Excimer Laser Angioplasty Research Articles

Coronary artery perforation during excimer laser coronary angioplasty

Objectives. The aim of this study was to analyze the risk of vessel perforation during excimer laser angioplasty.Background. Vessel perforation is a serious complication of angioplasty.Methods. A total of 764 patients had 858 stenoses treated with excimer laser angioplasty. Laser catheters had a diameter of 1.4, 1.7 or 2 mm. Laser energy was delivered in pulses of 135 ns, at a frequency of 25 s−1and at a fluence of 30 to 60 mJ/mm2. Follow-up angiography was requested for all patients who did not require emergency bypass surgery.Results. In the 764 consecutive patients treated with excimer laser coronary angioplasty, vessel perforation occurred in 23 patients (3%). Nine patients had a major complication resulting directly from vessel perforation (cardiac tamponade, myocardial infarction or need for bypass surgery) and 14 had no clinical complications after successful sealing of the puncture site. No patient with a perforation died. Multivariate analysis showed that bifurcation lesions (odds ratio [OR] = 3.5; p = 0.049), diabetes mellitus (OR = 3.15; p = 0.029) and female gender (OR = 2.86; p = 0.013) were associated with an increased risk of vessel perforation. Lesions >;10 mm in length (OR = 0.45; p = 0.206), calcified stenoses (OR = 0.26; p = 0.088) and saphenous vein graft lesions (OR = 0.50; p = 0.295) were not at increased risk. Vessel perforation was seen in 10 (8.3%) of 120 lesions in which the laser catheter was equivalent in diameter to the target vessel (≤0.5 mm smaller in size) but in only 8 (1.5%) of 525 lesions in which the laser catheter was >;1 mm smaller than the target vessel (p = 0.001).Conclusions. Most lesions thought to be suitable for excimer laser treatment are not at increased risk of perforation. The complication may be avoided by improved patient and laser catheter size selection.

Reliability of quantitative coronary angiography of the target lesion immediately and 1 day after coronary balloon and excimer laser angioplasty

Objectives. This prospective trial was performed to evaluate the impact of the morphologic complications of angioplasty on the reliability and results of quantitative angiographic assessment of the residual stenosis.Background. Postintervention quantitative coronary analysis is limited by a variety of such complications.Methods. In 199 patients undergoing an early control angiographic study within 24 h after coronary balloon or excimer laser angioplasty (24-h study), detailed quantitative angiographic measurements were performed on the target lesion immediately after intervention and at the 24-h study. Reproducibility of quantitative arteriography was determined by repeat measurements on the same angiogram.Results. Intraobserver/interobserver variability was significantly higher (p < 0.0001/p < 0.03) for the postintervention angiogram than for the 24-h angiogram. Patients were classified into three subgroups with respect to the occurrence of angiographic complications or chest pain after intervention. In patients with angiographic complications after balloon angioplasty alone/ stand-alone laser angioplasty/laser angioplasty with adjunctive balloon dilation, a significant difference in mean minimal lumen diameter (p = 0.0001/p = 0.03/p = 0.035) was observed between the immediate postintervention and 24-h angiogram. In patients without angiographic complications or patients with recurrent chest pain undergoing balloon angioplasty, stand-alone or adjunctive laser angioplasty, mean minimal lumen diameter remained nearly unchanged (p = NS).Conclusions. Angiographic measurements of the target lesion immediately after angioplasty were significantly less reliable than measurements obtained at 24 h after angioplasty in patients with angiographic complications. The occurrence of postintervention vascularcomplications was associated with significant early lesion changes between the immediate postangioplasty and the 24-h angiogram.

Initial experience with excimer laser angioplasty for coronary ostial stenoses.

The excimer laser has several potential advantages over conventional balloon angioplasty in the management of stenoses of the native coronary arteries and of the ostia of saphenous vein grafts. Its use in nine patients, eight of whom were classed as high risk, is described. Four lesions involved the ostia of saphenous vein grafts, three of protected left main stems, and two of native right coronary arteries. Stand alone laser was used in seven cases and laser with additional balloon angioplasty was used in two vein graft stenoses. Acute laser success was achieved in all cases, with a mean reduction of stenosis from 82% to 34% after laser alone and to 28% when balloon angioplasty was used as well. One patient died during laser angioplasty to a non-ostial lesion (procedural success rate 89%) and a second died ten weeks after the procedure. In one patient recurrent angina developed (clinical recurrence rate 25%) and restenosis was confirmed on angiography. Follow up angiography was also performed on the other six surviving patients, all of whom were symptom free and none of whom showed evidence of significant restenosis (restenosis rate 14%). With a mean follow up of 19.7 months the overall success rate was 67%.

Immunohistochemical analysis of a human coronary artery exposed to excimer laser angioplasty in vivo: Evidence for release of fibroblast growth factor at the site of injury

Immunohistochemical analysis of a human coronary artery exposed to excimer laser angioplasty in vivo: Evidence for release of fibroblast growth factor at the site of injury

Excimer and holmium yttrium aluminum garnet laser coronary angioplasty

Recently access to the coronary arteries became available to laser angioplasty because of a new technique utilizes a pulsed laser source and multifiber, “over-the-wire” guided catheters. The aim of this study was to evaluate the early and long-term results and the side effects of coronary angioplasty with an excimer or a Ho-YAG laser. Forty consecutive patients were treated with the Ho-YAG laser (group I) and 46 consecutive patients were treated with the excimer laser (group II). The primary laser angioplasty success rate was 55% and 72% (NS) for groups I and II, respectively. This success rate was highest in saphenous vein grafts. It was similar in calcified and noncalcified lesions and in total occlusions and stenoses. It tended to be lower in long lesions than in short ones (40% vs 60%; p < 0.05 and 44% vs 78%; NS for groups I and II, respectively). Laser standalone therapy was performed in 5% of patients in group I compared with 22% in group II ( p < 0.05). Failures were due to the inability of the laser catheter tip to reach the lesion, to cross the obstruction, or to obtain a significant reduction in stenosis. They were more frequent in patients in group I than in those in group II (45% vs 28%). There were no deaths, no myocardial infarctions, and no need for emergency coronary artery bypass grafting because most patients had total occlusions or a well-protected coronary artery. Complications included acute closure in 8% of patients in group I and in 17% of patients in group II and spasm in 10% and 13% of patients in groups I and II, respectively. Dissection occurred more frequently in patients in group II than in those in group I (28% vs 7%; p < 0.04). The angiographic patency rate at 6-month follow-up was 33% and 29% for patients groups I and II, respectively. Multifiber, wire-guided catheters provide easy access to the coronary arteries. Excimer laser angioplasty is effective but induces a high rate of dissections. Technical improvements are required to ablate more tissue to possibly reduce the restenosis rate. Further studies are needed to elucidate the mechanism of side effects and to reduce the restenosis rate.

Percutaneous angioscopic evaluation of luminal changes induced by excimer laser angioplasty

Angioscopy has been shown to provide more detailed information on lesion morphology before and after interventional procedures than angiography. Therefore to evaluate the effects of laser angioplasty, angioscopy was performed in five patients with peripheral or coronary vascular disease who underwent excimer laser angioplasty. The excimer laser was operated at 308 nm, 135 nsec, 25 Hz, and 40 to 60 mjoules/mm 2 and was coupled into multifiber wire-guided catheters of 1.4 to 2.0 mm diameter for coronary lesions and into catheters of 2.2 mm diameter for peripheral lesions. There were three coronary (one left anterior descending, one circumflex, one right coronary artery) and two peripheral (one common iliac artery, one superficial femoral artery) lesions. Angioscopy was successfully performed before and after laser ablation without any complications in all five lesions. The characteristics of angioscopic findings after excimer laser angioplasty consisted of flaps, fractures of plaques, and abundant tissue remnants. There was no apparent thermal injury. Recanalized channels were small and irregular. These results indicate that (1) angioscopy is effective and safe for evaluation of lesion morphology after laser angioplasty; (2) laser ablation does not result in thermal injury; and (3) irregular channels after recanalization and abundant tissue remnants may explain the suboptimal results after laser angioplasty.

Clinical success, complications and restenosis rates with excimer laser coronary angioplasty

The role of excimer laser angioplasty in treating complex coronary artery disease remains uncertain. A randomized trial comparing this new technology with balloon angioplasty cannot be designed until systematic analysis identifies the lesion types that are likely to benefit from treatment with excimer laser angioplasty. In a cohort of 764 patients who had 858 coronary stenoses treated with excimer laser-facilitated angioplasty, relative risk analysis was used to examine acute success, complications and restenosis rates, and the results were compared with those of balloon angioplasty to identify the lesion types that show the greatest benefit with the new treatment. Clinical success was achieved in 657 patients (86%), as indicated by ≤50% residual stenosis and no in-hospital complication. A major in-hospital complication (death, bypass surgery, or Q-wave or non-Q-wave myocardial infarction) occurred in 58 patients (7.6%). Follow-up angiography was obtained in 70% of eligible patients. Combining angiographic and noninvasive restenosis rates yielded an overall restenosis rate of 46%. Relative risk analysis showed that major complications occurred frequently in lesions at an arterial bifurcation (odds ratio [OR] 5.96 [2.76, 12.6]; p = 0.001). However, certain complex lesions that are difficult to treat with balloon angioplasty (saphenous vein graft lesions, lesions >10 mm, ostial lesions, calcified stenoses, total occlusions and unsuccessful balloon dilatations), analyzed together as a group, had lower complication rates by univariate (OR 0.59 [0.35, 1.00]; p = 0.051) and multivariate logistic regression (p = 0.006) analyses. Restenosis rates were higher for lesions >10 mm in length (OR 1.28 [1.02, 2.29]; p = 0.014) and for those treated with laser alone (OR 1.69 [1.02, 2.88]; p = 0.049). In conclusion, the use of excimer laser-facilitated angioplasty to treat many lesion types will be limited by significant restenosis, despite acceptable initial clinical results. Favorable success rates with this new technology were found for a group of 6 lesions that comprise the “alpha class” (saphenous vein graft lesions, long lesions, ostial lesions, calcified stenoses, total occlusions and unsuccessful balloon dilatations). Direct, controlled comparison with other interventional technologies will define the ultimate role of the excimer laser angioplasty procedure.

Success with coronary angioplasty as seen at demonstrations of procedure

To assess the real-life results of coronary angioplasty, unidentified participants made notes on 104 cases demonstrated live at twelve international angioplasty courses in 1991. The initially planned procedure was successful in 73% with crossover to another device in 20% for an ultimate success rate of 93%. Interventions lasted an hour on average and two devices on average were used per artery tackled. Rates of success and of complication necessitating reintervention were, for balloon angioplasty (57 cases) 81% and 19%, for directional atherectomy (16 cases) 75% and 0%, for the Rotablator (12 cases) 42% and 42%, for stent implantation (10 cases) 100% and 0%, for excimer laser angioplasty (6 cases) 17% and 33%, and for Rotacs recanalisation (3 cases) 67% and 0%, respectively. The complications were occlusions (threatened, acute, or delayed) and they were usually treated by balloon angioplasty or a stent. No death or myocardial infarction was reported. The observer attending the demonstration tended to take a less favourable view of the outcome than the clinician doing the procedure and in general the results of coronary angioplasty seemed inferior to those reported in journals. Interventions done before an audience will be unusually stressful but this will be outweighed by the fact that difficult cases with a low probability of success are rarely tackled during live courses. This survey suggests that conventional balloon angioplasty, complemented by stent implantation in selected cases, is the treatment of choice.

Percutaneous Laser Angioplasty of Peripheral Vessels: Primary Success and Follow-up Results

Excimer laser angioplasty was attempted in 59 patients (43 men, 16 women, mean age sixty-three ± eight years, range thirty-nine to seventy-seven years), affected by peripheral vascular disease. Forty-nine patients had a total occlusion of one superficial femoral artery, 3 of one iliac artery, and 1 of one popliteal artery; 6 patients showed a subocclusive stenosis of a superficial femoral artery. Occlusive and subocclusive stenoses were classified by length: &lt; 10 cm (39 cases), &gt; 10 cm (20 cases). A commercial excimer laser was used at the xenon-chloride wavelength of 308 nm. Successful recanalization was obtained in 53 of 59 patients (90%). Hemodynamic improvement was confirmed by a significant increase of the ankle/ brachial systolic pressure index (from 0.60 ± 0.17 to 0.79 ± 0.20, p &lt; 0.005). The success rate was higher for lesions &lt; 10 cm in length. Early reocclusion was observed in 7 patients and was associated with poor runoff. The cumulative patency rate was 81 % at one month, 67% at six months, and 51 % at one year.

Comparison of pulsed laser-assisted angioplasty and balloon angioplasty in femoropopliteal artery occlusions.

The authors performed a prospective, comparative study of 96 patients (age, 41-87 years) with femoropopliteal artery occlusions. Laser-assisted angioplasty was performed in 64 patients with 9- and 7-F over-the-wire multifiber catheters. Supplemental balloon dilation was performed after laser angioplasty. Thirty-two patients underwent excimer laser angioplasty (ELA), and 32 underwent pulsed dye laser angioplasty (DLA). The remaining 32 patients underwent conventional balloon angioplasty (BA). The length of occlusions was 3-10 cm (mean, 6.3 cm). Lesion characteristics in the three patient groups were similar. Technical success rates were 84% for ELA, 78% for pulsed DLA, and 81% for conventional BA. The 1-year clinical success rate was 69% (22 of 32 patients) in the ELA group, 63% (20 of 32 patients) in the pulsed DLA group, and 66% (21 of 32 patients) in the BA group (differences were not significant). Laser-assisted angioplasty with multifiber catheters in femoropopliteal artery occlusions did not help improve the technical success rate and 1-year clinical success rate when compared with those of conventional BA.

Excimer laser angioplasty in the atherosclerotic rabbit: Comparison with balloon angioplasty

The early and late results of excimer laser angioplasty and balloon angioplasty were compared in atherosclerotic rabbit iliac arteries. Immediately after laser angioplasty ( n = 13) with a bare 600 μm fiber, there was a 33% increase in angiographically measured minimum lumen diameter; after balloon angioplasty ( n = 12), there was a 53% increase. Restenosis (defined as loss of at least 50% of the gain achieved by angioplasty) occurred in none of six laser-treated rabbits studied 1 month later, compared with four of six balloon-treated rabbits ( p = 0.06). Planimetric measurements of cross sections of the arterial wall 1 month after angioplasty showed less intimal and medial tissue in laser-treated (1.8 ± 0.2 mm 2) than in the balloon-treated rabbits (3.0 ± 0.4 mm 2; p < 0.05). Typical thermal effects were absent on microscopic examination of laser angioplasty sites. It is concluded that in this animal model, excimer laser irradiation results in an immediate increase in lumen diameter comparable with balloon angioplasty, but is associated with less residual atheromatous tissue than balloon angioplasty and a trend toward a lower rate of restenosis.

Excimer laser-facilitated coronary angioplasty. Relative risk analysis of acute and follow-up results in 200 patients.

Excimer laser coronary angioplasty has been reported to be a promising treatment for complex coronary artery disease. The purpose of this study was to define the predictors of acute success and restenosis after this experimental intervention. A cohort of 200 consecutive patients had a minimum of 6 months of follow-up evaluation after treatment of 215 coronary stenoses that were carefully selected for excimer laser coronary angioplasty. At the time of the initial procedure, the laser catheter alone produced a residual stenosis of less than or equal to 50% at 119 of 215 lesions (55.4%). For complete dilatation, 87.9% of the lesions required adjunctive balloon angioplasty. Clinical success was achieved in 183 of the 200 patients (91.5%), as indicated by a reduction by at least 20% of the narrowing of the vessel diameter, less than or equal to 50% residual stenosis, and no in-hospital complication. Complications included abrupt closure (5.0%), myocardial infarction (3.5%), bypass surgery (3.0%), perforation (2.0%), and death (0.0%). Logistic regression analysis showed that lesions at vessel bifurcations (success rate, 66%; adjusted odds ratio [OR] = 0.16; p = 0.002) or in tortuous vessels (success rate, 82%; OR = 0.48; p = 0.004) were associated with decreased clinical success. However, acceptable success rates were achieved in patients with lesions in saphenous vein grafts more than 3 years old (success rate, 94%; OR = 1.40; p = 0.75), in ostial lesions (success rate, 100%; OR = 3.36; p = 0.43), and in lesions longer than 10 mm (success rate, 93.5%; OR = 1.50; p = 0.39). Clinical follow-up was available in 197 of the 200 patients (98.5%) a mean of 5.9 +/- 1.9 months after angioplasty, at which time 31.0% of patients had developed symptoms or evidence of ischemia. No patient died during the study. Follow-up angiography was obtained in 83.1% of eligible patients after a mean [+/- SD] of 5.2 +/- 2.0 months. Angiographic restenosis, defined by greater than 50% stenosis, appeared at 78 of 164 lesions (47.6%). By logistic regression analysis, only lesions in saphenous vein grafts were associated with a decreased rate of restenosis (restenosis rate, 20%; OR = 0.18; p = 0.01). This analysis, which defines the profile of risk for excimer laser angioplasty, provides a sound basis for rigorous comparison of adjunctive excimer laser with balloon angioplasty for ostial narrowings, long lesions, and saphenous vein graft stenoses.

Origin of arterial wall dissections induced by pulsed excimer and mid-infrared laser ablation in the pig

To study adjacent tissue damage after delivery of holmium, thulium and excimer laser pulses, porcine thoracic aortas were irradiated in vivo. After 3 days, microscopic analysis of 67 craters produced by all three lasers demonstrated large dissections extending from the craters. The mean diameter of the dissections was smaller for excimer-induced craters (1.38 ± 0.42 mm; n = 22) than for holmium-induced (2.7 ± 0.87 mm; n = 22) and thulium-induced (2.37 ± 0.42 mm; n = 14) craters (p < 0.01 vs. mid-infrared dissections). In addition, microscopic analysis demonstrated necrosis adjacent to the crater. The lateral necrotic zones of the thulium-induced craters were smaller than the holmium- and excimer-induced necrotic zones (p < 0.01).To identify the origin of the excessive tissue tearing, laser-saline and laser-tissue interaction were compared in vitro by time-resoived flash photography, in saline solution, the midinfrared lasers showed bubble formation on a microsecond time scale. The excimer laser produced similar bubbles in the vicinity of tissue. For all three lasers, elevation of the tissue surface was shown during in vitro ablation. Dimension (diameter up to 4 mm) and time course (rise time of 100 to 300 μs) of bubble formation and tissue elevation were strikingly similar.Thus, tissue dissections are caused by the expansion of a vapor bubble within the target tissue. Coronary dissections after excimer and mid-infrared laser angioplasty might be related to the forceful bubble expansion.

In vivo assessment of vascular pathology resulting from laser irradiation. Analysis of 23 patients studied by directional atherectomy immediately after laser angioplasty.

The pathological consequences of cardiovascular laser irradiation have been studied extensively in vitro. Previous in vivo studies of laser-induced injury have included analyses of acute and/or chronic findings in experimental animals. Little information, however, is available regarding the acute effects of laser irradiation of human vascular tissues in vivo. To determine the acute pathology resulting from laser irradiation of human vascular tissue in vivo, specimens retrieved from 23 patients by directional atherectomy immediately after laser angioplasty (19 peripheral and four coronary) were examined by light microscopy. Of the 23 patients, three (13.0%) were treated with a metal-capped ("hot-tip") fiber coupled to a continuous-wave neodymium:yttrium-aluminum-garnet (Nd:YAG) laser using up to 18 W power and 18-305 seconds of cumulative exposure time; in all three patients (100%), thermal injury, including frank charring several cell layers thick, was seen along the luminal borders of the atherectomy specimen. In eight of the 23 patients (34.5%), laser angioplasty was performed using a 250-microseconds holmium:YAG laser at fluences up to 2,300 mJ/mm2, a repetition rate of 5 Hz, and 25-200 seconds of cumulative exposure; in seven of eight patients (85.5%), the atherectomy specimen showed signs of vacuolar injury consisting of central and satellite Alcian-blue-negative vacuoles. In two patients (25.0%), there was a "smudged" or "shredded" edge, whereas in one patient, frank signs of thermal injury were observed. Finally, in 12 of the 23 patients (52.2%), laser angioplasty was performed using a 120-nsec excimer laser at fluences up to 60 mJ/mm2, a repetition rate of 25 Hz, and a cumulative exposure time of 21-315 seconds. Pathological findings among these 12 patients were limited to nine patients (75%) in whom a weakly basophilic, smudged, and/or shredded appearance approximately one cell layer thick was observed along the luminal border of the atherectomy specimen and two patients (16.7%) with small foci of vacuolar injury. None of the atherectomy specimens retrieved after excimer laser angioplasty disclosed signs of thermal injury. These findings document that acute pathological alterations resulting from in vivo laser angioplasty are variable, depending on the laser source used, and are similar to that predicted by experimental studies performed previously in vitro. The prognostic implications of these varying pathological features remain to be clarified.

Restenosis after excimer laser angioplasty of coronary stenoses and chronic total occlusions

In an open clinical study, a xenon-chloride excimer laser was used for angioplasty of coronary stenoses (n = 48) and chronic total occlusions (n = 56) in 104 patients. Multifiber catheters (4.0F to 5.5F) transmitted 37 to 120 mjoules/mm 2 of fiber surface. Excimer laser angioplasty was successful in 43 patients with a stenosis (89%), followed by percutaneous transluminal coronary angioplasty in 21 patients (49%) to reduce the stenosis to less than 50% luminal narrowing. In 39 patients (70%) with a chronic occlusion (age 1 to 14 months), recanalization by means of excimer laser angioplasty was successful, with subsequent percutaneous transluminal coronary angioplasty performed in 23 patients. Major complications included one perforation, one acute occlusion, and two severe dissections. Six-month angiographic follow-up examinations after successful angioplasty were completed in 40 patients (98%) with stenoses and 34 (94%) with occlusions. Restenosis (> 20% decrease in luminal diameter) occurred in 13 patients (33%) with stenoses and in 16 patients (47%) after angioplasty of a chronic occlusion. These long-term results indicate that restenosis after excimer laser angioplasty of coronary stenoses and chronic total occlusions is similar to reported results of conventional balloon angioplasty.

Effect of force on ablation depth for a XeCl excimer laser beam delivered by an optical fiber in contact with arterial tissue under saline.

The effect of force applied to a 430 micron single fiber, delivering 60 pulses of 308 nm XeCl laser radiation at 20 Hz, on the ablation depth in porcine aortic tissue under saline has been investigated. Energy densities of 8, 15, 25, 28, 31, 37, and 45 mJ/mm2 were used. Force was applied by adding weights from 0 to 10 grams to the fiber. The fiber penetration was monitored by means of a position transducer. At 0 grams, the ablation depth increased linearly with incident energy density, but the fiber did not penetrate the tissue; with any weight added, the fiber penetrated the tissue at energy densities above 15 mJ/mm2. The fiber did not penetrate during the first several pulses, possibly due to gas trapped under the fiber. After these first pulses, a smooth linear advancement of the fiber began, which lasted until the pulse train stopped. The ablation depth increased with increasing energy densities and weights. This effect was largest above 25 mJ/mm2 where the ablation efficiencies (unit mm3/J), with weights added to the fiber, were substantially larger than values found in 308 nm ablation experiments described in the literature, which were conducted with either a focused laser beam or a fiber without additional force. The results imply that in 308 nm excimer laser angioplasty, force must be applied to the beam delivery catheter for efficient recanalization, and that experiments performed with a focused beam or without actual penetration of the fiber do not represent the situation encountered in excimer laser angioplasty.

極限ファイバースコープに向けて

Objective: Angioscopy has proved to provide more detailed information on lesion morphology than angiography. Therefore, to evaluate the effects of vascular interventions, angioscopy was performed in 68 patients with peripheral or coronary artery disease who underwent interventions.Methods and results: PTCA: Angioscopy was performed in 29 patients who underwent PTCA. The characteristics of angioscopic findings after PTCA consisted of cleft, fractures of plaques, intimal bleeding, exfoliation of endothelium and thin mural thrombi. Thermal laser anigoplasty: Angioscopy was performed 12 patients who underwent laser thermal angioplasty. Laser thermal angioplasty was performed with a Nd:YAG laser system equipped with a probe temperature programmable microprocessor that could monitor and control probe temperature simultaneously. Coagulation and carbonization were observed, when the probe temperature was over loot and 200°C, respectively. Excimer laser anigioplasty: Angioscopy was performed in 2 patients with peripheral and 25 patients with coronary artery disease who underwent excimer laser angioplasty. The excimer laser was operated at 308 nm, 135 nsec, 25 Hz and 40-60mJ/mm2 and was coupled into multifiber wire-guided catheters. The characteristics of angioscopic findings after excimer laser angioplasty consisted of flaps, fractures of plaques and abundant tissue remnants. There was no apparent thermal injury.Conclusions: These results indicate that 1) angioscopy is effective and safe for evaluation of lesion morphology after interventions, 2) excimer laser ablation does not result in thermal injury, which is commonly observed after thermal laser ablation, 3) irregular channels after recanalization and abundant tissue remnants may explain the suboptimal results after excimer laser angioplasty, and 4) all interventions may result in the same kind of mechanical vascular wall damage.

Usefulness of morphologic parameters in predicting the outcome of coronary excimer laser angioplasty

The treatment of complex coronary lesions with conventional balloon angioplasty is associated with a reduced success rate and an increased incidence of complications. To evaluate the influence of lesion morphology on the outcome of coronary excimer laser angioplasty, morphologic parameters of 148 target lesions in 147 consecutive patients were determined. Morphologic analysis included target vessel, involved vessel segment, vessel diameter, minimal lumen diameter, length of the lesion, single discret (concentric/eccentric) or complex lesions (occlusions, bifurcational, tandem or long segmental lesions), American College of Cardiology/American Heart Association Task Force classification, lesion location in curved or straight vessel segments, prestenotic vessel tortuosity and the direction of the laser approach in curved vessels with eccentric lesions. Failure of laser angioplasty occurred in 17 patients because of failed guidewire placement (n = 8), catheter placement (n = 6), or inability to pass the lesion with the laser catheter (n = 3). Successful stand-alone laser angioplasty was achieved in 68 procedures. In 63 interventions additional balloon angioplasty was necessary (n = 60) or stand-alone laser angioplasty was not successful (n = 3). The frequency of complex lesions, particularly total occlusions (p < 0.001) and prestenotic vessel tortuosity (p = 0.002) was significantly increased in the group with failed laser attempts. Statistical analysis of the morphologic parameters in successful stand-alone laser interventions compared with combined or unsuccessful interventions revealed no significant difference. These data suggest that failure of laser angioplasty occurs because of low catheter flexibility and the need for guidewire support in treating totally occluded vessels. Furthermore, once the catheter has reached the target, lesion morphology seems to be of minor importance for the success of stand-alone coronary excimer laser angioplasty.

Improved results of coronary excimer laser angioplasty by the use of advanced transmission devices

Excimer laser angioplasty is an alternative method for the treatment of obstructive coronary lesions. Initial clinical results demonstrated the safety and feasibility of the procedure. However, efficacy was limited by low catheter flexibility and unreliable energy transmission. Advanced transmission devices were used in 80 interventions in 79 patients. The catheter diameter is 1.3, 1.5 or 1.8 mm, the catheters consist of 20, 30 or 35 quartz fibres (100 μm) respectively. The mean energy density was 55 ±18 mJ mm−2, mean loss of energy transmission was 20%. The pulse width was 60 ns and 115 ns in 40 interventions each. The target vessel was the LAD in 53, the LCX in 6 and the RCA in 21 interventions.

Percutaneous excimer laser coronary angioplasty of lesions not ideal for balloon angioplasty.

Excimer laser coronary angioplasty is a new, investigational technique for treating coronary artery stenoses. Initial reports have demonstrated acute efficacy and relative safety of this procedure, but have not addressed the effect of lesion type on acute success and complication rates. In the first 100 patients undergoing percutaneous excimer laser coronary angioplasty at our institution, acute laser success was obtained in 84% and procedural success was obtained in 94%. There were six acute closures during laser angioplasty and one myocardial infarction. Two patients required emergency coronary bypass surgery. Sixty-five percent of patients had lesions not ideal for balloon angioplasty because of lesion morphology (tubular, diffuse, or chronic total occlusion) or ostial location. There were 10 tubular stenoses, 29 diffuse lesions, 18 chronic total occlusions, and eight ostial lesions, including five aorto-ostial lesions. In this nonideal subgroup, the acute success rate with laser was 86% (72% of chronic total occlusions and 91% of non-totally occluded lesions), and the procedural success rate was 94%. There were three acute occlusions during laser angioplasty but no myocardial infarctions, emergency bypass surgeries, or deaths. One coronary artery perforation occurred without clinical sequelae. Laser angioplasty was successful in four of six lesions (67%) in which balloon angioplasty had failed. Laser success was obtained in 10 of 11 (91%) moderately or heavily calcified stenoses. Eight eccentric lesions and two lesions on bends were successfully treated without dissection or perforation. No side branch occlusions occurred in the 15 patients in whom one or more major branches originated within the lesion treated. Adjunctive balloon angioplasty was performed in 47% of cases, usually to obtain a larger final luminal diameter. Need for adjunctive balloon angioplasty decreased to 36% after a larger (2.0 mm) laser catheter became available. Twenty-eight percent of the 105 lesions treated were American College of Cardiology/American Heart Association classification type A, 47% were type B, and 25% were type C. Laser and procedural successes were obtained in 83% and 97% of type A, 88% and 96% of type B, and 85% and 88% of type C lesions, respectively. In our initial experience, excimer laser angioplasty was found to be acutely effective and safe therapy for lesions identified as not ideal for balloon angioplasty. This technique may provide a useful adjunct or alternative to balloon angioplasty in selected patients.