Assessing the conditions for in vivo electrical virtual biopsies in Barrett's oesophagus.

It has previously been shown that it is possible to differentiate between squamous and columnar epithelia in rat and resected human tissues using an impedance probe to make in vitro measurements. This probe can be passed down an endoscope allowing measurements to be made in patients. However, the probe emerges parallel to the oesophageal wall, with little room to manoeuvre. The conditions of control required to give reliable readings have been investigated. The importance of pressure applied and the angle of approach to the oesophagus was assessed. Pressures in the range 26.6 Pa to 46.3 kPa and angles in the range 15-90 degrees were considered. In in vitro studies it was observed that it was possible to obtain consistent readings with pressures greater than 2.9 kPa and with angles greater than 15 degrees between the probe and the oesophagus. These conditions can be achieved in vivo, and readings obtained from twelve patients are shown (45 readings on normal squamous, 34 on Barrett's oesophagus and 22 on stomach). At low frequencies (9.6-153.2 kHz), a Mann-Whitney test shows a significant difference (p < 0.001) when comparing the means from squamous and columnar, and also when readings from Barrett's and normal gastric epithelia are compared (p < 0.001).

Virtual biopsies in Barrett's esophagus using an impedance probe.

Preliminary results of electrical impedance measurements in squamous and columnar epithelia in rat and human tissues are presented. The aim of this work is to show the possibility of differentiating these two types of epithelia in terms of their electrical characteristics. For the measurements, we employed a 1.95-m-long, 3.2-mm-diameter, four-electrode probe designed to be used transendoscopically in the diagnosis of Barrett's esophagus (BE). BE is a condition in which the normal squamous epithelium of the esophagus is replaced by columnar epithelium of the intestinal type. This metaplasia is considered as a premalignant condition that puts patients at a 30-125-fold risk of developing adenocarcinoma of the esophagus. The diagnosis and surveillance of BE involve taking multiple biopsies, an expensive and time-consuming procedure. This study constitutes the first stage in the replacement of tissue biopsy by "virtual biopsies".

H2-antagonists in the treatment of recurrent ulceration after vagotomy.

Twenty-two patients with recurrent ulceration following vagotomy with and without a drainage procedure have been treated with histamine H2-antagonists and followed for up to 3 years. Four of a group of 6 patients responded to a single therapeutic course. Ten of 16 patients assigned to long term maintenance treatment remain symptom-free. Cimetidine may be an alternative to further surgery in the treatment of some patients with recurrent ulceration after vagotomy.