Safety and efficacy of a new high power argon plasma coagulation system (hp-APC) in lesions of the upper gastrointestinal tract

BACKGROUND: The aim of this study was to analyze safety and efficacy of a new high power argon plasma coagulation system in the upper gastrointestinal tract. METHODS: Data of 215 patients treated with a high power argon plasma coagulation system in the upper gastrointestinal tract 04/2003-01/2004, using a VIO APC device (VIO 300 D with APC 2; Erbe Elektromedizin, Tübingen, Germany; pulsed argon plasma coagulation, 20-120 W), were reviewed and analyzed. Indications were as follows: additive ablation therapy in curative treatment of early Barrett's cancer (122 patients); palliative treatment of oesophageal cancer (n=27); gastric adenoma/carcinoma (n=19); Zenker's diverticulum (n=8); and other. In 190/215 patients (149 males; mean age 67 years), the data were completely analyzable. Minor and major complications were evaluated. RESULTS: Minor complications (odynophagia, pain, fever) occurred in 24/277 sessions (8.7%); major complications (stenosis) in 3/277 sessions (1.1%) using at least 50 W. No perforation or bleeding occurred. The mean number of treatment sessions required was 1.46 (1-7); in the palliative treatment of oesophageal cancer, it was 2.5 (1-5). CONCLUSIONS: The high power argon plasma coagulation system was effective and safe in various gastrointestinal conditions. Due to it's high effectiveness and a low number of sessions required in tumour debulking, this high power argon plasma coagulation system might be used as an alternative to Nd:YAG laser.     

Quantitation of colonic injury from argon laser, neodymium: YAG laser and monopolar electrocautery applied to flat mucosa and small sessile polyps of the canine colon

This study determined the optimum laser energy for ablation of colonic mucosal lesions and small sessile polyps in the canine colon. Neodymium (Nd):YAG laser, argon laser, and monopolar electrocautery were applied to exposed canine colonic mucosa for various application times at various power settings. At the minimum energy level necessary to ablate mucosa, the Nd:YAG laser caused greater muscularis injury than the argon laser and monopolar electrocautery. At higher energy levels, monopolar electrocautery and Nd:YAG laser caused greater muscularis injury than argon laser. Small surgically created polyps in the canine colon were ablated endoscopically with the three energy sources. Single-session complete polyp ablation occurred most frequently with Nd:YAG laser and least frequently with argon laser. The depth of tissue injury beneath polyp ablation sites was least with argon laser and greatest with Nd:YAG laser. This study suggests that the argon laser is safer than the Nd:YAG laser or monopolar electrocautery for coagulation of flat colonic mucosal lesions. Although the argon laser is safer for the coagulation of small sessile colonic polyps, it may be less effective than monopolar electrocautery or the Nd:YAG laser for the single-session fulguration of polyps greater than 5 mm in diameter.     

氩离子凝固术对食管黏膜损伤的探讨

目的 探讨内镜下氩离子凝固术(APC)对食管黏膜的损伤程度。方法 在11例食管癌患者接受外科手术时,分别对其癌旁食管黏膜组织按不同功率(45 W、60 W、90 W)和不同时间(1s、3 s)进行APC烧灼。APC探头离黏膜组织约2 mm,呈约30°角,烧灼后的组织分别用光镜、电镜观察细胞及其超微结构,判断损伤程度。分析损伤程度与功率、时间的关系。结果 在55处APC烧灼后的组织切片标本中,46处仅累及黏膜层或黏膜下层,7处累及肌层,2处穿透全层。损伤深度与功率有关(P<0.01),与持续时间无明显关系(P>0.05)。结论 APC在内镜下治疗食管疾病时须将能量控制在一定范围以保证治疗的安全。     

Prospective evaluation of a new high-power argon plasma coagulation system (hp-APC) in therapeutic gastrointestinal endoscopy

OBJECTIVE: The aim of this study was to prospectively evaluate a new high-power argon plasma coagulation system (hp-APC) in therapeutic gastrointestinal (GI) endoscopy. MATERIAL AND METHODS: From February to June 2005, 216 patients (167 M (77.3%), mean age 66 years) underwent treatment with hp-APC in a total of 275 sessions. Main indications were additive ablation therapy in Barrett's esophagus, palliative treatment of esophageal cancer, gastric polyps/carcinomas, angiodysplasias, Zenker's diverticula, and duodenal adenomas. The new hp-APC device (VIO 300 D with APC 2) was used (15-120 W) in upper GI endoscopy, push-enteroscopy, and double-balloon enteroscopy. RESULTS: The mean number of treatment sessions required was 1.7 (1-5). For palliative tumor ablation in the esophagus, the number of sessions was 2.3 (1-5). Minor complications (pain, dysphagia, neuromuscular irritation, asymptomatic gas accumulation in the intestinal wall) were observed in 29/216 patients (13.4%). Major complications (perforation, stenosis occurred) in 2 patients (0.9%). CONCLUSIONS: Hp-APC appears to be safe and effective in the treatment of various GI condition using different types of endoscopes including double-balloon enteroscopy. Because of the low number of treatment sessions required, hp-APC could be used as an alternative to Nd:YAG laser treatment in tumor debulking.     

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.     

Laser catheter ablation of atrial flutter and of atrioventricular nodal reentrant tachycardia in a single session

This report describes an adolescent with refractory atrial flutter(AF) and atrioventricular (AV) nodal reentrant tachycardia whowas cured by Nd: YAG, 1064 nm, laser application. Two impactsof 30 s each (power 30 W and irradiated spot diameter 2.0–2.5mm), applied via a novel laser catheter system, abolished bothAF and AV nodal reentrant tachycardia. The procedure was withoutcomplications or recurrent arrhythmias.     

Argon vs. neodymium YAG laser photocoagulation of experimental canine gastric ulcers

A neodymium YAG (Nd:YAG) laser was evaluated in a dog ulcer model used in the same manner as is recommended for bleeding patients (power 55 W, divergence angle 4 degrees, with CO2 gas-jet assistance). The experiments were performed during sterile laparotomy in heparinized dogs. Bleeding gastric ulcers were photocoagulated until bleeding stopped and then examined histologically 7 days later when depth of tissue injury was maximal. In the first series of experiments, the Nd:YAG laser was compared with the 7-W argon laser in the same dogs. Both lasers stopped bleeding from all experimental ulcers. The 55-W Nd:YAG laser caused full-thickness injury to the gastric wall beneath 11 of the 14 treated ulcers, whereas the 7-W argon laser caused no full-thickness injury beneath 14 treated ulcers. In a second series of experiments, we tried to determine whether varying exposure times with the 55-W Nd:YAG laser would make it less injurious; it did not. In a third series of experiments, the 55-W Nd:YAG laser was tested with and without CO2 gas-jet assistance in order to determine if this would affect the depth of injury; it did not. In the final series of experiments, the wattage of the Nd:YAG laser was varied to see if this would reduce depth of injury; lower wattage did not stop bleeding, and intermediate and higher wattages did stop bleeding but did not reduce depth of injury. We conclude that the 55-W Nd:YAG laser as it is currently used clinically produces deeper tissue damage than the argon laser in our animal model. This damage is not reduced by changes in power, duration of exposure, or the presence of gas-jet assistance.     

Second-generation argon plasma coagulation: two-center experience with 600 patients

Background and Aim:  Second-generation argon plasma coagulation (APC; APC 2/VIO APC) with its modes 'forced', 'pulsed', and 'precise' is a further development of the ICC/APC 300 system (first-generation APC). Until now, only limited data has existed on the use of APC 2.
Methods:  Fundamental data on the characteristics of the various APC 2 modes and clinical data from more than 600 patients treated in two high-volume endoscopy centers were analyzed. On the basis of these data, recommendations for the use of APC in daily gastroenterological practice were made.
Results:  In comparison to the ICC system, second-generation APC offers a broadened bandwidth of settings including different APC modes and a range of power settings from 1 to 120 W. Using the various modes of APC 2 in a variety of gastrointestinal diseases, minor complications were observed in 9–21% of patients. Major complications occurred in 1–7% of patients.
Conclusions:  In a two-center experience treating a large group of patients with a wide variety of gastrointestinal conditions, the different APC 2 modes appeared to be safe and effective. Certain preventive measures before and during clinical application are recommended in order to avoid complications.     

New haemostatic techniques: argon plasma coagulation.

Bleeding is one of the main challenges for endoscopists. Despite a large number of methods for haemostasis, several types of haemorrhage lack an adequate therapeutic remedy. Argon plasma-coagulation (APC), a new method for the non-contact application of high-frequency current, promises to solve many of these problems. Among 1164 patients treated in 2349 sessions using APC, the indication was bleeding (due to tumour, intervention, angiodysplasia or coagulation disorders) in 305 patients (26%). The primary success rate was over 99%, the rebleeding rate 1.6% and the complication rate less than 1%, with zero mortality. Physical principles, indications, application parameters and results are discussed, especially in comparison with the Nd:YAG laser. APC is a new, efficacious, safe and easy-to-use method for the devitalization of tissue and haemostasis, especially in problematic cases.     

The influence of 15(R)-15 methyl PGE2, methyl ester, on Nd:YAG laser-induced gastric ulcers

The effect of 15(R)-15 methyl PGE2 on the evolution of gastric ulcers induced by endoscopic Nd:YAG laser photocoagulation was studied. By continuous application of 50 to 70 watt power for 4 sec at a distance of 15 mm from the gastric mucosa, reproducible ulcers can be induced. The effect of the drug in nonantisecretory doses (10 micrograms/kg) on the acute ulcer formation and on the healing rate was evaluated in mongrel dogs by light microscopy. Local administration or oral pretreatment did not influence the size or depth of acute ulcers (7.4 mm in diameter) as compared to a control series (7.2 mm). Pretreatment for several days, however, had a marked beneficial effect on the healing rate of the ulcers (1.71 mm after 7 days compared to 2.76 mm for the control series). From these data it may be concluded that 15(R)-15 methyl PGE2 has a beneficial effect on ulcer healing, even in nonantisecretory doses.     

Prospective evaluation of a new high-power argon plasma coagulation system (hp-APC) in therapeutic gastrointestinal endoscopy

Objective. The aim of this study was to prospectively evaluate a new high-power argon plasma coagulation system (hp-APC) in therapeutic gastrointestinal (GI) endoscopy. Material and methods. From February to June 2005, 216 patients (167 M (77.3%), mean age 66 years) underwent treatment with hp-APC in a total of 275 sessions. Main indications were additive ablation therapy in Barrett's esophagus, palliative treatment of esophageal cancer, gastric polyps/carcinomas, angiodysplasias, Zenker's diverticula, and duodenal adenomas. The new hp-APC device (VIO 300 D with APC 2) was used (15–120 W) in upper GI endoscopy, push-enteroscopy, and double-balloon enteroscopy. Results. The mean number of treatment sessions required was 1.7 (1–5). For palliative tumor ablation in the esophagus, the number of sessions was 2.3 (1–5). Minor complications (pain, dysphagia, neuromuscular irritation, asymptomatic gas accumulation in the intestinal wall) were observed in 29/216 patients (13.4%). Major complications (perforation, stenosis occured) in 2 patients (0.9%). Conclusions. Hp-APC appears to be safe and effective in the treatment of various GI condition using different types of endoscopes including double-balloon enteroscopy. Because of the low number of treatment sessions required, hp-APC could be used as an alternative to Nd:YAG laser treatment in tumor debulking.     

Nd:YAG laser in treatment of seriously ill patients with gastrointestinal bleeding

Nd:YAG (neodymium:yttrium aluminum garnet) laser coagulation was used to treat 30 seriously ill patients with massive or prolonged gastrointestinal bleeding. An average of 7.5 units of blood was given prior to Nd:YAG laser treatment. Twenty patients showed no evidence of continued or recurrent bleeding after laser therapy, four patients rebled after 48 hours, three patients rebled within 48 hours, one patient continued to bleed despite the laser treatment but died of an unrelated cause, one patient required immediate surgery because of inability to control bleeding, and one patient died several hours after control of the bleeding. Although six patients died within 10 weeks, no patient exsanguinated. Nd:YAG laser treatment is a useful modality for controlling severe gastrointestinal bleeding in the seriously ill patient.     

Argon plasma coagulation in bronchology: a new method--alternative or complementary?

Argon plasma coagulation (APC) is a thermal coagulation technique that uses ionized argon to transmit high-frequency electrical current, contact free, to tissue. APC has been used in surgery for more than 20 years, particularly for the hemostasis of superficial bleeding. Although APC has become well established in gastrointestinal endoscopy since its introduction in 1991, very few reports of its use in bronchoscopy exist to date. From June 1994 to June 1998, 364 patients (80 women, 284 men), 88% with a confirmed malignant tumor, were treated prospectively in a total of 482 sessions. The single most common indication was recanalization of malignant airway stenoses (186 patients). The defined therapy objective was achieved with good results in 67% of patients. More than 90% of interventions were performed with rigid bronchoscopy. Despite less penetration compared with Nd:YAG laser, extensive bronchial tumors were treatable, in which coagulated tumor fractions were removed either with forceps or bronchoscope tip. The second indication was bleeding in the central airways (119 patients). Acute hemostasis was achieved in 118 patients, 20% in whom the flexible technique under local anesthesia was used. In 34 patients, APC was successfully used to recanalize occluded stents. Rare indications included benign endobronchial tumor, fistula conditioning before fibrin adhesion, and the treatment of scar tissue stenosis. Summarizing all complications, a rate of 3.7% "per treatment" was recorded. Two patients died within 24 hours; their deaths were not directly related to APC. APC is an effective and safe technique for the treatment of bronchologic tumor ablation and hemostasis and can be used with local anaesthetic with flexible bronchoscopy or rigid bronchoscopy with general anesthesia. Compared with Nd:YAG laser, APC is an economic alternative technique offering more effective hemostasis. Furthermore, APC is of particular value as a compliment to well-known techniques, increasing the options in interventional bronchoscopy.     

In vivo evaluation of argon plasma coagulation in a porcine model

BACKGROUND: Argon plasma coagulation (APC) is a noncontact form of monopolar electrocautery. One purported advantage of APC includes a limit to the depth of injury. It is unclear from previous studies whether the depth of injury is limited to superficial tissue layers with the settings used in clinical practice. OBJECTIVE: To evaluate the depth and the area of APC-induced injury by using new modes of APC delivery in an in vivo porcine model in the setting of colonoscopy. DESIGN: Blinded quasi-experiment. SUBJECTS: Six swine. INTERVENTION: Colonoscopy with the swine under general anesthesia, with application of APC in 2 different pulsed modes and varying power settings and duration of application. MAIN OUTCOME MEASUREMENTS: Surface area and depth of colonic mucosal injury. Qualitative histologic analysis of each site of APC application was performed on formalin-fixed specimens after euthanizing the swine. RESULTS: Muscularis propria injury occurred in 22% of lesions with 10 W, 62% of lesions with 20 W, 86% of lesions with 40 W, and 80% of lesions with 60 W. Muscularis propria injury occurred in 42% of lesions at 1 second, 66% of lesions at 3 seconds, and 69% of lesions at 5 seconds. Depth of injury was significantly correlated with total energy delivered (P = .001, r = 0.75). Surface area was significantly associated with total energy delivered (P < .001, r = 0.81). LIMITATIONS: This study was performed in distal swine colon rather than human colon. Colon tissue response to APC injury may differ from swine to human colon. The application distance from the APC probe to the colonic tissue may have varied between applications. CONCLUSIONS: Muscularis propria injury occurs across a broad range of clinically used APC settings. The frequency of deep injury and the surface area of the lesion increases with total energy delivered. The lowest power settings (10-20 W) and the shortest durations have the lowest risk of deep tissue injury.     

A two-year experience with the neodymium-YAG laser in endobronchial obstruction

In the first two years after the introduction of neodymium-yttrium-aluminum-garnet (Nd: YAG) laser therapy to our practice, 116 patients were treated 176 times. One hundred six patients (91.4 percent) were treated with the flexible fiberoptic bronchoscope. General anesthesia was used in 89.7 percent of treatments; there were four transient anesthetic complications. Three deaths from massive hemorrhage occurred in the first 59 treatments (first 30 patients). After laser power settings were reduced from 90 to 40 W, there were no further incidences of massive hemorrhage or death in the subsequent 117 treatments. The airway caliber was improved in 83.4 percent of treatments. The trachea, mainstem bronchi, and bronchus intermedius airway calibers were improved more often than those of the lobar bronchi. With lower laser power settings, Nd:YAG laser therapy is a safe and effective means of relieving airway obstruction. Thirty-six percent of patients were alive at one year. The median time to retreatment or death was 130 days.     

Low-Power Contact Nd: YAG Laser Endoscopy

Abstract: Laser application in gastrointestinal endoscopy started with the development of flexible optical fibers in about 1970. Originally, non-contact irradiation with high power Nd: YAG lasers of 100 watts (W) was used for gastrointestinal hemostasis. It was difficult to achieve safe and reliable irradiation with this method, the quarts fiber tips were susceptible to coagulation damage, and the cost was high. As a result local injections were recognized as an inexpensive and excellent method of producing hemostasis, and became the treatment of first choice. Therefore, the endoscopic use of lasers shifted from hemostasis to the topical treatment of tumors. In 1984 low-power Nd: YAG laser irradiation at 1 to 30W became possible using a ceramic contact probe co-developed by the authors and the Surgical Laser Technology Japan Co. This made photocoagulation, vaporization, cutting and local hyperthermia (Laserthermia) feasible. Improvements in laser irradiation efficiency led to the development of inexpensive equipment, costing less than one-third of the price of conventional equipment. The application of low-power contact lasers significantly improved the clinical efficacy of the treatment of minute cancers, but the technique has the same limitations as other endoscopic methods. Furthermore, because laserthermia is still being developed, the best technique has not yet been fully defined. In the future, treatments that can be used effectively in association with low-power contact laser therapy need to be identified. Low-power contact laserthermia, local hyperthermia with microwaves, and photodynamic therapy with excimer dye lasers all need to be studied further. This will contribute to the development of a minimum invasive therapy for gastrointestinal lesions.     

Catheter-directed laser coagulation of atrial myocardium in dogs

The feasibility of transcatheter laser coagulation of atrialmyocardium was tested in a canine model by using a combinedelectrode-laser catheter. In 17 anaesthetized beagles a totalof 264 lesions, 12–19 per dog, and 3–5 in each areawere produced in: (1) the lateral walls, (2) the posterior rightatrial walls, (3) the inter-atrial septum, and (4) the atrialappendage. The power source was a continuous wave Nd: YAG laser.Irradiance was 1 kW. cm^–2, at a wave length of 1064 nm,the irradiated spot diameter was 2.0–2.5 mm, and the pulseduration 5–60 s. Local intra-cardiac atrial potentialsrecorded from the targeted areas during laser irradiation dwindledafter onset of the laser pulse, and their amplitude was reducedpersistently by pulses of 15 s or longer. Histopathologically,the acute lesions showed intramural haemorrhage and coagulationnecrosis, but there was no tissue vaporization or crater formation.Chronic lesions showed clear-cut oval-shaped areas of transmuralfibrosis. Diameters of lesions, dependent on the amount of laserenergy applied, measured from 4.6 ± 0.5 mm (450 J) to7.8 ±1.4 mm (1800 J). Follow-up lasted 6–25 months(average 10.5). All the animals survived the procedure withoutcomplications. Transcatheter laser coagulation of atrial myocardium is safeand can be performed in a controllable manner by using the cathetersystem presented.     

A new model to study quantitative effects of laser angioplasty on human atherosclerotic plaque

A new model for analyzing the major effects of the use of any laser angioplasty system is described. Changes in any of the six major determinants of effect (energy, duration, wavelength, medium, absorption, geometry) can be evaluated. In this report a neodymium: yttrium aluminum garnet (Nd:YAG) laser was used to make 408 laser exposures in vitro on segments of human cadaveric atherosclerotic aorta. Energy, medium (air, human blood, perfluorochemical and saline), geometry and duration were varied. The depth and width of the resultant plaque craters were measured. A large amount of exposure to exposure variability was found in all groups of experiments, even when conditions were held as constant as possible in this rigidly controlled laboratory setting. This variability is attributable to differences in energy absorption by the plaque. Changes in media and fiber optic tip to plaque distance also markedly altered exposure outcome. For example, the average depth of the hole created by a 15 W, 2 second blast with the fiber tip adjacent to the plaque in blood was 1.7 +/- 0.1 mm (n = 27), but the range was between 0.5 and 2.7 mm. Under the same conditions, except with the fiber tip 1 mm away from the plaque, the average hole depth was 0.4 +/- 0.1 mm (n = 12) and the range was 0.0 to 1.7 mm. The use of this model to analyze the major determinants of lasing effects in different laser angioplasty systems should help to select the best conditions for lasing and allow assessment of the variability of outcome.     

AMI犬TMLR术后心肌血流量变化及意义

目的 本实验观察了激光心肌血管重建术(TMLR)后心肌血流量的变化,探讨TMLR的作用机制。方法 18只犬随机等分为三组:A组-对照组;B组-缺血组;C组-激光组。采用连续型Nd:YAG激光行心肌打孔,光纤直径0.6mm,功率20～25W,脉冲时间0.3～0.5s,孔间距离8～10mm。于LAD结扎前、结扎后30min和60min收集冠状静脉窦血计算心肌血流量。统计学处理采用随机区组设计的方差分析(α=0.05)。结果 缺血组LAD结扎后心肌血流量进行性下降(P<0.05),而激光组LAD结扎前后比较无显著性差异(P>0.05),但结扎后明显高于缺血组(P<0.05)。结论 TMLR可迅速有效地改善心肌缺血。     

Photodynamic Therapy Using a New Photosensitizer Gallium Porphyrin Complex in the Treatment of Experimental Pancreatic Cancer

Abstract: To determine the therapeutic effect of photodynamic therapy (PDT) using a new photosensitizer 2.4-bis (1-decyloxyethyl)-Ca-deuteroporphyI diaspartic acid (Ga -DP), 20 female Syrian golden hamsters with experimentally induced pancreatic cancer were irradiated with a pulsed Nd : YAG laser with a Q switch after administration of Ga -DP. To induce pancreatic cancer, N-nitroso-bis-(2-oxypropyI) amine (BOP) at 10 mg/kg body weight was injected subcutaneously once a week for eight weeks. Ten of the twenty animals served as a control group. The other ten received laser treatment beginning 20 weeks after BOP administration. Twenty-four hours after intravenous injection of 3 mg/kg Ga-DP, pulsed Nd : YAG laser irradiation was performed using a Q switch with 1 W of power output for 3–5 minutes at a frequency of 300 Hz. Elimination or necrosis of the entire tumor resulted with tumors 6–10 mm in diameter in 6 animals. In 3 animals which had tumors more than 12 mm in diameter, cancer cells remained at the margins of the treated area. These results were felt to not only reflect the thermal effect of laser therapy, but also the effect of PDT combined with Ga-DP. They suggest that Ga-DP could become a clinically valuable photosensitizer in combination with PDT. (Dig Endosc 1994; 6 : 28–33)