In vivo evaluation of argon plasma coagulation in a porcine model

Colorectal Endoscopic Submucosal Dissection: Performance of a Novel Hybrid-Technology Knife in an Animal Trial

Endoscopic submucosal dissection (ESD) was developed for the removal of benign and early malignant lesions in the gastrointestinal tract. We aimed to evaluate the performance and safety of a novel high-pressure waterjet-assisted ESD knife in colorectal applications. Six female German Landrace pigs with an average weight of 62 kg (range 60-65 kg) were used in this prospective, randomized, and controlled study. Twenty-four ESDs were performed by three endoscopists: Twelve each with the new Erbe HYBRIDknife® flex T-Type (HK-T) and the Olympus DualKnife® J (DK-J), including six rectal and six colonic ESDs per instrument. The order of performance was randomized regarding anatomic position and instrument. As the primary endpoint, ESD knife performance characteristics were combined and rated on a 5-point Likert scale, with 5 Likert points (LP) representing the best response (5 = very good). The HK-T was rated significantly better than the DK-J (4.7 LP versus 4.4 LP, p = 0.0295), mainly because of HK-T injection ability (5 LP versus 3 LP, p < 0.0001) and hemostasis (5 LP versus 4 LP, p = 0.0452). There was no difference in procedure time (HK-T: 35 min versus DK-J: 34 min, p = 0.8005), resection diameter (3.1 cm versus 2.8 cm, p = 0.3492), injection volume (41 mL versus 46 mL, p = 0.5633), and complication rates. HK-T is as effective as DK-J in colorectal ESD in terms of dissection quality but has better injection and hemostatic properties. The impact of these technical advantages on the ESD treatment of patients with large superficial colorectal lesions remains to be clinically verified.

ArgoCap - feasibility and safety of a novel over-the-scope device to facilitate endoscopic APC treatment

INTRODUCTION

Argon plasma coagulation (APC) is an electrosurgical procedure used, among other indications, for treatment of dysplastic Barrett's mucosa. Homogeneous and safe application can be compromised by varying distances and suboptimal angle of the probe to the tissue. In this study, we present ArgoCap, a novel endoscopic device developed to facilitate endoluminal APC treatment. Objectives of this preclinical study were to assess feasibility and safety and to determine suitable APC settings.

MATERIAL AND METHODS

One-hundred and thirty-two APC treatments of predefined areas using various APC settings were performed ex vivo in the opened porcine esophagus. Depth of thermal injury was assessed histologically. Feasibility of APC treatment in different locations was examined in 20 explanted porcine esophagi and in first in vivo porcine applications.

RESULTS

APC treatment in all quadrants of the esophagus was feasible. Histologically, thermal effects involving the whole thickness of the mucosa were visible with all settings. APC with pulsed mode resulted in deep thermal damage with all power settings. No lesions of the muscular layer occurred using precise (E8, E9) and forced (10 W, 20 W) mode.

CONCLUSIONS

Esophageal APC using ArgoCap is feasible and safe. The device has the potential to improve APC treatment of larger mucosal areas.

The efficient of application of a fine magnetic traction system simplifies colorectal endoscopic submucosal dissection: A porcine study

BACKGROUND

Sometimes it is difficult to maintain good visualization of the submucosal layer during colorectal endoscopic submucosal dissection (ESD). This study aimed to evaluate the feasibility and efficacy of a novel traction method, the fine magnetic traction system (FMTS), in colorectal ESD.

METHODS

ESD was performed 10, 15, or 30 cm from the anus in the colorectums of 10 Bama miniature pigs with or without FMTS. The circumcision and dissection per unit time (cm²/min), en bloc resection, perforation and bleeding rates, size and integrity of the specimen and submucosal injection times were analysed.

RESULTS

A total of 60 ESD procedures were performed with or without FMTS assistance. The en bloc resection rates were 100% at 10 and 15 cm from the anus in both the control group (conventional ESD) and the FMTS group. However, at 30 cm from the anus, these rates were only 10% and 70% (p = 0.006). The resection speeds (control vs. FMTS) at the 10, 15, and 30 cm points were 0.35 ± 0.07 cm²/min vs. 0.39 ± 0.19 cm²/min (p = 0.56), 0.30 ± 0.09 cm²/min vs. 0.38 ± 0.02 cm²/min (p = 0.04), and 0.11 cm²/min vs. 0.26 ± 0.10 cm²/min, respectively.

CONCLUSIONS

The FMTS provides effective counter-traction and efficiently reduces the risks and difficulties of difficult colonic ESD in the porcine model.

Histopathological effects of electrosurgical interventions in an in vivo porcine model of colonic endoscopic mucosal resection

OBJECTIVE

Endoscopic mucosal resection (EMR) in the colon has been widely adopted, but there is limited data on the histopathological effects of the differing electrosurgical currents (ESCs) used. We used an in vivo porcine model to compare the tissue effects of ESCs for snare resection and adjuvant margin ablation techniques.

DESIGN

Standardised EMR was performed by a single endoscopist in 12 pigs. Two intersecting 15 mm snare resections were performed. Resections were randomised 1:1 using either a microprocessor-controlled current (MCC) or low-power coagulating current (LPCC). The lateral margins of each defect were treated with either argon plasma coagulation (APC) or snare tip soft coagulation (STSC). Colons were surgically removed at 72 hours. Two specialist pathologists blinded to the intervention assessed the specimens.

RESULTS

88 defects were analysed (median 7 per pig, median defect size 29×17 mm). For snare ESC effects, 156 tissue sections were assessed. LPCC was comparable to MCC for deep involvement of the colon wall. For margin ablation, 172 tissue sections were assessed. APC was comparable to STSC for deep involvement of the colon wall. Islands of preserved mucosa at the coagulated margin were more likely with APC compared with STSC (16% vs 5%, p=0.010).

CONCLUSION

For snare resection, MCC and LPCC did not produce significantly different tissue effects. The submucosal injectate may protect the underlying tissue, and technique may more strongly dictate the depth and extent of final injury. For margin ablation, APC was less uniform and complete compared with STSC.

Spray coagulation with snare-tip versus argon plasma coagulation: An ex vivo study evaluating tissue effects

Background and study aims  Argon plasma coagulation (APC) is an effective and safe modality for many gastrointestinal conditions requiring hemostasis and/or ablation. However, it can be quite costly. A potentially more cost-effective alternative is snare-tip spray coagulation (SC). This study aimed to determine whether SC would be a safe and effective alternative to APC using an ex-vivo model. Methods  Using two resected porcine stomach, 36 randomized gastric areas were ablated for 2 seconds with either APC at 1.0 L/min 20 W (APC20) and 1.4 L/min 40 W (APC40) or SC with Effect 2 60 W (SC60) and 80 W (SC80) from 3 mm. Extent of tissue injury was then analyzed histopathologically. Results  The mean coagulation depth was 790 ± 159 µm and 825 ± 467 µm for SC60 (n = 9) and SC80 (n = 8), respectively. This was compared to 539 ± 151 µm for APC20 (n = 8) and 779 ± 267 µm for APC40 (n = 9). Mean difference (MD) in coagulation depth between SC60 and APC40 was 12 µm (95 % confidence interval [CI], -191 to 214 µm; P  = 0.91) and was 47 µm (95 %CI, -162 to 255 µm; P  = 0.81) between SC80 and APC40. There was a greater depth of injury with APC40 (MD, 240 µm; 95 %CI, 62 to 418 µm; P  = 0.04) and with SC60 (MD, 252 µm; 95 %CI, 141 to 362 µm; P  = 0.004) when compared to APC20. Mean cross-sectional area of coagulation was 2.39 ± 0.852 mm² for SC60 and 2.54 ± 1.83 mm² for SC80 compared to 1.22 ± 0.569 mm² for APC20 and 1.99 ± 0.769 mm² for APC40. Seventy-eight percent reached the muscularis mucosa (MM) and 11 % the submucosa in the SC60 group compared to 50 % and 38 % in SC80 and 56 % and 11 % in APC40, respectively. Thirty-eight percent of APC20 specimens reached the MM. The muscularis propria was unaffected. Conclusions  This small ex-vivo study suggests that SC60 and SC80 may be safe alternatives to APC40 with comparable coagulation depths and area effects.

Endoscopic mucosal ablation - an alternative treatment for colonic polyps: Three case reports

BACKGROUND

Endoscopic resection of non-invasive lesions is now the standard of care for lesions in the GI tract. However, resection techniques require extensive training, are not available in all endoscopy centers and are prone to complications. Endoscopic mucosal ablation (EMA) is a combination of resection and ablation techniques and it may offer an alternative in the management of such lesions.

CASE SUMMARY

In this case series we report the successful treatment of three flat colonic polyps using the EMA technique. Two lesions were treatment naïve and 1 was a recurrence after an endoscopic mucosal resection. The sizes ranged from 2 to 4 cm. All three polyps were ablated successfully with no immediate or delayed complications. The recurrence rate at 1 year of follow up was 0%.

CONCLUSION

Based on this initial experience, we conclude that EMA is a safe and effective technique for the treatment of non-invasive colonic polyps when endoscopic resection techniques are not available.

Endoscopic submucosal dissection with suturing for the treatment of weight regain after gastric bypass: outcomes and comparison with traditional transoral outlet reduction (with video)

BACKGROUND AND AIMS

Although traditional transoral outlet reduction (TORe) involves argon plasma coagulation (APC) before endoscopic suturing, modified endoscopic submucosal dissection (ESD) has also been used. This study aims to evaluate the safety and efficacy of modified ESD-TORe in comparison with traditional APC-TORe.

METHODS

This was a retrospective study of prospectively collected data from patients who underwent modified ESD-TORe and APC-TORe for weight regain after Roux-en-Y gastric bypass (RYGB). Our outcomes were technical success, adverse events as categorized by the American Society for Gastrointestinal Endoscopy lexicon, and percent total weight loss (TWL) at 6 and 12 months and patients who underwent ESD-TORe were matched 1:3 based on gastrojejunal anastomosis (GJA) and pouch sizes to those who underwent APC-TORe. TWL between groups was compared. A linear regression was performed to control for any confounders.

RESULTS

Nineteen RYGB patients underwent ESD-TORe. Technical success rate was 100%, with no severe adverse events. At 6 and 12 months, patients experienced 13.4% ± 6.6% and 12.1% ± 9.3% TWL, respectively (P < .05 for both). Nineteen ESD-TORe patients were also matched with 57 APC-TORe patients based on GJA and pouch sizes. At 12 months, the ESD-TORe group experienced greater weight loss compared with the APC-TORe group (12.1% ± 9.3% vs 7.5% ± 3.3% TWL, respectively; P = .036). On regression analysis, ESD remained a significant predictor of percent of TWL at 12 months after controlling for age, sex, body mass index, weight regain, and years from RYGB (β = 5.99, P = .02).

CONCLUSIONS

Combining endoscopic tissue dissection with suturing provides greater and more durable weight loss for patients with weight regain after RYGB.

Dose response for argon plasma coagulation in the treatment of weight regain after Roux-en-Y gastric bypass

BACKGROUND AND AIMS

Argon plasma coagulation (APC) of gastrojejunal anastomosis (GJA) is effective in treating weight regain after Roux-en-Y gastric bypass (RYGB). This study aims to compare the efficacy of different APC settings for treating weight regain.

METHODS

This was a single-center retrospective study of patients who had undergone RYGB and then underwent APC from 2014 to 2018 for weight regain. Patients receiving only low-dose APC (45-55 W) or high-dose APC (70-80 W) were compared. The primary outcome was the difference in percentage total weight loss (% TWL) between the groups at 6 and 12 months after the last treatment. Secondary outcomes were technical success, adverse events (AEs), and predictors of weight loss at 12 months.

RESULTS

Two hundred seventeen patients met the inclusion criteria and underwent 411 APC sessions. Of these, 116 (53.5%) patients underwent 267 low-dose APC sessions (2.4 ± 1.5 sessions/patient) and 101 (46.5%) patients underwent 144 high-dose APC sessions (1.4 ± 0.7 sessions/patient). Follow-up rates were 82.9% and 75.3% at 6 and 12 months. At 6 months, the low- and high-dose groups experienced 7.3% ± 6.6% and 8.1% ± 7.4% TWL, respectively (P = .41). At 12 months, the low- and high-dose groups experienced 5.1% ± 8.5% and 9.7% ± 10.0% TWL, respectively (P = .008). Technical success was 100%. The overall AE rate was 8.0%; the most common AE was GJA stenosis (4.6%). The GJA stenosis rate was similar for the low- and high-dose groups (3.0% vs 7.6%, P = .06). High-dose APC remained a significant predictor of greater weight loss at 1 year after controlling for confounders.

CONCLUSION

APC is effective at treating weight regain after RYGB, and higher-watt APC was associated with greater weight loss.

Multicenter case series of patients with small-bowel angiodysplasias treated with a small-bowel radiofrequency ablation catheter

Background and Aims

GI angiodysplasia is the most common cause of small-bowel bleeding. Argon plasma coagulation (APC) is preferred for ablation because of its availability, ease of use, and perceived safety, but it has limitations. An instrument capable of repeated use through the enteroscope, which covers more area of intestinal mucosa per treatment with low risk of damage to healthy mucosa, and which improves ablation, is desirable. A series of patients treated with a through-the-scope radiofrequency ablation (RFA) catheter is reported.

Methods

Patients with a previous diagnosis of small-bowel angiodysplasia (SBA) and ongoing bleeding with melena, hematochezia, or iron-deficiency anemia were eligible for treatment. A small-bowel radiofrequency ablation (SBRFA) catheter was passed through the enteroscope instrument channel. The treatment paddle was pushed against the SBA, achieving coaptive coagulation, and the SBA was treated up to 2 times at standard settings of 10 J/cm². The patients' demographics, pretreatment and posttreatment hemoglobin levels, time to recurrence of bleeding, and need for more therapy were recorded. This study was approved by the institutional review boards of the respective institutions.

Results

Twenty consecutive patients were treated from March until October 2018 and followed up until March 2019. There were 6 women (average age 68 years, standard deviation ± 11.1), and 14 men (average age 73 years, standard deviation ± 10.4). All had undergone at least 1 previous EGD and colonoscopy; 14 patients (70%) had SBA on video capsule endoscopy, and 14 patients had undergone previous endoscopic treatment of SBA with APC. A median of 23 treatments were applied (range, 2-99). The median follow-up time was 195 days (range, 30-240 days). Four patients, including 3 with a left ventricular assist device (LVAD), had recurrent bleeding between 45 and 210 days after treatment, and 2 patients received repeated blood transfusions. Three of those patients underwent repeated endoscopies, including a push enteroscopy and an upper endoscopy with no treatment, and a repeated enteroscopy with SBA treated with APC, respectively. One patient with LVAD underwent arterial embolization.

Conclusions

In this case series, bleeding recurred in 20% of patients in a follow-up time of ≤240 days. Notably, 3 of the 4 patients who had recurrent bleeding had an LVAD. These rates compare favorably with reported bleeding recurrence after APC of SBA. More studies on the benefits of SBRFA, which may include reduced risk of recurrent bleeding or prolonging the time to recurrent bleeding, resource utilization, and factors associated with bleeding recurrence are needed.

Effects of argon plasma coagulation on human stomach tissue: An ex vivo study

BACKGROUND AND AIM

Argon plasma coagulation (APC) is a safe alternative treatment for gastrointestinal neoplasms and precancerous lesions. However, the extent of thermal damage after APC is difficult to predict. We investigated the effects of APC on human stomach tissue.

METHODS

Argon plasma coagulation was performed on 10 freshly resected human stomachs that were obtained after total gastrectomy. The effects on tissue were compared across power settings (40, 60, and 80 W), durations (5, 10, 15, 20, and 25 s), and between injection (submucosal injection of normal saline) and control (without injection) groups. Success was defined as complete mucosal necrosis without damaging the muscularis propria.

RESULTS

Without submucosal injection, the incidence of damaging the muscularis propria increased as the power and duration increased. Tissue damage in the injection group was mostly confined to the submucosa, even when using the high-power setting. In the injection group, ablations at 40 W for 20 s, 60 W for 15 s, and 80 W for 15 or 20 s produced success rates ≥80%. In the control group, ablations at 60 W for 10 s, and 80 W for 5, or 10 s produced success rates ≥80%. The optimal energy levels to achieve complete mucosal and submucosal necrosis without damaging the muscularis propria were 800-1600 and 600-800 J in the injection and control groups, respectively.

CONCLUSION

Application of APC produces good results with a low risk of perforation.

Use of endoscopic-assisted argon plasma coagulation for the treatment of colonic vascular ectasia (angiodysplasia) in an adult dog

CASE DESCRIPTION

A 10-year-old neutered male mixed-breed dog was evaluated for a 5-year history of intermittent hematochezia and chronic anemia that were unresponsive to medical treatment.

CLINICAL FINDINGS

Colonoscopy revealed multifocal areas of coalescing tortuous mucosal blood vessels throughout the colon and rectum. Colonic vascular ectasia (angiodysplasia) was diagnosed on the basis of the endoscopic appearance of the lesions.

TREATMENT AND OUTCOME

The dog failed to respond to traditional medical treatments for colonic vascular ectasia and required multiple plasma and blood transfusions. The dog received 4 endoscopic-assisted argon plasma coagulation treatments, which resulted in long-term resolution of gastrointestinal hemorrhage. Colonic perforation occurred during the third argon plasma coagulation treatment. The perforation was surgically repaired. The dog remained free from clinical signs of colonic vascular ectasia for > 1 year after the third argon plasma coagulation treatment and was euthanized because of clinical deterioration associated with progressive heart disease.

CLINICAL RELEVANCE

Endoscopic-assisted argon plasma coagulation treatment is a novel treatment for dogs with colonic vascular ectasia and provided long-term resolution of clinical signs for the dog of this report. In human patients, complications associated with endoscopic-assisted argon plasma coagulation treatment include colonic perforation, which also occurred in the dog of this report.

Argon gas: a potential neuroprotectant and promising medical therapy

Argon is a noble gas element that has demonstrated narcotic and protective abilities that may prove useful in the medical field. The earliest records of argon gas have exposed its ability to exhibit narcotic symptoms at hyperbaric pressures greater than 10 atmospheres with more recent evidence seeking to display argon as a potential neuroprotective agent. The high availability and low cost of argon provide a distinct advantage over using similarly acting treatments such as xenon gas. Argon gas treatments in models of brain injury such as in vitro Oxygen-Glucose-Deprivation (OGD) and Traumatic Brain Injury (TBI), as well as in vivo Middle Cerebral Artery Occlusion (MCAO) have largely demonstrated positive neuroprotective behavior. On the other hand, some warning has been made to potential negative effects of argon treatments in cases of ischemic brain injury, where increases of damage in the sub-cortical region of the brain have been uncovered. Further support for argon use in the medical field has been demonstrated in its use in combination with tPA, its ability as an organoprotectant, and its surgical applications. This review seeks to summarize the history and development of argon gas use in medical research as mainly a neuroprotective agent, to summarize the mechanisms associated with its biological effects, and to elucidate its future potential.

Review article: gastrointestinal angiodysplasia - pathogenesis, diagnosis and management

BACKGROUND

Angiodysplasia (AD) of the gastrointestinal (GI) tract is an important condition that can cause significant morbidity and -rarely - mortality.

AIM

To provide an up-to-date comprehensive summary of the literature evaluating this disease entity with a particular focus on pathogenesis as well as current and emerging diagnostic and therapeutic modalities. Recommendations for treatment will be made on the basis of the current available evidence and consensus opinion of the authors.

METHODS

A systematic literature search was performed. The search strategy used the keywords 'angiodysplasia' or 'arteriovenous malformation' or 'angioectasia' or 'vascular ectasia' or 'vascular lesions' or 'vascular abnormalities' or 'vascular malformations' in the title or abstract.

RESULTS

Most AD lesions (54-81.9%) are detected in the caecum and ascending colon. They may develop secondary to chronic low-grade intermittent obstruction of submucosal veins coupled with increased vascular endothelial growth factor-dependent proliferation. Endotherapy with argon plasma coagulation resolves bleeding in 85% of patients with colonic AD. In patients who fail (or are not suitable for) other interventions, treatment with thalidomide or octreotide can lead to a clinically meaningful response in 71.4% and 77% of patients respectively.

CONCLUSIONS

Angiodysplasia is a rare, but important, cause of both overt and occult GI bleeding especially in the older patients. Advances in endoscopic imaging and therapeutic techniques have led to improved outcomes in these patients. The choice of treatment should be decided on a patient-by-patient basis. Further research is required to better understand the pathogenesis and identify potential therapeutic targets.

Band ligation of gastric antral vascular ectasia is a safe and effective endoscopic treatment

BACKGROUND AND AIM

Gastric antral vascular ectasia (GAVE) or 'watermelon stomach' is a rare and often misdiagnosed cause of occult upper gastrointestinal bleeding. Treatment includes conservative measures such as transfusion and endoscopic therapy. A recent report suggests that endoscopic band ligation (EBL) offers an effective alternative treatment. The aim of the present study is to demonstrate our experiences with this novel technique, and to compare argon plasma coagulation (APC) with EBL in terms of safety and efficacy.

METHODS

A retrospective analysis of all endoscopies with a diagnosis of GAVE was carried out between 2004 and 2010. Case records were examined for information pertaining to the number of procedures carried out, mean blood transfusions, mean hemoglobin, and complications.

RESULTS

A total of 23 cases of GAVE were treated. The mean age was 73.9 (55-89) years. Female to male ratio was 17:6 and mean follow up was 26 months. Eight patients were treated with EBL with a mean number of treatments of 2.5 (1-5). This resulted in a statistically significant improvement in the endoscopic appearance and a trend towards fewer transfusions. Of the eight patients treated with EBL, six (75%) patients had previously failed APC treatment despite having a mean of 4.7 sessions. Band ligation was not associated with any short- or medium-term complications. The 15 patients who had APC alone had a mean of four (1-11) treatments. Only seven (46.7%) of these patients had any endoscopic improvement with a mean of four sessions.

CONCLUSIONS

EBL represents a safe and effective treatment for GAVE.

New bipolar tissue ligator combines constant tissue compression and temperature guidance: histologic study and implications for treatment of hemorrhoids

Background

Several minimally invasive technologies are available to treat common soft tissue lesions including symptomatic hemorrhoids. The use of energy to deliver heat and coagulate target lesions is commonly practiced. This study compares the histologic effects produced on intestinal tissues by two energy-based systems which employ different approaches of heat delivery.

Methods

Two heat delivery systems were evaluated in vivo in a single porcine subject: infrared coagulator and bipolar tissue ligator utilizing constant tissue compression and temperature guidance. Eighteen treatment sites divided into three groups of six were assessed. Treatment site temperature was measured and the effects of thermal treatment in the mucosa, submucosa, submucosal vessels, and muscularis layer were scored. Lateral thermal spread beyond the energy application site was also assessed.

Results

Treatment site temperatures were much lower in the bipolar ligator group than in the infrared coagulator group. The mucosal and submucosal tissue changes observed in tissues treated with infrared energy and bipolar energy at 55°C were similar. Both the mucosal and submucosal tissue changes with bipolar energy at 50°C were significantly less.

Conclusion

Both devices achieved similar histologic results. However, the unique design of the bipolar ligator, which allows consistent capture, constant compression, and temperature monitoring of target tissue, accomplished the desired histologic changes with less muscular damage at much lower temperatures than the infrared coagulator. The use of bipolar ligation could offer clinical advantages such as reduced patient pain and a minimized chance of heat-related collateral tissue damage.

Endoscopic mucosal ablation: a new argon plasma coagulation/injection technique to assist complete resection of recurrent, fibrotic colon polyps (with video)

BACKGROUND

Incomplete piecemeal EMR of large, sessile/flat colon polyps results in polyp recurrence, with massive submucosal scarring making subsequent attempts at endoscopic resection problematic.

OBJECTIVE

We report our experience with a new endoscopic mucosal ablation (EMA) technique that can be used to complement the eradication of recurrent fibrotic colon polyps.

DESIGN

Single-center, retrospective case series.

SETTING

Tertiary-care referral academic endoscopy unit.

PATIENTS

This study involved consecutive patients referred for endoscopic excision of recurrent benign colon polyps with severe submucosal fibrosis (>30% of the entire lesion).

INTERVENTION

Application of high-power argon plasma coagulation (APC), preceded by injection of a submucosal fluid cushion (normal saline/diluted adrenaline and/or sodium hyaluronate solution) to protect the muscle layer, was performed to augment further piecemeal EMR and polyp eradication.

MAIN OUTCOME MEASUREMENTS

Technical safety and success, complication and recurrence rates.

RESULTS

Fourteen patients (mean age 73 years; 9 men, 5 women) with 15 recurrent colon adenomas (mean polyp size 30 mm, 9 proximal/6 distal) were included. EMA with a mean APC power setting of 55 W was applied. Complete polyp eradication was achieved in 9 of 11 patients (82%) at first or second completed follow-up. One patient needed laparoscopic colectomy because of cancer, and 1 underwent transanal endoscopic microsurgery for benign massive recurrence. The other 3 patients with small, easily treatable recurrence (≤3 mm) were followed by 1-year-surveillance. No perforations and no postpolypectomy syndrome were reported.

LIMITATIONS

Single-center, nonrandomized case series with short duration follow-up.

CONCLUSION

EMA appears to be a safe and easily applicable technique to assist the complete eradication of recurrent fibrotic colon polyps.

Investigation of the thermal tissue effects of the argon plasma coagulation modes "pulsed" and "precise" on the porcine esophagus, ex vivo and in vivo

BACKGROUND

Argon plasma coagulation (APC) is a monopolar, noncontact, thermal procedure that is widely used in therapeutic endoscopy. Systematic investigations of the tissue damage ex vivo and in vivo with the new, second-generation APC modes are lacking.

OBJECTIVE

The aim of this study is to compare the tissue effects of the pulsed effect 2 and precise APC modes.

DESIGN AND SETTING

Ex vivo and in vivo animal model.

SUBJECTS

This study involved 3 explanted porcine esophagi and 8 pigs under general anesthesia.

INTERVENTION

APC application on 3 explanted esophagi and during esophagoscopy.

MAIN OUTCOME MEASUREMENTS

The tissue effect was subjected to histological and statistical investigation.

RESULTS

In vivo, a well known type of superficial tissue damage (type A) of the tunica mucosa and a new injury pattern (type B) limited to the tunica muscularis, were found. Ex vivo, only type A injuries were seen. Thermal injury of the tunica muscularis was significantly lower with precise APC compared with pulsed APC in vivo. The pulsed effect 2 shows a positive correlation between the penetration depth and the power (r = 0.38, P < .0002) or application time for the highest power setting used (40 W, r = 0.77, P < .0001). This correlation could not be detected with precise APC because of its very superficial tissue effect.

LIMITATIONS

This was an animal study. The distance of the APC probe to the esophagus may have varied between applications in vivo.

CONCLUSION

Thermal damage by APC of the esophageal tunica muscularis seems to be underestimated ex vivo. The extent of tissue injury was significantly lower with precise APC than with pulsed APC, indicating that precise APC may be suitable for the treatment of particularly thermosensitive, thin-wall anatomy.

Mucosal injury caused by argon plasma coagulation in rabbits

AIM: To investigate mucosal injury induced by argon plasma coagulation (APC) in rabbits.

METHODS: The mucosal injury of large intestine of rabbits was induced by APC with argon gas flow 2.0, 2.5, 3.0 and 4.0 L/min in two pulsed modes. Thickness of mucosa was measured by endoscopic ultra sound (EUS). Qualitative histologic analysis of each site of APC application was performed by light microscopy.

RESULTS: EUS showed high echo in mucosa while low echo in submucosa and muscularis propria. Depth of injury was significantly correlated with argon gas flow (P = 0.006), power setting (P = 0.023) and duration of pulse (P = 0.030).

CONCLUSION: APC is a safe method in treatment of colon disease. The lower argon gas flow and short durations have the lowest risk of deep tissue injury.

Submucosal Injection of Normal Saline can Prevent Unexpected Deep Thermal Injury of Argon Plasma Coagulation in the in vivo Porcine Stomach

BACKGROUND/AIMS

There have been several reports of thermal injury induced by argon plasma coagulation (APC) in animal models, but no follow-up studies have revealed the actual thermal injury.

METHODS

APC was performed on the stomachs of two living minipigs with and without prior submucosal injection of normal saline. The power and argon gas flow were set to 60 watts and 2 L/min, respectively, and pulse durations of 5, 10, and 20 seconds were used. One of the minipigs was killed immediately thereafter and the other was killed 1 week later.

RESULTS

The minipig killed immediately showed only subtle differences between noninjected and injected injuries under all the conditions, and the usefulness of prior submucosal injection was not obvious. However, the minipig killed 1 week later had a deep ulcer extending to the deeper muscle layer at the noninjected site where APC had been applied for 20 seconds, whereas tissue injury of the injected site was limited to the submucosal layer.

CONCLUSIONS

Unexpected tissue damage can occur even using a short-duration APC. Prior submucosal injection for APC might be a safer alternative technique, especially in a thinner and narrower gut wall.

Argon plasma coagulation therapy

PURPOSE OF REVIEW

To give a summary of recent advances in argon plasma coagulation (APC) therapy in gastroenterology.

RECENT FINDINGS

APC has gained importance in gastrointestinal endoscopy during the last decade, and APC technology has improved over time. Recently published studies, mainly consisting of case series, have shown that APC can be used effectively in various forms of gastrointestinal disorders. The complication rates observed during clinical application are low.

SUMMARY

APC can be considered as a well tolerated and effective treatment approach in endoscopy. Further clinical trials including a comparison of APC to other treatment modalities as well as long-term follow-up after APC treatment are required to clarify the relative value of APC in gastroenterology.

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.