Safe procedures despite ultra low radiation doses during catheter ablations of atrial and ventricular arrhythmias—A multicenter experience

Introduction: Despite the development of non-fluoroscopic catheter visualization options, fluoroscopy is still used in most ablation procedures. The aim of this multicenter study was to evaluate the safety and efficacy of a new ultra-low dose radiation protocol for EP procedures in a large number of patients. Methods and results: A total of 3462 consecutive patients (male 1926 (55.6%), age 64.4 ± 14.0 years, BMI 26.65 ± 4.70) undergoing radiofrequency ablation (left atrial (n = 2316 [66.9%], right atrial (n = 675 [19.5%], or ventricular (n = 471 [13.6%]) in three German centers were included in the analysis. Procedures were performed using a new ultra-low dose protocol operating at 8nGy for fluoroscopy and 36nGy for cine-loops. Additionally a very low framerate (2-3FPS) was used. Using the new protocol very low Air kerma-area product (KAP) values were achieved for left atrial ablations (104.25 ± 84.22 μGym2 ), right atrial ablations (70.98 ± 94.79 μGym2 ) and ablations for ventricular tachycardias or PVCs (78.62 ± 66.59 μGym2 ). Acute procedural success was achieved in 3289/3388 (97.1%) while the rate of major complications was very low compared to previously published studies not using low dose settings (n = 20, 0.6%). Conclusion: The ultra-low dose, low framerate protocol leads to very low radiation doses for all EP procedures while neither procedural time, fluoroscopy time nor success or complication rates were compromised. When compared to current real-world Air KAP data the new ultra-low dose fluoroscopy protocol reduces radiation exposure by more than 90%

Automated segmentation of the atrial region and fossa ovalis towards computer-aided planning of inter-atrial wall interventions

Image-fusion strategies have been applied to improve inter-atrial septal (IAS) wall minimally-invasive interventions. Hereto, several landmarks are initially identified on richly-detailed datasets throughout the planning stage and then combined with intra-operative images, enhancing the relevant structures and easing the procedure. Nevertheless, such planning is still performed manually, which is time-consuming and not necessarily reproducible, hampering its regular application. In this article, we present a novel automatic strategy to segment the atrial region (left/right atrium and aortic tract) and the fossa ovalis (FO).Fundacão para a Ciência e a Tecnologia (FCT), in Portugal, and the European Social Found, European Union, for funding support through the “Programa Operacional Capital Humano” (POCH) in the scope of the PhD grants SFRH/BD/95438/2013 (P. Morais) and SFRH/BD/93443/2013 (S. Queirós). This work was funded by projects NORTE-01-0145-FEDER-000013, NORTE-01-0145-FEDER-000022 and NORTE-01-0145-FEDER-024300, supported by Northern Portugal Regional Operational Programme (Norte2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER), and also been funded by FEDER funds, through Competitiveness Factors Operational Programme (COMPETE), and by national funds, through the FCT, under the scope of the project POCI-01-0145-FEDER-007038info:eu-repo/semantics/publishedVersio

A competitive strategy for atrial and aortic tract segmentation based on deformable models

Multiple strategies have previously been described for atrial region (i.e. atrial bodies and aortic tract) segmentation. Although these techniques have proven their accuracy, inadequate results in the mid atrial walls are common, restricting their application for specific cardiac interventions. In this work, we introduce a novel competitive strategy to perform atrial region segmentation with correct delineation of the thin mid walls, and integrated it into the B-spline Explicit Active Surfaces framework. A double stage segmentation process is used, which starts with a fast contour growing followed by a refinement stage with local descriptors. Independent functions are used to define each region, being afterward combined to compete for the optimal boundary. The competition locally constrains the surface evolution, prevents overlaps and allows refinement to the walls. Three different scenarios were used to demonstrate the advantages of the proposed approach, through the evaluation of its segmentation accuracy, and its performance for heterogeneous mid walls. Both computed tomography and magnetic resonance imaging datasets were used, presenting results similar to the state-of-the-art methods for both atria and aorta. The competitive strategy showed its superior performance with statistically significant differences against the traditional free-evolution approach in cases with bad image quality or missed atrial/aortic walls. Moreover, only the competitive approach was able to accurately segment the atrial/aortic wall. Overall, the proposed strategy showed to be suitable for atrial region segmentation with a correct segmentation of the mid thin walls, demonstrating its added value with respect to the traditional techniques.The authors acknowledge Fundacao para a Ciencia e a Tecnologia (FCT), in Portugal, and the European Social Found, European Union, for funding support through the "Programa Operacional Capital Humano" (POCH) in the scope of the PhD grants SFRH/BD/95438/2013 (P. Morais) and SFRH/BD/93443/2013 (S. Queiros).Authors gratefully acknowledge the funding of projects NORTE-01-0145-FEDER-000013 and NORTE-01-0145-FEDER-000022, co-financed by "Programa Operacional Regional do Norte" (NORTE2020), through "Fundo Europeu de Desenvolvimento Regional" (FEDER).info:eu-repo/semantics/publishedVersio

Atrial Fibrillation Mechanisms and Implications for Catheter Ablation

AF is a heterogeneous rhythm disorder that is related to a wide spectrum of etiologies and has broad clinical presentations. Mechanisms underlying AF are complex and remain incompletely understood despite extensive research. They associate interactions between triggers, substrate and modulators including ionic and anatomic remodeling, genetic predisposition and neuro-humoral contributors. The pulmonary veins play a key role in the pathogenesis of AF and their isolation is associated to high rates of AF freedom in patients with paroxysmal AF. However, ablation of persistent AF remains less effective, mainly limited by the difficulty to identify the sources sustaining AF. Many theories were advanced to explain the perpetuation of this form of AF, ranging from a single localized focal and reentrant source to diffuse bi-atrial multiple wavelets. Translating these mechanisms to the clinical practice remains challenging and limited by the spatio-temporal resolution of the mapping techniques. AF is driven by focal or reentrant activities that are initially clustered in a relatively limited atrial surface then disseminate everywhere in both atria. Evidence for structural remodeling, mainly represented by atrial fibrosis suggests that reentrant activities using anatomical substrate are the key mechanism sustaining AF. These reentries can be endocardial, epicardial, and intramural which makes them less accessible for mapping and for ablation. Subsequently, early interventions before irreversible remodeling are of major importance. Circumferential pulmonary vein isolation remains the cornerstone of the treatment of AF, regardless of the AF form and of the AF duration. No ablation strategy consistently demonstrated superiority to pulmonary vein isolation in preventing long term recurrences of atrial arrhythmias. Further research that allows accurate identification of the mechanisms underlying AF and efficient ablation should improve the results of PsAF ablation

Mapping and Ablation of Idiopathic Ventricular Fibrillation

Idiopathic ventricular fibrillation (IVF) is the main cause of unexplained sudden cardiac death, particularly in young patients under the age of 35. IVF is a diagnosis of exclusion in patients who have survived a VF episode without any identifiable structural or metabolic causes despite extensive diagnostic testing. Genetic testing allows identification of a likely causative mutation in up to 27% of unexplained sudden deaths in children and young adults. In the majority of cases, VF is triggered by PVCs that originate from the Purkinje network. Ablation of VF triggers in this setting is associated with high rates of acute success and long-term freedom from VF recurrence. Recent studies demonstrate that a significant subset of IVF defined by negative comprehensive investigations, demonstrate in fact subclinical structural alterations. These localized myocardial alterations are identified by high density electrogram mapping, are of small size and are mainly located in the epicardium. As reentrant VF drivers are often colocated with regions of abnormal electrograms, this localized substrate can be shown to be mechanistically linked with VF. Such areas may represent an important target for ablation

Early Repolarization Syndrome: Diagnostic and Therapeutic Approach

An early repolarization pattern can be observed in 1% up to 13% of the overall population. Whereas, this pattern was associated with a benign outcome for many years, several more recent studies demonstrated an association between early repolarization and sudden cardiac death, so-called early repolarization syndrome. In early repolarization syndrome patients, current imbalances between epi- and endo-cardial layers result in dispersion of de- and repolarization. As a consequence, J waves or ST segment elevations can be observed on these patients' surface ECGs as manifestations of those current imbalances. Whereas, an early repolarization pattern is relatively frequently found on surface ECGs in the overall population, the majority of individuals presenting with an early repolarization pattern will remain asymptomatic and the isolated presence of an early repolarization pattern does not require further intervention. The mismatch between frequently found early repolarization patterns in the overall population, low incidences of sudden cardiac deaths related to early repolarization syndrome, but fatal, grave consequences in affected patients remains a clinical challenge. More precise tools for risk stratification and identification of this minority of patients, who will experience events, remain a clinical need. This review summarizes the epidemiologic, pathophysiologic and diagnostic background and presents therapeutic options of early repolarization syndrome

Die simultane Inkubation mit exogenen und endogenen Toll-like Rezeptor-Liganden bedingt eine Aggravierung des Schädigungsmusters

Die angeborene und die adaptive Immunität bilden die beiden grundlegenden Mechanismen der menschlichen Immunabwehr. Sie umfassen verschiedene Komponenten, die der Unterscheidung zwischen körpereigenen und körperfremden Strukturen dienen. Ein wichtiges Element der angeborenen Immunität ist das TLR-System. Die TLR erkennen einerseits exogene molekulare Strukturmotive, die spezifischer Bestandteil bakterieller, viraler oder parasitärer Pathogene sind. Andererseits erkennen die TLR endogene Substanzen, die z.B. im Rahmen gewebsschädigender Prozesse freigesetzt werden. Dazu zählt insbesondere der I/R-Schaden, der unvermeidbar im Zusammenhang mit Nierentransplantationen auftritt. Aktivierte TLR lösen eine intrazelluläre Signalkaskade aus, die die Expression eines proinflammatorischen Zytokin- und Chemokinprofils bewirkt. Im Rahmen dieser Arbeit wurden eine podozytäre und eine IMCD-Zelllinie, die ortsständige renale Zellen, sowie eine WEHI-Zelllinie, die infiltrierende Makrophagen repräsentiert, separat und kombiniert mit exogenen und endogenen TLR-Liganden stimuliert. Nach der Inkubation wurde das Ausmaß der resultierenden Expression von TNFα und CCL2, Repräsentanten der proinflammatorischen Zytokine und Chemokine, analysiert. Dazu wurde einerseits die Expression von TNFα und CCL2 auf mRNA-Ebene mittels RT qPCR quantifiziert. Andererseits wurde die letztendlich der mRNA-Synthese nachfolgende Proteinexpression von TNFα und CCL2 mittels ELISA und Western Blot Analyse dargestellt. Für beide untersuchten renalen Zelllinien als auch für die infiltrierende Zelllinie konnte gezeigt werden, dass die kombinierte Inkubation mit exogen/endogen TLR-Liganden im Vergleich zu einer separaten Inkubation mit exogenen oder endogenen TLR-Liganden zu einer Vervielfachung der proinflammatorischen Zytokin- und Chemokinantwort führt. Durch Gen-Knockdown mittels TLR4-spezifischer siRNA konnte bestätigt werden, dass die aus kombinierter Inkubation erfolgende proinflammatorische Reaktion spezifisch über den TLR-Signalweg erfolgt. Patienten, die nach Nierentransplantation an Harnwegsinfekten erkranken, sind häufiger von Abstoßungsreaktionen sowie auch einer Verschlechterung der Langzeittransplantatfunktion betroffen. Die Resultate dieser Arbeit könnten darauf hinweisen, dass ein simultan exogen und endogen aktiviertes TLR-System hierbei möglicherweise von Bedeutung sein kann. Die pharmakologische Blockade des TLR-Systems könnte dazu genutzt werden, I/R Schaden sowie Inflammation im Rahmen der Nierentransplantation zu reduzieren

Cryo-Balloon Catheter Tracking in Atrial Fibrillation Ablation Procedures

Abstract. Radio-frequency (RF) catheter ablation has become the standard treatment of atrial fibrillation if pharmacotherapy fails. As an alternative to traditional RF standard ablation catheters, single-shot devices have received more and more interest. One group of these devices are cryo-balloon catheters. Such catheters are designed to electrically isolate a pulmonary vein (PV) with only a few applications, ideally only one. Whereas standard radio-frequency ablation catheters operate point by point, cryo-balloon devices need to be positioned antrally to the pulmonary vein ostium before freezing. If a good seal can be achieved far enough outside of the pulmonary veins, the cryo-balloon is an effective and safe ablation device. The catheters are inserted through a transseptal sheath and are inflated using liquid nitrogen. Single-shot devices, when used successfully, promise a reduction of procedure time and X-ray exposure. Single-shot devices based on ablation energies other than RF, may not carry electrodes or electromagnetic sensors. This makes it difficult to visualize them using standard EP mapping systems. As a result, fluoroscopic imaging is needed. Unfortunately, the inflated balloon may be difficult to see under X-ray. To improve this situation, we propose a new method that tracks and enhances the visualization of a cryo-balloon catheter under fluoroscopic imaging. The method involves a 2-D template of the cryo-balloon that is manually initialized and then tracks the balloon device during live X-ray imaging. To improve visualization, a 2-D ellipse is overlaid onto the fluoroscopic imaging to highlight the position of the balloon catheter. The tracking error was calculated as the distance between the tracked catheter template and the manually segmented catheter. Our method achieved 2-D tracking error of 0.60 mm±0.32 mm.