Publications (157) View all
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Article: Baroreflex sensitivity in asymptomatic coronary atherosclerosis.
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ABSTRACT: Baroreflex sensitivity (BRS) reflects the effectiveness of cardiac parasympathetic regulation. BRS becomes impaired in stable coronary artery disease (CAD) and after myocardial infarction and carries prognostic information in these patients. Whether impaired BRS is found already in asymptomatic subjects, with subclinical coronary atherosclerosis, has remained elusive. The relationship between BRS and coronary atherosclerosis was evaluated in 31 subjects with high familial risk for CAD but without evidence of angina pectoris or myocardial ischaemia. Single photon emission tomography was performed with (99m) Tc-sestamibi to rule out myocardial perfusion defects at rest and during exercise. BRS was assessed by phenylephrine technique. Coronary atherosclerosis was analysed by quantitative coronary angiography (QCA). Percentage of diameter stenosis (PDS) was calculated separately for LAD, LCX, RCA coronary arteries as well as for proximal (PROX), middle (MID) and distal (DIST) coronary artery regions; and for all coronary artery regions (global PDS). Baroreflex sensitivity averaged 7·8 ± 5·4 ms mmHg(-1) . BRS showed inverse correlation to PDS of the proximal coronary artery segments (r = -0·315; P<0·05) and with the most severe single coronary artery stenosis (r = -0·374; P<0·05). Five (16%) subjects had BRS ≤ 3 ms mmHg(-1) . They had more severe PDS of proximal coronary artery segment than subjects with BRS > 3 ms mmHg(-1) (24 ± 7% versus 13 ± 11%, P<0·05, respectively). Impairment of BRS was found to be associated with the severity of subclinical coronary atherosclerosis in healthy asymptomatic subjects with familial risk of CAD. Asymptomatic subjects with severely blunted BRS may have advanced coronary atherosclerosis.Clinical Physiology and Functional Imaging 01/2013; 33(1):70-4. · 1.33 Impact Factor -
Article: Radiofrequency ablation as initial therapy in paroxysmal atrial fibrillation.
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ABSTRACT: There are limited data comparing radiofrequency catheter ablation with antiarrhythmic drug therapy as first-line treatment in patients with paroxysmal atrial fibrillation. We randomly assigned 294 patients with paroxysmal atrial fibrillation and no history of antiarrhythmic drug use to an initial treatment strategy of either radiofrequency catheter ablation (146 patients) or therapy with class IC or class III antiarrhythmic agents (148 patients). Follow-up included 7-day Holter-monitor recording at 3, 6, 12, 18, and 24 months. Primary end points were the cumulative and per-visit burden of atrial fibrillation (i.e., percentage of time in atrial fibrillation on Holter-monitor recordings). Analyses were performed on an intention-to-treat basis. There was no significant difference between the ablation and drug-therapy groups in the cumulative burden of atrial fibrillation (90th percentile of arrhythmia burden, 13% and 19%, respectively; P=0.10) or the burden at 3, 6, 12, or 18 months. At 24 months, the burden of atrial fibrillation was significantly lower in the ablation group than in the drug-therapy group (90th percentile, 9% vs. 18%; P=0.007), and more patients in the ablation group were free from any atrial fibrillation (85% vs. 71%, P=0.004) and from symptomatic atrial fibrillation (93% vs. 84%, P=0.01). One death in the ablation group was due to a procedure-related stroke; there were three cases of cardiac tamponade in the ablation group. In the drug-therapy group, 54 patients (36%) underwent supplementary ablation. In comparing radiofrequency ablation with antiarrhythmic drug therapy as first-line treatment in patients with paroxysmal atrial fibrillation, we found no significant difference between the treatment groups in the cumulative burden of atrial fibrillation over a period of 2 years. (Funded by the Danish Heart Foundation and others; MANTRA-PAF ClinicalTrials.gov number, NCT00133211.).New England Journal of Medicine 10/2012; 367(17):1587-95. · 53.30 Impact Factor -
Article: Dotted collar placed around carotid artery induces asymmetric neointimal lesion formation in rabbits without intravascular manipulations.
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ABSTRACT: BACKGROUND: Neointimal formation in atherosclerosis has been subject for intense research. However, good animal models mimicking asymmetrical lesion formation in human subjects have been difficult to establish. The aim of this study was to develop a model which would lead to the formation of eccentric lesions under macroscopically intact non-denuded endothelium. METHODS: We have developed a new collar model where we placed two cushions or dots inside the collar. Arterial lesions were characterized using histology and ultrasound methods. RESULTS: When this dotted collar was placed around carotid and femoral arteries it produced asymmetrical pressure on adventitia and a mild flow disturbance, and hence a change in shear stress. Our hypothesis was that this simple procedure would reproducibly produce asymmetrical lesions without any intraluminal manipulations. Intima/media ratio increased towards the distal end of the collar with the direction of blood flow under macroscopically intact endothelium. Macrophages preferentially accumulated in areas of the thickest neointima thus resembling early steps in human atherosclerotic plaque formation. Proliferating cells in these lesions and underlying media were scarce at eight weeks time point. CONCLUSION: The improved dotted collar model produces asymmetrical human-like atherosclerotic lesions in rabbits. This model should be useful in studies regarding the pathogenesis and formation of eccentric atherosclerotic lesions.BMC Cardiovascular Disorders 10/2012; 12(1):91. · 1.52 Impact Factor -
Article: Interference of low frequency magnetic fields with implantable cardioverter-defibrillators.
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ABSTRACT: Abstract Objectives. The aim of this study was to find the electromagnetic interference (EMI) thresholds for several commonly used implantable cardioverter-defibrillators (ICD). Design. Seventeen ICDs were exposed to magnetic fields with different intensities produced by the Helmholtz coil system. Sinusoidal, pulse, ramp, and square-waveforms with a frequency range of 2 Hz to 1 kHz were used. Results. ICD malfunctions occurred in 11 of the 17 ICDs tested. The ICD malfunctions that occurred were false detections of ventricular tachycardia (6/17 ICDs) and ventricular fibrillation (3/17 ICDs), false detection of atrial tachycardia (4/6 dual chamber ICDs) and tachycardia sensing occurring during atrial or ventricular refractory periods (1/17 ICD). In most cases, no interference occurred at magnetic field levels below the occupational safety limits of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Nevertheless, some frequencies using sine, ramp or square waveforms did interfere with certain ICDs at levels below these limits. No EMI occurred with any of the ICDs below the ICNIRP limits for public exposure. Conclusion. Evaluation of EMI should be part of the risk assessment of an employee returning to work after an ICD implantation. The risk assessment should consider magnetic field intensities, frequencies and waveforms.Scandinavian cardiovascular journal: SCJ 07/2012; 46(5):308-14. · 1.07 Impact Factor -
Article: Experimental study on malfunction of pacemakers due to exposure to different external magnetic fields.
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ABSTRACT: Cardiac pacemaker malfunction due to exposure to magnetic fields may cause serious problems in some work environments for workers having cardiac pacemakers. The aim of this study was to find the magnetic field interference thresholds for several commonly used pacemaker models. We investigated 16 pacemakers from three different manufacturers with the frequency range of 2 to 1,000 Hz, using sinusoidal, pulse, ramp, and square waveforms. The magnetic fields were produced by a computer-controlled Helmholtz coil system. Pacemaker malfunction occurred in six of 16 pacemakers. Interaction developed almost immediately after high-intensity magnetic field exposure started. With each waveform, at least two pacemakers exhibited interference. In most exposure settings, there was no interference at magnetic field levels below the international occupational safety limits. Nevertheless, some frequencies using ramp or square waveforms interfered with pacemakers even at levels below public exposure limits. The occurrence of interference depended greatly on the waveform, frequency, magnetic field intensity, and the sensing configuration of the pacemaker. Unipolar configurations were more susceptible for interference than the bipolar ones. In addition, magnetic fields perpendicular to the pacemaker loops were more likely to cause interference than parallel fields. There is a need for further investigations on pacemaker interference caused by different external magnetic fields to ensure safe working environment to workers with a pacemaker.Journal of Interventional Cardiac Electrophysiology 01/2012; 34(1):19-27. · 1.17 Impact Factor
