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At least 307 records · Page 17Linked to original sources
PubMed1988

Laser welded vascular anastomosis. Comparison of CO2 and neodym yag laser techniques.

A comparative study was undertaken to investigate the application of a specially adapted microsurgical Neodymium Yag Laser system with a wavelength of 1,319 microns and a CO2 laser system for laser assisted microvascular end-to-end anastomosis (LAMA) of the rat femoral artery. Conventionally sutured anastomoses served as controls. Postoperative investigations included patency tests, light microscopy and tensile strength measurements. Both laser systems seem to be equally suitable for LAMA: The patency rates do not differ from those of sutured anastomoses and formation of microscopically small aneurysms occurred predominantly in control animals and only once in laser groups. The clamp time needed for LAMA was half the time that was needed for sutured anastomoses. Wound healing in all groups was similar with less fibrotic reactions and less foreign body granulomas in laser groups. At all intervals tensile strength was significantly higher for sutured anastomoses while differences between the CO2- and the ND: Yag-laser groups were not statistically significant. Potential applications in urology include microvascular anastomoses in erectile dysfunction, pediatric and reconstructive urology.

Anastomosis, Surgical↗
PubMed2001

Excimer laser coronary angioplasty (ELCA) for diffuse in-stent restenosis: beneficial long-term results after sufficient debulking with a lesion-specific approach using various laser catheters.

Although brachytherapy became frequently used technique for treating in-stent restenosis (ISR) in 2000 (stenosis recurrence: 14-25%), removing the tissue (i.e., debulking) is still under evaluation. Regarding XeCl Excimer laser no randomised trials have been completed so far. The entirely attainable and published data originate from five one-centre and one multicentre registries which showed a high procedural success-(98%) and a very low complication rate (<2%), but heterogeneous results based on (I) manifold laser- and lasing technology due to evolving catheter and lasing technology during the studies and (II) inhomogeneous patient-populations, which had been documented only occasionally, although we now know that ISR-recurrence rates are significantly higher in patients with (1) high grade stenosis (>70%), (2) long lesions (>15mm in length), (3) recurrent ISR. (4) ISR in saphenous vein grafts, (5) early-ISR (<3 months after stent implantation), (6) multi-vessel disease and (7) low ejection fraction. Because all athero-ablative procedures are typically finalised by adjunctive balloon PCI, diameter stenosis before adjunctive PTCA was between 23% and 64%, reflecting the different lasing (and therefor debulking) intensity between the studies. The mean lesion-length, vessel diameter, stent-type and coronary differed significantly between the studies (i.e. mean lesion length between 14 and 32 mm) and although of major influence, the speed of lasing (=ablation) was not recorded in the various studies. Concerning eccentric ELCA the invention of the area-ablation technique provide a significant greater ablation effect and the new OS-technology provide 60% more ablating area. In summary, the feasibility, effectiveness, procedural success and presumably long-term outcome of the Excimer laser for treating ISR depend on multiple outcome-influencing aspects. The lack of recording variables make analysis of various laser-for-ISR trials difficult or even impossible. ELCA seems to have advantageous procedural and long term results in lesions, where aggressive debulking effect using eccentric ELCA catheters can be achieved. The OS-catheter can provide a maximum debulking in distal lesions and tortuous vessels, where the debulking abilities of the eccentric catheter are limited. If laser debulking is inadequate (DS 30%), the incidence of recurrent restenosis appear to be higher and brachytherapy is probably more suitable. Sufficient laser debulking can only be achieved through use of precise technique respecting the laser-specific abilities of plaque dissolution, appropriate energy levels and quantities, and possibly recovery time.

Angioplasty, Laser↗
PubMed1999

[Tattoo removal Q-switched ruby laser (694 nm) and the Q-switched Nd:YAG laser (532 and 1064 nm). A retrospective study].

In a retrospective study 47 patients with 68 amateur and 25 professional tattoos were examined, considering clearance of tattoo pigments and the frequency of side effects after finished treatments with the Q-switched ruby (694 nm) and the Q-switched Nd:YAG laser (532 and 1064 nm). Black amateur tattoos were found to lighten faster than professional tattoos (13.2 and 18.6 treatments respectively). For the clearance of multicolored tattoos (amateur or professional), similar numbers of laser treatments were needed. Green pigments were removed with the Q-switched ruby laser and red pigments with the frequency-doubled Nd:YAG laser (532 nm). Compared to the Q-switched Nd:YAG laser (1064 nm), the Q-switched ruby laser and the frequency-doubled Nd:YAG laser (532 nm) more often caused blistering and transient hypopigmentation (5.4% and 7.5% vs. 1.1% (blisters); 8.6% and 15.1% vs. 4.3% (hypopigmentation).

Adult↗
PubMed1998

Radiating retinal folds detected by scanning laser ophthalmoscopy using a diode laser in a dark-field mode in idiopathic macular holes.

BACKGROUND: The pathogenesis of idiopathic macular hole is unclear. We studied the morphologic features of idiopathic macular holes using a modification of the scanning laser ophthalmoscope (SLO). METHODS: Seventy-two eyes of 57 patients with macular hole (40 women, 17 men; age 66.1 +/- 6.4 years, mean +/- SD) were included in this study. The macular holes were classified according to the Gass classification (1988). The changes around the macular holes were recorded by SLO using both a confocal aperture with a helium-neon laser (633 nm) and a ring aperture (dark-field mode) with a diode laser (780 nm) to detect fine morphologic features. RESULTS: We successfully observed minute retinal wrinkling, i.e., radiating striae (fold type) and a dome configuration (dome type), around the macular holes using the SLO dark-field mode with a diode laser, which provides a deeper retinal image because of the longer wave-length laser and the indirect mode. A helium-neon laser with a confocal aperture sometimes failed to disclose the fine retinal wrinkles. Most of the stage 2 macular holes were of the fold type. The smaller the hole, the higher the prevalence of the fold type. As the holes progressed in size, the prevalence of the dome type increased. The radiating retinal folds disappeared after successful vitreous surgery. CONCLUSION: The SLO dark-field mode with a diode laser might be useful for clear observation of fine retinal features around macular holes. The retinal folds probably indicate the presence of traction on the macula and hence may be good markers for macular repair after vitreous surgery.

Aged↗
PubMed1985

Pulsed ultraviolet lasers and the potential for safe laser angioplasty.

Endoscopic laser ablation of atheroma using continuous wave lasers is limited by imprecise control of thermal ablation, resulting in a crater that expands in width and depth, with thermal damage to adjacent normal tissue. We compared the gross and histologic effects of pulsed 308 mm excimer irradiation to continuous-wave Nd:YAG and Argon Ion laser irradiation, and pulsed 1,060 nm, 532 nm, 355 nm, and 266 nm laser irradiation in 205 atherosclerotic aortic segments. In contrast to the continuous-wave Nd: YAG, Argon Ion, and pulsed 1,060 nm, 532 nm, and 355 nm laser irradiation, which produced gross and histologic evidence of uncontrolled ablation, the 308 nm and 266 nm pulsed lasers induced incisions that conformed precisely to the beam configuration without gross evidence of thermal injury. The incision edges from these two lasers were histologically smooth and comparable to a scalpel incision. Our histologic findings suggest that rapid, precise endoscopic ablation of vascular and nonvascular tissue can be performed at these shorter pulsed wavelengths with very high precision with relatively little damage or risk to adjacent tissue.

Aorta, Abdominal↗
PubMed1994

Acute complications of excimer laser coronary angioplasty: a detailed analysis of multicenter results. Coinvestigators of the U.S. and European Percutaneous Excimer Laser Coronary Angioplasty (PELCA) Registries.

OBJECTIVES: The aim of this study was to document and analyze the incidence and consequences of complications of excimer laser coronary angioplasty. BACKGROUND: Excimer laser coronary angioplasty has been reported to be a safe and feasible alternative or adjunct to conventional balloon angioplasty, but serious and unique complications have been observed. METHODS: Data on 1,595 interventions of excimer laser coronary angioplasty in 1,521 patients were analyzed, using a merged data base from the U.S. and European Percutaneous Excimer Laser Coronary Angioplasty (PELCA) registries. RESULTS: Procedural success was achieved in 89.3% of interventions. Stand-alone laser angioplasty was performed in 17.8% of interventions. Complications included dissection (22.0%), vasospasm (6.1%), filling defects (4.8%), abrupt reclosure (6.1%), embolization (2.3%), perforation (2.4%), arrhythmia (0.7%) and aneurysm formation (0.3%). Major complications were non-Q wave myocardial infarction (2.3%), Q wave myocardial infarction (1.0%), coronary artery bypass grafting (3.1%) and death (0.7%). Logistic regression analysis revealed correlation between dissections and the use of larger catheter size (p = 0.0005), high energy per pulse levels (p = 0.0001 for native vessels), lesion length > 10 mm (p = 0.001) and presence of a side branch (p = 0.01). The incidence of perforations was higher in women (p = 0.004), in treatment of total occlusions (p = 0.02) and in the presence of a side branch (p = 0.03). Fatal complications were correlated with patients with multivessel disease (p < 0.0001), patients with acute myocardial infarction (p = 0.0009) and older patients (> 70 years old, p = 0.004). The incidence of major complications decreased after performance of 50 laser angioplasty procedures at one institution (p = 0.02). CONCLUSIONS: This analysis defines both the learning curve and the profile of complications for excimer laser angioplasty and provides insight into the selection of appropriate patients and proper performance of the procedure.

Acute Disease↗
PubMed1996

Effect of topical anti-inflammatory treatment on the outcome of laser trabeculoplasty. The Fluorometholone-Laser Trabeculoplasty Study Group.

PURPOSE: We investigated the effect of anti-inflammatory treatment on the outcome of argon laser trabeculoplasty. METHODS: In this multicenter, double-masked, randomized, placebo-controlled, parallel comparison study, 140 chronic open-angle glaucoma patients received either 0.25% fluorometholone or vehicle four times a day unilaterally, beginning 24 hours before and continuing one week after argon laser trabeculoplasty. The laser surgeon placed 50 to 60 burns over the inferior 180 degrees of the trabecular meshwork. The patients were followed up frequently for five weeks after the procedure. RESULTS: Following argon laser trabeculoplasty, signs of anterior chamber inflammation were significantly lower in the fluorometholone group. However, there was no significant difference between the fluorometholone and the vehicle groups in the incidence of increased intraocular pressure in the immediate post-argon laser trabeculoplasty period. Intraocular pressure decreased significantly in both groups from day 1 throughout the follow-up period. A significant between-group difference in intraocular pressure decrease was found only at week 5 (7.83 +/- 6.27 [S.D.] mm Hg for the fluorometholone group vs 6.63 +/- 5.79 mm Hg for the vehicle group, P = .046). No drug-related clinically significant adverse events were observed. CONCLUSIONS: Use of fluorometholone is effective in attenuating inflammation and has no clinically significant impact on the outcome of argon laser trabeculoplasty or on the incidence of intraocular pressure spikes during the immediate post-argon laser trabeculoplasty period.

Administration, Topical↗
PubMed1998

Effect of topical anti-inflammatory treatment on the long-term outcome of laser trabeculoplasty. Fluorometholone-Laser Trabeculoplasty Study Group.

PURPOSE: To investigate the effect of anti-inflammatory treatment on the long-term outcome of argon laser trabeculoplasty, we extended the short-term study of the Fluorometholone-Laser Trabeculoplasty Study Group. METHODS: Among the chronic open-angle glaucoma patients randomly assigned to the 0.25% fluorometholone or placebo eyedrops four times daily before and after argon laser trabeculoplasty in the Fluorometholone-Laser Trabeculoplasty Study, the long-term records of 27 patients (13 eyes in the fluorometholone group and 14 eyes in the placebo group) were available for our review and analysis. RESULTS: There were no statistically significant differences in the success rate of argon laser trabeculoplasty between the fluorometholone and control groups over the follow-up period of 4.6 +/- 3.4 years. CONCLUSION: While it decreased ocular inflammation and discomfort during the early postoperative period, peri-argon laser trabeculoplasty use of a topical corticosteroid did not influence the long-term intraocular pressure outcome of argon laser trabeculoplasty.

Administration, Topical↗
PubMed1997

Laser-tissue interaction during transmyocardial laser revascularization.

BACKGROUND: The clinical procedure known as transmyocardial revascularization has recently seen its renaissance. Despite the promising preliminary clinical results, the associated mechanisms are subject to much discussion. This study is an attempt to unravel the basics of the interaction between 800-W CO2 laser radiation and biological tissue. METHODS: Time-resolved flash photography was used to visualize the laser-induced channel formation in water and in vitro porcine myocardium. In addition, laser-induced pressures were measured. Light microscopy and birefringence microscopy were used to assess the histologic characteristics of laser-induced thermal damage. RESULTS: The channel depth increased logarithmically with time (ie, with pulse duration) in water and porcine myocardium. Pressure measurements showed the occurrence of numerous small transients during the laser pulse, which corresponded with channel formation, as well as local and partial channel collapse during the laser pulse. Twenty millimeters of myocardium was perforated in 25 ms. Increasing the pulse duration had a small effect on the maximum transversable thickness, but histologic analysis showed that thermal damage around the crater increased with increasing pulse duration. CONCLUSIONS: Several basic aspects of the interaction of high-power CO2 laser radiation with myocardial tissue and tissue phantoms were studied in vitro. Although the goal of this study was not to unravel the mechanisms responsible for the beneficial effects of transmyocardial revascularization, it provided important information on the process of channel formation and collapse and tissue damage.

Animals↗
PubMed1994

Laser sphincterotomy and ablation of the prostate using a sapphire chisel contact tip firing neodymium:YAG laser.

I report a modified technique for use of a contact laser for urological endoscopic surgery in spinal cord injury patients. Instead of the usual technique of passing the laser probe for surface vaporization, subsurface buttonholes were drilled with subsequent incision of the overlying tissue. As a result, creation of an adequate channel was expedited with excellent hemostasis. A total of 40 spinal cord injury patients (mean age 50.1 years, range 28 to 76) underwent transurethral surgery for bladder outlet obstruction using a sapphire contact laser tip. Of the patients 50% had undergone previous transurethral surgery and were not voiding well. Urodynamic studies demonstrated detrusor-sphincter dyssynergia in 37 patients (92.5%). A voiding cystourethrogram was done in 83% of the patients and showed vesicoureteral reflux in 17%. On cystoscopic examination 32.5% of the patients had an associated enlarged prostate, 32% stricture of the bulbous urethra and 20% bladder neck stenosis. Apart from transurethral sphincterotomy in these patients, ablation of the prostate, stricture and eradication of bladder neck stenosis, as indicated, were also done with the contact laser. Blood loss was approximately 25 to 50 ml. per procedure except for 2 initial patients with a blood loss of 100 to 150 ml. Approximately 3,500 to 8,900 joules accumulated energy were used for transurethral sphincterotomy and 11,000 to 37,000 joules for transurethral resection of the prostate. An indwelling Foley catheter was placed postoperatively for a mean of 3 days (range 1 to 8). All patients were followed for 6 to 23 months (mean 13.1). Four patients failed laser transurethral sphincterotomy: 1 due to inadequate initial incision and 3 who initially underwent laser transurethral incisions of the prostate and had persistent detrusor-sphincter dyssynergia (all had relief following laser transurethral sphincterotomy). All subsequent patients are voiding well with a wide open bladder neck and posterior urethra as shown on a voiding cystourethrogram.

Adult↗
PubMed1990

Laser assisted urethral closure in the rat: comparison of CO2 and Neodymium-YAG laser techniques.

In 65 male rats a comparative study was undertaken to investigate a Neodymium-YAG and CO2 laser system for the microsurgical repair of longitudinal incisions of the rat urethra. Postoperative investigations included patency tests, necropsy and light microscopy. Use of the laser systems did not reduce operation time. The highest rate of postoperative strictures (90%), urethral fistulas (30%), urinomas (20%) and postoperative deaths (70%) was seen in the Neodymium-YAG laser group. CO2 laser repair was almost as efficacious as microsuture repair, except for a higher rate of urethral fistulas resulting from the initially weak laser weld. Based on these findings, the Neodymium-YAG laser seems unsuitable for urethral repair. Further studies in larger animals are warranted using a CO2 laser in combination with postoperative cystostomy for urinary diversion in order to avoid fistulas in the early postoperative period.

Animals↗
PubMed1984

Lasers in urology. II. Laser therapy.

To date four laser wavelengths are commercially available which have urologic applications. The experience with all of these lasers is reviewed. The major urologic lesions treatable by the laser are: condylomata acuminata, superficial penile carcinoma, and bladder carcinoma. The carbon dioxide (CO2) laser is most applicable for external genital lesions while the Nd:YAG laser is better suited for the endoscopic treatment of bladder tumors. Due to its preferential absorption by hemoglobin, the argon laser is useful in treating vascular lesions. The tunable dye laser with hematoporphyrin-derivative therapy has exciting potential, but is too new to evaluate its therapeutic efficacy.

Argon↗
PubMed1998

Effects of pulsed Nd:YAG laser irradiation on root canal wall dentin with different laser initiators.

The effects of pulsed Nd:YAG laser irradiation with different laser initiators on the permeability and ultrastructure of the root canal wall dentin were investigated in vitro. Forty extracted human single-rooted teeth were randomly assigned to four groups. Group 1 teeth were not lased as a control. Group 2 specimens received four 10-s duration laser exposures for a total exposure of 40 s/canal. In group 3 specimens, the root canals were painted with black ink and then lased by the same method as group 2 teeth. In group 4 specimens, root canals were treated with 38% Ag(NH3)2F and then lased by the same method as group 2 teeth. Laser parameters were set at 2 W, 20 pps. After being placed in 0.6% rhodamine B solution for 48 h, the teeth were sectioned for study by stereoscope and scanning electron microscopy. Statistical analysis showed there were significant differences (p < 0.05) in dentin permeability in the apical areas between groups 3 and 1, 4 and 1, and 4 and 2. Scanning electron microscopic examination showed that laser treatment alone had no obvious effects on the root canal wall. The root canal surfaces prepared for by laser irradiation with black ink or 38% Ag(NH3)2F revealed melting, smear layer evaporation, and open dentinal tubules. Black ink was more effective than 38% Ag(NH3)2F as a Nd:YAG laser initiator.

Dental Pulp Cavity↗
PubMed2001

Treatment of tooth fracture by medium-energy CO2 laser and DP-bioactive glass paste: the interaction of enamel and DP-bioactive glass paste during irradiation by CO2 laser.

Acute trauma or trauma associated with occlusal disturbance can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible, it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. We have tried to use a continuous-wave CO2 laser and a newly developed DP-bioactive glass paste (DPGP) to fuse or bridge tooth crack or fracture lines. Both the DP-bioactive glass paste and tooth enamel have strong absorption bands at the wavelength of 10.6 microm. Therefore, under CO2 laser, DPGP and enamel should have an effective absorption and melt together. The interface between DPGP and enamel could be regarded as a mixture of DPGP and enamel (DPG-E). The study focused on the phase transformation, microstructure, functional group and thermal behavior of DPG-E with or without CO2 laser irradiation, by the analytical techniques of XRD, FTIR, DTA/TGA, and SEM. The results of XRD showed that the main crystal phase in the DPG-E was dicalcium phosphate dihydrate (CaHPO4.2H2O). It changed into CaHPO4, gamma-Ca2P2O7, beta-Ca2P2O7 and finally alpha-Ca2P2O7 with increasing temperature. In the FTIR analysis, the 720 cm(-1) absorption band ascribed to the P-O-P linkage in pyrophosphate rose up and the intensities of the OH- bands reduced after laser irradiation. In regard to the results of DTA/TGA after irradiation, the weight loss decreased due to the removal of part of absorption water and crystallization water by the CO2 laser. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight chemical bond between the enamel and DPGP. We expect that DPGP with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture.

Carbon Dioxide↗
PubMed1998

Q-switched 532-nm Nd:YAG laser trabeculoplasty (selective laser trabeculoplasty): a multicenter, pilot, clinical study.

OBJECTIVE: To investigate the safety and efficacy of a new laser procedure using a q-switched 532-nm neodymium (Nd):YAG laser, also called "selective laser trabeculoplasty," to lower intraocular pressure (IOP) in patients with open-angle glaucoma (OAG). The laser parameters were set to selectively target pigmented trabecular meshwork (TM) cells without coagulative damage to the TM structure or nonpigmented cells. DESIGN: Nonrandomized, prospective, clinical trial. PARTICIPANTS: Thirty eyes of 30 patients with uncontrolled OAG (OAG group) and 23 eyes of 23 patients with uncontrolled OAG treated previously with argon laser trabeculoplasty (ALT group) were observed for 4 to 26 weeks. Forty-four of the 53 eyes were observed for 26 weeks. INTERVENTION: Patients were treated with the Coherent Selecta 7000 (Coherent, Inc, Palo Alto, CA) frequency-doubled q-switched Nd:YAG laser (532 nm). A total of approximately 50 nonoverlapping spots were placed over 180 degrees of the TM at energy levels ranging from 0.6 to 1.2 mJ per pulse. After surgery, patients were maintained with the identical drug regimen as that before treatment. RESULTS: Both the OAG and ALT groups showed similar IOP reductions over time. Seventy percent of patients in each group responded to treatment with an IOP reduction of least 3 mmHg. At 26 weeks of follow-up, mean IOP reduction was 5.8 mmHg (23.5%, P < 0.001) for the OAG group and 6.0 mmHg (24.2%, P < 0.001) for the ALT group. The untreated eye showed a 9.7% (P < 0.001) reduction of IOP at 26 weeks. However, the IOP difference between the treated and untreated eyes was statistically significant at P < 0.003. Transient IOP elevation of 5 mmHg or greater was seen in 24% of patients. CONCLUSION: The selective laser trabeculoplasty appears to be a safe and effective method to lower IOP in patients with OAG and patients treated previously with ALT. A reduction of IOP can be achieved without coagulation of the TM.

Adult↗
PubMed2000

Comparison of carbon dioxide laser, erbium:YAG laser, dermabrasion, and dermatome: a study of thermal damage, wound contraction, and wound healing in a live pig model: implications for skin resurfacing.

BACKGROUND: Advances in laser technology allow for precise tissue removal and minimal thermal damage. However, mechanisms for cosmetic improvement have not been determined. Investigators have suggested that ablation, collagen shrinkage, and new collagen deposition all contribute to the clinical outcome. OBJECTIVE: In a live farm pig, we examined gross and microscopic effects of thermal and mechanical ablation devices to characterize immediate and long-term mechanisms in skin rejuvenation. METHODS: Two CO(2) lasers, an erbium:YAG laser, a dermabrader, and a dermatome were used to treat flank skin in a farm pig. There were 14 different treatment groups based on device type and working parameters. One to five sites were treated for each group. Wound surface areas were measured before treatment, immediately after treatment, and 7, 17, 23, 30, and 60 days thereafter. Biopsies were performed immediately after irradiation and 2, 7, 17, and 60 days after treatment. RESULTS: For the CO(2) laser-induced wounds, surface area measurements showed that immediate and final wound contraction tended to increase with initial residual thermal damage (RTD) for a range of values, above which immediate contraction remained relatively constant. Although there was no immediate wound contraction with mechanical ablation devices, long-term wound contraction in the dermatome and dermabrasion sites increased with depth of ablation. The erbium:YAG laser sites healed in a manner similar to that of mechanically induced wounds. Wound contraction profiles over time were dependent on depth of RTD and depth of ablation. Sixty days postoperatively, histologic examination showed varying degrees of fibroplasia. Overall, there was greater compaction and horizontal orientation of collagen fibers in those wounds with more than 70 microm of dermal RTD. Grossly, all wounds were similar after 60 days, with the exception of the deep dermabrasion sites, at which clinical scarring was observed. CONCLUSION: Our results show that CO(2) laser resurfacing produces short- and long-term wound contraction that is greater than that induced by purely ablative methods for the same total depth of injury. The erbium laser produced wound contraction profiles similar to those produced by mechanical wounding. The data suggest that initial collagen contraction and thermal damage modulate wound healing.

Animals↗
PubMed1985

The excimer laser: gross, light microscopic and ultrastructural analysis of potential advantages for use in laser therapy of cardiovascular disease.

Excimer lasers are pulsed gas lasers that use a mixture of a rare gas and halogen as the active medium to generate pulses of short wavelength, high energy ultraviolet light. A krypton-fluoride gas mixture was used to achieve an excimer emission at a wavelength of 248 nm. A total of 30 atherosclerotic coronary artery segments were irradiated over a range of pulse energies (250 to 750 mJ), repetition rates (2 to 25 Hz), average powers (1.9 to 18.8 watts) and cumulative exposures (3 to 12 seconds). In no case was there gross, light microscopic or ultrastructural evidence of the pathologic injury typically associated with continuous wave laser irradiation of coronary artery segments. Similar results were achieved after excimer laser irradiation of 30 samples of myocardium. Excimer irradiation of calcified aortic valve leaflets accomplished focal debridement without pathologic tissue injury; when total debridement was attempted, however, gross charring was observed. The paucity of pathologic alterations observed after excimer irradiation of cardiovascular tissue may prove beneficial in precisely controlling laser ablation of pathologic tissue without injury to the surrounding normal tissue. Clinical application of excimer laser irradiation requires resolution of several issues, including the development of suitable fiber optics and laser coupling, evaluation of potential ultraviolet toxicity, and demonstration that ultraviolet light can be transmitted through a blood-filled system.

Coronary Disease↗
PubMed2000

Early postoperative changes in regional systolic and diastolic left ventricular function after transmyocardial laser revascularization: a comparison of holmium:YAG and CO2 lasers.

OBJECTIVES: The purpose of this study was to determine the short-term effects of transmyocardial laser revascularization (TMR) on regional left ventricular systolic and diastolic function, myocardial blood flow (MBF) and myocardial water content (MWC). BACKGROUND: Clinical studies of TMR have noted a significant incidence of cardiac complications in the early postoperative period. However, the early post-treatment effects of laser therapy on the myocardium and their potential contribution to postoperative cardiac morbidity are unknown. METHODS: Swine underwent holmium:yttrium-aluminum-garnet (holmium:YAG) (n = 12) or carbon dioxide (CO2) (n = 12) laser TMR. Regional systolic function for the lased and nonlased regions was quantitated using preload recruitable work area (PRWA) and regional diastolic function with the ventricular stiffness constant alpha. RESULTS: Preload recruitable work area was significantly decreased in the lased regions both 1 (59.8+/-13.0% of baseline, p = 0.02) and 6 h (64.2+/-9.4% of baseline, p = 0.02) after holmium:YAG TMR. This decreased PRWA was associated with a significant reduction in MBF to the lased regions (13.2% reduction at 1 h, p = 0.02; 18.4% decrease at 6 h post-TMR, p = 0.01). These changes were not seen after CO2 laser TMR. A significant increase in MWC (1.4+/-0.3% increase with holmium:YAG, p = 0.004; 1+/-0.2% increase with CO2, p = 0.002) and alpha (217.4+/-44.2% of baseline 6 h post-holmium:YAG TMR, p = 0.05; 206+/-36.7% of baseline 6 h post-CO2 TMR, p = 0.03) was seen after TMR with both lasers. CONCLUSIONS: In the early postoperative setting, impaired regional systolic function in association with regional ischemia is seen after TMR with a holmium:YAG laser. Both holmium:YAG and CO2 lasers are associated with increased MWC and impaired diastolic relaxation in the lased regions. These changes may explain the significant incidence of early postoperative cardiac morbidity. The impact of these findings on anginal relief and long-term outcome are not known.

Animals↗