Introduction Dabigatran Boehringer Ingelheim Ingelheim Germa
Dabigatran (Boehringer Ingelheim, Ingelheim, Germany) is a direct thrombin inhibitor, which can be orally administered, and is used to decrease the risk of ischemic stroke in patients with non-valvular atrial fibrillation (NVAF). In early phase studies of dabigatran in healthy men, cyclin dependent kinase inhibitor dabigatran concentrations were found to rapidly increase and reach a peak value within 1.5–3h after oral administration of the drug [1–4]. However, the timing of peak plasma dabigatran concentration in daily clinical practice is not fully understood. When dabigatran was first approved for use, monitoring of clotting time was considered unnecessary; however, cases of large hemorrhage with a markedly prolonged clotting time have been observed. Additionally, in certain situations, monitoring of plasma concentrations and/or the anticoagulant action of dabigatran is required as risk screening for effects of excess dabigatran [5–7]. Therefore, it is recommended that activated partial thromboplastin time (aPTT) be used as a parameter for monitoring anticoagulant activity in dabigatran-treated patients [1,8,9]. The relationship between aPTT and dabigatran therapy has recently gained a lot of attention; however, there are limited data in Japanese patients [10–14].
Material and methods
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Introduction Catheter ablation of atrial fibrillation (AF) has been rapidly popularized by the appearance of three-dimensional (3D) mapping systems. Wide encircling isolation of the entire pulmonary vein (PV) antrum from the left atrial side provides the ability to eliminate AF trigger as well as treat the AF substrate. Complete isolation of the entire circle is considered the optimal electrophysiological end point. However, given the complex and highly variable individual 3D PV antrum anatomy, achievement of continuity and transmurality along the entire encircling ablation line is challenging. Hence, high-resolution images from magnetic resonance (MR) or computed tomographic (CT) imaging integrated with 3D mapping systems represent a highly desirable technique to maximize the efficacy and minimize the risks of AF ablation procedures [1–3]. Pulmonary venous and left atrial (PV–LA) anatomy is usually assessed with contrast-enhanced CT, because the non-contrast-enhanced MR imaging approach has not been well established . Recently, examination using a 3D balanced steady-state free precession (b-SSFP) sequence has been reported (3D-B method) [5,6]. b-SSFP imaging techniques have progressed for evaluating the thoracic vasculature, including the coronary arteries and thoracic aorta, because of their inherent high signal-to-noise and contrast-to-noise ratios [7–9]. However, a PV signal intensity defect frequently occurs with practical use of the 3D-B method . Actually, in cases of patients with renal failure, we must attempt the AF ablation and complete the procedure safely with compromising the image quality. The precise anatomical information of the LA antrum region and anterior ridge between the left atrial appendage (LAA) and left superior PV (LSPV) is necessary to achieve continuity of the ablation line. We assessed the feasibility of an MR imaging acquisition and processing protocol, a b-SSFP sequence without a contrast agent (2D-B method), to depict the accurate PV–LA anatomy for AF ablation.
Material and methods
Conflict of interest
Introduction Syncope is a syndrome in which a relatively short period of temporary and self-limited loss of consciousness is caused by a transient diminution of blood flow to the brain. The prevalence of syncope in the general population is reported to vary from 15% to 23% . Vasovagal syncope is a transient loss of consciousness caused by systemic arterial hypotension resulting from reflex vasodilatation and/or bradycardia. It is the most common cause of syncope in the general population and is responsible for one-fifth of all syncope episodes .