Next generation catheters for excimer laser coronary angioplasty

Laser angioplasty of peripheral arteries: basic principles, current clinical studies, and future directions

Percutaneous transluminal angioplasty (PTA) is a routine procedure for the treatment of peripheral arterial disease. However, its main limitation is late restenosis occurring at a 1-year rate of 6%-60%. Restenosis arises from injury to the arterial wall including overstretching, compression and rupture of the atherosclerotic plaque during balloon inflation. It is hypothesized that better long-term angioplasty results are observed if atherosclerotic plaques are removed rather than compressed and fractured. Laser angioplasty is one method to remove atherosclerotic plaques. We discuss the principles of lasers, physical properties of laser light, history of laser angioplasty and effects of laser radiation on tissues. Large clinical studies using laser angioplasty are critically assessed. In comparison to conventional PTA, there are some advantages of laser angioplasty: easier passage through chronic and calcified occlusions and according to some studies, better short- and medium-term results regarding limb salvage and management of in-stent restenoses.

The Excimer Laser: Science Fiction Fantasy or Practical Tool?

Nearly 20 years ago, in vitro experiments left no doubt about the fact that laser light can ablate atherosclerotic plaque. The initial enthusiastic results with the technology, particularly in coronary arteries, were followed by reports showing unacceptably high restenosis and complication rates. These poor results were due to the premature application of an underdeveloped technology, a lack of understanding of laser/tissue interaction, and the use of incorrect lasing techniques. Consequently, and without discrimination, all lasers were banned from the catheterization laboratories for nearly a decade. Technological enhancements of the excimer laser, combined with refined catheter lasing techniques, resulted in greater debulking of atherosclerotic material in long superficial femoral artery occlusions. These results triggered the application of the excimer laser technique as an atherectomy tool in more complex lesions below the knee. The multicenter Laser Atherectomy for Critical Ischemia study clearly demonstrated that the excimer laser technology resulted in limb salvage rates >90% in patients with critical limb ischemia (CLI). Furthermore, new clinical results indicate that the excimer laser is very effective in dissolving thrombotic obstructions, redirecting this technology to the coronary field.

The results of the excimer laser in CLI validate the role of the cool laser in treating complex peripheral vascular disease. The results suggest a larger indication for this technology and support a more aggressive use of these interventional techniques in the treatment of this large patient cohort. However, all lasers are not equally effective in debulking atherosclerotic material. Only the athermic process associated with the excimer laser produces a safe and effective endovascular ablation of obstructive atherosclerotic and/or thrombotic material. The appropriate and safe utilization of the equipment and lasing techniques, combined with correct indications and patient selection, will contribute to the successful application of laser-assisted atherectomy in complex peripheral and coronary artery obstructive disease. Unfortunately, little consistent scientific data has been generated to convince the interventional community of the usefulness of excimer laser ablation.

Atherectomy devices: technology update

Atherectomy is a procedure which is performed to remove atherosclerotic plaque from diseased arteries. Atherosclerotic plaques are localized in either coronary or peripheral arterial vasculature and may have different characteristics depending on the texture of the plaque. Atherectomy has been used effectively in treatment of both coronary and peripheral arterial disease. Atherectomy devices are designed differently to either cut, shave, sand, or vaporize these plaques and have different indications. In this article, current atherectomy devices are reviewed.

Selective and self-guided micro-ablation of tissue with plasmonic nanobubbles

BACKGROUND

The accuracy, selectivity, and safety of surgical and laser methods for tissue elimination are often limited at microscale.

MATERIALS AND METHODS

We developed a novel agent, the plasmonic nanobubble (PNB), for optically guided selective elimination of the target tissue with micrometer precision. PNBs were tested in vitro in the two different models of superficial tumors and vascular plaques.

RESULTS

PNBs were selectively generated around gold nanoparticles (delivered to the target tissues) with short laser pulses. Monolayers of cancerous cells and atherosclerotic plaque tissue were eliminated with PNBs with micrometer accuracy and without thermal and mechanical damage to collateral normal tissues. The effect of the PNB was dynamically controlled through the fluence of laser pulses (532 nm, duration 0.5 and 10 ns) and was guided through the optical scattering by PNB.

CONCLUSIONS

Plasmonic nanobubbles were shown to provide precise, tunable, selective, and guided ablation of tissue at a microscopic level and could be employed as a new generation of surgical tools.

The excimer laser: science fiction fantasy or practical tool?

Nearly 20 years ago, in vitro experiments left no doubt about the fact that laser light can ablate atherosclerotic plaque. The initial enthusiastic results with the technology, particularly in coronary arteries, were followed by reports showing unacceptably high restenosis and complication rates. These poor results were due to the premature application of an underdeveloped technology, a lack of understanding of laser/tissue interaction, and the use of incorrect lasing techniques. Consequently, and without discrimination, all lasers were banned from the catheterization laboratories for nearly a decade. Technological enhancements of the excimer laser, combined with refined catheter lasing techniques, resulted in greater debulking of atherosclerotic material in long superficial femoral artery occlusions. These results triggered the application of the excimer laser technique as an atherectomy tool in more complex lesions below the knee. The multicenter Laser Atherectomy for Critical Ischemia study clearly demonstrated that the excimer laser technology resulted in limb salvage rates >90% in patients with critical limb ischemia (CLI). Furthermore, new clinical results indicate that the excimer laser is very effective in dissolving thrombotic obstructions, redirecting this technology to the coronary field. The results of the excimer laser in CLI validate the role of the cool laser in treating complex peripheral vascular disease. The results suggest a larger indication for this technology and support a more aggressive use of these interventional techniques in the treatment of this large patient cohort. However, all lasers are not equally effective in debulking atherosclerotic material. Only the athermic process associated with the excimer laser produces a safe and effective endovascular ablation of obstructive atherosclerotic and/or thrombotic material. The appropriate and safe utilization of the equipment and lasing techniques, combined with correct indications and patient selection, will contribute to the successful application of laser-assisted atherectomy in complex peripheral and coronary artery obstructive disease. Unfortunately, little consistent scientific data has been generated to convince the interventional community of the usefulness of excimer laser ablation.