The Experts below are selected from a list of 3027 Experts worldwide ranked by ideXlab platform
V. Wiegand - One of the best experts on this subject based on the ideXlab platform.
-
Restenosis after excimer Laser Angioplasty of coronary stenoses and chronic total occlusions.
American Heart Journal, 1992Co-Authors: Arnd B. Buchwald, Gerald S. Werner, Christina Unterberg, E. Voth, Heinrich Kreuzer, V. WiegandAbstract:Abstract 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/mm2 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.
-
Excimer Laser Angioplasty in coronary artery disease
European heart journal, 1991Co-Authors: Gerald S. Werner, A. Buchwald, Christina Unterberg, E. Voth, Heinrich Kreuzer, V. WiegandAbstract:The results of coronary excimer Laser angiolasty were evaluated in 70 patients. Forty-five patients had Laser Angioplasty of coronary stenoses. Twenty-five patients in a total of 35 attempts had wire-guided Laser ecanalization of cronic coronary occlusions, resulting in a success rate of 71%. Immediate results in both groups demonstrated the effcacty of this thechnique without serious side-effects. Stenoses were reduced from 90±5% to 45±18% diameter reduction (mean±standard deviation) by excimer Laser agioplasty. Residual stenosis in recanalized vessels after Laser Angioplasty was 52±19%. In slightly more than half of the patients with a residual stenosis ≥50% after excimer Laser Angioplasty, subsequent balloon Angioplasty was performed for further stenoisis reduction. While satisfactory immediate results were achieved by excimer Laser Angioplasty intermediate folow-up revealed a restenosis rate in the same rage as with balloon Angioplasty.
Karl R. Karsch - One of the best experts on this subject based on the ideXlab platform.
-
Quantitative results and lesion morphology in coronary excimer Laser Angioplasty
Developments in Cardiovascular Medicine, 1993Co-Authors: Andreas Baumbach, K. K. Haase, Karl R. KarschAbstract:The quantitative results and morphologic data of the first 147 patients treated with coronary excimer Laser Angioplasty at the University of Tubingen are presented. In regard of system parameters and catheter technology three subgroups are identified. The first 60 patients were treated with a prototype 1.4 mm catheter. In the second (N = 40) and third (N = 47, 48 target lesions) series an improved catheter system with improved and trusted energy transmission was used. The catheter diameters were 1.3 mm, 1.5 mm and 1.8 mm. In the third series of patients the pulse width could be increased from 60 ns to 115 ns, resulting in a further increase of the mean energy density at the catheter tip. The use of better catheters with higher flexibility and energy transmission lead to an increase in the primary success rate of stand-alone Laser Angioplasty. The lumen achieved with successful Laser Angioplasty corresponded to the catheter diameter and was independent of longer pulse duration and higher energy density. Morphologic analysis of all target lesions showed that failure of Laser Angioplasty was significantly increased in total occlusions and lesions with prestenotic vessel tortuosity. There was no morphologic parameter that correlated with the outcome as successful standalone Laser Angioplasty.
-
Ultrasound-monitored Laser Angioplasty: preliminary clinical results.
Cardiovascular and interventional radiology, 1993Co-Authors: Stephan H. Duda, Karl R. Karsch, Peter E. Huppert, Andreas Kreis, Claus D. ClaussenAbstract:A novel coaxial catheter system for ultrasound (US)-guided, pulsed Laser Angioplasty was tested clinically in 4 patients with stenoses of the femoral and external iliac artery. The mean lesion length was 1.3±0.4 cm. The 9F multifiber Laser catheter incorporated a 4.8F commercial intravascular US catheter and can be guided over a 0.014 inch wire. Laser Angioplasty alone reduced the mean degree of stenoses from 84±8% to 47±10%. Though Laser-induced artifacts compromised detailed US monitoring during Laser firing itself, the system proved to be clinically useful as assessment of Laser effects and measurement of the severity of residual stenoses was possible immediately after Laser irradiation.
-
Case report: formation of vessel aneurysm after stand alone coronary excimer Laser Angioplasty.
Catheterization and cardiovascular diagnosis, 1992Co-Authors: Melitta B. Preisack, K. K. Haase, Wolfram Voelker, Karl R. KarschAbstract:Formation of aneurysms in coronary arteries can be observed following percutaneous transluminal balloon Angioplasty but has not been reported previously after coronary excimer Laser Angioplasty in humans. Stand alone coronary excimer Laser Angioplasty was performed in a 49-year-old man with a 75% left anterior descending artery stenotic lesion and exertional angina, documenting a good angiographic result postintervention. Control angiography 6 months after the procedure revealed an aneurysm distal to a 90% restenosis in the area of ablation.
-
Usefulness of morphologic parameters in predicting the outcome of coronary excimer Laser Angioplasty.
The American journal of cardiology, 1991Co-Authors: Andreas Baumbach, K. K. Haase, Karl R. KarschAbstract:Abstract 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
-
smooth muscle cell proliferation and restenosis after stand alone coronary excimer Laser Angioplasty
Journal of the American College of Cardiology, 1991Co-Authors: Karl R. Karsch, K. K. Haase, Manfred Wehrmann, S Hassenstein, Hartmut HankeAbstract:Abstract It has been shown that coronary excimer Laser Angioplasty can remove atherosclerotic intracoronary tissue. Stand alone coronary excimer Laser Angioplasty was successfully performed in a 53 year old white man with 90% stenosis of the left anterior descending coronary artery and exertional angina (Canadian Cardiovascular Society class III). The lesion was reduced to a 30% residual stenosis with use of a 1.2 mm and subsequently a 1.8 mm diameter Laser catheter. Early follow-up angiography 24 h later revealed persistent patency and unchanged lesion diameter of the target vessel. The patient was free of symptoms during the 2 month follow-up period, but died suddenly while playing in a tennis tournament 63 days alter the procedure. Postmortem histologic examination revealed 80% restenosis at the lesion site without plaque disruption or thrombosis. Specific staining of the histologic specimen for smooth muscle cells using alpha-actin revealed significant smooth muscle cell proliferation at the site of coronary excimer Laser Angioplasty. However, most of the vessel narrowing appeared to be due to underlying fibrotic plaque as a result of insufficient tissue ablation. This was probably related to the size of the currently available catheters, which are too small to create a large channel.
Michael P. Jones - One of the best experts on this subject based on the ideXlab platform.
-
Femoropopliteal Laser Angioplasty: Initial Clinical Results with Large Probes as "Sole Therapy"
Vascular Surgery, 1990Co-Authors: David Rosenthal, William G. Wheeler, Annette Seagraves, Michael P. JonesAbstract:Laser-assisted balloon Angioplasty has been shown to be effective in the treatment of superficial femoral artery (SFA) occlusive disease.In order to avoid the inherent trauma of balloon Angioplasty, 30 patients underwent Laser Angioplasty of the SFA as "sole therapy." Laser Angioplasty was performed using a Laser coupled to a 600 micron fiber and a 3.5 mm probe (22-28 watts). Fourteen patients had Laser Angioplasty for claudication and 16 for limb salvage. The initial success rate was 83% (25/30) (lesion length 2-14 cm). In follow-up extending to nine months, 84% (21/25) of Laser angioplastied SFAs have remained patent.By avoiding the disruptive effect on the arterial wall architecture caused by balloon Angioplasty, while at the same time ablating and vaporizing more atheromatous material with larger Laser probes, the long-term patency rates of Laser Angioplasty as sole therapy may prove to be superior to those of Laser- assisted balloon Angioplasty.
Timothy A. Sanborn - One of the best experts on this subject based on the ideXlab platform.
-
Laser Angioplasty: historical perspective.
Seminars in interventional cardiology : SIIC, 1996Co-Authors: Timothy A. SanbornAbstract:Serious interest in Laser Angioplasty began in the early 1980s in an attempt to solve two of the primary limitations of balloon Angioplasty, recanalization and restenosis. By demonstrating the ability of Laser irradiation to vaporize atherosclerotic tissue, it was logical to hypothesize that this powerful tool may allow recanalization of lesions that could not be crossed by conventional guidewire and balloon technology. With refinements in Laser fibreoptics and catheter delivery systems, several Laser systems were approved for clinical use as recanalization devices in both peripheral and coronary arteries. However, the requirement to follow Laser Angioplasty with conventional balloon Angioplasty in the majority of cases and the lack of an effect of Laser tissue removal (debulking) on restenosis has limited a broader acceptance of this technology. Perhaps improved techniques discussed later in this series such as saline infusion and better fibreoptic-lens systems will allow Laser Angioplasty to offer a true niche in interventional cardiology.
-
Coronary Laser Angioplasty
Restenosis after Intervention with New Mechanical Devices, 1992Co-Authors: Timothy A. SanbornAbstract:Laser ablation of obstructive coronary arterial lesions has been proposed as one potential modality for reducing the incidence of restenosis after Angioplasty. The rationale for this approach is multiple and includes a) removing atheromatous mass, b) decreasing medial injury and c) leaving behind a smoother, less thrombogenic surface. While these hypotheses are intriguing, to date, there has been no data to support these theories or to determine whether Lasers can actually decrease restenosis. Clinically, all of the current Laser Angioplasty systems are still in the early feasibility stage of development. The Laser generator and delivery catheters are undergoing various modifications and the Laser operating parameters are being optimized. Therefore, it is premature to consider randomized trials of Laser Angioplasty or Laser-assisted balloon Angioplasty relative to balloon Angioplasty alone. However, the preliminary results of coronary Laser Angioplasty can be summarized and the current status of the technology discussed.
-
Coronary excimer Laser Angioplasty: Reduced complications and indium-111 platelet accumulation compared with thermal Laser Angioplasty
Journal of the American College of Cardiology, 1990Co-Authors: Timothy A. Sanborn, Dimitrios Alexopoulos, Jonathan D. Marmur, Hirshel Kahn, Juan J. Badimon, Lina Badimon, Valentin FusterAbstract: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.
Herbert J. Geschwind - One of the best experts on this subject based on the ideXlab platform.
-
Clinical results of coronary excimer Laser Angioplasty: report from the European Coronary Excimer Laser Angioplasty Registry.
European heart journal, 1994Co-Authors: Andreas Baumbach, Herbert J. Geschwind, H. Oswald, J. Kvasnicka, E. Fleck, C. Özbek, N. Reifart, M. E. BertrandAbstract: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. 0f 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 13% 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) 36, 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. The data document the safety and feasibility of the currently used technology for coronary excimer Laser Angioplasty. Further advances in Laser system technology are mandatory to reduce the traumatic side effects of the ablation process.
-
Comparison of Early Recoil after Coronary Excimer Laser Angioplasty with and without Adjunctive Balloon Dilatation
Journal of Interventional Cardiology, 1994Co-Authors: Fumitaka Nakamura, Jan Kvasnicka, Herbert J. GeschwindAbstract:The immediate and early angiographic results in lesions treated solely with percutaneous coronary excimer Laser Angioplasty were compared with those obtained after combined Laser and balloon Angioplasty to determine whether early recoil may occur after coronary excimer Laser Angioplasty. The excimer Laser was operated at 308 nm, 25 Hz, 40–60 mJ/mm2/pulse and 135 nsec/pulse and coupled onto multifiber wire-guided catheters of 1.4- to 2.0-mm diameter. Thirty-five consecutive patients (32 men and 3 women; mean age 56 ± 8 years) were studied. Ten patients were treated with Laser Angioplasty alone (group I), and 25 patients were treated using Laser Angioplasty followed by balloon dilatation (group II). In group I, the minimal luminal diameter increased from 1.89 ± 0.50 mm immediately after the procedure to 2.17 ± 0.51 mm at the early follow-up (P < 0.01), whereas in group II, the minimal luminal diameter decreased from 1.89 ± 0.45 mm to 1.50 ± 0.60 mm (P < 0.005). At the early follow-up, the minimal luminal diameter of group II was significantly smaller than that of group I (1.50 ± 0.60 vs 2.17 ± 0.51 mm; P < 0.05). These data demonstrate that coronary excimer Laser Angioplasty alone results in less severe early recoil than adjunctive balloon Angioplasty. (J Interven Cardiol 1994; 7:221–228)
-
Percutaneous angioscopy after excimer Laser Angioplasty
Diagnostic and Therapeutic Cardiovascular Interventions II, 1992Co-Authors: Fumitaka Nakamura, Jan Kvasnicka, Herbert J. Geschwind, Yasumi UchidaAbstract:Angioscopy has proved 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 - 60 mJ/mm2 and was coupled into multifiber wire-guided catheters of 1.4 to 2.0 mm diameter for coronary lesions and 2.2 mm 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.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
-
Percutaneous angioscopic evaluation of luminal changes induced by excimer Laser Angioplasty
American heart journal, 1992Co-Authors: Fumitaka Nakamura, Jan Kvasnicka, Yasumi Uchida, Herbert J. GeschwindAbstract: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/mm2 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.
-
The role of shock waves in pulsed-dye Laser Angioplasty
American Heart Journal, 1991Co-Authors: Takanobu Tomaru, Herbert J. Geschwind, George Boussignac, Françoise Lange, Seung-jea TahkAbstract:Fr~~m 2nd l)ep.~rtmt~~t (11 Internal Medicine, Faculty of Medicine, Unitersiry of T~rkyo. .Ind F,xplorations Fonctionnelles and Department of Pathology, IJnivrrsity Hospital Henri Mundw, University uf Paris XII. Reprint requwts: ‘I’akanohu Tomaru. MD, 2nd Department of Internal Medicine, Faculty of Medicine. ITniversity of Tokyo. 7-3-l Hongo, Bunkyoku. ‘I’oky,,, Japan. 4/4/?9435 acteristics relevant to the shock waves have not been well elucidated. Although pulsed Lasers are being used for Laser Angioplasty,“-” the efficacy and advantage of t.he multifiber catheter for pulse Laser Angioplasty has not been well understood. In this study, we investigated the ablation characteristics of this Laser with respect to the shock waves. influence of t,he medium and guide wire on shock waves, and efficacy of the multifier catheter for Laser Angioplasty. Methods. A flash-lamp excited pulsed-dye Laser at a wavelength of 480 nm, 2.1 psec pulse duration and 10 Hz was used. Laser energy was delivered through a 200 urn optical fiber or a 1.5 mm multifiber catheter that consisted of 14 optical fibers of 150 wrn circumferential diameter arranged around a central lumen in which an 0.014.inch guide wire was inserted. Lasing was done at 100 mjoules/ pulse by the multifibercatheter or at 40 nrJoules/pulse by the single fiber. Laser irradiation was done m a 10 cm’! syringe system that was connected to a strain ::auge pressure
