bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary report on use of the neodymium‐YAG laser in plastic surgery
Authors: Apfelberg David B. , Smith Teruko , Lash Harvey , White David N. , Maser Morton R.
Published: March 2007

Thirty‐four patients with 57 cutaneous lesions have been treated with the Nd:YAG laser under an experimental protocol over a year of study. The majority of treatments were done on an outpatient basis under local anesthesia. Capillary/cavernous hemangiomas of the oral cavity responded well, but hemangiomas of infancy responded poorly. Hypertrophic scars and keloids responded well only in conjunction with steroid treatment. Epistaxis in patients with hereditary hemorrhagic telangiectasia responded well for 4–5 months and then recurred. Areas with thin skin or mucosa have the potential for full‐thickness injury with complications of scar, bony exposure, or septal perforation.
Residual cervical intraepithelial neoplasia after laser ablation
Authors: MacLean A. B. , Murray E. Leslie , Sharp F. , More I. A. R.
Published: March 2007

Some patients with histologically proven residual cervical intraepithelial neoplasia after laser ablation have false negative cytology. The explanation for this is not known, but there was not evidence of buried lesions. Follow‐up of all patients treated by selective ablation is necessary. Cytology alone is inadequate and careful, accurate pre‐ and posttherapy colposcopy is essential.
Dosimetry study of Nd:YAG laser damage to canine renal cortex
Authors: Benderev Theodore V. , Chmiel Joan S. , Carone Frank A. , Schaeffer Anthony J.
Published: March 2007

A dosimetry study of factors affecting the extent of tissue damage inflicted upon the canine renal cortex by the Neodymium: Yttrium Aluminum Garnet (Nd:YAG) laser was undertaken. Laser parameters and renal tissue conditions were varied independently in duplicate in the following manner: (1) power ‐ 5, 10, 20, 50, 75, 100 watts with a spot size of 1.2 mm; (2) exposure duration ‐ 1, 2, and 4 seconds; (3) kidney perfusion and temperature ‐ renal artery unclamped (perfused) without cooling; renal artery clamped (non‐perfused) without cooling; and renal artery clamped with cooling. Five days following application of the laser, the animals were sacrificed and serial sections of the renal cortex were examined for maximum depth and width of tissue damage and ablation. Multiple linear regression analysis of the data indicated a direct linear relationship between the joules (watts x seconds) of energy delivered to the renal cortex and the depth and width of tissue damage and ablation (p<0.001 for joule regression coefficient for each variable). Seconds and/or watts alone were not major predictors of the outcome after accounting for joules. Clamping the main renal artery significantly reduced the depth and width of laser damage when compared to the perfused kidney (p<0.001 for each variable). The depth of damage was similar in the cooled and the non‐cooled non‐perfused kidney.

These data suggest that increased laser energy and kidney perfusion significantly increase renal cortical laser induced damage. Adjustment of these parameters may permit controlled tumor ablation or tissue incision with minimal damage to adjacent normal tissue.
Recanalization of occluded biliary endoprostheses with pulsed laser radiation
Authors: Nishioka Norman S. , Kelsey Peter B. , Kibbi Abdul‐Ghani , Mihm Martin C. , Anderson R. Rox
Published: March 2007

The use of pulsed laser radiation to recanalize occluded biliary endoprostheses was examined. In vitro measurements demonstrated that a repetitively pulsed organic dye laser transmitted through a small diameter quartz fiber can recanalize an occluded stent in less than 10 sec without causing visible damage to the stent. The laser parameters required for recanalization do not result in significant damage to the common bile duct of a pig even when the laser energy is delivered directly into the tissue, indicating that biliary endoprostheses can be cleared with a large margin of safety. Although the duration of this effect is unknown, pulsed laser radiation is a simple, safe, and effective means of recanalizing occluded biliary endoprostheses and may be an alternative to stent replacement.
Koilocytotic, virus‐induced pre‐neoplasia in women: A multifocal disease effectively treated with CO2‐laser surgery
Authors: Rubinstein Eli
Published: March 2007

A superficial koilocytotic lesion progressing to dysplasia and later into an aggressive invasive cervical cancer has been demonstrated. It is thought that these lesions create an area of susceptibility to neoplasia in the cervix, vagina, and in the vulva, and are defined as preneoplastic lesions.

A total of 57 young women have been examined cytologically and colposcopically at least 3, 6, and 12 months following CO2‐laser surgery. In 12 women (21%) the lesions were multifocal with the same histological pattern in the cervix and in the vagina and/or in the vulva. CO2‐laser effectively eradicates the koilocytotic lesions in the cervix and in the vagina; in the vulva, however, relapses are common after an initial good effect.

The diagnostic accuracy of cervicovaginal cytology was low: exfoliated koilocytotic cells were found in only 26.3% out of 57 cases with histologically proven koilocytotic lesion, even when the cytological smears were reexamined.
Response of peripheral nerve to He‐Ne laser: Experimental studies
Authors: Rochkind S. , Nissan M. , Barr‐Nea L. , Razon N. , Schwartz M. , Bartal A.
Published: March 2007

Low‐energy He‐Ne laser irradiation (LELI) was found to affect the electric activity and morphology in both intact and severely injured peripheral nerves in rats. Action potential (AP) in the healthy nerve increased by 33% following a single transcutaneous irradiation. Similar irradiation in crushed nerves caused AP to increase significantly over the AP of nonirradiated crushed nerve. Morphological observations revealed that a laser‐irradiated injured nerve had diminished scar tissue as compared to an injured but not an irradiated nerve.
Photodynamic therapy for treatment of malignant cutaneous lesions
Authors: Waldow Stephen M. , Lobraico Rocco V. , Kohler Irmgard K. , Wallk Silas , Fritts Helen T.
Published: March 2007

Photodynamic therapy, employing either hematoporphyrin derivative or dihematoporphyrin ether as the photosensitizer and an argon‐pumped tunable dye laser as the activating light source, was used to treat ten patients who had primary or recurrent basal or squamous cell carcinoma or infiltrating ductal cell carcinoma lesions metastatic to the skin. Of the 155 sites that were treated, various degrees of edema, erythema, and necrosis, sometimes accompanied by blistering, were evident in all areas within 24 to 48 hours of light treatment. While our follow‐up periods are short, four patients are free of disease at eight months or more posttreatment, two patients have had recurrent and/or persistent disease within four months, and four patients died within nine months from metastatic disease or unrelated disorders. Continued investigation into the use of photodynamic therapy for treatment of malignant lesions appears warranted, based on these preliminary clinical results.
Injuries as an adverse reaction to clinically used laser devices
Authors: Rodriguez Juan G. , Sattin Richard W.
Published: March 2007

Since the first use of lasers in ophthalmology in the early 1960s, applications for the medical laser have been found in many medical specialties. Despite their increasing usefulness, lasers have been reported to induce injuries. Few studies have tried to quantify the number of injuries caused by the clinical use of lasers. To address this issue, we surveyed physicians at the 5th Annual Meeting of the American Society for Laser Medicine and Surgery, May 1985. Forty‐two of the 226 physicians attending the meeting responded to the questionnaire about their experience with lasers in their practice. An average of 25 laser procedures per month were performed by the responding physicians, and 61.9% of them reported at least one complication. Of the complications reported in the survey, 33 occurred within the last 12 months for an overall rate of 2.7 incidents per 1,000 procedures performed. The most common complications reported were burns and scarring; however, bowel perforation and pneumothorax were among the more serious. The mean number of reported complications varied by the length and type of training in the use of the laser, with the lowest number of complications reported by respondents who had taken a training course lasting longer than 7 days within the last year. Our findings show that both minor and life‐threatening injury can be caused by the clinical use of medical lasers. Evaluation of the adverse effects of any medical technology, such as lasers, is needed to help guide recommendations for its safe use.
Thermal effects of lasers on dental tissues
Authors: Launay Y. , Mordon S. , Cornil A. , Brunetaud J. M. , Moschetto Y.
Published: March 2007

The thermal effects of Nd:YAG, argon, and CO2 laser beams are observed on enamel, dentin, and dental pulp by means of computerized infrared thermography and thermocouple. This study shows that the Nd:YAG laser beam deeply diffuses through the enamel and dentin to the pulp. The argon laser effects are inconsistent depending on whether the enamel surface is cleaned, but after cleaning, the superficial and deep temperatures are low. With the CO2 laser, the enamel and dentin surfaces reach very high temperatures, but only low temperatures are measured in the pulp chamber.
Endoscopic laser therapy for the treatment of malignant esophageal obstruction
Authors: Pietrafitta Joseph J. , Carstens Michael H. , Dwyer Richard M.
Published: March 2007

Malignant esophageal obstruction in 24 patients was treated using the neodymium:ytrium, aluminum, garnet laser. There were 15 males and nine females; the average age was 70.9 years. There were 17 adenocarcinomas and seven squamous cell carcinomas, with two of these being recurrent after radiation therapy. Tumor lengths ranged from 2.5–19.0 cm, with an average of 6.7 cm. The average energy delivered per centimeter of tumor was 6,309 joules for the squamous cell carcinomas and 5,598 for the adenocarcinomas. Energy delivered per treatment ranged from 3,152 to 70,527 joules. Total energy delivered per patient depended on the volume of tumor destroyed. Esophageal lumens increased from 3.4 to 16.7 mm, and 23 patients had their diets advanced, 22 to regular and one to soft solids. Reobstruction did not occur in patients who received adjunctive therapy after laser therapy. This consisted of chemotherapy in five, surgery in two, and radiation therapy in one. Complications consisted of aspiration pneumonia in three patients, including one who developed a tracheoesophageal fistula, and one documented and two suspected perforations. Hospital stay averaged 5.4 days overall and 3.5 days in those treated with the single‐session techniques. This increased to 8.0 days in patients with proven or suspected perforations. Endoscopic laser therapy is a safe and effective method for palliating esophageal cancer.
Effects of electrocautery, CO2 laser, and contact Nd:YAG laser scalpel on the healing of intestinal incision
Authors: Puolakkainen Pauli , Brackett Kim , Sankar M. Y. , Joffe Steven , Schröder Tom
Published: March 2007

Leakage after intestinal resection is a serious complication with a high mortality rate. A recent study claims that cutting the intestine with the CO2 laser improves the healing of intestinal anastomoses (Ferulano et al: Eur Surg Res 16:127–130, 1984). The present study was undertaken to analyze the effects of electrocautery, CO2 laser, and contact Nd:YAG laser on the healing of intestinal incisions.

Fifteen piglets were used and the cutting and reanastomosing were performed by using all cutting methods in each animal in randomized order. Resection sites were 50 cm, 100 cm, and 150 cm distal to the ligament of Treitz. On the seventh day the bursting pressures were measured for each anastomosis. They were 172 ± 17 mmHg for normal bowel segment and 133 ± 12, 135 ± 40, and 139 ± 17 mmHg for electrocautery, CO2 laser, and Nd:YAG laser, respectively.

There were no mortality, no anastomotic leaks, and no statistically significant differences in the bursting pressures, in histology, or in the healing of anastomotic sites, indicating that electrocautery, CO2 laser, and contact Nd:YAG laser scalpel can safely be used in the surgery of small intestine.
The contact Nd:YAG laser system in the treatment of bladder cancer: A preliminary report in 48 patients
Authors: Washida Hiroto , Watanabe Hideki , Sakagami Hiroshi , Sasaki Syoichi , Daikuzono Norio
Published: March 2007

A synthetic contact sapphire endoprobe attached to the quartz fiber of a neodymium:yttrium aluminum garnet (Nd:YAG) laser had been used in the transurethral treatment of bladder tumors. A total of 68 operations have been carried out in 48 patients. The contact probe was placed directly into the tumor under direct vision. Using 15‐20 watts of laser energy, the tumor blanched and underwent necrosis. The technique was easy to apply, and bleeding was minimal. Damage to the ureteral orifice and ureter in the bladder wall at repeat cystoscopy appeared less than with conventional electrocautery or noncontact laser treatment. The technique of contact Nd:YAG laser surgery will have an important role in the transurethral treatment of bladder tumors.
Effects of varying argon ion laser intensity and exposure time on the ablation of atherosclerotic plaque
Authors: Strikwerda Sipke , Bott‐Silverman Corinne , Ratliff Norman B. , Goormastic Marlene , Cothren Robert M. , Costello Ben , Kittrell Carter , Feld Michael S. , Kramer John R.
Published: March 2007

Using continuous wave (CW) argon ion laser light, a total of 253 laser exposures of varying power (1.5, 3, 5, 8 or 10 W) and duration (20–1,333 ms) were delivered to four segments of human atheromatous aorta obtained at autopsy. Exposure conditions were controlled by using an optically shielded laser catheter that provided a 500 μm spot of light of known power. Two thresholds for consistently reproducible ablation could be defined–an intensity threshold at 25.5 W/mm2 and a fluence threshold at 3.2 J/mm2. Above threshold, a fluence of 5.1 J/mm2 was found to produce the most efficient ablation, ie, removed the greatest volume (mm3) per energy delivered (J) compared to other fluence levels employed (p < 0.0001). Between aortic segments, however, considerable variability in efficiency (mm3/J) was observed, possibly owing to different optical properties and/or plaque composition. Low‐intensity laser radiation produced inconsistent ablation and extensive coagulation effects to surrounding tissue. When a fluence of 5.1 J/mm2 was constructed with a high‐intensity laser beam and a short exposure time, consistent and efficient tissue removal resulted without histologic evidence of coagulation necrosis.
Comparison of different lasers in terms of thrombogenicity of the laser‐treated vascular wall
Authors: Ragimov Sergey E. , Belyaev Andrey A. , Vertepa Igor A. , Dolgov Vladimir V. , Furzikov Nicolay P. , Akchurin Renat S. , Repin Vadim S. , Trubetskoy Andrey V.
Published: March 2007

The thrombogenic properties of the laser‐treated vascular wall are reported as quantitatively assessed on the basis of 33 experiments with peripheral canine vessel segments. Three types of surfaces, namely, (1) intact, (2) mechanically de‐endothelized, and (3) postlaser, have been simultaneously exposed to platelet‐enriched plasma in a sequentially organized artificial circulation system. Then the adherent platelets have been counted on the treated surfaces, and the relative thrombogenicity index has been calculated according to the equation T = (A1 – Aint)/(Ad – Aint), where Aint, Ad, A1 = the adherent platelet counts on intact, mechanically de‐endothelized, and laser‐treated surfaces, respectively. The following lasers have been evaluated: (1) Nd‐YAG, 1,060 nm, continuous wave, 4 W; (2) argon‐ion, 480 and 514 nm and argon‐ion, 350 nm, continuous‐wave, 1 W and 400 nW, respectively; (3) excimer XeCl, 308 nm, pulsed, 30 mJ per pulse, repetition rate 100 Hz; and also (4) the laser‐heated metal probe (2 mm diameter, Trimedyne, Nd‐YAG) 1,060 nm, 8 W. The thrombogenicity index values obtained were 83 ± 7, 72 ± 8, 57 ± 9, 63 ± 7, and 82 ± 9%, respectively. The differences between these values were statistically insignificant. The data are suggestive of the essential requirement of, at least, anticoagulant therapy after laser angioplasty irrespective of the laser type.
New laser hysteroscope for neodymium‐YAG endometrial ablation
Authors: Baggish Michael S.
Published: March 2007

A multichannel operating hysteroscope was developed for use with the Nd‐YAG laser. The telescopes measure 350 mm in length, with a 4 mm outer diameter (OD), and are available with 0° or 30° objectives. The operating sheath incorporates two isolated operating channels (2 mm OD) through which an Nd‐YAG quartz fiber and an aspiratory canula can be inserted simultaneously. The design of this instrument permits constant or intermittent aspiration of debris from the intrauterine milieu and very clear vision throughout the operative procedure. The entire cavity of the uterus may be flushed with the distending medium by injecting the liquid through the instillation channel and opening one of the two operating channels.
Long‐term investigations of laser‐assisted microvascular anastomoses with the 1.318‐μm Nd:YAG laser
Authors: Ulrich F. , Dürselen R. , Schober R.
Published: March 2007

Laser‐assisted microvascular anastomoses can be performed with the most diverse types of laser (Dujovny et al: 4th Annu Gen Sci Meet LANSI, 1986; Godlewski et al: World J Surg 10:329‐333, 1986; Gomes et al: Rev Hosp Clin Fac Med Sao Paulo 37:255, 1982; Quigley et al: Laser Surg Med 5:357–367, 1985; Quigley et al: Lancet 1:334, 1985; Quigley et al: Neurosurgery 18(3):292–299, 1986; Jain: J Microsurg 1:436–439, 1980; Jain: Lancet 2:816–817, 1984; Krueger and Almquist: Lasers Surg Med 5:55, 1985; Neblett et al: Neurosurgery 19(6):914–934, 1986; Schober et al: Science 232:1421–1422, 1986; Ulrich et al: 2nd Annu Gen Sci Meet LANSI, 1984; Ulrich and Bock: Optoelectronics in Medicine, Spring‐Verlag 418–423, 1986). However, postoperative complications in the form of thromboses and aneurysmatic sacs could be detected in 7–29.8% in longitudinal investigations. By conversion of the beam geometry (1.3 μm Nd:YAG laser, 200 μm light conductor) and use of three concentrically applied 10.0 backstitch sutures in 25 end‐to‐end anastomoses of the common carotid artery of adult albino rats 0.8–1.2 mm in diameter, early and late complications could be markedly reduced (12%).
Combination of laser plus 5‐fluorouracil for the treatment of extensive genital condylomata acuminata
Authors: Krebs Hans‐B.
Published: March 2007

Although laser is effective in the treatment of genital condylomata, patients with extensive lesions frequently require more than one treatment. The present study was undertaken to investigate whether the cure rate achieved by a single laser treatment could be improved by adding topical 5% 5‐fluorouracil (5‐FU). Twenty patients with extensive genital condylomata were treated with laser alone. Twenty patients comparable to the first group in age, number, size, and distribution of the condylomata were treated by laser and 5‐FU. The first application of 5% 5‐FU cream was carried out at the end of the laser treatment by the surgeon in the operating room. The patients were instructed to apply 5‐FU cream once weekly to the vulva and once every two weeks to the vagina by using an applicator filled to one‐third with 5‐FU cream. Seven patients (35%) without 5‐FU were found to have persistent condylomata at the first follow‐up examination eight to 12 weeks after the single laser treatment. Two additional patients were noted to have disease six and nine months after laser treatment. The combination of laser and 5‐FU failed in two cases (10%), both identified at the first visit. The difference is statistically significant (P <.025, chi‐square test). Two patients exposed to 5‐FU experienced chemical vulvitis. It is concluded that the combination of a single laser treatment and 5‐FU has acceptable side effects and results in a higher cure rate than a single laser treatment without 5‐FU.
Effects of different contact laser scalpels on skin and subcutaneous fat
Authors: Hukki Jyri , Krogerus Leena , Castren Maaret , Schroder Tom
Published: March 2007

The tissue effects of different Nd:YAG contact laser scalpels on pig skin and subcutaneous fat were studied using various power settings. Three different laser scalpels were tested: 0.2 mm nonfrosted (LR2), 0.6 mm nonfrosted (LR6), and 1.0 mm frosted (LRP10), using 3 different power settings (8 W, 14 W, 18 W). The tissue effects of a steel scalpel were used as reference. Incisions on pig loin (40/pig) were made at randomized sites. Specimens were taken at postoperative days 0 and 14. The depth of tissue damage was measured using a light microscope. The amount of time required for making each incision was recorded.

Significant differences between the LR2 and the LR6 were observed in the skin at 2 weeks (P <.05) at all power settings used, indicating superiority of the smaller scalpel for use in skin incisions. The LRP10 did not cause more tissue damage than did the LR6 in any of the power settings used.

In subcutaneous fat the smallest scalpel (LR2) caused significantly less tissue damage evident at 2 weeks postoperatively (P <.05) than did the other two laser scalpels, whereas the effects of the different power settings were minor.

The incision time in skin decreased by more than 50% when the power was increased from 8 W to 18 W for all laser scalpels studied.
Prograde versus retrograde endoscopic laser therapy for the treatment of malignant esophageal obstruction: A comparison of techniques
Authors: Pietrafitta Joseph J. , Bowers Gary J. , Dwyer Richard M.
Published: March 2007

The prograde and retrograde approaches to the treatment of malignant esophageal obstruction with the Nd:YAG, or neodymium: yttrium, aluminum, garnet, laser are compared. With the prograde technique, tumor destruction procceds from the proximal to the distal tumor margin. In retrograde treatment, the endoscope is passed to the distal tumor margin so that the treatment can proceed in the reverse direction, thereby completing therapy in a single treatment session. This is usually accomplished by passage of a guide wire down the biopsy channel of the endoscope, tumor dilatation, and then passage of the endoscope over the guide wire to the distal tumor margin, where laser destruction is begun. Twenty nonrandomly selected patients with malignant esophageal obstruction were studied. The first ten patients were treated with the prograde technique, the next ten with the retrograde technique. The two groups were similar with respect to age, sex, and tumor histologies. Patients treated retrogradely had narrower pretreatment lumens (average 2.3 vs. 4.1 mm) as well as longer tumor lengths (average 8.9 vs. 4.8 cm). The posttreatment luminal diameters were similar for each group: 18.0 mm for prograde; 16.3 for retrograde. In the retrograde group, therapy was completed in fewer treatments (1.6 vs. 2.9) and over a shorter period of time (3.6 vs. 7.8 days), despite the longer tumor lengths. All patients in both groups were able to tolerate a regular diet at the completion of therapy. The complication rate was low in both groups. It is felt that the retrograde technique (single session therapy) is the preferred method because it allows more‐rapid treatment without increased complications and thereby shortens hospital stay and reduces hospital costs.
Preliminary evaluation of a pulsed 2.15‐μm laser system for fiberoptic endoscopic surgery
Authors: Treat Michael R. , Trokel Stephen L. , Reynolds R. David , DeFilippi Vincent J. , Andrew James , Liu Jenn Ying , Cohen Martin G.
Published: March 2007

There is a need for lasers that are compatible with fiberoptic endoscopes and that provide greater cutting precision than currently can be produced by the widely used Nd:YAG (1.06μm) laser. Recently available lasers that operate in the 2‐μm region fill this need. This laser light energy can be transmitted by low OH–silica fibers and has much less tissue penetration than radiation at 1.06 μm. We have been evaluating a prototype solid state laser system that produces pulses of 2.15 μm light that is delivered by a silica based fiberoptic delivery system with negligible transmission losses. This system is based on a thuliumholmium‐chromium doped YAG (Tm‐Ho‐Cr: YAG) rod that lases at 2.15 μm. The laser does not require cryogenic cooling, toxic gases, or custom utilities and should be practical in a clinical environment. In vivo animal testing of this laser confirms that it provides greater ablating precision than does the Nd:YAG laser at 1.06 μm.
Laser lithotripsy: A review of 20 years of research and clinical applications
Authors: Dretler Stephen P.
Published: March 2007

Four new technologies have transformed the treatment of urinary calculi: electrohydraulic lithotripsy, ultrasonic lithotripsy, extracorporeal shock wave lithotripsy, and laser lithotripsy. Initial attempts to ablate urinary calculi by continuous wave CO2, ruby, and Nd‐YAG lasers failed because of excess thermal injury and inability to pass the laser energy via a flexible fiber. Basic laboratory studies then demonstrated that short pulsed laser energy absorbed by the calculus resulted in fragmentation. The parameters that produced optimal urinary calculus fragmentation were found using the flashlamp pumped tunable dye laser, with the following parameters: wavelength: 504 nm; pulse duration: 1 μsec; fiber: 250 micro silica‐coated quartz; repetition: 5–20 Hz. Use of pulsed dye laser caused no tissue damage. The mechanism of fragmentation is light absorption, plasma development, and repetitive acoustic shock wave action with resultant fragmentation. The techniques for application of laser to calculi have been successful, and new, miniature instruments have been developed. Laser lithotripsy is a successful method for fragmenting ureteral calculi. The small caliber of the laser fiber makes this method useful for treating calculi in narrow, tortuous ureters; impacted calculi; distal calculi in ureters that cannot be dilated, via the percutaneous route for stones in calyces or impacted in the upper ureter. Investigations are continuing to optimize fragmentation of harder calculi and to use laser fragmentation within the kidney. Laser lithotripsy may also be used to fragment biliary calculi.
Laser balloon angioplasty: Effect of exposure duration on shear strength of welded layers of postmortem human aorta
Authors: Jenkins Ronald D. , Sinclair I. Nigel , Anand Raj K. , James Leslie M. , Spears J. Richard
Published: March 2007

Laser Balloon Angioplasty (LBA) is a technique that may improve the results of balloon angioplasty by thermally sealing arterial dissections and reducing elastic recoil. To define the relationship between laser‐exposure duration and the strength of thermal welds made between separated layers of arterial wall, 360 1‐cm discs of human postmortem aorta were lased for six different exposure intervals at three different temperature ranges, comparing shear strength of thermal welds in the different groups. Twenty discs were lased to achieve plateau adventitial temperatures of 95°C–104°C (group A), 105°C–114°C (group B), or 115°C–124°C (group C) at each of the exposure periods (5, 10, 15, 20, 25, and 30 sec). A 400‐μm fiberoptic coupled to a 1.06 μm continuous wave neodymium:YAG laser was placed perpendicularly 8 mm above the luminal surface of each disc, which had been split midway between the intimal and adventitial surface and reapposed. Mean laser energy ranged 78–378 J delivered in a decremental stepwise fashion to achieve quickly and maintain the target plateau tissue temperature. Mean weld strength increased in relation to both achieved tissue temperature and laser‐exposure duration, with at least 10 sec necessary, at temperatures greater than 95°C, for reliable thermal welding. Laser exposure for greater than 20 sec provided no statistical increment in weld strength. In the anticipated clinical performance of LBA, these data suggest that when thermal fusion of disrupted arterial tissues is desired, a laser‐exposure duration of 10–20 sec is optimal.
Laser instrumentation: A microtenaculum for laser tissue fusion
Authors: White John V.
Published: March 2007

Precise tissue apposition and edge eversion are essential for tissue fusion with the CO2 laser. A microtenaculum has been designed to accomplish this without the placement of horizontal mattress stay sutures. This instrument permits tissue orientation and approximation for primary laser fusion as well as for the repair of small gaps present after initial welding.
Molecular, cellular, and tissue responses following photodynamic therapy
Authors: Gomer Charles J. , Ferrario Angela , Hayashi Naganobu , Rucker Natalie , Szirth Bernard C. , Murphree A. Linn
Published: March 2007

Photodynamic therapy (PDT) is being utilized in the treatment of a wide variety of malignant tumors. Results using PDT have been encouraging, and controlled clinical trials are currently being performed. The procedure exploits both the tumor‐localizing and ‐photosensitizing properties of hematoporphyrin derivative or its purified component, Photofrin II. When this porphyrin mixture is administered systemically, it is retained preferentially in tumor tissue as compared to surrounding normal tissue. Localized tumor destruction induced by PDT results from the photochemical generation of cytotoxic oxygen species within the tumor. This review will provide a summary of historical and current research pertaining to molecular, cellular, and tissue responses induced by PDT. Emphasis is placed on information related to the chemistry of current photosensitizers, subcellular targets, preclinical treatment parameters, and clinical responses following PDT.
Comparison of local tumor recurrence following excision with the CO2 laser, Nd:YAG laser, and argon beam coagulator
Authors: Lanzafame Raymond J. , Qiu Kang , Rogers David W. , Naim John O. , Caldwell Fred C. , Hall Freddy Perry, Darline , Hinshaw J. Raymond
Published: March 2007

This study compares the incidence of local tumor recurrence following primary excision with the CO2 laser, Nd:YAG laser (contact), Argon Beam Coagulator, or electrocautery. One hundred eight Fisher 344 rats with R3230AC mammary tumors (1.6 ± 0.04 [SD] cm diameter) were used. All animals were randomized into groups of similar tumor size. In groups C and CS, excision was performed with a Sharplan 1060 CO2 laser (TEMoo, 25 W, continuous wave [CW], 0.2‐mm spot size). Wounds in group CS were “sterilized” (0.5‐mm spot size, 25 W, CW) by gently heating the wound without causing blanching or charring. In group N, a 0.4‐mm contact Laser Blade± and a Cooper 8000 Nd:YAG laser at 20 W CW was used. In groups SA1 and SA2, tumors were excised with the scalpel, and hemostasis and wound “sterilization” were accomplished with the Bard System 6000 Argon Beam Coagulator (ABC) at 40 W and 4 liters/min argon gas flow in SA1 and 12liters/min in SA2. In group E, excision was accomplished at 40 W blend mode, 10 W spray mode. In group EA, excision was accomplished at 60 W cutting current, and hemostasis was achieved with the ABC. The animals were examined for evidence of recurrence for 34 days postoperatively. Mortalities were excluded from analysis. The incidence of recurrence was 11/14 (79%) in C, 6/16 (38%) in CS, 10/14 (71%) in SA1, 6/13 (46%) in SA2, 6/15 (40%) in N, 7/10 (70%) in EA, and 3/15 (20%) in E. Group E is statistically different (P < .01) from groups EA, C, and SA1. Group C was different (P < .01) from groups E, CS, and N. These results demonstrate an inverse relationship between tumor recurrence and local thermal effects at the surgical site. The ABC did not increase tumor recurrence. Contact YAG surgery was similar to CO2 laser excision and “sterilization.” An attempt to study the influence of gas flow and pressure on local tumor recurrence and metastases should be made.
Effects of blood flow on laser probe temperature in human arteries
Authors: Silverman Steven H. , Khoury Adib I. , Abela George S. , Seeger James M.
Published: March 2007

Laser recanalization using metal capped fibers occurs by thermal vaporization of occluding plaque. However, little is known about the effects of blood and flow on the temperature of the laser probe or the arterial wall during lasing. To study this, probe and arterial wall temperatures were measured while a metal capped fiber, activated by an argon laser, was held stationary in a stenotic human peripheral artery. Arteries were perfused with saline and blood, and flow was varied from 0 to 140 cc/min. Probe temperatures were significantly higher in blood than in saline. However, the increased probe temperature achieved in blood was not transferred to the arterial wall. Increasing flow decreased probe temperature in both media, but again arterial wall temperatures were minimally affected. Thus, the presence of blood and flow may significantly affect heat generation and heat transfer during arterial recanalization using metal capped fibers.
Cellular effects of the pulsed tunable dye laser at 577 nanometers on human endothelial cells, fibroblasts, and erythrocytes: An in vitro study
Authors: Glassberg Edward , Lask Gary P. , Tan Elaine M. L. , Uitto Jouni
Published: March 2007

The 577‐nm flashlamp‐pumped tunable dye laser pulsed at 450 μs is rapidly becoming the treatment of choice for removal of portwine stains and other vascular ectasias. In this study, we examined the mechanisms of vessel destruction by determining the effects of laser irradiation on three types of primary target cells–erythrocytes, endothelial cells, and fibroblasts. Human endothelial cells and fibroblasts in microwell plates were irradiated at various energy densities with the laser, after which several aspects of cellular biology were determined, including (1) viability of cells by trypan blue exclusion test; (2) cell proliferation by [3H]thymidine incorporation; and (3) rate of protein synthesis using [3H]leucine incorporation as a marker. In endothelial cell cultures, both [3H]thymidine and [3H]leucine incorporations were inhibited at energy levels of 5–12 J/cm2 (P < 0.01). In fibroblast cultures, cell proliferation was similarly inhibited, while supratherapeutic energy density (⩾12 J/cm2) was required for inhibition of protein synthesis. The laser energy in the range of 5–8.5 J/cm2 had no effect on cell viability. Erythrocytes as target cells for laser energy demonstrated rapid, dose‐dependent lysis, as determined by release of free hemoglobin into culture medium. Addition of erythrocytes into a coculture with endothelial cells abolished the direct inhibitory effect noted in cultures when endothelial cells were present alone. The results of the latter experiment imply that erythrocytes are the primary target cell absorbing the laser energy at 577 nm. However, direct laser effects on endothelial cells may also contribute to the mechanisms of ablation of the vascular ectasias by the tunable dye laser at 577 nm.
Laser‐Assisted intestinal anastomosis
Authors: Vlasak Jerry W. , Kopchok George E. , White Rodney A.
Published: March 2007

Laser‐assisted tissue fusion has been investigated as a new technology to enhance the healing of soft tissues. Laser fusion of intestinal anastomoses shows promise as a method to obtain primary healing while eliminating a foreign‐body reaction associated with the sutures. This paper reviews the experimental data that are available regarding laser‐assisted intestinal anastomoses and summarizes our experience using the CO2, Nd:YAG, and argon lasers to form fusions in small bowel.
Argon laser treatment of urethral stricture and vesical neck contracture
Authors: Adkins William C.
Published: March 2007

The physical characteristics of the argon laser wavelength allow a precise incision with excellent hemostasis and negligible heating of adjacent tissues resulting in less scarring. These qualities are used to advantage in the treatment of strictures. The argon laser was used to perform 13 internal urethrotomies and ten vesical neck incisions. The operative method used is similar to optical internal urethrotomy. The argon probe incises hemostatically, reducing the need for extensive fulguration of tissues at the operative site and thereby reducing the tendency for more scar tissue to form and compromise the operation. The same hemostasis reduces the need for postoperative indwelling urethral catheterization. Utility of the argon device in most instances allows treatment to be conducted on an outpatient basis without general anesthesia and without use of postoperative urethral catheters, yielding an effective, cost‐saving therapy.
Anastomosis of bypass grafts using a low‐powered CO2 laser
Authors: Frazier O. H. , Shehab S. Anne , Zirl Robert , Radovancevic Branislav , Nakatani Takeshi , Bossart Mattie I. , Parnis Steven M.
Published: March 2007

The purpose of this study was to evaluate the feasibility of using a low‐powered CO2 laser to perform end‐to‐side anastomoses of bypass grafts. The internal jugular veins of 13 domestic swine were removed and used as grafts to bypass their ligated carotid arteries. Each end of the vein graft was apposed to the artery with four to six temporary stay sutures, and a waveguide delivery CO2 laser with a power density of 900 mW/mm2 was used to perform the anastomoses, after which the sutures were removed. The animals were sacrificed postoperatively at five time intervals: 2 to 4 hours, 5 days, 1 month, 3 months, and 5 months. Of the 10 anastomoses studied at 2 to 4 hours, 70% were fully patent, none thrombosed, and 30% disrupted. Of the 16 anastomoses studied between 5 days and 5 months postoperatively, 88% were patent, 12% thrombosed, and none disrupted. None of the animals developed aneurysms at any stage of this investigation. Histologic analysis of acute studies revealed thermal damage such as charring of tissue, unraveling of the collagen fibrils, and the formation of microvacuoles. Within 3 months, the anastomotic sites showed localized healing with intimal fibromuscular proliferation and dense fibrous tissue. Good apposition of tissue was found to be of great importance in achieving patency of vessels in this procedure.
Effect of low‐energy laser irradiation on colony formation capability in different human tumor cells in vitro
Authors: Marchesini Renato , Dasdia Teresa , Melloni Elsa , Rocca Emilio
Published: March 2007

Fibroblasts and lymphocytes are the most widely used cells for studying the so‐called biostimulative effect of low‐power laser in vitro. In contrast, stimulation of cancer cells by laser light has not been investigated extensively. The present study attempted to evaluate whether or not human tumor cells could exhibit an increase in colony‐forming capability following low‐watt laser irradiation. LoVo and HT29 (colon carcinoma), MCF7 (breast carcinoma), M14 and JR1 (malignant melanoma) cell lines were irradiated at different doses of light delivered from an argon or an argon‐dye laser. Radiant exposures between 4.2 and 150 kJ/m2 at irradiances ranging from 35 to 500 W/m2 were delivered. Results were mixed. Of the 41 experiments performed, five showed a significant statistical increase in the number of colonies (P< 0.05), whereas three showed a decrease (P < 0.05). Nevertheless, the trend of most data was toward an increase in colony formation, and Wilcoxon's signed‐ranks test suggested that light increases tumor cell culture growth (P < 0.03).
In vitro photosensitization I. Cellular uptake and subcellular localization of mono‐L‐aspartyl chlorin e6, chloro‐aluminum sulfonated phthalocyanine, and photofrin II
Authors: Roberts W. Gregory , Berns Michael W.
Published: March 2007

The mechanisms of cellular uptake, subcellular localization, and cellular retention kinetics of the photosensitizers photofrin II (PfII), mono‐L‐aspartyl chlorin e6 (MACE), and chloro‐aluminum sulfonated phthalocyanine (CASPc) are reported in this paper. Each photosensitizer's cellular uptake mechanism was determined by preferentially inhibiting endocytosis by chilling cells to 2°C, while allowing diffusion across the membrane. Subcellular localization was studied by computer‐enhanced low‐light level video fluorescence microscopy, while flow cytometry was used to determine uptake and retention kinetics. The results indicate that PfII enters the cell primarily by diffusion across the membrane, whereas MACE and CASPc enter the cell through endocytosis.
Acoustic and plasma‐guided laser angioplasty
Authors: Bhatta Krishna M. , Rosen David I. , Dretler Stephen P.
Published: March 2007

The feasibility of using acoustic and plasma‐guided laser (APGL) for angioplasty was studied in vitro. A flashlamp‐pumped tunable dye laser operating at a wavelength of 504 nm (coumarin green) was used as the laser source. Acoustic signals were recorded with a hydrophone, which has a useful frequency response of up to 350 kHz. Plasma optical emissions were transmitted retrograde along the laser fiber and reflected through a beam splitter to an optical detection system consisting of a series of spectral filters (to transmit plasma radiation from 380 nm to 440 nm and block any 504 nm laser light) and a photomultiplier tube.

Measurements of the acoustic and the plasma optical signals were obtained from blood, atheromatous plaque, and normal arterial wall. Results of monitoring show that it is possible to know without direct vision whether the laser energy is being discharged in the lumen (blood), on the normal arterial wall, or on the atheromatous plaque. Blood produced strong acoustic signals but no plasma signals; plaque produced strong plasma and strong acoustic signals. Neither plasma nor significant acoustic signals were produced by the normal arterial wall. These distinctions may allow clinical laser ablation of plaque to be performed with fewer complications.
Light distributions in artery tissue: Monte Carlo simulations for finite‐diameter laser beams
Authors: Keijzer Marleen , Jacques Steven L. , Prahl Scott A. , Welch Ashley J.
Published: March 2007

Finite‐width light distributions in arterial tissue during Argon laser irradiation (476 nm) are simulated using the Monte Carlo method. Edge effects caused by radial diffusion of the light extend ±1.5 mm inward from the perimeter of a uniform incident beam. For beam diameters exceeding 3 mm the light distribution along the central axis can be described by the one‐dimensional solution for an infinitely wide beam. The overlapping edge effects for beam diameters smaller than 3 mm reduce the penetration of the irradiance in the tissue. The beam profile influences the light distribution significantly. The fluence rates near the surface for a Gaussian beam are two times higher on the central axis and decrease faster radially than for a flat profile. The diverging light from a fiber penetrates tissue in a manner similar to collimated light.
Picosecond optical breakdown: Tissue effects and reduction of collateral damage
Authors: Zysset Beat , Fujimoto James G. , Puliafito Carmen A. , Birngruber Reginald , Deutsch Thomas F.
Published: March 2007

The effects of picosecond laser‐induced optical breakdown on tissue were investigated using high‐intensity 40 ps Nd:YAG laser pulses at 1.06 μm. Tissue damage was evaluated using the corneal endothelium in vitro as a model system. Systematic studies were performed to determine the scaling of the tissue damage and damage range with pulse energy. For suprathreshold lesions, the radius of the damage zone varies as the cube root of the pulse energy, in agreement with simple physical scaling laws. A minimum damage range of less than 100 μm was observed for pulse energies of 8 μJ. Damage morphology was investigated by scanning electron microscopy. Three different damage patterns were observed: cell damage, cell removal, and rupture of Descemet's membrane. Different irradiation geometries were used to study damage mediated by either the shock wave or the cavitation bubble. Comparative studies using 10 ns pulses demonstrated that picosecond pulses yielded a significant reduction in collateral tissue damage.
Laser dentistry: Root canal diagnostic technique based on ultraviolet‐induced fluorescence spectroscopy
Authors: Pini Roberto , Salimbeni Renzo , Vannini Matteo , Cavalieri Stefano , Barone Roberto , Clauser Carlo
Published: March 2007

A diagnostic technique to detect residual tissues at different levels of the root canal during an endodontic treatment is presented. The diagnostic system is based on ultraviolet‐induced fluorescence spectroscopy and uses suitable optical fibers for local delivery of excitation light and to collect back fluorescence spectra. Spectra of root canal tissues have been obtained from split teeth by labeling with a fluorescent solution. Residual tissue can be discriminated in respect to healthy dentin because of their different spectral responses: the spectral shape of the first response shows a clear peak at 530 nm because of a selective absorption of the fluorescent dye, whereas for the second response, the spectral curve monotonically increases toward ultraviolet wavelengths with no particular structure. This technique has been tested on unsplit teeth simulating operative conditions. A compact spectroscopic system has been devised that can be easily integrated in an excimer laser system to perform residual tissue detection during laser cleaning of the canals.
Reflectance during pulsed holmium laser irradiation of tissue
Authors: Nishioka Norman S. , Domankevitz Yacov
Published: March 2007

Although generally ignored in considerations of laser ablation of tissue, reflectance of laser light from tissue during laser‐induced ablation is a potentially important factor in determining ablation efficiency because it determines the amount of laser light coupled into the target. To determine the significance of reflectance changes induced by laser irradiation, we examined the reflectance of liver samples during pulsed holmium laser ablation by placing the target at one focus of an ellipsoidal reflector and a detector at the other focus. The temporal behavior, total reflectance, and effect of multiple pulses were examined. Tissue reflectance as large as 50% was observed during holmium laser irradiation but depended upon laser radiant exposure and number of laser pulses. These measurements suggest that changes in the optical properties of the target during ablation are important and should be considered in detailed modeling of the ablation process.
Should there be a formal mechanical‐optic‐electronic biomedical‐engineering program?
Authors: Goldman Leon
Published: March 2007

To progress in the development of laser medicine and laser surgery, multidisciplinary efforts are required. One important phase in its development is the laser biomedical engineering program being offered following the basic laboratory research. Some of this type of programming is present today, but more development is needed for a formal program offering crossfertilization between engineering and medical uses. Therefore, a formal program is being proposed, which will be reviewed by mixed groups over a period of time. A final recommendation will indicate whether to go ahead with this revision of the program, to wait for further development of the program, or to maintain the status quo. The relationship of technical training for technicians in laser biomedical engineering is also reviewed.