228 research outputs found
Do we need MR conditional pacemakers?
Magnetic resonance imaging (MRI) is a widely accepted
tool for the diagnosis of a variety of disease states.
However, due to safety concerns the presence of an implanted
cardiac pacemaker is considered to be a contraindication
to MRI in most medical centres. The
increasing number of implanted pacemakers and the
estimated over 50% probability that a pacemaker patient
may be a candidate for an MRI increase the need
for safe scanning of pacemaker patients. Over the last
ten years a major effort has been made to understand
the potential risks. The influences from the three electromagnetic
fields on pacemakers are versatile and will
be summarised. The research in this area has helped to
predict the risks of an MRI scan in patients with conventional
pacemakers, and has also stimulated pacemaker
manufacturers to improve their devices with the
goal of providing MR conditional devices. Since autumn
2008 the first approved MR conditional pacemakers
have been on the market and other devices are likely to
follow this trend.
However, the vast majority of devices are still not
approved for MRI, a situation which will take several
years to change. It is thus important that a solution be
also found for these patients. Several studies including
over 500 patients with a pressing need for MRI have
been performed at different experienced centres. On
the basis of those data various organisations in MRI
fields have proposed guidelines for MRI in patients who
fulfill given requirements. However, at present, non-
MRI modalities should be considered, whenever possible,
for diagnosis in pacemaker recipients with conventional
devices. If other imaging modalities are not
adequate, MRI with careful monitoring and preparation
for adverse events may be considered only at experienced
centres. With the wider availability of MR
conditional devices, the risks of MRI are greatly reduced
and non-tertiary centres will be able to perform
these investigations. In any case, rapid progress in the
field of MR conditional pacing is desirable
Differences in cortical coding of heat evoked pain beyond the perceived intensity: An fMRI and EEG study
Imaging studies have identified a wide network of brain areas activated by nociceptive stimuli and revealed differences in somatotopic representation of highly distinct stimulation sites (foot vs. hand) in the primary (S1) and secondary (S2) somatosensory cortices. Somatotopic organization between adjacent dermatomes and differences in cortical coding of similarly perceived nociceptive stimulation are less well studied. Here, cortical processing following contact heat nociceptive stimulation of cervical (C4, C6, and C8) and trunk (T10) dermatomes were recorded in 20 healthy subjects using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). Stimulation of T10 compared with the C6 and C8 revealed significant higher response intensity in the left S1 (contralateral) and the right S2 (ipsilateral) even when the perceived pain was equal between stimulation sites. Accordingly, contact heat evoked potentials following stimulation of T10 showed significantly higher N2P2 amplitudes compared to C6 and C8. Adjacent dermatomes did not reveal a distinct somatotopical representation. Within the assessed cervical and trunk dermatomes, nociceptive cortical processing to heat differs significantly in magnitude even when controlling for pain perception. This study provides evidence that controlling for pain perception is not sufficient to compare directly the magnitude of cortical processing [blood oxygen level dependence (BOLD) response and amplitude of evoked potentials] between body sites. © 2013 Wiley Periodicals, Inc
Initial experience with magnetic resonance imaging-safe pacemakers: A review
Due of its superior soft tissue imaging capabilities, magnetic resonance imaging (MRI) has become the imaging modality of choice in many clinical situations, as illustrated by the tremendous growth in the number of MRIs performed over the past 2 decades. In parallel, the number of patients who require pacemakers or implantable cardiac defibrillators is increasing as indications for these devices broaden and the population ages. Taken together, these phenomena present an important clinical issue, as MR scans are generally contraindicated—except in urgent situations—in patients who have implanted cardiovascular devices. Potentially deleterious interactions between the magnetic fields and radio frequency (RF) energy produced by MR equipment and implantable devices have been identified, including inhibition of pacing, asynchronous/high-rate pacing, lead tip heating, and loss of capture. New devices that incorporate technologies to improve MR safety in patients with pacemakers have recently received approval in Europe and are under evaluation in the United States. Initial data from these devices suggest that these devices are safe in the MRI environment
Occipital transcranial direct current stimulation in episodic migraine patients: effect on cerebral perfusion
Cerebral blood flow differs between migraine patients and healthy controls during attack and the interictal period. This study compares the brain perfusion of episodic migraine patients and healthy controls and investigates the influence of anodal transcranial direct current stimulation (tDCS) over the occipital cortex. We included healthy adult controls and episodic migraineurs. After a 28-day baseline period and the baseline visit, migraine patients received daily active or sham anodal tDCS over the occipital lobe for 28Â days. All participants underwent a MRI scan at baseline; migraineurs were also scanned shortly after the stimulation period and about five months later. At baseline, brain perfusion of migraine patients and controls differed in several areas; among the stimulated areas, perfusion was increased in the cuneus of healthy controls. At the first visit, the active tDCS group had an increased blood flow in regions processing visual stimuli and a decreased perfusion in other areas. Perfusion did not differ at the second follow-up visit. The lower perfusion level in migraineurs in the cuneus indicates a lower preactivation level. Anodal tDCS over the occipital cortex increases perfusion of several areas shortly after the stimulation period, but not 5Â months later. An increase in the cortical preactivation level could mediate the transient reduction of the migraine frequency.Trial registration: NCT03237754 (registered at clincicaltrials.gov; full date of first trial registration: 03/08/2017)
The use of happiness research for public policy
Research on happiness tends to follow a "benevolent dictator" approach where politicians pursue people's happiness. This paper takes an antithetic approach based on the insights of public choice theory. First, we inquire how the results of happiness research may be used to improve the choice of institutions. Second, we show that the policy approach matters for the choice of research questions and the kind of knowledge happiness research aims to provide. Third, we emphasize that there is no shortcut to an optimal policy maximizing some happiness indicator or social welfare function since governments have an incentive to manipulate this indicator
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