Predicting and Recognizing Drug-Induced Type I Brugada Pattern Using ECG-Based Deep Learning.

BACKGROUND: Brugada syndrome (BrS) has been associated with sudden cardiac death in otherwise healthy subjects, and drug-induced BrS accounts for 55% to 70% of all patients with BrS. This study aims to develop a deep convolutional neural network and evaluate its performance in recognizing and predicting BrS diagnosis. METHODS AND RESULTS: Consecutive patients who underwent ajmaline testing for BrS following a standardized protocol were included. ECG tracings from baseline and during ajmaline were transformed using wavelet analysis and a deep convolutional neural network was separately trained to (1) recognize and (2) predict BrS type I pattern. The resultant networks are referred to as BrS-Net. A total of 1188 patients were included, of which 361 (30.3%) patients developed BrS type I pattern during ajmaline infusion. When trained and evaluated on ECG tracings during ajmaline, BrS-Net recognized a BrS type I pattern with an AUC-ROC of 0.945 (0.921-0.969) and an AUC-PR of 0.892 (0.815-0.939). When trained and evaluated on ECG tracings at baseline, BrS-Net predicted a BrS type I pattern during ajmaline with an AUC-ROC of 0.805 (0.845-0.736) and an AUC-PR of 0.605 (0.460-0.664). CONCLUSIONS: BrS-Net, a deep convolutional neural network, can identify BrS type I pattern with high performance. BrS-Net can predict from baseline ECG the development of a BrS type I pattern after ajmaline with good performance in an unselected population.

Advancing Surgical Arrhythmia Ablation: Novel Insights on 3D Printing Applications and Two Biocompatible Materials.

To date, studies assessing the safety profile of 3D printing materials for application in cardiac ablation are sparse. Our aim is to evaluate the safety and feasibility of two biocompatible 3D printing materials, investigating their potential use for intra-procedural guides to navigate surgical cardiac arrhythmia ablation. Herein, we 3D printed various prototypes in varying thicknesses (0.8 mm-3 mm) using a resin (MED625FLX) and a thermoplastic polyurethane elastomer (TPU95A). Geometrical testing was performed to assess the material properties pre- and post-sterilization. Furthermore, we investigated the thermal propagation behavior beneath the 3D printing materials during cryo-energy and radiofrequency ablation using an in vitro wet-lab setup. Moreover, electron microscopy and Raman spectroscopy were performed on biological tissue that had been exposed to the 3D printing materials to assess microparticle release. Post-sterilization assessments revealed that MED625FLX at thicknesses of 1 mm, 2.5 mm, and 3 mm, along with TPU95A at 1 mm and 2.5 mm, maintained geometrical integrity. Thermal analysis revealed that material type, energy source, and their factorial combination with distance from the energy source significantly influenced the temperatures beneath the 3D-printed material. Electron microscopy revealed traces of nitrogen and sulfur underneath the MED625FLX prints (1 mm, 2.5 mm) after cryo-ablation exposure. The other samples were uncontaminated. While Raman spectroscopy did not detect material release, further research is warranted to better understand these findings for application in clinical settings.

Genetic Testing in Brugada Syndrome: A 30-Year Experience.

BACKGROUND: A pathogenic/likely pathogenic variant can be found in 20% to 25% of patients with Brugada syndrome (BrS) and a pathogenic/likely pathogenic variant in SCN5A is associated with a worse prognosis. The aim of this study is to define the diagnostic yield of a large gene panel with American College of Medical Genetics and Genomics variant classification and to assess prognosis of SCN5A and non-SCN5A variants. METHODS: All patients with BrS, were prospectively enrolled in the Universitair Ziekenhuis Brussel registry between 1992 and 2022. Inclusion criteria for the study were (1) BrS diagnosis; (2) genetic analysis performed with a large gene panel; (3) classification of variants following American College of Medical Genetics and Genomics guidelines. Patients with a pathogenic/likely pathogenic variant in SCN5A were defined as SCN5A+. Patients with a reported variant in a non-SCN5A gene or with no reported variants were defined as patients with SCN5A-. All variants were classified as missense or predicted loss of function. RESULTS: A total of 500 BrS patients were analyzed. A total of 104 patients (20.8%) were SCN5A+ and 396 patients (79.2%) were SCN5A-. A non-SCN5A gene variant was found in 75 patients (15.0%), of whom, 58 patients (77.3%) had a missense variant and 17 patients (22.7%) had a predicted loss of function variant. At a follow-up of 84.0 months, 48 patients (9.6%) experienced a ventricular arrhythmia (VA). Patients without any variant had higher VA-free survival, compared with carriers of a predicted loss of function variant in SCN5A+ or non-SCN5A genes. There was no difference in VA-free survival between patients without any variant and missense variant carriers in SCN5A+ or non-SCN5A genes. At Cox analysis, SCN5A+ or non-SCN5A predicted loss of function variant was an independent predictor of VA. CONCLUSIONS: In a large BrS cohort, the yield for SCN5A+ is 20.8%. A predicted loss of function variant carrier is an independent predictor of VA.

Pericarditis prophylactic therapy after sinus node-sparing hybrid ablation for inappropriate sinus tachycardia/postural orthostatic sinus tachycardia.

Background: Pericarditis is the most common complication following hybrid sinus node-sparing ablation for inappropriate sinus tachycardia (IST)/postural orthostatic tachycardia syndrome (POTS). Objective: The study sought to evaluate the association of prophylaxis therapy on the risk of symptomatic pericarditis following hybrid IST/POTS ablation. Methods: All consecutive patients undergoing to hybrid ablation of symptomatic IST/POTS refractory or intolerant to drugs were retrospectively analyzed. Pharmacological prophylaxis therapy was based on acetylsalicylic acid and colchicine started on the day of the ablation and continued for at least 3 months. The primary endpoint was occurrence of symptomatic pericarditis. The secondary endpoint was occurrence of pericarditis-related complications, including the following: duration of pericarditis >3 months, hospitalization for pericarditis, postpericardiectomy pleuro-pericarditis, and pericardiectomy. Results: A total of 220 patients undergone to hybrid IST/POTS ablation were included and 44 (20%) underwent prophylaxis therapy. Pericarditis occurred in 101 (45.9%) patients, with 97 (96%) in the first 5 days. At survival analysis, prophylaxis was associated with higher rate of freedom from pericarditis (81.9% vs 47.2%, log-rank P < .001). Pericarditis-related complications were low, occurring in 7 (3.2%) patients. There was no difference in pericarditis-related complications between the patients who underwent prophylaxis therapy and patients who did not. At Cox multivariate analysis, predictors of pericarditis were IST (vs POTS) (hazard ratio 0.61, 95% confidence interval0.39-0.99, P = .04) and prophylaxis therapy (hazard ratio 0.27, 95% confidence interval 0.13-0.55, P < .001). Conclusion: In a large cohort of patients undergoing hybrid ablation for IST/POTS, a prophylaxis therapy with acetylsalicylic acid and colchicine was associated with a lower rate of symptomatic pericarditis.

Posterior wall isolation via a multi-electrode radiofrequency balloon catheter: feasibility, technical considerations, endoscopic findings and comparison with cryoballoon technologies.

BACKGROUND: Posterior wall (PW) isolation is an important adjunctive ablation target in patients with non-paroxysmal atrial fibrillation (AF). Traditionally performed with point-by-point radiofrequency (RF) ablation, PW isolation has also been performed with different cryoballoon technologies. We aimed at assessing the feasibility of PW isolation with the novel RF balloon catheter Heliostar™ (Biosense Webster, CA, USA). METHODS: We prospectively enrolled 32 consecutive patients with persistent AF scheduled for first-time ablation with the Heliostar™ device. Procedural data were compared with those from 96 consecutive persistent AF patients undergoing pulmonary vein (PV) plus PW isolation with a cryoballoon device. The ratio RF balloon/cryoballoon was 1:3 for each operator involved in the study, aiming at avoiding any imbalance related to different experience. RESULTS: Single-shot PV isolation was documented in a significantly higher number of cases with the RF balloon technology compared to cryoballoon ablation (89.8% vs. 81.0%; p = 0.02, respectively). PW isolation was achieved with a similar number of balloon applications between the two groups (11 ± 4 with the RF balloon versus 11 ± 2 with the cryoballoon; p = 0.16), but in a significantly shorter time among RF balloon patients (228 ± 72 s versus 1274 ± 277 s with cryoballoon; p < 0.001). Primary safety endpoint occurred in none of the RF balloon patients versus 5 (5.2%) patients in the cryoballoon group (p = 0.33). Primary efficacy endpoint was achieved in all (100%) RF balloon patients versus 93 (96.9%) cryoballoon ones (p = 0.57). Oesophageal endoscopy did not show any signs of thermal lesions in RF balloon patients with luminal temperature rise. CONCLUSIONS: RF balloon-based PW isolation was safe and promoted shorter procedure times compared to similar cryoballoon-based ablation procedures.

Coronary artery disease in atrial fibrillation ablation: impact on arrhythmic outcomes.

AIMS: Catheter ablation (CA) is an established treatment for atrial fibrillation (AF). A computed tomography (CT) may be performed before ablation to evaluate the anatomy of pulmonary veins. The aim of this study is to investigate the prevalence of patients with coronary artery disease (CAD) detected by cardiac CT scan pre-ablation and to evaluate the impact of CAD and revascularization on outcomes after AF ablation. METHODS AND RESULTS: All consecutive patients with AF diagnosis, hospitalized at Universitair Ziekenhuis Brussel, Belgium, between 2015 and 2019, were prospectively screened for enrolment in the study. Inclusion criteria were (i) AF diagnosis, (ii) first procedure of AF ablation with cryoballoon CA, and (iii) contrast CT scan performed pre-ablation. A total of 576 consecutive patients were prospectively included and analysed in this study. At CT scan, 122 patients (21.2%) were diagnosed with CAD, of whom 41 patients (7.1%) with critical CAD. At survival analysis, critical CAD at CT scan was a predictor of atrial tachyarrhythmia (AT) recurrence during the follow-up, only in Cox univariate analysis [hazard ratio (HR) = 1.79] but was not an independent predictor in Cox multivariate analysis. At Cox multivariate analysis, independent predictors of AT recurrence were as follows: persistent AF (HR = 2.93) and left atrium volume index (HR = 1.04). CONCLUSION: In patients undergoing CT scan before AF ablation, critical CAD was diagnosed in 7.1% of patients. Coronary artery disease and revascularization were not independent predictors of recurrence; thus, in this patient population, AF ablation should not be denied and can be performed together with CAD treatment.

Redo procedures after sinus node sparing hybrid ablation for inappropriate sinus tachycardia/postural orthostatic sinus tachycardia.

AIMS: A novel sinus node (SN) sparing hybrid ablation for inappropriate sinus node tachycardia (IST)/postural orthostatic tachycardia syndrome (POTS) has been demonstrated to be an effective and safe therapeutic option in patients with symptomatic drug-resistant IST/POTS. The aim of this study was to evaluate the long-term rate of redo procedures after hybrid IST ablation and procedural strategy, outcomes and safety of redo procedures. METHODS AND RESULTS: All consecutive patients from 2015 to 2023 were prospectively enrolled in the UZ Brussel monocentric IST/POTS registry. They were analysed if the following inclusion criteria were fulfilled: 1) diagnosis of IST or POTS, 2) symptomatic IST/POTS refractory or intolerant to drugs, and 3) hybrid SN sparing ablation performed. The primary endpoint was redo procedure. The primary safety endpoint was pacemaker (PM) implantation. A total of 220 patients undergone to hybrid IST ablation were included, 185 patients (84.1%) were treated for IST and 61 patients (27.7%) for POTS.After a follow-up of 73.3 ± 16.2 months, 34 patients (15.4%) underwent a redo. A total of 23 patients (67.6%) had a redo for IST recurrence and 11 patients (32.4%) for other arrhythmias. Pacemaker implantation was performed in 21 patients (9.5%). Nine patients (4.1%) had no redo procedure and experienced sick sinus syndrome requiring a PM. Twelve patients (5.4%) received a PM as a shared therapeutic choice combined with SN ablation procedure. CONCLUSION: In a large cohort of patients the long-term free survival from redo procedure after hybrid IST ablation was 84.6% with a low PM implantation rate.

Safety of the Radiofrequency Balloon for Pulmonary Vein Isolation: A Focus on Lesion Metric Analysis of Posterior Electrodes.

Previous clinical studies on pulmonary vein isolation (PVI) with radiofrequency balloons (RFB) reported safe and effective procedures for a 20 s RF delivery via posterior electrodes. Recent recommendations from the manufacturer suggest reducing the application time to 15 s on the posterior wall (PW) when facing the esophagus region. Here, we retrospectively assess whether 15 s of RF delivery time on posterior electrodes is safe while still ensuring lesion metrics of sufficient quality. This retrospective study included 133 patients with paroxysmal and persistent atrial fibrillation who underwent PVI using an RFB (Heliostar, Biosense Webster, Inc., Irvine, CA, USA) at two European centers. The ablation protocol was set for an RF duration of 20 s/60 s for the posterior/anterior electrodes. A multielectrode temperature probe was systematically used. In the case of an esophageal temperature rise (ETR) above 42 °C (ETR+), an endoscopic evaluation was performed. All posterior electrode lesion metric dynamics (temperature (T) and impedance (Z)) were collected from the RFB generator and analyzed offline. In total, 2435 posterior electrode applications were analyzed. With an RF delivery of 19.8 (19.7-19.8) s, the median impedance drop was 18.4 (12.2-25.2) Ω, while the temperature rise was 11.1 (7.1-14.9) °C. Accordingly, impedance (84.6 (79.3-90.2) Ω) and temperature plateaus (38 (35.3-41.1) °C) were reached at 13.9 (10.6-16) s and 16.4 (12.6-18.5) s, respectively. Overall, 99.6% and 95.8% of electrodes reached 90% (16.6 Ω) and 95% (17.5 Ω) of their impedance drops within 15 s of RF delivery, while 97.2% and 92.8% achieved 90% (34.2 °C) and 95% (36.1 °C) of their temperature rise to reach the plateaus within 15 s of RF delivery. An ETR >42 °C occurred in 37 (30.1%) patients after 17.7 ± 2.3 s of RF delivery. In the ETR+ group, the impedance drop and temperature rise on the posterior electrodes were higher compared to patients where ETR was <42 °C. Two asymptomatic thermal esophageal injuries were observed. In conclusion, 15 s of RF delivery on the posterior electrodes provides a good balance between safety, with no esophageal temperature rise, and efficacy with high-profile lesion metrics.

3D mapping challenges in hybrid video-assisted thoracoscopic surgical ablation of Brugada syndrome.

OBJECTIVES: Brugada syndrome is a life-threatening disease with an arrhythmogenic substrate located in the epicardium of right ventricle outflow tract. Therefore, the correct region identification is crucial for a successful ablation procedure. Various mapping techniques can be adopted to elaborate this issue, but they were all initially developed for endovascular use. METHODS: In this study, we analysed 21 consecutive hybrid video-assisted thoracoscopic ablation of Brugada syndrome, performed using different mapping systems to identify the ablation target and confirm the elimination of arrhythmogenic substrate; 35 maps have been analysed. RESULTS: Acute success of epicardial right ventricle outflow tract ablation has been achieved in 100% of procedures, no periprocedural complications have been observed; HD Grid catheter showed higher area identification speed and faster fractionated potentials visualization; Rhythmia system has demonstrated the best map density; Carto 3 system showed a significant advantage in patient preparation time, but mapping speed was reduced due to focal catheter use only. CONCLUSIONS: All tested electro anatomical mapping systems can be used for hybrid video-assisted thoracoscopic ablation with same clinical success; however, accuracy and efficacy of mapping systems are heterogenous and highly dependent on proper patient preparation, mapping system and physician skills.

Outcomes of pulmonary vein isolation with radiofrequency balloon vs. cryoballoon ablation: a multi-centric study.

AIMS: Cryoballoon (CB) ablation is the mainstay of single-shot pulmonary vein isolation (PVI). A radiofrequency balloon (RFB) catheter has recently emerged as an alternative. However, these two technologies have not been compared. This study aims to evaluate the freedom from atrial tachyarrhythmias (ATas) at 1 year: procedural characteristics, efficacy, and safety of the novel RFB compared with CB for PVI in patients with paroxysmal atrial fibrillation (AF). METHODS AND RESULTS: This prospective multi-centre study included consecutive patients with symptomatic drug-resistant paroxysmal AF who underwent PVI with RFB or CB between July 2021 and January 2022 from three European centres. A total of 375 consecutive patients were included, 125 in the RFB group and 250 in the CB. Both groups had comparable clinical characteristics. At 12.33 ± 4.91 months, ATas-free rates were 83.20% and 82.00% in the RFB and CB groups, respectively (P > 0.05). Compared with the CB group, the RFB group showed a shorter procedure time [59.91 (45.80-77.12) vs. 77.0 (35.13-122.71) min (P < 0.001)], dwell time [19.59 (14.41-30.24) vs. 27.03 (17.11-57.21) min (P = 0.04)], time to isolation, and thermal energy delivery in all pulmonary veins (P < 0.001). First-pass isolation was comparable. No major complications occurred in either group, with no stroke, atrio-oesophageal fistula, or permanent phrenic nerve injury. Transient phrenic nerve palsy occurred more frequently with CB than RFB (7.20% vs. 3.20%; P = 0.02). Oesophageal temperature rise occurred in 21 (16.8%) patients in the RFB group, and gastroscopy showed erythema in two of them with complete recovery after 30 days. CONCLUSIONS: The RFB appears to have a safety and efficacy profile similar to that of the CB for PVI. Shorter procedural times appear to be driven by shorter left atrial dwell and thermal delivery times.

Compatibility assessment of a temperature-controlled radiofrequency catheter with a novel electroanatomical mapping system.

Background: The novel DiamondTemp ablation system (DTA) and EnSiteX mapping System (EAM) are both CE-Marked and FDA approved medical devices. The DTA has been validated by its manufacturer only in combination with previous version of EnSite System-EnSite Precision. The aim of this study was to evaluate compatibility of DTA with EnSite X with a previously developed protocol. Methods: Three configurations were tested: 3.1. Medtronic Generator connection Box (GCB) and AmpereConnect cable; 3.2. the Medtronic GCB-E and electrogram out cable from GCB to EAM; 3.3. Direct connection of DTA to EAM using intracardiac out cable with no GCB. Results: The previously developed universal method for compatibility assessment of ablation catheters and navigation systems was used with success for assessing DTA and EnSite X EAM compatibility, with reproducible results. Accuracy of DTA visualization with different setups was evaluated with a phantom model measuring distances between DTA and reference points. DTA is compatible with EnSiteX EAM with a safety and reliability profile guaranteed, if within the described specifications. In particular, careful setup is mandatory to achieve good clinical outcomes as only setup 3.2 is viable for both NavX and Voxel Mode and demonstrated satisfactory results and accuracy. Setup 3.3 showed a significant shift immediately after catheter insertion. Catheter position was away from baseline points and the dislocation increased during the radiofrequency delivery. Conclusions: Previously developed method for compatibility assessment of ablation catheters and navigation systems has been used for a new EAM. DTA is compatible with EnSiteX EAM with proper configuration.

Hybrid atrial fibrillation ablation: long-term outcomes from a single-centre 10-year experience.

AIMS: Hybrid atrial fibrillation (AF) ablation is a promising approach in non-paroxysmal AF. The aim of this study is to assess the long-term outcomes of hybrid ablation in a large cohort of patients after both an initial and as a redo procedure. METHODS AND RESULTS: All consecutive patients undergoing hybrid AF ablation at UZ Brussel from 2010 to 2020 were retrospectively evaluated. Hybrid AF ablation was performed in a one-step procedure: (i) thoracoscopic ablation followed by (ii) endocardial mapping and eventual ablation. All patients received PVI and posterior wall isolation. Additional lesions were performed based on clinical indication and physician judgement. Primary endpoint was freedom from atrial tachyarrhythmias (ATas). A total of 120 consecutive patients were included, 85 patients (70.8%) underwent hybrid AF ablation as first procedure (non-paroxysmal AF 100%), 20 patients (16.7%) as second procedure (non-paroxysmal AF 30%), and 15 patients (12.5%) as third procedure (non-paroxysmal AF 33.3%). After a mean follow-up of 62.3 months ± 20.3, a total of 63 patients (52.5%) experienced ATas recurrence. Complications occurred in 12.5% of patients. There was no difference in ATas between patients undergoing hybrid as first vs. redo procedure (P = 0.53). Left atrial volume index and recurrence during blanking period were independent predictors of ATas recurrence. CONCLUSION: In a large cohort of patients undergoing hybrid AF ablation, the survival from ATas recurrence was 47.5% at ≈5 years follow-up. There was no difference in clinical outcomes between patients undergoing hybrid AF ablation as first procedure or as a redo.

Genetic testing in children with Brugada syndrome: results from a large prospective registry.

AIMS: A pathogenic/likely pathogenic (P/LP) variant in SCN5A is found in 20-25% of patients with Brugada syndrome (BrS). However, the diagnostic yield and prognosis of gene panel testing in paediatric BrS is unclear. The aim of this study is to define the diagnostic yield and outcomes of SCN5A gene testing with ACMG variant classification in paediatric BrS patients compared with adults. METHODS AND RESULTS: All consecutive patients diagnosed with BrS, between 1992 and 2022, were prospectively enrolled in the UZ Brussel BrS registry. Inclusion criteria were: (i) BrS diagnosis; (ii) genetic analysis performed with a large gene panel; and (iii) classification of gene variants following ACMG guidelines. Paediatric patients were defined as ≤16 years of age. The primary endpoint was ventricular arrhythmias (VAs). A total of 500 BrS patients were included, with 63 paediatric patients and 437 adult patients. Among children with BrS, 29 patients (46%) had a P/LP variant (P+) in SCN5A and no variants were found in 34 (54%) patients (P-). After a mean follow-up of 125.9 months, 8 children (12.7%) experienced a VA, treated with implanted cardioverter defibrillator shock. At survival analysis, P- paediatric patients had higher VA-free survival during the follow-up, compared with P+ paediatric patients. P+ status was an independent predictor of VA. There was no difference in VA-free survival between paediatric and adult BrS patients for both P- and P+. CONCLUSION: In a large BrS cohort, the diagnostic yield for P/LP variants in the paediatric population is 46%. P+ children with BrS have a worse arrhythmic prognosis.

Pulmonary vein isolation with the radiofrequency balloon catheter: a single centre prospective study.

AIMS: The multielectrode radiofrequency balloon catheter (RFB) has been developed to achieve safe and effective pulmonary vein isolation (PVI) for atrial fibrillation (AF) ablation. This single-centre study aimed to evaluate the midterm clinical outcome and predictors of single-shot PVI with the novel RFB. METHODS AND RESULTS: All consecutive patients with symptomatic paroxysmal or persistent AF undergoing first-time PVI with the RFB were prospectively included. Clinical and procedural parameters were systematically collected. The primary safety endpoint was defined as any major periprocedural complications. The primary efficacy endpoint consisted of freedom from any atrial tachyarrhythmias (ATas) lasting >30 s during the follow-up after a 3-month blanking period. Persistent single-shot PVI was defined as PVI achieved with a single RFB application without acute reconnection. A total of 104 consecutive patients (mean age 64.3 ± 11.4 years, 56.7% males) were included. 15 patients (14.4%) presented with persistent AF. The procedure time was 59.0 min with a dwell time of 20.0 min. One major complication occurred in one patient. At a mean follow-up of 10.1 ± 5.3 months, freedom from ATas was 82.9%. ATas occurred in 14 patients, 11/69 patients (15.9%) with paroxysmal AF and 3/13 (23.1%) with persistent AF. The best cut-offs to predict persistent single-shot PVI were impedance drop >19.2 Ω [area under the receiver operator characteristic curve (AUC) 0.74] and temperature rise >11.1° C (AUC 0.77). CONCLUSION: In a large cohort of patients undergoing PVI with the RFB, the complication rate was 1%. At a mid-term follow-up of 10.1 ± 5.3 months, freedom from ATas was 82.9%. Specific cut-offs of impedance drop and temperature rise may be useful to predict persistent single-shot isolation.

3D-Printed Biomaterial Testing in Response to Cryoablation: Implications for Surgical Ventricular Tachycardia Ablation.

Background: The lack of thermally and mechanically performant biomaterials represents the major limit for 3D-printed surgical guides, aimed at facilitating complex surgery and ablations. Methods: Cryosurgery is a treatment for cardiac arrhythmias. It consists of obtaining cryolesions, by freezing the target tissue, resulting in selective and irreversible damage. MED625FLX and TPU95A are two biocompatible materials for surgical guides; however, there are no data on their response to cryoenergy delivery. The study purpose is to evaluate the biomaterials' thermal properties, examining the temperature changes on the porcine muscle samples (PMS) when the biomaterials are in place during the cryoablation. Two biomaterials were selected, MED625FLX and TPU95A, with two thicknesses (1.0 and 2.5 mm). To analyze the biomaterials' behavior, the PMS temperatures were measured during cryoablation, firstly without biomaterials (control) and after with the biomaterials in place. To verify the biomaterials' suitability, the temperatures under the biomaterial samples should not exceed a limit of -30.0 °C. Furthermore, the biomaterials' geometry after cryoablation was evaluated using the grid paper test. Results: TPU95A (1.0 and 2.5 mm) successfully passed all tests, making this material suitable for cryoablation treatment. MED625FLX of 1.0 mm did not retain its shape, losing its function according to the grid paper test. Further, MED625FLX of 2.5 mm is also suitable for use with a cryoenergy source. Conclusions: TPU95A (1.0 and 2.5 mm) and MED625FLX of 2.5 mm could be used in the design of surgical guides for cryoablation treatment, because of their mechanical, geometrical, and thermal properties. The positive results from the thermal tests on these materials and their thickness prompt further clinical investigation.

Evaluation of photogrammetry for medical application in cardiology.

Background: In the field of medicine, photogrammetry has played for long time a marginal role due to the significant amount of work required that made it impractical for an extended medical use. Developments in digital photogrammetry occurred in the recent years, that have steadily increased the interest and application of this technique. The present study aims to compare photogrammetry reconstruction of heart with computed tomography (CT) as a reference. Methods: The photogrammetric reconstructions of digital images from ECG imaging derived images were performed. In particular, the ventricles of 15 patients with Brugada syndrome were reconstructed by using the free Zephyr Lite software. In order to evaluate the accuracy of the technique, measurements on the reconstructions were compared to patient-specific CT scan imported in ECG imaging software UZBCIT. Result: The results showed that digital photogrammetry in the context of ventricle reconstruction is feasible. The photogrammetric derived measurements of ventricles were not statistically different from CT scan measurements. Furthermore, the analysis showed high correlation of photogrammetry reconstructions with CT scan and a correlation coefficient close to 1. Conclusion: It is possible to reproduce digital objects by photogrammetry if the process described in this study is performed. The reconstruction of the ventricles from CT scan was very close to the values of the respective photogrammetric reconstruction.

Heart rate variability and microvolt T wave alternans changes during ajmaline test may predict prognosis in Brugada syndrome.

PURPOSE: Drug-induced type I Brugada syndrome (BrS) is associated with a ventricular arrhythmia (VA) rate of 1 case per 100 person-years. This study aims to evaluate changes in electrocardiographic (ECG) parameters such as microvolt T wave alternans (mTWA) and heart rate variability (HRV) at baseline and during ajmaline testing for BrS diagnosis. METHODS: Consecutive patients diagnosed with BrS during ajmaline testing with 5-year follow-up were included in this study. For comparison, a negative ajmaline control group and an isoproterenol control group were also included. ECG recordings during ajmaline or isoproterenol test were divided in two timeframes from which ECG parameters were calculated: a 5-min baseline timeframe and a 5-min drug timeframe. RESULTS: A total of 308 patients with BrS were included, 22 (0.7%) of which suffered VAs during follow-up. One hundred patients were included in both isoproterenol and negative ajmaline control groups. At baseline, there was no difference in ECG parameters between control groups and patients with BrS, nor between BrS with and without VAs. During ajmaline testing, BrS with VAs presented longer QRS duration [159 ± 34 ms versus 138 (122-155) ms, p = 0.006], higher maximum mTWA [33.8 (14.0-114) µV versus 8.00 (3.67-28.2) µV, p = 0.001], and lower power in low frequency band [25.6 (5.8-53.8) ms2 versus 129.5 (52.7-286) ms2, p < 0.0001] when compared to BrS without VAs. CONCLUSIONS: Ajmaline induced important HRV changes similar to those observed during isoproterenol. Increased mTWA was observed only in patients with BrS. BrS with VAs during follow-up presented worse changes during ajmaline test, including lower LF power and higher maximum mTWA which were independent predictors of events.

A 3D-printed surgical guide for ischemic scar targeting and ablation.

Background: 3D printing technology development in medical fields allows to create 3D models to assist preoperative planning and support surgical procedures. Cardiac ischemic scar is clinically associated with malignant arrhythmias. Catheter ablation is aimed at eliminating the arrhythmogenic tissue until the sinus rhythm is restored. The scope of this work is to describe the workflow for a 3D surgical guide able to define the ischemic scar and target catheter ablation. Materials and methods: For the patient-specific 3D surgical guide and 3D heart phantom model realization, both CT scan and cardiac MRI images were processed; this was necessary to extract anatomical structures and pathological information, respectively. Medical images were uploaded and processed in 3D Slicer. For the surgical guide modeling, images from CT scan and MRI were loaded in Meshmixer and merged. For the heart phantom realization, only the CT segmentation was loaded in Meshmixer. The surgical guide was printed in MED625FLX with Polyjet technology. The heart phantom was printed in polylactide with FDM technology. Results: 3D-printed surgical model was in agreement with prespecified imputed measurements. The phantom fitting test showed high accuracy of the 3D surgical tool compared with the patient-specific reproduced heart. Anatomical references in the surgical guide ensured good stability. Ablation catheter fitting test showed high suitability of the guide for different ablation tools. Conclusion: A 3D-printed guide for ventricular tachycardia ablation is feasible and accurate in terms of measurements, stability, and geometrical structure. Concerning clinical use, further clinical investigations are eagerly awaited.

Development of a 3D printed surgical guide for Brugada syndrome substrate ablation.

Background: Brugada syndrome (BrS) is a disease associated with ventricular arrhythmias and sudden cardiac death. Epicardial ablation has demonstrated high therapeutic efficacy in preventing ventricular arrhythmias. The purpose of this research is to define a workflow to create a patient-specific 3D-printed tool to be used as a surgical guide for epicardial ablation in BrS. Methods: Due to their mechanical properties and biocompatibility, the MED625FLX and TPU95A were used for cardiac 3D surgical guide printing. ECG imaging was used to define the target region on the right ventricular outflow tract (RVOT). CT scan imaging was used to design the model based on patient anatomy. A 3D patient-specific heart phantom was also printed for fitting test. Sterilization test was finally performed. Results: 3D printed surgical models with both TPU95A and MED625FLX models were in agreement with pre-specified imputed measurements. The phantom test showed retention of shape and correct fitting of the surgical tool to the reproduced phantom anatomy, as expected, for both materials. The surgical guide adapted to both the RVOT and the left anterior descending artery. Two of the 3D models produced in MED265FLX showed damage due to the sterilization process. Conclusions: A 3D printed patient-specific surgical guide for epicardial substrate ablation in BrS is feasible if a specific workflow is followed. The design of the 3D surgical guide ensures proper fitting on the heart phantom with good stability. Further investigations for clinical use are eagerly awaited.

Temperature analysis of 3D-printed biomaterials during unipolar and bipolar radiofrequency ablation procedure.

Background: Due to their mechanical properties, the MED625FLX and TPU95A could be appropriate candidates for cardiac 3D surgical guide use during radiofrequency ablation (RFA) treatment. Methods: RFA aims to destroy the heart tissue, which cause arrhythmias, by applying a radiofrequency (RF) energy at critical temperature above +50.0°C, where the thermal damage is considered not reversible. This study aims to analyze the biomaterials thermal properties with different thicknesses, by testing the response to bipolar and unipolar RFA on porcine muscle samples (PMS), expressed in temperature. For the materials evaluation, the tissue temperature during RFA applications was recorded, firstly without (control) and after with the biomaterials in position. The biomaterials were considered suitable for the RFA treatment if: (1) the PMS temperatures with the samples were not statistically different compared with the control; (2) the temperatures never reached the threshold; (3) no geometrical changes after RFA were observed. Results: Based on these criteria, none of the tested biomaterials resulted appropriate for unipolar RFA and the TPU95A failed almost all thermal tests also with the bipolar RFA. The 1.0 mm MED625FLX was modified by bipolar RFA in shape, losing its function. Instead, the 2.5 mm MED625FLX was considered suitable for bipolar RFA catheter use only. Conclusions: The 2.5 mm MED625FLX could be used, in the design of surgical guides for RFA bipolar catheter only, because of mechanical, geometrical, and thermal properties. None of biomaterials tested are appropriate for unipolar ablation catheter because of temperature concerns. Further investigations for clinical use are eagerly awaited.