Laser coronary angioplasty: history, present and future.

The efficacy of percutaneous transluminal coronary angioplasty (PTCA) is limited by remaining plaque tissue and the development of restenosis. It has been demonstrated that the restenosis rate is low if a large lumen diameter is achieved after coronary intervention. Debulking of coronary stenoses is a concept to increase the luminal diameter after intervention. Laser angioplasty debulks coronary stenoses by ablation of atherosclerotic plaque. Since the first intravascular laser intervention, the technique has been significantly improved by the use of optimized wavelength, the development of flexible optimally spaced multifiber catheters and an additional saline flush technique. These technical advancements allowed a reduction in the incidence of adverse events, such as the number of dissections and perforations, associated with the use of the laser technique. Coronary laser angioplasty is commonly combined with adjunctive balloon angioplasty to optimize the outcome. Laser coronary angioplasty was not followed by a lower restenosis rate compared with plain balloon angioplasty in lesions without stents, however, a randomized comparison of the techniques including the use of the saline flush technique is not available yet. The value of excimer (acronym for excited dimer) laser coronary angioplasty for treatment of in-stent restenosis is still under investigation. So far, nonrandomized single center studies have not suggested a relevant benefit for this technique used for in-stent restenosis. In nonstented lesions there remain niche indications for laser angioplasty such as the treatment of ostial lesions, diffuse lesions or lesions traversable with a guidewire but not with an angioplasty balloon. Laser coronary angioplasty may also be useful after a failed balloon angioplasty and in patients with chronic total occlusions. The potential advantages of combining laser coronary angioplasty with vaporization of thrombus in patients with acute coronary syndromes are currently under evaluation.

Treatment of in-stent restenosis with excrimer laser coronary angioplasty versus rotational atherectomy

Atherobalation yields improved clinical results for balloon angioplasty (percutaneous transluminal coronary angioplasty, PTCA) in the treatment of diffuse in stent restenosis (ISR).We compared the mechanisms and clinical results of excrimer laser coronary angioplasty (ELCA)versus rotational atherectomy (RA), both followed by adjunct PTCA; 119 patients (158 ISR lesions) were treated with ELCA + PTCA and 130 patients (161 ISR lesions) were treated with RA + PTCA. Quantitative coronary angiographic and planar intravascular ultrasound (IVUS) measurements were performed routinely. In addition, volumetric (IVUS ELCA + PTCA, 14 RA + PTCA). There were no significant between-group differences in preintervention or final postintervention...

Has laser revascularization found its place yet?

Transmyocardial laser revascularization (TMR) is a relatively new therapy for atherosclerotic coronary artery disease. Unlike well established surgical and percutaneous revascularization procedures, TMR is reserved for patients with advanced and severe forms of coronary artery disease that is unsuitable for other forms of revascularization. The results of TMR so far have been controversial with a bias toward steady and incremental adoption as sole therapy or in combination with coronary artery bypass graft surgery. The controversy surrounding TMR is related to the fact that its mechanism of action is not proven beyond a reasonable doubt. It is believed that angiogensis stimulation by the laser beam may be responsible for the relief of angina. However, the marked discrepancy in the symptomatic relief of angina and the increase in myocardial perfusion is not well understood. Other mechanisms proposed include direct perfusion through the laser channels, myocardial damage, denervation of ischemic myocardium and a placebo effect. It is possible that one or more of these mechanism may be responsible at various time intervals for the relief of angina. The challenge of TMR is related to improvement in perioperative outcomes, and long-term survival without worsening of left ventricular function. The achievement of these goals makes TMR an alternative therapy to what was formerly the only therapeutic option for these patients, namely: failed maximum medical therapy.

[Return signal processing and problems of laser angioplasty with optical detection of intravascular objects]. / Obrabotka otrazhennogo signala v zadachakh lazernoi angioplastiki S opticheskoi lokatsiei vnutrisosudistykh obektov.

The paper deals with the development of devices for visualization on intravascular formations by using multifiber optical catheters, describes a scheme for a pilot testing unit based on periodical pulse-acting Nd:YAG laser that operates at the second harmonics (lambda = 532 nm). Analyzes errors while processing the return signal received by intravascular objects, proposes a statistical model which describes the received signal, which permits the development a of block diagram for an optimized device for initial processing of signals.

New technologies in interventional cardiology.

New technologies for interventional cardiology include metallic intraluminal supports (stents), mechanical devices used for plaque removal (atherectomy), and photoablative devices (lasers). Several individual devices in each category are in active clinical investigation and appear to provide safe and effective treatment for many problems that have continued to plague conventional balloon angioplasty. These include failure to dilate eccentric, rigid, or diffuse stenoses; abrupt closure of the dilated segment; and restenosis after successful dilatation. Working with these devices, physicians have learned not only how to use them optimally but a great deal about the biology of restenosis and the manner in which new interventional devices should be evaluated. Although none of the new technologies is likely to replace balloon angioplasty, which has demonstrated broad applicability, success, and safety, the selective use of new devices seems certain to enhance the possibilities for percutaneous transluminal revascularization.

Wire-guided excimer laser coronary angioplasty: instrument selection, lesion characterization, and operator technique.

Laser angioplasty has now been successfully performed on over 2,000 patients worldwide. Two systems (Advanced Interventional Systems, and Spectranetics, Corp.) have now received initial approval from the Food and Drug Administration. As with all new interventional techniques designed as an alternative to balloon angioplasty, there are a variety of instrument related issues that merit consideration in terms of patient selection as well as operator technique. While the ultimate role of laser angioplasty in the percutaneous revascularization of coronary artery disease remains to be established with certainty, laser angioplasty is, in fact, being currently used on a widespread basis as an alternative or an adjunct to balloon angioplasty in a large number of centers worldwide. Industry projections suggest that the use of this technique will increase further over the next decade. Accordingly, the purpose of this article is to discuss specific issues regarding instrumentation, native anatomical considerations, operator technique, and complications that relate specifically to the applied use of this technology as it is currently being used.

Laser angioplasty.

Laser energy has the potential for selective ablation of atherosclerotic plaque through minimally invasive means. As currently practiced, laser angioplasty requires the adjunct of balloon angioplasty in most cases and has limited application compared with more conventional methods of revascularization. However, new advances in guidance systems, delivery devices, and laser sources may allow realization of the full benefit of this technology at some point in the future.

New technologies in interventional cardiology.

This review confines itself to the new technologies that are widely used and that are being tested in formal trials. To date there have been few well-performed trials to compare the technologies, a fact that may have opened the way for the inappropriate use of some of these new technologies. This has allowed enthusiasts to perform procedures with as yet unproven tools no better and possibly worse than balloon angioplasty. New technologies can be broadly divided into three categories depending on their intended role: 1) mechanical removal, such as directional atherectomy, extractional atherectomy, and rotational atherectomy, that is designed to debulk lesions and remove atheromatous material, 2) high-energy removal by laser technologies designed to disobliterate lesions without producing the theoretically damaging lateral stretching of normal balloon angioplasty, 3) intraluminal scaffolding through the use of stents designed to give intravascular support, eg, balloon expandable, self-expanding, and temporary removable devices.

Laser-assisted balloon angioplasty.

At present, the precise applications and indications for laser angioplasty are poorly defined. The method offers a new and effective technique for transluminal recanalization of occluded arterial segments. By creating a lumen to allow the passage of a guidewire across a segment of occluded vessel without creating a dissection, laser angioplasty provides a valuable adjunct to the technology of percutaneous transluminal angioplasty. Laser techniques are being investigated extensively in surgical patients and, although the long-term patency rates are disappointing at present, the technique shows promise as an alternative to bypass operations in poor-risk patients or those with unfavorable surgical anatomy. Improved results of this minimally invasive technique in recanalizing stenoses and short lesions may ultimately redefine the criteria for intervention in this group of patients. We are optimistic that the technique will be developed to offer the vascular surgeon a new modality for treating a larger segment of the patient population suffering from occlusive peripheral vascular disease.

Atherectomy tools for arterial treatment.

When considering limb salvage in patients with failed bypass or angioplasty, the threshold for cost effective use of atherectomy devices is important. Rotational ablation, in these cases, has offered a significant contribution to patient care. Decreased hospital stay, morbidity and mortality, plus improved quality of life are all factors in the calculation. Interventional radiologists, vascular surgeons and interventional cardiologists aim to maintain function, not to perfectly restore original anatomy. In this respect, percutaneous rotational ablation has a role as a useful device when indicated. Indications should include consideration of the pattern of disease and underlying pathology as much as the site and selection of the lesion. The Rotablator may be the device of choice in many coronary cases and it is an important device in planning peripheral revascularization procedures. It provides an option for patients and physicians who wish to achieve minimal invasion with the best possible results.

Holmium YAG laser coronary angioplasty with multifiber catheters.

Excimer lasers are being extensively used for coronary angioplasty along with multifiber over-the-wire catheters. To determine whether another wavelength could be an alternative, the laser-tissue interaction and the clinical usefulness of an infrared laser were studied. The laser consisted of a Holmium YAG pulsed laser coupled into a multifiber catheter. Experimental data from our laboratory showed that this solid state laser had the ability to cut calcified tissue, to be preferentially absorbed by atheroma, and to ablate tissue even when the catheter tip was positioned at a distance from the target. These results were obtained with only minimal thermal effects. After assessment of the efficacy and safety of this technique, laser angioplasty was performed in 53 consecutive patients with totally occluded (40%) or stenosed (mean percent 94) coronary arteries with a mean length of 6 mm. The primary laser and the procedure success rate were 64% and 94%, respectively. Failures were due to inability to advance the catheter against the lesion or to cross the obstruction. Stand-alone laser therapy could be achieved in only 18% of patients. In previous dilatation failures, laser irradiation allowed for subsequent balloon angioplasty to be successfully performed at a lower inflation pressure than that used in the failed dilatation. Complications included abrupt (during the procedure) and early (within 24 hours) vessel closure in 19% of cases, dissection without hemodynamic consequence in 28% and spasm. Reoccluded arteries could all be recanalized with dilatation.(ABSTRACT TRUNCATED AT 250 WORDS)