Arkady Glukhovsky

The New Eng land Jour nal of Medicine pertrophy, and an aortic-valve area of less than 0.6 cm 2 or an aortic-valve index no higher than 0.6 cm 2 per square meter of body-surface area). 2 However, none of these echocardiographic findings have demonstrated the predictive power that Rosenhek et al. report for the degree of valvular calcification and the increase in aortic-jet velocity. Their results add to the existing evidence that an absence of symptoms is an insufficient reason to delay aortic-valve replacement in certain cases. The findings also shed light on the matter of which patients should be considered for early surgery.

With the introduction of the flexible fiber optic endoscope in 1950s visualization of the esophagus, stomach, upper small bowel and colon became possible. The flexible shaft of the instrument carried the fiber optic light bundles, power and the optical elements. It also contained cables, which allowed for control over the direction of the instrument. Therefore, the instrument was of relatively large diameter, making gastroscopy, small bowel endoscopy and colonoscopy an uncomfortable procedure requiring sedation. Recent advances in development of low power complementary metal‐oxide silicon (CMOS) imagers, mixed signal application specific integrated circuit (ASICs) and white light emitting diodes (LEDs) made possible development of a new type of endoscope – the swallowable video capsule. We describe the development of a video‐telemetry capsule endoscope that is small enough to swallow (11×26 mm) and has no external wires, fiber optic bundles or cables. Extensive clinical and healthy volunteer trials have proved the effectiveness of the wireless endoscope in detection of pathologies in the GI tract.

Small bowel endoscopy with existing endoscopes is limited by problems of discomfort and the technical difficulty of advancing far into the small-bowel. Our aim has been to develop and test wireless capsule endoscopy. Wireless endoscopes, in the form of capsules (11 x 33 mm), were constructed by Given Imaging. These were powered by silver oxide batteries and each contained a CMOS imaging chip and miniature processor, white light emitting diodes (LEDs), a short focal length lens, and a miniature transmitter and antenna. Two video frames per second were transmitted, using radio-frequency (approx. 410 MHz), to an array of aerials attached to the body. The array of aerials can also be used to calculate the position of the capsule in the body. The images were stored on a portable recorder carried on a belt and subsequently downloaded for analysis. The batteries allow more than 5 hours of recording, although the capsule generally passes through the whole small bowel in under two hours. Clear video images of the human bowel were recorded from the pylorus to the caecum. Wireless endoscopy, for the first time, allows painless optical imaging of the whole of the small bowel.