Beat Ott

Comparative in vitro study of tissue welding using a 808 nm diode laser and a Ho:YAG laser.

Abstract. In vitro porcine arteries and veins have been welded end-to-end using either a 808 nm diode laser combined with an indocyanine green enhanced albumin solder, or with a continuous-wave (cw) Ho:YAG laser without biological solder. The vascular stumps were approached to each other over a coronary dilatation catheter in order to obtain a precise alignment and good coaptation. Standard histology revealed for both welding techniques lateral tissue damage between 2 and 3 mm caused by laser-induced heat. Good solder attachment to the tissue was observed by the use of a scanning electron microscope. The vessels soldered with the 808 nm diode laser using albumin solder showed considerably higher tensile strength (1 N compared to 0.3 N) than vessels welded exclusively by Ho:YAG laser radiation. In contrast, leaking pressure (350±200 mmHg) and bursting pressure (457±200 mmHg) were found to be independent of the welding technique used. This study demonstrates that fast (total welding time about 2–5 min), stable and tight microvascular anastomosis can be achieved with the use of a dye-enhanced albumin laser soldering technique and an ancillary coronary dilatation catheter.

Combined endoscopic erbium:YAG laser goniopuncture and cataract surgery

Purpose: To study the safety and efficacy of endoscopic erbium:YAG (Er:YAG) laser goniopuncture combined with cataract surgery to treat glaucoma. Setting: Department of Ophthalmology, Albert‐Ludwigs‐University Freiburg, Freiburg, Germany, and Institute of Applied Physics, University of Bern, Bern, Switzerland. Methods: In this nonrandominized clinical trial, 20 eyes of 20 patients with cataract and glaucoma were treated by combined phacoemulsification and Er:YAG goniopuncture. The primary study endpoints were intraocular pressure (IOP), visual acuity, and number of antiglaucoma drugs 1 year after surgery. Two‐ and 3‐year postoperative data were also measured. This prospective treatment arm was compared to a retrospective inclusion‐matched control group treated by cataract surgery alone. Results: The mean IOP dropped by 30% (23.5 mm Hg ± 3.9 [SD] to 16.3 ± 2.7 mm Hg) after 12 months in the laser‐treated group (P<.0001) and by 9% (19.8 ± 1.3 mm Hg to 18.1 ± 1.8 mm Hg) in the control group (P = .12). After 3 years, the mean IOP in the laser group was 15.0 ± 2.0 mm Hg. The mean number of antiglaucoma drugs needed decreased from 1.6 ± 0.9 to 0.5 ± 0.8 in the laser group (P<.0001) and from 1.0 ± 0.9 to 0.8 ± 0.9 in the control group (P = .21). Anterior chamber hemorrhage occurred in 12 eyes after laser treatment and resolved within 72 hours in all but 1 patient who was on warfarin sodium (Coumadin®) therapy. There were no cases of hypotony in either group. Conclusions: Endoscopic Er:YAG laser goniopuncture was a successful adjunct to cataract surgery in glaucoma patients. Sustained IOP reduction was achieved with few postoperative complications.

Acute and chronic effects of Transmyocardial laser revascularization in the nonischemic pig myocardium by using three laser systems

Transmyocardial laser revascularization (TMLR) improves symptoms in patients with coronary heart disease. It is based on the hypothesis of direct perfusion of ischemic myocardium by means of laser‐created channels. Three different lasers were used to study alternative effects on myocardium.

Laser balloon vascular welding using a dye-enhanced albumin solder

Porcine posterior tibial arteries (n equals 50) and saphenous veins (n equals 32) have been welded end-to-end using an 808 nm diode laser combined with an indocyanine green enhanced albumin solder. For comparison, the same welding procedure has been performed with a Holmium:YAG laser without solder. Both lasers were running in continuous wave (cw) regime at a power limited below 1.2 W. The vascular stumps were approached to each other over a coronary dilatation catheter in order to obtain a precise alignment. The balloon catheter simplified vessel handling and the tight vessel positioning prevented a solder penetration into the lumen. Standard histology revealed for both welding techniques a lateral tissue damage between 2 and 3 mm. The vessels welded with the 808 nm diode laser using albumin solder showed considerably higher tensile strength (1 N compared to 0.3 N) than vessels welded exclusively by Ho:YAG laser radiation. In contrast, leaking pressure (350 +/- 200 mmHg) and bursting pressure 457 +/- 200 mmHg) were independent of the welding technique used.

Laser soldering of articular cartilage

The surgical treatment of full thickness cartilage defects in the knee joint remains a therapeutic challenge. Recently, new techniques for articular cartilage transplantation, such as mosaicplasty, have become available for cartilage repair. The long-term success of these techniques, however, depends not only on the chondrocyte viability, but also on a lateral integration of the implant. We evaluated the feasibility of cartilage welding using albumin solder that was dye-enhanced to allow coagulation with 808 nm laser diode irradiation. Therefore circular cartilage defects (1-2 mm depth and 6 mm diameter) were made and subsequently repaired using healthy cartilage grafts, which were solder welded through the graft. Conventional histology was compared with viability staining to precisely determine the extent of thermal damage after laser welding.

In vitro and in vivo retinal surgery with an Er:YAG laser

Membranes developing on the inner surface of the retina (epiretinal membranes) occur under a number of circumstances, including proliferative retinopathy, ocular inflammation, nonproliferative vascular disorders, after penetrating injury, associated with rhegmatogenous retinal detachment and even after successful retinal reattachment.