Endokardiale laser revaskularisation des myokards mittels 20 J einzelpuls holmium laserstrahlung

Endocardial Laser Revascularization (ELR) is a new technique to treat coronary heart disease in a percutaneous, minimally invasive approach. A Holmium laser (λ = 2.1 μm) was developed to emit pulse energies up to 30 J in order to ablate the desired channels in just one single laser pulse. The energy is transmitted by a flexible multimode optical waveguide as required for ELR. Myocardial channel depth was quantified in vitro on porcine heart tissue using pulse energies up to 20 J at pulse durations of 3 and 8 ms, respectively. Tissue morphology was evaluated using polarisation light microscopy to determine thermal and mechanical collateral damage zones. Ablation dynamics were investigated in polyacrylamide (PAA) serving as a transparent tissue model with a pulse energy of 12 J and pulse duration's between 2.2 ms and 8 ms. The ablation process was recorded by high-speed photography (5000 frames/s). Using the same laser pulse energy, the channel lengths were found to be about 25% larger at a pulse duration of 3 ms compared to 8 ms, respectively. A maximal channel depth of 8 mm was created with a laser pulse energy of 16 J and a pulse duration at 3 ms. Thermal mechanical damage zones were found to extent about 500-700 μm around the channel. The ablation dynamics in PAA shows lateral oscillations of the cavity during the laser pulse at all laser parameters investigated. In conclusion, the results of the study are very encouraging and demonstrate the potential of ELR as a catheter based minimal invasive procedure to ablate myocardial channels by single high-energy laser pulses.