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

AIMS: 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. METHODS AND RESULTS: 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. CONCLUSION: 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. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05752487.

Repeat pulmonary vein isolation in patients with atrial fibrillation: low ablation index is associated with increased risk of recurrent arrhythmia.

OBJECTIVES: We aimed to investigate the predictors of recurrent arrhythmia after repeated pulmonary vein isolation (PVI) performed in the era of contact force without additional substrate ablation. One of the predictors studied, ablation index (AI), incorporates power, contact force, and time in a weighted formula and is reported to predict lesion size in animals. Design. Consecutive patients (n = 108) undergoing repeat PVI without additional substrate modification using a contact force sensing catheter were included retrospectively at a tertiary center. All ablation points were analyzed offline. A new variable, normalized AI (AI corrected for the location of the lesion-anterior vs. posterior) was calculated. The patients were systematically followed with clinical visit and 12-lead ECG as well as review of the regional electronic patient files at 3 and 12 months after the procedure with 5-day Holter at 12 months. Results. Electrical reconnection to at least one pulmonary vein (PV) was seen in 97% of the patients. The recurrence rate was 35%. There was no recurrence in patients with nAI above 1.15 (n = 26). Patients with electrical reconnection of up to two PVs had a higher risk of recurrence compared with patients having electrical reconnection of three or four PVs (p = .003), and this risk was especially high in patients with persistent atrial fibrillation (69 [39-91]%). Conclusions. The risk of recurrence is higher in patients with ablations performed with low levels of AI and in patients with reconnection to up to two PVs. Our data may indicate the need for higher target levels of AI during repeat PVI than normally used during de-novo PVI.

A randomized trial of contact force in atrial flutter ablation.

AIMS: Contact force (CF) sensing has emerged as a tool to guide and improve outcomes for catheter ablation (CA) for cardiac arrhythmias. The clinical benefit on patient outcomes remains unknown. To study whether CF-guided CA for typical atrial flutter (AFL) is superior to CA not guided by CF. METHODS AND RESULTS: In a double-blinded controlled superiority trial, we randomized patients 1:1 to receive CA for typical AFL guided by CF (intervention group) or blinded to CF (control group). In the intervention group, a specific value of the lesion size index (LSI), estimating ablation lesions size was targeted for each ablation lesion. Patients underwent electrophysiological study (EPS) after 3 months to assess occurrence of the primary endpoint of re-conduction across the cavo-tricuspid isthmus (CTI). We included 156 patients with typical AFL, median age was 68 [interquartile range (IQR) 61-74] years and 120 (77%) patients were male. At index procedure median LSI was higher in the intervention group [6.4 (IQR 5.1-7) vs. 5.6 (IQR 4.5-6.9), P < 0.0001]. After 3 months, 126 patients (58 in intervention group) underwent EPS for primary endpoint assessment. Thirty (24%) patients had CTI re-conduction, distributed with 15 patients in each treatment group (P = 0.62). We observed no difference between treatment groups with regard to fluoroscopy, ablation, or procedure times, nor peri-procedural complications. CONCLUSION: Contact force-guided ablation does not reduce re-conduction across the CTI after 3 months, nor does CF-guided ablation shorten fluoroscopy, ablation, or total procedure times.

Radiofrequency ablation lesions in low-, intermediate-, and normal-voltage myocardium: an in vivo study in a porcine heart model.

AIMS: Contact force (CF) between radiofrequency (RF) ablation catheter and myocardium and ablation index (AI) correlates with RF lesion depth and width in normal-voltage (>1.5 mV) myocardium (NVM). We investigate the impact of CF on RF lesion depth and width in low (<0.5 mV) (LVM) and intermediate-voltage (0.5-1.5 mV) myocardium (IVM) following myocardial infarction. Correlation between RF lesion depth and width evaluated by native contrast magnetic resonance imaging (ncMRI) and gross anatomical evaluation was investigated. METHODS AND RESULTS: Twelve weeks after myocardial infarction, 10 pigs underwent electroanatomical mapping and endocardial RF ablations were deployed in NVM, IVM, and LVM myocardium. In vivo ncMRI was performed before the heart was excised and subjected to gross anatomical evaluation. Ninety (82%) RF lesions were evaluated. Radiofrequency lesion depth and width were smaller in IVM and LVM compared with NVM (P < 0.001). Radiofrequency lesion depth and width correlated with CF, AI, and impedance drop in NVM (CF and AI P < 0.001) and IVM (CF and AI depths P < 0.001; CF and AI widths P < 0.05). Native contrast magnetic resonance imaging evaluated RF lesion depth and width correlated with gross anatomical depth and width (NVM and IVM P < 0.001; LVM P < 0.05). CONCLUSIONS: Radiofrequency lesions deployed by similar duration, power and CF are smaller in IVM and LVM than in NVM. Radiofrequency lesion depth and width correlated with CF, AI, and impedance drop in NVM and IVM but not in LVM. Native contrast magnetic resonance imaging may be useful to assess RF lesion depth and width in NVM, IVM, and LVM.

Outcome after catheter ablation for left atrial flutter.

Objectives. Left atrial flutter has been reported in up to 10% of patients following pulmonary vein isolation or cardiac surgery. Left atrial flutter is typically highly symptomatic, responds poorly to medical antiarrhythmic treatment, and is often treated by catheter ablation. We aimed to investigate midterm freedom from recurrent arrhythmia after catheter ablation for left atrial flutter. Design. In the National Danish Ablation Registry, we identified consecutive patients, who had undergone catheter ablation for left atrial flutter between 1 January 2014 and 1 April 2017 at our centre. Results. A total of 53 patients (median age 68 years (IQR 60-71) 37 (70%) male) were included. Forty-two patients had prior left atrial catheter ablation procedures (79%), one patient prior ablation for classic atrial flutter (2%), four patients had prior surgery for congenital heart disease (8%), and six patients (11%) had no previous cardiac intervention. Acute procedural success, defined as non-inducibility of any atrial arrhythmia, was achieved in 45 of 53 patients (85%). During midterm follow-up (mean 20 ± 12 months), 26 patients experienced an episode of recurrent atrial arrhythmia. Median EHRA-score was 3 (range 2-4) before catheter ablation and reduced to median 1 (range 1-3) evaluated at follow-up visits after three and twelve months (both p < .001, Wilcoxon rank test). Conclusion. Left atrial flutter is preceded by catheter ablation or cardiac surgery in 89% of patients. Acute procedural success is achieved in majority of patients and ablation reduces symptoms effectively. During midterm follow-up, almost half the patients experience recurrent atrial arrhythmia.

Recurrence after pulmonary vein isolation is associated with low contact force.

OBJECTIVES: Recurrent arrhythmia after pulmonary vein isolation (PVI) by radiofrequency (RF) ablation in patients with atrial fibrillation (AFIB) remains a significant challenge. Using contact force (CF) sensing ablation catheters, we aimed to identify procedure related parameters associated with recurrence after de-novo PVI in patients with AFIB. METHODS: Consecutive patients undergoing a de-novo PVI procedure (n = 120, 63% paroxysmal and 37% persistent AFIB) employing a force-sensing ablation catheter were included. A clinical control including electrocardiogram and 120 hour of Holter-recording at 12-months was performed in all patients. Recurrence was defined as any documented AFIB or atrial flutter more than 30 seconds on Holter-recording after an initial blanking period of three months. RESULTS: Recurrence occurred in 44 patients (37%). Mean CF was lower in patients with recurrent arrhythmia (22.2 ± 9.5 vs. 28.8 ± 9.3 g, p < .001). In multi-variable analyses lower mean CF (OR 0.9 (95% CI 0.8-1.0), p = .03), and higher percentage of ablation time with a CF <10 grams (OR 1.1 (95% CI 1.0-1.1), p = .004) were both associated with recurrence in two distinct models. Dragging during ablation compared with point-by-point ablation technique was associated with recurrence in both models (OR 19.2 (95% CI 2.9-130.0), p = .002, and OR 21.7 (95% CI 2.7-176.2), p = .004). CONCLUSIONS: Low CF and dragging during ablation as compared with point-by-point ablation technique were associated with recurrent arrhythmia in patients with AFIB undergoing de-novo PVI by RF ablation.

Is the knowledge of contact force beneficial in pulmonary vein antrum isolation?

OBJECTIVE: To investigate the effect of the operator knowing the real-time contact force (CF) on the efficacy of pulmonary vein antrum isolation (PVAI). METHODS: Fifty patients with paroxysmal atrial fibrillation (AF) or short lasting persistent AF were randomized to CF guided PVAI (n = 25) or conventional PVAI (n = 25). In the CF guided group, CF between 10 and 40 g was aimed at. Efficacy of PVAI was measured as reduction in AF burden (AFB) and time to AF recurrence detected by implantable cardiac monitor (ICM), inserted three months before PVAI. Blanking period was three months and follow-up 12 months. RESULTS: All pulmonary veins were isolated in the CF guided group and all but one in the conventional group. Mean CF was 25 g in the CF guided group and 24 g in the conventional group (p = 0.75). Compared to pre-ablation, median [IQR] relative reduction in AFB 3-12 months after ablation was 100 [99-100]% in the CF guided group (p < 0.001) and 99.4 [25-100]% in the conventional group (p < 0.001), not different between groups (p = 0.09). Nine patients (36%) had AF recurrence in the CF guided group and 13 (52%) in the conventional group (p = 0.21, log-rank test). CF differed between operators. When adjusted for operator by regression analysis, patients without recurrent AF had lower proportion of ablation time with CF <10 g than recurrent patients (p = 0.034). No complications occurred. CONCLUSIONS: Operator knowledge of real-time CF had no significant effect on AFB reduction or time to AF recurrence. Larger trials should be done to study benefit of real-time CF.

Radiofrequency ablation of accessory pathways in patients with the Wolff-Parkinson-White syndrome: the long-term mortality and risk of atrial fibrillation.

AIMS: To assess the long-term mortality and occurrence of post-ablation atrial fibrillation in patients undergoing a radiofrequency ablation for the Wolff-Parkinson-White (WPW) syndrome. METHODS AND RESULTS: A retrospective cohort study of patients (N = 362) subjected to radiofrequency ablation of the WPW syndrome at Aarhus University Hospital from 1990 to 2011. A comparison cohort (N = 3619) was generated from the Danish National Board of Health Central Population Registry. We found no significant difference in all-cause mortality when comparing the WPW group with the control group [hazard ratio (HR): 0.77 and confidence interval (CI): 0.47-1.25]. After radiofrequency ablation, the WPW group had a significantly higher risk of atrial fibrillation than the control group (HR: 4.77 and CI: 3.05-7.43). Atrial fibrillation prior to ablation (HR: 4.66 and CI: 2.09-10.41) and age over 50 years (HR: 9.79 and CI: 4.29-22.36) at the time of ablation were independent risk factors for post-ablation atrial fibrillation in the WPW group. CONCLUSION: Patients with radiofrequency ablation-treated WPW syndrome have a post-ablation mortality that is similar to the background population. The risk of atrial fibrillation remains high after radiofrequency ablation of the WPW syndrome.

Catheter ablation for ventricular tachycardia in ischaemic heart disease; acute success and long-term outcome.

OBJECTIVES: We conducted a study to assess the acute procedural success and the long-term effect of radiofrequency ablation (RFA) for ventricular tachycardia (VT) in patients with ischaemic heart disease. DESIGN: We included 90 patients with ischaemic heart disease treated with RFA for VT in our institution. Data were obtained from patient files, and implantable cardioverter-defibrillator (ICD) discharges were recorded from in-house and remote follow-up data. Recurrence of VT during follow-up was noted as date of first ICD therapy for VT or first recurrence of symptomatic VT. RESULTS: After the initial RFA procedure no VT was inducible in 42 patients (47%), non-clinical VT was inducible in 21 patients (23%), and the clinical VT was still inducible in 14 patients (16%). The procedural success was indefinable in 13 patients (14%). After a median follow-up of 33 months after the latest RFA, 38 patients (42%) stayed free from recurrent VT. The number of ICD shocks/year was significantly reduced from median 1.1 (interquartile range: 0.3-2.8) to 0 (0-0.4) (p < 0.0001). CONCLUSIONS: Procedural success rate as well as long-term freedom from recurrent VT is modest after RFA for VT in ischaemic heart disease. However, ICD discharges are significantly reduced after RFA, and a considerable proportion of patients remain free from recurrent VT during the long-term follow-up.

Ablation for idiopathic ventricular arrhythmia - with and without arrhythmia-induced cardiomyopathy.

OBJECTIVES: We conducted a study to assess the procedural success and long-term freedom from arrhythmia in patients treated with radiofrequency ablation (RFA) for idiopathic ventricular arrhythmia (VA) with and without arrhythmia-induced cardiomyopathy (AIC). DESIGN: We identified 131 patients treated with RFA for idiopathic VA in our institution; 16 of whom had AIC. Data were obtained from patient files. A questionnaire was used to assess the improvement in subjective symptoms late after RFA. RESULTS: At the initial RFA, any VA was abolished in 93 patients (71%), non-targeted VA still was observed in 5 patients (4%), and the targeted VA remained present in 29 (22%). In 4 patients (3%) procedural success was undeterminable. During a median follow-up time of 8 months after latest RFA, 100 patients (76%) stayed free from recurrence. We observed no difference in procedural or long-term success between patients with and without AIC. When excluding patients with fascicular ventricular tachycardia (VT), a significantly higher proportion of patients with AIC had VA originating from the left ventricle (p = 0.027). Patients with AIC had a significant improvement of ejection fraction after RFA (p < 0.001). Totally 89 of 99 patients (90%) who returned the questionnaire reported symptomatic benefit a median of 64 months after their latest procedure. CONCLUSIONS: RFA is effective for treating idiopathic VA with and without AIC, with high rates of long-term freedom from VA and symptomatic relief. We found more patients with AIC had left ventricle VA.

Incidence of Atrial Fibrillation After Radiofrequency Catheter Ablation for Atrial Tachycardia in Congenital Heart Disease.

BACKGROUND: Atrial tachycardia (AT) and atrial fibrillation (AF) coexist in 30% of congenital heart disease (CHD) patients. Successful atrial tachycardia catheter ablation (ATCA) might prevent AF. Data on new-onset AF after ATCA in CHD is scarce. OBJECTIVES: This study aimed to evaluate the incidence of new-onset AF after ATCA and to assess clinical characteristics associated with new-onset AF after ATCA in CHD. METHODS: CHD patients referred for ATCA to 3 European centers were included. New occurrence of AF was defined as electrocardiographic documentation of AF after any ATCA procedure in patients without history of AF. RESULTS: In 277 CHD patients (median age 37 years [Q1, Q3: 23, 49 years], 58% men, 59 [21%] simple, 111 [40%] moderate, and 107 [39%] complex CHD), AF occurred in 25 patients (9%) a median of 8 months (Q1, Q3: 4, 27 months) after ATCA. New-onset AF was persistent in the majority of the patients (17 of 25 [63%]). Patients with new-onset AF were older (44 years [Q1, Q3: 29, 55 years] vs 36 years [Q1, Q3: 23, 49 years]; P = 0.009) and more frequently had simple CHD (13 of 25 [52%] vs 46 of 252 [18%], respectively; P < 0.0001). Acute ATCA success rates were similar in patients with and without AF (52% vs 48%; P = 0.429). Simple CHD was an independent predictor of new-onset AF during follow-up. CONCLUSIONS: In our large cohort of patients with congenital heart disease, new-onset AF after ablation for AT occurred in only 9% of the patients. AF occurred without AT recurrence and was persistent in the majority of patients.

Multisize Electrode Field-of-View: Validation by High Resolution Gadolinium-Enhanced Cardiac Magnetic Resonance.

BACKGROUND: Voltage mapping to detect ventricular scar is important for guiding catheter ablation, but the field-of-view of unipolar, bipolar, conventional, and microelectrodes as it relates to the extent of viable myocardium (VM) is not well defined. OBJECTIVES: The purpose of this study was to evaluate electroanatomic voltage-mapping (EAVM) with different-size electrodes for identifying VM, validated against high-resolution ex-vivo cardiac magnetic resonance (HR-LGE-CMR). METHODS: A total of 9 swine with early-reperfusion myocardial infarction were mapped with the QDOT microcatheter. HR-LGE-CMR (0.3-mm slices) were merged with EAVM. At each EAVM point, the underlying VM in multisize transmural cylinders and spheres was quantified from ex vivo CMR and related to unipolar and bipolar voltages recorded from conventional and microelectrodes. RESULTS: In each swine, 220 mapping points (Q1, Q3: 216, 260 mapping points) were collected. Infarcts were heterogeneous and nontransmural. Unipolar and bipolar voltage increased with VM volumes from >175 mm3 up to >525 mm3 (equivalent to a 5-mm radius cylinder with height >6.69 mm). VM volumes in subendocardial cylinders with 1- or 3-mm depth correlated poorly with all voltages. Unipolar voltages recorded with conventional and microelectrodes were similar (difference 0.17 ± 2.66 mV) and correlated best to VM within a sphere of radius 10 and 8 mm, respectively. Distance-weighting did not improve the correlation. CONCLUSIONS: Voltage increases with transmural volume of VM but correlates poorly with small amounts of VM, which limits EAVM in defining heterogeneous scar. Microelectrodes cannot distinguish thin from thick areas of subendocardial VM. The field-of-view for unipolar recordings for microelectrodes and conventional electrodes appears to be 8 to 10 mm, respectively, and unexpectedly similar.

Serum and lymph pharmacokinetics of nilotinib delivered by yeast glucan particles per os.

Nilotinib is a selective tyrosine-kinase inhibitor approved for the treatment of chronic myeloid leukemia. It is poorly soluble in aqueous media and has a low oral bioavailability. Nilotinib encapsulation into yeast glucan particles (GPs) was investigated in this work as a means of increasing bioavailability. The amorphization of nilotinib in GPs resulted in an increased dissolution rate, which was confirmed by in vitro experiments using biorelevant dissolution media. Simultaneously, GPs containing nilotinib were effectively taken up by macrophages, which was quantified in vitro on cell cultures. The overall oral bioavailability in a rat model was approximately 39 % for nilotinib delivered in a reference formulation (Tasigna) and was almost doubled when delivered in GPs. The contribution of glucan particles to the lymphatic transport of nilotinib was quantified. When delivered by GPs, cumulative nilotinib absorption via the lymphatic system increased by a factor of 10.8 compared to the reference, but still represented arelative bioavailability of only 1.12 %. The cumulative uptake of GPs in the lymph was found to be 0.54 mg after a single dose of 50 mg. Yeast glucan particles can therefore serve as a drug delivery vehicle with a dual function: dissolution rate enhancement by amorphization, and, to asmaller extent, lymphatic delivery due to macrophage uptake.

Long-term outcome of ablative therapy of post-operative atrial tachyarrhythmias in patients with tetralogy of Fallot: a European multi-centre study.

AIM: Post-operative atrial tachyarrhythmias (AT) in patients with tetralogy of Fallot (ToF) are associated with congestive heart failure, stroke, and cardiac death. Effective treatment is therefore essential. The aim of the study is to evaluate long-term outcome of ablative therapy of AT in ToF patients and to study characteristics of AT recurrences. METHODS AND RESULTS: Tetralogy of Fallot patients (N = 38, age 43 ± 12 years) referred for ablation of post-operative AT, appearing 26 ± 10 years after complete repair, were studied. Electro-anatomical/entrainment mapping was performed prior to ablation. Successful ablation was defined as (i) achievement of bi-directional conduction block for isthmus-dependent atrial flutter (IDAF), (ii) termination during ablation for intra-atrial reentrant tachycardia (IART) and focal atrial tachycardia (FAT). Fifty-two AT were ablated, including 37 IDAF [cycle length (CL) 294 ± 70 ms], 11 IART (CL 295 ± 46 ms), and 4 FAT (CL 371 ± 93 ms). Ablation was successful in 98%. Fifty-one of 52 AT involved the cavo-tricuspid isthmus and/or the area between scar tissue related to prior atriotomy incisions and the inferior caval vein. Multiple AT developed in 11 patients, with different mechanisms in 9. After 45 ± 24 months, 32 patients were in sinus rhythm; 5 used anti-arrhythmic drugs. CONCLUSION: Ablative therapy of AT in ToF patients is an effective curative treatment modality with a high procedural success rate. Sinus rhythm during long-term follow-up was obtained in the majority of patients. Fifty-one of 52 AT originated from sites related to surgical incisions created at complete repair, suggesting that extending the atriotomy incision towards the inferior caval vein during cardiac surgery combined with surgical ablation of the cavo-tricuspid isthmus will be effective in preventing development of AT.

Recurrent atrial arrhythmia in a randomised controlled trial comparing contact force-guided and contact force-blinded ablation for typical atrial flutter.

BACKGROUND: Contact force (CF)-guided catheter ablation (CA) is a novel technology developed to improve efficacy and reduce complications. In a randomised controlled trial (RCT), we previously documented that after 3 months, rate of persistent conduction block was similar with and without using CF while performing CA for typical atrial flutter (AFL). Clinical effect of CF on recurrent arrhythmia is unknown. Our objective is to study recurrent atrial arrhythmia during 12-month follow-up in a RCT investigating whether CF-guided CA for typical AFL is superior to CF-blinded CA. METHODS: Patients were randomised 1:1 to CA guided by CF (intervention group) or blinded to CF (control group). After 12 months, patients attended clinical check-up preceded by a 5-day ambulatory Holter monitor recording. Primary outcome was any recurrent atrial arrhythmia ≥ 30 s within 12 months and documented in 12-lead ECG or Holter monitor recording. RESULTS: We included 156 patients, four patients withdrew consent and two died during follow-up. Thus, 150 patients were included in final analysis. Recurrent arrhythmia was detected in 36 of 77 (47%) patients in the intervention group, and 32 of 73 patients (44%) in the control group (p = 0.51). Atrial fibrillation was detected in 23 (30%) and 29 (40%) patients in the intervention and control groups respectively. AFL was detected in 11 (14%) and 5 (7%) patients in the intervention and control groups respectively. CONCLUSIONS: Contact force-guided ablation for typical atrial flutter does not reduce recurrent atrial arrhythmia after 12-month follow-up as compared with ablation blinded for contact force.

Catheter ablation of arrhythmias in ebstein's anomaly: a multicenter study.

INTRODUCTION: In patients with Ebstein's anomaly (EA) arrhythmias are frequently encountered. Although most arrhythmias can be targeted with catheter ablation, specific issues render the procedure more challenging in EA. This study examines the mechanisms of the different arrhythmias related to EA and the outcome after catheter ablation. METHODS AND RESULTS: Clinical and procedural data of catheter ablation in patients with EA in 4 European centers were analyzed. In 32 patients (mean age 24 ± 15 years), 34 accessory pathways (APs), 8 intra-atrial reentry tachycardias (IART), 5 cavotricuspid isthmus-dependent atrial flutter (CTI-AFL), 2 focal atrial tachycardias, and 1 atrioventricular nodal reentry tachycardia were ablated. In 11 patients (34%), multiple ablation targets were present. Eighteen patients (56%) required multiple procedures either for repeat ablation of the same arrhythmia (n = 12), ablation of a different arrhythmia (n = 4), or both re-ablation of the same and of a different arrhythmia (n = 2). Procedural success rate after first ablation was 80% for APs and CTI-AFL ablation, and 100% for IART ablation. Redo procedures were necessary in 40% of the patients after ablation of an APs, and in 60% after CTI-AFL ablation, but in none of the patient with IART ablation. CONCLUSION: Most arrhythmias related to EA are amenable to catheter ablation. However, ablation procedures are challenging and the need for repeat procedure is particularly high, because some patients have multiple ablation targets and because of technical issues in relation with the dysplastic tricuspid annulus. In addition, several patients develop other arrhythmia mechanisms following ablation.

Radiofrequency catheter ablation in 246 children with supraventricular tachyarrhythmia.

INTRODUCTION: Radiofrequency catheter ablation (RFA) is the treatment of choice for a variety of cardiac arrhythmias in adults. RFA is considered effective and is associated with few complications. We aimed to review the characteristics and outcomes of invasive electrophysiological study (EPS) and RFA in children with supraventricular tachyarrhythmia. METHODS: Consecutive patients younger than 16 years of age undergoing EPS and possible RFA from January 2009 to September 2018 at Aarhus University Hospital (uptake three million people) were reviewed retrospectively. Procedural and outcome data were collected from patient charts and from the Danish Ablation Database. Numbers (%) or median (range) are reported. RESULTS: A total of 304 patients (148 girls) underwent EPS (352 procedures). RFA was performed in 246 patients (279 procedures), aged 13 (1-15) years and weighing 46 (6-99) kg. Treatment success was achieved in 195 (79%) of the initial procedures. Using more than one procedure, 227 (92%) patients were free from arrhythmia after 89 (26-143) months of follow-up. The procedure time was 60 (22-222) min. and ablation time 2 (1-23) min. Major complications occurred in two cases. One patient developed transient superior vena cava syndrome and one patient developed an atrioventricular block requiring pacemaker implantation. CONCLUSIONS: RFA may be performed in children with a high success rate and a low but not negligible risk of complications. FUNDING: none. TRIAL REGISTRATION: Approval was obtained from the Danish Data Protection Agency (1-16-02-430-13).

Contemporary Patients With Congenital Heart Disease: Uniform Atrial Tachycardia Substrates Allow for Clear Ablation Endpoints With Improved Long-Term Outcome.

[Figure: see text].

Vancomycin-releasing cross-linked collagen sponges as wound dressings.

The study presents a novel vancomycin-releasing collagen wound dressing derived from Cyprinus carpio collagen type I cross-linked with carbodiimide which retarded the degradation rate and increased the stability of the sponge. Following lyophilization, the dressings were subjected to gamma sterilization. The structure was evaluated via scanning electron microscopy images, micro-computed tomography, and infrared spectrometry. The structural stability and vancomycin release properties were evaluated in phosphate buffered saline. Microbiological testing and a rat model of a wound infected with methicillin-resistant Staphylococcus aureus (MRSA) were then employed to test the efficacy of the treatment of the infected wound. Following an initial mass loss due to the release of vancomycin, the sponges remained stable. After 7 days of exposure in phosphate buffered saline (37°C), 60% of the material remained with a preserved collagen secondary structure together with a high degree of open porosity (over 80%). The analysis of the release of vancomycin revealed homogeneous distribution of the antibiotic both across and between the sponges. The release of vancomycin was retarded as proved by in vitro testing and further confirmed by the animal model from which measurable concentrations were observed in blood samples 24 hours after the subcutaneous implantation of the sponge, which was more than observed following intraperitoneal administration. The sponge was also highly effective in terms of reducing the number of colony-forming units in biopsies extracted from the infected wounds 4 days following the inoculation of the wounds with the MRSA solution. The presented sponges have ideal properties to serve as wound dressing for prevention of surgical site infection or treatment of already infected wounds.

Validity of cycloheximide chylomicron flow blocking method for the evaluation of lymphatic transport of drugs.

BACKGROUND AND PURPOSE: Lymphatic transport of drugs after oral administration is an important mechanism for absorption of highly lipophilic compounds. Direct measurement in lymph duct cannulated animals is the gold standard method, but non-invasive cycloheximide chylomicron flow blocking method has gained popularity recently. However, concerns about its reliability have been raised. The aim of this work was to investigate the validity of cycloheximide chylomicron flow blocking method for the evaluation of lymphatic transport using model compounds with high to very high lipophilicity, that is, abiraterone and cinacalcet. EXPERIMENTAL APPROACH: Series of pharmacokinetic studies were conducted with abiraterone acetate and cinacalcet hydrochloride after enteral/intravenous administration to intact, lymph duct cannulated and/or cycloheximide pre-treated rats. KEY RESULTS: Mean total absolute oral bioavailability of abiraterone and cinacalcet was 7.0% and 28.7%, respectively. There was a large and significant overestimation of the lymphatic transport extent by the cycloheximide method. Mean relative lymphatic bioavailability of abiraterone and cinacalcet in cycloheximide method was 28-fold and 3-fold higher than in cannulation method, respectively. CONCLUSION AND IMPLICATIONS: Cycloheximide chylomicron flow blocking method did not provide reliable results on lymphatic absorption and substantially overestimated lymphatic transport for both molecules, that is, abiraterone and cinacalcet. This non-invasive method should not be used for the assessment of lymphatic transport and previously obtained data should be critically revised.