Irrigated Catheter Research Articles

Blood Pressure Control and Clinical Outcomes After Renal Denervation Through Irrigated Catheter Radiofrequency Ablation in Patients with Resistant Hypertension: A Case Series with Up to 10 Years of Follow-Up.

The long-term efficacy of renal denervation (RDN) has not been extensively documented. To describe the long-term follow-up of patients after RDN. We evaluated patients with resistant hypertension (RH) who underwent RDN with irrigated catheter from 2012 to 2014 at a single centre. Office blood pressure (BP) and 24-hour ambulatory BP were assessed. Clinical event (stroke, myocardial infarction, need for dialysis, or death from any cause), left ventricular mass index (LVMI), estimated glomerular filtration rate (eGFR), and urine albumin-to-creatinine ratio (uACR) were evaluated. The analysis included 20 individuals (age 51 ± 10 years, 75% female, ambulatory systolic BP [SBP] 168 ± 22 mmHg, ambulatory diastolic BP [DBP] 101 ± 19 mmHg, taking 7 [IQR: 6-8] antihypertensive medications). The median follow-up period was 8.5 (IQR: 5.6-9.4) years. Mean (± SD) changes from baseline were: -47 ± 41 mmHg for office SBP, -25 ± 20 mmHg for office DBP, -29 ± 26 mmHg for ambulatory SBP, and -15 ± 16 mmHg for ambulatory DBP. The number of antihypertensive drugs markedly decreased one month after RDN and a gradual upward trend was observed over time. A clinical event occurred in 9 (45%) participants. LVMI decreased from 152 ± 37 to 120 ± 31g/m2 (p = 0.015), the eGFR declined from 88.9 ± 15.6 to 73.1 ± 24.2 mL/min/1.73 m2 (p = 0.034), and the uACR did not significantly change from baseline to follow-up. In this observational study of patients with uncontrolled RH, RDN with an irrigated catheter was associated with a sustained BP reduction for up to a decade. However, a potential waning efficacy was suggested by the increasing use of antihypertensive medications over time.

Submyocardial Pacing Threshold Distribution During Cold Saline Application; Exploring Reversible Arrhythmia Inhibition.

Cold saline application through an irrigation catheter may induce reversible inhibition of submyocardial excitation, which may be used to identify in advance an ideal site for radiofrequency (RF) energy delivery around delicate areas. An open irrigation catheter was positioned vertically or parallel with 10-g contact on coronary perfusing porcine hearts and the contacted myocardium was cooled by cold saline at 4°C (20mL/min). A temperature electrode was inserted 2mm below the myocardial surface (intra-myocardial temperature at approximately 2 mm below the surface [Temp-BS]). Pacing threshold inside the ventricular wall was measured using aneight-pole electrode plunge needle inserted 5-8mm close to the ablation catheter, and percent increase of the pacing threshold by the cold saline application (%increase-PT) was calculated. During cooling, pacing at 10V from the myocardial surface interrupted constant capture in 7/10 experiments in vertical and in 9/10 experiments in parallel ablation catheter contact. Minimum Temp-BS was not different in both catheter contact positions (25.9±4.0°C in vertical vs. 25.4±2.6°C in parallel). Large % increase-PT on the surface myocardium decreased as the myocardial depth became deeper, and > 150% increase was at a depth approximately 2-3mm from the surface and > 120% increase around 6-7mm from the surface. After cessation of cold saline application, the increased %increase-PT recovered to the pre-cooling values. Cold saline application through an irrigation catheter reversibly inhibited submyocardial excitation. This simple method may have the potential to pre-determine the ideal ablation site in sensitive areas of the heart, although further studies and technological adjustments are required before clinical use.

Abstract 4135869: Local Ethanol Infusion after Pulsed Field Ablation Enhances Acute Efficacy of In Vivo Ventricular Electroporation

Background: Pulsed field ablation (PFA) has emerged as an innovative technology for treating cardiac arrhythmias. PFA increases cell permeability, which can lead to apoptosis. Greater PFA energy may be necessary to ablate ventricular myocardium for ventricular tachycardia circuits, but this carries risks of side effects such as gaseous formation (microbubbles) and hemolysis. Ethanol (EtOH) infusion has been used to ablate pathologic myocardial tissues in hypertrophic cardiomyopathy and for refractory arrhythmias. Hypothesis: We hypothesize that PFA in the ventricle can increase EtOH uptake through PFA-generated pores, thereby enhancing ablation efficacy, even at low powers, by utilizing the cell permeability effects of PFA. Aim: The aim of this study is to investigate the effect of local EtOH infusion after PFA on lesion size in porcine ventricles. Methods: The ventricles of five porcine subjects were ablated in vivo with a PFA low power setting (750 V, at 20 μs for 50 pulses separated by 200 ms) using a focal bipolar irrigated ablation catheter and BTX 830 electroporation generator (Harvard Apparatus). After PFA was performed, 2 ml of 90 % EtOH vs. saline (control) was infused through the catheter tip to the site of ablation. We compared the electrograms voltage amplitude reduction before and after PFA, and the ablation lesion characteristics. Results: A total of 10 lesions in the control group and 9 lesions in the EtOH group were analyzed. For the controls, the voltage after PFA was not reduced. In contrast, for the EtOH group, the voltage after PFA was significantly reduced ( Figure 1A ). On gross pathology, there were significant differences in ablation lesion depths and volumes between the 2 lesion sets ( Figure 1A-B ). Conclusion: Local EtOH infusion after ventricular PFA enhanced acute efficacy of electroporation. Concurrent PFA with local EtOH infusion has the potential to improve efficacy without requiring higher energy parameters, thereby reducing PFA risks. Future studies on chronic efficacy are warranted.

Abstract 4135872: Effects of In-vivo Contact Force on Pulsed Field Ablation Lesion Size in Porcine Ventricles

Background: Pulsed field ablation (PFA) is an innovative modality for treating arrhythmias that is mostly non-thermal and renders myocardial tissue non-viable by creating pores in cardiac cell membranes. The impact of contact force (CF) on PFA efficacy is not well characterized. Hypothesis: We hypothesize that, while contact is necessary for PFA, increasing CF will not have a significant effect on in vivo ablation lesion size. Aim: We seek to investigate the effects of CF on acute PFA lesions in a beating porcine heart model. Methods: The ventricles of 7 porcine animals were ablated in vivo with PFA (500V, at 20μs for 50 pulses separated by 200ms) using a focal bipolar irrigated ablation catheter and BTX 830 electroporation generator (Harvard Apparatus). CF was measured before and after each PFA application using CARTO 3. Lesions were divided into standard CF (5-15g), high CF (16-30g), and very high CF (>31g). Results: A total of 46 lesions were analyzed. Gross pathology showed no significant difference in maximum width, lesion depth, and lesion volume between the three groups ( Figure 1A-B ). Linear regression showed a decrease of 0.003 mm in depth (depth = -0.003 × CF + 1.8, R = 0.05), an increase of 0.01 mm in width (width = 0.01 × CF + 5.7, R = 0.09), and a decrease of 0.05 mm 3 in volume (volume = -0.05 × CF + 26.8, R = 0.03) for each additional gram of CF ( Figure 1C ). Conclusion: While contact is necessary, increasing CF did not have a significant effect on in-vivo PFA lesion dimensions in a beating porcine heart model.

Abstract 4114716: Concurrent Ethanol Infusion with Pulsed Field Ablation Augments Electroporation of Porcine Atria

Background: Pulsed field ablation (PFA) is a promising modality for treatment of cardiac arrhythmias. PFA increases cell permeability, thereby promoting cell apoptosis. Although greater PFA energy may produce larger lesions, it also carries risks of side effects such as arcing, hemolysis, and microbubbles. Chemical ablation using ethanol (EtOH), such as with injection of the Vein of Marshall, has been used to treat atrial myocardium for refractory atrial arrhythmias. Hypothesis: We hypothesize that PFA in the atria can increase EtOH uptake through PFA-generated pores, thereby augmenting ablation efficacy by utilizing the cell permeability effects of PFA. Aim: The aim of this study is to investigate the effects of local EtOH infusion after PFA on lesion size in porcine atria. Methods: The atria of five porcine subjects were ablated in vivo with low PFA power settings (250V, at 20μs for 50 pulses separated by 200 ms) using a focal bipolar irrigated ablation catheter and BTX 830 electroporation generator (Harvard Apparatus). After PFA, 2 ml of 90 % EtOH vs. saline (control) was infused through the catheter tip to the site of ablation. We compared electrogram voltage amplitude reduction and ablation lesion parameters before and after PFA. Results: A total of 14 control lesions and 14 EtOH lesions were analyzed. There was significant difference in voltage reduction between two groups ( Figure 1A-B ). On gross pathology, there were significant differences in ablation lesion maximum surface diameter, lesion depth, and volume between the 2 lesion sets ( Figure 1C ). Conclusion: Concurrent EtOH infusion after PFA enhanced acute efficacy of electroporation in porcine atria. Adjuvant therapy has the potential to improve efficacy without requiring higher energy parameters, thereby reducing PFA risks. Further studies to assess chronic efficacy are warranted.

Abstract 4137447: Length of WACA line Affects 1 st Pass Success rates in PVI

Background: Standard ablation for atrial fibrillation consists of wide antral pulmonary vein isolation, efficacy for which depends on a contiguous series of ablation lesions. The larger a circumference ablated around the pulmonary veins, the more challenging it may be to ensure durable isolation, due to technical and anatomic factors, which may in turn contribute to higher rates of atrial fibrillation (AF) recurrence. The relationship between WACA size and success rates may inform procedural methods and optimize outcomes. Objective: To examine the relationship between length of WACA lines and ablation success in patients that have undergone a PVI ablation. Methods: We performed a single-center, retrospective analysis of a consecutive series of 258 patients who underwent 1 st pulmonary vein isolation (PVI) for the treatment of atrial fibrillation, between 1/1/2022 and 6/30/2023. Radiofrequency ablation (RFA) was performed using 50 W with a contact-force sensing irrigated catheter. Information on acute 1 st pass success for left and right vein was recorded. The length of each WACA line was traced out manually, following the center of the ablated lesions. Follow up information consisted of AF recurrence at three, six, and twelve months. Student t-test was used for comparison of means and Chi-square test was used for categorical variables. Results: All veins were successfully isolated in all patients. WACA 1 st pass success rates were 87% in the left veins, and 83% in the right veins. Right WACA lines were generally longer. In patients with Left WACA 1 st pass success, the average length of the WACA line was 94.8cm, compared to 100.1cm in the group without 1 st pass success (p=0.025). In patients with right WACA 1 st pass success, the average length of the WACA line was 105.8cm, compared to 110.6cm in the group without 1 st pass success (p=0.07). When evaluating post PVI patients for recurrence of AF at 1year, there was a non-statistically significant association of AF recurrence with longer combined L+R WACA lines during index PVI (205.5cm vs 197.0cm, p=0.065). Conclusion: Longer WACA lines during index PVI are associated with failure of 1 st pass isolation. Further study is needed to address the mechanism by which longer WACA lines affect ablation efficacy, whether due to technical factors reflecting something intrinsic to underlying substrate.

Whole Lung Lavage in Autoimmune Pulmonary Alveolar Proteinosis: Unique Challenges in a Resource-Limited Setting.

Autoimmune pulmonary alveolar proteinosis (PAP) is characterized by antibodies to granulocyte-macrophage colony-stimulating factor (GM-CSF), alveolar macrophage dysfunction, and surfactant accumulation. Whole lung lavage (WLL) is the treatment of choice in patients with PAP and severe hypoxemia. In resource-limited settings, WLL can be performed in the intubated, anesthetized patient who is being one lung ventilated using a Y-type bladder irrigation catheter for saline instillation and drainage.

Suppurative Flexor Tenosynovitis: A Case Report

Background: Suppurative flexor tenosynovitis is an infection of the flexor tendon sheath. This case report presents the clinical course and management of a patient diagnosed with suppurative flexor tenosynovitis. The diagnosis is based on history taking, physical examination, and supporting examination findings. Case Report: A 42-year-old man presented with chief complaints of pain, swelling, and immobility of the index finger of his right hand after being pierced by a fish spine 3 days prior. Physical examination revealed the second digit in a slightly flexed and swollen position, with pain elicited on palpation and passive extension, limiting the patient's range of motion. The patient was diagnosed with suppurative flexor tenosynovitis and treated with antibiotics, debridement, and drainage. Postoperative results were good, with no signs of complications such as spread of infection, tendon necrosis, osteomyelitis, or indications for amputation.Discussion: The treatment for suppurative flexor tenosynovitis involves a combination of antibiotics and surgery. Surgical interventions typically include open drainage and debridement or closed catheter irrigation. Additionally, postoperative rehabilitation is a crucial aspect that requires careful consideration, as it has been shown to accelerate the healing process.Conclusion: Suppurative flexor tenosynovitis is a rare but serious condition that demands early detection and a multidisciplinary approach. Timely surgical debridement and targeted antibiotics, guided by the identification of the causative organism, are essential for positive patient outcomes.

Impact of irrigation flow rates on lesion size and safety of ablation catheters: an ex vivo porcine heart study.

Radiofrequency (RF) catheter ablation is a well-established therapeutic approach for treating arrhythmias, where lesion size and safety are critical for efficacy. This study explored the impact of varying irrigation flow rates on lesion characteristics using the TactiFlex™ SE Ablation Catheter (TF) in an ex vivo porcine heart model, focusing on the size and safety outcomes associated with low versus standard flow rates. Myocardial slabs from porcine hearts were subjected to ablation using two types of irrigated catheters. Lesion formation was compared between low (8mL/min for TF) and standard irrigation flow rates (13mL/min for TF) across different power settings (30, 40, and 50 W). Outcome measures included lesion dimensions, incidence of steam pops, and impedance drops. A total of 210 lesions were generated under various settings. At low flow rates, the TF catheter safely formed larger lesions compared to the standard flow rates without a significant increase in steam pops or impedance drops. Lesions at low flow rates were comparable in size to those formed using other catheters under the standard settings. Conversely, the standard flow settings for TF produced smaller lesions but exhibited higher safety profiles, as evidenced by fewer steam pops and impedance drops. Lower irrigation flow rates using a TF catheter can achieve larger lesions without compromising safety, offering an optimization strategy for RF ablation procedures that balances efficacy and safety. These findings may guide clinicians in tailoring ablation strategies according to individual patient needs.

The Comparison between the conservative approach and pectoralis major flap transposition in the treatment of mediastinitis following median sternotomy

Background: Mediastinitis is a significant complication of open heart surgery and other thoracic operations. Deep sternal wound complications notably increase morbidity and mortality. The optimal treatment for deep sternal wounds following sternotomy remains a topic of discussion. Options such as repeated irrigation and debridement of the wound, closed chest catheter irrigation, and recent plastic surgery approaches like pectoralis major flap transposition all have their proponents Methods: Given the high prevalence of Deep Sternal Wound Infection (DSWI), we conducted this retrospective descriptive study. We used existing information to compare the conservative method of repeated irrigation and debridement with pectoralis major flap transposition. We presented the results using descriptive and analytic methods. We evaluated a total of 125 patient health records with deep sternal wound infection over a ten-year period (2003-2013). Results: The results of this study showed that 83.2% of patients who developed DSWI after surgery suffered from underlying diseases such as diabetes, renal failure, etc. However, no relationship was found between the presence of an underlying disease and recovery. Furthermore, no significant relationship was observed between diabetes and recovery. Among the 125 assessed files, 50 patients received a pectoralis flap, among which 48 patients recovered with sternal stabilization and only 2 patients recovered without stabilization. Conversely, among cases without pectoralis flapping, records were available for only 67 patients, of whom only 35 patients recovered with sternal stabilization while 32 patients recovered without sternal stabilization. Recovery was significantly enhanced in the group receiving flapping. Conclusions: The only factor that improved the outcome in our assessment was the use of pectoralis flapping. This is consistent with the results of studies published in recent years that used plastic surgery methods, i.e., pectorals muscle or omentum flapping, which are associated with a high success rate and reduced length of inpatient stay.

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.

Urinary Catheter-Related Meatal Pressure Injury Risk Factors in Male Critical Care Patients: A Prospective Repeated-Measures Study.

Urinary catheter-related meatal pressure injury (UCR-MPI) is a preventable and serious complication of indwelling urinary catheter use. This prospective study aimed to determine the prevalence and risk factors of UCR-MPI in male critical care patients. A total of 138 male patients 18 years and older using an indwelling urinary catheter were included in the study. Participants' perineal areas were assessed daily for the development of MPI. The UCR-MPI prevalence was 26.1% (n = 36/138). Most patients (61.1%) had a grade I UCR-MPI with intact skin and mucosa and nonblanchable erythema. Urinary catheter irrigation (P = .001), lower Braden Scale scores (P = .040), lower Glasgow Coma Scale score (P = .002), higher Itaki Fall Risk Scale score (P = .040), higher dependency level (P = .027), hypoalbuminemia (P = .002), and perineal edema (P = .001) were risk factors for UCR-MPI. The prevalence of UCR-MPI was high in this sample. Providers should take preventive measures to prevent UCR-MPI in patients with a penis including early and frequent risk assessment.

Comparative study of lesions obtained with radiofrequency between irrigated ablation catheter with flexible tip and non-irrigated catheter in ex vivo porcine heart slices

Abstract Background Lesion formation through radiofrequency (RF) is related to various parameters, including power, contact force, duration of energy delivery and temperature. Notably, the characteristics of the lesions differ when comparing irrigated to non-irrigated catheters. Non-irrigated catheter lesions present a larger surface area and shallower depth, while irrigated catheters induce deeper lesions with higher volumes. Particularly, flexible-tip open-irrigated catheter exhibit unique irrigation characteristics and the resulting lesions may show a reduced surface area but extend deeper into the tissue. Main drawbacks of using non-irrigated catheter are the risk of clot formation and of steam pops, both possibly avoidable with an irrigated catheter. Purpose The aim of the study was to demonstrate that flexible-tip open-irrigated catheter generate lesions with a smaller surface area and deeper extension when compared to non-irrigated catheter. Methods An ex vivo model consisting of porcine heart slices in a warmed saline chamber was used. A flexible-tip open-irrigated ablation catheter and a non-irrigated catheter were positioned with a stable tissue contact weight ranging from 10 to 20 g of force in perpendicular position. RF was delivered at powers of 20, 30 and 40 Watt for 60s. Lesion dimensions were analyzed. The occurrence of steam pop was registered. Results The ablations were conducted using flexible-tip open-irrigated (n=55) and non-irrigated (n=39) catheters in a power-control mode. Superficial length and width of lesions were greater with the non-irrigated catheter than with the irrigated catheter, irrespective of the power delivered (superficial length: p=0,0001 at 20W, p=0,002 at 30 W and p=0,0001 at 40 W; superficial width: p=0,001 at 20 W, p=0,019 at 30 W and p=0,003 at 40 W). When computing superficial areas, lesions performed with the non-irrigated catheter were significantly wider, regardless of the power delivered (p=0,001 at 20 W, p=0,005 at 30 W and p=0,001 at 40 W). The irrigated catheter determined significantly greater values of lesion maximum depth at high power delivery (40 W, p=0.007). No steam pop was observed using the irrigated ablation catheter, while 12 steam pops occurred with the non-irrigated catheter. Conclusions This study highlights that RF ablation using flexible-tip open-irrigated catheter has the potential to generate smaller lesion areas when compared to a non-irrigated tip. Furthermore, it may contribute to decrease steam pops, even with escalating power output. This irrigated catheter might be a preferable choice when precision is crucial, particularly in determining superficial area of lesions. Specifically, it might be advantageous for procedure as atrioventricular nodal reentry tachycardia (AVNRT) ablation, minimizing the risk of iatrogenic conduction disturbance related to RF delivery in the region of the compact AV node, located superficially at a millimeter distance from the ablation site.Experiment setting, lesion measurementsLesion superficial area

Safety and efficacy of a temperature-controlled ablation system for ventricular tachycardia: first results from the TRAC-VT study

Abstract Background Catheter ablation using radiofrequency (RF) energy, is a well-recognized treatment option for patients with ventricular arrhythmias. However, procedural complications may be high, and efficacy is often suboptimal with high recurrence rates. Purpose The TRAC-VT study evaluated safety and efficacy of the DiamondTemp Ablation (DTA) System for the treatment of patients with ventricular arrhythmias by catheter ablation. Methods A temperature-controlled, irrigated RF catheter (with six thermocouples and an internal network of diamond coatings) was utilized to treat subjects with either sustained monomorphic ventricular tachycardia (VT) and structural heart disease or with frequent monomorphic symptomatic ventricular premature beats (VPBs) and normal hearts. Patients were enrolled at five hospital centers in five European countries and were followed for 6 months. Ablation was performed in temperature-control mode with an irrigation flow of 8 mL/min for all power deliveries. The target temperature was set to 55 or 60 °C with a power output limited to 50 Watts. RF energy was applied for a maximum of 45 seconds per target site, depending on impedance drop and electrogram abatement. Results The study enrolled 49 subjects (age 67±12 years, 80% male) in total (38 with sustained monomorphic VT and structural heart disease and 11 with symptomatic VPBs). In all cases, mapping and navigation was used with EnSite systems (Abbott). The average ablation time (defined as time from the insertion of the DTA catheter until removal from body) was 87 ± 44 minutes. During this time, RF energy was applied for an average of 28.2 ± 10.2 seconds with a power of 44.0 ± 7.0 W and a temperature of 50.9 ± 3.9 °C during 35.0 ± 23.2 applications. Acute procedural success was 100% (93%-100%), and it was defined as the elimination of VPBs or non-inducibility for sustained VT (using solely the DTA catheter). The primary safety procedure-related endpoint was an evaluation of cardiovascular-related death, stroke / TIA, cardiac tamponade/perforation, bleeding complication, myocardial infarction, thromboembolism, and pulmonary edema. In total review of the primary safety endpoint, one subject had a confirmation of a stroke / TIA event. Regarding longer term procedural efficacy, the 6-month follow-up was completed in 92% of subjects. For the whole study population chronic success from recurrence of ventricular arrhythmia (faster than 100 beats/min after 6 months) was 73.4% (58.6%-83.6%) for non-sustained ventricular arrhythmias (≥3 beats) and 87.7% (74.7%-94.3%) for sustained ventricular arrhythmias (≥30 sec). Conclusions VT/VPBs ablation using a temperature-controlled irrigated RF catheter was safe and effective with low VT recurrence at 6 months of follow-up.

Cardioneuroablation guided by extracardiac vagal stimulation for cardioinhibitory vasovagal syncope

Abstract Introduction Vasovagal Syncope (VVS) is often linked to abnormal autonomic reflexes, with hypervagotonia identified as a key mechanism, especially in cases with pronounced cardioinhibition. Cardioneuroablation (CNA), which involves radiofrequency ablation of cardiac vagal ganglia, targets parasympathetic hyperactivity, offering a promising treatment for recurrent VVS. This study evaluates the effectiveness and safety of anatomically guided CNA, which may provide an alternative treatment option to pacemaker implantation for younger patients with severe cardioinhibitory VVS. Methods Consecutive patients between January 2019 and October 2023 who underwent CNA at two cardiology centers were enrolled. All patients had a history of recurrent syncope, predominantly cardioinhibitory and unresponsive to conventional treatments. Patients showed no signs of conduction system disease, evidenced by normal rate responses in treadmill stress tests and 24-hour Holter monitoring. Electroanatomic mapping of the left atrium and pulmonary veins was performed. Extracardiac vagal stimulation (ECVS) through the right internal jugular vein, with or without atrial pacing, was utilized to assess baseline responses of the sinus and atrioventricular (AV) nodes. The ablation strategy was tailored based on rhythm disturbances triggered by ECVS, using sequential and anatomically guided ablation of ganglionated parasympathetic plexuses. Radiofrequency ablation, conducted with an irrigated catheter, was guided by the ablation index. Acute success was defined as the absence or significant reduction of cardiac parasympathetic response to ECVS, indicated by the elimination of asystole, severe bradycardia, or AV block. The primary endpoint was syncope recurrence during follow-up. Results The study included 25 patients (16 males; mean age 36 ± 12 years). All had documented cardioinhibition, identified through ECG monitoring (N=12), implantable loop recorders (N=5), or head-up tilt tests (N=8). The average number of syncopal episodes per patient in the year preceding ablation was 2.7, ranging from 1 to 10. Ablation was acutely successful in all cases. Post-ablation, there were no immediate complications related to the procedure, except for one convulsion deemed unrelated. Over a mean follow-up of 17 ± 14 months, 23 patients remained syncope-free. Two patients experienced syncope recurrence; despite undergoing a repeat ablation, they eventually required pacemaker implantation. Conclusion The results of this study suggest that CNA guided by ECVS, may offer a promising treatment for patients with refractory cardioinhibitory VVS. While the procedure showed a high rate of acute success and a notable reduction in syncope recurrence, further research is warranted to fully establish its role as an alternative to pacemaker implantation.

Simplification of resetting response in slow/fast atrioventricular nodal reentrant tachycardia: the 3 catheters approach

Abstract Background The resetting response is a maneuver that helps identify the anterograde limb of slow/fast atrioventricular nodal reentrant tachycardia (AVNRT). The actual described maneuver involved a 5 catheters approach, and the related complications are poorly described.(1) Purpose We describe a simplified approach with 3 catheters and the related complications of the maneuver. Methods A quadripolar catheter was placed in the His bundle region; a decapolar catheter in the coronary sinus (CS) and a 4 mm tip non irrigated or irrigated catheter was used for pacing and ablation. An 8.5 French Sl0 sheath was used to ensure contact and stability. In confirmed slow/fast AVNRT using the fast pathway as the retrograde limb (earliest retrograde atrial activity located in the parahisian region), a single decremental atrial extrastimulus was delivered at the lower part of the triangle of Koch and 2-3 cm inside the CS on the roof. Pacing maneuver was started near the end of the QRS complex and decremented by 10 ms per interval. The higher atrial signal with the best A/V ratio on the CS catheter was used as sense reference for resetting response. The end point of ablation was non inducibility. Results Ten patients were included in a 4-month period, comprising 2 redo procedures. The maneuver was not performed in 4 patients (40%) due to non-sustained tachycardia. Atrial fibrillation was induced in 2 patients (20%) during the maneuver systematically due to an atrial extrastimulus preceding the H potential (negative HA interval). In the 4 remaining patients with successful resetting response, the HA interval in successful ablation spot varies between 31 to 82 ms. The involved anterograde limb was the right extension in 3 (75%) and the left extension in 1 (25%). Conclusion Resetting response can be performed with a 3 catheters approach, the main limitation is non sustained tachycardia, and atrial fibrillation induced by short coupled extrastimulus.Resseting response in LIE and RIE

Radiofrequency lesion in atrial wall: how variable is it? 9 Tesla MRI analysis of RF lesion volume in a swine model

Abstract Background Little is known about radiofrequency (RF) lesion volume (rLV). Most of animal or ex-vivo studies quantify the size of RF lesions size using width and/or depth, while electrophysiologists use manufacturers’ indirect indices (such as Ablation Index or Lesion Size Index). Purpose We aimed to evaluate rLV by high resolution 9-Tesla magnetic resonance imaging (MRI), in ex-vivo swine model. We studied the variability of rLV and extra-cardiac effects in two groups of swine, one treated with low energy (LE)-long application RF (20W-50 sec) and another treated with high energy (HE)-short application RF (50 W-20 sec). Methods This was a prospective observational study on 18 piglets, that were anesthetized, mechanically ventilated, and divided into LE (n = 9) and HE (n = 9) groups (Figure 1). An irrigated contact force catheter was used to perform RF applications in 4 largely separated spots: 2 on right atrium and 2 on left atrium wall. RF parameters were monitored during RF. Each animal was sacrificed after 5-7 days, and RF lesion samples were excised and acquired by 9 MRI. Results 70 RF applications were performed (36 in LE group and 34 in HE group). MRI was performed on 26 samples of LE group and 28 of HE group (Figure 2). The median RF lesion volume was 89.3 mm3 (IQR 47.9-175.9). Regarding lesion volume, the HE groups showed 35% higher volume than LE group (mean lesion volume 86.2 mm3 vs 116.3 mm3, p = 0.119). HE group also showed more complications (0 vs 7, p=0.02) and more extracardiac lesion (14 vs 18, p=0.613). Conclusions There was a wide and unpredictable variability of RF lesion on atrial wall, even under controlled experimental conditions, which could explain arrhythmias recurrences. The variability seems greatest, although not statistically significant, during HE applications. The dose/effect relationship needs to be carefully studied for treatments of cardiac arrhythmias for both RF and other forms of energy available today.Study flow-chartComparison between groups

High-density mapping-guided ventricular tachycardia ablation in patients with ischemic cardiomyopathy: outcomes from a tertiary center cohort in Switzerland

Abstract Background Substrate-based ablation has emerged as a successful technique for VT ablation, especially in patients with ischemic cardiomyopathy with markedly reduced left ventricular function. High-density mapping catheters provide high-resolution electroanatomical maps and better discrimination of abnormal substrates and local activation in the heart chambers, making them a valuable and safe resource in the electrophysiology laboratory. Purpose The purpose of this study was to investigate differences in procedural characteristics and clinical outcomes of VT ablation with ischemic cardiomyopathy. VT ablations were guided by two mapping strategies: high-density mapping using a high-density mapping catheter and conventional mapping using an ablation catheter. Methods Patients with ischemic cardiomyopathy receiving VT ablation at our center between January 2018 and June 2023 were retrospectively included. Procedural characteristics and clinical outcomes were compared between patients receiving high-density mapping with a multielectrode-mapping catheter vs conventional mapping with a single-tip irrigated ablation catheter. Results Eighty-four patients with ischemic cardiomyopathy who underwent VT ablation were consecutively included (mean age 67 ± 12 years, mean LVEF 32 ± 11 %, 79 (94%) males). Fifty-seven (68 %) procedures were performed using high-density mapping, and 27 (32 %) conventional mapping. In the high-density mapping and conventional mapping group, the total procedure time was 256 ± 77 min vs. 232 ± 61 min (P &amp;lt; 0.05) and the total fluoroscopic dose was 1643 ± 204 μGy.m2 vs. 948 ± 105 μGy.m2 (P &amp;lt; 0.05), respectively,. However, there was no difference between the two groups in terms of acute success (84% vs 80%, P &amp;gt; 0.05) or major complications (5% vs 4%, P &amp;gt; 0.05). The mean duration of follow-up was 2.6 years (4 - 51 months). The 1-year mortality rates were 4% vs 7% in the high-density mapping and conventional mapping groups, respectively (P &amp;lt; 0.05). The 3-month and 1-year single-procedural sustained VT/VF-free rates were 77% vs 59% and 74% vs 63%, respectively (P &amp;lt; 0.05). The 1-year incidence of sustained VT/VF recurrence was 7.0 per 100 person-years in high-density mapping group, compared with 7.4 per 100 person-years in the conventional group. Conclusions VT ablation in patients with ischemic cardiomyopathy using high-density mapping appears to be superior to conventional mapping in terms of reducing postprocedural VT/VF recurrence and a subsequent reduction of overall mortality.Figure 1Figure 2

Modification of deceleration zones and late potentials after ventricular tachycardias substrate ablation

Abstract Introduction Characterization of ventricular substrate is crucial during ventricular tachycardias (VT) ablation. Isochronal Late Activation Mapping (ILAM) is a recently introduced visualization tool that permit to identify areas of slow conduction (deceleration zones, DZs), these seems to well correlate with VT isthmuses. However, there are limited data about changes in this substrate after catheter ablations. Purpose To evaluate changes that occur to DZs and late potentials (LPs) after repeated ablative lesion sets. Methods High density voltage map and ILAM of the left ventricles (LV) during paced rhythm were performed in all cases. LV activation map was divided into 8 isochrones and DZ was defined as the presence of 3 isochrones within 1 cm-radius. LPs were defined as EGMs with late and fragmented components after the QRS. PES was performed at the beginning and at the end of the procedure. Each RF lesion set were applied with force-sensing irrigation catheter (target LSI 6-6.5) to abolish all the DZs and LPs discovered at baseline. After the first lesion set a re-map was performed looking for persistent DZs or LPs in the same LV segment (residual) or the appearance in a new ones (shift) in a 17-segment LV model; additional RF lesions and maps were performed only if DZs or LPs were still present in the last map. Results Of 28 VT cases considered, 9 patients with detailed LV maps and subsequent remaps were analyzed. Median age was 66 yo, 8 males, 7/9 with ischemic heart disease. In 7/9 patients clinical VTs were also induced and mapped. At baseline ILAM maps identified 24 DZs; after the first lesion set, 9 DZs were still appreciable at the same localization and 9 shifts to another LV segment (e.g. fig1). In 100% of patients at least one DZ was still appreciable at the first remap, while in 78% of patients a shift of the previous one was noted. At remap after a second lesion set 9 DZs were still present (3 residual, 6 shifts) in 33% of pts. Finally after a third lesion set only 2 DZs were still present in the same segment and then abolished. Furthermore, at baseline LPs were present in 28 LV segments, and after the first lesion set LPs were still present in 15 segments (9 residual, 6 new LPs). At first remap 78% of patients still showed LPs. After a second lesion set LPs were still visible in 6 segments (3 residual, 3 shift) in 22% of patients. In the third remap only in 2 segments could still be appreciated (1 residual, 1 shift) and finally were all abolished (summary in fig2). In 5/7 patients the clinical VT isthmus were identified in a DZ at baseline. At median FU of 6 months 7/9 patients has no VT recurrences, while there was one non-cardiovascular death. Conclusions Frequently DZs and LPs persistence is observed after first sets of lesions and additional RF deliveries are required for complete abolition. Remapping often demonstrates that both DZs and LPs move to other adjacent LV segments, likely where they were previously masked.Fig1Fig2

Dual energy for pulmonary vein isolation using dual-energy focal ablation technology integrated with a three-dimensional mapping system: SmartfIRE 3-month results.

Contact force (CF)-sensing radiofrequency (RF) catheters with an ablation index have shown reproducible outcomes for the treatment of atrial fibrillation (AF) in large multicentre studies. A dual-energy (DE) focal CF catheter to deliver RF and unipolar/biphasic pulsed field ablation (PFA), integrated with a three-dimensional (3D) mapping system, can provide operators with additional flexibility. The SmartfIRE study assessed the safety and efficacy of this novel technology for the treatment of drug-refractory, symptomatic paroxysmal AF. Results at 3 months post-ablation are presented here. Pulmonary vein isolation (PVI) was performed using a DE focal, irrigated CF-sensing catheter with the recommendation of PFA at posterior/inferior and RF ablation at the anterior/ridge/carina segments. Irrespective of energy, a tag size of 3 mm; an inter-tag distance ≤6 mm; a target index of 550 for anterior, roof, ridge, and carina; and a target index of 400 for posterior and inferior were recommended. Cavotricuspid isthmus ablation was permitted in patients with documented typical atrial flutter. The primary effectiveness endpoint was acute procedural success. The primary safety endpoint was the rate of primary adverse events (PAEs) within 7 days of the procedure. A prespecified patient subset underwent oesophageal endoscopy (EE; 72 h post-procedure), neurological assessment (NA; pre-procedure and discharge), and cardiac computed tomography (CT)/magnetic resonance angiogram (MRA) imaging (pre-procedure and 3 months post-procedure) for additional safety evaluation, and a mandatory remapping procedure (Day 75 ± 15) for PVI durability assessment. Of 149 patients enrolled between February and June 2023, 140 had the study catheter inserted (safety analysis set) and 137 had ablation energy delivered (per-protocol analysis set). The median (Q1/Q3) total procedure and fluoroscopy times were 108.0 (91.0/126.0) and 4.2 (2.3/7.7) min (n = 137). The acute procedural success rate was 100%. First-pass isolation was achieved in 89.1% of patients and 96.8% of veins. Cavotricuspid isthmus ablations were successfully performed in 12 patients [pulsed field (PF) only: 6, RF only: 5, and RF/PF: 1]. The PAE rate was 4.4% [6/137 patients; 2 pulmonary vein (PV) stenoses, 2 cardiac tamponades/perforations, 1 stroke, and 1 pericarditis]. No coronary artery spasm was reported. No oesophageal lesion was seen in the EE subset (0/31, 0%). In the NA subset (n = 30), microemboli lesions were identified in 2 patients (2/30, 6.7%), both of which were resolved at follow-up; only 1 was symptomatic (silent cerebral lesion, 3.3%). In the CT/MRA subset (n = 30), severe PV narrowing (of >70%) was detected in 2 patients (2/30, 6.7%; vein level 2/128, 1.6%), of whom 1 underwent dilatation and stenting and 1 was asymptomatic; both were associated with high index values and a small inter-tag distance. In the PV durability subset (n = 30), 100/115 treated PVs (87%) were durably isolated and 18/30 patients (60.0%) had all PVs durably isolated. A DE focal CF catheter with 3D mapping integration showed a 100% acute success rate with an acceptable safety profile in the treatment of paroxysmal AF. Prespecified 3-month remapping showed notable PVI durability. ClinicalTrials.gov Identifier: NCT05752487.