An in-depth study on the movement and location of the gastro-oesophageal junction

Lee, Yeong Yeh (2013) An in-depth study on the movement and location of the gastro-oesophageal junction. PhD thesis, University of Glasgow.

Abstract

Understanding the physiology of gastro-oesophageal junction (GOJ) is important as failure of its function is associated with reflux disease, hiatus hernia and cancer. It has been suggested that the increased intra-abdominal pressure produced by central obesity may increase acid reflux during transient lower oesophageal sphincter relaxations (TLOSRs) and also predispose to short segment reflux.
In recent years, we have seen impressive developments in high resolution technologies allowing measurement of luminal pressure, pH and impedance. One obvious deficiency is our lack of technique to monitor the movement and location of the GOJ over a prolonged period of time. Both in-vitro and in-vivo studies indicated that it was possible to monitor the position of the GOJ by means of clipping a magnet to the squamo-columnar junction and which was detected by a novel linear probe consisting of a series of Hall Effect sensors. The accuracy for detection of position of the GOJ with this new technique was superior to 10 mm and was as good as fluoroscopy in the detection of position with a correlation co-efficient of 0.96. Without the risk of radiation associated with fluoroscopy, the new probe could be applied over a much longer period than had been previously possible.
Three factors were identified from in-vitro studies which could limit accuracy of the Hall Effect-based probe. These factors were firstly, poor magnet orientation and distance, secondly, the effect of temperature, and thirdly the presence of other ferromagnetic materials. Newer probe having 3-dimensional capabilities is in development. The temperature effect could be reduced by calibrating the probe within a water bath heated to body temperature prior to insertion. Using alongside a 2.7 mm manometer, the ferromagnetic effect could be reduced.
While oesophageal shortening during TLOSRs is due to longitudinal muscle contraction but relatively little is known about the behaviour of the GOJ during its restitution. The return movement of the GOJ is particularly important as failure of this process will produce a persisting hiatus hernia. Detailed examination on migration of the GOJ during TLOSRs and swallows had been performed in 12 healthy subjects. Proximal displacement of the GOJ was present transiently during TLOSRs and swallows but the displacement of up to 9 cm (median 4.3 cm) during TLOSRs represented very severe herniation of the GOJ. In addition, there was a rapid initial return of the GOJ following TLOSRs when the CD was relaxed and its correlation with amplitude suggested it is due to elastic recoil of the POL. This marked stretching of the POL during TLOSRs may contribute to its weakening and development of established hiatus hernia.
Epidemiological evidence suggests an association between obesity, reflux disease and hiatus hernia but mechanisms are unclear. Study was performed to assess the structure and function of the GOJ in asymptomatic subjects with and without obesity and the effects of elevating intra-abdominal pressure with waist belt. Sixteen subjects were recruited to achieve two groups defined by normal (eight) or increased (eight) waist circumference, matched for age and gender. Our studies demonstrated that increased WC and waist belt caused marked changes in the functioning of the GOJ and LOS leading to increased gastric acid penetration within the high pressure zone. This appears to occur by retrograde flow within the closed sphincter and by increased short segment reflux during TLOSRs and subsequent impaired clearance. This increased intra-sphincteric acid exposure is occurring in asymptomatic volunteers and may explain the high incidence of inflammation and columnar metaplasia observed at the GOJ in asymptomatic subjects. Our observations may also be relevant to the aetiology of adenocarcinoma of the cardia which shares epidemiological risk factors of the oesophageal adenocarcinoma but has a much weaker association with reflux symptoms.
To conclude, a new technique has been developed allowing accurate and prolonged detection of position and movement of the GOJ without any radiation risk. Using alongside high resolution manometry and pHmetry, the new technique allows detailed examination of the structure and function of the GOJ providing important insights on the pathophysiology of reflux disease in normal subjects with and without central obesity and waist belt.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: oesophageal shortening, gastro-oesophageal junction, gastro-oesophageal reflux disease, Hall Effect, hiatus hernia, intra-abdominal pressure, intrasphincteric acid reflux, magnet, obesity, squamo-columnar junction, transient lower oesophageal sphincter relaxations, waist belt
• Subjects: R Medicine > RC Internal medicine; R Medicine > RZ Other systems of medicine; T Technology > TK Electrical engineering. Electronics Nuclear engineering
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Supervisor's Name: McColl, Prof. Kenneth E.L.
• Date of Award: 2013
• Depositing User: Dr Yeong Yeh Lee
• Unique ID: glathesis:2013-4434
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 02 Jul 2013 08:59
• Last Modified: 02 Jul 2013 08:59
• URI: https://theses.gla.ac.uk/id/eprint/4434