Biomedical Engineering Reference
In-Depth Information
equivalent one, particularly if the new material has a demonstrated history of
safe use in a similar application. In these cases, the tests are simply designed to
prove the replacement is truly equivalent to the old one.
4.7
Future electrical stimulation devices
Electrical stimulation devices have evolved from pacemakers into defibrillators
and neural stimulators, and will continue to move in new directions to bring
forth numerous new therapeutic treatments. Recently, there has been a rise in the
research of neural interfacing, neural prostheses, and neural signal processing
and imaging, as well as an expansion of neurostimulation (He, 2005). These
research activities are expected to open new areas of electrical stimulation and
sensing technologies to augment physical abilities of healthy individuals and
help neurologically impaired people.
Another exciting development is the application of electrical stimulation to
the gastrointestinal (GI) tract. The first such application for the treatment of
post-operative ileus was reported as early as 1963 (Bilgutay et al., 1963).
Research on gastroparesis, a debilitating gastric motor disorder, led to the
development of Enterra therapy that has been demonstrated to be effective in
suppressing certain symptoms (Abell et al., 2002, 2003).
In the past decade, there has been growing interest in electrical stimulation of
the GI tract as a potential therapy for obesity. Much of the recent work has
focused on the ability of gastric stimulation to modulate activity along the brain±
gut axis in a manner consistent with the down-regulation of feeding. For
example, gastric electrical stimulation (GES) has been shown to modulate
gastrointestinal motility (Sarnelli et al., 2003; Ouyang and Chen, 2007; Song et
al., 2007, 2009; Zhang et al., 2009a), the central nervous system (Qin et al.,
2005, 2007; Sun et al., 2006; Zhang et al., 2009b), and the level of peptides
known to be involved in the regulation of feeding (Tang et al., 2006; Zhang and
Chen, 2006; Xu et al., 2007; Liu et al., 2008). Similar to neurostimulation, the
magnitude of all of these effects depends upon the stimulation targets and
parameters. However, the parameters that appear to be most effective in this area
are outside the range of most implantable neurostimulation devices. Therefore, a
new generation of engineering designs and biomaterials for `gut stimulation'
devices may be required.
It is fair to say that medical device trends are strongly affected by other
technologies. Many research activities of electric stimulation can be attributed to
the successes in other areas. Rapid progress in imaging and navigation tech-
nologies made neurostimulator implantation possible. The wide uses of mag-
netic resonance imaging (MRI) techniques created a need for MRI-compatible
devices. Rapid advances in drug delivery technology helped drive the develop-
ment of drug±device combination products. Sensing, wireless, and IT
technologies combined to provide opportunities to merge biological sensing,
