Contact neodymium: YAG laser surgery in gastroenterology

Summary Eighty-eight patients have been successfully treated endoscopically without complications using contact neodymium yttrium aluminum garnet: (YAG) laser probes (endoprobes) for tumors and bleeding and during open surgery (laser scalpel) to perform hepatic and pancreatic resections. The contact probes, made from a synthetic sapphire crystal with its optical properties, geometric design, thermal conductivity, and high melting temperature (2030 °C), have proven to be more effective than the current conventional noncontact method of delivering laser energy through a quartz fiber. Advantages include greater precision, sterility, avoidance of the tip melting, and lower neodymium: YAG laser energy required, resulting in reduced tissue damage. The configuration of the probes allows coagulation, cutting, or vaporization, depending on the clinical condition being treated.     

Contact neodymium:YAG laser surgery in gastroenterology: a preliminary report

Fifty-four patients have been successfully endoscopically treated without complications using contact neodymium:YAG laser probes (endoprobes) for tumors and bleeding and, during open surgery (laser scalpel), for liver and pancreatic resections. The contact probes made from a synthetic sapphire crystal with its optical properties, geometric design, and thermal conductivity have proven to be more effective than the current conventional noncontact method of delivering laser energy through a quartz fiber. Advantages include greater precision, sterilizability, avoidance of the tip melting, and a requirement for lower neodymium:YAG laser energy with reduced tissue damage. The configuration of the probes allows coagulation, cutting, or vaporization, depending on the clinical condition being treated.     

Urologic neodymium: YAG laser surgery

The advantages of each of the laser types used in urologic surgery are discussed and evaluated. Use of the Nd:YAG laser in urologic surgery is a recent advancement.     

Renal preservation utilizing neodymium:YAG laser

Six patients with malignancies in a solitary kidney were treated with conservative renal parenchymal-sparing surgery utilizing the Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser. Three patients had transitional cell carcinoma in an upper pole calyx of a solitary kidney. The transitional cell carcinoma was treated definitively by the Nd:YAG laser through a nephroscope prior to partial nephrectomy. The 3 patients have been followed up for twenty-eight, eighteen, and six months, respectively. None of the patients has shown evidence of recurrent cancer on follow-up retrograde ureterograms or on urine cytology obtained from the renal pelves. Three patients with renal cell carcinoma in a solitary kidney had the tumor surgically excised utilizing the Nd:YAG laser in conjunction with standard surgical techniques. All the patients were elderly with compromised renal vasculature that prevented bench surgery with autotransplantation or occlusion of the renal artery. At sixteen, fourteen, and three months, respectively, there is no evidence of recurrent cancer on CAT scans obtained on these patients.     

Safety of high-energy neodymium:YAG laser pulses in YAG sclerostomy

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.     

Use of neodymium YAG laser in endoscopic hemostasis in thoracic surgery]

YAG-laser radiation was used for endoscopic hemostasis in 33 patients with bleeding endobronchial carcinomas and in 4 patients with chest injury complicated by bleeding from wounds of the lung and chest wall. For conducting laser photocoagulation, the authors prefer a rigid bronchoscope and a thoracoscope and pulsed laser radiation with a power of up to 40 Wt. As the results of treatment, hemostasis was achieved in 24 patients with lung carcinoma and in 4 patients with trauma of the chest. In some patients with pulmonary carcinoma laser photocoagulation creates conditions for successful surgery or chemoradiotherapy. The performance of thoracoscopic laser operations in chest injuries and traumas allows wide thoracotomy to be avoided in some patients. Complications were not registered in endoscopic laser operations.     

Transscleral cyclocoagulation using a neodymium:YAG laser

A series of pigmented rabbit eyes were treated with pulsed 10 msec (free running mode) neodymium:YAG laser burns to achieve transscleral cyclocoagulation. Grossly evident burns were created in the ciliary body with laser pulses of 1.5 joules of energy. Sustained reduction in intraocular pressure was obtained when 30 such laser burns were made in an eye.     

Treatment of urethral diseases with neodymium:YAG laser

Over a thirty-month period, a wide variety of common urethral problems were treated on an ambulatory basis, with the neodymium:yttrium-aluminum garnet (Nd:YAG) laser. When used discriminately, laser treatment appears to be an effective modality for the management of selected urethral strictures. Thus far, excellent results have been obtained in 30 of 31 cases of short strictures where laser urethrotomy was performed as the first stricture procedure (average follow-up 10 months). Furthermore, in a series of 36 cases of secondary bladder neck contractures, all of the evaluated patients responded well (average follow-up 7 months). Good results were obtained in only 11 of 48 complicated strictures (average follow-up 14 months). However, while most of these extensive strictures were not eradicated, laser therapy generally produced a documented clinical improvement, comparable to urethrotomy or dilatation, in 15 of these cases. A series of 24 condylomata involving the urethra were treated satisfactorily, with no recurrences (average follow-up 13 months). Laser treatment also has been used successfully for the management of several urethral caruncles, urethral polyps, two meatal hemangiomas, one urethral carcinoma, and a distal duplicated urethra. Recently, the Nd:YAG laser has been applied to the prostatic urethra with vaporization of obstructing median bar hyperplasia. Favorable results have been achieved in 5 of 6 cases treated with a newly developed technique that utilizes direct laser contact. Retrograde ejaculation has not been encountered in these patients (average follow-up 6 months). All of these procedures have been accomplished in the office, largely without urethral catheterization. Lidocaine jelly occasionally supplemented with intravenous sedation provided satisfactory anesthesia.     

Intraocular lens design for the neodymium:YAG laser

Phacoemulsification was performed on both lenses of 24 rabbits. One eye received a lens implant with a convex-plano optic; the fellow eye received an implant with a convex-concave optic which separated the posterior surface of the implant from the posterior capsule by 0.2 mm, 0.3 mm, or 0.4 mm. A YAG laser capsulotomy was performed on all eyes immediately following surgery and an assessment of both microscopic and macroscopic YAG-induced lens damage was made. The meniscus optics with their capsule-implant separation showed significantly less YAG-induced damage than their convex-plano counterparts without this separation. Increasing the amount of capsule-implant separation beyond 0.2 mm did not enhance the degree of protection from YAG-induced damage.     

A new contact neodymium:YAG laser for cyclophotocoagulation

A newly developed compact (40 kg), self-contained contact Neodymium:YAG laser produces high-peak, high-energy (800 mJ/pulse), short (1.0 millisecond) pulses with 1 to 3 pulses/exposure. Energy is delivered via a 320-microns cleaved quartz fiber optic probe. Cyclophotocoagulation was performed in five eyes of three medium-sized Dutch-pigmented rabbits. The eyes received exposures of 1 to 3 pulses/exposure. Energy delivered ranged from 100 to 800 mJ/pulse. Histopathology revealed ciliary body disruption and hemorrhage with no damage to overlying sclera. When used for transscleral cyclodiathermy in the rabbit, the laser created significant ciliary body disruption with minimal scleral injury.     

Transscleral neodymium: YAG laser cyclocoagulation for uncontrolled glaucoma

To determine the efficacy and safety of the procedure, we reviewed the records of 25 eyes of 25 patients who had received noncontact transscleral Nd:YAG laser cyclocoagulation for a variety of uncontrolled glaucomas. Thirteen to 35 pulses (mean, 22.7 pulses) had been placed 1 mm to 2 mm behind the limbus with an energy per pulse of 3.4 J to 8.2 J (mean 4.5 J). Follow-up ranged from 6 months to 23 months, with the exception of one eye, which had to be enucleated. Nine of the 25 eyes (36%) required one or two repeat treatments. Twelve (48%) had intraocular pressures at last follow-up of less than 21 mm Hg but greater than 4 mm Hg. Ten eyes (40%) developed moderate to severe pain transiently, and 10 (40%) developed substantial, but transient, inflammation. Transscleral Nd:YAG laser cyclocoagulation appears to be relatively effective and well tolerated.     

Laser lithotripsy with the neodymium YAG laser

Laser-induced shock wave lithotripsy (LISL) with a Q-switched neodymium-YAG laser depends on the generation of a laser-induced breakdown in the fluid surrounding the stone. An oscillating plasma bubble is created, directing shock waves towards the stone. These cavitational effects fragment the calculus into small particles. A new bifunctional laser is introduced: this allows both nanosecond pulses for shock wave generation and disintegration of urinary calculi and millisecond pulses for biliary stones and tissue coagulation. It can be supplied with 320-, 400-, and 600-micron fibers. We have treated 189 ureteric stones in 185 patients with laser lithotripsy utilizing flexible ureteroscopes (n = 26) or rigid ureteroscopes (n = 159). It proved possible to fragment 179 stones into small pieces. In eight patients LISL was not successful. A rigid cystoscope that can be dismantled into an upper and lower hemisheath for the introduction of flexible endoscopes into the ureter without prior dilatation of the ureteral orifice was used in 15 patients.     

Transscleral cyclophotocoagulation using a neodymium YAG laser

The effects of a neodymium: YAG laser, working in the free-running mode (1 and 20 millisecond pulses), upon the ciliary body via the transscleral route have been studied using 16 autopsy eyes. The experiments described were designed to find an efficient strategy of transscleral cyclodestruction of the ciliary body. It was found that pulse energies of between 6 and 7 Joules, an exposure duration of 20 milliseconds, and maximal defocusing are optimal. A beam, tangentially oriented and positioned 1/2 to 1 mm posterior to the limbus has a high probability of hitting the ciliary body and damaging the ciliary processes. In these experiments a first generation of contact lenses could not be demonstrated to have an advantageous effect.     

Ab-interno neodymium:YAG versus erbium:YAG laser sclerostomies in a rabbit model.

This study was undertaken to determine whether thermally-induced tissue necrosis was a factor in ab-interno contact-laser sclerostomy failure. A rabbit model was used to compare the continuous-wave Neodymium (Nd):YAG with the pulsed Erbium (Er):YAG laser with respect to such failure. Laser energy was focused into a fused-silica fiber optic (400 microns) for the Nd:YAG laser (12 W; 3 to 5 seconds), and into a single-crystal, uncladded sapphire fiber optic (250 microns) for the Er:YAG laser (7 to 8 mJ; 250 microseconds; 6 to 8 pulses). The Nd:YAG and Er:YAG lasers required from 21 to 35 J and from 42 to 64 mJ, respectively, to create the sclerostomies. Filtering blebs and intraocular pressure reduction lasted longer (log-rank test; P less than .03) and surgical complications were fewer in the Er:YAG group than in the Nd:YAG group. By creating sclerostomies with minimal thermal damage, the Er:YAG laser may offer significant clinical advantages over lasers producing larger thermal effects.     

Endoscopic neodymium: YAG laser treatment of radiation-induced hemorrhagic cystitis

Hemorrhagic cystitis is a debilitating complication of radiation therapy for pelvic malignancy. Forty-two such patients with intractable hematuria underwent endoscopic Nd:YAG laser coagulation under local anesthesia between January 1990 and July 1992. The laser power was kept at ? 30 W and the pulse duration ? 3 s. Control of bleeding was achieved in 39 patients after one sitting and in 2 patients after two sittings of laser treatment. There were no complications of the procedure and recurrence of bleeding was not seen in any of the patients achieving CR at a mean follow-up period of 14 months. With modifications in the safety guidelines, we recommend laser treatment as the initial procedure of choice in patients with hemorrhagic radiation Cystitis. © 1994 Wiley-Liss, Inc.     

Bactericidal effects of the neodymium:YAG laser: in vitro study

The effects of laser energy on three bacterial strains, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were studied utilizing the neodymium:YAG laser. Cell suspensions of each strain were divided into four groups. In group I, suspensions from each strain were exposed to laser energy densities of 555-3,333 J/cm2. In groups II and III, two artificial dyes, congo red or methylene blue, were added to the suspensions prior to lasing. In group IVa, no laser energy was used, and group IVb was used to measure the bactericidal thermal effects of the laser. It was concluded that: Low dosages of laser energy exceeding 1,667 J/cm2 resulted in a 2 to 8 log decline in the number of viable bacterial colonies in vitro. Compared to the other two bacterial strains, P aeruginosa was the most sensitive to YAG laser irradiation. Addition of methylene blue, a dark-colored dye, enhanced the bactericidal effects of the YAG laser as indicated by the significantly reduced viability of P aeruginosa after irradiation with 2,222 J/cm2.     

Carcinoma of penis treated with neodymium YAG laser

Sixteen men with squamous cell carcinoma of the penis were treated primarily with the Neodymium Yttrium Aluminum Garnet (Nd:YAG) laser. Five patients had TIS, 9 had T1 tumors, and 2 had T2 carcinoma. All patients had refused traditional therapy of partial penectomy and gave informed consent as to the investigational nature of the Nd:YAG laser photoradiation therapy. Circumcisions and deep tissue biopsies were performed on all patients prior to tumoricidal neodymium photoradiation treatment. The patients were followed from twelve to thirty-six months. At follow-up, 5 patients with TIS had no evidence of recurrent cancer. Of the 9 patients with T1 squamous cell carcinoma of the penis, 6 (67%) were tumor-free at a mean follow-up of twenty-six months. The 2 men with T2 carcinoma of the penis had reduction of the tumor mass but were not cured. The obvious advantage of the Nd:YAG laser in treating carcinoma of the penis is preservation of the penis eliminating disfiguring amputation.