Initial clinical experience with a new pulsed dye laser device in angioplasty of limb ischemia and shunt fistula obstructions.

Selective plaque ablation with laser radiation at 405-530 nm in vitro has been reported. We investigated the possibilities of a new pulsed dye laser device for in vivo recanalization of arteries in ischemic lower limbs and stenoses/occlusions of arterio-venous hemodialysis shunt fistulae. A specially designed 9F or 7F multifiber catheter was used for treatment of 10 patients with lower limb artery obliterations and 11 patients with malfunctioning hemodialysis access fistulae (HAF). The recanalization technical success was 5/5 in the iliac arteries (IA), 4/5 in the superficial femoral arteries (SFA), and 11/11 in the HAF. Early re-occlusions occurred in one SFA and one IA, respectively, caused by very bad run-off. There was one clinically insignificant SFA perforation. Additional balloon angioplasty was considered necessary in 10/16 lesions. Mean ankle-arm index increased from 0.68 to 0.97. With two exceptions all HAF patients were re-integrated in the dialysis program. Pulsed dye laser angioplasty promises to be an effective and fast method for plaque ablation/debulking. The first clinical experience confirms previous in vitro results. In particular laser recanalization may become the method of choice for treatment of rigid HAF obstructions and it seems to be superior to vascular surgery or balloon angioplasty alone.

A new concept for a realtime feedback system in angioplasty with a flashlamp pumped dye laser.

The feasibility of using a pulsed dye laser in angioplasty for detection and disintegration of calcified plaques was studied in vitro. A flashlamp-pumped dye laser (495 nm, 2 microseconds) was used as the exciting source for laser-induced-fluorescence (LIF) signals. Spectral data in the 520 nm to 800 nm region of normal intima, calcified plaque and fibro-fatty plaques were analyzed with an optical multichannel analyzer, using the same fiber for energy delivery and fluorescence diagnostic. Good signal to noise ratio and different spectra for different specimens were obtained within only 2 microseconds. The spectral difference is caused by selective reabsorption of oxyhemoglobin in the vessel wall. Time resolved LIF-spectroscopy shows that the fluorescence intensity reaches its maximum value before the maximum laser intensity is delivered. Fluorescence analysis can be performed in less than 300 ns and therefore the laser can be controlled before plasma threshold is reached. The described in vitro results can lead to a clinical useful feedbacksystem for energy control of microseconds lasers in angioplasty if the blood interference effects can be minimized by changing the laser excitation wavelength or staining the tissue.