Argon plasma coagulation (APC) is a non-contact thermal method of hemostasis that has generated much attention and excitement in recent years. It was introduced as an alternative to contact thermal coagulation (heater probe and bipolar cautery) and to existing non-contact technologies (primarily laser). The theoretical advantages of APC include its ease of application, speedy treatment of multiple lesions in the case of angiodysplasias or wide areas (the base of resected polyps or tumor bleeding), safety due to reduced depth of penetration, and lower cost compared to laser.
Contrary to a common misconception, argon plasma coagulation (APC) is not a laser. This technology uses argon gas to deliver plasma of evenly distributed thermal energy to a field of tissue adjacent to the probe. A high voltage spark is delivered at the tip of the probe that ionizes the argon gas as it is sprayed from the probe tip in the direction of the target tissue. Argon gas is non-flammable and inexpensive to refill. It is easily ionized by the 6000 volt peak energy delivered by the tungsten wire that terminates just proximal to the probe tip. This ionized gas or plasma then seeks a ground in the nearest tissue, delivering the thermal energy with a depth of penetration of roughly 2 to 3 mm. The plasma coagulates both linearly and tangentially. By delivering energy to all tissue near the probe tip, APC can be used to treat a lesion around a fold and not clearly in view or a lesion that cannot be positioned directly in front of the endoscope.
Indications include: Interventional and Therapeutic Gastrointestinal Endoscopy
1. Bleeding vascular ectasia (radiation proctitis, gastric antral vascular ectasia) and angiodysplasia.
2. Hemostasis in tumoral bleeding.
3. Hemostasis in bleeding peptic ulcers and Dieulafoys lesion.
4. Residual tissue destruction at the edge of a polypectomy.
5. Ablation of lesions with difficult endoscopic or surgical resections (Ampullary adenomas, large flat polyps).
6. Treatment of obstructions resulting from tumor growth, specifically when growth enters a stent in the gastrointestinal tract (Devitalization of growing tissue)
7. Devitalization of tumoral tissues in areas with risk of perforation.
Tumor ablation (debulking), Extensive malign stenoses
8. Barrets Esophagus
9. Polypectomy of small and multiple polyps.
10. Osler-Weber-Rendú Syndrome
11. Stent ingrowth and overgrowth
12. Zenker's diverticulum
In addition to open surgical procedures, in the past few years various endoscopic procedures, including the use of APC, have come into use for the treatment of Zenker's
diverticulum. Compared to other methods (laser, electrocautery using forceps or a needleknife) APC offers the advantage of a better hemostasis. The attachment of a cap to the tip of the endoscope as well as the placing of a stomach tube can help
to improve visualization of the anatomical situation An average of 2-- 3 sessions is usually required.
Radiation proctitis can take the form of teleangiectasias and hemorrhagic mucosal changes in the area of the rectum The use of APC to treat radiation proctitis is already
established; it can lead to an improvement of symptoms and bleeding episodes after an average of sessions carried out at an interval of 3 -- 4 week.
Thermoablative procedures for the removal of precancerous Barrett's esophagus. APC does have a role to play in the removal of nonneoplastic, residual Barrett's mucosa after endoscopic removal of an early carcinoma to prevent formation of malignant secondary lesions. APC can also be used in such lesions for ablation of tumors which cannot be removed by repeat endoscopic resection, and for the ablation of small tumor residues along the resection margins after endoscopic resection.
The preferred form of tissue ablation of large tumor masses (debulking) using APC is by means of vaporization using very high energy outputs. In addition to the tumor masses which are directly excised, in the days following the intervention
thermally necrotized tissue will also die off and there will be tissue shrinkage created by the desiccation of the tissue, so that the neoplastic tissue will be further reduced.
In certain cases it may be helpful to perform APC in combination with other endoscopic procedures (for example, bougienage) in order to ensure the free passage of nourish
ment (e.g. in the esophagus).
Bleeding after biopsies
Depending on the choice of biopsy instrument, the removal of biopsy specimens can result in the occurrence of bleeding, and APC can be used for hemostasis.