The great beyond: radiofrequency ablation for hemostasis
30 October 2014 (online)
There’s a new planet in the solar system, there is nothing up my sleeve … I’m pushing an elephant up the stairs … I’m breaking through, I’m bending spoons, I’m keeping flowers in full bloom, I’m looking for answers from the great beyond … [*]
Radiofrequency energy has been used in the field of medicine for more than 75 years, and new applications are continually emerging . Radiofrequency ablation (RFA) is a medical procedure in which precancerous or dysfunctional tissue is ablated using the heat generated from high-frequency alternating current (in the range of 350 – 500 kHz). This is accomplished using a special balloon (HALO-360), several focal devices (HALO 90, 20 mm length × 13 mm width; HALO 60, 15 mm × 10 mm; and the Ultra, 40 mm × 13 mm; Covidien GI Solutions, Sunnyvale, California, USA), which are mounted on the endoscope, or a through-the-scope channel device (15.7 mm × 7 mm) for direct application onto the target mucosa . Tight electrode spacing (< 250 μm) leads to more superficial tissue injury, and this allows ablation of the epithelium and muscularis mucosa without injuring the submucosa. The geometry of the bipolar electrode array helps to precisely control the depth of ablation to < 1000 μm. If the submucosa is not injured, there is less risk of bleeding, fibrosis, and stricture formation.
Extensive clinical use has established the role of RFA in the treatment of patients with dysplastic Barrett’s esophagus in a safe and cost-effective fashion. New studies, including two in this issue of Endoscopy  , are opening the way for a new application of RFA, that is, hemostasis of vascular abnormalities of the gastrointestinal tract.
Gastric antral vascular ectasia (GAVE), or watermelon stomach, is a rare but important cause of occult or overt gastrointestinal bleeding and anemia . GAVE was first reported in 1953 in an elderly woman with chronic iron deficiency anemia, and reflects underlying erosive atrophic gastritis with marked venocapillary ectasia . GAVE is now a well-defined, acquired gastric vasculopathy seen mostly in patients with cirrhosis, chronic renal insufficiency, and progressive systemic sclerosis; however, its pathophysiology is still unclear. Endoscopic ablation of GAVE using argon plasma coagulation (APC) or band ligation have been used, mostly with success. However, treatment-refractory cases occur, and many patients continue to bleed or remain transfusion dependent. Several, uncontrolled case series using the focal HALO technique have recently shown substantial promise in such cases .
Chronic radiation proctitis (CRP) occurs in 5 % – 20 % of patients following pelvic radiotherapy, typically for carcinoma of the prostate, rectum, urinary bladder, cervix, uterus, and testes . Histologically, radiation-induced mucosal damage results in endothelial dysfunction, microvascular injury with intimal fibrosis, and arteriolar thrombosis leading to ischemia, fibrosis, and formation of neovascular lesions. Although CRP may resolve spontaneously, it may be associated with diarrhea, tenesmus, fecal urgency, recurrent rectal bleeding, and/or iron deficiency anemia requiring blood transfusions. With the exception of hyperbaric oxygen therapy, medical therapies for CRP have been largely unsatisfactory . Endoscopic therapy using heater probe, bipolar electrocoagulation, APC, Nd:YAG or KTP laser, have been associated with significant complications and refractory bleeding. In particular, the depths of tissue damage with these modalities are 2 – 3 mm from the surface on single application and can be deeper after multiple applications, leading to ulcerations, strictures, and fistulas. Newer, more promising methods of endoscopic ablation, such as RFA, may provide a safer, more efficacious, and better-tolerated choice.
The excellent tolerability and low rate of adverse events seen with RFA in either GAVE or CRP  , have been described by others   . Desirable outcomes include bleeding cessation, symptom relief, discontinuation of transfusions and iron therapy, improvement in telangiectasia scores, or normalization of mucosal appearance. From the technical perspective, GAVE is best approached in a forward-viewing position, with the endoscope deflected to place the articulated electrode pad mounted at the 6 o’clock position against the mucosa to be treated, an energy density of 12 – 15 J/cm2 and a power of 40 W/cm2, and with ablation starting from the pylorus and moving proximally. The endoscope is then removed as needed to readjust the position of the electrode to the 10 o’clock and 2 o’clock positions in order to allow circumferential ablation of all visible lesions. Without scraping the coagulum, the pad is moved to completely ablate the pathological gastric mucosa. It is best to treat CRP using a retroflexed gastroscope and the HALO device (similar settings) mounted in the 6 o’clock position to allow best visualization and RFA application, and to avoid more than two ablations per site or overlapping treatments. It is important not to re-treat oozing sites during a given session and instead to delay re-treatment for 3 – 4 months. Full bowel preparation is suggested to minimize unlikely ignition of bowel gas  . The choice of focal HALO electrode size is currently at the discretion of the endoscopist, based on the extent of the disease to be treated.
In the absence of controlled clinical trials that properly assess the tolerability, safety, efficacy, and durability of RFA, and faced with the challenges of refractory GAVE or CRP, the gastroenterologist needs to decide on how to best manage these patients, and the two studies in this issue of Endoscopy provide useful insights but not complete answers. Overall, these two retrospective, multicenter case series, matching other recent studies   , highlight RFA as a promising modality in refractory cases of GAVE and CRP, and educate the clinician on why, if, when, and how to use this option for their patients. The studies also report the expectations, limitations, risks, and uncertainties of RFA use in these settings. We still do not know whether RFA is equal, better, or worse than other endoscopic options, such as APC or banding. However, given the relative scarcity of these vasculopathies in any given individual clinical practice, the likelihood of data from controlled, comparative trials becoming available appears low. Endoscopists are therefore urged to do the following: carefully diagnose, assess, and quantify the impact of such lesions on their patients; decide on the need for endoscopic therapy; balance the benefits and risks of intervention; carefully consider the technical aspects of RFA; and continually reassess their patients for tolerability, efficacy, and durability of effect.
The “great beyond” is supposed to reflect the “farther side of,” the “more distant than,” the “outside the understanding and the limits of,” the “superior to,” or the “over and above all others,” and the R.E.M. song lyrics quoted above were included to symbolize such a difficult, but not impossible, task. The data to date on RFA for hemostasis of GAVE and CRP need to be seen in perspective, analyzed carefully, and applied selectively, but they are poised to be that “great beyond” …
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