Évaluation des modifications radio-induites tardives de la microcirculation superficielle.I. Apport clinique du laser doppler cutané

Abstract

Objective. – The changes that occur in the tissular microcirculation after therapeutic irradiation (RT) account for some of the late effects of irradiation, especially on the cutaneous level. As a rule, the methods of exploring the superficial microcirculation only measure blood flow indirectly. Only the Doppler laser can provide direct measurements of blood parameters in vivo in man. Methods. – Thirty women who had been irradiated with 45 + 20 Gy of locoregionel fractionated adjuvant RT for breast cancer developed local radiation-induced fibrosis six years later (± 5). The local microcirculation was measured in the resting state and during thermal stimulation at 42° C, using a Periflux® cutaneous Doppler laser with p413® probes. Three periods of six minutes each were continuously recorded: period 1 (P1) represented basal resting cutaneous perfusion, with the slope p corresponding to the increase in perfusion when two minutes of thermal stimulation at 42° C began; P2 to plateau perfusion during this stimulation; and P3 to perfusion on the return to equilibrium. Each individual was its own control. Results. – In the women treated by RT, the resting microcirculation in the skin underlying an area of late fibrosis rose by a factor of 2 during P1 ( p < 0.001), and the P2/P1 ratio decreased by a factor of 2 ( p < 0.001), compared to the control area. After thermal stimulation, there was no change in p, P2 or P3. Conclusion. – Although a hypovascularization is frequently found in late sequelae of RT, we observed an increase of the cutaneous microcirculation associated with a maladjustment of the endothelial response to a thermal stimulation. These observations seem to reflect the presence of dilated new capillaries of the telangiectatic type, which are macroscopically undetectable.