Theoretical Study on Pressure Damage Based on Clinical Purpura during the Laser Irradiation of Port Wine Stains with Real Complex Vessels

Hao Jia,Dong Li,Bin Chen

doi:10.3390/app9245478

Abstract

Port wine stains (PWSs) are congenital dermal vascular lesions composed of a hyperdilated vasculature. Purpura represented by local hemorrhage from water vaporization in blood during laser therapy of PWS is typically considered a clinical feedback, but with a low cure rate. In this study, light propagation and heat deposition in skin and PWSs is simulated by a tetrahedron-based Monte Carlo method fitted to curved bio-tissues. A curvature-corrected pressure damage model was established to accurately evaluate the relationship between purpura-bleeding area (rate) and laser therapy strategy for real complex vessels. Results showed that the standard deviation of Gaussian curvature of the vessel wall has negative relation with the fluence threshold of vessel rupture, but has positive relation with the effective laser fluence of vessel damage. This finding indicated the probable reason for the poor treatment of PWS, that is, considering purpura formation as a treatment end point (TEP) only leads to partial removal of vascular lesions. Instead, appropriate purpura area ratio with marked effects or rehabilitation should be adopted as TEP. The quantitative correlation between the fluence of a pulsed dye laser and the characteristics of vascular lesions can provide personalized and precise guidance for clinical treatments.

Highlights

Port wine stains (PWSs) are congenital vascular birthmarks characterized by overabundant dermal capillaries or venules, and these marks occur in approximately 0.3% of newborns [1]
The curvature corrected pressure damage (CCPD) model was proposed to examine the relationship between bleeding area and laser fluence in the treatment of real PWS
Vascular lesions with a high stdGC are prone to hemorrhage and purpura formation but have difficulty in achieving Srpu to damage vascular lesions

Summary

Introduction

Port wine stains (PWSs) are congenital vascular birthmarks characterized by overabundant dermal capillaries or venules, and these marks occur in approximately 0.3% of newborns [1]. The effective treatment strategy of PWSs focuses on the laser irradiation of the affected portions of the skin [2,3]. In accordance with selective photothermolysis (SP) theory [4], laser irradiation can irreversibly induce thermal injury to abnormal blood vessels while minimally damaging the surrounding skin tissue. A pulsed dye laser (PDL) with a wavelength of 585 or 595 nm is considered the golden standard for the treatment of PWS lesions [2,5]. According to more than 100 experiments, a laser-irradiated region remains perfused in the absence of purpura of the irradiated vessels. Purpura is typically considered a qualitative clinical treatment end point (TEP) and prognostic indicator for lesion removal [8]

Methods

Results

Conclusion