bluuebunny/crossref_metadata_2025 huggingface dataset:
Partial nephrectomy using the Nd:YAG Laser: A comparison of the 1.06 μ and 1.32 μ lasers employing different delivery systems
Authors: Johnson Douglas E. , Wishnow Kenneth I. , von Eschenbach Andrew C. , Grignon David , Ayala Alberto G.
Published: March 2007

A comparative study of the 1.06 μ and the 1.32 μ Nd:YAG laser using a variety of delivery systems (focusing handpiece, freehand GI quartz fiber, or frosted laser scalpel) was undertaken to determine the usefulness of these modalities in performing partial nephrectomies in dogs. Variables evaluated included total operative time, total joules expended, estimated amount of blood loss, and extent of renal tissue damage. The contact laser scalpel provided the greatest precision and speed, but no hemostasis, and is therefore inappropriate for parenchymal renal surgery.

Evaluation of the other delivery systems showed no discernible differences in the extent of renal damage that could be attibuted to either wavelength or wattage used. The usual depth of acute renal damage ranged from 1.0 mm to 1.8 mm when the tissue was fixed immediately after completing the polar nephrectomy, but the damage had extended to 3.0 mm when tissue was examined after 6 weeks. No consistent differences in extent of cellular damage could be demonstrated between the renal cortex and medulla.

The lens system inherent in the focusing handpiece limited the total power (60 watts) that could be employed and surgery proceeded at a slower pace and required a greater expenditure of energy. Likewise, the maximal power that could be applied using the 1.32 μ laser was 25 watts and surgery also proceeded at a slower pace. Therefore, it was concluded that the optimal delivery system studied was the hand‐held GI quartz fiber, using the 1.06 μ, which provided maximum wattage, allowing surgery to proceed rapidly with minimal side effects (absence of “flashing,” heat build‐up) to the operative personnel and without increased tissue damage to the remaining renal parenchyma.
Protection of the rat lung from the harmful effects of laser smoke
Authors: Baggish Michael S. , Baltoyannis Pavlos , Sze Edward
Published: March 2007

Fourteen Sprague‐Dawley rats were exposed to CO2 laser exhaust that had first passed through smoke‐evacuator filters. Six rats breathed laser vapors that were filtered through commercially available, standard production model smoke‐evacuator systems. These animals demonstrated pulmonary lesions identical to but qualitatively less severe than those observed in animals breathing unfiltered vapor. Six additional rats were protected by the interposition of a cartridge filter plus an ultra‐low penetration air filter, which trapped 0.1 μm particles; the microscopic sections of the lungs of these experimental rats and two control rats were similar in appearance, i.e., no pathological changes were observed.
Pulsed CO2 laser tissue ablation: Measurement of the ablation rate
Authors: Walsh Joseph T. , Deutsch Thomas F.
Published: March 2007

Ablation of guinea pig skin using a CO2 laser emitting 2‐μsec‐long pulses has been quantified by measuring the mass of tissue removed as a function of incident fluence per pulse. The mass‐loss curves show three distinct regimes in which water evaporation, explosive tissue removal, and laser‐induced plasma formation dominate. The data are fit to two models that predict that the mass removed depends either linearly or logarithmically on fluence. Although the data are best fit by a linear dependence upon fluence, plasma formation at high fluences prohibited obtaining data over a wide enough fluence range to differentiate unambiguously between the two models. Ablation efficiency, ablation thresholds, and the optical penetration depth at 10.6 μm were obtained from the measurements.
Laser lithotripsy: Animal studies of safety and efficacy
Authors: Nishioka Norman S. , Kelsey Peter B. , Kibbi Abdul‐Ghani , Delmonico Francis , Parrish John A. , Anderson R. Rox
Published: March 2007

The safety and efficacy of pulsed tunable dye laser fragmentation of common bile duct stones was assessed in pigs. Laser pulses were conducted through a flexible quartz fiber that was in direct contact with stones that had been surgically implanted into the common bile duct. All calculi were rapidly fragmented into small pieces vithout significant damage to the common bile duct. The immediate and delayed effects of pulsed lasers on the common bile duct were also evaluated. The common bile duct demonstrated a high tolerance to laser‐induced damage even when the laser was discharged directly into the bile duct wall. These results suggest that laser lithotripsy can be performed in humans with a high degree of safety and efficacy.
Functional and histological restitution in the urinary tract after Nd:YAG laser coagulation
Authors: Pensel Jürgen , Sommer Konrad , Thomas Stephen , Lieck Petra , Baretton Gustavo
Published: March 2007

Current development in endourologic equipment has made possible the endoscopic application of the Nd:YAG laser in the treatment of urothelial tumors of the whole urinary tract. The clinical results are rather promising.

We controlled with various methods the healing processes of 14 rabbit ureters after Nd:YAG laser treatment as to morphological repair and physiological function. The ureters were irradiated transrenally with an energy of 60 J coagulating all wall layers. Healing of the laser lesions nearly to normal in all animals was observed 4 to 6 weeks after treatment.

The prevailing histological and physiological changes in the ureter are extremely slight and do not disturb the normal ureteral function. The results show the complete healing process of the ureter after laser coagulation and make the application of Nd:YAG laser in the upper urinary tract much more predictable.
Vasovasostomy in the murine vas deferens: Comparison of the Nd:YAG laser at 1.06 microns and 1.318 microns to the CO2 laser
Authors: Lowe Bruce A. , Poage Matthew D.
Published: March 2007

A comparison is made of laser anastomoses of the murine vas deferens at different energies with the neodymium (Nd):YAG laser at 1.06 μm and 1.318 μm and with the CO2 laser. A total of 28 welds were performed with a free‐hand technique employing a 600‐μm silicon fiber with the Nd:YAG and a hand piece with a 500‐μm spot size for the CO2. After 6 weeks, all animals were sacrificed and the vasa evaluated for patency. Fifteen out of 28 controls repaired with microsurgical techniques were found to be patent; 4/10 vasa were patent with use of the Nd:YAG at 1.318 μm at laser energies of 300 mW and 500 mW. At 1.06 μm, only 1/4 anastomoses was patent at a power setting of 1 W. None of the anastomoses performed with the CO2 laser was patent. Histologic study revealed intense fibrosis in all the lasered vasa, with sperm granuloma formation associated with most anastomoses. Although this is a preliminary study, it appears that the Nd:YAG laser at 1.318 μm and a power setting of 300–500 mW provides patency rates superior to the Nd:YAG at 1.06 μm and to the CO2 lasers and is equivalent to standard microsurgical techniques in the murine vas deferens.
Management of rhinophyma with carbon dioxide laser: Lahey clinic experience
Authors: Bohigian R. Kirk , Shapshay Stanley M. , Hybels Roger L.
Published: March 2007

The carbon dioxide (CO2) laser as a surgical tool for the difficult cosmetic problem of rhinophyma permits unprecedented refinement in treatment. Previously described conventional techniques have included the cold knife and the dermabrader. With these methods, hemostasis must be obtained with electrocautery, which if used extensively makes fine sculpting difficult. Seven patients with rhinophyma were treated with the CO2 laser at the Lahey Clinic from 1982 to 1987. We used a laser handpiece with a variable spot size. With this technique, we found the laser to be an excellent cutting tool while simultaneously providing superior hemostasis. In the followup period of up to 4.5 years, the cosmetic results have been excellent. Thus, the CO2 laser has become our treatment of choice for the management of patients with rhinophyma.
Changes in teeth and gingiva of dogs following laser surgery: A block surface light microscope study
Authors: Goultschin J. , Gazit D. , Bichacho N. , Bab I.
Published: March 2007

The effect of laser surgery on tissues of the periodontal apparatus was studied histologically in dogs using block surface light microscopy, a novel microscopical method. With this approach, changes in the hard and soft tissue components were concomitantly demonstrated; the method enabled preservation of the in situ relationship between these components. Following laser surgery, healing in the gingiva was delayed as suggested by the presence of epithelial ulcerations and dense inflammatory infiltrate. In the enamel and cementum the application of laser resulted in crater‐like defects that could be avoided only partially by insertion of a tinfoil shield into the gingival sulcus. In the vicinity of the cementoenamel junction these defects were filled with epithelium or periodontal ligament fibers; the close proximity of the hard and soft tissues at the defect sites suggested occurrence of new attachment. Enamel defects located coronal to the gingiva contained bacterial plaque. These histologic results do not demonstrate any substantial advantage of laser over conventional knife gingivectomy. Such advantage may be accomplished with the design of a special intraoral handpiece and further experiments.
Histopathology of human laser thermal angioplasty recanalization
Authors: White Rodney A. , White Geoffrey H. , Vlasak Jerry , Fujitani Roy , Kopchok George E.
Published: March 2007

Laserprobe thermal‐assisted balloon, angioplasty (LTBA) has demonstrated promising initial clinical results in recanalizing stenotic or occluded superficial femoral and popliteal arteries. Over the past year we have obtained six specimens of laserprobe thermal (LT) and LTBA treated total occlusions (avg. length 12 cm) for histopathologic examination from patients who were treated for limb salvage. Three tissue specimens were obtained acutely, and one was obtained at 6,8, and 13 days, respectively, after laser angioplasty at the time of revision for complications or failed procedures. Serial histologic sections of the treated LT segments demonstrated recanalization of atherosclerotic lesions to approximately 60–70% of the probe diameter. The LT channels were lined by a thin layer of carbonized or coagulated tissue and several layers of cell necrosis. The histology of the thermal injury was similar regardless of whether it was produced by the heated metal cap or by free argon laser energy. Stellate balloon angioplasty fractures were frequently filled with thrombus. Analysis of these human LT and LTBA specimens revealed that the thermal device produces a confined injury through the path of least resistance. Balloon dilatation produces fragmented cracks in the vessel wall, which appear to be more thrombogenic than the carbonized LT surface. With improved guidance methods, LTBA shows potential for continuing development.
Nd:YAG laser‐induced hyperthermia in a mouse tumor model
Authors: Waldow Stephen M. , Morrison Paul R. , Grossweiner Leonard I.
Published: March 2007

Hyperthermic tumor response induced by 1,064‐nm radiation from an Nd:YAG laser was investigated in DBA/2J female mice bearing the SMT‐F mammary carcinoma. The measured temperature‐depth profiles indicate that hyperthermic temperatures can be achieved in tumors ranging from 3 to 8 mm thick at power inputs on the order of 1 W. For small tumors, a 5‐week complete response rate exceeding 50% required 45 minutes at 45.0°C. Control of large tumors (6–8 mm thick) was not achieved. The observed tumor response rates are consistent with semiempirical time‐temperature relations based on other heating modalities.
Technique for measurement of one‐dimensional instantaneous ablation velocity
Authors: Rastegar S. , Van Gemert M. J. C. , Welch A. J.
Published: March 2007

An oscillating mirror scanned a He‐Ne laser beam along the length of a thin rod while the rod was ablated by an argon laser beam. The shadow of the scanning beam on an image plane provides a picture of the instantaneous ablation velocity of the rod. This configuration provides a unique method for investigating onedimensional ablation.
Mechanism of laser ablation in an absorbing fluid field
Authors: Isner Jeffrey M. , Dejesus Steven R. , Clarke Richard H. , Gal Dov , Rongione Anthony J. , Donaldson Roberta F.
Published: March 2007

Selection of a laser source for intravascular applications has frequently been predicated upon assumptions involving transmissability in blood of the wavelength of light emitted by a given laser. Standard absorption curves for ultraviolet radiation in blood and infrared radiation in water would suggest that transmission of ultraviolet radiation through a blood field and infrared radiation through any aqueous fluid field would be insufficient for tissue ablation. The present series of experiments was undertaken to determine whether these theoretical predictions would in fact obviate the use of these wavelengths in a blood field. Specimens of normal human myocardium and/or polyvinylchloride were submerged under blood and water and irradiated with ultraviolet radiation (351 nm) delivered as a focused beam and via an optical fiber and infrared radiation (10,600 nm) delivered as a focused beam. Ablation of myocardium was successfully accomplished with a focused beam of both ultraviolet and infrared radiation under as much as 5 mm of blood and with ultraviolet radiation via an optical fiber with the fiber tip up to 3 mm distant from the tissue specimen. High‐speed cine recordings of ablation carried out using a focused beam of laser radiation demonstrated that formation of a dynamic optical cavity is the basis for successful pulsed ultraviolet and infrared laser transanguineous tissue ablation. These results thus demonstrate that prediction of wavelength transmission through fluid media based on optical properties of a static fluid does not predict ability to accomplish ablation under dynamic circumstances of laser irradiation.
Comparison of wound healing between chopped mode‐superpulse mode CO2 laser and steel knife incision
Authors: Ben‐Baruch Gilad , Fidler James P. , Wessler Terry , Bendick Phillip , Schellhas Helmut F.
Published: March 2007

The healing of surgical incisions made with the steel knife and CO2 laser chopped wave mode (ChW) or rapid superpulse (RSP) mode were compared using histologic parameters and breaking strength of the scars on postoperative day 14. Using a miniature pig model the Sharplan 1100 laser incisions were made with an average power of 15 W and power density of 7.68 kW/cm2. Histological sections on postoperative day 14 revealed the knife scar measured .49 mm, was hypocellular, and contained visible bundles of collagen fibers. Both CO2 laser scars were less mature, the ChW scar measured 1.04 mm, the RSP scar measured 1.37 mm, and both contained cellular granulation tissue without visible collagen fibers. The breaking strength of the scars was measured with a tensiometer. Laser wounds were weaker than the knife wound. Scheffe test for variables was significant at P = .01 between the two laser modes and the knife. No significant difference was noted in the breaking strengths of incisions made with the chopped mode and superpulse mode.
Laser‐assisted vasovasostomy
Authors: Gilbert Peter T. O. , Beckert Rainer
Published: March 2007

To find a less time‐consuming alternative to conventional microsurgical vasovasostomy, we performed vasal anastomosis in four sterilized men by means of a Nd:YAG laser (wavelength 1,060 nm) under macroscopic conditions. After dissection of the vasal ends, the ends were approximated using 6‐0 prolene sutures as intervasal stents. The apposed tissue edges were welded by laser pulses of 0.5 sec in duration and 10 W in power. Postoperative sperm counts proved normal in two patients; one of them reported a successful pregnancy in his wife 12 months after vasovasostomy. One patient had cryptospermia and one patient oligoasthenospermia. Laser‐assisted vasovasostomy is a simple procedure and shortens the operative time. More patients still need to be studied to allow a favorable comparison with conventional suture techniques.
Effect of helium‐neon and infrared laser irradiation on wound healing in rabbits
Authors: Braverman Berton , McCarthy Robert J. , Ivankovich Anthony D. , Forde Danon E. , Overfield Michael , Bapna Mahapna S.
Published: March 2007

We examined the biostimulating effects of helium‐neon laser radiation (HeNe; 632.8 nm), pulsed infrared laser radiation (IR; 904 nm), and the two combined on skin wound healing in New Zealand white rabbits. Seventy‐two rabbits received either (1) no exposure, (2) 1.65 J/cm2 HeNe, (3) 8.25 J/cm2 pulsed IR, or (4) both HeNe and IR together to one of two dorsal full‐thickness skin wounds, daily, for 21 days. Wound areas were measured photographically at periodic intervals. Tissue samples were analyzed for tensile strength, and histology was done to measure epidermal thickness and cross‐sectional collagen area. Significant differences were found in the tensile strength of all laser‐treated groups (both the irradiated and nonirradiated lesion) compared to group 1. No differences were found in the rate of wound healing or collagen area. Epidermal growth was greater in the HeNe‐lased area compared to unexposed tissue, but the difference was not significant. Thus, laser irradiation at 632.8 nm and 904 nm alone or in combination increased tensile strength during wound healing and may have released tissue factors into the systemic circulation that increased tensile strength on the opposite side as well.
Effect of semiconductor GaAs laser irradiation on pain perception in mice
Authors: Žarković Neven , Manev Hari , Peričić Danka , Skala Karolj , Jurin Mislav , Peršin Anton , Kubović Milan
Published: March 2007

The influence of subacute exposure (11 exposures within 16 days) of mice to the low power (GaAs) semiconductive laser‐stimulated irradiation on pain perception was investigated. The pain perception was determined by the latency of foot‐licking or jumping from the surface of a 53°C hot plate.

Repeated hot‐plate testing resulted in shortening of latencies in both sham‐ and laser‐irradiated mice. Laser treatment (wavelength, 905 nm; frequency, 256 Hz; irradiation time, 50 sec; pulse duration, 100 nsec; distance, 3 cm; peak irradiance, 50 W/cm2 in irradiated area; and total exposure, 0.41 mJ/cm2) induced further shortening of latencies, suggesting its stimulatory influence on pain perception.

Administration of morphine (20 mg/kg) prolonged the latency of response to the hot plate in both sham‐ and laser‐irradiated mice. This prolongation tended to be lesser in laser‐irradiated animals.

Further investigations are required to elucidate the mechanism of the observed effect of laser.
Role of primary photoacceptors in low‐power laser effects: Action of He‐Ne laser radiation on bacteriophage T4‐Escherichia coli interaction
Authors: Tiphlova Olga , Karu Tiina
Published: March 2007

The effect of He‐Ne laser radiation (λ = 632.8 nm) on bacteriophage T4‐Escherichia coli WP2 interactions was studied. Irradiation of bacteria having respiratory chain components as primary photoacceptors accelerated their division in a dose‐dependent manner, but irradiation had no effect on the properties of the phage (measured as its ability to infect host cells). At the same time, exposure of bacteria to stimulating doses of He‐Ne laser radiation (from 103 to 6 × 104 J/m2) increased their ability to promote the growth of unexposed phages. These results clearly indicate that low‐power laser effects require primary photoacceptors (phage contains no chromophores for red light).
Laser vaporization of leiomyoma of the esophagus
Authors: Lange V. , Wenk H. , Schildberg F. W.
Published: March 2007

We present the case of a 67‐year‐old man with a stenosing leiomyoma of the esophagus, which led to dysphagia. Because of severe concomitant diseases, thoracotomy was not possible in this patient. Endoscopic laser ablation was a fast and successful treatment; more than 2 years have passed without any sign of recurrence.
Welding of gallbladder tissue with a pulsed 2.15 μm thulium‐holmium‐chromium:YAG laser
Authors: Popp Howard W. , Oz Mehmet C. , Bass Lawrence S. , Chuck Roy S. , Trokel Stephen L. , Treat Michael R.
Published: March 2007

Percutaneous endoscopic approaches to cholelithiasis would be facilitated by methods for welding gallbladder tissues. We evaluated the bursting pressure and histologic appearance of canine gallbladder tissue welded with a thulium‐holmium‐chromium:YAG (THC:YAG) laser producing a 2.15 μm pulsed output. The tissue absorption characteristics at this wavelength as well as the pulsed nature of the output permit tissue welding with limited collateral thermal damage. The THC:YAG is compatible with a flexible fiberoptic delivery system. Bursting strengths of the welded junctions averaged 42 mm Hg, which is above physiologically encountered pressures. Histologic sections of the bonded tissues revealed tissue fusion and limited thermal injury to the surrounding tissue. We feel that THC:YAG laser welding may be a useful technique in the clinical development of percutaneous endoscopic biliary surgery.
Microvascular anastomosis using a new diode laser system with a contact probe
Authors: Unno Naoki , Sakaguchi Shukichi , Koyano Kenichi
Published: March 2007

The aim of the present study was to demonstrate the usefulness of our newly produced diode laser device (an 830‐nm output of 190 mW CW) for microvascular end‐to‐end anastomoses. In the device, diode laser energy is delivered to a contact ceramic tip with a 200‐μm diameter output end. Its wavelength is 830 nm and its power 60 mW. This device is small (30 × 25 × 10 cm), light weight (gross weight 3kg), and easy to manipulate. Compared with conventional microvascular suture anastomosis (CMSA), the time required for the laser‐assisted vascular anastomoses (LAVA) was reduced by almost half. Anastomosed portions of both methods were examined 1, 2, 4, 12, and 24 weeks later for patency and aneurysm formation. The patency rate and incidence of aneurysmal formation were the same in both groups. Histological examination revealed that LAVA is superior to CMSA in the smoothness of the inner surface, less inflammatory reaction, and normal collagen and elastic reorientation. The tensile strength and bursting pressure measured immediately after anastomosis demonstrated no significant difference between the two groups. It was concluded that this diode laser contact method may be clinically useful for microvascular surgery.
Laser balloon angioplasty versus balloon angioplasty in normal rabbit iliac arteries
Authors: Jenkins Ronald D. , Sinclair I. Nigel , Leonard Bradley M. , Sandor Tamas , Schoen Frederick J. , Spears J. Richard
Published: March 2007

Reduction of vascular recoil is an important goal of laser balloon angioplasty (LBA), wherein Nd:YAG laser radiation is delivered radially during balloon inflation. To define the acute and chronic effects of LBA on the normal arterial lumen in comparison with those of balloon angioplasty (BA), 36 New Zealand White male rabbits (3–4 kg) were subjected to LBA of an external iliac artery and to BA of the contralateral artery with two 1‐minute balloon inflations. During LBA, which was performed during the second balloon inflation, either 300 (n = 26) or 176 (n = 10) J were delivered to achieve high and moderate laser doses, respectively, in different LBA groups. Angiography was performed pre‐ and post‐LBA/BA and subsequently at intervals of either 1, 2, 7, 28, 48, or 223 days. Automated analysis of digitized images was used to measure lumen diameter. No instance of perforation or thrombosis occurred. LBA‐treated arteries acutely showed an increase in mean diameter over baseline (+.5 mm, P<.01) and that of BA‐treated arteries (+.4 mm, P<.01). While arteries treated with the high laser dose showed a loss of the initial gain in lumen diameter by 1 month, caused by both extravascular fibrosis of the thin‐walled (<0.1 mm) artery and mild neointimal proliferation which were not reduced by daily administration of aspirin in seven rabbits, arteries treated with the moderate laser dose retained the increment in mean diameter at 1 month over that of BA‐treated arteries (+.5 mm, P<.05). Thus, unlike BA, LBA increases luminal diameter acutely and, at a moderate laser dose, chronically.
Experimental studies of the application of the Er:YAG laser on dental hard substances: I. Measurement of the ablation rate
Authors: Hibst Raimund , Keller Ulrich
Published: March 2007

Up to now lasers have not achieved any practical importance in dentistry for drilling teeth because of considerable damage to the surrounding tissue. We studied the application of pulsed 2.94 μm Er:YAG laser radiation in vitro on extracted teeth to remove enamel, dentin, and carious lesions. The depth and diameter of laser‐drilled holes were measured as a function of pulse number and radiant exposure. The tissue removal is very effective both for dentin and enamel.
Failure of carbon dioxide laser excision of keloids
Authors: Apfelberg David B. , Maser Morton R. , White David N. , Lash Harvey
Published: March 2007

Seven patients with nine keloids have been treated by excision with the carbon dioxide laser. Eight of the nine keloids have recurred to their original or close to original size as early as 10 months following treatment and as late as 22 months. Keloids included in this study were located on the trunk, nuchal region, back, and earlobe. Only one patient (who underwent earlobe keloid excision) has greatly improved keloids after only 9 months follow‐up, but this patient needs to wear pressure earrings continuously. The long‐term benefits of keloid excision with the carbon dioxide laser is not demonstrated in this case study series.
Time constants in thermal laser medicine
Authors: van Gemert Martin J. C. , Welch A. J.
Published: March 2007

Temperature rise of laser‐irradiated tissue due to direct absorption of laser light is related to laser parameters (power, spot size, irradiation time, and repetition rate) and tissue parameters (absorption and scattering coefficients, density, heat capacity, and thermal conductivity). Solutions to the bio‐heat equation are approximated by introducing axial (z) and radial (r) time constants for heat conduction that represent two parallel channels for heat conduction. These axial (τz) and radial (τr) time constants are found proportional to squared distances (zO2, rO2) that represent the extent of axial and radial temperatures respectively. For convenience, zO and rO are approximated to the axial and radial extent of laser light in the tissue. The resulting solution of the bioheat equation, expressed as temperature rise as function of time and position, is obviously exact for irradiation times short compared to τz, τr (adiabatic heating), but is also a quite reasonable approximation up to irradiation times three times the overall time constant. Comparison with (exact) numerical computations show that this holds for all ratios of (light) penetration depth to laser‐beam radius; for strongly scattering materials, smaller laser beams give better predictions than do larger laser beams. Several examples of clinical relevance are discussed, such as multiple‐laser‐pulse irradiation of high‐ and low‐absorbing tissues and laser treatment of port‐wine stains, with some unexpected results that also show potential clinical relevance.
Catheter‐directed neodymium:YAG laser injury of the left ventricle for arrhythmia ablation: Dosimetry and hemodynamic, hematologic, and electrophysiologic effects
Authors: Vincent G. Michael , Fox Jolene , Knowlton Kirk , Dixon John A.
Published: March 2007

The study evaluated catheter‐directed laser injury of the left ventricular myocardium in a canine model as a potential method for treatment of resistant ventricular tachycardia. The relationship between laser energy delivered, the laser delivery characteristics, and the lesion size was evaluated both in vitro and in vivo. The effect of laser injury on several hematologic and hemodynamic parameters was studied. Programmed electrical stimulation studies were performed to assess the proarrhythmia potential of laser injury of the myocardium.

The results showed the depth and diameter of myocardial injury to be directly related to total laser energy applied. Both depth and diameter of injury were increased by multiple applications of laser energy to the same myocardial location. One‐half to full thickness left ventricular injury was produced without perforation or embolization. Endocardial vaporization occurred only with laser powers higher than necessary to produce full‐thickness injury. There was no sustained effect on the hemodynamic or hematologic variables studied, nor were proarrhythmia effects identified. The laser injury produced in these studies was of smaller magnitude than might be necessary for clinical arrhythmia ablation, and the lack of sustained hemodynamic effects and pro‐arrhythmia potential needs to be verified in subsequent studies with larger laser lesions. The results support continued evaluation of catheter‐directed laser injury of the myocardium as a potential method for elimination of life‐threatening ventricular arrhythmias.
Pulsed holmium laser ablation of cardiac valves
Authors: Lilge Lothar , Radtke Wolfgang , Nishioka Norman S.
Published: March 2007

Ablation efficiency and residual thermal damage produced by pulsed holmium laser radiation were investigated in vitro for bovine mitral valves and human calcified and noncalcified cardiac valves. Low‐OH quartz fibers (200 and 600 μm core diameter) were used in direct contact perpendicular to the specimen under saline or blood. Etch rate was measured with a linear motion transducer. Radiant exposure was varied from 0 to 3 kJ/cm2. For 200‐μm fibers, the energy of ablation was approximately 5 kJ/cm3 in noncalcified and 15 kJ/cm3 in calcified valves. Etch rates were dependent on mechanical tissue properties. Maximum etch rate at 1,000 J/cm2 was 1–2 mm/pulse at 3 Hz repetition rate. Microscopic examination revealed a zone of thermal damage extending 300 μm lateral into adjacent tissue. Thermal damage was independent of radiant exposure beyond twice threshold.
Argon laser vascular fusion: Venous and arterial bursting pressures
Authors: Vlasak Jerry W. , Kopchok George E. , Fujitani Roy M. , White Rodney A.
Published: March 2007

This study was designed to determine the optimal laser power (watts) for maximal strength of argon laser vascular fusions by measuring bursting pressures of repairs. Longitudinal incisions (n = 105) measuring either 2.5 or 5 mm in length were performed in canine femoral, carotid, and jugular veins and arteries and were fused with the argon laser at 0.3, 0.5, 0.7, or 0.9 W power. Total exposure time for each repair (50 to 80 sec/0.5 cm) was adjusted to yield identical energy fluences of 1,100 J/cm2. Bursting pressure of the fusions was determined by monitored infusion of anticoagulated blood into an isolated segment of the vessel that contained the fusion. Mean bursting pressures for venous and arterial repairs were significantly higher in the 2.5 mm incisions compared with the 5 mm incisions (P < 0.05). Venous and arterial repairs of equal length performed at each power resulted in equivalent bursting strengths, except that 5 mm venous segments fused with 0.9 W withstood lower pressures than all other venous repairs (P < 0.05), and 5 mm arterial segments were in turn significantly weaker at 0.3 W (P < 0.02). We conclude that argon laser fusion is equally suitable for repair of medium‐sized veins and arteries and that immediate strength decreases with increasing length of repair. To maximize strength of longer repairs, venotomies should be welded at power settings between 0.3 and 0.7 W while arteriotomies should be fused at power settings between 0.5 and 0.9 W. The differences in optimal power may be explained by variable wall composition and thickness between veins and arteries.
In utero fetal surgery using a milliwatt carbon dioxide laser
Authors: Hallock Geoffrey G. , Rice David C.
Published: March 2007

In utero surgery represents a future new frontier with unknown possibilities for medical intervention. Since the presently available microsurgery instruments are too cumbersome or indelicate, low‐energy carbon dioxide lasers have been investigated as a tool that holds promise as a fetal scalpel and hemastatic device. Preliminary results demonstrate that continued investigation is necessary to limit the zone of tissue destruction in these most diminutive patients.
Effect of excimer laser radiant exposure on uniformity of ablated corneal surface
Authors: Fantes Francisco E. , Waring George O.
Published: March 2007

The argon fluoride (193 nm) excimer laser is being used to change the anterior corneal curvature for correction of refractive errors. Uniformity of the surface following laser ablation may play an important role in the rate of epithelial healing and amount and type of stromal scarring. To test the effect of radiant exposure (fluence) on surface smoothness, we ablated rabbit corneas with the 193 nm argon fluoride excimer laser at nine radiant exposures from 50 to 850 mJ/cm2. A total energy of 100 J/cm2 was used for each ablation at a frequency of 1 Hz. Scanning electron microscopy demonstrated progressive improvement of surface smoothness with increasing radiant exposures. Transmission electron microscopy demonstrated no consistent increase in thickness to the surface condensate (pseudomembrane) with increasing radiant exposure. Improvement in surface quality associated with increasing radiant exposures may result from a more uniform depth of ablation per pulse in the corneal lamellae that absorb laser wavelengths differently. Radiant exposures at levels where the depth of ablation is the same regardless of increasing energy densities achieve a more uniform surface because inhomogeneities in the beam and variation in energy from pulse to pulse do not affect the ablation rate.
Lactate dehydrogenase in laser incisions: A comparative analysis of skin wounds made with steel scalpel, electrocautery, superpulse—continuous wave mode carbon‐dioxide lasers, and contact Nd:YAG laser
Authors: Hukki Jyri , Lipasti Jarmo , Castren Maaret , Puolakkainen Pauli , Schröder Tom
Published: March 2007

A histochemical method for demonstrating lactate dehydrogenase activity was used in addition to standard Van Gieson stain to study early alterations near wounds made in pig skin by steel scalpel, electrocautery, two modes of CO2 laser (the rapid superpulse mode and the continuous wave mode), and contact Nd:YAG laser. The enzyme‐free zone near the wounds made using the thermal knives appeared to be twice as wide as the necrotic zone observed with Van Gieson stain. In polarized light, the enzyme‐free area showed two zones of equal width with respect to birefringence of collagen fibers. The zone lacking birefringence correlated well with that observed with Van Gieson stain. The birefringent zone represented functionally damaged tissue with more or less normal structures by light microscopy. The damage to adjacent tissue caused with the thermal knives seems to be considerably larger than has usually been reported.
Comparative study of suture and laser‐assisted anastomoses in rat sciatic nerves
Authors: Benke Timothy A. , Clark John W. , Wisoff Peter J. , Schneider Steven , Balasubramaniam Chidambaram , Hawkins Hal K. , Laurent John , Perling Lance , Shehab Anne
Published: March 2007

Conventional suture repair of peripheral nerves results in a fibrotic reaction that is detrimental to nerve regeneration. As an alternative procedure known as “laser‐assisted” repair, a laser can be used, along with a reduced number of sutures, to reanastomose severed peripheral nerves. To explore the long‐term implications of this technique, the right sciatic nerves of Sprague‐Dawley rats were surgically cut and reanastomosed either by means of four epineurial sutures or two epineurial sutures and CO2 laser welds. Tensile strength, electrophysiology, histology, and functional studies were performed up to 11 months postoperatively. Tensile strength measurements indicate no long‐term disadvantage with the laser‐assisted technique, although the short‐term tensile strength is lower than with conventional suture repair. The conduction velocities of the repaired nerves were similar for both techniques; however, laser‐assisted repaired nerves were found to have lower stimulation thresholds and reduced branching compared to the suture repaired nerves. The measured functional recovery was similar for both repair techniques.
Ablation of recurrent and metastatic lntraabdominal tumor with the CO2 laser
Authors: Chevinsky Aaron H. , Minton John Peter
Published: March 2007

A retrospective study was carried out to determine the usefulness of the CO2, laser in the management of patients with recurrent and metastatic intraabdominal tumors. Twenty‐six intraabdominal procedures utilizing the laser were carried out on 24 patients at The Ohio State University between 1984 and 1988. This included 11 patients with recurrent adenocarcinoma of colonic origin, 3 patients with malignant carcinoid tumors, 3 patients with ovarian carcinomas, and one patient each with metastatic pheochromocytoma, appendix, breast, stomach, and lung carcinoma. In addition, there was one patient with pseudomyxoma peritoneii and one patient with both colonic and ovarian carcinoma. Tumors were located in the retroperitoneum (3), pelvis (2), liver (11), bowel serosa (5), diaphragm (4), mesentery (31), and peritoneal implants (3). The laser was used as an adjunct to standard surgical techniques and in most instances was combined with other operative procedures. Its use was greatest in cases where en bloc resection was impossible, as with hepatic lesions located near the hepatic veins or vena cava. Additional benefit was derived in cases where cytoreductive or debulking surgery was useful as in ovarian carcinoma and metastatic neuroendocrine tumors. All four patients with neuroendocrine tumors are still alive 3, 7, 12, and 56 months after surgery. In addition, symptom relief was apparent in all after surgery. All patients with ovarian carcinoma are also alive 9–29 months after surgery. Six of the 11 patients with recurrent colon carcinoma are alive 3–21 months after surgery, and those who died survived an average of 10 months after surgery. Most showed a lowering of the serum CEA level after surgery. The patients with appendiceal primary and the one with pseudomyxoma peritoneii are both alive 12 and 15 months after surgery. The carbon dioxide laser is a valuable tool for the ablation of metastatic and recurrent intraabdominal tumors and may be used in conjunction with standard techniques in the overall management of these patients.
Light attenuation of human liver and hepatic tumors after surgical resection
Authors: Nakamura Satoshi , Nishiwaki Yoshiro , Suzuki Shouhachi , Sakaguchi Shukichi , Yamashita Yutaka , Ohta Kazuyoshi
Published: March 2007

The attenuation of light in the human liver and hepatic tumors was measured in the 410‐, 630‐, and 670‐nm wavelengths. Optical fibers coupled to a photon‐counting system were positioned within the tissues to determine the light flux and were attached to a caliper gauge to measure the fiber separation distance. Five resected specimens each of metastatic carcinoma from the colon with normal liver and hepatocellular carcinoma with cirrhosis of the liver were used immediately after surgical resection. Metastatic tumors showed the deepest penetration at all wavelengths. A significant difference appeared between the cancerous and noncancerous tissues (P < .01). Additionally, the cirrhotic liver tissues showed significant deep penetration by all wavelengths examined in comparison with normal liver tissues (P < .01). The implications of light dosimetry for clinical application from the results of our study are discussed.
Methods for the endoscopic photographic and visual detection of helium cadmium laser‐Induced fluorescence of photofrin II
Authors: Rogers David W. , Lanzafame Raymond J. , Blackman Jeffrey , Naim John O. , Herrera H. Raul , Hinshaw J. Raymond
Published: March 2007

Endoscopic detection of small tumors is key to the early diagnosis and treatment of malignancy. This paper describes a simple, endoscopic detection system which enables tumor localization and a permanent record based on the laser–induced fluorescence of dihematoporphyrin ether (LIFD). Spectral analysis of dihe‐matoporphyrin ether (DHE, Photofrin II) was performed with a Perkin Elmer LS‐5 scanning fluorimeter. DHE at concentrations of 50 μg/ml and 5 μg/ml in 95% ethanol were tested, demonstrating fluorescence quenching at 50 μg/ml DHE at 406 nm excitation. This phenomenon was not observed at 442 nm excitation. Based on this data and the availability of the helium cadmium laser, a series of endoscopic detection systems was developed and tested utilizing a LiConix 4240NB helium cadmium laser (TEMoo, 442 nm, 40 mW). A fiber with a microdiverging (MDL) lens was used. Irradiance achieved at the tip of the fiber was 31.58 mW/cm2 for MDL. A Corning 34832 (550 nm) sharp cutoff barrier filter was coupled to an Olympus OES BF2T10 bronchoscope. Successful detection of LIFD was obtained.

Direct observation of LIFD is possible when wearing Laserguard argon safety goggles (OD 15 at 488 nm, OD 11 at 514 nm). Photographic recording of LIFD was performed with the following cameras and parameters: Olympus OM‐2S camera (OM2) with EES135 film (ISO 1600) with a 4‐second exposure (method 1) and the Olympus OES SCP‐10 instant camera with Polaroid 779 (ISO 640) film and a 120‐second exposure (method 2). The photographic methods demonstrate the red fluorescence of DHE on filter paper disks at concentrations of 0.5 μg/ml (500 ng/ml). The visual method allows detection of as little as 0.25 μg/ml (250 ng/ml) DHE. These methods provide a low‐cost method for tumor detection within the range of DHE concentrations employed clinically. The use of the helium cadmium laser for laser‐induced fluorescent endoscopic detection of Photofrin II is reported.
Laser thermal angioplasty probe (“hot tip”) temperature: Effects of flow
Authors: Rosenthal Eric , Foussas Stephanos , Montarello Joseph K. , Boyd Edward G. C. A. , Curry Paul V. L.
Published: March 2007

The temperature developed by the laser thermal (“hot tip”) probe during arterial recanalisation is primarily dependent on the rate of energy delivery and the rate of dissipation to the surrounding medium. While higher probe tip temperatures enhance the efficacy of atheroma ablation, so too is the incidence of adverse effects increased. We studied the temperature developed in the probe tip in an artificial circulation using both saline and blood. In saline the peak probe temperatures were limited to 100°C (boiling point), falling with each increment in flow. Small discrepancies in probe tip temperature were found between probes and within probes at different times and may be due to malalignment of the optical fibre‐metal cap coupling, temperature measurement inaccuracy, tip insulation, or generator output instability. In blood, charring and clot formation insulated the tip raising the temperature (up to 700°C within 5 seconds at 10 W) but also retarded dissipation of heat to the surroundings. The degree of clot and char formation was critical in determining subsequent thermal responses in any particular probe. The unknown rate and quantity of char buildup and changing blood flow during in vivo angioplasty are likely to be important obstacles to developing a reliable thermal feedback control system.
Long‐Term survival of a lung cancer patient treated with photodynamic therapy
Authors: Nelson J. Stuart , Fairshter Ronald D. , Berns Michael W.
Published: March 2007

A 63–year‐old male, status post‐right pneumonec‐tomy, presented with hemoptysis. Although chest X‐ray and CAT scan film findings were negative, bronchoscopy with biopsy from the left mainstem bronchus demonstrated squamous cell carcinoma. Because of the inoperable location of the lesion, the patient was treated with photodynamic therapy (PDT) in February 1984. At present, the patient is cancer free more then 6 years after PDT.
Combination treatment for massive cavernous hemangioma of the face: YAG laser photocoagulation plus direct steroid injection followed by YAG laser resection with sapphire scalpel tips, aided by superselective embolization
Authors: Apfelberg David B. , Maser Morton R. , White David N. , Dds Harvey Lash , Lane Barton , Marks Michael P.
Published: March 2007

A massive cavernous hemangioma of the face in an 11 month old child has been successfully resected utilizing a combination of laser and non‐laser techniques. The hemangioma was initially treated twice with YAG laser photocoagulation plus direct injection of steroids. This treatment promptly stopped the rapid growth and induced blanching as well as a 25% shrinkage with each treatment. Arteriogram with superselective embolization produced a further shrinkage of the hemangioma. Finally, the contact YAG laser with sapphire scalpel tips was utilized for complete and cosmetically satisfactory hemangioma resection. The treatment of a massive cavernous hemangioma by a combination of modalities is discussed.
Preliminary experiments of possible uses in medicine of novel plastic hollow fibers for transmission of CO2 radiation
Authors: Kaplan Isaac , Giler Shamai , Dror Jacob , Gannot Israel , Croitoru Nathan
Published: March 2007

Plastic hollow fibers for the transmission of CO2 laser energy in curved paths were produced by plating the inner surface of plastic tubes with a metal film and dielectric film upon that. These fibers can transmit high power, up to 40 W at the outlet, with high transmission yield even through several bendings. To demonstrate a possible use of the fibers, they were checked for their influence on live tissues of dogs. Incisions were made in the liver, and ulcers in the dogs' stomachs were treated. The fibers were inserted into the stomach through the esophagus. Complete healing was observed after 4 weeks.
Protection of fiber function by para‐Axial fluid flow in interstitial laser therapy of malignant tumors
Authors: Dowlatshahi Kambiz , Bangert Julee D. , Haklin Michael F. , Rhodes Charles K. , Weinstein Ronald S. , Economou Steven G.
Published: March 2007

In the past, interstitial laser therapy frequently has failed because of the damage to the bare fiber tip due to intense heat generated at the point of contact. Using a rat mammary tumor model, we describe a method of placing a 600 micron fiber inside a gauge 19 needle cannula after its insertion into the tumor. With this device continuous wave Nd:YAG laser is delivered to the target tumor while 0.9% saline flows para‐axially into the tumor. Significant coagulation necrosis was induced with 500 joules at 5 watts, 100 seconds and 1 cc per minute of saline while the needle‐fiber is pulled out of the tumor by 10 mm. The mean transmission loss after 500 joules was 2% in ten experiments. The tumor edema due to 1.5 ml of saline was transient. We conclude that successful hyperthermic coagulation necrosis by Nd:YAG laser can be achieved with minimal transmission loss by employing the above technique.
Photochemotherapy of hypervascular dermal lesions: A possible alternative to photothermal therapy?
Authors: Orenstein Arie , Nelson J. Stuart , Liaw Lih‐Huei L. , Kaplan Ross , Kimel Sol , Berns Michael W.
Published: March 2007

Continued improvement in the results of laser treatment of port wine stain, with reduction in scarring, will depend on the ability to use lasers to induce selective injury of only the abnormal blood vessels in the dermis while sparing the normal overlying epidermis. Photodynamic therapy, using an exogenous photosensitizing drug specifically activated by certain wavelengths of light, may be used to destroy selectively certain targets in biological systems. The current study demonstrates, in the chicken comb model, that photochemotherapy can be used to treat hypervascular dermal lesions while leaving the normal overlying epidermis completely intact.