Anatomically correct positioning of appropriately sized stents does not lead to relevant flow disturbances in the ICA. In the ECA, depending on the position, size, and interstices of the stent, the physiological flow was considerably disturbed when any part of the stent covered the inflow of the vessel. Disturbances were seen when the stent was positioned into the bulb. For clinical application, stent location and size must be carefully determined so that the stent covers the bifurcation completely or is in the ICA only.

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Lasers are used in a wide variety of medical applications. While laser catheters have been developed for highly accurate velocity measurements these are invasive; nonmvasive techniques are more desirable but not as precise. The laser is, however, a great tool for in vitro measurements. Several groups internationally are using the laser in the study of local velocity distribution in microscopic areas of specially constructed models. Laser Doppler anemometry is widely used to measure the local, time-dependent velocities, while phase Doppler anemometry has been developed to measure particle size, distribution and velocity. Most recently, laser analyzer techniques have been developed for analyzing the particle size of two phase flow systems. It has become increasingly important for physicians to visualize blood flow. In addition to the techniques mentioned above, several laser sheet techniques have been developed for precise measurements. This paper presents a short review of laser techniques and shows some applications especially for the laser-Doppler anemometer.

Valvulotomy for in situ vein bypass is commonly performed with a valvulotome. Although the procedure can be controlled through an angioscope, the dangers of intimal damage and valve remnants remain. An experimental study was designed to evaluate angioscopic laser valvulotomy compared with standard mechanical valvulotomy (n = 16). Two different laser probes, a bare 400-microns fibre (n = 20) and a 2-mm hot-tip (n = 26) were tested. Results were investigated by histology and scanning electron microscopy. Hot-tip laser valvulotomy achieved significantly better results than the 400-microns fibre. The Insitucat valvulotome yielded the worst results, with valve remnants in all cases and an 88 per cent rate of intimal damage. It is concluded that laser valvulotomy can be performed simply and safely with a very low incidence of valve remnants and intimal damage.