[Experimental coronary angioplasty using hematoporphyrin coloration simultaneously with a pulsed laser beam]

The setting up of a reliable method for angioplasty by laser irradiation is based. On the one hand, on the simultaneous control of the observed thermal, mechanical and photochemical effects within the atheromatous material and, on the other, on the demonstration of the absence of effects damaging to the arterial tunica. Theoretical modelling and experimental use have together proved the unique importance of pulsed emission, which strongly reduces thermal diffusion. Labelling of the atheromatous plaque by a hematoporphyrin derivative (HPD), as exemplified in the carcinological process, cancels the superficial reflectivity and strongly reduces the diffusion coefficient in the plaque. It confers on it a spectral absorption characteristic which is the basis of the exact physical coupling between the frequency of the exciting radiation and the absorption which generates vaporization in the pathological material. The preparation of chemically more homogeneous HPD and the spectrometric study of other colouring agents in vivo point to a further development of this technique of angioplasty.