Endoluminal application of glass-capped diffuser for ex vivo endovenous photocoagulation

Abstract

Endovenous laser ablation (EVLA) has frequently been used to treat varicose veins for 20 years. In spite of 90˜95% occlusion rates, clinical complications such as burn and ecchymosis still occur due to excessive thermal injury to perivenous tissue. In the current study, a glass-capped diffusing applicator is designed to validate the feasibility of EVLA as an effective therapeutic device by applying circumferential light distribution. The proposed device is evaluated with a flat fiber as a reference in terms of temperature elevation, fiber degradation, and degree of coagulative necrosis after 532 nm-assisted EVLA at 100 J/cm. The diffusing fiber generates a 40% lower maximum temperature with a 90% lower transient temperature change in blood, compared to the flat fiber. Due to low irradiance (13.5 kW/cm ) and wide light distribution, the diffuser tip experiences no significant thermal degradation while severe carbonization occurs at the flat fiber tip. Ex vivo tissue tests verify that the diffusing fiber induces circumferential and consistent tissue denaturation to the vein wall (107.8 ± 7.8 µm) along with 19% vessel shrinkage. The proposed glass-capped diffusing applicator can be a feasible therapeutic device for EVLA with minimal complications by entailing low maximum temperatures and uniform tissue denaturation in the venous tissue.

Concentric photothermal coagulation with basket‐integrated optical device for treatment of tracheal stenosis

“…Although the optical diffuser was developed to deliver laser light radially to treat urethral stricture, the previous study pointed out that out‐of‐center phenomena occurred due to blind deployment of the optical diffuser, irregular urethral structure and lack of centering methods . In addition, various types of fiber tips such bare flat fiber, Tulip‐Tip, NeverTouch, radial fiber and diffusing fiber were used for endovenous laser ablation for treatment of varicose veins . Nonetheless, without any geometric restraints to prevent the fibers from making contact with vein wall, perforations often occur primarily due to overheating from unfavorable tissue contact.…”

“…A number of laser types have been effectively and efficiently used such as Nd:YAG (1064 nm), thulium fiber laser (1940 nm), potassium‐titanyl‐phosphate (KTP, 532 nm) and CO 2 (10.6 μm) lasers . In particular, many scientists have been using optical diffusing fibers to either induce stricture or treat stenosis in tubular tissue such as varicose veins , urethra , seminal duct and trachea in rabbits . However, it is relatively difficult to insert and position the laser device at the right center of lumen to induce a circumferentially homogeneous coagulation in the tissue walls.…”

Real-time co-registered photoacoustic and ultrasonic imaging for early endometrial cancer detection driven by cylindrical diffuser

“…Cyindrical di®users (CD) are widely used in light therapies, such as photodynamic therapy, 18 photoimmunotherapy, 19 photothermal therapy, 20 and photocoagulation. 21 Kang et al proposed a catheter-based CD as a feasible therapeutic tool to photocoagulate endometrial cell layers in an e±cient and safe manner. 22 In previous work by our team, we proposed a PA method for the estimation and reconstruction of 3D light distribution produced by a CD in biological tissue.…”

Integration of optical applicator with balloon catheter for photothermal treatment of biliary stricture

“…In turn, the radial light diffusion from the fabricated fiber entails irreversible tissue denaturation in the tubular tissue structure such as urethra [11]. Due to lower irradiance than the flat-cut fiber (i.e., 13.5 kW/cm 2 for diffuser vs. 64.9 kW/cm 2 for flat fiber), the diffuser reportedly generated up to 50% lower peak temperature and up to 90% thermal gradient in vein [12]. Histological analysis also confirmed that coagulative necrosis was consistently developed around the lumen within 1 mm [11].…”