Treatment of atrial tachycardia arising after superior transseptal approach mitral valve surgery: Insights from ultra-high-density mapping to prevent atrioventricular block.

INTRODUCTION: Mitral valve surgery employing a superior transseptal approach (STA) is associated with arrhythmogenicity and intra-atrial conduction delay, despite being optimal for visualization of the surgical field. It is sometimes difficult to treat atrial tachycardias (AT) that arise after STA. To investigate AT circuits that arise after STA in detail in order to identify the optimal ablation line, using ultra-high-resolution mapping (UHRM). METHODS: We retrospectively analyzed 12 AT from 10 patients (median age 70 years, nine males) who had undergone STA surgery. The tachycardias were mapped using the Rhythmia mapping system (Boston Scientific, Natick, Massachusetts). RESULTS: The 12 STA-related AT (STA-AT) circuits were classifiable as follows according to location of the optimal ablation line: (1) peri-septal incision STA-AT (n = 3), (2) cavotricuspid isthmus (CTI) dependent STA-AT (n = 7), and (3) biatrial tachycardia (n = 2). Radiofrequency (RF) application terminated 11 of the 12 STA-AT. We found that difference in STA-AT circuit type was due to characteristics of the septal incision line made for STA. UHRM was important in identifying optimal ablation sites that did not create additional conduction disturbances in the right atrium (RA). CONCLUSIONS: ATs after STA involve complex arrhythmia circuits due to multiple and long incision lines in the RA. Accurate understanding of the arrhythmia circuit and sinus conduction in the RA after STA is recommended for treating post-surgical tachycardia in a minimally invasive manner.

Association between pericoronary adipose tissue attenuation and outcome after second-generation cryoballoon ablation for atrial fibrillation.

OBJECTIVES: Previous studies reported the association between inflammation and atrial fibrillation (AF). Pericoronary adipose tissue (PCAT) attenuation, PCATA, on cardiac CT angiography (CTA) reflects pericoronary inflammation. We hypothesized that the PCATA predicts AF recurrence after cryoballoon ablation (CBA) for paroxysmal and persistent AF. METHODS: We studied 364 patients (median age, 65 years) with persistent (n = 41) and paroxysmal (n = 323) AF undergoing successful first-session second-generation CBA with pre-ablation cardiac CTA. Three-vessel (3V)-PCATA was defined as the mean CT attenuation value of PCAT of all three major coronary arteries. Predictors of AF recurrence during follow-up were evaluated. RESULTS: AF recurrence after the 3-month blanking period was detected in 90 patients (24.7%) during the median follow-up of 26 (interquartile range, 19-42) months. AF recurrence was associated with prior stroke and statin use, NT-proBNP and high-sensitivity cardiac troponin-I levels, left ventricular dimension, left atrial volume index (LAVI), 3V-PCATA, and early AF recurrence during the blanking period. On multivariable Cox proportional hazard analysis, prior stroke (hazard ratio [HR], 2.208, 95% confidence interval [CI], 1.166-4.180, p = 0.015), LAVI (HR, 1.030, 95% CI, 1.010-1.051, p = 0.003), 3V-PCATA (HR, 1.034, 95% CI, 1.001-1.069, p = 0.046), and early AF recurrence (HR, 2.858, 95% CI, 1.855-4.405, p < 0.001) remained statistically significant. CONCLUSION: Pre-ablation CTA-derived 3V-PCATA, representing pericoronary inflammation, was an independent predictor of recurrence after first-session AF ablation using a second-generation cryoballoon. ADVANCES IN KNOWLEDGE: Assessment of 3V-PCATA may identify patients at high risk of AF recurrence after CBA for AF.

Circulatory dynamics changes are an additional predictor of successful pulmonary vein isolation during cryoballoon ablation.

The association between circulatory dynamics changes during cryoballoon applications and a successful pulmonary vein isolation (PVI) is unknown. Seventy atrial fibrillation patients who underwent PVI with 28-mm second-generation cryoballoons and single 3-min freezes were included. Intra-procedural parameters including circulatory dynamics changes during cryoapplications, were compared between 113 successful applications (30 left superior PVs[LSPVs], 30 left inferior PVs[LIPVs], 25 right superior PVs[RSPVs], and 28 right inferior PVs[RIPVs]) and 47 failed applications (10 LSPVs, 9 LIPVs, 8 RSPVs, and 20 RIPVs). In all individual PVs, lower nadir balloon temperatures (MinTemps) and longer thawing times (ThawTimes) significantly predicted a successful PVI. In addition, greater systolic blood pressure drops following releasing the PV occlusion (SBP-drops) significantly predicted a successful right PV PVI, and longer elapse times during SBP-drops significantly predicted a successful RIPV PVI. Composite parameters incorporating MinTemps and ThawTimes, SBP-drops, and ThawTimes showed the highest area under the curve to predict a successful left PV (0.876 for LSPVs, 0.851 for LIPVs) and right PV (0.927 for RSPVs, 0.980 for RIPVs) PVI, respectively. If the ThawTime (≥ 30 s) and SBP-drop (≤ - 21 mmHg) cutoff values were achieved for the RIPVs, the positive predictive value was 100%. In contrast, if both criteria were not achieved for the RIPVs, the negative predictive value was 100%. In the second-generation cryoballoon PVI, the MinTemp and ThawTime were significantly associated with acute success for all four PVs. In addition, SBP-drops further improved the accuracy of predicting a successful right PV PVI, especially of the RIPV.

Epicardial-endocardial breakthrough site ablation: Demonstration of alternative target for perimitral atrial tachycardia.

A 62-year-old man underwent the catheter ablation for persistent atrial tachycardia (AT) with a cycle length of 357 milliseconds. An ultrahigh resolution mapping revealed that this tachycardia was a clockwise perimitral AT despite the conduction was apparently blocked across the lateral mitral isthmus line both at the endocardium and within the coronary sinus. The AT was terminated by the single radiofrequency application at the site below the mitral isthmus line where the endocardial activation breakout was seen. This case suggests that the epicardial-endocardial conduction breakthrough site may be an alternative ablation target in a difficult ablation case of perimitral AT.

Utility of low-dose adenosine triphosphate sensitivity in slow-fast atrioventricular nodal reentrant tachycardia.

PURPOSE: Low-dose adenosine triphosphate (LD-ATP) is useful for diagnosing ATP-sensitive atrial tachycardia. However, the clinical implications of the sensitivity of LD-ATP in atrioventricular nodal reentrant tachycardia (AVNRT) still remain unknown. This study aimed to evaluate the mechanism of LD-ATP sensitivity in slow-fast AVNRT. METHODS: We estimated the sensitivity of LD-ATP in slow-fast AVNRT by a 2-4-mg ATP intravenous injection during the tachycardia. We evaluated the atrial-His (A-H) interval, tachycardia termination mode, prevalence of a lower common pathway (LCP), and successful ablation site in slow-fast AVNRT with LD-ATP sensitivity. LCPs were defined as His-atrial interval differences of at least 5 ms between that during ventricular pacing at the tachycardia cycle length and that during the tachycardia. RESULTS: Twenty-eight patients (mean age = 58 ± 11 years old, 18 females) with slow-fast AVNRT, who underwent catheter ablation of the antegrade slow pathway, were enrolled. Seventeen of 28 (61%) patients had LD-ATP sensitivity defined as termination of the tachycardia and/or a prolongation of the A-H interval of over 30 ms after an LD-ATP injection. The patients with LD-ATP sensitivity had a significantly higher prevalence of an LCP than those without (15/17 vs0/11, P < 0.0001). The successful ablation site in the LD-ATP sensitive group was significantly closer to the His bundle area than that in the LD-ATP nonsensitive group (13.3 ± 3.8 vs 20.5 ± 5.4 mm; distance to His bundle area in the left anterior oblique fluoroscopic view, P < 0.0001). CONCLUSIONS: LD-ATP sensitivity in slow-fast AVNRT may suggest the existence of an LCP. The successful ablation site in patients with LD-ATP sensitivity could be closer to the His bundle region.

A case of bidirectional conduction block within the superior vena cava induced by cryoballoon pulmonary vein isolation.

A 53-year-old male underwent a pulmonary vein isolation (PVI) of atrial fibrillation (AF) with a second-generation cryoballoon (CB). Although the patient maintained sinus rhythm after the PVI, a superior vena cava (SVC) fibrillation was recorded by a circular-multipolar-electrode catheter positioned inside the SVC that suggested conduction block between the right atrium (RA)-SVC connection. An adenosine triphosphate intravenous injection induced a dormant reconnection of the SVC myocardial sleeve and converted sinus rhythm to an AF rhythm. This case demonstrated that a CB application for the isolation of a right superior pulmonary vein could induce an electrical conduction block between the RA-SVC connection.

Characteristics of Phrenic Nerve Injury During Pulmonary Vein Isolation Using a 28-mm Second-Generation Cryoballoon and Short Freeze Strategy.

BACKGROUND: The reported incidence of phrenic nerve injury (PNI) varies owing to different definitions, balloon generations, balloon size, freezing regimen, and protective maneuvers. We evaluated the incidence, predictors, and outcome of PNI during cryoballoon pulmonary vein isolation in a large population. METHODS AND RESULTS: Five hundred fifty atrial fibrillation patients underwent pulmonary vein isolation using one 28-mm second-generation cryoballoon and single 3-minute freeze strategy under diaphragmatic compound motor action potential (CMAP) monitoring. A total of 34 (6.2%) patients experienced PNI during the right superior and inferior pulmonary vein ablation in 30 and 4 patients, respectively. Applications were interrupted using double-stop techniques after 136 [104-158] second applications, and a pulmonary vein isolation was already achieved in all but one case. The baseline CMAP amplitude and timing of deflation (CMAPdef) were 0.75±0.30 and 0.17±0.17 mV, respectively. Persistent atrial fibrillation, larger right superior pulmonary vein ostia, and deeper balloon positions were associated with higher incidences of PNI. The CMAPdef predicted a PNI recovery delay, and the best cutoff value for predicting PNI recovery by the next day was 0.20 mV (sensitivity 57.1%, specificity 100%). Among 6 patients undergoing second procedures 8.5 (6.7-15.0) months later, the right superior pulmonary vein was durable in 3 with >120 second applications. Despite active balloon deflation, no significant pulmonary vein stenosis was observed in 15 right superior pulmonary veins evaluated 6 (5-9) months later. No patients had symptoms, and the PNI recovered 1 day and 1 month postprocedure in 21 and 4 patients, respectively. CONCLUSIONS: PNI resulting from cryoballoon ablation was reversible. The double-stop technique is safe, and immediate active deflation following a CMAP decrease appears to be essential for faster PNI recovery.

Circulatory Dynamics During Pulmonary Vein Isolation Using the Second-Generation Cryoballoon.

BACKGROUND: Circulatory dynamics change during pulmonary vein (PV) isolation using cryoballoons. This study sought to investigate the circulatory dynamics during cryoballoon-based PV isolation procedures and the contributing factors. METHODS AND RESULTS: This study retrospectively included 35 atrial fibrillation patients who underwent PV isolation with 28-mm second-generation cryoballoons and single 3-minute freeze techniques. Blood pressures were continuously monitored via arterial lines. The left ventricular function was evaluated with intracardiac echocardiography throughout the procedure in 5 additional patients. Overall, 126 cryoapplications without interrupting freezing were analyzed. Systolic blood pressure (SBP) significantly increased during freezing (138.7±28.0 to 148.0±27.2 mm Hg, P<0.001) and sharply dropped (136.3±26.0 to 95.0±17.9 mm Hg, P<0.001) during a mean of 21.0±8.0 seconds after releasing the occlusion during thawing. In the multivariate analyses, the left PVs (P=0.008) and lower baseline SBP (P<0.001) correlated with a larger SBP rise, whereas a higher baseline SBP (P<0.001), left PVs (P=0.017), lower balloon nadir temperature (P=0.027), and female sex (P=0.045) correlated with larger SBP drops. These changes were similarly observed regardless of preprocedural atropine administration and the target PV order. PV occlusions without freezing exhibited no SBP change. PV antrum freezing without occlusions similarly increased the SBP, but the SBP drop was significantly smaller than that with occlusions (P<0.001). The SBP drop time-course paralleled the left ventricular ejection fraction increase (66.8±8.1% to 79.3±6.7%, P<0.001) and systemic vascular resistance index decrease (2667±1024 to 1937±513 dynes-sec/cm2 per m2, P=0.002). CONCLUSIONS: With second-generation cryoballoon-based PV isolation, SBP significantly increased during freezing owing to atrial tissue freezing and dropped sharply after releasing the occlusion, presumably because of the peripheral vascular resistance decrease mainly by circulating chilled blood.

Chromosome 4q25 variants and recurrence after second-generation cryoballoon ablation in patients with paroxysmal atrial fibrillation.

BACKGROUND: Chromosome 4q25 single-nucleotide polymorphisms (SNPs) are associated with atrial fibrillation (AF) recurrence after radiofrequency catheter ablation, however the underlying mechanism is unknown. Pulmonary vein (PV) reconnections are common post-radiofrequency ablation. We explored the pre-procedural parameters, including AF susceptibility SNPs, predicting the response to PV isolation (PVI) using second-generation cryoballoons. METHODS: One hundred fifty-seven paroxysmal AF patients undergoing PVI using second-generation cryoballoons and genetic testing were enrolled. The top 6 AF-associated Japanese ancestry SNPs were evaluated. Fourteen-day consecutive monitoring was performed to detect AF recurrences. RESULTS: Early recurrence of AF (ERAF) was detected in 74(47.1%) patients, and the AF-free survival at 12-months after single procedures was 72.1%. Cox's proportional models determined that higher pro-BNP values (hazard ratio [HR]=1.001; 95% confidence interval [CI]=1.000-1.001; p=0.003) and the rs1906617 risk allele (HR=2.440; 95% CI=1.062-5.605; p=0.035) were independently associated with ERAFs, and the rs1906617 risk allele (HR=4.339; 95% CI=1.044-18.028; p=0.043) was the sole factor significantly associated with AF recurrence. Second procedures were performed in 41 patients a median of 6.0[5.0-9.5] months later, and 42/162(25.9%) PVs were reconnected. Reconnections were similarly observed in rs1906617 risk allele carriers and wild-type patients. Risk allele carriers at rs1906617 were more likely to have non-PV foci, but did not reach statistical significance (10/35 vs. 0/6, p=0.132). CONCLUSIONS: AF risk alleles on chromosome 4q25 modulated the risk of AF recurrence after PVI using second-generation cryoballoons in patients with paroxysmal AF. Our study results suggested that non-PV foci might be the more likely mechanism of a high AF recurrence in chromosome 4q25 variant carriers.

Outcomes of Ventricular Tachycardia Ablation Using Percutaneous Left Ventricular Assist Devices.

BACKGROUND: Although percutaneous left ventricular assist devices (pLVADs) facilitate mapping and ablation of hemodynamically unstable ventricular tachycardia (VT), there is limited data whether clinical outcomes are improved. We sought to retrospectively compare the outcomes of patients undergoing scar-related VT ablation with and without pLVAD support. METHODS AND RESULTS: The study population comprised 194 patients (109 pLVAD and 85 non-pLVAD). The pLVAD group more often had dilated cardiomyopathy (33% versus 13%; P=0.001), New York Heart Association heart failure class ≥III (51% versus 25%; P<0.001), lower left ventricular ejection fractions (26±10% versus 39±16%; P<0.001), and electrical storm (49% versus 34%; P=0.04). Procedure times (422±112 versus 330±92 minutes; P<0.001), postablation VT inducibility (20% versus 7%; P=0.02), and length of subsequent hospitalization (median 6 versus 4 days; P=0.001) were all higher in the pLVAD group. During median follow-up of 215 days, the primary end point (recurrent VT, heart transplantation, or death) occurred in 36% of the pLVAD versus 26% of the non-pLVAD groups (P=0.14). After propensity matching for differences between groups, no differences were seen between groups for both acute procedural outcomes and the primary end point. CONCLUSIONS: In this large single-center scar-related VT ablation experience, despite the worse clinical status of the patients selected for pLVAD support, clinical outcomes were better than expected and were similar to healthier patients not receiving hemodynamic support. Patients with dilated cardiomyopathy presenting with electrical storm, advanced heart failure, and severe left ventricular dysfunction most frequently received hemodynamic support during VT ablation.

Validation of electrical ostial pulmonary vein isolation verified with a spiral inner lumen mapping catheter during second-generation cryoballoon ablation.

BACKGROUND: Achieve catheters are cryoballoon guidewires that enable pulmonary vein (PV) potential mapping. The single catheter approach in conjunction with the Achieve catheter is currently standard practice in second-generation cryoballoon ablation, yet circumferential mapping catheters are the gold standard for evaluating PV isolation (PVI). The study sought to validate the ostial PVI verified by an Achieve catheter alone. METHODS: One hundred fifty-one paroxysmal atrial fibrillation patients undergoing PVI using exclusively 28-mm second-generation cryoballoons were enrolled. PV recordings were analyzed during (real-time recordings) and after cryoballoon applications with 20-mm Achieve mapping catheters, and subsequently validated by 20-mm conventional circumferential mapping catheters. RESULTS: Out of 596 PVs, 576 (96.6%) were isolated using cryoballoons, and 20 required touch-up ablation. PVI was verified during cryoballoon applications with real-time monitoring in 299, and after applications in 280 PVs by Achieve catheters alone. The time-to-isolation was 27.2 ± 22.0 seconds. Validation with standard circumferential mapping catheters confirmed ostial PVIs in 296 of 299 (99.0%) PVs that real-time PVI was obtained during applications, and in 242 of 280 (86.5%) PVs that PV activities were not visible during applications and PVI was verified after the applications. The accuracy of ostial PVIs with Achieve catheters in PVs without obtaining real-time PV recordings was 40/47 (85.1%), 58/65 (89.2%), 77/79 (97.5%), 61/81 (75.3%), and 6/8 (75.0%) in left superior, left inferior, right superior, right inferior, and left common PVs, respectively. CONCLUSIONS: In second-generation 28-mm cryoballoon ablation, verification of ostial PVIs using Achieve mapping catheters alone might not be sufficient to accurately confirm an ostial PVI when real-time PVI was not obtained.

Electrical superior vena cava isolation using a novel pace-and-ablate technique under diaphragmatic electromyography monitoring.

BACKGROUND: Diaphragmatic compound motor action potential (CMAP) amplitude monitoring is a standard technique to anticipate phrenic nerve injury during cryoballoon ablation. OBJECTIVE: The purpose of this study was to evaluate the feasibility of a novel superior vena cava isolation (SVCI) technique using simultaneous pacing and ablation through the tip of a single mapping/ablation catheter. METHODS: Fifty-four patients with atrial fibrillation were included. Radiofrequency energy was delivered point by point uniformly for 20 seconds with a power of 20 W until achieving SVCI. Diaphragmatic CMAPs were obtained from modified surface electrodes by high-output pacing from the mapping/ablation catheter throughout the procedure (pace-and-ablate group). Applications were interrupted if CMAP amplitudes significantly decreased without fluoroscopy. The data were compared with those of the 54 patients undergoing conventional SVCI (conventional group). RESULTS: Successful SVCI procedures were achieved in all with a mean of 10.3 ± 2.9 applications. In total, among 559 ablation sites, CMAPs were recorded at 95 (17.0%) with baseline amplitudes of 0.45 ± 0.23 mV. In 10 patients (18.5%), isolation was achieved without any radiofrequency deliveries at CMAP-recorded sites. Among the 95 applications, 6 (6.3%) were interrupted because of CMAP amplitude reductions. At the remaining 88 sites, 20-second radiofrequency applications were delivered without any amplitude decrease (from 0.45 ± 0.21 to 0.46 ± 0.23 mV; P = .885). Phrenic nerve injury occurred in 1 patient in the pace-and-ablate group, which recovered 3 months later, and in 3 conventional group patients, of whom 1 recovered 1 month later (P = .308). The total procedure time tended to be shorter (14.5 ± 6.3 minutes vs 16.7 ± 9.2 minutes; P = .153) and fluoroscopy time significantly shorter (3.9 ± 3.0 minutes vs 6.7 ± 5.7 minutes, P = .002) in the pace-and-ablate group than in the conventional group. CONCLUSION: A novel and simple pace-and-ablate technique under diaphragmatic electromyography monitoring might be feasible for an electrical SVCI.

The relationship between oesophageal heating during left atrial posterior wall ablation and the durability of pulmonary vein isolation.

AIM: During ablation of the posterior wall (PW), luminal oesophageal temperature elevation (OTE) prompts attenuation of radiofrequency (RF) energy delivery to minimize oesophageal injury. This strategy on lesion efficacy is unknown. The goal of this study was to analyse the relationship between OTE and pulmonary vein reconnection (PVR). METHODS AND RESULTS: During the index antral pulmonary vein (PV) isolation procedure with an irrigated RF ablation catheter, OTE was detected with a multisensor oesophageal temperature probe. Posterior wall ablation did not exceed 25 W and was terminated when the temperature was ≥38.5°C. Patients undergoing redo procedures (n = 142) were studied for PW sites of PVR along 4 segments: left and right superior, and left and right inferior. Pulmonary vein reconnections had occurred in 51 of the 142 patients (36%), in 58 of 284 PV pairs (20%). Among these 58 reconnected pairs, 83% (n = 48) were along the PW. Oesophageal temperature elevation had occurred in 30 patients (59%). No difference in characteristics was seen between the patients with OTE (n = 30) and those without (n = 21). For superior segments, there was no interaction between the presence or absence of OTE and PVR. For inferior segments, there were more PVRs in the group with OTE: for the right-inferior segment, the PVR rate was 72% for OTE cases vs. 42% without (P = 0.04), and for the left-inferior segment, the PVR rate was 44% for OTE cases vs. 22.9% without (P = 0.12). CONCLUSION: Pulmonary vein reconnections are predominantly posteriorly located. Along the right- and left-inferior PW segments, there was an association with elevated oesophageal temperature during the index procedure.

Prevalence and clinical outcome of phrenic nerve injury during superior vena cava isolation and circumferential pulmonary vein antrum isolation using radiofrequency energy.

BACKGROUND: Phrenic nerve injury (PNI) is recognized as an important complication during atrial fibrillation ablation. This study aimed to investigate the incidence and outcome of PNI during superior vena cava isolation (SVCI) and circumferential pulmonary vein isolation (CPVI) using radiofrequency (RF) energy and the factors associated with its occurrence. METHODS AND RESULTS: Five hundred sixty-seven consecutive patients who underwent SVCI after CPVI without substrate modification who completed a 12-month follow-up were retrospectively analyzed. Point-by-point RF applications were applied with maximum energy settings of 35 W and 30 seconds for the SVCI. In the former 210 patients, sites where pacing captured the PN were avoided whenever possible; however, the maximum power was 35 W. In the latter 357 patients, RF energy was delivered regardless of PN capture; however, the power at PN capture sites was limited to 10 W during continuous diaphragmatic movement monitoring on fluoroscopy. Circumferential pulmonary vein isolation and SVCI were successfully achieved in all. Twelve patients (2.1%) had PNI during SVCI but not during CPVI. Phrenic nerve injury completely recovered in all patients a median of 8.0 months after the procedure. The prevalence was higher in the former period (3.8% vs 1.1%; P = .03). A multivariate logistic regression analysis revealed that the study period (odds ratio 3.546; 95% CI 1.051-11.965; P = .041) was the sole independent predictor for identifying patients with PNI during SVCI. CONCLUSIONS: Phrenic nerve injury occurred in 2.1% of the patients. All occurred during SVCI but not during contemporary CPVI. Energy titration and continuous diaphragmatic movement monitoring significantly decreased the incidence during SVCI.

Incidences of esophageal injury during esophageal temperature monitoring: a comparative study of a multi-thermocouple temperature probe and a deflectable temperature probe in atrial fibrillation ablation.

PURPOSE: The study aim was to compare the incidence of esophageal injuries between different temperature probes in the monitoring of esophageal temperature during atrial fibrillation (AF) ablation. METHODS: One hundred patients with drug-resistant AF were prospectively and randomly assigned into two groups according to the esophageal temperature probe used: the multi-thermocouple probe group (n = 50) and the deflectable temperature probe group (n = 50). Extensive pulmonary vein (PV) isolation was performed with a 3.5-mm open irrigated tip ablation catheter by using a radiofrequency (RF) power of 25-30 W. In both groups, the esophageal temperature thermocouple was placed on the area of the esophagus adjacent to the ablation site. When the esophageal temperature reached 42 °C, the RF energy delivery was stopped. Esophageal endoscopy was performed 1 day after the catheter ablation. RESULTS: No differences existed between the two groups in terms of clinical background and various parameters related to the catheter ablation, including RF delivery time and number of RF deliveries at an esophageal temperature of >42 °C. Esophageal lesions, such as esophagitis and esophageal ulcers, occurred in 10/50 (20 %) and 15/50 (30 %) patients in the multi-thermocouple and deflectable temperature probe groups, respectively (P = 0.25). Most lesions were mild to moderate injuries, and all were cured using conservative treatment. CONCLUSION: The incidence of esophageal injury was almost equal between the multi-thermocouple temperature probe and the deflectable temperature probe during esophageal temperature monitoring. Most of the esophageal lesions that developed during esophageal temperature monitoring were mild to moderate and reversible.

Role of arrhythmogenic superior vena cava on atrial fibrillation.

BACKGROUND: It is well known that superior vena cava (SVC) is one of the important non-pulmonary vein (PV) foci of atrial fibrillation (AF). However, little is known regarding the role of arrhythmogenic SVC in AF. METHODS AND RESULTS: Among 1,425 patients who underwent AF ablation in 2 centers, PV antrum isolation was performed in all and SVC isolation was added in 74 (5.2%) patients with arrhythmogenic SVC (58 ± 10 years; 54 males) when the latter was identified as an AF source. The arrhythmogenicity was identified at the 1st, 2nd, and 3rd procedures in 62 (83.8%), 7 (9.5%), and 5 (6.7%) patients, respectively. In 7 (9.5%), 26 (35.1%), and 14 (18.9%) patients, it was identified following adenosine injection, isoproterenol infusion, and electrical cardioversion, respectively. SVC triggering AF was identified in 58 out of 74 (78.4%) patients. In this subset, AF initiated from SVC; however, AF cycle length was longer in SVC than in the right atrium once AF persisted, which suggested its role as an initiator. In 24 (32.4%) patients following the isolation of SVC, AF terminated or converted to atrial flutter and/or confined SVC tachycardia/fibrillation was observed, which suggested its role as a perpetuator. Sixty-four (86.5%) of 74 patients were free from any atrial tachyarrhythmias without antiarrhythmic drugs mean 12.1 ± 9.4 months after the last ablation procedure (mean 1.38 procedures/patient). CONCLUSIONS: In a subset of patients, SVC plays a role in AF not only as an initiator/trigger but also as a driver/perpetuator.

Impact of low-dose dipyridamole injection on adenosine test after pulmonary vein isolation.

BACKGROUND: Dipyridamole increases the levels of extracellular adenosine. The study investigates the impact of low-dose intravenous dipyridamole on adenosine test after pulmonary vein (PV) isolation (PVI). METHODS AND RESULTS: This prospective study included 12 paroxysmal atrial fibrillation (AF) patients (61 ± 12 years; nine men) who underwent PVI at the first procedure. Transient PV reconnection was provoked by adenosine test in 4/48 PVs. In 44 PVs without reconnection, intravenous infusion of low-dose (10 mg) dipyridamole preceded the adenosine test. Additional six patients (PVs) with transient dormant conduction were included. Among the total 10 PVs with transient reconnection, it was eliminated by radiofrequency (RF) application(s) until no dormant conduction was exposed by adenosine test(s) in five PVs. Then, dipyridamole potentiated adenosine test was undertaken to provoke dormant conduction (group 1). In the remaining five PVs, dipyridamole potentiated adenosine test was followed by RF elimination of conduction gap and repeat adenosine test to confirm complete elimination (group 2). Low-dose dipyridamole prolonged the duration of adenosine-induced atrioventricular block without vasodilatatory hypotension. There was no evidence of reconnection in 44 PVs without dormant conduction and in group 1 wherein transient reconnection was eliminated by 4.8 ± 3.2 RF applications in 8.8 ± 3.0 minutes and adenosine injected 3.1 ± 1.8 times. In group 2, dipyridamole plus adenosine test revealed the same dormant conduction that persisted longer than during adenosine alone. It was eliminated by single RF application in 3.4 ± 0.9 minutes, and adenosine was injected once. CONCLUSIONS: Low-dose dipyridamole safely prolongs the electrophysiological effects of adenosine test without provoking additional PV reconnection. This allows sustained visualization and facilitates complete RF elimination of the electrical conduction gap.

Clinical impact of adenosine triphosphate injection on arrhythmogenic superior vena cava in the context of atrial fibrillation ablation.

BACKGROUND: Superior vena cava (SVC) is an infrequent yet an important source of atrial fibrillation. The clinical impact of ATP injection on arrhythmogenic SVC has not been evaluated. METHODS AND RESULTS: A total of 43 patients (59±11 years; men, 32) who underwent ATP test for arrhythmogenic SVC after the electric isolation at either initial procedure or repeat procedure were included. Pulmonary vein antrum isolation was performed at index procedure in all patients. SVC was isolated after identifying the arrhythmogenicity at index and repeat atrial fibrillation ablation procedure in 34 (79.1%) and 9 (20.9%) patients, respectively. Atrial fibrillation originated from the SVC spontaneously and under isoproterenol infusion in 30 (75.0%) patients, and immediately after ATP injection in 10 (25.0%) patients. Tachycardia persistently confined to SVC was recorded after electric isolation in 13 (30.2%) patients. SVC reconnection was provoked by ATP test in 7 of 36 (19.4%) patients at acute phase. At median 4.0 (2.25-7.5) months after SVC isolation, reconnection was observed in 12 of 15 (80.0%) patients at repeat procedure. Among 12 patients with reconnection at baseline, SVC reconnection was provoked by ATP test after reisolation in 1 (8.3%) patient. Among 3 patients without SVC reconnection at baseline, reconnection was provoked by ATP test at chronic phase in 1 patient. CONCLUSIONS: Dormant conduction between an arrhythmogenic SVC and the right atrium can be exposed by ATP administration both immediately and late after isolation, potentially facilitating detection and ablation for isolation.

Clinical utility of adenosine-infusion test at a repeat atrial fibrillation ablation procedure.

BACKGROUND: The majority of patients with recurrence of arrhythmia after the initial atrial fibrillation (AF) ablation procedure have resumption of pulmonary vein (PV) conduction. Adenosine-infusion test after PV isolation identifies acute dormant PV conduction during the index procedure. OBJECTIVE: To evaluate the utility of adenosine-infusion test at a repeat AF ablation procedure. METHODS: This study included 50 consecutive patients (38 men; mean age 65 ± 9 years) who underwent second ablation procedure for recurrent atrial tachyarrhythmia(s). At the index procedure, which was undertaken for paroxysmal AF, all patients underwent PV isolation and 48 of 50 (96%) underwent superior vena cava (SVC) isolation followed by adenosine infusion. PV and SVC were reisolated-if found reconnected-at the start of the second procedure. Thereafter, adenosine-infusion test was undertaken for all PVs in all patients. RESULTS: At the index procedure, adenosine infusion revealed dormant PV conduction in 15 of 50 (30%) patients. At the second procedure, after 10 ± 10 months, PV and SVC reconnections were observed in 46 of 50 (92%) and 33 of 48 (68.8%) patients and they were reisolated. Subsequently, adenosine-infusion test revealed dormant PV conduction in 9 of 50 (18%) patients, including 3 of 50 (6%) who had no PV reconnection at the start of the procedure. In these 3 patients, transient AF resulted after adenosine infusion, and at mean 8.0 ± 3.4 months, they were free from any atrial arrhythmia after the elimination of dormant PV conduction alone. CONCLUSIONS: Adenosine-infusion test reveals dormant thoracic vein conduction associated with arrhythmia recurrence in the chronic phase after the initial PV isolation.