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At least 19 recordsLinked to original sources

PubMed1988

Laser angioplasty.

Laser technology clearly offers new approaches to the treatment of cardiovascular disease. The ability to transmit intense laser energy through optical fibers may allow precise ablation of pathologic cardiovascular tissues. This potential has stimulated extensive research on laser vaporization of atherosclerotic plaque, or laser angioplasty. Despite the preceding several years of research, there is currently no widespread laser angioplasty system in clinical use. The goal of complete atherosclerotic plaque vaporization without damage to the underlying arterial wall still remains elusive. This article reviews multiple different approaches to the development of laser angioplasty systems. It is too early to predict if all (or any) of these systems will be perfected to the degree necessary to provide cardiologists with a safe and effective laser angioplasty system. It is also difficult to predict the effect that the technologically simpler mechanical recanalization devices and arterial stents will have on laser angioplasty development. Nevertheless, laser angioplasty remains an exciting and promising approach for intravascular recanalization by vaporization of atherosclerotic plaque.

Cardiovascular Diseases↗

PubMed1990

Current status of laser angioplasty.

Laser energy transmitted through fiberoptic systems can recanalize totally occluded peripheral arteries and improve extremity perfusion in selected patients with peripheral vascular disease. Such a technique is obviously appealing in that it (1) reduces the morbidity currently associated with the surgical treatment of symptomatic peripheral atherosclerosis, and (2) allows treatment of patients currently excluded from therapy by the presence of other severe medical problems or relatively mild symptoms. Unfortunately, current delivery systems allow recanalization of only a small channel by laser energy alone, and channel enlargement using balloon dilation is usually required. Clinical trials of laser angioplasty (laser-assisted balloon angioplasty) have shown acceptable results in the treatment of stenosis or short occlusions in the iliac and superficial femoral arteries, but results in patients with long occlusions or disease below the knee remain well below the results achieved by standard surgical therapy. Thus the impact of laser angioplasty on the treatment of peripheral vascular disease is limited at present and much work remains to be done to further develop this exciting new therapy for the treatment of peripheral vascular disease.

Angioplasty, Balloon↗

PubMed1992

[Acute and long-term results of coronary Excimer laser angioplasty].

Laser and catheter technology have been considerably improved within the first 2 years of the clinical use of coronary excimer laser angioplasty. Furthermore, patient selection has changed due to increasing operator experience. We report on the acute- and long-term results achieved in 163 patients in three subgroups with different system parameters and catheter technology. In the initial series 1 (N:60) a prototype catheter with a diameter of 1.4 mm was used. In series 2 and 3, we employed improved transmission devices with 1.3, 1.5 or 1.8 mm. In series 3 the pulsewidth was increased from 60 ns to 115 ns. The target vessel was the LAD in 68%, the LCX in 10%, and the RCA in 21%. According to the AHA/ACC Lesion classification there were 13% type A, 26% type B1, 55% type B2, and 5% type C lesions. Stand-alone laser angioplasty was performed in 23/60 (38%), 24/40 (60%), and 34/64 (53%) in series 1, 2, and 3, respectively. Additional balloon angioplasty was necessary in 32, 11, and 21 interventions. Failure of laser angioplasty occurred in five patients of series 1 and 2, and nine patients of series 3. Frequently observed complications included coronary spasm in 18 to 32%, dissections in 16% to 33%, and vessel closure in 18 to 27%. Myocardial infarction occurred in three patients in the first and one patient of the second and third series. There was one in-hospital death in series 1 and 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Laser↗

PubMed1989

Development and evaluation of spectral classification algorithms for fluorescence guided laser angioplasty.

Laser angioplasty, or the ablation of atherosclerotic plaque using laser energy, has tremendous potential to expand the scope of nonsurgical treatment of obstructive vascular disease. Clinical laser angioplasty, however, has been hindered by an unacceptable risk of vessel perforation. Laser-induced fluorescence spectroscopy can discriminate atherosclerotic from normal artery and may therefore be capable of guiding selective plaque ablation. To assess the feasibility of utilizing spectral information to discriminate arterial tissue type, several classification algorithms were developed and evaluated. Arterial fluorescence spectra from 350 to 700 nm were obtained from 100 human aortic specimens. Seven spectral classification algorithms were developed with the following techniques: multivariate linear regression, stepwise multivariate linear regression, principal components analysis, decision plane analysis, Bayes decision theory, principal peak ratio, and spectral width. The classification ability of each algorithm was evaluated by its application to the training set and to a validation set containing 82 additional spectra. All seven spectral classification algorithms prospectively classified atherosclerotic and normal aorta with an accuracy greater than 80 percent (range: 82-96 percent). Laser angioplasty systems incorporating spectral classification algorithms may therefore be capable of detection and selective ablation of atherosclerotic plaque.

Algorithms↗

PubMed1989

System design considerations for laser angioplasty.

Laser angioplasty, or the use of laser radiation to vaporize or remove obstructure atherosclerotic plaque, has been an active area of research for the past several years. This article reviews current design considerations for developing a safe, effective clinical laser angioplasty system. The choice of laser, fiber, and catheter determines the performance characteristics of such a system. The laser provides the power source for ablative radiation, the fiber furnishes a means of transmitting the laser radiation, and the catheter provides a way of directing the fiber at the target tissue. Other considerations, such as the need for feedback control of laser ablation and the planned application of the system in the coronary or peripheral circulation, also determine the ultimate design.

Journal Article↗

PubMed1990

Experimental analysis of sapphire contact probes for Nd-YAG laser angioplasty.

Laser angioplasty may offer percutaneous recanalization of occluded vessels where conventional guidewire and balloon techniques fail. Metal laser thermal angioplasty probes may, however, cause excessive thermal damage due to high tip temperatures (greater than 400.C). Therefore, contact probes made from artificial sapphire crystal designed for general laser surgery are currently being evaluated for use in laser angioplasty with continuous wave Nd-YAG energy. The sapphire modifies the laser energy in various ways, and this paper examines the physical characteristics of five types of rounded sapphire probe (SMTR, MTR, MTRL, OS, LT) and how these properties are affected by clinical usage. The laser beam profile emitted by these probes demonstrates a focal spot 1-2 mm in front of the tip. However, the forward transmission of Nd-YAG energy through the sapphires varied (SMTR, 85%; MTR, 83%; MTRL, 75%; OS, 54%; LT, 69%). Probe heating occurs owing to energy absorption within the sapphire. The surface temperature of the sapphires was measured in air by infrared thermography and the hottest region within the probes localized by an isothermographic technique. At energy settings used clinically (20 J, 10 watts for 2 s) the SMTR, MTR, and MTRL probes exhibited higher temperature rises (94-112.C) than the OS and LT probes (30.C), and heating was localized to the front surface of the former probes. Peak sapphire temperatures remained lower than those of metal probes even at higher energies. After clinical use, the MTR probe demonstrated reduced transmission, beam defocusing, and increased heating, due to surface pitting. Thus, recanalization with sapphire probes occurs by a combination of photothermal and contact thermal effects that are localized to the probe tip and may reduce the degree of thermal injury associated with metal probes. Understanding these basic properties is important to the application and development of contact probes for laser recanalization.

Aluminum↗

PubMed1992

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.

Angioplasty, Laser↗

PubMed1988

Perforation thresholds and safety factors in in vivo coronary laser angioplasty.

Laser angioplasty can cause early (acute perforation) or late (stenosis or aneurysm) complications. To find how much intravascular laser energy can be delivered via a 100 microns core optical fibre passed down a balloon angioplasty catheter without causing angiographic abnormalities up to 10 days later, argon laser energy was delivered percutaneously under radiographic screening to the coronary circulation of 12 normal closed chest dogs. With the balloon inflated, sequential laser pulses were delivered to the same site. Angiograms were recorded before, immediately, and again at one week, after laser delivery. There were two laser-induced perforations (both fatal). Mechanical perforation with the 100 microns fibre occurred four times, but there were no haemodynamic sequelae. To find the acute perforation threshold of similar sized arteries to energy delivered via the bare 100 microns core fibre, the tip of which was held in contact with the luminal surface, 32 argon laser pulses were delivered transluminally in vivo to separate sites in normal rabbit iliac and canine coronary arteries. The acute perforation threshold with energy delivered via the angioplasty catheter lay between 6 and 10 J and that without the balloon angioplasty catheter lay between 3 and 4 J. After delivery of up to 6 J via a balloon angioplasty catheter, there were no angiographic abnormalities at one week. Fibre optic transluminal delivery of laser energy may improve the primary success rate of, and perhaps widen the indications for, coronary angioplasty.

Angioplasty, Balloon↗

PubMed1986

Preferential light absorption in atheromas in vitro. Implications for laser angioplasty.

Laser angioplasty, the in situ ablation of arterial obstructions with laser radiation, has been demonstrated in animal models and early clinical trials. A problem with this technique, however, is the possibility of thermal damage to adjacent or underlying normal tissues that also absorb the radiation. Using a spectrophotometer with an integrating sphere and a specially constructed tunable-dye laser-based spectrophotometer, we evaluated the transmittance and remittance of human cadaveric atheromas and adjacent normal aorta from 250 to 1,300 nm to identify wavebands where there is preferential light absorption by atheromas. Data were analyzed by both the Kubelka-Munk formalism and a Beer's law model. Both methods indicate that atheromas absorb more than normal aorta between 420 and 530 nm. At 470 nm the average Kubelka-Munk absorption coefficient of atheromas from 10 cadavers was 54 +/- 9 cm-1 compared with 26 +/- 6 cm-1 for normal aortic specimens from seven cadavers. Yellow chromophores responsible for the atheroma absorbance were extractable with xylenes. Thin-layer chromatography and absorption spectra identified the extracted chromophores as predominantly consisting of a mix of carotenoids, which are known constituents of atheromatous lesions. Preferential absorption of blue light by carotenoids in atheromas may permit selective ablation of atheromatous obstructions with appropriate pulses of laser radiation.

Absorption↗

PubMed1989

[Laser angioplasty].

Laser energy is capable of breaking up plaques of atheroma to clear obstructed arteries. Laser rays are transmitted by optic fibers, fine and flexible, or bundles of fibers. In order to avoid perforation of the arterial wall, major difficulty and pitfall of this technique, a centering balloon is used or an absorption gradient between plaque and normal tissue, or improved guiding devices such as angioscopy, ultrasounds or detection of the atheroma by spectroscopy. The laser energy may also be transformed into heat, procedure carried out by thermoplasty. In order to avoid the drawbacks of the cutting end of the bare optic fibers, it may be covered with sapphire optics which conducts well laser energy. Arterial and coronary disobstructions were performed by so called continuous lasers, such as Argon, YAG of pulsed laser such as Excimer or color lasers. These are selectively absorbed by the atheroma and operate according to a computerized system after detection of atheromatous plaques by spectroscopy. Excellent results have recently been obtained with such a system on short and long term complete peripheral arterial obstructions.

Arterial Occlusive Diseases↗

PubMed2002

Laser angioplasty and laser-induced thrombolysis in revascularization of anomalous coronary arteries.

Acute coronary syndromes such as unstable angina and myocardial infarction are attributed to a pathophysiologic process that involves rupture of atherosclerotic plaque and subsequent thrombosis. Percutaneous intervention of anomalous coronary arteries in patients who present with acute coronary syndromes impose unique technical challenges related to the specific anatomic course and morphology of these vessels. Selection of appropriate guiding catheter configuration, choice of supportive guidewire, and proper delivery and activation of debulking devices and stents are important steps toward achieving adequate results. Excimer laser angioplasty is a debulking technology for removal of atherosclerotic plaque and associated thrombi. To date, application of laser angioplasty in anomalous coronary arteries is unreported. We herein present clinical data and discuss technical aspects related to performance of excimer laser angioplasty in three symptomatic patients with acute coronary syndrome, two having an anomalous right coronary artery and one with an anomalous circumflex artery. The delivery of laser energy in these cases resulted in rapid thrombolysis of an occlusive thrombus, successful debulking of the underlying atherosclerotic plaque, facilitation of adjunct balloon angioplasty and stenting, and ultimately, improved clinical condition.

Aged↗

PubMed1987

Argon laser angioplasty with a laser probe.

A preliminary basic study of argon laser angioplasty with the use of a specially designed probe is presented. Arterial specimens were harvested from 10 amputated lower extremities. The studies included the evaluation of coaxial laser angioplasty in 10 partially or totally occluded arteries; the observation of the effect of perpendicularly applied laser energy on 35 thrombi, 54 soft and 10 hard atherosclerotic, and 51 normal arterial walls; the comparison of laser energy requirements for coaxial vessel lumen enlargement or recanalization vs. perpendicular penetration in 10 occluded, hard atherosclerotic arteries; and the spectrographic analysis of calcium density gradient in two specimens. The results showed that the power required for vessel lumen enlargement was 10 +/- 6 J/mm of atherosclerotic vessel (mean +/- standard deviation). The probe followed the original arterial lumen, did not perforate the vessel wall, and created a smooth, enlarged path. The power required to penetrate perpendicularly to a similar depth for thrombi, soft and hard atherosclerotic plaques, and normal arterial walls was 15 +/- 4, 30 +/- 15, 65 +/- 32, and 246 +/- 123 J/mm, respectively. In the hard calcified specimens, laser energy required for coaxial lumen enlargement or recanalization was significantly less than that for perpendicular penetration (p less than 0.05), which correlated with the calcium density map indicating an increase from inside to outside.

Arterial Occlusive Diseases↗

PubMed1990

Coronary excimer laser angioplasty: reduced complications and indium-111 platelet accumulation compared with thermal laser angioplasty.

The relative safety and thrombogenicity of pulsed excimer and thermal laser angioplasty systems were compared in 20 normal coronary artery segments in a total of seven pigs. Using similar over the wire catheter systems and laser delivery periods of 3 to 5 s, thermal laser angioplasty was achieved with a 1.3 mm metal probe heated with 10 W of continuous argon laser energy and excimer laser angioplasty was performed with a 4.5F excimer laser catheter consisting of 13 concentrically arranged 200 microns fiber optics delivering 35 to 40 mJ/mm2 of xenon chloride (308 nm) excimer laser irradiation at a repetition rate of 25 to 30 Hz and a pulse duration of 120 ns. On angiography, the incidence of vessel perforation (1 in 10 versus 3 in 10) and abrupt vessel closure (0 in 10 versus 2 in 10) was less with excimer compared with thermal laser angioplasty. Macroscopically, there was a greater incidence of mural and occlusive thrombus formation after thermal laser than after pulsed excimer laser angioplasty. Histologic examination confirmed that this thrombogenicity was associated with greater charring and coagulation necrosis of the media. Quantitative indium-111-labeled platelet deposition was significantly increased after thermal laser angioplasty (median 87.2 x 10(6)/cm length) compared with excimer-treated (0.4 x 10(6)/cm length) or control (1.2 x 10(6)cm length) segments (p less than 0.001). Thus, excimer laser angioplasty was found to result in fewer complications and, as a consequence, less thrombosis and platelet accumulation than did thermal laser angioplasty.

Angioplasty, Balloon, Coronary↗

PubMed1994

Clinical results of coronary excimer laser angioplasty: report from the European Coronary Excimer Laser Angioplasty Registry.

From January 1991 to January 1993 the clinical and angiographic data of 470 patients were included in the European Coronary Excimer Laser Angioplasty Registry. Symptoms were CCS class 3 in 23% and CCS class 4 in 14.7%; unstable angina was present in 14.7% and 6.6% of patients had acute myocardial infarction. Of 477 treated lesions, 60% were type B2, and 19% type C. The lesion was located in the LAD in 61%, in the LCX in 16%, in the RCA in 20%, in a protected left main stem in 1.3% and in a saphenous vein graft in 2.5%, respectively. Failure of laser angioplasty occurred in 56 (12%) interventions. By multivariate analysis failure was associated with the intention to treat long segmental lesions (risk ratio (RR) 3.6, confidence interval (CI) 2.9 to 4.4; P = 0.0005), segments with severe prestenotic tortuosity (RR 3.5, CI 2.4 to 4.6; P = 0.02) and total occlusions (RR 2.1; CI 1.4 to 2.8; P = 0.05). Complications included vasospasm (13.4%), dissection (14.7%), flow limiting dissection (4%), reclosure (7.8%), and perforation (1.9%). Myocardial infarction occurred in 2.1%, CABG was requested in 1.9%, and the mortality was 1.5%. Procedural success was achieved in 89%. Individual morphological criteria for a reduced procedural success were the presence of a thrombus (RR 6.4; CI 5.0 to 7.7; P = 0.007) and vessel calcification (RR 2.6; CI 1.9 to 3.2; P = 0.005). Procedural success was slightly lower in type C lesions (86%) than in type B2 (88%) type B1 (95%), and type A lesions (92%), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗

PubMedDate not supplied

Excimer laser angioplasty.

Excimer laser angioplasty is one of the newest procedures being used in interventional cardiology. Because of persistently high rates of restenosis with conventional balloon angioplasty (which may be attributed to the acceleration of atherosclerosis by remodeling and dilatation of diseased arteries) alternatives to remove and debulk atheromatous plaque are being explored. Among these, excimer laser angioplasty (ELA) has been developed as a modality that offers an alternative to percutaneous transluminal coronary angioplasty. The laser energy is delivered via fiberoptics to the target lesion and the plaque material is rendered into a gaseous state (vaporized) by breaking the molecular bonds. With proper training and patient selection, ELA has complication rates that are no higher than conventional balloon angioplasty. Preliminary data indicate that the laser is most successful in treating lesions that are not well treated with conventional balloon angioplasty. These include saphenous vein graft lesions, aorto-ostial lesions, long lesions (> 10 mm in length), moderately calcified stenoses, total occlusions, and percutaneous transluminal coronary angioplasty dilitation failures. The purpose of this article is to review the history and physics of ELA and to provide the nursing professional with an understanding of how the procedure is performed. Nursing considerations when caring for the patient undergoing this procedure are provided.

Aged↗

PubMedDate not supplied

The effect of interventional treatment in acute myocardial infarction on ST resolution: a comparison of coronary angioplasty with excimer laser angioplasty.

The treatment methods for acute myocardial infarction (MI) have started to change in the new millennium. Myocardial perfusion (ST-segment resolution) is the target rather than achieving TIMI-III flow in the infarct-related artery. In this study the authors compared the effect of percutaneous transluminal coronary angioplasty (PTCA) and excimer laser angioplasty (ELCA), which was accepted as one of the thrombolysis methods, on ST-segment resolution. A stent was applied after ELCA to 36 patients (4 women, 32 men; mean age 50.44 +/-9.8 years) in group I and a stent was applied after balloon angioplasty to 44 patients (5 women, 39 men; mean age 50.77 +/-12.2 years) in group II. Fisher's exact test was used in the analysis of data, and p<0.05 was accepted as significant. There was no difference between the groups with respect to symptom duration, time to angioplasty, risk factors, infarct localization, stent diameter, and length. TIMI-III flow was achieved in 33 patients (92%) in group I and in 40 patients (91%) in group II. There was no statistical difference in TIMI flow between the groups. In group I, complete ST resolution was observed in 75% (27/36) of the patients, partial resolution in 22% (8/36), and resolution was unsuccessful in 3% (1/36). In group II, complete, partial, and unsuccessful ST resolution were 41% (18/44), 45% (20/44), and 14% (6/44), respectively. The mean ST resolution was 82.78 +/-11.8% in group I and 66.36 +/-10% in group II (p=0.001). ST segment resolution, which is a good predictor of tissue perfusion, was higher with ELCA than with balloon angioplasty. These findings should be supported by large randomized studies.

Adult↗

PubMed1999

Laser angioplasty of restenosed coronary stents: results of a multicenter surveillance trial. The Laser Angioplasty of Restenosed Stents (LARS) Investigators.

OBJECTIVES: This study evaluated safety and efficacy of excimer laser angioplasty for treatment of restenosed or occluded coronary stents. BACKGROUND: Balloon angioplasty of in-stent restenosis is limited by a high recurrence rate. Debulking by laser angioplasty is a novel concept to treat in-stent restenosis. METHODS: A total of 440 patients with restenoses or occlusions in 527 stents were enrolled for treatment with concentric or eccentric laser catheters and adjunctive balloon angioplasty. RESULTS: Laser angioplasty success (< or =50% diameter stenosis after laser treatment or successful passage with a 2.0-mm or 1.7-mm eccentric laser catheter) was achieved in 92% of patients. Adjunctive balloon angioplasty was performed in 99%. Procedural success (laser angioplasty success followed by < or =30% stenosis with or without balloon angioplasty) was 91%. There was neither a significant difference in success with respect to lesion length, nor were there differences between small and large vessels or native vessels and vein grafts. Success was higher and residual stenosis lower using large or eccentric catheters. Serious adverse events included death (1.6%, not directly laser catheter related), Q-wave myocardial infarction (0.5%), non-Q-wave infarction (2.7%), cardiac tamponade (0.5%) and stent damage (0.5%). Perforations after laser treatment occurred in 0.9% of patients and after balloon angioplasty in 0.2%. Dissections were visible in 4.8% of patients after laser treatment and in 9.3% after balloon angioplasty. Reinterventions during hospitalization were necessary in 0.9% of patients; bypass surgery was performed in 0.2%. CONCLUSIONS: Excimer laser angioplasty with adjunctive balloon angioplasty is a safe and efficient technology to treat in-stent restenoses. These data justify a randomized comparison with balloon angioplasty.

Adult↗

PubMed1986

[Laser angioplasty: effect of laser energy on human coronary arteries].

An experimental study of rationed action of laser emission energy (LEE) on human coronary arteries (autopsy specimens) identified major aspects of LEE interaction with biological tissues of atherosclerotically-affected vessels under "dry" and "wet" conditions. An impulse laser with a 1.06 micron wave-length was used as the LEE source. The results suggest that controlled LEE action on atherosclerotically-affected vessels for recanalization purposes (laser angioplasty) may prove a promising approach to the treatment of cardiovascular occlusions.

Adult↗