bluuebunny/crossref_metadata_2025 huggingface dataset:
Safety of high‐energy neodymium: YAG laser pulses in YAG sclerostomy
Authors: March Wayne F. , Gherezghiher Tseggai , Shaver Robert P. , Koss Michael C. , Nordquist Robert E.
Published: March 2007

YAG sclerostomy was performed in 15 eyes of nine cynomolgus monkeys. Individual pulse energies ranged between 10 and 135 millijoules. Total pulse energy ranged between 2,000 and 36,000 millijoules in order to test the extreme range of energy that might be required. Both acute effects and chronic effects were studied in the corneal endothelium, the lens capsule, the iris, the ciliary body, the retina, and the sclera. Techniques included flat preparations of the corneal endothelium, paraffin sections for light microscopy, and scanning and transmission electron microscopy. Our conclusion is that individual pulse energies of up to 135 millijoules with a total of up to 36 joules of energy are safe in monkey eyes when performing YAG sclerostomy.
Tissue precooling for thermochemical damage reduction during laser surgery
Authors: Laufer G. , Joachims H. Z. , Mordechovitz D. , Armon E.
Published: March 2007

This report describes a preliminary investigation of the possibility of reducing the thermal damage induced by lasers in the course of laser surgery. Skin incisions made by CO2 laser beams – with and without precooling – were evaluated and compared with scalpel cuts. Full thickness cuts were carried out on the flanks of adult cats. Precooling was achieved by spraying chlorethyl just before the laser application. Both the precooled and the regular laser incisions were bloodless. The precooled cuts however produced considerably less amount of charring and therefore smoother and cleaner cut edge.

The incisions were sutured and the cats were kept under supervision. Upon inspection four weeks later all incisions were completely healed. No skin thickening or keloid were present. The scar produced by the regular laser technique was much more pronounced and wide relative both to the scars of the precooled or the scalpel cuts which were almost alike.
Study of three laser systems for treatment of superficial varicosities of the lower extremity
Authors: Apfelberg David B. , Smith Teruko , Maser Morton R. , Lash Harvey , White David N.
Published: March 2007

Three separate laser modalities were investigated in the treatment of superficial varicosities/telangiectasias of the lower extremities. Sixteen patients were treated and followed for 12 months. The superpulse CO2, the pulsed focally specific CO2, and the Nd:YAG laser transmitted through a diffusing sapphire tip were able to produce cosmetically satisfactory permanent obliteration of vessels after a 12‐months follow‐up interval. These results were a significant improvement over six‐months results indicating a long fading time for laser treatment of leg veins.
Large vessel sealing with the argon laser
Authors: White Rodney A. , Kopchok George , Donayre Carlos , Lyons Richard , White Geoffrey , Klein Stanley R , Pizzurro Damon , Abergel R. Patrick , Dwyer Richard M. , Uitto Jouni
Published: March 2007

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.
Ultrastructural study of arterial wall repair after argon laser micro‐anastomosis
Authors: Godlewski G. , Rouy S. , Dauzat M.
Published: March 2007

A carotid end‐to‐end anastomosis was performed in 50 Wistar rats by means of a Coherent 900 argon laser. The vessel sealing was obtained with laser shots (average 19) or 300 mW power and 5‐second duration, the beam being focused in a spot of 150 μm diameter (1,700 W/cm2). From day 0 to day 120, 25 specimens underwent semithin and electron microscopic examinations. The results showed the immediate sealing effect of the argon laser owing to protein denaturation and collagen fusion of the media and adventitia 100 μm in width. Re‐endothelialization of the anastomotic line began by day 3, while myofibroblast proliferation was observed in the media by day 10. By day 20 media scar was still occupied by numerous myofibroblasts and surrounded by abundant collagen and elastic fibres. At long term the endothelial repair was complete and the anastomotic strength was assured by medial collagenous network.
Safe anesthesia for endoscopic laryngeal laser surgery
Authors: Anand Vijay K. , Herbert John , Robbett William F. , Zelman Warren H.
Published: March 2007

Anesthesia safety for endoscopic laryngeal laser surgery has been a major limiting factor for laser applications in the larynx and the hypopharynx. Several anesthesia techniques have been proposed and each technique appears to have its own limitations. This paper will deal with the distinct advantages offered by the malleable copper tube which is used for delivery of the open Venturi system anesthesia for endoscopic laser surgery. A retrospective study of 100 patients who have undergone this modality of anesthesia at our institution will be presented. Our conclusion from this study shows clearly the superiority of the copper tube over the conventional aluminium‐foil‐wrapped endotracheal tube in safety and the exposure of the larynx during surgery.
Laser smoke effect on the bronchial system
Authors: Freitag L. , Chapman G. A. , Sielczak M. , Ahmed A. , Russin D.
Published: March 2007

The photoresection of endobronchial tumors produces smoke which is partly inhaled by the patient as well as the surgical staff. In an animal study we investigated whether a single exposure or repetitive exposures to smoke might have harmful side effects on the airways. Eleven sheep were exposed to smoke produced by laser‐vaporizing (6,500 J) sections of bronchial tissue (1 cm3) in a Plexiglas chamber. The smoke analysis revealed 0.92 mg/liter particles with a mean particle size of 0.54 μm. Carbon monoxide content was estimated as 0.04%. We measured the effects of one or three separate ten‐minute exposures on airway resistance, gas exchange, and mucociliary clearance rate in the trachea. We found that the smoke inhalation resulted in a decrease of arterial PO2 with relatively little change in airway mechanics. Tracheal mucus velocity, a marker of lung mucociliary clearance, was significantly depressed in a dose‐dependent manner with increasing smoke exposures. Results of bronchoalveolar lavages performed before and one day after the exposure showed that the smoke inhalation induced a severe inflammation with dramatic increases of inflammatory cells. The total number of cells per milliliter increases from 3.2 million to 25 million; percent neutrophils increased from 2.3 to 45.6% and percent macrophages decreased from 86 to 41%. These findings indicate that the side effects of smoke inhalation during intrabronchial laser surgery should not be neglected. The impairment of the defense mechanism of the lung combined with the inflammation as well as hypoxia might be fatal in compromised patients. Effective smoke removal devices should be developed to protect the patients as well as the surgeon.
CO2 laser in decubitus ulcers: A comparative study
Authors: Juri Hugo , Palma José A.
Published: March 2007

This is a comparative study of conventional surgery (knife/electric knife) and CO2 laser surgery and their effect on the outcome of stage III (including muscle) and stage IV (including bone) decubitus ulcers with an average area of 400 cm2.

It is a prospective clinical study done with two groups of patients of similar age, economic and social background, as well with similar types of decubitus ulcers. Thirty patients were studied in each group.

The study demonstrated a statistically significant difference in favor of the patients treated with CO2 laser with regard to operative blood loss, 0.5 cc/cm2 or 20% (P < .01). infection rate (χ2 test, P < .01), and difference (60%) in recovery time (P < .01). This translated into an average saving of 23 hospitalization days per patient.

It also showed a difference, though not statistically significant, favoring the group treated with laser with respect to survival and full recovery. This probably is attributable to the lowered blood loss and infection rate as well as improved operative time and analgesia.
Molding of laser energy by shaped optic fiber tips
Authors: Ward Helen
Published: March 2007

The development of a new technique for laser recannalizing atheromatous vessels has inherent problems concerning heat damage to the vessel walls. A theoretical analysis of 2,100 light rays in large bulb end (output end) fibers compared to a standard flat end fiber showed (1) a much higher‐intensity focus; (2) a 125.4% increase in number of output rays (with respect to number of input rays) in the convergent output beam, due to multiple reflections/refractions (“stars” and “triangles”) and standing waves, in the large bulb end, compared to 48.6% in the flat end; (3) 83.69% energy in the converging beam of the large bulb end, compared to 48.6% in the flat end; (3) 83.69% energy in the converging beam of the large bulb end, compared to 46.1% energy in the flat end; and (4) a rapidly divergent beam after focus.

Hence, theoretically a wide area of plaque could be burnt off more rapidly with less heat conduction into the vessel walls.

Coupling efficiency was experimentally shown to be greatly increased by also having a bulb at the optic fiber input end.
Effects of simultaneous viewing and vaporization of plaques using the steerable, laser‐heated metal cap in the atherosclerotic monkey model
Authors: Theis Jerold H. , Lee Garrett , Chan Ming C. , Ikeda Richard M. , Lee Marshall H. , Rink John L. , Steffey Eugene P. , Thomas William P. , Mason Dean T.
Published: March 2007

A steerable, fiberoptic catheter coupled to a laser light guide tipped with a metal cap was used. Four monkeys fed an atherogenic diet for 7–8 years were angiographed and were found to have extensive mural plaque in the iliac arteries. Plaque sites in these monkeys were vaporized using the laser‐heated metal cap. Energies of 1.5–9 Joules were employed. Application of the energy was tangential or perpendicular to the plaque. Lased sites were examined histologically at 24 hr or at 3 months after treatment. No effect was seen at 1.5 Joules. Three to six Joules tangentially produced a superficial lesion that extended into the tunica intima. Six Joules perpendicularly produced a burn into the tunica adventitia, with damage to the vasavasorum. Nine Joules tangentially produced a burn into the tunica media. Three months after treatment, this lased site showed no stenosis or aneurysm formation.
Evaluation of sapphire tip Nd:YAG laser fibers in partial nephrectomy
Authors: Landau Stewart T. , Wood Thomas W. , Smith Joseph A.
Published: March 2007

Sapphire tips for Nd:YAG lasers fibers have been introduced recently. The increased energy density improves the cutting effect while, reportedly, preserving the hemostatic properties of Nd:YAG laser energy. The capacity of sapphire tip laser fibers to facilitate partial nephrectomy was tested in mongrel dogs. No advantage for this technique was demonstrated compared to standard methods of partial nephrectomy.
Differential effects of short‐ and long‐pulsewidth laser exposures on retinal ganglion cell response
Authors: Glickman Randolph D.
Published: March 2007

Time‐dependent effects of laser exposures on rhesus monkey retinal ganglion cells were studied with a Q‐switched, doubled Nd:glass laser, which produced 20 nsec pulses of 530‐nm light, and a continuous‐wave (CW) argon laser (514.5 nm), which produced exposures of 0.1‐msec to 0.1‐sec duration. Ganglion cell activity was recorded in situ by means of an intraocular electrode. Ganglion cells exposed to a single 20‐nsec exposure, at a sublesion intensity, produced a 60–90 sec discharge of action potentials and exhibited a 2 log or greater elevation of light threshold, depending on beam size and intensity. At equivalent energy levels, the longer exposures produced the same or slightly weaker effects. This result is not as straightforward as it seems. Submillisecond flashes bleach no more than 50% of the visual pigment because of photoregeneration. The Dowling‐Rushton relation predicts that a 50% bleach should produce only a 1.5 log loss of cone sensitivity. Exposures longer than 1 msec should not photoregenerate pigment (ie, more pigment will be bleached for a given exposure intensity). In view of the probable differences in pigment bleaching, it appears that the Q‐switched laser light adapts the cells out of proportion to the visual pigment actually bleached—a single‐cell analogue of Rushton's “theta” effect.
Effect of diodes‐laser silver arsenide‐aluminium (Ga‐Al‐As) 904 nm on healing of experimental wounds
Authors: Longo Leonardo , Evangelista Stefano , Tinacci Galliano , Sesti Anton Giulio
Published: March 2007

Diodes‐laser silver arsenide‐aluminum (Ga‐Al‐As) 904 nm, which was used because of its properties of good tissue penetration and manageability, applied 5 min daily for 5 days at 3,000 Hz of frequency (energy density = 3 J), promoted healing of experimental wounds in rats from both a microscopic and histologic point of view. The same laser applied in these experimental conditions (number of rats was eight for each group) at the same energy density (3 J) for 10 min daily during 5 days at 1,500 Hz of frequency did not affect the experimental wounds.
Endogenous porphyrin fluorescence in tumors
Authors: Harris David M. , Werkhaven Jay
Published: March 2007

The fluorescence of endogenous porphyrins in tumors has been attributed to the presence of several different species of bacteria inhabiting ulcerated and necrotic tissues. We have examined this “autofluorescence” in carcinogen‐induced tumors in the hamster oral mucosa and in patients with cancer of the oral cavity. In several instances, bright autofluorescence of normal tissues has been observed. This represents a potential false‐positive identification of cancer when systemic hematoporphyrin derivative fluorescence is used as a diagnostic technique.
Laser microsurgery in oncology: Indications, techniques, and results of 5‐year experience
Authors: Bandieramonte G. , Chiesa F. , Lupi M. , Marchesini R.
Published: March 2007

Multidisciplinary collaboration has enabled us to the CO2 laser in many different surgical fields. The 5‐year experience at the National Tumor Institute of Milan is reviewed for the evaluation of short‐ and medium‐term results of 321 laser surgical operations of the lower genital tract, 475 cases of lesions of the larynx and oral cavity, and 246 cases of skin lesions. A unified approach was used as regards safety measures, preoperative evaluation, and rules of application of laser instruments. The reliability of the surgical procedures, the proper selection of the cases, and the low rate of postoperative complications allowed outpatient treatment in 76% of the cases, thus reducing the hospitalization costs. The use of the microscope for laser resections under magnification was recognized to be preferable in routine surgical oncology practice. Short‐ and medium‐term clinical results with laser microsurgery were comparable to those with conventional surgery, especially when precise and conservative removal of periorificial lesions was required.
Laser therapy of tumor stenoses in the upper gastrointestinal tract: An international inquiry
Authors: Ell C. , Demling L.
Published: March 2007

The results of an international inquiry on palliative laser therapy of malignant inoperable stenoses in the upper gastrointestinal tract are reported. The results of the treatment of a total of 1,359 patients were collected. The data from laser users with experience in more than 50 treated patients (n = 1,184) were analyzed; 68.9% of the tumor stenoses were located in the esophagus, and 55.7% were not passable with the endoscope. The initial treatment was successful in 83.0% and the complication rate was 4.1% (49 of 1,184 patients). The mortality rate was 1.0% (12 of 1,184 patients).
Argon laser treatment of telangiectasia of the face and neck: 5 Years' experience
Authors: Achauer Bruce M. , Kam Victoria M. Vander
Published: March 2007

This study documents the treatment and long‐term follow‐up of telangiectasias of the face and neck with the argon laser. This study concurs with other examiners that treatment is effective with minimal complications and satisfactory long‐term results.
Laser balloon angioplasty: Effect of constant temperature versus constant power on tissue weld strength
Authors: Anand Raj K. , Sinclair I. Nigel , Jenkins Ronald D. , Hiehle John F. , James Leslie , Spears J. Richard
Published: March 2007

Thermal fusion of intimal plaque with the arterial wall during coronary balloon angioplasty may significantly reduce the incidence of abrupt closure and may reduce the occurrence of delayed restenosis by improvement of luminal size and shape. Although Nd:YAG laser energy has been shown to be effective in the thermal fusion of plaque‐arterial wall separations in vitro, the most efficient manner of energy delivery for rapid achievement of therapeutically useful equilibrium tissue temperature during laser exposure has not been defined. A comparison of weld strength achieved was therefore made between two formats of laser delivery: constant power vs. decremental power with an initial high dose followed by the minimal serial decrements necessary to maintain tissue temperature constant for 15 seconds. One hundred sixty‐six tissue discs of human postmortem aorta of 11 mm diameter were studied. Intimal plaque was separated from the media, the two layers were juxtaposed, a force of 4 pounds was applied, and a fiberoptic‐delivered laser beam was directed perpendicular to the tissue over a 3‐mm‐diameter nominal spot size. Weld strength was measured as the shear force required to separate completely the two tissue layers. The mean weld strength (75 g) achieved by use of the decremental power format was significantly higher (P < .01) than the mean strength (32 g and 56 g) achieved by using constant power for 20 and 30 seconds, respectively. The total laser energy used for the decremental power format was 235 joules, which was significantly less than the 320 and 480 joules used when constant power exposure for 20 and 30 seconds, respectively, was employed, despite the fact that the peak tissue temperature was similar for all three groups. It is concluded, therefore, that the use of decremental power to achieve quickly and, thereafter, to maintain a constant temperature provides better tissue weld strength at a lesser energy cost and hence is superior to the use of constant power.
Gas volume quantitation during argon ion laser ablation of atheromatous aorta in blood and 0.9% saline media with an optically shielded catheter
Authors: Davis G. Stefan , Bott‐Silverman Corinne , Goormastic Marlene , Gerrity Ross G. , Kittrell Carter , Feld Michael , Kramer John R.
Published: March 2007

Using an optically shielded fiber optic laser catheter, the amount of gas produced when firing an argon ion laser into 0.9% saline solution or blood alone and into atheromatous aorta in either a blood or 0.9% saline medium was quantitated. Energies from 0.25 to 4 joules (J) were used at powers of 2, 5, and 8 W. We found that total volume of gas produced is small not only at equilibrium (0.3 ± 0.1 μl/J when firing in blood alone and also when ablating aorta in blood or saline media) but also at peak (2.5 ± 0.2 μl/J firing in blood alone and 1.0 ± 0.1 μl/J or 0.9 ± 0.1 μl/J when ablating aorta in saline or blood, respectively). Because these volumes are small, a clinically significant event from a gas embolus is unlikely during intravascular laser ablation of atheromatous plaque in the energy and power range studied. No gas was quantitated when firing the argon ion laser into 0.9% saline solution alone. The peak gas volume when firing in blood alone was significantly greater than that produced in the other chamber environments. This is thought to be due to increased absorption of argon laser light by hemoglobin. The gas volumes produced by lasing aorta in 0.9% saline or blood were not statistically different.
Nd‐YAG laser energy distribution in an artificial obstruction: Influence of lasing parameters in a model of laser angioplasty
Authors: Rienks Rienk , Verdaasdonk Ruud M. , Borst Cornelius , Smits Peter C. , Jambroes George , van Gemert Martin J. C. , de Medina Etienne O. Robles , Hitchcock J. François
Published: March 2007

A Nd‐YAG laser (1064 nm) coupled to a silica fiber (0.6 mm core diameter) was used to create defects in a model of arterial vascular obstruction. We employed transparent agar doped with black ink as atheromatous material and studied the size and shape of defects created by various lasing parameter settings. By adding calcium sulphate to the agar its scattering properties were enhanced. The created defects correspond to a temperature boundary. The optical properties of the agar greatly influenced the size and shape of the created defects. In the agar with enhanced scattering properties, the created defects showed an infavourable penetration width‐depth ratio. Maximum width of penetration always exceeded the fiber diameter. This may contribute to an increased risk of vessel wall perforation in small vessels and, if the fiber is positioned close to the vessel wall, even when a coaxial position is maintained.

With increasing cumulative energy, both maximum depth and width of penetration leveled off in both agars. The results suggest that agar can be used to obtain empirically the lasing parameters that will minimize the risk of vessel wall perforation by an axially positioned fiber. The agar model needs further study to determine its limitations, but agar seems to be a useful substitute for atheroma in the study of laser catheter angioplasty.
Does low‐energy helium‐neon laser irradiation alter “in vitro” replication of human fibroblasts?
Authors: Hallman H. O. , Basford J. R. , O'Brien John F. , Cummins Laura A.
Published: March 2007

Cultured human fibroblasts were treated in a controlled, randomized manner to assess the effect of low‐energy (0.9 mW) helium‐neon (HeNe) laser irradiation on cellular proliferation. Two trials were performed: one with fibroblasts in the third to fourth passage and the other with fibroblasts in the 13th to 14th passage. In each trial, separate plasticpetri dishes were inoculated with the cells, maintained in a 5% CO2‐95% air atmosphere, and nourished with HB 102 media. Treatment began 48 h after inoculation with daily 60‐s irradiations of the “treated” cultures over a 5‐d period. Control cultures underwent the same handling but were not irradiated. A significant stimulative, or inhibitive, effect on replication was not found in either trial.
Prospective study of cutaneous phototoxicity after systemic hematoporphyrin derivative
Authors: Wooten Robert S. , Smith Kevin C. , Ahlquist David A. , Muller Sigfrid A. , Balm Rita K.
Published: March 2007

Hematoporphyrin derivative (HpD) is a photoactive, oncophilic substance that produces cutaneous photosensitivity as its only significant side effect. Twenty‐three patients who received systemic HpD and the usual light‐avoidance precautions were studied prospectively to determine the incidence and severity of cutaneous phototoxicity (CP). Seventeen of the 23 patients (74%) reported CP, including three patients (18%) who experienced blister formation. Symptoms of CP occurred for a mean duration of 6 weeks (range 5–23 weeks). Lack of compliance with restrictive photoprotective measures was felt to be a major contributing factor. Other HpD‐related complications included skin hyperpigmentation, ocular discomfort, pruritus, pain at injection site, and urticaria. CP and the restrictive measures to avoid it represent major disadvantages of the clinical use of HpD.
Laser angioplasty: An atherosclerotic swine model
Authors: White Christopher J. , Ramee Stephen R. , Card Hal G. , Abrahams Lisa A. , Svinarich J. Thomas , Wade Charles E. , Rodkey William G. , Virmani Renu
Published: March 2007

Rapid production of occlusive, atherosclerotic iliac artery lesions was achieved in 25 of 27 (93%) Yucatan miniature swine, using a combination of high cholesterol diet and mechanical endothelial denudation. Animals were fed a diet with 2% of their calories as raw cholesterol 2 weeks prior to balloon denudation of iliac arteries, which resulted in atherosclerotic lesions within 8 weeks. Early after denudation we have demonstrated total occlusion of arteries by fibrin thrombi, which in time organize and ultimately result in fibrotic occlusive disease. The arterial walls and intima show varying degrees of foam cell infiltration with destruction of the internal elastic lamina and calcification. Totally occluded lesions show fibrointimal proliferation, fibrosis, and multiluminal channels, which are probably secondary to organized thrombus. Our model of occlusive iliac artery disease involving vessels of 1 to 3 mm in diameter allows the development of catheter systems suitable for use in human peripheral and coronary arteries. This model is useful for the study of angioplasty, whether mechanical, balloon, or laser‐mediated.
The pulsed dye laser versus the Q‐switched Nd:YAG laser in laser‐induced shock‐wave lithotripsy
Authors: Thomas Stephen , Pensel Jürgen , Engelhardt Ralf , Meyer Wilhelm , Hofstetter Alfons G.
Published: March 2007

To date, there are two fairly well‐established alternatives for laser‐induced shock‐wave lithotripsy in clinical practice. The Q‐switched Nd:YAG laser is distinguished by the high‐stone selectivity of its coupler systems. The necessity of a coupler system and its fairly small conversion rate of light energy into mechanical energy present serious drawbacks. Furthermore, the minimal outer diameter of the transmission system is 1.8 mm.

The pulsed‐dye laser can be used with a highly flexible and uncomplicated 200‐μm fiber. However, the laser system itself is more complicated than the Q‐switched Nd:YAG laser and requires a great deal of maintenance. Biological evaluation of damage caused by direct irradiation shows that both laser systems produce minor damage of different degrees.

YAG laser lithotripsy with the optomechanical coupler was assessed in 31 patients with ureteral calculi. The instability and limited effectiveness of the fiber application system necessitated auxiliary lithotripsy methods in 14 cases. Dye‐laser lithotripsy is currently being tested in clinical application.

Further development, such as systems for blind application or electronic feedback mechanisms to limit adverse tissue effects, have yet to be optimized.

Nevertheless, laser‐induced shock‐wave lithotripsy has the potential to become a standard procedure in the endourologic management of stone disease.
Infrared laser bone ablation
Authors: Nuss Roger C. , Fabian Richard L. , Sarkar Rajabrata , Puliafito Carmen A.
Published: March 2007

The bone ablation characteristics of five infrared lasers, including three pulsed lasers (Nd:YAG, λ = 1,064 μm; Hol:YSGG, λ = 2.10 μm; and Erb:YAG, λ = 2.94 μm) and two continuous‐wave lasers (Nd:YAG, λ = 1.064 μm; and CO2, λ = 10.6 μm), were studied. All laser ablations were performed in vitro, using moist, freshly dissected calvarium of guinea pig skulls. Quantitative etch rates of the three pulsed lasers were calculated. Light microscopy of histologic sections of ablated bone revealed a zone of tissue damage of 10 to 15 μm adjacent to the lesion edge in the case of the pulsed Nd:YAG and the Erb:YAG lasers, from 20 to 90 μm zone of tissue damage for bone ablated by the Hol:YSGG laser, and 60 to 135 μm zone of tissue damage in the case of the two continuous‐wave lasers. Possible mechanisms of bone ablation and tissue damage are discussed.
Laser probe coagulation of bleeding canine ulcers
Authors: Van Stiegmann Greg , Sun John H. , Pearlman Nathan W. , Hammond William S.
Published: March 2007

A nonlight‐transmitting contact laser probe was used to treat acutely bleeding gastric ulcers in heparinized dogs. Thirty‐five treated ulcers responded with complete hemostasis following 21–92 seconds (mean, 32 seconds) application per ulcer. Ten control ulcers left untreated bled for 5–30 minutes (mean, 11 minutes). Hemostasis was maintained at treated sites for the entire observation period (60 minutes). Perforations did not occur, and there was no evidence of full thickness injury. Histological assessment confirmed a limited (0.2–0.5 mm) zone of coagulation injury. The laser probe is effective for control of acute bleeding in this canine ulcer model.
Combined effects of hematoporphyrin derivative phototherapy and adriamycin in a murine tumor model
Authors: Edell Eric S. , Cortese Denis A.
Published: March 2007

Hematoporphyrin derivative phototherapy (HpD‐PT) is currently being used experimentally in the treatment of various malignancies. The effectiveness of HpD‐PT appears to be limited to superficial malignancies because of its inability to penetrate more than 0.5–1 cm. The mechanism of action has been demonstrated to result from the formation of toxic singlet oxygen and other oxygen radicals. Preliminary work suggested that the addition of other chemical agents known to produce toxic oxygen radicals may enhance the effect of HpD‐PT. To test this hypothesis, we examined the effectiveness of HpD‐PT in the Walker 256 carcinosarcoma with and without Adriamycin. Tumor kill was estimated by calculating the area of necrosis on photomicrographic sections. From this area, a radius of tumor necrosis was determined and compared among various control and experimental groups. HpD‐PT was effective in this model when compared to control groups (radius of necrosis 3.79 ± 0.97 mm vs. 2.60 ± 1.26 mm, P < .05). The addition of Adriamycin significantly increased the radius of necrosis when compared to HpD‐PT (4.57 ± 1.70 mm vs. 3.69 ± 0.97 mm, P < .01). From this work we conclude that HpD‐PT demonstrates effective tumor killing in this murine model. The addition of Adriamycin significantly increased tumor kill.
Retinal thermal response to copper‐vapor laser exposure
Authors: Gabay Shimon , Kremer Israel , Ben‐Sira Isaac , Erez Gideon
Published: March 2007

A thermal model has been used for the interaction of an annular laser beam of a high‐repetition‐rate pulsed laser (copper‐vapor laser) with the retina of a rabbit. The model predicts the temperature rise at each retinal point, during and after the laser exposure, as a function of pulse energy, exposure time, and pulse repetition rate. The retinal effects for each set of treatment parameters were estimated according to the predicted temperature rise and were found to be identical with our previous experimental results. The character of the interaction between the copper‐vapor laser and the retina can be pretuned by the laser pulse repetition rate to fit the requirements of various treatments, permitting multiple uses of this laser for ophthalmic treatments.
Effective outpatient treatment of Kaposi's sarcoma of the urethral meatus using the neodymium:YAG laser
Authors: Wishnow Kenneth I. , Johnson Douglas E.
Published: March 2007

An unusual presentation of acquired immunodeficiency syndrome (AIDS)—a case of Kaposi's sarcoma involving the glans penis and fossa navicularis—was treated palliatively with neodymium:YAG (Nd:YAG) laser photoablation. A single outpatient treatment removed the two lesions and restored the patient's ability to void normally. The Nd:YAG laser proved extremely useful, providing effective outpatient therapy with minimal morbidity and excellent local results.
Percutaneous transluminal excimer laser angioplasty in total peripheral artery occlusion in man
Authors: Wollenek Gregor , Laufer Günther , Grabenwöger Florian
Published: March 2007

Laser angioplasty and laser‐assisted angioplasty have become a clinical reality. Producing sharply defined borders of the ablated area with minimal adjacent thermal damage, excimer lasers offer several proven and some potential advantages over conventional systems. To evaluate the feasibility of excimer laser angioplasty, we have treated one patient using 308‐nm radiation via a bare fiber in direct contact with the total occlusion of a right femoral artery. The lesion was successfully recanalized, thus allowing easy passage of the balloon catheter and subsequent dilatation. This percutaneous laser recanalization of an occluded peripheral artery is one of the first to be done in man using excimer laser radiation, thus demonstrating that the technique is feasible and the system is potentially useful.
Selective laser ablation of venous thrombus: Implications for a new approach in the treatment of pulmonary embolus
Authors: Lamuraglia Glenn M. , Anderson R. Rox , Parrish John A. , Zhang Danyi , Prince Martin R.
Published: March 2007

Laser radiation was employed to ablate venous thrombus or emboli with parameters that would not injure endovascular tissues. Output from a 482‐nm, 1‐μsec pulsed dye laser was delivered through a 320‐μmdiameter fiber to in vitro samples of fresh thrombus (T), venous or pulmonary emboli (VE), inferior vena cava (IVC), pulmonary artery (PA), pulmonary valve, and endocardium (atrial and ventricular). The mean threshold fluences for ablation of T and VE were 1.1 and 5.1 J/cm2, respectively. In contrast, the mean threshold fluences for IVC and PA were significantly higher (P < 0.0001), at 120 and 124 J/cm2, respectively. Ablation efficiency of thrombus was in excess of 100 mg/J, under conditions that caused no histologic injury to the pulmonary artery. To correlate ablation studies with optical absorption by the tissues, optical properties of fresh T, VE, IVC, and PA were studied. Hemoglobin species accounted for the more than 10 times higher 482‐nm absorption by T and VE compared to IVC and PA. This explains the differences in ablation thresholds and, thus, the selectivity encountered. These observations demonstrate, more than any other study in the vascular system, that with pulsed optical radiation, efficient laser ablation of venous thrombus is feasible with a wide margin of safety, and without damage to the surrounding vascular tissue.
Ablation of bone and methacrylate by a prototype mid‐infrared erbium:YAG laser
Authors: Nelson J. Stuart , Yow Lindy , Liaw L.‐H. , Macleay Lachlan , Zavar Rhonda B. , Orenstein Arie , Wright William H. , Andrews Jeffrey J. , Berns Michael W.
Published: March 2007

An erbium:YAG laser was used to generate 200‐μs pulses of mid‐infrared 2.94‐μm light in both the single and multimode configurations. Laser pulses were focused on the surfaces of both rabbit long bones and methacrylate blocks, and the tissue response was examined histologically. The depth of thermal injury was determined by ocular micrometry.

Over all energy levels tested, the erbium:YAG laser produced ablation of bone and methacrylate with minimal thermal damage to adjacent tissue. Increasing the laser energy per pulse produced increasingly wider and deeper grooves in both bone and methacrylate. However, such increase in laser energy produced a proportionately greater increase in the zone of thermal injury in methacrylate as compared with bone.

These studies suggest the feasibility of a surgical erbium:YAG laser in orthopaedics and other forms of ablative surgery.
Deep localized neodymium (Nd)‐YAG laser photocoagulation in liver using a new water cooled and echoguided handpiece
Authors: Godlewski G. , Rouy S. , Pignodel C. , Ould‐Said H. , Eledjam J. J. , Bourgeois J. M. , Sambuc P.
Published: March 2007

Thirty‐six deep hepatic lesions of localized photocoagulation were induced in 11 pigs by means of a neodymium‐YAG laser. Laser applications of 80 W/10 sec (10.190 W/cm2) were transmitted through a handpiece coupled to a water‐cooling circulation system to protect the quartz fiber and positioned through an echo‐guided trocar. During irradiation, temperature was sufficient for vaporization up to 5 mm from the laser source and high enough for tumor cell kill at a 10‐mm distance (54°C/60 sec). Intraoperative ultrasound visualized increasing photocoagulation (12–18 mm), and further controls demonstrated an echo‐free core of vaporization progressively covered by increasing fibrosis, well demarcated from normal parenchyma. Microscopy revealed central coagulative necrosis marginated from the third day by a growing fibrosis. By day 20 immunoblasts and mast cells were in profusion in the lesion border, and by day 120 a fibrotic network had invaded the scar and confirmed healing free of complication. This technique is proposed for deep vaporization of disseminated hepatic metastases.
Denudation of the entire mucosa of the canine urinary bladder using the neodymium: YAG laser with the MTR 1.5 contact probe
Authors: Wishnow Kenneth I. , Johnson Douglas E. , Grignon David , Ayala Alberto G. , Cromeens Douglas , von Eschenbach Andrew C.
Published: March 2007

Although the procedure of mucosal stripping or denudation of the urinary bladder was developed over 25 years ago to treat the potentially neoplastic mucosa in patients with low‐grade superficial transitional cell carcinoma of the bladder, the procedure was abandoned because of serious complications, including short‐term bladder hemorrhage and urinary extravasation and long‐term severe bladder contracture, ureteral reflux, and hydronephrosis. In this study, we used the neodymium:YAG laser with the MTR 1.5 contact probe to denude the entire mucosa of the canine urinary bladder. Evaluation of our results showed that mucosal denudation by this technique can be performed simply and safely without complications. Specifically, we encountered no significant bladder hemorrhage, urinary extravasation, bladder contracture, ureteral reflux, or hydronephrosis. We believe that the denudation procedure may be useful as a surgical means of treating the entire bladder mucosa in patients with proliferative epithelial lesions of the bladder including multifocal carcinoma in situ.
Subcapsular orchiectomy using the CO2 laser: A new technique
Authors: Wishnow Kenneth I. , Johnson Douglas E.
Published: March 2007

We report a technique for performing subcapsular orchiectomy using the CO2 laser. The procedure was simple and safe and was completed within 30–45 minutes in the 13 patients in whom it was carried out. Postoperative pain and swelling were minimal, and compression dressings were unnecessary. Postoperatively, the mean serum testosterone value was of castrate level. We conclude that CO2 subcapsular orchiectomy is a worthwhile addition to our surgical armory.
Endoscopic laser therapy for esophageal cancer: Present status with emphasis on past and future
Authors: Fleischer David
Published: March 2007

Although the major initial application for endoscopic laser therapy was for the management of gastrointestinal hemorrhage, it is now more common to use the laser endoscopically for the treatment of gastrointestinal neoplasms. A major body of literature surrounds the use of endoscopic laser therapy for esophageal cancer. The initial patient evaluation to determine if laser therapy is indicated includes a contrast radiograph, a screening endoscopy, and an imaging study. After these tests have been performed, it can be determined whether endoscopic laser therapy (ELT) is the best of the many endoscopic options. There is some difference of opinion as to the specifics of the treatment technique, and these are described. There is general agreement from reviewing the clinical data that it is possible to open the obstructed lumen in a large majority of cases and that functional success (the ability to achieve technically good results as well as clinical improvement without complications) is also possible in the majority of patients. Despite the information suggesting the benefits of ELT for esophageal cancer, there are both conceptual and technical limitations to the current approach to therapy. These limitations as well as potential future applications are discussed.
Effects of exposure time and pulse parameters on CO2 laser osteotomies
Authors: Clauser Carlo , Clayman Lewis
Published: March 2007

Two sets of experimental linear osteotomies were performed on frozen cortical bone by means of a high‐power industrial CO2 laser in the rapid superpulsed mode, varying the velocity of the operating table, the mean power of the laser beam, the pulsewidth, the pulse repetition rate, and the peak power. Both the depth and the width of the osteotomies were inversely related to the velocity and directly related to the mean power and to the pulsewidth, but they were not affected by changes in the repetition rate. The depth/width ratio, which describes the profile of the osteotomies, was affected by the mean power only. These data permit greater accuracy in the planning of laser osteotomies in cortical bone when using the rapid super‐pulsed mode.
Hazard zones and eye protection requirements for a frosted surgical probe used with an Nd:YAG laser
Authors: Rockwell R. James , Moss C. Eugene
Published: March 2007

Detailed radiometric analyses are reported on selected frosted‐style laser surgical probes that are in use in laser surgical procedures. These measurements were performed in order to determine their nominal hazard zone (NHZ) and the requirement for protective eyewear. All measurements were conducted under worst‐case conditions using a 30‐W Nd:YAG laser. The results show that for the style of probe tested, the NHZ can be considered a spherical volume of 1.3 m and will require eye protection devices having a maximum optical density rating of 4.3 at 1.06 μm for all personnel who may come within that range.
Pulsed Er:YAG‐ and 308 nm UV‐excimer laser: An in vitro and in vivo study of skin‐ablative effects
Authors: Kaufmann Roland , Hibst Raimund
Published: March 2007

Using a pulsed XeCl excimer laser (308 nm) and a pulsed Er:YAG laser (2,940 nm), we investigated skin ablation as a function of pulse number, radiant energy, and repetition rate. In vitro analysis of lesions performed in freshly excised human skin were consistent with in vivo results obtained from experiments on pig skin. Pulsed 308 nm laser radiation caused considerable nonspecific thermal tissue injury followed by an inflammatory reaction and impaired healing of lesions in vivo. These findings were especially pronounced with higher repetition rates, which would be required for efficient destruction of larger lesions. On the other hand, the 2.94 μm Er:YAG laser radiation produced clean and precise lesions with only minimal adjacent injury. In vivo skin ablation caused intraoperative bleeding with deeper penetration. The Er:YAG laser offers a promising surgical tool for careful removal of superficial epidermal lesions, if higher repetition rates, and an appropriate laser beam delivery system are available for clinical use.
Systemic effects of low‐power laser irradiation on the peripheral and central nervous system, cutaneous wounds, and burns
Authors: Rochkind Semion , Rousso Morris , Nissan Moshe , Villarreal Manuel , Barr‐Nea Liliane , Rees D. G.
Published: March 2007

In this paper, we direct attention to the systemic effect of lowpower helium‐neon (HeNe) laser irradiation on the recovery of the injured peripheral and central nervous system, as well as healing of cutaneous wounds and burns.

Laser irradiation on only the right side in bilaterally inflicted cutaneous wounds enhanced recovery in both sides compared to the nonirradiated control group (P < .01). Similar results were obtained in bilateral burns: irradiating one of the burned sites also caused accelerated healing in the nonirradiated site (P < .01). However, in the nonirradiated control group, all rats suffered advanced necrosis of the feet and bilateral gangrene.

Low‐power HeNe laser irradiation applied to a crushed injured sciatic nerve in the right leg in a bilaterally inflicted crush injury, significantly increased the compound action potential in the left nonirradiated leg as well. The statistical analysis shows a highly significant difference between the laser‐treated group and the control nonirradiated group (P < .001). Finally, the systemic effect was found in the spinal cord segments corresponding to the crushed sciatic nerves. The bilateral retrograde degeneration of the motor neurons of the spinal cord expected after the bilateral crush injury of the peripheral nerves was greatly reduced in the laser treated group.

The systemic effects reported here are relevant in terms of the clinical application of low‐power laser irradiation as well as for basic research into the possible mechanisms involved.
Thermal effects of stationary “hot tip” laser coronary probes: An in vitro assessment
Authors: Rosenthal Eric , Montarello Joseph K. , Palmer Tim , Curry Paul V. L.
Published: March 2007

Percutaneous laser thermal probe angioplasty requires sufficient laser probe flexibility to access the coronary tree. This may entail a loss of axial strength and the resultant slow advancement may lead to unwanted heating of the normal coronary artery proximal to the lesion. To assess the lateral thermal effects of stationary coronary laser probes, laser thermal energy (50–150 J) was delivered to 25 coronary artery segments (diameter 1.9–4.0 mm) in a perfused cadaver heart preparation using a 1.7 mm tip probe. Adherence to the vessel wall occurred in 19 segments, endothelial charring in 8 segments, and perforation in 3 segments. Endothelial charring was seen in 8 of 13 nonperfused segments but in 0 of 12 segments perfused at 60 ml/minute (P < 0.01). In all three perforations the vessel to probe diameter ratio was less than 1.6:1, perfusion was absent, and traction to dislodge the adherent probe was necessary. Lateral wall damage is a complication of stationary laser probes: smaller‐tipped probes which are advanced rapidly at the time of energy delivery may enhance the safety margins of coronary laser thermal probe angioplasty.
New method of photosensitizer accumulation for photodynamic therapy in an experimental liver tumor
Authors: Nishiwaki Yoshiro , Nakamura Satoshi , Sakaguchi Shukichi
Published: March 2007

A new sensitizing method of photodynamic therapy for malignant tumors and its effects was studied. Prepared for the study were pheophorbide a (Phd), dissolved in an oily contrast medium, Lipiodol (LPD‐Phd), and water‐soluble pheophorbide a (WS Phd) as sensitizers, and VX‐2 tumor in rabbit livers. The Phd distribution was compared after intraarterial (i.a.) administration of LPD‐Phd or W‐S Phd and intravenous (i.v.) administration of W‐S Phd. Phd was extracted with methanol at 24 h after injection, and the supernatant absorbance was measured at 670 nm by spectrophotometry. The tumor showed higher values of Phd than did the liver with LPD‐Phd i.a. and W‐S Phd i.a. (P < .01). Conversely, the tumor accumulated less Phd than did the liver with W‐S Phd i.v. (P < .05). We subsequently produced severe photodestruction in a Walker tumor in a Sprague‐Dawley rat liver with slight damage to adjacent liver tissue using LPD‐Phd i.a. and Nd‐YAG dye laser irradiation at 670 nm. The intraarterial administration of a photosensitizer may make it possible to treat liver tumors by photodynamic therapy.