Effects of Nd:YAG laser irradiation on ventricular myocardium in dogs using an artificial sapphire tip contact laser catheter]

To apply Nd:YAG laser irradiation through a new sapphire tip contact laser method to catheter ablation in treatment of tachy-arrhythmias, effects of laser irradiation on ventricular myocardium were investigated in 10 mongrel dogs. Nd:YAG lase (1064nm) discharges were delivered to different sites on the endomyocardium at power of 5, 10, 15, 20 or 25w with duration of 3, 5, or 10 seconds (sec.) respectively in closed beating hearts. Histopathologically, the lesion irradiated was clearly demarcated from the normal myocardium by the construction band necrosis zone. The depth of injured myocardium was less than 2mm with 3 sec. irradiations, with 5 sec. from 1 mm to 4 mm in proportion to power increase, with 10 sec. from 3mm to 8 mm in proportion to the power from 5w to 15w and could not be measured in cases of more than 20w irradiations. Although with every irradiation duration, the depth of injury increased in proportion to the power increase. With the same total energy, a longer time of irradiation produced deeper injury than a shorter time. This method makes it easier to keep the laser positioned to target than bare laser, and is suitable for use in catheter ablation.     

Nd:YAG laser with sapphire tip combined with balloon angioplasty in peripheral arterial occlusions. Long-term results.

In 167 patients with complete occlusion (greater than 3 cm) of the femoropopliteal artery, percutaneous transluminal laser angioplasty (PTLA) was performed after an unsuccessful attempt at crossing with a guide wire and was immediately followed by balloon dilatation. An Nd-YAG laser and an optical fiber delivery system with a sapphire tip serving as a contact probe were used for PTLA. In 132 of 167 (79%) patients, the occluded segment was successfully reopened. Clinical symptoms improved in 126 of 167 (75%) patients. PTLA was unsuccessful in 35 patients, and in 15 of these, injury of the vessel wall occurred. In one patient, surgical drainage of a large hematoma became necessary. All patients in whom recanalization had been achieved were randomized to receive long-term treatment with either phenprocumarol or acetylsalicylic acid (ASA) plus dipyridamole to prevent rethrombosis. At 36 months of follow-up, the cumulative patency rate (CPR) was 63%. A complete reobstruction in 32 patients (24%) and a partial reobstruction in 15 patients (11%) were found angiographically. The CPR after 36 months was significantly lower (p less than 0.05) in patients younger than 60 years of age (54%) than in patients older than 60 (68%); it was also significantly lower (p less than 0.05) in patients with reduced peripheral runoff (55%) due to obstructed arteries of the lower leg than in patients with unaffected runoff (73%). The CPR was 65% in recanalized segments shorter than 7 cm and was 62% in recanalized segments longer than 7 cm.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nd:YAG laser modulation of synovial tissue metabolism

In studies designed to establish the safety and efficacy of laser treatment of arthritis, the in vitro effect of Nd:YAG laser radiation on normal, osteoarthritic and rheumatoid synovial tissue and synovial fibroblast metabolism has been addressed. Defined energy levels of normal pulsed radiation (TEMoo mode) consistently up-regulated synovial tissue explant culture hyaluronic acid and protein synthesis. In contrast, high intensity Q-switched delivery down-regulated the response. The application of normal pulsed radiation had a variable effect on synovial fibroblast synthesis but the response of any given cell isolate was consistent. DNA synthesis and cell viability were not affected.     

Nd:YAG laser treatment of colorectal villous tumors

Fifty-eight patients, 23 men, 35 women (mean age 76 +/- 10 yrs), with colorectal villous adenomas underwent endoscopic neodymium Yag laser therapy. In 50 patients with interpretable results, tumor ablation was complete in 45 p. 100 of extensive adenomas involving at least two thirds of the circumference and extending longitudinally for at least 4 cm, in 92 p. 100 of intermediate adenomas between 1 and 4 cm in diameter and in 100 p. 100 of small adenomas with diameter less than or equal to 1 cm. These patients had a mean follow up of 72 weeks (range 13-182 wks). Twelve adenomatous tissue recurrences occurred in 9 patients. In 10 of these recurrences, laser ablation was effective. Age, sex, dysplasia grade, macroscopic appearance, or tumor location did not influence the results which were related to the size of the villous adenomas. Four complications occurred: a symptomatic stenosis, an asymptomatic stenosis, an ileocaecal fistula and a rectal fistula near a colorectal anastomosis.     

Nd:YAG laser in treatment of rectal cancer

In the present study we report the results of Nd:YAG laser treatment in 36 patients with rectal carcinoma in whom negative biopsies were obtained at the end of the treatment. The laser (100-W maximal power output) was applied through a flexible endoscope during 20- to 40-min sessions repeated every three days until the lesion was destroyed completely. Follow-up examinations, including endoscopy with biopsies, liver and endorectal ultrasonography and chest x-ray were performed every three months during the first year and thereafter once a year. Between 1980 and 1991, 272 patients were treated. All were unfit for surgery because of metastasis (78), recurrence after an other procedure (54), associated conditions, or old age (140). No circumferential tumors of any size were obliterated, but among the 139 patients presenting with a noncircumferential lesion less than 7 cm in diameter, negative biopsies were obtained after laser treatment in 36 patients (26%). Of these 36 patients, eight had been treated previously by surgery (5) or radiotherapy (3). Mean follow-up is 37 months (range 12–71). Recurrences were observed in four cases. Seven patients died during the study but only one death was related to the cancer (pelvic extension 19 months after treatment). Endorectal ultrasonography was performed prior to treatment in 15 patients and showed no invasion of the rectal wall deeper than the submucosa. After treatment, endorectal ultrasonography in 22 patients showed significant changes corresponding to cicatricial pattern in 60% of controlled patients. These changes disappeared by three months except in three patients in each of whom a echo-guided biopsy ruled out a local recurrence. No complication of laser therapy was observed in these 36 patients. Laser treatment is effective for noncircumferential carcinomas smaller than 7 cm in diameter and not deeply invading the rectal wall. Such therapy, however, seems most appropriate for patients who are unfit for surgery.     

Percutaneous laser angioplasty with a pulsed Nd:YAG laser. Initial clinical experience and early follow-up.

Percutaneous laser-assisted balloon angioplasty with a pulsed Nd:YAG laser coupled to sapphire tipped optical fibers was used for the treatment of 22 patients presenting with 30 chronic occlusions of peripheral arteries (mean length 11 cm) during 25 sessions. The procedure was completed by balloon dilatation in 67%. Successful recanalization was achieved in 92%, clinically the procedure was successful in 68% with mean ABPI increase from 0.43 +/- 0.13 to 0.79 +/- 0.21. In 8 cases complications occurred. Two reocclusions were treated by streptokinase infusion, and 2 procedures were repeated 2 months later, one patient was referred to elective bypass surgery, and 3 patients were treated conservatively. Six patients were followed-up for more than 6 months. In 1 patient claudication of 400 m reappeared. These results are encouraging and it is likely that this method could become an important adjunct to balloon angioplasty.     

Endoscopic Nd:YAG laser treatment of rectosigmoid cancer.

Forty nine patients with rectosigmoid carcinoma considered unsuitable for surgery underwent endoscopic Nd:YAG laser treatment for palliation of symptoms and tumour eradication, if feasible. Altogether 25 (51%) of the lesions had distal margins less than 7 cm from the anus and 36 (73%) extended above the peritoneal reflection. In seven patients with tumours less than 3 cm in diameter, symptomatic improvement was achieved in all (mean follow up 16 months) and complete tumour eradication in three. In the remaining 42 patients with larger tumours (34 greater than 2/3 circumferential, mean length 5.5 cm), symptomatic improvement was achieved with repeated treatments (average 3.4) in 31 (74%) over a mean follow up of 19 weeks. Of the parameters assessed, only circumferential tumour extent proved significant in predicting functional outcome after treatment. All treatment failures (eight initial, three late) occurred in patients with extensive tumours, and only seven of these patients were considered fit for colostomy. Bowel perforation occurred in two patients (5%) but there was no treatment-related mortality. Mean stay in hospital for all laser treatments was nine days (30% were outpatient attendances). These results suggest that laser therapy may be the palliative treatment of choice in patients with rectal carcinoma unsuitable for surgery.     

Endoscopic Nd:YAG laser therapy of infantile subglottic hemangioma

Of the many therapeutic modalities that have been developed for infantile subglottic hemangioma (ISH), the most common technique is endoscopic excision with carbon dioxide laser, used alone or combined with other therapeutic techniques. A staged procedure has been proposed as the preferred choice for patients with severe airway obstruction. Nevertheless, ever since the neodymium: yttrium-aluminum-garnet (Nd:YAG) laser was developed, this modality has been considered feasible to treat vascular tumor in the airway due to good hemostasis power. We present two cases of ISH with severe airway obstruction that underwent endoscopic surgery using an one-stage Nd:YAG laser approach. Details of the laser characteristics and surgery techniques are described in this article.     

Use of Nd:YAG laser in endobronchial Kaposi's sarcoma

An unusual case of endobronchial Kaposi's sarcoma causing right middle and lower lobe atelectasis is reported. The lesion was successfully removed with Nd-YAG laser photoresection.     

Palliation of rectosigmoid neoplasms with Nd:YAG laser treatment

PURPOSE: The aim of this study was to evaluate the effect of Nd:YAG laser treatment as palliation for rectosigmoid neoplasms. METHODS: Indications for laser therapy, the degree and duration of symptom relief, complication rate, and survival time were recorded in consecutive patients. RESULTS: Seventy-four patients entered the study. Poor general health in older patients, and disseminated or complicating disease were the most frequent indications for therapy. Fifty-five (74 percent) patients experienced good symptomatic effect from the treatment. Six complications occurred: five cases of perforation and one case of moderate bleeding. There was no mortality. The median survival was seven months (range, 14 days–39 months). CONCLUSION: Laser treatment is a good palliative method in patients with colorectal cancer, especially in patients with local recurrence or symptoms from nonresected tumors.     

Photodynamic therapy using pheophorbide-a and Q-switched Nd:YAG laser on implanted human hepatocellular carcinoma.

To evaluate whether administration of pheophorbide-a, a new photosensitizer, followed by use of Q-switched Nd:YAG laser produces a photodynamic reaction, we administered pheophorbide-a to female nude mice (BALB/c-nu) that had been implanted with human hepatocellular carcinoma. Intra-tumoral concentrations of pheophorbide-a were measured by high-performance liquid chromatography. 3 hours after peroral administration of 1 mg/kg body weight, the intra-tumoral concentration was too low to reveal photodynamic effects. Peroral administration of 250 mg/kg body weight, intra-peritoneal administration of 5 mg/kg body weight, and intra-tumoral injection of 200 micrograms yielded 0.24 micrograms/g, 0.83 micrograms/g and 3.68-108 micrograms/g tumor concentrations, respectively. All tumors were irradiated interstitially using a Q-switched Nd:YAG laser at 1064 nm. Only tumors that had been intra-tumorally injected had areas of necrosis larger than those in control tumors. The results suggest that the injection of pheophorbide-a followed by interstitial irradiation using a Q-switched Nd:YAG laser does not induce sufficient photodynamic reaction if the intra-tumoral pheophorbide-a concentration is less than 0.83 micrograms/g tumor tissue, and that photodynamic therapy may be useful if the pheophorbide-a tumor concentration is within the range of 0.83-108 micrograms/g.     

Palliation of oesophagogastric neoplasms with Nd:YAG laser treatment.

The palliative effect of endoscopic Nd:YAG laser treatment of malignant strictures of the oesophagus and cardia was prospectively evaluated in 30 patients. Most (n = 28) were primarily treated for dysphagia, and swallowing was improved in 21 and normalized in 14 of these patients. Two patients were successfully treated for bleeding. Six patients developed complications (including two perforations), and four of these were fatal. The median survival was 4 months (range, 17 days to 14 months). It is concluded that in a great number of patients with inoperable cancer of the oesophagus and cardia, laser treatment is better than other palliative procedures.     

In vitro effects of Nd:YAG laser radiation on cartilage metabolism

Laser therapy is being increasingly applied in the treatment of diverse forms of arthritis without a firm scientific basis for its safety or efficacy. Our study in part addresses this issue by assessing the in vitro effect of Nd:YAG laser radiation on mature normal bovine articular cartilage metabolism. Normal pulsed mode delivery of defined energy levels could be shown to consistently upregulate cartilage proteoglycan, collagen, noncollagen protein and DNA synthesis in the absence of histologic or biochemical evidence of enhanced matrix catabolism. Laser induced repair could be shown biochemically in in vitro model systems of enzymatically mediated cartilage matrix depletion. Results suggest that Nd:YAG radiation applied directly at surgery or via arthroscopy may provide a potential means of effecting cartilage healing. Further studies are necessary to substantiate such usage.