Michael Derntl

Medical University of Vienna, Wien, Vienna, Austria

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Publications (12)15.64 Total impact

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    ABSTRACT: Two female patients undergoing left atrial radiofrequency catheter ablation developed Tako-tsubo cardiomyopathy. This reversible form of left ventricular dysfunction is known to occur under conditions associated with marked sympathetic nervous activation. Radiofrequency catheter ablation in the left atrium can damage autonomic ganglionated plexi, leading to vagal withdrawal, thus resulting in enhanced sympathetic tone. Tako-tsubo cardiomyopathy has not been previously described following radiofrequency catheter ablation.
    Journal of Cardiovascular Electrophysiology 07/2007; 18(6):667-71. · 3.48 Impact Factor
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    ABSTRACT: Although angiography is the gold standard for coronary imaging, its efficacy in outlining diffuse coronary atherosclerosis in diabetic patients remains questionable. We aimed to compare quantitative cineangiographic analysis (QCA) with three-dimensional intravascular ultrasound (IVUS) imaging in type 2 diabetic patients with coronary artery disease. IVUS runs of 104 significant coronary lesions in 88 diabetic patients were performed. Arterial remodeling index was calculated as vessel area at minimal lumen area divided by mean reference vessel area. No difference between the two analysis modes was shown for lesion length and minimal lumen diameter, whereas a significant discrepancy between QCA and IVUS was found for diameter stenosis (10 +/- 9% vs. 41 +/- 8%; P<.001) and vessel diameter (3.01 +/- 0.66 vs. 4.53 +/- 0.70 mm; P<.001). A significant difference on arterial remodeling at lesion site was found between insulin-treated diabetic patients and non-insulin-treated diabetic patients (remodeling index: 0.98 +/- 0.16 vs. 1.07 +/- 0.21; P=.04). Coronary angiographic diagnosis in diabetic patients may be distorted due to a large plaque burden over longer vessel segments and the resulting absence of plaque-free reference segments. This distortion was found to be more pronounced in QCA analysis requiring a reference diameter, whereas volumetric IVUS imaging illustrated coronary artery dimensions more accurately according to anatomic structures. Constrictive arterial remodeling was observed more frequently in type 2 diabetic patients treated with insulin.
    Journal of Diabetes and its Complications 01/2007; 21(6):381-6. · 2.06 Impact Factor
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    ABSTRACT: The renin-angiotensin-aldosterone system and inflammation are supposed to play a key role in the pathogenesis of atrial fibrillation (AF). This retrospective clinical study was intended to assess the influence of drugs with antiinflammatory and/or renin-angiotensin-aldosterone system-modulating properties, namely angiotensin-converting enzyme inhibitors (ACE-Is), angiotensin II receptor blockers (ARBs), and statins, on AF-free survival after AF ablation. The study included 234 patients (23-80 years; 71.8% men) with drug-resistant paroxysmal (n = 165) or persistent AF (n = 69) who either underwent a Lasso-guided segmental pulmonary vein isolation (n = 83) or a CARTO-guided left atrial circumferential ablation (n = 151). Treatment with statins (n = 113), ACE-Is, or ARBs (n = 124), or a combination of a statin and an ACE-I or ARB (n = 75) was started >3 months before ablation and was continued during follow-up. After a median follow-up of 12.7 months, 64% of patients with paroxysmal and 45% of patients with persistent AF were free of AF. Statin use (hazard ratio [HR], 1.06; P = .79), ACE-I or ARB use (HR, 1.12; P = .59), and their combined use (statin + ACE-I/ARB; HR, 1.17; P = .54) did not significantly influence ablation outcome as assessed by Cox regression analysis. In addition, after multivariate adjustment for potential confounders, the examined drugs did not significantly affect ablation outcome. Ablation induced an acute up-regulation of C-reactive protein levels (preablation vs 48 hours postablation, 5.9 +/- 8.1 vs 33.7 +/- 30 mg/L; P < .001) and other inflammatory markers. The examined drugs did not significantly alter baseline levels or ablation-induced up-regulation of inflammatory markers. The routine use of statins, ACE-Is, or ARBs did not result in an improved outcome of AF ablation.
    American heart journal 01/2007; 153(1):113-9. · 4.65 Impact Factor
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    Michael Derntl
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    ABSTRACT: Peer evaluation is a well researched part of innov ative teaching and learning processes. Results relating to measures such as reliability, o r congruence of student/instructor evaluations, vary from study to study due to different standards , students, requirements, and other contextual factors. Despite all these factors and discussions it is generally agreed that the proliferation of we b technologies has boosted the use of this assessment technique. Most papers on this subject try to either justify or reject the use of peer evaluation as part of the teaching/learning process. In contrast, this paper aims to provide a neutral, gen eric view on web-supported peer-evaluation, focusing on how - instead of why - it can be implemented. We present succinct intent and motivations, along with a general model and discuss ion of the typical process.
    01/2006;
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    ABSTRACT: To assess the efficacy of intracoronary brachytherapy with beta-radiation (Sr/Y) for the treatment of long diffuse in-stent restenosis (ISR). As recurrent ISR depends on intimal injury after coronary angioplasty, long in-stent restenotic lesions were defined as lesions with a treatment length >26 mm (lesion length >20 mm plus a treatment margin of 3 mm at each end). Seventy-eight patients with long ISR were treated at our institution with beta-brachytherapy after coronary angioplasty. Patients were irradiated with either an approximate dose of 12 Gy at 1 mm vessel wall depth or with 18 Gy at 1 mm vessel wall depth. Clinical follow-up was available for 69 patients and angiographic follow-up for 65 patients. Late lumen loss (LLL), binary restenosis (stenosis >50%), target lesion revascularization (TLR) and major adverse cardiac events (MACE) were assessed for a follow-up time of 6.6+/-2.2 months. Mean interventional treatment length was 46+/-18 mm. TLR was performed in all 23 patients with binary restenosis (33%). Death of cardiac cause was reported for two patients, one of whom did not undergo TLR. Thus, overall MACE rate was 35%. Recurrent ISR was significantly more frequent in patients with geographic miss. Comparison of the different radiation dose regimens revealed significantly lower LLL in patients irradiated with the higher dose (0.20+/-0.68 mm compared with 0.65+/-0.96 mm, P=0.03). Intracoronary brachytherapy with beta-radiation (Sr/Y) is a safe and effective therapeutic option for the reduction of recurrent ISR in long diffuse lesions. We recommend a high-dose irradiation with 18 Gy at 1 mm vessel wall depth.
    Coronary Artery Disease 09/2004; 15(5):285-9. · 1.11 Impact Factor
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    ABSTRACT: The purpose of this analysis was to evaluate if overdosage during intracoronary irradiation due to overlapped source stepping may result in long-term morphologic changes in vessel anatomy. Baseline angiograms of patients with in-stent restenosis undergoing coronary reintervention followed by intracoronary irradiation with source stepping were analyzed. Overlapping was considered present for the segment with overlapped reference isodose length (RIL) (RIL = segment with > or = 90% of reference dose at 1 mm vessel wall depth). Baseline and 6-months follow-up volumetric intravascular ultrasound (IVUS) analysis were performed for the overlapped segment and for proximal and distal segments of equal length. Overlapping was found in six patients (three patients: (32)P treatment; three patients: (90)Sr/Y treatment); final analysis was performed in four patients. Comparison of the baseline and follow-up IVUS volumetric parameters revealed no significant change in lumen or vessel volumes at segments of overlaps in comparison to proximal and distal reference segments. Increased dosage due to overlapping during source stepping is not associated with morphologic changes in vessel anatomy at follow-up.
    Journal of Interventional Cardiology 06/2004; 17(3):143-9. · 1.50 Impact Factor
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    ABSTRACT: ITF-1697 is a chemically modified LYS-Pro tetrapeptide that corresponds to sequence 113-116 of C-reactive protein. Previous studies have demonstrated significant anti-ischaemic and antithrombotic activity of this tetrapeptide. The aim of this prospective, randomised, double-blind study in patients with acute myocardial infarction undergoing coronary revascularisation was to investigate the safety and efficacy of prolonged intravenous (i.v.) infusion of ITF-1697 at different doses on reduction of infarct size, as assessed by radionuclide imaging. Injection of technetium-99m (Tc99m) was followed by injection of ITF-1697 or placebo bolus and 24-hour infusion in patients with acute myocardial infarction. Percutaneous transluminal coronary angioplasty (PTCA) was performed and succeeded by radionuclide imaging. A second Tc99m injection and radionuclide imaging was performed 7 days after the PTCA or at hospital discharge. The primary efficacy variable was set as the ratio between the myocardial salvage (size of the initial perfusion defect minus the final size of the infarct) and the initial area at risk (myocardial salvage index). Twenty-three patients were included in the study protocol, of whom nine were randomised to the ITF-1967 dose 1 group (loading dose 55 microg/kg i.v., infusion 0.5 microg/kg/min for 24 hours), a further nine to the ITF-1697 dose 2 group (loading dose 110 microg/kg i.v., infusion 1.0 microg/kg/min for 24 hours), and the remaining five to the placebo group. The defined safety variables (adverse events, laboratory parameters, vital signs and clinical outcome) exhibited no relationship to the application of ITF-1697. Comparison of myocardial salvage index revealed no statistical difference within the three groups (p = 0.65). Hypothesis testing on the myocardial salvage as well as the empirical and bias-correct confidence intervals (CIs) revealed significant differences between the ITF-1697 dose 2 group and the placebo group (95% CI 2.75, 18.07). The application of the tetrapeptide ITF-1697 during acute myocardial infarction to reduce infarct size was found to be feasible and safe in this pilot trial.
    Drugs in R & D 02/2004; 5(3):141-51. · 1.35 Impact Factor
  • Coronary Artery Disease - CORONARY ARTERY DIS. 01/2004; 15(5):285-289.
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    ABSTRACT: The implementation of coronary brachytherapy and especially the application of drug-eluting stents for the prevention of in-stent restenosis are of vital importance in the field of interventional cardiology. Despite undeniable benefits of these new methods a potential increased risk for the occurrence of stent thrombosis as a result of the mode of action of these new methods has to be taken into consideration. The prevention of stent thrombosis following coronary brachytherapy and implantation of drug-eluting stents is therefore of particular importance to assure the success of these forward-looking technologies. This article provides an overview of current data regarding the incidence of stent thrombosis following brachytherapy and implantation of drug-eluting stents and it's implication for clinical practice.
    Journal of Interventional Cardiology 01/2003; 15(6):477-83. · 1.50 Impact Factor
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    Michael Derntl
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    ABSTRACT: Web-based Learning Environments (WLEs) are continually enhanced with new features and powerful tools. Nonetheless, it is becoming increasingly complex for students to use and for instructors and administrators to customize them to optimally support their intended use. This might be due to the fact that most of the current WLEs lack intuitive guidance in customizing their features according to users' needs. Striving towards a solution to this quandary, this paper presents a method for providing generic visual specifications of more intuitive, user-centered initialization and application support based on a repository of blended learning patterns. Taking these "Web templates" as implementatio n and usability guidelines, WLE vendors should be capable of keeping closer to the needs of their users.
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    Renate Motschnig, Michael Derntl
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    Michael Derntl
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    ABSTRACT: Blended or technology-enhanced learning continues to be a topic of interest, especially to the educational multimedia community. Particular ly, settings and activities of promotive nature are most interesting and promising as they tend to increase motivation, outcome, and other benefits of participation in courses. Yet most approaches an d theories use different terminology, context, and focus, while conceptually referring to similar underlying values or philosophy. In this respect this paper tries to conceptually integrate typical promotive activities with a repository of blended learning scenarios. The study reveals that, even th ough the works have been conducted completely independently from each other, there are various si gnificant points of overlap and shared intent. We dare to conclude that a good part of studies report ing successful integration of technology into teaching and learning could be traced back to promo tive-activity theory and its underlying values.