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The feasibility of welding thin-walled microvessels by laser has been established. This report summarizes our experience using laser welding to repair thick-walled, high-pressure, 4 to 8-mm canine arteries using CO2, Nd:YAG, and argon lasers. The CO2 laser did not produce seals that could withstand arterial pressure. Nd:YAG laser welds were initially successful, but the majority failed within 20 to 40 minutes. The argon laser uniformly sealed 2-cm-length arteriotomies that healed rapidly within 4 to 6 weeks and had less foreign body response compared to sutured controls. Laser welding may represent an alternative for repair of small- and large-diameter vessels with several advantages compared to conventional suture techniques.

Recent evidence suggests that low-energy lasers, such as an He-Ne laser, might stimulate wound healing. In this review we are summarizing our recent observations indicating that low-energy lasers enhance collagen gene expression both in skin fibroblast cultures in vitro, as well as in animal models of wound healing in vivo.

Clinical observations have suggested that low-energy lasers might stimulate wound healing. To understand the mechanism of the biostimulation, we previously examined the effects of low-energy lasers on collagen production by human skin fibroblasts and reported an increase of collagen synthesis in vitro. To examine the effects of low-energy lasers in vivo, hairless mice were experimentally wounded, sutured, and subjected to laser irradiation by a helium-neon laser with a power output of 1.56 mW and an energy fluence of 1.22 Joules/cm2. Experimental wounds were subjected to laser treatment every other day for 2 months; control wounds remained untreated. Specimens from the wounds were then examined for histological findings, tensile strength, and total collagen content. Results demonstrated a considerable improvement in the tensile strength of the laser-irradiated wounds at 1 and 2 weeks. Furthermore, the total collagen content was significantly increased at 2 months when compared with control wounds. These results suggest a beneficial effect of the helium-neon laser on wound healing in vivo.

Of the patients with cecal diverticulitis, 24 to 50% are below the age of 30, and such cases are usually misdiagnosed preoperatively as appendicitis. Two young patients with cecal diverticulitis were diagnosed preoperatively by barium enemas. The barium enemas correctly identified the extent of the disease. Treatment was tailored to the clinical and roentgenographic findings with both patients requiring elective colon resections.

Previous studies have indicated that laser can selectively affect the biological functions of cells. In the present study, the role of a thermal component in laser-induced alterations in the biology of human skin fibroblasts was examined. Cells were cultured on 96-well tissue culture plates, subjected to treatment with the Nd:YAG laser (wavelength 1,064 nm), and the temperature of the medium was monitored by a microprobe connected to a telethermometer . For comparison, parallel cultures were heated to the same temperatures by tungsten-halogen lamp. The cell cultures were analyzed for collagen synthesis by incubating the cultures with [3H]proline, and the collagen production was assayed by the synthesis of nondialyzable [3H]hydroxyproline. The rate of DNA replication was also determined by measuring the uptake of [3H]thymidine. A marked decrease of collagen production and thymidine incorporation was noted in the cultures subjected to Nd:YAG laser. No such decreases were noted in cultures heated to the corresponding temperatures by tungsten-halogen lamp. The results thus indicate that the biochemical alteration caused by the Nd:YAG laser in human fibroblast functions cannot be explained on the basis of thermal effects.

Pig skin was treated with the Nd:YAG laser at 1,060 nm or electrocautery, at energy densities of 649 +/- 20 J/cm2 and 612 J/cm2, respectively. Biopsies of treated areas and of normal skin were performed at 7, 14, and 60 days after treatment and processed for histology, electron microscopy and biochemical assays. Wound healing, as shown histologically, was similar in both treated groups. Depth of injury appeared to reach reticular dermis at day 7 in each treated group. However, thermal burn was more destructive of regular collagen, whereas the laser appeared to damage deep dermal blood vessels without destroying surrounding connective tissue. Biochemical assays revealed increased collagen production and increased collagenolytic activity 7 days after laser injury. However, by day 60, there was a reduction in total collagen content in laser treated skin below that of normal skin, which correlated with decreased collagen synthesis and unchanged collagenolytic activity. In burn specimens there was an initial decrease in total collagen content which reverted to normal by day 60. Active collagen degradation occurred at all 3 time points, but a marked increase in synthetic activity occurred as the burn scar was laid down. Laser treatment resulted in reduction of the amount of collagen below that in burn scarred or normal skin, suggesting that classical scar formation may be inhibited. These results indicate that the Nd:YAG laser may be useful for the treatment of keloids and hypertrophic scars.

To determine the effects of laser irradiation upon human coronary atherosclerotic disease, coronary plaques were extracted from fresh human cadaver hearts. Seventy-four diseased artery samples were sectioned either transversely or longitudinally and subjected to laser treatment from argon-ion and carbon dioxide sources. The laser beam affected vaporization and patency in fibrous, lipoid, and calcified plaques as observed histologically. Calcified blockage showed greater extent of charred remnants following controlled thermal injury than did fibrous or lipoid obstructions. The area and depth of penetration varied directly with intensity and duration of photoirradiation and inversely with the density of the atherosclerotic tissue. This study supports further research work on the use of lasers to effect relief of atherosclerotic obstructions.

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 proceeds 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.

We report a series of patients with severe radiation injury treated with endoscopic laser photocoagulation. Eight patients with recurrent lower gastrointestinal bleeding secondary to procosigmoiditis were treated with endoscopic Nd:YAG laser therapy. Patients were followed for an average of 21.7 months after the first laser treatment. Average transfusion requirements and hospital admissions per patient-month were 0.93 and 0.27, respectively, in the prelaser period and 0.18 and 0.06, respectively, in the entire period following the first laser treatment. A total of 26 laser treatments were performed. There were three major (prolonged ileus) and one minor (pain) complication. We conclude that endoscopic Nd:YAG laser photocoagulation is a safe, effective, and lasting treatment in severe, symptomatic radiation injury of the lower gastrointestinal tract.

Skin incisions 6 mm in length were made on the backs of hairless mice. Control wounds were closed with interrupted 5-0 Prolene sutures, and experimental wounds were approximated and closed by laser welding using a Nd: YAG laser. The wounds were examined daily, and specimens were excised at weekly intervals for histopathologic study, transmission electron microscopy, tensile strength determination, and type I collagen-specific messenger ribonucleic acid measurements. The laser-welded wounds demonstrated rapid healing. Histologic study showed a functional scar tissue at day 7 and a minimal residue of the original wound at day 14. Tensile strength of the control and experimental wounds was similar at all time points. The levels of collagen-specific messenger ribonucleic acid were significantly higher in the sutured group in comparison with the laser group or with normal control skin. This study suggests that laser welding might have advantages over suturing, since the former is sterile and nontactile, does not require introduction of foreign material into the wound, and provides subjectively improved cosmetic results.

Human skin fibroblasts were subjected to treatment with a Neodymium:YAG laser at 1060 nm with varying levels of energy determined by a reproducible method of dosimetry. DNA synthesis in the cells was measured by the incorporation of [3H]thymidine, and collagen production was monitored by the synthesis of nondialyzable [3H]hydroxyproline after incubation of cells with [3H]proline. Using energy levels equal to 1.7 X 10(3) J/cm2, a significant reduction in DNA synthesis was noted, while the cells remained viable as tested by the trypan blue exclusion test. With energy levels higher or equal to 2.3 X 10(3) J/cm2, the suppression of DNA synthesis was accompanied by cell nonviability. The collagen production, when measured immediately following the treatment with 1.7 X 10(3) J/cm2, was markedly reduced, and similar effects were observed with higher energy levels. However, when the cells were tested for collagen production at 20 hours following laser treatment, there was a significant decrease in collagen production at energy levels as low as 1.1 X 10(3) J/cm2, a dose that did not affect DNA synthesis or cell viability. Thus, the results indicate that the Nd:YAG laser can selectively suppress collagen production without affecting cell proliferation. These observations suggest that laser treatment could potentially be used to reduce collagen deposition in conditions such as keloids and hypertrophic scars.

The use of lasers in medicine and surgery has increased slowly-its effectiveness based on trial-and-error clinical experience. Very little comprehensive data has been published that scientifically presents dosage, energy, absorption, and comparisons between types of lasers. Our laboratory has developed a method for taking the guesswork out of laser dosage using scientific data to optimize therapy and give reproducible responses. Experiments were conducted using an argon laser, a neodymium: YAG laser, and a broad-band infrared light source. This preliminary study uses a beam scan technique, which for the first time permits accurate measurement of the laser intensity incident on tissue. Therefore, this protocol allows the standardization of dosage measurements with good experimental reproducibility in biological models. By using this accurate method of measuring the intensity delivered to pigskin, we are able to reproduce for the first time similar histological damage with the different energy sources.

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.

• Malignant esophageal obstruction in patients with carcinoma of the esophagus and adenocarcinoma of the distal esophagus usually indicates far-advanced disease. Palliative therapy with the neodymium—yttrium, aluminum, garnet laser has been proposed as an alternative to more invasive procedures that do little to improve the quality of life or prolong survival. Fifteen patients were treated with endoscopic laser therapy. A previously described technique was used to treat the first ten patients; the remaining five were treated with a single-session therapy method. This new technique allowed more rapid completion of therapy (1.4 treatments over 2.2 days vs 2.9 treatments over 7.8 days) without sacrificing safety. Single session therapy using this laser is recommended as the treatment of choice in patients with carcinoma of the esophagus with obstruction that is surgically or radiotherapeutically incurable. ( Arch Surg 1986;121:395-400)

The use of lasers in gastrointestinal diseases is becoming more commonplace, yet there are several major issues about which there is not unanimous agreement. I thought it would be valuable to review with the discussants some of the major undecided issues regarding the use of lasers today. Through the course of the following discussion we will address the issues listed below: 1) which endoscope should be used and for what reason, 2) where should the endoscopic laser procedure be performed, 3) what type of anesthesia should be used, 4) which bleeding lesion should be treated, which bleeding lesion should not be treated, 5) in the case of the recently bleeding ulcer that has ceased bleeding under what circumstances is laser therapy indicated, 6) how do you train endoscopists to perform laser therapy, 7) should there be any limitations upon who should be allowed to purchase lasers, 8) are controlled trials necessary for the treatment of acute gastrointestinal bleeding, 9) is further animal work with lasers necessary and if so in what areas, 10) which gastrointestinal malignancies are amenable to laser treatment and which of these should be treated.

This study compared the histology, biochemistry, tensile strength, and extensibility of Nd:YAG laser-welded and sutured venotomies. Two-centimenter-length bilateral canine femoral or jugular venotomies were evaluated with one vessel (control) closed with interrupted 6-0 polypropylene sutures, and the contralateral vessel (experimental) welded with the Nd:YAG laser (1 W power and 30- to 40-sec exposure). Specimens were removed and examined immediately after fashioning (t0) and at 1, 4, or 5 weeks post-operatively to compare the progression of healing. Histologic examination of the 4- and 5-week sutured wounds had granulomatous reaction around the sutures with areas of excessive collagen accumulation. In contrast, the laser-welded wounds had minimal inflammatory response, near normal collagen content, and minimal residual disorientation and break in the elastic fiber continuity. The rate of collagen synthesis in laser-welded wounds was approximately twice that of sutured wounds at 1, 4, and 5 weeks, and correlated with increased tensile strengths of lasered wounds. The extensibility of the 5-week specimens was 0.19 for sutured and 0.29 for laser-welded wounds as compared to 0.29 for normal vein. These preliminary data suggest that laser welding of venotomies may have several advantages over conventional suture techniques.

Fiberoptics are utilized in medicine by fields which have classically used light for either diagnosis or treatment. The specialities that have adopted the use of lasers have included the light for treatment and diagnosis group and those who have a problem with hemostasis in their treatment regimen. Table 1 lists the specialities which utilizes the diagnostic applications of fiberoptics. The diagnostic applications can be divided into the use of coherent fiber bundles for visualization and incoherent fiber bundles for illumination. Endoscopy is the introduction of a tube containing both coherent and incoherent fiber bundles into body orifices either natural or man made. Peritonoscopy inspects the abdomen through a small incision and enables the physician to observe from the reproduction tract in the pelvis to the dome of the liver. Gastrointestinal endoscopy uses these techniques through different instruments to explore the upper tract through the mouth or the lower tract through the anus. Pulmonary endoscopy called bronchoscopy enters the respiratory tract through the mouth. Urology investigates the bladder in cystoscopy through the urethra. All these diagnostic applications can also take biopsies through these instruments for diagnoses of anatomical abnormalities visualized through the endoscopic instruments.© (1978) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

• We investigated the histologic and biochemical effects of carbon dioxide and neodymium (Nd)-YAG laser welding on the healing of venotomies. Ten canine femoral venotomies 2 cm in length were approximated and welded with 10 600-nm wavelength, 1-W power over 20 to 25 s for CO 2 laser, and 1060-nm wavelength, 1-W power over 30 to 40 s for Nd-YAG laser. On removal at one to three weeks, all veins (4/4 welded by CO 2 and 6/6 by Nd-YAG) were patent without hematomas. Histologic and biochemical analyses of the venous tissues demonstrated active healing at the venotomy sites. We conclude that the CO 2 and Nd-YAG lasers can be used successfully to weld venotomies and may provide an alternative to conventional suture techniques for repair of vascular lesions. ( Arch Surg 1986;121:905-907)

A unique family with a distinct syndrome of adenomatous colonic polyps and sebaceous cysts without osseous or soft tissue abnormalities is presented. One member had benign gastric polyps limited to the upper half of the stomach and another had a medulloblastoma of the cerebellum. A histologic feature in the colon of the propositus was the presence of atypical epithelium in flat mucosa as well as in the colonic polyps.

In 1971, a surgeon named Goodale at the University of Minnesota described the first application of a laser to the gastrointestinal tract.1 He performed open surgery and using a CO2 laser to coagulate diffuse bleeding from the stomach in an attempt to avoid gastric resection. This article inspired other people in the world to look to the possibility of the endoscopic delivery of laser energy for coagulation.

Various laser modalities are currently in extensive use in dermatology and plastic surgery, particularly for treatment of vascular and pigmented lesions. A relatively new area of laser utilization involves the possible biologic effects of the lasers. In this overview, we are summarizing our recent studies, which indicate that lasers at specific wavelengths and energy densities modulate the connective tissue metabolism by skin fibroblasts both in vitro and in vivo. Specifically, the neodymium-yttrium-aluminum-garnet (Nd: YAG) laser was shown to selectively suppress collagen production both in fibroblast cultures and in normal skin in vivo, thus suggesting that this laser modality may be useful for the treatment of fibrotic conditions such as keloids and hypertrophic scars. Furthermore, two low-energy lasers, helium-neon (He-Ne) and gallium-arsenide (Ga-As), were shown to stimulate collagen production in human skin fibroblast cultures, suggesting that these lasers could be used for enhancement of wound healing processes. These experimental approaches illustrate the future possibilities for applying lasers for the modulation of various biologic functions of cells in tissues and attest to the potential role of lasers in the treatment of cutaneous disorders.

• An argon-ion laser, coupled to a flexible fiberoptic endoscope, was used to photocoagulate experimentally produced bleeding gastric ulcers in dogs. Argon-ion laser phototherapy rapidly and effectively achieved hemostasis in all bleeding ulcers. Bleeding arteries up to 2 mm in diameter were photocoagulated. Intact normal gastric mucosa was exposed to laser energy for varying periods of time to determine if transmural photothermal injury occurred. Exposure for greater than 15 seconds at 1.0 w of throughput power caused microscopical evidence of transmural injury. Healed, laser-treated ulcers could not be differentiated from nontreated control ulcers or normal stomach one month after injury. The Beer law and the heat-transfer factors relating to soft tissues are discussed. The coupled argon-ion laser-endoscope may be a safe tool to treat self-limited superficial bleeding gastric lesions. ( Arch Surg 111:750-755, 1976)

As recently as 1981, fewer than 12 medical centers in the United States were using lasers in the treatment of gastrointestinal (GI) disease. By 1984, 200 hospitals were using lasers for this purpose,1 and by the end of 1986,2 there were approximately 1,000. The reasons for such proliferation include increased applications of the use of lasers in GI problems, the relative ease with which they can be used, and the recent ruling by the Food and Drug Administration that the Nd:YAG laser is safe and effective and is therefore no longer considered to be an investigational device. Furthermore, lasers provide a multidisciplinary and multispecialty modality as well as therapeutic options where such choices did not exist or were limited previously.3 More importantly, they have been found to be safe, efficient, and cost-effective in most cases.

CO2, neodymium:yttrium -aluminum- garnet (Nd:YAG), and argonlaser welding of vascular. tissueRodney A. White, R. Patrick Abergel *, Richard Lyons *, Stanley R. Klein,George Kopchok, Richard M. Dwyer *, Jouni Uitto*Departments of Surgery and Medicine *, Harbor -UCLA Medical Center1000 W. Carson Street, Torrance, California 90509AbstractTne feasibility of welding thin- walled microvessels by laser has been established.This report summarizes our experience using laser welding to repair thick -walled, large-diameter, 4 to 8 mm canine veins and arteries using CO2, Nd:YAG and argon lasers. Weldingof venotomies is uniformly successful using CO2 and Nd:YAG lasers, and Nd:YAG venotomiesappear to heal more rapidly than sutured controls. Arterial welding has been accomplishedwitn the Nd:YAG and argon laser. Our preliminary experience shows promise for weldingboth large diameter veins and arteries using lasers. Laser welding may represent analternative for repair of small and large diameter vessels with several advantagescompared to conventional suture techniques.IntroductionVascular surgery has rapidly developed as a specialized field over the past 30 years.Many of the advances have relied on development of blood compatible synthetic polymers foruse as suture and prosthetic materials. Current areas of development in the repair ofvascular lesions require miniaturization of sutures, needles, prosthetic materials andinstruments to yield continued satisfactory results. Development of an expedientnonsuture technique for repairing arterial lesions and making anastomoses would be costand time effective, would reduce the technical difficulty of procedures and would improvethe quality of patient care.Several new techniques have been evaluated for repairing vessels. Automated suturingand stapling devices show some promise for increasing the speed and precision ofprocedures. Biologic adhesives, in particular fibrin glue, show encouraging results forrepair of arteriotomies and are useful adjuncts in forming anastomoses. Recentindications in the literature and preliminary experiments in our laboratory suggest thatlasers are applicable to vascular repair and may have several advantages over conventionaltechniques.This paper reviews our experience using CO2, Nd:YAG and argon lasers to repair otomiesin 4 to 8 mm canine arteries and veins. Previous studj,es "pave established the ability to

Clinical observations have suggested that low energy lasers might stimulate wound healing. To understand the mechanism of the biostimulation, we have previously examined the effects of low energy lasers on collagen production by human skin fibroblasts and reported an increase of collagen synthesis in vitro (J. Am. Acad. Derm. 11:1142-1150, 1980. To examine the effects of low energy lasers in vivo, hairless mice were experimentally wounded, sutured and subjected to laser irradiation by He-Ne laser with a power output of 1.56 mW, and an energy fluence of 1.22 J/cm2. Experimental wounds were subjected to laser treatment every other day, for a total duration of 2 months; control wounds remained untreated. Specimens from the wounds were then examined for histology, tensile strength and total collagen content. Results demonstrated a considerable improvement of the tensile strength of the laser-irradiated wounds at 1 and 2 weeks. Furthermore, the total collagen content was significantly increased at 2 months when compared to control wounds. These results suggest a beneficial effect of He-Ne laser on wound healing in vivo.© (1986) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This study compared the histology, biochemistry, and tensile strength of laser-welded and sutured canine venotomies, arteriotomies, and arteriovenous fistulas. Twelve animals had bilateral femoral vessels studied, with one repair (control) closed with interrupted 6-0 polypropylene sutures, and the contralateral repair (experimental) welded with the argon laser. Specimens were examined at weekly intervals from 1 to 4 weeks (four animals for each type of repair), and were evaluated histologically by hematoxylin and eosin, elastin, and trichrome stains; biochemically by the formation of [3H]hydroxyproline as an index of collagen synthesis; and mechanically by tensile strength determinations. At removal, all experimental closures were patent without hematomas, aneurysms, or luminal dilatation. Histologic and biochemical examination and tensile strength determinations suggest that laser welding may be an alternative to sutures for repair of large-diameter venotomies, arteriotomies, and arteriovenous fistulas, as healing is comparable to that seen with suture repairs up to 4 weeks postoperatively.

LASER energy has previously been shown to control bleeding from superficial gastric erosions in the dog. In the initial report by Goodale et al, 1 carbon dioxide laser energy was transmitted through a rigid, hollow endoscope. Subsequently, Nath et al 2 described a flexible fiberoptic delivery system through which argon laser energy could be transmitted. In 1975, Dwyer et al 3 reported the successful use of such a system to treat hemorrhage from superficial gastric erosions in dogs. This communication describes the use of argon ion laser phototherapy for the treatment of acute upper-gastrointestinal bleeding in man. Materials and Methods An argon ion retinal photocoagulator with a flexible fiberoptic delivery system was attached to the outside of an endoscope as previously reported. 3 The tip of the fiberoptic cable was covered by a protective cap, and the cap was equipped with two channels, one for water to wash the quartz

Endoscopic laser therapy for malignant esophageal obstruction is rapidly gaining widespread acceptance by the medical community. The standard approach utilizing the neodymium: yttrium, aluminum, garnet (Nd: YAG) laser was first described by Fleischer for squamous cell carcinoma of the esophagus and subsequently for adenocarcinoma of the gastroesophageal junction. According to his technique, treatment was begun at the proximal tumor margin and proceeded distally; as many as 13 treatments were necessary to complete therapy and relieve the obstruction. A new technique has been developed utilizing tumor dilatation so that treatment can be started at the distal tumor margin working retrogradely. This new technique has allowed treatment to be completed in a single session in most patients. This rapid completion of therapy has reduced the length of hospitalization and thereby hospital costs. It has also allowed patients to aliment earlier, thereby minimizing the metabolic consequences of prolonged intravenous feedings, has allowed patients to receive other forms of therapy on an outpatient basis, and has obviated the need for the chronic placement of tubes for drainage and feeding. The technique is described and discussed.

Applications of lasers in dermatologyGary Lask, R. Patrick Abergel, Richard M. Dwyer and Jouni UittoDepartment of Medicine, Division of DermatologyHarbor -UCLA Medical Center1000 West Carson Street, Torrance, California 90509AbstractLasers have gained considerable use in the field of dermatology for treatment of avariety of cutaneous lesions. In this overview, we are discussing the current applicationsof argon, CO2 and Nd:YAG lasers in dermatology. We are also exploring the future prospectsof laser research in the field of cutaneous biology.IntroductionAlthough lasers were introduced to medicine several years ago, only recently has amultidiciplinary usage been applied to the full spectrum of the clinical medicine.

In this study, we have developed a concept of wound closure by laser welding and studied the wound healing process. In the first set of experiments, six-millimeter long, full-thickness incisions were made in the skin on the back of hairless mice. Control wounds were closed with interrupted 5-0 prolene suture. The experimental wounds were approximated and closed by laser welding using a Nd:YAG (1.06 μm) laser. Selected wounds were excised for histopathology, transmission electron microscopy, tensile strength determination and assay of type I collagen specific messenger-RNA. The laser welded wounds demonstrated rapid healing with good cosmetic results. The tensile strength was identical both for laser welded and sutured wounds at 7, 16, and 21 days. A significant increase of type I collagen specific mRNA was noted in both specimens at 4, 10 and 16 days, but a higher level was recorded in the sutured specimens at day 16 (2652 vs. 911 U/pg total RNA). We further initiated a comparative study to identify the laser which would be most suitable for skin welding. For this purpose argon, Nd:YAG (1.06 μm and 1.32 μm) and CO 2 lasers were used to weld skin. Wound healing, tensile strength and collagen analyses were performed. The results indicated that both argon and Nd:YAG (1.32 μm) lasers achieved the most effective closure. These results suggest that laser welding provides an efficient method for closing skin wounds. The laser welding has clear advantages over conventional suturing techniques, being sterile, non-tactile, not requiring introduction of foreign materials into the wound, and providing improved cosmetic results.

Reprint requests: Garrett 1,~. M.D., Cardiovascular Medicine, Suite 202. LICD Professional Bldg.. 4301 S St., Sacramento, CA 95817. therapy” of heart and circulatory disorders is virtually unexplored. To determine the in vivo feasibility of transmitting laser energy intravascularly for the purposes of visualizing and treating peripheral artery pathoanatomy, a flexible fiberopticscope (Trimedyne, Inc., Arlington Heights, Ill.), equipped with a quartz fiber, was inserted via the left subclavian artery to the aortoiliac bifurcation in open-chest dogs (Fig. 1, A). For improved viewing, blood was diverted by normal saline infusion through the flushing channel of t,he fiberopticscope (Fig. 2, A). In addition, an area within the origin of the right iliac artery was then photoirradiated by a neodymium-YAG laser (five 2 to 3 second bursts of 60 W) (Fig. 2, B). Following these studies, the intervened vessels were removed, thereby verifying that the photoirradiation had indeed produced a lesion of coagulation necrosis (Fig. 1, A and B). Thus this investigation provides the initial demonstration of the practicality of conducting laser energy into living blood vessels and related structures as a new modality in the management of cardiovascular diseases.

• We compared the histologic features, tensile strength, and collagen synthesis of laser-welded and sutured arteriotomies. Four bilateral canine femoral or carotid arteries, 2 cm long, were studied at one through four weeks postoperatively, with one vessel (control) closed with interrupted 6-0 polypropylene sutures and the contralateral vessel (experimental) welded with an argon laser (0.5 W [1417 J/cm 2 ], four-minute exposure per 1-cm length of incision). Histologic examination revealed that laser-welded arteriotomies had less inflammatory reaction, more normal collagen and elastin reorientation, and similar endothelial continuity when compared with the control, sutured wounds. The tensile strength of the one- and two-week laser-welded specimens was less than that of sutured wounds and became approximately equal to sutured repairs at three and four weeks. There were no significant differences in the rate of collagen synthesis. There was no evidence of abnormal healing in the laser-welded specimens, suggesting that argon laser welding may be an alternative to suture repair of arteriotomies. ( Arch Surg 1986;121:1133-1135)

A flexible fiberoptic system has been used to deliver visible laser light into the upper gastrointestinal tract to arrest bleeding from various induced lesions. This procedure has achieved hemostasis at bleeding sites in the gastrointestinal tract of animals and suggests that bleeding lesions in the heman may be treated similarly without resort to surgical intervention or intensive medical management.