Catheter ablation of atrial fibrillation guided by electrogram fractionation and dominant frequency analysis

Catheter ablation is an established therapeutic option for certain patients with atrial fibrillation (AF), but the reported success rates of anatomically oriented ablation techniques are low compared with those for other ablation indications, particularly for persistent AF. Electrophysiologically oriented ablation techniques have emerged over the last decade that aim at modifying the arrhythmogenic substrate to the extent that it cannot maintain fibrillatory activity. Electrogram-guided ablation procedures are the most common substrate-targeted ablation approaches and can be broadly divided into procedures that target atrial sites with particular electrogram characteristics in either the time domain (complex fractionated electrograms) or frequency components in the frequency domain (dominant frequencies). The concept of electrogram-based catheter ablation of AF by identifying complex fractionated electrograms and dominant frequency sites is valid only if these sites are temporally stable. © 2011 Expert Reviews Ltd

Two and Three-Dimensional Quantitative Coronary Angiography

Following the development of the first automated methods in the 1980s, quantitative coronary angiography (QCA) has undergone substantial evolution from simplistic computer-assisted methods of visual interpretation of coronary angiograms to recently introduced three-dimensional reconstruction and quantitative analysis algorithms. The ability of QCA to provide objective dimensional assessment of coronary lesions is still useful and has led to its widespread application in both scientific research and clinical practice. Most of the systems available nowadays are based on vessel edge detection algorithms to designate the arterial lumen on conventional two-dimensional coronary angiograms. Three generations of these systems have been developed with improved accuracy and precision of obtained measurements. Techniques for reconstruction of the two-dimensional coronary angiogram in space have allowed the implementation of three-dimensional QCA. This new technology may solve many of the limitations inherent in two-dimensional QCA and provide stenosis assessment capabilities not available with two-dimensional imaging. © 2009 Elsevier Inc. All rights reserved

Vascular wall shear stress in clinical practice

Wall shear stress is a fluid dynamic quantity that is gradually emerging as a potentially important factor of coronary atherosclerosis. Methods, therefore, of estimation of shear stress in the arterial system are of clinical relevance. The purpose of this review is to define wall shear stress, review the various methods that have been used for its assessment in human circulation, and examine the methodological limitations and applicability of each method in clinical practice. © 2007 Bentham Science Publishers Ltd

Patient radiation doses in interventional cardiology procedures

Interventional cardiology procedures result in substantial patient radiation doses due to prolonged fluoroscopy time and radiographic exposure. The procedures that are most frequently performed are coronary angiography, percutaneous coronary interventions, diagnostic electrophysiology studies and radiofrequency catheter ablation. Patient radiation dose in these procedures can be assessed either by measurements on a series of patients in real clinical practice or measurements using patient-equivalent phantoms. In this article we review the derived doses at non-pediatric patients from 72 relevant studies published during the last 22 years in international scientific literature. Published results indicate that patient radiation doses vary widely among the different interventional cardiology procedures but also among equivalent studies. Discrepancies of the derived results are patient-, procedure-, physician-, and fluoroscopic equipment-related. Nevertheless, interventional cardiology procedures can subject patients to considerable radiation doses. Efforts to minimize patient exposure should always be undertaken. © 2009 Bentham Science Publishers Ltd

Flow patterns at stented coronary bifurcations: Computational fluid dynamics analysis

Background: The ideal bifurcation stenting technique is not established, and data on the hemodynamic characteristics at stented bifurcations are limited. Methods and Results: We used computational fluid dynamics analysis to assess hemodynamic parameters known affect the risk of restenosis and thrombosis at coronary bifurcations after the use of various single- and double-stenting techniques. We assessed the distributions and surface integrals of the time averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (r). Single main branch stenting without side branch balloon angioplasty or stenting provided the most favorable hemodynamic results (integrated values of TAWSS=4.13·10-4 N, OSI=7. 52·10-6 m2, r=5.57·10 -4 m2/Pa) with bifurcational area subjected to OSI values >0.25, >0.35, and >0.45 calculated as 0.36 mm2,0.04 mm 2, and 0 mm2, respectively. Extended bifurcation areas subjected to these OSI values were seen after T-stenting: 0.61 mm2, 0.18 mm 2, and 0.02 mm2, respectively. Among the considered double-stenting techniques, crush stenting (integrated values of TAWSS=1.18·104 N, OSI=7.75·10-6 m 2, r=6.16·10-4 m2/Pa) gave the most favorable results compared with T-stenting (TAWSS=0.78·10 -4 N, OSI=10.40·10-6 m2, r=6.87·10-4μm2/Pa) or the culotte technique (TAWSS=1.30· 10-4 N,OSI=9.87·10-6 m2, r=8.78·10-4 m2/Pa). Conclusions: In the studied models of computer simulations, stenting of the main branch with our without balloon angioplasty of the side branch offers hemodynamic advantages over double stenting. When double stenting is considered, the crush technique with the use of a thin-strut stent may result in improved immediate hemodynamics compared with culotte or T-stenting. © 2012 American Heart Association, Inc

Radiation exposure of the operator during cardiac catheter ablation procedures

Radiation exposure of the operator during cardiac catheter ablation procedures was assessed for an experienced cardiologist adopting various measures of radiation protection and utilised electroanatomic navigation. Chip thermoluminescent dosemeters were placed at the eyes, chest, wrists and legs of the operator. The ranges of fluoroscopy time and air kerma area product values associated with cardiac ablation procedures were wide (6.3-48.3 min and 1.7-80.3 Gy cm. 2, respectively). The measured median radiation doses per procedure for each monitored position were 23.6 and 21.3 μSv to the left and right wrists, respectively, 25.3 and 30.4 μSv to the left and right legs, respectively. The doses to the eyes were below the minimum detectable dose of 9 μSv. The estimated median effective dose was 22.5 μSv. Considering the actual workload of the operator, the calculated annual doses to the hands, legs and eyes, as well as the annual effective dose, were all below the corresponding limits. The findings of this study indicate that cardiac ablation procedures performed at a modern laboratory do not impose a high radiation hazard to the operator when radiation protection measures are routinely adopted. © The Author 2012. Published by Oxford University Press. All rights reserved

Antiendothelial cell antibodies in patients with coronary artery ectasia

BACKGROUND: The mechanisms involved in the pathogenesis of coronary artery ectasia (CAE) have not been elucidated. Circulating antiendothelial cell antibodies (AECA) are often detectable in systemic vasculitis and have been implicated in the pathogenesis of endothelial injury. Their prevalence in CAE is not known. METHODS AND Results: Out of 475 consecutive patients subjected to coronary angiography, 27 patients were diagnosed with CAE. Thirty patients matched for age, body mass index, sex, and coronary artery disease prevalence, served as controls. Serum AECA of IgG, IgM, and IgA isotypes were detected using a cell-based enzyme-linked immunosorbent assay (ELISA). Antinuclear antibodies (ANA) and antineutrophil cytoplasmic antibodies (ANCA) were detected using indirect immunofluorescence. IgG and IgM anticardiolipin antibodies (aCL) were detected using commercial ELISA. The prevalence of ANA and ANCA was similar in CAE patients and controls (33.3 vs. 43.3%, and 3.3 vs. 7.4%, respectively). There was no significant difference in IgG or IgM aCL reactivity between patients and controls. Both CAE patients and controls were negative for IgG AECA. The frequency of IgM AECA positivity was similar in CAE patients and controls. The prevalence of AECA of the IgA isotype was significantly higher in CAE patients (37.0 vs. 10%, P<0.05). Conclusion: There is increased prevalence of circulating AECA of the IgA isotype in patients with CAE. This provides evidence for a role of autoimmunity in the pathogenesis of certain cases of CAE. Copyright © 2010 Lippincott Williams & Wilkins