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At least 145 records · Page 8Linked to original sources

PubMed1992

Contact Nd:YAG laser and CO2 laser for cylindrical excision of the cervix. A comparative study.

An excess of blood loss and persistence of intraepithelial neoplasia after cervical conization occur with some frequency. Contact Nd:YAG laser conical excision of the uterine cervix is a new technique designed to remedy those problems. In this study, 36 women with histologically confirmed cervical intraepithelial neoplasia were treated with cylindrical excision of the uterine cervix with a contact Nd:YAG laser. The results were compared with those in 30 women who had similar lesions and were treated with the CO2 laser. Use of the Nd:YAG laser resulted in less intraoperative blood loss (mean +/- SD, 3.12 +/- 0.28 vs. 30.3 +/- 2.12 mL for the CO2 laser, P less than .01) and less postoperative blood loss. The volume of early bleeding was 6.23 +/- 1.21 vs. 20.13 +/- 2.24 mL for the CO2 laser (P less than .01), and that of late bleeding was 5.22 +/- 2.21 vs. 31.24 +/- 0.05 mL for the CO2 laser (P less than .01). The operative time was similarly less for the contact Nd:YAG laser (6.2 +/- 2.2 vs. 20.2 +/- 1.2 minutes for the CO2 laser, P less than .01). The dimensions of the excised specimens were similar. These findings suggest that the contact Nd:YAG laser offers distinct advantages over the CO2 laser in performing cylindrical excision of the cervix.

Blood Loss, Surgical↗

PubMed1995

Laser sclerostomy ab externo using two different infrared lasers: a clinical comparison.

This study was designed to compare the clinical results of an ab externo approach to laser sclerostomy using two different laser sources under identical conditions. A pulsed (200 microseconds) erbium-YAG laser (lambda = 2940 nm) and a pulsed (200 microseconds) holmium:YAG laser (lambda = 2120 nm) were used. The energy of each laser was transmitted via a fiber (300 microns in diameter) and applied near the limbus, with the fiber tip remaining in steady contact with the sclera. According to the higher tissue absorption coefficient, a shorter penetration depth and, therefore, fewer complications were expected for the Er:YAG laser. A total of 26 patients with advanced open-angle glaucoma were treated and followed for up to 6 months. In all cases a functioning fistula with a prominent filtering bleb and a marked reduction in the intraocular pressure (from up to 35 mm Hg to < 10 mm Hg) could be achieved primarily. The total energy required was about 4 times lower for erbium:YAG laser was compared with holmium:YAG laser sclerostomies. No complication occurred intraoperatively. Postoperatively, reversible adherence of the iris to the internal ostium was more frequently observed in Ho:YAG laser sclerostomies (60%) and small hyphemas were more often seen in Er:YAG laser sclerostomies (30%). After 6 months of follow-up, about 40% of the fistula remained patent in both groups. In principle, both lasers are suited to serve as energy sources for the described approach. Under the conditions of the present study, different levels of thermal effects did not cause any significant difference in the clinical success rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Histological comparison of corneal ablation with Er:YAG laser, Nd:YAG optical parametric oscillator, and excimer laser.

PURPOSE: To use histological techniques to assess and compare the ablation depth, local damage, and surface quality of corneal ablations by a Q-switched Er:YAG laser, an optical parametric oscillator laser at 2.94 microm, a long pulse Er:YAG laser, and a 193-nm excimer laser. METHODS: Human cadaver eyes and in vivo cat eyes were treated with a 6.0-mm diameter, 30-microm-deep phototherapeutic keratectomy ablation and a 6.0-mm diameter, -5.00-D photorefractive keratectomy ablation. Human cadaver eyes were also treated with a 5.0-mm diameter, -5.00-D laser in situ keratomileusis (LASIK) ablation. Fluences and pulse widths used were 200 mJ/cm2 and 70 ns for the Q-switched Er:YAG, 150 mJ/cm2 and 7 ns for the optical parametric oscillator laser (OPO), 500 mJ/cm2 and 50 microseconds for the long pulse Er:YAG, and 160 mj/cm2 and 20 ns for the excimer laser. In the ablation rate study, 12 porcine eyes were ablated by the OPO laser with a range of layers and at different fluences ranging from 60 to 150 mJ/cm2, all using a 1.5-mm spot on the eye. The ablation depth of these acute ablations was evaluated by light microscopy examination. RESULTS: In the acute damage study, light microscopy showed a thin surface layer in all samples with minimal thermal damage except on the long pulse Er:YAG corneas. Transmission electron microscopy revealed less than 0.3-microm surface damage for all specimens of both the optical parametric oscillator and the excimer laser samples with no evidence of collagen shrinkage. Transmission electron microscopy showed damage layers of 0.5 to 3 microm for Q-switched Er:YAG and 3 to 10 microm for long pulse Er:YAG. Scanning electron microscopy showed smooth surfaces in all eyes, although the excimer was the roughest. In the porcine eye study, ablations were produced in both PTK and PRK modes with the ablation rate per layer increasing with the fluence. At 120 mJ/cm2, the average ablation rate was 1.9 microm per layer. CONCLUSIONS: The histology from the short pulse mid-infrared optical parametric oscillator laser at 2.94 microm was comparable to the 193-nm excimer with a smooth, damage-free, ablation zone when performing PRK and LASIK.

Algorithms↗

PubMedDate not supplied

A systematic histologic analysis of nonablative laser therapy in a porcine model using the pulsed dye laser.

BACKGROUND: To our knowledge, no systematic analysis of nonablative laser therapy has been performed. OBJECTIVE: To alter the parameters (fluence, spot size, pulse duration, and use of cooling spray) for the pulsed dye laser to determine the precise settings that would yield the most favorable dermal remodeling in a porcine model. METHODS: Research was conducted in an animal laboratory at Albany Medical College. An anesthetized Yucatan miniature pig was subjected to a pulsed dye laser at various parameters. After 10 weeks, the laser-treated areas were harvested and processed for blinded, randomized, histologic evaluation. Negative (nontreated skin) and positive (ablative carbon dioxide laser-treated skin) controls were compared with the nonablative pulsed dye laser-treated areas. MAIN OUTCOME MEASURES: Quantitative assessment of collagen band width and cells per high-power field and qualitative assessment of epidermal and dermal changes. RESULTS: A significant difference (P<.001) in collagen band width was evident when nonablative laser-treated skin and carbon dioxide ablative laser-treated skin specimens were compared with untreated skin specimens, but no significant (P =.18) difference existed between the nonablative and ablative modalities. Similarly, cellular hypertrophy, as measured by high-power field, corroborated the previous findings. Furthermore, a higher fluence, a larger spot size, and a longer pulse duration proved statistically significant for increased collagen band width (P =.01, P<.001, and P<.001, respectively), and a larger spot size and a longer pulse duration exhibited significance for cells per high-power field (P =.02 and P =.009, respectively), with a trend toward significance for higher fluence (P =.09). Overall, the dermis was considerably thicker for nonablative and ablative laser-treated areas compared with untreated skin, but this could not be quantified because the depth exceeded the punch biopsy instrument. The epidermis remained unchanged. CONCLUSIONS: The nonablative pulsed dye laser has demonstrated favorable histologic evidence of dermal remodeling, and its effects were similar to histologic changes seen with the carbon dioxide ablative laser, both of which were statistically significant compared with untreated skin, as seen in this preliminary animal model.

Animals↗

PubMed1998

Thermic effects in the "vestibule" during laser stapedotomy with pulsed laser systems.

BACKGROUND AND OBJECTIVE: Apart from the ablation properties at the stapes footplate, the degree of thermic loading in the inner ear is important in determining the suitability of pulsed lasers for stapedotomy. The aim of the study is to compare the thermic effects in the vestibule with different pulsed laser systems. STUDY DESIGN/MATERIALS AND METHODS: Temperature increases and heat exchange processes in the fluid (physiological saline) were examined in a calorically and physiologically approximated cochlea model for applying the laser parameters effective in creating footplate perforations. RESULTS: With all systems, increases in the energy density, number of pulses, and thus resultant total energy lead to higher temperatures. In the effective energy density range, the highest temperature increases achieved with the requisite number of pulses at a distance of 2 mm behind the perforation are 26 degrees C with the Ho:YAG laser. The lowest temperature maxima are 5.5 degrees C with the Er:YAG and <5 degrees C with the Er:YSGG laser. The excimer laser, investigated at only one energy density, showed maximal temperatures of 10 degrees C. CONCLUSION: The Er:YSGG and Er:YAG laser can be applied in laser stapedotomy in a relatively broad energy density range without a risk of inner ear damage by thermic loading. On the other hand, the Ho:YAG laser is not recommended for stapedotomy because of the higher energy density and pulse rate required for sufficient perforation and the resultant higher temperature increases in the perilymph. Though likewise achieving perforations with only slight temperature increases in the fluid of the cochlea model, the excimer laser does not seem appropriate for stapedotomy because of the long period of heat exposure (ca. 60 s) due to the lower ablation rate at the stapes necessitating a longer application time.

Cochlea↗

PubMed2000

Scanning laser polarimetry measurements after laser-assisted in situ keratomileusis.

PURPOSE: To evaluate the effect of laser-assisted in situ keratomileusis on retinal nerve fiber layer thickness measurements obtained with scanning laser polarimetry. METHODS: Thirteen consecutive eyes (13 patients) undergoing laser-assisted in situ keratomileusis were enrolled in this prospective study. Scanning laser polarimetry (NFA-GDx; Laser Diagnostic Technologies, Inc, San Diego, California) examination was performed 1 week before and 1 to 8 weeks after laser-assisted in situ keratomileusis surgery. Intraocular pressure was normal at all preoperative and postoperative examinations. Total mean, and superior, temporal, inferior, and nasal mean retinal nerve fiber layer thickness values before and after laser-assisted in situ keratomileusis were compared by Student paired t test. RESULTS: Mean +/- SD patient age was 34.6 +/- 10.9 years (range, 20 to 56 years). Mean +/- SD preoperative spherical equivalent refractive error was -6.6 +/- 3.1 diopters (range, -3.25 to -13.25 diopters) and mean +/- SD spherical equivalent refractive surgical correction was -6.2 +/- 3.0 diopters (range, -2.9 to -12.25 diopters). Total mean retinal nerve fiber layer and superior, inferior, temporal, and nasal mean retinal nerve fiber layer thicknesses were thinner after laser-assisted in situ keratomileusis (P =.01, for all comparisons, paired t test). CONCLUSIONS: Measurements of the retinal nerve fiber layer with scanning laser polarimetry depend on a corneal compensator inherent in the device. Keratorefractive surgery may affect scanning laser polarimetry measurements.

Adult↗

PubMed2002

The role of the laser pulse duration in infrared matrix-assisted laser desorption/ionization mass spectrometry.

The role of the laser pulse duration in matrix-assisted laser desorption/ionization mass spectrometry with infrared lasers (IR-MALDI-MS) emitting in the 3 microm wavelength range has been evaluated. Mass spectrometric performance and characteristics of the IR-MALDI process were examined by comparing a wavelength-tuneable mid-infrared optical parametric oscillator (OPO) laser of 6 ns pulse duration, tuned to wavelengths of 2.79 and 2.94 microm, with an Er:YAG laser (lambda = 2.94 microm) with two pulse durations of 100 and 185 ns, and an Er:YSGG laser (lambda = 2.79 microm) with a pulse duration of 75 ns. Threshold fluences for the desorption of cytochrome C ions were determined as a function of the laser pulse duration for various common IR-MALDI matrices. For the majority of these matrices a reduction in threshold fluence by a factor of 1.2-1.9 was found by going from the 75-100 ns long pulses of the Erbium lasers to the short 6 ns OPO pulse. Within the experimental accuracy threshold fluences were equal for the 100 and the 185 ns pulse duration of the Er:YAG laser. Some pronounced pulse duration effects related to the ion formation from a glycerol matrix were also observed. The effect of the laser pulse length on the duration of ion emission was furthermore investigated.

Angiotensin I↗

PubMed1994

The removal of cutaneous pigmented lesions with the Q-switched ruby laser and the Q-switched neodymium: yttrium-aluminum-garnet laser. A comparative study.

BACKGROUND: The Q-switched ruby laser (QSRL) (694 nm) has been used successfully in the removal of tattoos and a variety of cutaneous pigmented lesions. The frequency-doubled Q-switched neodymium:yttrium-aluminum-garnet laser (QSNd:YAG) (1064 and 532 nm) has also been shown to be effective in the treatment of tattoos, however, little has been published regarding the QSNd:YAG laser in the removal of cutaneous pigmented lesions. OBJECTIVE: The purpose of this study is to compare the efficacy and side effect profile of the QSRL and the frequency-doubled QSNd:YAG lasers in the removal of cutaneous pigmented lesions, including lentigines, café-au-lait macules, nevus of Ota, nevus spilus, Becker's nevus, postinflammatory hyperpigmentation, and melasma. METHODS: Twenty patients with pigmented lesions were treated with the QSRL and the frequency-doubled QSNd:YAG lasers. Clinical lightening of the lesion was assessed 1 month after a single treatment. Side effects and patient satisfaction were also evaluated. RESULTS: A minimum of 30% lightening was achieved in all patients after only one treatment with either the QSRL or the frequency-doubled QSNd:YAG laser. The QSRL seems to provide a slightly better treatment response than the QSNd:YAG laser. Neither laser caused scarring or textural change of the skin. Most patients found the QSRL to be more painful during treatment, but the QSNd:YAG laser caused more postoperative discomfort. CONCLUSION: Both the QSRL and the frequency-doubled QSND:YAG laser are safe and effective methods of treatment of epidermal and dermal pigmented lesions.

Adult↗

PubMed1995

[Modifying the stapes footplate with various laser systems. II. The pulsed laser].

The object of the present study was to examine the tissue ablation capacity of various pulsed lasers at the stapes footplate. Isolated human stapes and bovine compact-bone platelets (thickness 90 microns) were used to determine effective laser parameters for achieving a perforation measuring 500 microns to 600 microns in diameter. Apart from achieving the perforation diameters, particular attention was given to the form and quality of the perforations, reproducibility of the perforation effect and the thermally altered border zones occurring at the footplate. Four pulsed laser systems were used: excimer, Ho:YAG, Er:YSGG and CO2 lasers. An adequately large perforation generally could only be achieved by several repeated shots at the same application site, since only a small amount of tissue was ablated per application. The mechanism of the photoablation caused the extent of the thermal side effects to be markedly lower than with the continuous wave (cw) and superpulse systems. For this reason and because of their highly reproducible perforation effect, they were basically better suited for stapedotomy than the cw systems. It was possible, however, that as a result of the longer application time and the need to repeatedly irradiate the same application site, the higher pulse counts could prove to be disadvantageous in clinical practice. Among the pulsed laser systems, the Er:YSGG laser had the highest ablation rate at the stapes and was thus the most effective laser for interventions at the footplate. Although somewhat less effective than the Er:YSGG laser in our studies, the Ho:YAG and pulsed CO2 lasers also appear to be suitable for stapes surgery. On the other hand, we did not consider the excimer laser (308 nm) to be particularly effective at the footplate because of its low ablation rates.

Animals↗

PubMed1993

Comparison of laser-assisted anastomosis, laser welding, and microsurgical anastomosis of rabbit uterine tubes.

OBJECTIVE: To assess laser-assisted anastomosis in fallopian tube reconstruction. METHODS: Fifty-two rabbit uterine tubes were transected and subjected to laser welding or to microsurgical or laser-assisted anastomosis in a randomized paired design, and compared with the contralateral side. The time required for the procedure, patency of the uterine tubes, amount of adhesion formation, and quality of scar tissue (grossly and histologically) were evaluated 4 weeks after surgery. RESULTS: Traditional microsurgical procedures required significantly longer operative time than laser-assisted anastomosis (64.4 +/- 2.2 versus 41.3 +/- 2.2 minutes) or laser welding (47.8 +/- 3.0 versus 24.5 +/- 3.0 minutes). Patency was established in all 52 uterine tubes. Adhesion formation was animal-dependent rather than procedure-dependent. All scars healed well and most were not visible beyond residue suture. Inflammatory cells were noted around the suture sites; however, gross observation revealed that all mucosal surfaces over the scars were smooth. One of 18 laser-welded uterine tubes developed dehiscence, whereas there was no dehiscence in laser-assisted or microsurgically anastomosed uterine tubes. CONCLUSION: Laser-assisted anastomosis is superior to laser welding or microsurgical anastomosis in rabbit uterine tubes. Laser-assisted anastomosis has potential use in fallopian tube reconstruction.

Anastomosis, Surgical↗

PubMed1996

Are copper vapour and frequency doubled Nd:YAG lasers superior to the argon laser for portwine stains at pulse widths of 30-50 milliseconds?

BACKGROUND AND OBJECTIVE: The copper vapour laser (CVL) and the frequency doubled Nd:YAG laser (FDNYL) have been increasingly adopted as alternatives to the argon laser for treating vascular skin lesions. Automated scanning devices that permit the use of any of these lasers at 30-50 ms pulse widths are now widely used. The object of this study was to compare the CVL and FDNYL with the argon laser using pulse widths in the 30-50 ms range. STUDY DESIGN/MATERIALS AND METHODS: Thirty-one adult patients with red-purple or purple portwine stains (PWS) were treated with a CVL at 578 nm, a FDNYL at 532 nm, and an argon laser at 488/514 nm. Test areas were performed using a Hexascan delivery system and an energy fluence just sufficient to produce immediate tissue change. Pulse widths were maintained constant for each patient (mean 40 msec). The mean fluences used were 13.1 J/cm2, 13.2 J/cm2, and 13.0 J/cm2, respectively. Assessments were made after 4 months using a clinical fading score and an index of light absorbence derived from reflectance spectrophotometry. RESULTS: Fading scores were statistically significantly better with the CVL (score = 2.29) than the FDNYL (score = 1.83, P < 0.02) and the argon laser (score = 1.89, P < 0.003). The differences between the FDNYL and the argon laser were not significant. Although there was a trend toward lower light absorbence index with the CVL than the argon laser and FDNYL (scores = 177, 179 and 181, respectively), these differences were not statistically significant. CONCLUSIONS: Despite slightly better results with the CVL in terms of the fading produced, differences among the CVL, FDNYL, and argon lasers are small when 30-50 ms pulse widths are employed and are of doubtful clinical significance for darker PWS.

Absorption↗

PubMed1998

Laser nerve repair by solid protein band technique. I: identification of optimal laser dose, power, and solder surface area.

Thirty-four tibial nerves in 17 adult male wistar rats were repaired by applying protein bands longitudinally across the nerve join. The bands were then irradiated with a fibre-coupled diode laser (lambda = 810 nm). The relations among the laser weld breaking force, the power, and the solder surface area were investigated, while maintaining a consistent ratio between the total mass of protein solder in a band and total laser energy delivered (the laser energy dose). When this laser energy dose was held constant, the average breaking force of the laser welds irradiated by 72 mW laser output power was weaker than that reached after 90 mW laser radiation. There is a linear relation between the solder breaking force and the solder surface area when band thickness, laser power, and laser dose are unvaried.

Animals↗

PubMed2000

Low level laser therapy (classes I, II and III) for the treatment of osteoarthritis.

BACKGROUND: Osteoarthritis (OA) affects a large proportion of the population. Low Level Laser Therapy (LLLT) is a light source that generates extremely pure light, of a single wavelength. The effect is not thermal, but rather related to photochemical reactions in the cells. LLLT was introduced as an alternative non-invasive treatment for OA about 10 years ago, but its effectiveness is still controversial. OBJECTIVES: To assess the effectiveness of LLLT in the treatment of OA. SEARCH STRATEGY: We searched MEDLINE, EMBASE, the Cochrane Musculoskeletal registry, the registry of the Rehabilitation and Related Thereapies field and the Cochrane Controlled Trials Register up to January 30, 2000. SELECTION CRITERIA: Following an a priori protocol, only controlled clinical trials of LLLT for the treatment of patients with a clinical diagnosis of OA were eligible. Abstracts were excluded unless further data could be obtained from the authors. DATA COLLECTION AND ANALYSIS: Two reviewers independently selected trials and abstracted data using predetermined forms. Heterogeneity was tested with Cochran's Q test. A fixed effects model was used throughout for continuous variables, except where heterogeneity existed, in which case, a random effects model was used. Results were analyzed as weighted mean differences (WMD) with 95% confidence intervals (CI), where the difference between the treated and control groups was weighted by the inverse of the variance. Standardized mean differences (SMD) were calculated by dividing the difference between treated and control by the baseline variance. SMD were used when different scales were used to measure the same concept (e.g. pain). Dichotomous outcomes were analyzed with odds ratios. MAIN RESULTS: Five trials were included, with 112 patients randomized to laser, 85 patients to placebo laser. Treatment duration ranged from 4 to 10 weeks. Pain was assessed by four trials. The pooled estimate (random effects) of three trials showed no effect on pain measured using a scale (SMD: -0.2, 95% CI: -1.0, +0.6), but there was statistically significant heterogeneity (p>0,05). Two of the trials showed no effect and one demonstrated very beneficial effects with laser. In another trial, with no scale-based pain outcome, significantly more patients reported pain relief (yes/no) with laser with an odds ratio of 0.05, (95% CI: 0.0 to 1.56). Other outcomes of joint tenderness, joint mobility and strength were not significant. REVIEWER'S CONCLUSIONS: For OA, the results are conflicting in different studies and may depend on the method of application and other features of the LLLT application. Clinicians and researchers should consistently report the characteristics of the LLLT device and the application techniques used. New trials on LLLT should make use of standardized, validated outcomes. Despite some positive findings, this meta-analysis lacked data on how LLLT effectiveness is affected by four important factors: wavelength, treatment duration of LLLT, dosage and site of application over nerves instead of joints. There is clearly a need to investigate the effects of these factors on LLLT effectiveness for OA in randomized controlled clinical trials.

Humans↗

PubMed1980

A dual laser flow sorter utilizing a CW pumped dye laser.

A dual laser flow sorter has been constructed from an existing single laser system by incorporating a dye laser as the second laser source. The argon ion laser emission was used both as a pump laser and as a source by beam splitting before entrance to the dye laser. The emissions of the dye laser and pump laser beams were recombined and focused with the same optical train used in the single laser system. The imaging on the stream of the flow sorter provided for spatial and thus temporal separation of the exciting beams and subsequent sample emissions.

Cell Separation↗

PubMed2001

The 980-nm diode laser as a new stimulant for laser evoked potentials studies.

BACKGROUND AND OBJECTIVE: Lasers have been used as stimulators for creating pain response without stimulating mechanoreceptive fibers. Various laser systems are still under investigation on the quest for best laser system. Our objective was to test the feasibility of the 980-nm diode laser for LEP (laser evoked potentials) studies. STUDY DESIGN/MATERIALS AND METHODS: Laser evoked potentials created by using the 980-nm diode laser were recorded by using standard electroencephalogram (EEG) techniques. The collimated laser beam was 3 mm in diameter. Stimulus duration was set to 200 msec. The power of laser stimulus exposed to the dorsum of the right hand of 10 healthy volunteer subjects (5 women and 5 men) was varied between 0 and 10 watts to determine the pain threshold. EEG signals during the exposure of 1.5 times the threshold value were recorded from scalp electrodes placed on areas Fz, Cz, Pz, C3, and C4 according to the international 10--20 system. The stimulus presented during the EEG recording was described as a bearable pain sensation like a pinprick perception by the subjects. After 0.1--30 Hz analog low-pass filtering, 100-msec prestimulus, and 900-msec poststimulus EEG epochs were recorded at 256 Hz sampling rate and evaluated statistically. Thirty stimuli were presented by randomly varying the interstimulus duration between 5 and 9 seconds. RESULTS: Latency and amplitude values of LEPs were found in accordance with those reported in the literature. CONCLUSION: The 980-nm diode laser used is a suitable stimulator for LEP studies.

Adult↗

PubMed1993

In vitro decalcification of aortic valve leaflets with the Er:YSGG laser, Ho:YAG laser, and the Cavitron ultrasound surgical aspirator.

This study was designed to compare the efficacy of the erbium:yttrium-scandium-gallium-garnet (Er:YSGG) laser and the holmium:yttrium-aluminum-garnet (Ho:YAG) lasers in debriding calcium from freshly explanted aortic valve leaflets and to compare the Er:YSGG laser with the Cavitron ultrasonic surgical aspirator (CUSA). Aortic valve leaflets were freshly explanted from patients undergoing aortic valve replacement for aortic stenosis. Initially, 4 leaflets each were debrided with the Er:YSGG and the Ho:YAG lasers to attempt removal of calcium deposits while preserving the underlying integrity of the leaflets and minimizing thermal damage. The Er:YSGG laser was more effective in doing so with less thermal and photoacoustic damage when compared with the Ho:YAG laser. Twelve more leaflets each were then debrided with the Er:YSGG laser and the CUSA. The Er:YSGG laser again proved less injurious to the underlying leaflet. The CUSA-treated leaflets demonstrated shattering and disruption of adjacent tissue as well as collagen fiber exposure. These changes were not seen with the Er:YSGG laser. Because of these properties, the Er:YSGG laser merits further evaluation as a tool for aortic valvuloplasty procedures in selected patients with senescent calcific aortic stenosis.

Aortic Valve↗

PubMed1993

Soft tissue studies with 805 nm diode laser radiation: thermal effects with contact tips and comparison with effects of 1064 nm Nd:YAG laser radiation.

This study compares the perioperative depths of thermal coagulation, charring, and incision in rabbit liver, internal anterior abdominal wall skeletal muscle, and abdominal skin and in swine liver and abdominal skin obtained with 805 nm diode laser and 1,064 nm Nd:YAG laser radiation using 300-microns-diameter conical-tip and 1,200-microns-diameter spherical-tip contact fibers by hand. Additionally, the total depth of tissue necrosis surrounding incisions made with both lasers and contact tips is determined 48 hours postoperatively in the three tissues, and healing of the liver and abdominal wall muscle 21 and 35 days postoperatively is assessed histologically. Perioperatively determined charring, coagulation, and incision depth obtained in all tissues with either 805 nm or 1,064 nm laser radiation were sensibly equivalent at equal laser power values for each of the two contact tip shapes tested. At equal laser power values, coagulation depths obtained in rabbit abdominal skin using the 300-microns-diameter conical tip differed significantly (P < or = 0.01) from those values obtained with the 1,200-microns-diameter spherical tip. Incision depths obtained with the two different contact tip shapes at equal laser power settings in the different tissues studied differed in a few instances with no apparent pattern relating to tissue type or laser power. Depth of incisions obtained with both laser and tip types increases in the range of 6-12 w, but plateaus in the range 12-18 w in the tissues studied. Incisions obtained with both diode and Nd:YAG laser contact were essentially hemostatic, with self-limiting oozing at most.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Muscles↗

PubMed2005

High-power laser vaporization of the canine prostate using a 110 W Thulium fiber laser at 1.91 microm.

INTRODUCTION: The Thulium fiber laser may have several advantages over current urology lasers, including smaller size, more efficient operation, improved spatial beam quality, more precise tissue incision, and operation in pulsed or continuous-wave modes. Previous laser-tissue interaction studies utilizing the Thulium fiber laser have been limited to laser powers of less than 5 W, restricting potential medical applications. This study describes the preliminary testing of a high-power Thulium fiber laser for vaporization of the canine prostate, ex vivo. STUDY DESIGN/MATERIALS AND METHODS: A continuous-wave, 110-W Thulium fiber laser operating at a wavelength of 1.91 microm, delivered 88.5+/-2.3 W of power through a 600-microm-core silica fiber for non-contact vaporization of canine prostates (n = 6). RESULTS: The Thulium fiber laser vaporized prostate tissue at a rate of 0.83+/-0.11 g/minute. The thermal coagulation zone measured 500-2,000 microm, demonstrating the potential for hemostasis. CONCLUSIONS: The high-power Thulium fiber laser is capable of rapid vaporization and coagulation of the prostate. In vivo animal studies are currently being planned for evaluation of the Thulium fiber laser for potential treatment of benign prostate hyperplasia (BPH).

Animals↗