Impact of tip design and thermocouple location on the efficacy and safety of radiofrequency application.

BACKGROUND: The FlexAbility™ SE catheter has a laser-cut 8Fr 4-mm flexible tip irrigated through laser-cut kerfs with a thermocouple 0.3 mm from the distal end. The TactiCath™ SE catheter has an 8Fr 3.5-mm tip and 6-irrigation port with a thermocouple 2.67 mm proximal to the tip. We investigated the impact of these differences on the efficacy and safety of radiofrequency (RF) applications. METHODS: RF applications at a range of powers (20 W, 30 W, and 40 W), contact forces (5 g, 15 g, and 25 g), and durations (10-60 s) using perpendicular/parallel catheter orientation were performed in excised porcine hearts. Lesion characteristics and incidence of steam pops were compared. RESULTS: A total of 540 lesions were examined. The FlexAbility™ SE catheter produced smaller lesion depths (4.0 mm vs. 4.4 mm, p = 0.014 at 20 W; 4.6 mm vs. 5.6 mm, p = 0.015 at 30 W), surface areas (22.7mm2 vs. 29.2mm2 at 20 W, p = 0.005; 23.2mm2 vs. 28.7mm2, p = 0.009 at 30 W), and volumes (126.1mm3 vs. 175.1mm3, p = 0.018 at 20 W; 183.2mm3 vs. 304.3mm3, p = 0.002 at 30 W) with perpendicular catheter placement. However, no differences were observed with parallel catheter placement. Steam-pops were significantly less frequently observed with the FlexAbility™ SE catheter (4% vs. 22%, p < 0.001) irrespective of catheter direction to the tissue. Multivariate analysis showed that use of the TactiCath™ SE catheter, power ≥ 40 W, contact force ≥ 25 g, RF duration > 30 s, parallel angle, and impedance drop ≥ 20Ω were significantly associated with occurrence of steam-pops. CONCLUSIONS: The FlexAbility™ SE catheter reduced the risk of steam-pops but produced smaller lesions with perpendicular catheter placement compared to the TactiCath™ SE catheter.

Retrograde fast pathway cryoablation inside the coronary sinus for slow-fast atrioventricular nodal reentrant tachycardia in a patient with persistent left superior vena cava.

INTRODUCTION: Persistent left superior vena cava (PLSVC) is accompanied by enlarged coronary sinus (CS) and deformation of the triangle of Koch. This makes anatomical evaluation of the atrioventricular (AV) nodal pathways difficult. METHODS: We attempted cryoablation of retrograde fast pathway located in the enlarged CS roof of PLSVC for slow-fast AV nodal reentrant tachycardia (AVNRT) induced by inadvertent antegrade fast pathway elimination during ablation of left atrial tachycardia. RESULTS: Slow-fast AVNRT was successfully eliminated without AV block progression. CONCLUSIONS: This is the first case of successful retrograde fast pathway ablation of the CS ostial roof for slow-fast AVNRT with PLSVC.

Species differences in liver microsomal hydrolysis of acyl glucuronide in humans and rats.

Acyl glucuronides (AGs) are known as one of the causes of idiosyncratic drug toxicity (IDT). Although AGs can be enzymatically hydrolysed by ß-glucuronidase and esterase, much information on their characteristics and species differences is lacking. This study was aimed to clarify species differences in AG hydrolysis between human and rat liver microsomes (HLM and RLM).To evaluate the AG hydrolysis profile, and the contribution of ß-glucuronidase and esterase towards AG hydrolysis in HLM and RLM, nonsteroidal anti-inflammatory drugs (NSAIDs) were used. AGs were incubated with 0.1 M Tris-HCl buffer (pH 7.4) and 0.3 mg/mL HLM or RLM in the absence or presence of ß-glucuronidase inhibitor, D-saccharic acid 1,4-lactone (D-SL) and esterase inhibitor, phenylmethylsulfonyl fluoride (PMSF).AGs of mefenamic acid (MEF-AG) and etodolac (ETO-AG) showed significantly higher AG hydrolysis rates in RLM than in HLM. Esterases were found to serve as AG hydrolases dominantly in HLM, whereas both esterases and ß-glucuronidase equally contribute to AG hydrolysis in RLM. However, MEF-AG and ETO-AG were hydrolysed only by ß-glucuronidase.We demonstrated for the first time that the activity of AG hydrolases towards NSAID-AGs differs between humans and rats.

Pulmonary Vein Perforation and Life-Threatening Hemoptysis During Cryoballoon Ablation for Persistent Atrial Fibrillation.

Cryoballoon ablation is an effective method for pulmonary vein isolation for atrial fibrillation; however, unexpected complications may occur while performing the ablation procedure. We report an extremely rare case of pulmonary vein perforation with hemoptysis that required emergency lobectomy caused by injury from a circular mapping catheter. (Level of Difficulty: Intermediate.).

Prevalence of gastric hypomotility after additional cryoballoon ablation of the left atrial roof.

INTRODUCTION: Gastric hypomotility (GH) is a major complication of atrial fibrillation (AF) ablation. We aimed to clarify whether additional cryoballoon ablation (CBA) of the left atrial (LA) roof is associated with GH. METHODS AND RESULTS: This study included 54 patients with non-paroxysmal AF who underwent CBA for pulmonary vein isolation and of the LA roof line. GH was defined according to the results of esophagogastroscopy performed 2 days after ablation. GH was observed in 10 patients. There were significant differences in LA diameter (LAD), right inferior pulmonary vein (RIPV) diameter, and the height of the LA roof from the point where the LA posterior wall and esophagus make contact between patients with (GH+) and without GH (GH-) (LAD: 41.0 [36.3-41.8] mm vs. 46.5 [42.8-50.0] mm, p < .01; RIPV diameter: 19.7 [19.0-20.5] mm vs. 23.2 [21.2-24.9] mm, p < .01; height of LA roof: 5.7 [5.1-6.1] mm vs. 8.8 [7.1-11.2] mm for, p < .01, respectively). Multivariate analysis revealed that LA roof height was a predictor of GH. Moreover, Patient Assessment of Upper Gastrointestinal Disorders-Symptom Severity Index (PAGI-SYM) scores increased significantly 1 week after ablation (from 1.0 [0.0-2.8] to 5.0 [3.0-11.0], p = .03) in patients with GH. CONCLUSION: The height of the LA roof may be a predictor of GH after CBA of the LA roof line. Additionally, GH-related symptoms may still appear 1 week after ablation.

Cryoballoon ablation of the left atrial posterior wall reduces recurrence of persistent atrial fibrillation in patients with non-paroxysmal atrial fibrillation.

BACKGROUND: This study aimed to clarify the clinical outcomes of cryoballoon ablation of the left atrial (LA) posterior wall (LAPW), including the LA roof, in patients with non-paroxysmal atrial fibrillation (AF). METHODS: We analyzed the outcomes of 284 patients with non-paroxysmal AF, of whom 210 underwent the cryoballoon ablation of the LAPW, including the LA roof, in addition to pulmonary vein isolation with a cryoballoon. RESULTS: Complete conduction block at the LA roof was obtained in 95.7% (201/210) of patients, and LAPW was isolated in 83.3% (130/156) of patients. Over 372 (range, 208-477) days of follow-up, atrial arrhythmia recurrence was observed in 84 (29.6%) patients, and atrial tachycardia (AT) recurrence accounted for 27.4% of cases. The prevalence of LA roof cryoballoon ablation was significantly higher in patients without recurrence than in those with recurrence (78.6% vs. 63.1%, respectively; p = .01), especially those with persistent AF recurrence (77.0% vs. 55.0%, p = .01). No significant difference was found in the prevalence of AT recurrence between patients who had undergone additional LAPW ablation and those who had not. Durable LA roof lesions were confirmed in 29 (72.5%) of 40 patients who underwent redo ablation. CONCLUSIONS: Cryoballoon ablation of the LAPW leads to a sufficient acute success rate of complete conduction block and durable lesions of the LA roof without increasing AT recurrence risk. The prevalence of persistent AF recurrence decreases after additional cryoballoon ablation of the LAPW in patients with non-paroxysmal AF.

Meta-analysis of controlled studies on minimally interrupted vs. continuous use of non-vitamin K antagonist oral anticoagulants in catheter ablation for atrial fibrillation.

AIMS: At present, there are no guideline recommendations for minimally interrupted use of non-vitamin K antagonist oral anticoagulants (mi-NOAC) during catheter ablation (CA) for atrial fibrillation (AF). Current evidence is predominantly based on observational studies, with continuous use of vitamin K antagonist in the control arm. This quantitative summary reflects the first high-level evidence on contemporary regimens, with continuous NOAC use (c-NOAC) as the current gold standard. METHODS AND RESULTS: Meta-analysis (Pubmed, Embase, and Web of Science) on prospective, controlled studies comparing contemporary mi-NOAC (without bridging) with c-NOAC. Net adverse clinical events (major bleeding, thrombo-embolic events) were the primary outcome. In addition, we analysed total bleeding, minor bleeding, and silent cerebral embolism. Eight studies (six randomized, two observational) with 2168 patients were summarized. The primary endpoint occurred in 1.0% (18/1835): 1.1% (11/1005) vs. 0.8% (7/830) for the mi-NOAC and c-NOAC groups, respectively; odds ratio (OR) 1.20 [95% confidence interval (CI) 0.49-2.92, P = 0.64]. The OR for total bleeding on mi-NOAC was 1.26 (95% CI 0.97-1.63, P = 0.07). ORs for minor bleeding and silent cerebral embolism were 1.17 (95% CI 0.80-1.70, P = 0.34) and 2.62 (95% CI 0.54-12.61, P = 0.12), respectively. CONCLUSION: This synopsis provides a quantitative synthesis of high-level evidence on a contemporary strategy of mi-NOAC in CA for AF, and overall clinical outcomes were not different from continuous NOAC use. Despite preprocedural interruption, there was no sign of lower bleeding rates. Additional higher volume datasets are warranted for more precise treatment effect estimations of this everyday alternative anticoagulation strategy in AF ablation.

Prone-position computed tomography in the late phase for detecting intracardiac thrombi in the left atrial appendage before catheter ablation for atrial fibrillation.

BACKGROUND: Contrast computed tomography (CT) is a useful tool for the detection of intracardiac thrombi. We aimed to assess the accuracy of the late-phase prone-position contrast CT (late-pCT) for thrombus detection in patients with persistent or long-standing persistent atrial fibrillation (AF). METHODS: Early and late-phase pCT were performed in 300 patients with persistent or long-standing AF. If late-pCT did not show an intracardiac contrast defect (CD), catheter ablation (CA) was performed. Immediately before CA, intracardiac echocardiography (ICE) from the left atrium was performed to confirm thrombus absence and the estimation of the blood velocity of the left atrial appendage (LAA). For patients with CDs on late-pCT, CA performance was delayed, and late-pCT was performed again after several months following oral anticoagulant alterations or dosage increases. RESULTS: Of the 40 patients who exhibited CDs in the early phase of pCT, six showed persistent CDs on late-pCT. In the remaining 294 patients without CDs on late-pCT, the absence of a thrombus was confirmed by ICE during CA. In all six patients with CD-positivity on late-pCT, the CDs vanished under the same CT conditions after subsequent anticoagulation therapy, and CA was successfully performed. Furthermore, the presence of residual contrast medium in the LAA on late-pCT suggested a decreased blood velocity in the LAA ( ≤ 15 cm/s) (sensitivity = 0.900 and specificity = 0.621). CONCLUSIONS: Late-pCT is a valuable tool for the assessment of intracardiac thrombi and LAA dysfunction in patients with persistent or long-standing persistent AF before CA.

Vagal Reactions During Laser Balloon Ablation in Patients with Paroxysmal Atrial Fibrillation.

Radiofrequency and cryoballoon applications around the pulmonary veins (PVs) could provoke a vagal reflex (VR) by modulating the intrinsic cardiac autonomic nervous system (ICANS).This study aimed to investigate the incidence, timing, and clinical impact of a VR provoked by a laser balloon application for a PV isolation (PVI).A total of 92 consecutive paroxysmal atrial fibrillation (PAF) patients underwent a laser balloon PVI of PAF. Acute changes in the heart rate and blood pressure were recorded. The heart rate variability (HRV) was tested by Holter ECGs before and at three months following the ablation. Three hundred forty-five out of 363 PVs were successfully isolated (97%) with laser balloon applications. A VR such as sinus bradycardia (26.1%), transient sinus arrest (9.8%), transient atrioventricular block (1.1%), or a blood pressure reduction (8.7%) was observed during the laser balloon applications for the PVI. The follow-up ended at 12 months. The HRV attenuation was comparable before and at three months after the ablation procedure between that with and without a VR (P = 0.14). The PAF recurrence rate was also comparable between the two groups (P = 0.882).The laser balloon PVI often provoked a VR, however, the modulation of the ICANS was temporary and for up to three months as measured by the HRV changes after the ablation, and the freedom from any atrial fibrillation recurrence was comparable regardless of the occurrence of a VR.

Predictors of the "Crosstalk" Phenomenon During Cryoballoon Ablation in Patients with Atrial Fibrillation.

Second-generation cryoballoon (CB) ablation is effective in achieving pulmonary vein (PV) isolation (PVI) in atrial fibrillation (AF) patients. The "crosstalk" (CST) phenomenon has been reported to reduce unnecessary applications during CB ablation. Nevertheless, it is unclear under what conditions the CST phenomenon occurs.To seek the predictors of the CST phenomenon during CB-guided PVI, CST phenomenon in achieving ipsilateral superior PVI during inferior PV ablation was analyzed in AF patients who underwent de novo ablation using CB. CB occlusion status and nadir balloon temperature (NT) were compared in these patients, and all ablated superior PVs were categorized into three groups according to the necessity of the touch up ablation and effectiveness of the phenomenon.Of 1082 superior PVs, 16, 40, and 1026 were classified into the CST success, CST failure, and control groups (unnecessary CST), respectively. The proportion of superior PVs ablated with complete occlusion using the CB was significantly higher in the CST success group than in the other two groups. The proportion of superior PVs ablated with NT ≤ -46°C was higher in the CST success group than in the CST failure group. The CST phenomenon was always observed if CB ablation of the superior PVs was performed with both complete occlusion and NT ≤ -46°C and was almost always ineffective if it did not meet these two criteria (sensitivity, 100%; specificity, 93%).Successful CST ablation was highly predicted if complete PV occlusion and NT ≤ -46°C during CB ablation of the superior PVs were achieved.

Predictors of Phrenic Nerve Injury During Pulmonary Vein Isolation for Curing Atrial Fibrillation With Balloon-Based Visually Guided Laser Ablation.

BACKGROUND: Pulmonary vein (PV) isolation (PVI) with balloon-based visually guided laser ablation (VGLA) is useful for treating atrial fibrillation (AF), but phrenic nerve injury (PNI) is an important complication. We investigated the predictors of developing PNI during VGLA.Methods and Results:We included 130 consecutive patients who underwent an initial VGLA of non-valvular paroxysmal AF. Twenty patients developed PNI during the PVI. The patients with PNI had a significantly larger right superior PV ostial area (RSPVOA) than the other patients (mean [±SD] 284.7±47.0 vs. 233.1±46.4 mm2, respectively; P<0.01). Receiver operating characteristic analyses revealed that the area under the RSPVOA curve was 0.79 (95% confidence interval [CI] 0.69-0.90) with an optimal cut-off point of 238.0 mm2(sensitivity, 0.58; specificity, 0.95). In multivariate analyses, a large RSPVOA (HR 1.02, 95% CI 1.01-1.03, P<0.01) and small balloon size (HR 0.70, 95% CI 0.50-0.99, P=0.04) were independent risk factors for PNI during VGLA. PNI remained in 13 patients after the procedure, but 12 of these patients recovered from the PNI during the follow-up period. CONCLUSIONS: The incidence of PNI during VGLA was relatively high, but PNI improved in most cases. A large RSPVOA and small balloon size were predictors of PNI during VGLA.

Blood Coagulation Status during Cryofreezing Ablation and Effects of the Direct Anticoagulants Dabigatran and Edoxaban.

Cryoballoon ablation is an established catheter-based approach to treat atrial fibrillation (AF). However, thromboembolic events cannot be avoided during cryoablation. There is little data regarding the blood coagulation status during freezing.The thrombin antithrombin complex (TAT) and prothrombin fragment 1+2 (F 1+2) of patient blood were measured during cryoballoon application when the cryoballoon temperature reached the nadir in 63 AF patients. TAT was also measured from porcine blood during cryoballoon freezing in 5 pigs.The TAT and F 1+2 increased from 6.60 ± 5.65 to 9.16 ± 7.28 ng/mL (P = 0.004) and from 279.6 ± 146.4 to 323.6 ± 169.1 pmol/L (P = 0.003) between the control and during freezing, respectively. The TAT increased from 0.46 to 0.87 ng/mL during freezing compared to that of pre-freezing (P < 0.05), and it returned to 0.39 ng/mL in 30 minutes after an intravenous edoxaban administration (N.S.).Dabigatran failed to exert sufficient anticoagulant effects during cryofreezing. In contrast, intravenous edoxaban seemed to provoke anticoagulation effects under extreme low temperature circumstances.

Clinical investigation of the durability of the lesions created by left atrial linear ablation with a cryoballoon.

INTRODUCTION: Pulmonary vein isolation (PVI) and linear ablation with a roof line and bottom line on the left atrial (LA) posterior wall (LAPW) can be achieved with a cryoballoon (CB). This study sought to investigate the long-term durability of these linear lesions. METHODS AND RESULTS: Among 290 persistent patients with atrial fibrillation (AF) who had undergone linear ablation with a CB on the roof and bottom line of the LAPW in addition to the PVI, we analyzed those patients who underwent a re-do AF ablation. Arrhythmia recurrence was confirmed in 70 (24%) out of 290 patients, and 47 (16%) patients underwent re-do sessions. At the beginning of the re-do ablation, we examined the reconnection sites of the linear lesions on the LAPW and PVI. Maintenance of the conduction block on the LAPW roof and bottom lines was observed in 35 out of 47 patients (74.5%), and 16 out of 35 patients (45.7%), respectively. The length of the roof line was significantly shorter in patients with preservation of the conduction block on the LAPW roof than in those without (36.2 ± 6.5 mm vs 41.6 ± 4.7 mm, P = .02). CONCLUSION: Durable lesions could be obtained after linear ablation with the CB for the LAPW roof line, especially in those with a relatively short LAPW roof line. However, patients requiring touch-up ablation with radiofrequency were included, and that was associated with a potential financial implication.

Experimental Study with Regard to the Effects of Energy Titration of the Laserballoon on the Lesion Creation Using Porcine Myocardium.

Laserballoon-based pulmonary vein isolation has proven to be safe and effective. However, the influence of the laser energy titration on the lesion formation has never been fully investigated. The aim of this study was to determine the relationship between the delivered laser energy and lesion size, as well as the incidence of steam pop.The whole porcine heart was excised, and the left ventricular myocardium was separated into four specimens. Myocardial specimens were embedded in a warm mattress to keep the myocardial temperature around 37°C. The laserballoon was located so that the surface of the laserballoon was attached to the myocardium. The laser energy was irradiated against the surface of myocardium at 5.5, 8.5, 10.0, and 12.0 W for 3, 5, 10, and 20 seconds. The depth, surface area, and lesion volume were measured using a digital vernier caliper.At constant laser energy and time, the lesion size increased significantly with the increasing energy (P < 0.001) and application duration (P < 0.001). The steam pop was provoked when a 12.0 W laser energy was applied for longer than 16 seconds, and it occurred in 2 out of 8 lesions.The laserballoon demonstrated the ability to create a lesion formation in a dose- and time-dependent manner. Steam pop could be provoked with high-energy irradiation.

Clinical impact of rapid ventricular pacing on the left atrial posterior wall isolation by a cryoballoon application: a randomized controlled trial.

PURPOSE: Rapid ventricular pacing (RVP) was reported to improve the cooling effects of the cryoballoon (CB). The aim of this study was to investigate the safety and efficacy of RVP for left atrial posterior wall isolation (PWI) by the CB. METHODS: One hundred consecutive patients (males 80, mean age 63 ± 10 years) with persistent atrial fibrillation underwent left atrial roof (LA-RB) and bottom block line (LA-BB) creation by CB to achieve PWI. Patients were randomized into two groups according to whether they underwent PWI with (RVP group, n = 50) or without RVP (control group, n = 50). RESULTS: The nadir CB temperature (NCT) during the LA-RB and LA-BB creation was significantly lower in the RVP group than control group (LA-RB - 45.7 °C and - 43.9 °C, p < 0.001, and LA-BB - 42.4 °C and - 40.0 °C, p < 0.001). The success rate of the LA-RB creation was significantly higher in the RVP group than the control group (98% vs. 88%, p = 0.039), however, there were no significant differences regarding the LA-BB creation (66% vs. 52%, p = 0.15) and PWI (66% vs. 50%, p = 0.1) between the two groups. The PWI success rate did not differ whether CB freezing was prematurely terminated due to an excessive luminal esophageal temperature (LET) drop in the RVP group (65.8% vs. 66.7%, respectively, p = 0.96). CONCLUSIONS: RVP significantly decreased the NCT during the CB application resulting in the significant improvement of success rate of the LA-RB. The advantage of RVP in terms of the accomplishing PWI was not affected even when the CB freezing was prematurely terminated due to an excessive LET drop.

Chemical mapping as a predictor of vein of Marshall ethanol ablative effects.

PURPOSE: The aim of this study was to test regional pharmacological effects of an antiarrhythmic agents to predict ablative effects. BACKGROUND: The vein of Marshall (VOM) providing vascular access to myocardial tissue has been used for ablative purposes using ethanol. METHODS: A total of 35 patients (male 21, 63.2 ± 7.8 years old) were included. A balloon-tipped infusion catheter was inserted into the VOM. Endocardial ultrahigh-resolution mapping was performed along the VOM region to record the change in atrial electrograms (AEs) after VOM injection of cibenzoline of 3.5 mg during sustained atrial fibrillation (AF). Subsequently, ethanol was infused into the VOM and ablative region was mapped. RESULTS: In 17 patients (49 %), cibenzoline reduced AEs amplitude by >50%, all of which had also complete elimination of AEs following ethanol (Group A). In 18 patients (Group B), cibenzoline failed to eliminate AEs; yet, in 13 of 18 AEs were eliminated by ethanol. In the remaining five patients, ethanol did not eliminate AE. CONCLUSIONS: Cibenzoline into the VOM could reliably predicts the results of subsequent ethanol infusion into the VOM using ultrahigh-resolution mapping system, which leads to avoid unnecessary permanent lesion creation by ethanol infusion.

Chemical ablation of ventricular tachycardia arising from the left ventricular summit.

Ventricular tachycardia (VT) arising from the left ventricular summit is very tough to treat endocardially and epicardially due to the distance from the VT origin and close proximity to the coronary arteries, respectively. Ethanol infusions into coronary veins feeding VT origins were able to safely abolish this type of VT.