Characteristics of tissue temperature during ablation with THERMOCOOL SMARTTOUCH SF versus TactiCath versus QDOT MICRO catheters (Qmode and Qmode+): An in vivo porcine study.

INTRODUCTION: High-power short-duration (HPSD) ablation at 50 W, guided by ablation index (AI) or lesion size index (LSI), and a 90 W/4 s very HSPD (vHPSD) setting are available for atrial fibrillation (AF) treatment. Yet, tissue temperatures during ablation with different catheters around venoatrial junction and collateral tissues remain unclear. METHODS: In this porcine study, we surgically implanted thermocouples on the epicardium near the superior vena cava (SVC), right pulmonary vein, and esophagus close to the inferior vena cava. We then compared tissue temperatures during 50W-HPSD guided by AI 400 or LSI 5.0, and 90 W/4 s-vHPSD ablation using THERMOCOOL SMARTTOUCH SF (STSF), TactiCath ablation catheter, sensor enabled (TacthCath), and QDOT MICRO (Qmode and Qmode+ settings) catheters. RESULTS: STSF produced the highest maximum tissue temperature (Tmax ), followed by TactiCath, and QDOT MICRO in Qmode and Qmode+ (62.7 ± 12.5°C, 58.0 ± 10.1°C, 50.0 ± 12.1°C, and 49.2 ± 8.4°C, respectively; p = .005), achieving effective transmural lesions. Time to lethal tissue temperature ≥50°C (t-T ≥ 50°C) was fastest in Qmode+, followed by TacthCath, STSF, and Qmode (4.3 ± 2.5, 6.4 ± 1.9, 7.1 ± 2.8, and 7.7 ± 3.1 s, respectively; p < .001). The catheter tip-to-thermocouple distance for lethal temperature (indicating lesion depth) from receiver operating characteristic curve analysis was deepest in STSF at 5.2 mm, followed by Qmode at 4.3 mm, Qmode+ at 3.1 mm, and TactiCath at 2.8 mm. Ablation at the SVC near the phrenic nerve led to sudden injury at t-T ≥ 50°C in all four settings. The esophageal adventitia injury was least deep with Qmode+ ablation (0.4 ± 0.1 vs. 0.8 ± 0.4 mm for Qmode, 0.9 ± 0.3 mm for TactiCath, and 1.1 ± 0.5 mm for STSF, respectively; p = .005), correlating with Tmax . CONCLUSION: This study revealed distinct tissue temperature patterns during HSPD and vHPSD ablations with the three catheters, affecting lesion effectiveness and collateral damage based on Tmax and/or t-T ≥ 50°C. These findings provide key insights into the safety and efficacy of AF ablation with these four settings.

Complete free wall isolation of arrhythmogenic persistent left superior vena cava.

INTRODUCTION: Persistent left superior vena cava (PLSVC) is one of the major sources of triggers and drivers of atrial fibrillation (AF). There has been no established PLSVC ablation procedure to eliminate the arrhythmogenicity along the entire length of PLSVC. METHODS AND RESULTS: A 70-year-old woman with a history of two previous catheter ablations for AF, mitral valvuloplasty, and an unroofed coronary sinus-type atrial septal defect closure underwent the redo AF ablations. The AF trigger and driver were identified within the patient's enlarged PLSVC. The AF was treated by complete PLSVC free wall isolation. CONCLUSION: Complete PLSVC free wall isolation may be an effective ablation method to eliminate the arrhythmogenicity along the entire length of the PLSVC.

Combined approach of high-power and very high-power, short-duration ablation in superior vena cava isolation.

INTRODUCTION: The effectiveness and safety of 50 W, high-power, short-duration (HPSD) ablation in superior vena cava isolation (SVCI) for patients with atrial fibrillation (AF) have been reported. However, the acute outcomes of SVCI combined with 90 W/4 s, very high-power, short-duration (vHPSD) ablation remain unknown. In this study, we aimed to investigate a novel approach that combines 50 W-HPSD and 90 W/4 s-vHPSD ablation in SVCI and to elucidate the characteristics, outcomes, and safety of this approach by comparing SVCI with conventional ablation index (AI)-guided middle-power, middle-duration (MPMD) ablation. METHODS: Overall, 126 patients who underwent AF ablation with SVCI using the QDOT MICROTM catheter were retrospectively reviewed; one group underwent SVCI with a combined approach of HPSD and vHPSD ablation (50 W/90 W group, n = 73) and another group underwent AI-guided MPMD ablation (30-40 W group, n = 53). This study compared the procedural details, radiofrequency (RF) ablation profiles, and complications. The RF settings used in the 50 W/90 W group were 50 W/7 s for the lateral segment close to the phrenic nerve and 90 W/4 s for the nonlateral segment. RESULTS: The 50 W/90 W group required a significantly shorter procedural time (3.2 vs. 5.9 min, p < .001), shorter RF duration (42.0 vs. 162.0 s, p < .001), and lower RF energy (2834 vs. 5480 J, p < .001) than the 30-40 W group. Procedural success, first-pass SVCI, number of RF applications, and SVC reconnection after isoproterenol loading were comparable between the groups. The maximum tip-electrode temperature of the multi-thermocouple system was significantly higher in the 50 W/90 W group than in the 30-40 W group (50.0°C vs. 47.0°C, p < .001). No complications, such as phrenic nerve injury or bleeding requiring transfusion, were observed in either group. CONCLUSIONS: The combined approach of 50 W/7 s-HPSD and 90 W/4 s-vHPSD ablation resulted in successful and safe SVCI with shorter procedural time, shorter RF duration, and lower RF energy.

Distance-dependent neuromodulation effect during thermal ablation for atrial fibrillation.

INTRODUCTION: Thermal atrial fibrillation (AF) ablation exerts an additive treatment effect on the cardiac autonomic nervous system (CANS). This effect is mainly reported during ablation of the right superior pulmonary vein (RSPV), modulating the right anterior ganglionated plexus (RAGP), which contains parasympathetic innervation to the sinoatrial node in the epicardial fat pad between RSPV and superior vena cava (SVC). However, a variable response to neuromodulation after ablation is observed, with little to no effect in some patients. Our objective was to assess clinical and anatomic predictors of thermal ablation-induced CANS changes, as assessed via variations in heart rate (HR) postablation. METHODS: Consecutive paroxysmal AF patients undergoing first-time PV isolation by the cryoballoon (CB) or radiofrequency balloon (RFB) within a 12-month time frame and with preprocedural cardiac computed tomography (CT), were evaluated. Preablation and 24-h postablation electrocardiograms in sinus rhythm were collected and analyzed to assess HR. Anatomic evaluation by CT included the measurement of the shortest distance between the SVC and RSPV ostium (RSPV-SVC distance). RESULTS: A total of 97 patients (CB, n = 50 vs. RFB, n = 47) were included, with similar baseline characteristics between both groups. A significant HR increase postablation (ΔHR ≥ 15 bpm) occurred in a total of 37 patients (38.1%), without difference in number of patients between both thermal ablation technologies (CB, 19 [51%]), RFB, 18 [49%]). Independent predictors for increased HR were RSPV-SVC distance (odds ratio [OR]: 0.49, CI: 0.34-0.71, p value < .001), and age (OR: 0.94, CI: 0.89-0.98, p value = .003). CONCLUSIONS: Thermal balloon-based PV isolation influences the CANS through its effect on the RAGP, especially in younger patients and patients with shorter RSPV-SVC distance.

Role of electroanatomical mapping-guided superior vena cava isolation in paroxysmal atrial fibrillation patients without provoked superior vena cava triggers: a randomized controlled study.

AIMS: Data about whether empirical superior vena cava (SVC) isolation (SVCI) improves the success rate of paroxysmal atrial fibrillation (PAF) are conflicting. This study sought to first investigate the characteristics of SVC-triggered atrial fibrillation and secondly investigate the impact of electroanatomical mapping-guided SVCI, in addition to circumferential pulmonary vein isolation (CPVI), on the outcome of PAF ablation in the absence of provoked SVC triggers. METHODS AND RESULTS: A total of 130 patients undergoing PAF ablation underwent electrophysiological studies before ablation. In patients for whom SVC triggers were identified, SVCI was performed in addition to CPVI. Patients without provoked SVC triggers were randomized in a 1:1 ratio to CPVI plus SVCI or CPVI only. The primary endpoint was freedom from any documented atrial tachyarrhythmias lasting over 30 s after a 3-month blanking period without anti-arrhythmic drugs at 12 months after ablation. Superior vena cava triggers were identified in 30 (23.1%) patients with PAF. At 12 months, 93.3% of those with provoked SVC triggers who underwent CPVI plus SVCI were free from atrial tachyarrhythmias. In patients without provoked SVC triggers, SVCI, in addition to CPVI, did not increase freedom from atrial tachyarrhythmias (87.9 vs. 79.6%, log-rank P = 0.28). CONCLUSION: Electroanatomical mapping-guided SVCI, in addition to CPVI, did not increase the success rate of PAF ablation in patients who had no identifiable SVC triggers. REGISTRATION: ChineseClinicalTrials.gov: ChiCTR2000034532.

Superior vena cava isolation using a pentaspline pulsed-field ablation catheter: feasibility and safety in patients undergoing atrial fibrillation catheter ablation.

AIMS: Superior vena cava (SVC) isolation during atrial fibrillation catheter ablation is limited by the risk of collateral damage to the sinus node and/or the phrenic nerve. Due to its tissue-specificity, we hypothesized the feasibility and safety of pulsed-field ablation (PFA)-based SVC isolation. METHODS AND RESULTS: One hundred and five consecutive patients undergoing PFA-based AF catheter ablation were prospectively included. After pulmonary vein isolation (±posterior wall isolation and electrical cardioversion), SVC isolation was performed using a standardized workflow. Acute SVC isolation was achieved in 105/105 (100%) patients after 6 ± 1 applications. Transient phrenic nerve stunning occurred in 67/105 (64%) patients but without phrenic nerve palsy at the end of the procedure and at hospital discharge. Transient high-degree sinus node dysfunction occurred in 5/105 (4.7%) patients, with no recurrence at the end of the procedure and until discharge. At the 3-month follow-up visit, no complication occurred. CONCLUSION: SVC isolation using a pentaspline PFA catheter is feasible and safe.

A rare case of modified superior vena cava isolation by using the ultra-high-resolution mapping system.

We report a case of atrial fibrillation (AF) recurrence after pulmonary vein isolation, which patient had AF trigger in the superior vena cava (SVC) near the sinus node (SN). The ultra-high-resolution mapping revealed that SN located within the SVC and the atrial activation from the SN to SVC propagated in both septal and lateral direction, then upward with circumventing the spontaneous conduction block identified just above and lateral SN (upper hemisphere). We successfully isolated SVC including the ectopic origin at the same level as the SN by utilizing the spontaneous conduction block line around the SN without any complication.

Utility of covered stents as a bypass for the treatment of central venous occlusion: a case report.

BACKGROUND: Central venous occlusion (CVO) is difficult to treat with percutaneous transluminal angioplasty because the guidewire cannot pass through the occluded segments. In this study, we devised a new method for establishing an extra-anatomic bypass between the right subclavian vein and the superior vena cava via a covered stent to treat whole-segment occlusion of the right brachiocephalic vein (BCV) with calcification. CASE PRESENTATION: We present the case of a 58-year-old female patient who complained of right arm swelling present for 1.5 years. Twelve years prior, the patient began hemodialysis because chronic glomerulonephritis had progressed to end-stage renal disease. During the first 3 years, a right internal jugular vein (IJV)-tunneled cuffed catheter was used as the dialysis access, and the catheter was replaced once. A left arteriovenous fistula (AVF) was subsequently established. Owing to occlusion of the left AVF, a new fistula was established on the right upper extremity 1.5 years prior to this visit. Angiography of the right upper extremity revealed complete occlusion of the right BCV and IJV with calcification. Because of the failure to pass the guidewire across the lesion, we established an extra-anatomic bypass between the right subclavian vein and the superior vena cava with a covered stent. Angiography confirmed the patency of whole vascular access system. After 3 months of follow-up, the patient's AVF function and the bypass patency were satisfactory. CONCLUSIONS: As a new alternative for the treatment of long, angled CVO with or without calcification, a covered stent can be used to establish an extravascular bypass between central veins.

[Long-term Outcomes of the Maze Procedure Omitting the Ablation Line to The Superior Vena Cava].

OBJECTIVE: In an effort to avoid postoperative sick sinus syndrome( SSS), we omit the ablation line to the superior vena cava( SVC) in the Cox-mazeⅢ lesion set. We report the long-term outcomes, including the freedom from SSS. METHODS: We studied 102 patients who underwent bi-atrial maze procedure for persistent atrial fibrillation (Af) from 2009 through 2023. Bipolar radio frequency ablation or cryoablation was used except for right-side atriotomy and right atriotomy. Cryoablation was used for atrioventricular annulus. The patient age was 68±9.4. Duration of Af was 3.4±6.5 years (unknown 9 cases). The amplitude of f-wave in V1 was 0.182±0.095 mV and it was<0.1 mV in 19 (18.6%). Diameter of the left atrium was 50±8.9 mm, and left atrial volume index was 89±37 ml/m2. Ninety-one (89.2%) patients underwent concomitant mitral valve surgery. RESULTS: Survival rate was 99% at 1 year and 96% at 5 years. Freedom from Af was 92% at 1 year and 88% at 5 years. Freedom from permanent pacemaker implantation (PPI) was 87% at 1 year and 83% at 5 years. CONCLUSIONS: Defibrillation rate and the incidence of PPI was comparable to those in previous reports after standard Cox-mazeⅢ. SSS after maze for persistent Af seem due to patient.

Optimization of superior vena cava isolation with aid of ablation index guidance.

INTRODUCTION: To investigate the optimal range of quantitative ablation index (AI) value during superior vena cava (SVC) electrical isolation by radiofrequency catheter ablation (RFCA). METHODS: First, in a development cohort of patients with atrial fibrillation (AF), the RFCA with 40 W was performed to complete SVC isolation guided by the conduction breakthrough point from the right atrium to SVC. Then, the range of AI value was calculated by offline analysis on different segments of SVC. Lastly, for the validation of AF patients, the safety and effectiveness of SVC isolation with the optimized target range of AI value were evaluated with an additional adenosine test. RESULTS: A total of 101 patients with AF were included in the study (44 patients in the development cohort/57 in the validation cohort). The segmental ablation strategy was applied in 70% of the patients. According to the offline analysis of the AI values in the development cohort, the target AI value range was set as 350-400. The success rate of SVC isolation in the validation cohort was significantly higher than that in the exploration cohort (100% vs. 90.9%, p = .02), and no complications occurred in the exploration cohort. During the adenosine test, the recovery rate of electrical conduction in SVC was significantly lower than that in the pulmonary vein (3.5% vs. 17.5%). CONCLUSION: The target AI value with a range from 350 to 400 is safe and effective for high-power RFCA to complete SVC isolation.

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.

Pulsed-field-ablation for the treatment of atrial fibrillation in patients with congenital anomalies of cardiac veins.

INTRODUCTION: Anomalous cardiac veins are not rare and pulmonary vein (PV) isolation for atrial fibrillation (AF) treatment should include these veins. Pulsed-field ablation (PFA) is a novel technology for AF ablation with excellent efficacy and safety profile. In this case series, we describe our first experience of isolation of anomalous cardiac veins using PFA in patients with AF. METHODS: We report a series of patients with congenital anomalies of the cardiac veins and AF, treated with PFA. All patients underwent cardiac computed tomography for procedural planning. RESULTS: We included five patients (four males). Anomalous cardiac veins included a connection of a left common ostium to the coronary sinus, a partial and complete drainage of the right superior PV into the superior vena cava (SVC) with and without additional atrial septal defect, a persistent left SVC and an anomalous posterior PV. All anomalous PVs were isolated using PFA. No phrenic nerve palsy or other complications occurred. PFA of an abnormal right superior PV draining into the distal SVC was possible without affecting the sinus node. After a median of 4 months, four patients were free of recurrence. One patient had recurrent AF and perimitral reentry tachycardia, probably facilitated by PFA in the mitral isthmus region during isolation of an anomalous connection of the left common ostium to the coronary sinus. CONCLUSIONS: Using systematic preprocedural imaging and three-dimensional-electroanatomic mapping, the currently available PFA system seems well suited, efficient, and versatile for the treatment of AF in patients with anomalous cardiac veins.

3D mapping of phrenic nerve course for radiofrequency pulmonary vein isolation.

INTRODUCTION: Phrenic nerve (PN) injury is a rare but severe complication of radiofrequency (RF) pulmonary vein isolation (PVI). The objective of this study was to characterize the typical intracardiac course of the PN with a three-dimensional electroanatomic mapping system, to quantify the need for modification of the ablation trajectory to avoid delivering an ablation lesion on sites with PN capture, and to identify very circumscribed areas of common PNC on the routine ablation trajectory of a RF-PVI, allowing fast and effective PN screening for everyday usage. METHODS: We enrolled 137 consecutive patients (63 ± 9 years, 64% men) undergoing PVI. A detailed high output (20 mA) pace-mapping protocol was performed in the right (RA) and left atrium (LA) and adjacent vasculature. RESULTS: The right PN was most commonly captured in the superior vena cava at a lateral (50%) or posterolateral (23%) position before descending along the RA either straight (29%) or with a posterolateral bend (20%). In the LA, beginning deep within the right superior pulmonary vein (RSPV), the right PN is most frequently detectable anterolateral (31%), then descends to the lateral proximal RSPV (23%), and further towards the lateral antral region (15%) onto the medial LA wall (12%). To avoid delivering an ablation lesion on sites with PN capture, modification of ablation trajectory was necessary in 23% of cases, most commonly in the lateral RSPV antrum (81%). No PN injury occurred. CONCLUSION: PN mapping frequently reveals the close proximity of the PN to the ablation trajectory during PVI, particularly in the lateral RSPV antrum. Routine PN pacing should be considered during RF PVI procedures.

Comparison of non-laser and laser transvenous lead extraction: a systematic review and meta-analysis.

AIMS: Transvenous lead extraction (TLE) is performed using non-laser and laser techniques with overall high efficacy and safety. Variation in outcomes between the two approaches does exist with limited comparative evidence in the literature. We sought to compare non-laser and laser TLE in a meta-analysis. METHODS AND RESULTS: We searched Medline, Embase, Scopus, ClinicalTrials.gov, and CENTRAL databases for TLE studies published between 1991 and 2021. From the included 68 studies, safety and efficacy data were carefully evaluated and extracted. Aggregated cases of outcomes were used to calculate odds ratio (OR), and pooled rates were synthesized from eligible studies to compare non-laser and laser techniques. Subgroup comparison of rotational tool and laser extraction was also performed. Non-laser in comparison with laser had lower procedural mortality (pooled rate 0% vs. 0.1%, P < 0.01), major complications (pooled rate 0.7% vs. 1.7%, P < 0.01), and superior vena cava (SVC) injury (pooled rate 0% vs. 0.5%, P < 0.001), with higher complete success (pooled rate 96.5% vs. 93.8%, P < 0.01). Non-laser comparatively to laser was more likely to achieve clinical [OR 2.16 (1.77-2.63), P < 0.01] and complete [OR 1.87 (1.69-2.08), P < 0.01] success, with a lower procedural mortality risk [OR 1.6 (1.02-2.5), P < 0.05]. In the subgroup analysis, rotational tool compared with laser achieved greater complete success (pooled rate 97.4% vs. 95%, P < 0.01) with lower SVC injury (pooled rate 0% vs. 0.7%, P < 0.01). CONCLUSION: Non-laser TLE is associated with a better safety and efficacy profile when compared with laser methods. There is a greater risk of SVC injury associated with laser sheath extraction.

Balloon surface temperature-controlled ablation using a second-generation radiofrequency HotBalloon: an in vivo feasibility study.

AIMS: The first-generation radiofrequency HotBalloon (RHB) is a size-adjustable single-shot device used in atrial fibrillation. The energy output is determined by its central temperature and not by its balloon surface temperature (BST), thus limiting its efficacy and safety. Therefore, a second-generation RHB was developed to monitor BST and enable BST-controlled ablation. This animal study aims to evaluate the accuracy of a newly developed BST-monitoring system and validate the optimal BST for ablation. METHODS AND RESULTS: In Protocol 1, thermocapsules were attached to the superior vena cava (SVC) epicardium. The accuracy of BST monitoring was examined during SVC isolation. In Protocol 2, the efficacy and safety of different BST-controlled ablations were examined. In the acute model, electrophysiological and pathological findings were assessed after energy applications with BST at 51, 54, 57, and 60°C. In the chronic model, the lesion durability and pathological findings were assessed 8 weeks after BST-controlled ablation (57 and 60°C). A significant positive correlation was found between the epicardial temperature and the BST-monitoring value (r = 0.98). In the acute model, all target veins were electrically isolated with BST-controlled ablation at ≥57°C (18/18, 100%). In the chronic model, durable lesions were observed in all veins at 60°C, while 44% of the veins showed reconnection at 57°C. In both pathological analyses, significantly greater lesions were observed at 60°C than at 57°C. There were no significant differences in adverse events between the two groups. CONCLUSION: Balloon surface temperature-controlled ablation at 60°C using the second-generation RHB may be optimal for creating durable lesions without compromising safety.

Respiratory control minimizes diaphragmatic contraction and dry cough during pulsed-field ablation of atrial fibrillation.

AIMS: Pulsed-field ablation (PFA) is a promising new ablation modality to treat atrial fibrillation. However, PFA can cause varying degrees of diaphragmatic contraction and dry cough, especially under conscious sedation. This prospective study presents a method to minimize the impact of PFA on diaphragmatic contraction and dry cough during the procedure. METHODS AND RESULTS: Twenty-eight patients underwent PFA for pulmonary vein (PV) and superior vena cava isolation under conscious sedation. Each patient received two groups of ablations in each vein: the control group allowed PFA application during any phase of respiratory cycle, while the test group used respiratory control, delivering PFA energy only at the end of expiration. A rating score system was developed to assess diaphragmatic contraction and dry cough. A total of 1401 control ablations and 4317 test ablations were performed. The test group had significantly lower scores for diaphragmatic contraction (P < 0.01) and dry cough (P < 0.001) in all PVs compared to the control group. The average relative reductions in scores for all PVs were 33-47% for diaphragmatic contraction and 67-83% for dry cough. The percentage of ablations with scores ≧2 for diaphragmatic contraction decreased significantly from 18.5-28.0% in the control group to 0.4-2.6% in the test group (P < 0.001). For dry cough, the percentage decreased from 11.9-43.7% in the control group to 0.7-2.1% in the test group. CONCLUSION: Pulsed-field ablation application at the end of expiration can reduce the severity of diaphragmatic contraction and eliminate moderate and severe dry cough during PV isolation performed under conscious sedation.

Preclinical assessment of the feasibility, safety and lesion durability of a novel 'single-shot' pulsed field ablation catheter for pulmonary vein isolation.

AIMS: Single-shot pulmonary vein isolation can improve procedural efficiency. To assess the capability of a novel, expandable lattice-shaped catheter to rapidly isolate thoracic veins using pulsed field ablation (PFA) in healthy swine. METHODS AND RESULTS: The study catheter (SpherePVI; Affera Inc) was used to isolate thoracic veins in two cohorts of swine survived for 1 and 5 weeks. In Experiment 1, an initial dose (PULSE2) was used to isolate the superior vena cava (SVC) and the right superior pulmonary vein (RSPV) in six swine and the SVC only in two swine. In Experiment 2, a final dose (PULSE3) was used for SVC, RSPV, and left superior pulmonary vein (LSPV) in five swine. Baseline and follow-up maps, ostial diameters, and phrenic nerve were assessed. Pulsed field ablation was delivered atop the oesophagus in three swine. All tissues were submitted for pathology. In Experiment 1, all 14/14 veins were isolated acutely with durable isolation demonstrated in 6/6 RSPVs and 6/8 SVC. Both reconnections occurred when only one application/vein was used. Fifty-two and 32 sections from the RSPVs and SVC revealed transmural lesions in 100% with a mean depth of 4.0 ± 2.0 mm. In Experiment 2, 15/15 veins were isolated acutely with 14/15 veins (5/5 SVC, 5/5 RSPV, and 4/5 LSPV) durably isolated. Right superior pulmonary vein (31) and SVC (34) sections had 100% transmural, circumferential ablation with minimal inflammation. Viable vessels and nerves were noted without evidence of venous stenosis, phrenic palsy, or oesophageal injury. CONCLUSION: This novel expandable lattice PFA catheter can achieve durable isolation with transmurality and safety.

Visualization and mapping of the right phrenic nerve by intracardiac echocardiography during atrial fibrillation ablation.

OBJECTIVE: This study aimed to evaluate the feasibility of real-time visualization and mapping of the right phrenic nerve (RPN) by using intracardiac echocardiography (ICE) during atrial fibrillation (AF) ablation. BACKGROUND: RPN injury is a complication associated with the ablation of AF. Multiple approaches are currently being used to prevent and detect RPN injuries. However, none of these approaches can directly visualize the RPN in real-time during the ablation procedure. METHODS AND RESULTS: The RPN was detected using ICE. The RPN and its adjacent structures were analysed. The relationship between the RPN's distance from the superior vena cava (SVC) and its pacing capture threshold was quantified. The safety of SVC isolation guided by the ICE-visualized RPN was evaluated. Thirty-eight people were enrolled in this study. The RPN was visualized by ICE in 92% of patients. It ran through the space between the SVC and the mediastinal pleura and had a 'straw'-like appearance upon ICE imaging. The course of the RPN was close to the SVC (minimum 1.0 ± 0.4 mm) and the right superior pulmonary vein (minimum 14.1 ± 7.3 mm). There was a positive linear correlation between the RPN's capture threshold and its distance from the SVC (Spearman's correlation coefficient = 0.728, < 0.001). SVC isolation was guided by the RPN; none of the patients developed an RPN injury. CONCLUSIONS: RPN can be visualized by ICE in most patients, thus providing a novel approach for the real-time detection of RPN during AF ablation.

Superior vena cava tear during transvenous lead extraction: Medical management in hemodynamically stable patients.

INTRODUCTION: Superior vena cava (SVC) tear is the most lethal complication during transvenous lead extraction (TLE) with a mortality rate as high as 50%. Treatment involves aggressive attempts to maintain cardiac output and immediate sternotomy to localize and repair the vascular tear. Occlusion balloons have been developed to provisionally occlude the lacerated SVC and to provide hemodynamic stability allowing time for surgery. In case of mediastinal hematoma without hemodynamic instability, the strategy remains unclear. METHODS AND RESULTS: We describe two cases of SVC tear during TLE. The first case was a 60-year-old man who presented with a right ventricular single-chamber defibrillator lead fracture and innominate vein stenosis. The RV lead was removed using a laser sheath causing a mediastinal hematoma with no active bleeding during surgical exploration few hours later. The second case was a 28-year-old man that presented with a right atrial (RA) lead fracture and RV lead insulation failure in a dual-chamber defibrillator (ICD). CONCLUSION: Both the RA and RV leads were removed with mechanical sheaths, and a mediastinal hematoma was medically managed.

Tall P-waves in inferior leads: A case of coexisting ectopic rhythm and atrial fibrillation arising from the superior vena cava.

Suppression of atrial fibrillation (AF) arising within the superior vena cava (SVC) requires SVC electric isolation (SVCI) without sinus node (SN) injury. If an ectopic rhythm and AF trigger coexist within the SVC, the intra-SVC ectopic rhythm complicates the pre-SVCI search for the SN. This coexistence is without precedent; however, it is important to carefully locate the SN to prevent injury during SVCI. This case shows a paroxysmal AF with both phenomena coexisting in the SVC. Moreover, outpatient electrocardiographic assessment for tall P-waves in inferior leads before catheter ablation could predict these phenomena and enable safer SVCI.