materials and methodsConsecutive patients with paroxysmal AF undergoing repeat PVI using a focal radiofrequency catheter were included in the study. Hs-cTnT was measured before and 18-24 hours after the procedure. Standardized 3, 6 and 12-month follow-up was performed. Cox-regression analysis was used to identify predictors of AF recurrence.ResultsA total of 105 patients undergoing repeat PVI were analysed (24% female, median age 61 years). Median (interquartile range) hs-cTnT delta after repeat PVI was 283 (127 - 489) ng/L. After a median follow-up of 12 months, AF recurred in 24 (23%) patients. A weak linear relationship between the total radiofrequency energy delivery time and delta hs-cTnT was observed (Pearson R2 = 0.31, P = 0.030). Delta Hs-cTnT was not identified as a significant long-term predictor of AF recurrence after repeated PVI (P = 0.920).ConclusionThis was the first study evaluating the prognostic power of delta hs-cTnT in predicting AF recurrence after repeat PVI. Delta hs-cTnT does not predict AF recurrence after repeat PVI procedures. Systematic measurement of hs-cTnT after repeat PVI does not add information relevant to outcome.

Atrial fibrillation ablation using very short duration 50\xa0W ablations and contact force sensing catheters

PurposeThe optimal radiofrequency (RF) power and lesion duration using contact force (CF) sensing catheters for atrial fibrillation (AF) ablation are unknown. We evaluate 50 W RF power for very short durations using CF sensing catheters during AF ablation.MethodsWe evaluated 51 patients with paroxysmal (n = 20) or persistent (n = 31) AF undergoing initial RF ablation.ResultsA total of 3961 50 W RF lesions were given (average 77.6 ± 19.1/patient) for an average duration of only 11.2 ± 3.7 s. As CF increased from < 10 to > 40 g, the RF application duration decreased from 13.7 ± 4.4 to 8.6 ± 2.5 s (p < 0.0005). Impedance drops occurred in all ablations, and for patients in sinus rhythm, there was loss of pacing capture during RF delivery suggesting lesion creation. Only 3% of the ablation lesions were at < 5 g and 1% at > 40 g of force. As CF increased, the force time integral (FTI) increased from 47 ± 24 to 376 ± 102 gs (p < 0.0005) and the lesion index (LSI) increased from 4.10 ± 0.51 to 7.63 ± 0.50 (p < 0.0005). Both procedure time (101 ± 19.7 min) and total RF energy time (895 ± 258 s) were very short. For paroxysmal AF, the single procedure freedom from AF was 86% at 1 and 2 years. For persistent AF, it was 83% at 1 year and 72% at 2 years. There were no complications.ConclusionsShort duration 50 W ablations using CF sensing catheters are safe and result in excellent long-term freedom from AF for both paroxysmal and persistent AF with short procedure times and small amounts of total RF energy delivery.

Multielectrode Pulmonary Vein Isolation Versus Single Tip Wide Area Catheter Ablation for Paroxysmal Atrial Fibrillation: A Multinational Multicenter Randomized Clinical Trial.

Single-shot ablation techniques may facilitate safe and simple pulmonary vein isolation to treat paroxysmal atrial fibrillation. Multielectrode pulmonary vein isolation versus single tip wide area catheter ablation-paroxysmal atrial fibrillation is the first multinational, multicenter, prospective, noninferiority randomized clinical trial comparing multielectrode-phased radiofrequency ablation (MEA) to standard focal irrigated radiofrequency ablation (STA) using 3-dimensional navigation. Patients with paroxysmal atrial fibrillation were randomized to MEA (61 patients) or STA (59 patients). Preprocedure transesophageal echocardiogram and computed tomography/magnetic resonance imaging (also 6-month postprocedure) were performed. Mean age was 57 years, 25% female sex, BMI was 28, CHA2DS2-VASc score was 0 to 1 in 82%, 8% had previous right atrial ablation, whereas all had at least 1 antiarrhythmic drug failure. The MEA group had significantly shorter mean procedure time (96±36 versus 166±46 minutes, P<0.001) and fluoroscopy time (23±9 versus 27±9 minutes, P=0.023). The total radiofrequency energy duration was 22±8 minutes for MEA versus 36±13 minutes for STA (P<0.001) with confirmed pulmonary vein isolation in all patients. Hospital admission was 1 day in both groups, without major adverse events either during the procedure or during 30-day follow-up. Two patients in the STA group had 1 PV with asymptomatic narrowing >50%. Freedom of atrial fibrillation for MEA and STA was 86.4% and 89.7% at 6 months, dropping to 76.3% and 81.0% at 12 months. In this multicenter, randomized clinical trial, MEA and STA had similar rates of single-procedure acute pulmonary vein isolation without serious adverse events in the first 30 days. MEA had slightly lower long-term arrhythmia freedom, but showed marked and significantly shorter procedure, fluoroscopy, and radiofrequency energy times. URL: www.clinicaltrials.gov; Unique identifier: NCT01696136.

The influence of cavotricuspid isthmus length on total radiofrequency energy to cure right atrial flutter

The complexity and success rate of right atrial flutter ablation is highly dependent on anatomical structures. The study comprised 35 consecutive patients (33-77 years old; 30 men) who underwent ablation of typical atrial flutter. The linear ablation line was measured offline as a surrogate for the cavotricuspid isthmus (CTI) length with the help of a three-dimensional mapping and navigation system (Ensite™). Biophysical parameters, such as total radiofrequency (RF) energy and time of the ablation procedure, were analysed to test the hypothesis that any of these variables show a correlation with the length of the ablation line. Bidirectional isthmus block was achieved in all cases. The isthmus length had a mean value of 32 ± 12 mm with a range of 14-57 mm. The linear regression between the CTI length and the total RF energy was not significant. There was no significant difference in energy (32.281 ± 25.587 vs. 37.136 ± 24.250 W-s, p = NS) or in the total ablation time (759 ± 646 vs. 802 ± 533 s, p = NS) between the group with short (< 29 mm; n = 17) vs. long CTI (≥ 29 mm, n = 18). When comparing different ablation technologies, total RF energy delivered with 8-mm catheter technology (group I) was significantly lower than in patients with cross over from 8-mm to cooled ablation technology (group III) (29.615 ± 12.331 vs. 62.674 ± 28.735 W-s, p = 0.01). The same was true for the comparison between cooled ablation technology (group II) and group III (19.879 ± 13.669 vs. 62.674 ± 28.735 W-s, p = 0.002). The length of the CTI as measured with help of a three-dimensional mapping system may reflect only a weak indicator for the complexity of flutter ablation procedures. The thickness of musculature and specific anatomy of the CTI seem to be the main challenges in performing a linear ablation to achieve bidirectional block.

Don't move during ablation of atrial fibrillation!

BackgroundRestless patient is recalcitrant during ablation of atrial fibrillation (AF). We aimed to assess the association between patient movements during AF ablation and its outcome. MethodsWe examined the body movement during AF ablation in 78 patients with the use of a novel portable respiratory monitor, the SD-101, which also has the ability to quantify the frequency of body movements. ResultsThe body movement index, defined as the number of the units of time with body movement events divided by the recording time (11.4±6.5events/h), was significantly correlated with the ablation time defined as the time from the first point of the ablation to the end of the procedure (1.2±0.3h) (r=0.35; p=0.0014) and a total radiofrequency energy applied (56.6±17.7kW) (r=0.36; p=0.0015). A multiple linear regression analysis showed that non-paroxysmal AF (β=0.25; p=0.036) and the body movement index (β=0.36; p=0.0019) were independent determinants of the ablation time. The body movement index was similar in patients with and without recurrence of AF. ConclusionsKeeping patients motionless may be important to reduce the procedural duration of AF ablation.

Bipolar versus multipolar radiofrequency (RF) ablation for the treatment of renal cell carcinoma: Differences in technical and clinical parameters

Purpose: This study aimed to compare retrospectively bipolar RF ablation with multipolar RF ablation for the treatment of renal cell carcinoma.Materials and methods: Between March 2009 and June 2012, 12 tumours (nine patients) treated with bipolar RF ablation (one applicator) and 14 tumours (11 patients) treated with multipolar RF ablation (two applicators) were compared systematically. Selection between bipolar RF ablation and multipolar RF ablation was operator choice considering tumour size. Study goals included differences in tumour and coagulation extent, and technical parameters (total RF energy delivery and RF ablation time per coagulation volume).Results: Tumour maximum diameter was significantly larger for multipolar RF ablation compared with bipolar RF ablation (27.0 mm versus 19.4 mm; p < 0.01). This difference is partially dependent on operator choice. Coagulation length, width and volume were significantly larger for multipolar RF ablation compared with bipolar RF ablation (35.0 mm versus 26.5 mm, 27.5 mm versus 23.0 mm and 14.3 cm3 versus 8.1 cm3; p < 0.01, p < 0.05 and p < 0.05, respectively). Coagulation circularity was not significantly different between both study groups (0.8 versus 0.8; not significant). Total RF energy delivery was significantly higher and RF ablation time per coagulation volume was significantly shorter for multipolar RF ablation compared with bipolar RF ablation (52.0 kJ versus 28.6 kJ and 2.4 min/cm3 versus 4.1 min/cm3; p < 0.05 and p < 0.05, respectively).Conclusions: Multipolar RF ablation creates a significantly larger coagulation width, but identical coagulation shape, compared with bipolar RF ablation. Additionally, multipolar RF ablation coagulates faster according to the shorter RF ablation time per coagulation volume.

Evaluation of the Efficacy of an Irrigated Catheter as Compared to Non-Irrigated for AF Ablation

Background: Irrigated catheters deliver more adequate radiofrequency energy for creating transmural lesions than conventional catheters for AF ablation. Objective: The aim of this study was to evaluate the efficacy of irrigated catheters as compared to non-irrigated for AF ablation. Methods: A total of 309 consecutive symptomatic AF patients underwent circumferential pulmonary vein isolation (CPVI). They were divided into three groups in a retrospective review; those that a 3.5-mm-irrigated (n=103, Group 1), 4-mm tip (n=100, Group 2) or 8-mm-tip catheter was used (n=106, Group 3). Results: The total radiofrequency energy was significantly greater in Groups 1 and 3 than in Group 2. A simultaneous ipsilateral both PVI occurred significantly more in Group 1 than in Groups 2 or 3. After a successful PVI, transient PV reconnections induced by an ATP injection in right PVs were significantly more decreased in Group 1 than in Group 3. The cumulative freedom from recurrence was significantly more decreased in Groups 1 and 3 than in Group 2 during a follow-up of 11.4±3.1 months (p<0.05). A multivariate logistic regression analysis indicated that using a 4-mm-tip catheter was the only independent predictor of AF recurrence (P=0.045). Conclusions: Irrigated catheters produced more simultaneous ipsilateral PVIs, less acute transient PV reconnections using ATP and less AF recurrence than non-irrigated. The outcomes in acute and chronic phases were better with irrigated catheters.

Comparison of Conventional 4 mm Tip Catheter and Open Irrigated Catheter in Circumferential Pulmonary Vein and Antrum Isolation for Paroxysmal Atrial Fibrillation

Background: Open irrigated catheter (OIC) has the advantage of radiofrequency (RF) ablation power delivery without thrombus formation. It had been proposed that OIC are capable of creating larger lesions resulting in greater efficacy. This study compared the efficacy and safety of OIC and conventional 4 mm tip catheter (NIC) retrospectively. Method: One hundred fifty-five patients underwent circumferential pulmonary vein and antrum isolation (CPVAI) using NIC (Group 1, 76 patients; temperature limited 55°C with maximum power 35 W) or OIC (Group 2, 79 patients; temperature cut 42°C and power set 30–40 W with a saline pump flow rate of 30 mL/min) were compared about ablation and procedural parameter and clinical outcome. Results: The procedural parameter (total procedure time, fluoroscopic time, total number of RF energy delivery) to achieve complete CPVAI was not significantly difference between two groups without total RF energy delivery (48635±10123 in Group 1 versus 77812±17505 J in Group 2; P<0.01). Three procedural complications were documented in Group 2 (cardiac tamponade, pericarditis, gastric hypomotility) and none in Group 1. During follow up period, AF free rate was not differed between two groups in short term follow up. Conclusion: CPVAI using OIC had more procedural complications than NIC ablation whether there is no apparent efficacy during ablation procedure and a similar outcome in this study. Farther examination would be necessary how to manage the power and irrigation flow setting while using OIC in CPVAI.

Comparison of the Point‐by‐Point versus Catheter Dragging Technique for Curative Radiofrequency Ablation of Atrial Fibrillation

The relationship between the applied techniques and clinical outcomes after radiofrequency (RF) ablation of atrial fibrillation (AF) remains unclear. We compared the results of ablation by RF delivered via a point-by-point versus catheter dragging technique for the treatment of AF. This study included 66 patients with drug-refractory AF who underwent circumferential pulmonary vein (PV) ablation. A point-by-point technique was used in 35 (53%) patients (Group I), and catheter dragging technique in the remaining 31 (47%) patients (Group II). If AF persisted or remained inducible after the PV isolation, additional ablation of complex fractionated atrial electrograms and linear ablation were performed. Significantly, fewer RF applications were delivered in Group II than in Group I. The total RF energy duration delivered was comparable between the two groups (P = 0.55). However, the total energy of RF deliveries was significantly greater in Group II than in Group I (P = 0.02). Despite a longer fluoroscopic exposure time (P = 0.01), the total procedural duration was significantly shorter in Group II than in Group I (P = 0.005). Within 3 months after a single ablation procedure, 24 patients (69%) in Group I versus 13 patients (42%) in Group II had ≥1 recurrence(s) of atrial tachyarrhythmias (P = 0.03). A multivariate analysis showed that a point-by-point ablation was the only independent predictor of early atrial tachyarrhythmia recurrences. The catheter dragging technique for ablation of AF was associated with a lower early recurrence rate of atrial tachyarrhythmias than the point-by-point technique.

Steerable Sheath Catheter Navigation for Ablation of Atrial Fibrillation: A Case‐Control Study

Lack of stable access to all desired ablation target sites is one of the limitations for efficacious circumferential left atrial (LA) pulmonary vein (PV) ablation. Targeting that, new catheter navigation technologies have been developed. The aim of this study was to describe atrial fibrillation (AF) mapping and ablation using manually controlled steerable sheath catheter navigation and to compare it against an ablation approach with a nonsteerable sheath. In this case-control-analysis 245 consecutive patients (controls) treated with circumferential left atrial PV ablation were matched with 105 subsequently consecutive patients (cases) ablated with a similar line concept but mapping and ablation performed with a manually controlled steerable sheath. One hundred sixty-six patients were selected to be included into 83 matched patient pairs. Ablation success was measured with serial 7-day Holter electrocardiograms. Patients ablated with the steerable sheath showed an increase in the success rate (freedom from AF) from 56% to 77% (P = 0.009) after a single procedure and 6 months of follow-up. With respect to procedural data no difference could be found for procedure time, fluoroscopy time, irradiation dose, and radiofrequency (RF) burning time. With the steerable sheath mean procedural RF power (33 +/- 9 vs 41 +/- 4 W; P < 0.0005) and total RF energy delivery (97,498 vs 111,864 J; P < 0.005) were significantly lower and the rate of complete PV isolation significantly increased from 10% to 52% (P < 0.0005). The complication rate was the same in both groups. Among different arrhythmia, procedure, and patient characteristics, the lack of early postinterventional arrhythmia recurrences was the only but powerful predictor for long-term ablation success. An AF mapping and ablation approach solely using a manually controlled steerable sheath for catheter navigation improved the outcome of circumferential left atrial PV ablation at similar intervention times and similar complication rates. The 6-month success rate after a single LA intervention increased from 56% to 77%.

Randomized Comparison of the Continuous vs Point-by-Point Radiofrequency Ablation of the Cavotricuspid Isthmus for Atrial Flutter

Achievement of complete conduction block in the cavotricuspid isthmus (CTI) is a curative ablation technique in patients with common atrial flutter (AFL). The present study was a prospective comparison of the efficacy of 2 ablation strategies in patients with common AFL: the continuous and point-by-point radiofrequency (RF) delivery techniques. Forty patients with common AFL were randomly assigned to either a group treated with a continuous RF delivery or to a group undergoing point-by-point RF ablation. In the first group, the RF energy was continuously delivered during a slow drag of the catheter tip from the tricuspid annulus to the inferior vena cava without stopping the application. In the second group, the RF ablation was performed using a point-by-point approach for 60 s at each point. All patients underwent ablation with an 8-mm-tip ablation catheter with a power limit of 50 W and a target temperature of 55 degrees C. Complete CTI conduction block was achieved in all patients. The patient characteristics, including the anatomy of the CTI estimated by 3-dimensional computed tomography, were no different between the 2 groups. The procedure time (time from the start of RF delivery to the completion of CTI block), fluoroscopic time and total RF energy required to create the CTI block between the continuous and point-by-point groups were 7.3+/-5.6 vs 21.2+/-22.2 min (p<0.01), 7.2+/-4.4 vs 16.2+/-14.1 min (p<0.05), and 15,631+/-6,001 vs 24,072+/-16,140 joules (p<0.05), respectively. There were no complications or recurrences of AFL during the follow-up period in any of the patients. In the curative treatment of common AFL, the continuous RF delivery approach could shorten the procedure and fluoroscopic time and reduce the total RF energy compared with the point-by-point RF ablation approach.

Effect of Radiofrequency Catheter Ablation on Plasma B‐type Natriuretic Peptide

The study was designed to investigate the impact of radiofrequency catheter ablation on the plasma level of B-type natriuretic peptide (BNP). In 36 patients who underwent catheter ablation of paroxysmal supraventricular tachycardia, the plasma level of BNP was analyzed before and after the ablation procedures. The plasma BNP at baseline, 30 minutes after the ablation, 3 and 24 hours after the ablation was 12.78 +/- 2.47, 18.45 +/- 4.02 (P = 0.446), 43.54 +/- 8.12 (P = 0.0001), and 17.88 +/- 4.71 (P = 0.493) pg/mL, respectively. Plasma troponin I was also increased 3 and 24 hours after the ablation (n = 10, P < 0.05). Multivariate regression analysis showed a significant correlation between the levels of BNP 3 hours after ablation and the preablation BNP and the total radiofrequency energy used for the ablation. We conclude that radiofrequency catheter ablation of supraventricular tachycardia increases the plasma level of BNP. The clinical significance of the ablation-induced increase in BNP needs to be further investigated.