CHARACTERIZATION OF CYCLIC MOTOR PATTERNS AND HAUSTRAL ACTIVITIES IN THE HUMAN COLON BY HIGH-RESOLUTION MANOMETRY

Abstract

This thesis focuses on the characterization of rhythmic activity in the colon of healthy subjects and patients diagnosed with refractory constipation; this activity is mediated by pacemaker cells in the gastrointestinal system, the Interstitial cells of Cajal (ICC). The myogenic activity described are the cyclic motor patterns (CMP) and haustral activity; characterization of these motor patterns in healthy subjects provided control values for the subsequent comparison in patients. Frequency analysis of CMP revealed a novel high-frequency activity (7-15cpm) unrelated to the breathing artefact. Three categories of cyclic motor patterns were observed: (1) CMP following mass peristaltic events (HAPW); (2) those that occur in isolation of other colonic motor patterns (HAPW) in the colon; and (3) low-frequency (2-6cpm), prominently retrograde rhythmic activity in the rectum. CMP were scarcely present in majority of the patients; however, elevated retrograde CMP in the distal colon and rectum in some patients plays a role in retarding flow of colonic content. A detailed characterization of haustral activity (comprised of 2 boundaries and the activity within a haustrum) is reported for the first time using high-resolution colonic manometry. Furthermore, we find that over expression of haustral boundary activity in patients serves as a disproportionate hindrance in colonic transit. An in-depth methodology is developed for the identification and subsequent analysis of haustral activity and CMP; this provides transparency in the data acquisition and analysis. Lastly, a sphincter at the rectosigmoid junction, sphincter of O’Beirne is presented in a patient case report. The persistent presence and paradoxical contractions of this sphincter served to impede flow colonic content, an important factor contributing to the pathophysiology of severe refractory constipation.