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Cardiovascular disease is a leading cause of death in all developed countries. In response to this need, endovascular management techniques have been developed across a large range of medical specialties. Minimally invasive percutaneous interventions were initially complex and challenging, but with the continued development of equipment and expertise their use has become routine in many fields. With routine use, it has become important to establish the safety and efficacy of endovascular treatments against the respective "gold standard" procedures, especially in light of their initial intended use for the management of patients at unacceptably high risk for standard therapy only. Such evaluation has to take into account the variety and diversity of devices and techniques, as well as the effects of operator dependability. Endovascular techniques are increasingly recognised as valid alternative management options for a variety of conditions, and it is anticipated that the current trend towards minimally invasive techniques will continue in the future, with moves towards increasingly complex endovascular techniques and hybrid interventions.

Developments in gastrointestinal endoscopy technology are occurring at an exponential rate. Driven by a better understanding of nature, better tools for imaging, measuring, sensing, modeling, and analyzing, as well as more sophisticated researchers and research techniques, developments that used to take decades occur in a fraction of the time. This is as true in medicine as it is in other areas of science; it is especially true in gastrointestinal endoscopy.

In the United States, the Food and Drug Administration has been charged with the job of determining the safety and effectiveness of new drugs and devices. It is a thankless task because there is no reward for taking a balanced risk approach, only criticism for taking too long or approving a product that subsequently has a problem. And making decisions in Washington D.C. that influence the physician's ability to 'do the right thing' for his or her patient regardless of local circumstances doesn't seem to be the socially responsible or ethical thing to do. Devices, of course, are very different from drugs. Their performance is strongly influenced by physician level of skill. A great deal of learning can be accomplished with models. Their mode-of-action can generally be tested before, during and after use. Imaging and accessory tools can significantly reduce risk and trauma as well as enhance their function. Advances in design and performance occur much more rapidly than with drugs. These and other factors suggest that a very different approach is warranted to evaluate their safety and efficacy, as well as to determine when it is ethical to use them on patients. There are many different categories of devices: complex or simple; high inherent risk or low; procedure specific or generic function; etc. Guidelines exist for regulatory approvals in these categories, but the 'bar has been raised' for approval to such an extent that physician, industry and patients groups are questioning the ethics of withholding or delaying the availability of technology and/or adding significantly to its cost without correspondingly significant benefits in reduction of risk.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The rapid acceleration of technology development is outpacing our ability to assess it objectively and competently. Our challenge is to develop new assessment methods that take into account the fast moving nature of technology development while still protecting the patients' and the public interest.

Wires are used for conducting ultrasound energy. These wires achieve optimum properties by creating a multiple material coaxial construction. For example, in a particular embodiment it is desirable to have an elastic core (nitinol) for conducting axial vibrations (sonic or ultrasonic) and a thin stiff cladding (stainless steel) in order to minimize traverse vibrations which result in loss of energy.

Electrical impedance has been one of the many "tools of great promise" that physicians have employed in their quest to measure and/or monitor body function or physiologic events. So far, the expectations for its success have always exceeded its performance. In simplistic terms, physiologic impedance is a measure of the resistance in the volume between electrodes which changes as a function of changes in that volume, the relative impedance of that volume, or a combination of these two. The history and principles of electrical impedance are very nicely reviewed by Geddes and Baker in their textbook "Principles of Applied Biomedical Instrumentation". It is humbling, however, to note that Cremer recorded variations in electrical impedance in frog hearts as early as 1907. The list of potential applications includes the measurement of thyroid function, estrogen activity, galvanic skin reflex, respiration, blood flow by conductivity dilution, nervous activity and eye movement. Commercial devices employing impedance have been and are being used to measure respiration (pneumographs and apneamonitors), pulse volume (impedance phlebographs) and even noninvasive cardiac output.

The design of catheters for intraluminal sensing and imaging is confusing and complicated because of the desire to do so much in such a small space. Developing performance criteria, requires an understanding of the different types of objectives to be achieved, as well as how specific design parameters relate to these objectives.© (1988) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.