Method for obtaining a homogeneous light distribution (HLD) in intravascular irradition with laser light, as well as laser catheter to be used in this method, and procedure for the manufacture thereof

摘要

In Excimer Laser Coronary Angioplasty (ELCA), a technique in which the light from an excimer laser is shone via a quartz multi-fibre catheter into coronary arteries at places where they are constricted, homogeneous light distribution (HLD) in intravascular irradiation is obtained by virtue of the fact that the laser catheter, consisting of a coaxial bundle of very fine quartz fibres, is provided at the light emission end of the bundle with a sealing quartz window, which by fusion with the ends of the fibres forms an integral whole therewith. The diameter of the window is adapted to the diameter of the fibre bundle, and the thickness of the window is chosen in such a way that the cones of light coming from the individual quartz fibres overlap within this window. As a result the effect is achieved that on the emission side of the window there is a homogeneous light distribution, comparable with that which would arise if the light were conducted through a single broad fibre. Because of the great homogeneity of the irradiation light so obtained, the so-called "dead spaces" between individual fibres are eliminated, and no marginal zone effects occur. The new laser catheter retains the advantage of the use of a large number of fine fibres, as a result of which a flexible catheter can be obtained, but has eliminated the disadvantage thereof, namely a considerable number of dead spaces.