Laser-assisted Balloon Angioplasty Research Articles

Long-term outcomes of patients with diabetes mellitus undergoing percutaneous intervention for popliteal and infrapopliteal peripheral arterial disease.

To evaluate the association of diabetes mellitus (DM) with clinical and angiographic characteristics and outcomes of patients with popliteal and infrapopliteal peripheral arterial disease (PAD) undergoing peripheral vascular intervention (PVI). Clinical features and outcomes in patients with DM and popliteal or infrapopliteal PAD undergoing PVI are not well described. Using the data from the laser in popliteal and infrapopliteal stenosis study, we retrospectively examined the association of diabetes with clinical and angiographic characteristics and risk adjusted short- and intermediate term outcomes (all cause death, major adverse events (MAE) [composite of death, ipsilateral major amputation, or repeat revascularization]) in patients with popliteal and infrapopliteal PAD undergoing PVI for critical limb ischemia treated either with laser-assisted balloon angioplasty or balloon angioplasty alone. Of 714 patients, 418 had DM (58.5%). Patients with DM were younger with higher prevalence of history of coronary artery disease, heart failure, end-stage renal disease, and prior contralateral limb amputation compared to those without DM. At 5 years, mean event free survival for all cause mortality (39.9 vs. 45.5 months; P = 0.001), MAE (29.3 vs. 36.8 months; P < 0.001), ipsilateral major amputation (55.3 vs. 57.4 months; P = 0.001), and repeat revascularization (42.0 vs. 45.8 months; P = 0.03) were significantly lower in DM patients. On multivariate analysis, DM was associated with significantly higher all cause mortality (HR = 1.83, 95% CI 1.33-2.52), MAE (HR = 1.73, 95% CI 1.35-2.23), and ipsilateral major amputation (HR = 5.52, 95% CI 1.82-16.71). Among patients with popliteal and infrapopliteal PAD undergoing PVI, DM was associated with higher mortality, major amputations and MAE that was independent of baseline comorbidities. Our data suggested the need for future studies evaluating existing and/or novel therapies to improve the poor long-term outcomes in diabetic patients with popliteal and infrapopliteal PAD.

A retrospective analysis of laser endartherectomy assisted balloon angioplasty for popliteal and infrapopliteal peripheral arterial disease

ObjectivesTo describe our single center experience with the use of laser endartherectomy assisted balloon angioplasty in popliteal and infrapopliteal arterial disease. BackgroundPeripheral arterial disease (PAD) carries significant morbidity to patients. Some patients may have multiple comorbid conditions potentially limiting therapeutic options for PAD. Endovascular interventions are aimed at decreasing arterial disease symptoms, improve wound healing and ultimately limb salvage. There is limited data on below the knee PAD and simultaneous laser endartherectomy use in this anatomic location. MethodsThe cohort comprised 41 patients that underwent laser assisted balloon angioplasty from 2010 to 2013. All patients had popliteal and infrapopliteal arterial disease. Outcomes evaluated were limb salvage and symptom relief 12months following the procedure. A comparison between the patients that underwent amputation and those with limb salvage was also performed. ResultsAll the patients had TASC II (Trans Atlantic Inter-Society Consensus) type D lesions. Most patients reported persistent PAD symptoms by six months, with 17% remaining symptom free by 12months. Affected limb salvage was 69%. Five patients (12%) died and one third of the patients had a new peripheral angiogram. In the repeat angiogram, most patients showed initial target vessel occlusion. No statistically significant differences were found between the patients that preserved their limb to those who underwent amputation. ConclusionsLaser assisted balloon angioplasty use for complex popliteal and infrapopliteal arterial disease is a therapeutic option when limb salvage is the goal. Despite this, symptom recurrence and the need for repeated angiography continue to be high.

Laser in infrapopliteal and popliteal stenosis 2 study (LIPS2): Long-term outcomes of laser-assisted balloon angioplasty versus balloon angioplasty for below knee peripheral arterial disease.

Laser-assisted balloon angioplasty (LABA) has been shown to be more effective in achieving angiographic success for treatment for below knee peripheral artery disease (PAD) compared with balloon angioplasty alone(BA). However, long-term outcomes of LABA compared with BA for popliteal and infrapopliteal PAD are unknown. We evaluated data on 726 patients undergoing LABA (n = 395) and BA (n = 331) for popliteal and infrapopliteal PAD retrospectively at a single center (2007-2012). Outcomes included long-term ipsilateral major limb amputation, revascularization and mortality (median follow-up = 36 months). Baseline features were similar in two groups with the exception of more TASC-D lesions (92.4 vs. 66.5%; P < 0.0001) and chronic total occlusions (86.4 vs. 49.5%; P < 0.0001) in LABA group. Angiographic success was higher in LABA compared with BA (97.7 vs. 89.2%; P < 0.0001). Ipsilateral major limb amputation (4.1 vs. 5.1%, P = 0.48) and repeat revascularization (25.1 vs. 23.3%, P = 0.47) were similar in LABA and BA patients despite unfavorable baseline angiographic characteristics in the former. Compared with BA, death was more frequently in LABA group (35.2 and 26.3%, P = 0.01), a reflection of higher comorbid conditions in this group (adjusted HR 1.05, 95% CI 0.79-1.39). Despite worse baseline angiographic characteristics compared with BA, LABA was associated with higher angiographic success and similar ipsilateral major amputation, repeat revascularization, and long-term mortality. Future randomized clinical trial should evaluate the efficacy of LABA compared with BA (particularly drug-eluting) in improving limb salvage and reducing repeat revascularization in these high-risk PAD patients.

TCT-522 Outcomes of Laser-Assisted Balloon Angioplasty versus Balloon Angioplasty Alone for Below Knee Peripheral Arterial Disease

TCT-522 Outcomes of Laser-Assisted Balloon Angioplasty versus Balloon Angioplasty Alone for Below Knee Peripheral Arterial Disease

Laser in infra-popliteal and popliteal stenosis (LIPS): retrospective review of laser-assisted balloon angioplasty versus balloon angioplasty alone for below knee peripheral arterial disease

Despite the use of laser technology over the last decade, there are limited data to show its procedural and clinical success in infra-popliteal disease. We hypothesized that laser-assisted balloon angioplasty (LABA) is at least similar or better in procedural and peri-procedural outcomes compared to balloon angioplasty (BA) alone, despite adverse lesion characteristics prior to intervention. Retrospective chart and angiogram review of consecutive critical limb ischemia (CLI) patients who underwent endovascular revascularization in the popliteal or infra-popliteal vessels between 2007 and 2012 with LABA or BA alone. Data from 731 patients revealed that baseline demographics were similar in the LABA (n = 398) and BA group (n = 333) with minor exceptions. More patients in the LABA group had TASC-D lesions (92.5 vs. 66.7 %; P < 0.0001) and chronic total occlusions (CTOs) in both vessel 1 (86.4 vs. 49.5 %; P < 0.0001) and vessel 2 (78.6 vs. 47.8 %; P < 0.0001). Multivariate analysis performed using logistic regression after adjusting for confounding factors showed use of LABA was associated with a 7 times greater likelihood of achieving <50 % residual disease compared to BA alone (OR 7.59, P < 0.0001), and a 5 times greater likelihood of improvement in the infra-popliteal lesion severity score than balloon angioplasty alone (OR 4.77, p < 0.0001). LABA is significantly better at achieving angiographic success and improving lesion severity score in spite of adverse lesion characteristics (more TASC-D lesions and CTOs) compared with BA alone. Our findings suggest that the use of LABA is an endovascular approach that is at least as effective and safe or better compared to BA for the treatment of CLI from complex popliteal and infra-popliteal vascular disease.

Excimer laser angioplasty versus balloon angioplasty in functional and total coronary occlusions

Registries of excimer laser coronary angioplasty have reported good results in the treatment of complex coronary artery disease, including total or subtotal coronary occlusions. One hundred three patients (103 lesions) with a functional or total coronary occlusion were included in a randomized trial (Amsterdam-Rotterdam [AMRO] trial, total of 308 patients), 49 patients were allocated to laser angioplasty and 54 patients to balloon angioplasty. The primary clinical end points were death, myocardial infarction, coronary bypass surgery, or repeated coronary angioplasty of the randomized segment during a 6-month follow-up period. The primary angiographic end point was the minimal lumen diameter at follow-up in relation to the baseline value (net gain), as determined by an automated contour-detection algorithm. Laser angioplasty was followed by balloon angioplasty in all procedures. The angiographic success rate was 65% in patients treated with excimer laser-assisted balloon angioplasty compared with 61% in patients treated with balloon angioplasty alone. No deaths occurred. There were no significant differences between the laser angioplasty group and the balloon angioplasty group in the incidence of myocardial infarctions (1 patient vs 3, respectively, p = 0.36), coronary bypass surgery (4 patients vs 2, respectively, p = 0.34), repeat angioplasty (10 patients vs 8, respectively, p = 0.46) or primary clinical end point (15 patients vs 12, respectively, p = 0.34). The net gain in minimal lumen diameter and restenosis rate (>50% diameter stenosis at follow-up) were 0.81 ± 0.74 mm and 66.7%, respectively, in patients treated with laser angioplasty compared with 1.04 ± 0.68 mm and 48.5%, respectively, in patients treated with balloon angioplasty (p = 0.59 and p = 0.15, respectively). Excimer laser-assisted balloon angioplasty demonstrated no benefit over balloon angioplasty with respect to initial and long-term clinical and angiographic outcome in the treatment of patients with functional or total coronary occlusions of >10 mm in length.

No additional benefit from laser in balloon angioplasty of the superficial femoral artery

To evaluate the efficacy of the addition of plaque ablation by hot-tip laser to balloon angioplasty. Prospective randomised clinical trial. Patients with either occlusion orf > 50% diameter stenosis less than 3 cm in length in the superficial femoral artery, and with two or three calf vessel run-off were eligible and randomised to receive either balloon angioplasty alone or with laser assistance. Treatment failure in follow-up was defined as reocclusion or recurrence of greater that 50% stenosis at the site of angioplasty. Ninety limbs (82 patients) were entered into the study. Forty-four patients had mild claudication, 32 more severe symptoms and 6 rest pain or ulceration. More patients with diabetes (5 of 5, p = 0.04, Fisher's exact test) and occlusions (16 of 22, p < 0.05, chi(2)) were randomised to the laser group. Initial technical success was obtained in all lesions. The median duration of follow-up was 1 year. Failure occurred in 40 limbs during follow-up. Three segments, all with initial occlusions and undergoing laser angioplasty re-occluded within 2 days, one requiring immediate thrombectomy. Another 20 limbs underwent further intervention. Overall success (+/- S.D.) (Kaplan-Meier) at 1 year was 67% (+/- 5%) and at 2 years 43% (+/- 7%). Only increased age, initial occlusion, female sex, and not smoking were significantly (p < 0.05, Cox's proportional hazards) associated with failure; on multivariate analysis, age and occlusion were the best independent predictors. There was no significant difference (p > 0.05) in outcome between limbs undergoing laser assisted balloon angioplasty and balloon alone either overall of within the stenosis or occlusion subgroups. This study found no significant benefit was gained by the addition of laser to balloon angioplasty and that the long term success was modest for lesions considered to be suitable for angioplasty.

Holmium laser-assisted coronary angioplasty in acute ischemic syndromes.

Initial studies have shown holmium laser to be effective in ablation of coronary atheroma, and small studies that it may be helpful in ablation of thrombotic stenoses. Therefore, holmium laser-assisted coronary angioplasty was studied in 85 consecutive patients with acute ischemia syndromes. Indications for therapy were acute myocardial infarction (MI) in 7 patients (8%), post-MI ischemic in 32 patients (38%), and crescendo angina pectoris in 46 patients (54%). Coronary morphology characteristics by multivessel angioplasty prognosis group criteria were Type A in 9 (10%), Type B1 in 15 (18%), Type B2 in 44 (52%), Type C in 17 patients (20%). Angiographic evidence of thrombus was seen in 37 (44%) of patients. The laser successfully crossed the total length of the coronary narrowing in 76 patients (89%). Procedure/clinical success was 92% for the total study population, 100% for patients with acute MI, 94% for post-MI ischemia patients, and 89% for patients with crescendo angina. Lesions with and without thrombus had identical procedure success rates. Major complication rate was 3.5%, (deaths 0%, Q-wave MI 0%, and emergent bypass surgery 3.5%). Six-month angiographic restenosis rate (> 50% stenosis) was 45%. Holmium laser-assisted balloon angioplasty appears promising in the treatment of acute ischemic syndromes and thrombotic coronary lesions.

Immediate and late outcome of excimer laser and balloon coronary angioplasty: A quantitative angiographic comparison based on matched lesions

This study sought to compare acute lumen changes and late lumen narrowing during and after excimer laser-assisted balloon angioplasty, measured by quantitative coronary angiography, with the immediate and long-term outcome of balloon angioplasty alone. Although excimer laser coronary angioplasty is used as an adjunct or alternative to balloon angioplasty, limited comparative data exist regarding the immediate and long-term efficacy of excimer laser-assisted balloon angioplasty versus balloon angioplasty alone. A series of 53 lesions in 47 consecutive patients successfully treated with excimer laser-assisted balloon angioplasty were individually matched after completion of 6-month follow-up angiography with 53 successfully treated balloon angioplasty lesions according to vessel location, preprocedural minimal lumen diameter and reference diameter. Immediate and long-term angiographic results were assessed by an automated lumen contour detection algorithm. Before intervention in the laser and balloon angioplasty groups, respectively, minimal lumen diameter (mean +/- SD) was 0.73 +/- 0.47 and 0.74 +/- 0.46 mm, and reference diameter was 2.71 +/- 0.42 and 2.72 +/- 0.41 mm. Laser angioplasty was followed by adjunctive balloon dilation in 50 lesions. Mean balloon diameter at maximal inflation was similar in both treatment groups (2.61 +/- 0.32 and 2.65 +/- 0.38 mm, respectively), resulting in similar minimal lumen diameters after intervention of 1.77 +/- 0.41 and 1.78 +/- 0.34 mm, respectively. At follow-up angiography, minimal lumen diameter after excimer laser-assisted balloon angioplasty was 1.17 +/- 0.63 mm, and that after balloon angioplasty alone was 1.46 +/- 0.67 mm (p = 0.02). The angiographic restenosis rates at follow-up using the 50% diameter stenosis cutoff criterion were 57% and 34%, respectively (p = 0.02). Quantitative angiographic analysis of a matched group of 106 successfully treated coronary lesions showed a similar immediate outcome but reduced long-term efficacy of excimer laser-assisted balloon angioplasty compared with that after balloon angioplasty alone.

Nd:Yag laser-assisted balloon angioplasty of superficial femoral artery occlusions in a diabetic population

Laser-assisted balloon angioplasty (LABA), has potential as a treatment modality for re-establishing flow in occluded arterial segments. The objective of this retrospective review is to summarize the results of LABA of totally occluded superficial femoral arteries in 33 limbs among 32 diabetic patients. Indications for vascular intervention in this population included disabling claudication in 15 (45.6%), rest pain in 9 (27.2%), and tissue loss in 9 (27.2%) limbs. The review of preoperative arteriograms allowed for the division of limbs into three groups by occlusion length as follows; less than 5 cm, between 5 and 10 cm, and greater than 10 cm. Overall initial success rate was 21 of 33 (63.6%). Nine of ten (90%) occlusions less than 5 cm in length; six of nine (66.7%) occlusions between 5 and 10 cm in length; and six of 14 (42.9%) lesions greater than 10 cm in length were initially successfully recanalized. Overall cumulative patency rate at 1 year was 22.5%. For occlusion lengths less than 5 cm, cumulative patency rates at 1 year and 2 years were 66.4% and 33.2%, respectively. All lesions greater than 5 cm that were initially recanalized, uniformly re-occluded by 1 year. The number of complications (vessel perforation or dissection) increased as lesion length increased. The theoretic advantages of laser energy's ability to recanalize occlusive lesions are lost when coupled with the balloon angioplasty technique, especially in diabetics. Laser-assisted balloon angioplasty in its present form should be considered an investigational tool requiring further technologic refinements and controlled clinical trials.

Femoropopliteal artery recanalization: factors affecting clinical outcome of conventional and laser-assisted balloon angioplasty.

The clinical efficacy of 44 successful conventional and laser-assisted recanalizations of the femoropopliteal artery was assessed in a noncomparative study by the life-table method. Laser-assisted angioplasty using continuous laser and a sapphire probe was performed to achieve primary recanalization in femoral artery occlusions when conventional guidewire recanalization had already failed. Nineteen of the patients underwent a conventional recanalization (PTA; mean length of occlusion 4.4 +/- 4.1 cm), and 25 underwent percutaneous laser-assisted angioplasty (PLA; mean length of occlusion 10.1 +/- 6.7 cm). There was no statistical relation between the preprocedure Fontaine classification and the success rate in the PTA cases (p = 0.25), whereas there was a statistical relation in the PLA cases: The success rate in patients preprocedurally classified as Fontaine II was better than in those classified as Fontaine III/IV (p = 0.05). After a 3-year follow-up the patency rate in the patients with the PTA recanalizations was 37% and that in those with the PLA procedure was 53%. This difference was not statistically significant (p = 0.47). It is concluded that the laser should remain an investigational device.

Quantitative angiographic comparison of elastic recoil after coronary excimer laser-assisted balloon angioplasty and balloon angioplasty alone

Objectives. Coronary lumen changes during and after excimer laser-assisted balloon angioplasty were measured by quantitative coronary angiography, and the results were compared with the effects of balloon angioplasty alone.Background. Reduction of atherosclerotic tissue mass by laser ablation in the treatment of coronary artery disease may be more effective in enlarging the lumen than balloon angioplasty alone.Methods. A series of 57 consecutive coronary lesions successfully treated by xenon chloride excimer laser-assisted balloon angioplasty were individually matched with 57 coronary artery lesions successfully treated by balloon angioplasty alone. The following variables were measured by quantitative coronary analysis: 1) ablation by laser, 2) stretch by balloon dilation, 3) elastic recoil, and 4) acute gain.Results. Matching by stenosis location, reference diameter and minimal lumen diameter resulted in two comparable groups of 57 lesions with identical baseline stenosis characteristics. Minimal lumen diameter before excimer laser-assisted balloon angioplasty and balloon angioplasty alone were (mean ± SD) 0.73 ± 0.44 and 0.74 ± 0.43 mm, respectively. Laser ablation significantly improved minimal lumen diameter by 0.56 ± 0.44 mm before adjunctive balloon dilation. In both treatment groups, similar-sized balloon catheters (2.59 ± 0.35 and 2.56 ± 0.40 mm, respectively) were used. After laser-assisted balloon angioplasty, elastic recoil was 0.84 ± 0.30 mm (32% of balloon size), which was identical to that after balloon angioplasty alone, namely, 0.82 ± 0.32 mm (32%). Consequently, both interventions resulted in similar acute gains of 1.02 ± 0.52 and 1.00 ± 0.56 mm, respectively. Minimal lumen diameter after intervention was equal in both groups: 1.75 ± 0.35 and 1.75 ± 0.34 mm, respectively. The statistical power of this study in which a 25% difference in elastic recoil (0.2 mm) between groups was considered clinically important was 95%.Conclusions. In matched groups of successfully treated coronary lesions, xenon chloride excimer laser ablation did not reduce immediate elastic recoil after adjunctive balloon dilation or improve the final angiographic outcome compared with balloon angioplasty alone using similar-sized balloon catheters.

Laser angioplasty: Useful tool or interesting toy?

Laser angioplasty, or more accurately, laser assisted balloon angioplasty is a recent development in the treatment of arterial occlusion, the first case being described in 1984 (1). Since that time physicians involved in the treatment of arterial occlusion have witnessed a ‘boom and bust’ in laser sales and cases performed. This article looks at the development of this technique and analyses why the early promise of laser angioplasty has failed to be fulfilled.

Comparative long-term results of laser-assisted balloon angioplasty and atherectomy in the treatment of peripheral vascular disease

Early results of laser-assisted balloon angioplasty (LABA) and peripheral directional atherectomy (PDA) are encouraging. The true value of these procedures has remained in doubt, however, because of the absence of data on long-term objective patency rates. From August 1988 through October 1993, LABA and PDA were performed on 151 limbs of 124 patients. Presenting symptoms were mild-to-severe claudication in 128 limbs (63 LABA, 65 PDA) and rest pain or necrosis in 23 (7 LABA, 16 PDA). Seventy-seven percent of the atherosclerotic lesions were localized in the iliofemoral tract (77% LABA, 76% PDA). Seventy limbs were treated with LABA and 81 with PDA. Initial hemodynamic and arteriographic success was achieved in 46 LABA limbs (66%) and 75 PDA limbs (93%) (P < 0.002). Mean follow-up was 16 +/- 2 months after LABA and 18 +/- 1 months after PDA. During this time, 32 failures were recorded in limbs treated with LABA, and 29 in limbs treated with PDA. The patency rate at 40 months was 23% in the LABA group and 45% in the PDA group (P < 0.005). Patency rates were not affected by the length or site of the arterial lesion or the runoff score. PDA had a better long-term patency rate than LABA, but long-term results were dismal with both techniques. PDA appears to have a limited role and LABA no role in the treatment of lower extremity occlusive disease.

Angiographic follow-up after laser-assisted balloon angioplasty

Purpose: The purpose of this study was to obtain angiographic documentation of patency and recurrence rates after laser-assisted balloon angioplasty.Methods: A prospective assessment of laser-assisted balloon angioplasty (LABA) was performed in 35 limbs of 33 patients with femoral popliteal atherosclerotic disease. There were 21 male and 12 female patients with a mean age of 60.6 years. Indications were intermittent claudication in 19, rest pain in nine, and ischemic ulcer/gangrene in seven limbs. There were 23 totally occluded (mean length 6 ± 3.8 cm) and 12 stenotic arteries. LABA was achieved with a pulsed Nd: YAG laser with 10 to 25 W and a 2.23mm sapphire probe, followed by balloon dilatation in all but four limbs.Results: Immediate technical success (≤50% residual stenosis) was achieved in 27 (77%) of 35 limbs. Mean ankle/brachial index improved from 0.49 to 0.80 (p < 0.05). Major complications included three perforations, three dissections, and two emboli. Two additional limbs required operation at less than 30 days for a 30-day patency rate of 71.4%. Long-term clinical and noninvasive follow-up ranged from 1 to 55 months (mean 17.68 months). Twenty-nine angiograms were obtained from 3 to 49 months after LABA. Nineteen limbs underwent at least one angiogram, seven underwent two, and three limbs underwent three angiograms. Eleven of the 19 limbs showed evidence of restenosis greater than 50%, all within 12 months. The cumulative patency rate was 71.5% at 1 month, 39.7% at 6 months, and 31.3% at 12, 24, and 36 months.Conclusions: LABA with the Nd:YAG laser has a 30-day success rate of 71.4%. Angiographic follow-up demonstrates a high incidence of restenosis (>50%), usually within 12 months. Approximately 50% of limbs eventually required reintervention within 1 year. In view of the disappointing early results, the use of LABA must remain strictly investigational.

Direct holmium laser-assisted balloon angioplasty in acute myocardial infarction

The holmium laser (Thulium-Holmium-Chromium: yttrium-aluminum garnet [YAG]laser) system was recently introduced for the treatment of atherosclerotic peripheral arterial and coronary artery lesions. 1–6 This pulsed mid-infrared laser (2.1 μm) ablates atherosclerotic tissue without significant thermal damage to adjacent tissue. 2,3,6,7 This study was designed to test the hypothesis that delivery characteristics of and tissue sensitivities to holmium laser energy make it a feasible treatment option in patients with acute myocardial infarction, with thrombosis and atherosclerotic plaque. In this report, we provide data on the first 3 cases of direct laserassisted balloon angioplasty during an acute myocardial infarction.

Vascular Applications of Lasers

There have been major advances in laser technology and in our understanding of the effects of laser energy on blood vessels. This, in turn, has led to the many clinical applications of lasers in patients with vascular disease. The clinical results of laser endarterectomy, laser angioplasty, laser-assisted balloon angioplasty, laser-assisted vascular anastomoses, and the future of lasers in cardiovascular disease are discussed.

Results and follow-up after percutaneous pulsed laser—assisted balloon angioplasty guided by spectroscopy: Geschwind HJ, Aptecar E, Boussignac G, et al. Circulation 1991;83:787–796

Results and follow-up after percutaneous pulsed laser—assisted balloon angioplasty guided by spectroscopy: Geschwind HJ, Aptecar E, Boussignac G, et al. Circulation 1991;83:787–796

In Vitro and Clinical Feasibility Study with an Over-the-Wire Delivery System for Pulsed Dye Laser Angioplasty

The suitability of a pulsed dye laser (504 nm) in experimental and clinical angioplasty was investigated. In an experimental study, the ablation thresholds were 3 J/cm2 +/- 8 (mean +/- standard deviation) for fibrofatty plaque and 25 J/cm2 for calcified tissues under saline. At a radiant exposure of 10 J/cm2 the etch rates were 1.7 microns per pulse +/- 0.3 for media, 2.8 microns/pulse +/- 0.4 for normal intima, and 3.9 microns/pulse +/- 1.1 for fibrofatty plaque (P less than .05). Pressure wave effects with a separation of tissue layers were predominantly localized at the internal elastic lamina. Thermal injury with vacuolations extended 15 microns +/- 6 into adjacent tissue. For clinical study, laser-assisted balloon angioplasty was performed in 10 patients (64 years +/- 14) with occlusions of peripheral arteries using a 9-F multifiber ring catheter. Lesion length ranged from 2 to 12 cm (mean, 7 cm). Laser angioplasty with an 80 mJ/pulse decreased the mean stenosis from 100% to 58% +/- 12% (P less than .005). The ankle-brachial index rose from a median of 0.48 to 0.88 (P less than .001). In 33% of patients, there were subintimal dissections after laser angioplasty. After a mean follow-up of 10.2 months, the overall clinical success was 70% with a primary patency of 78%. The over-the-wire approach with a pulsed dye laser may constitute a safe and feasible tool in laser angioplasty.

Platelet accumulation after laser angioplasty--a scintigraphic assessment.

Indium 111-labeled platelet scintigraphy was performed to evaluate platelet deposition in response to different levels of Nd:YAG laser/thermal energy. A dose-related increase in platelet deposition was observed. In clinical studies after laser-assisted balloon angioplasty, intense platelet deposition was observed in 2 patients who subsequently developed clinical arterial thrombosis. The pathogenesis of reocclusion appears, however, to be more complicated and ill understood. The authors suggest further extensive studies incorporating several parameters in the evaluation of the pathogenic factors involved in reocclusion after laser angioplasty. Such studies should also consider the role of arterial injury produced by the balloon catheter after laser-assisted balloon angioplasty.