Kelly, Keith A.

The hypothesis was that orally moving pacesetter potentials distal to a site of jejunal transection and anastomosis would slow transit through jejunum containing them and that reoperation with excision of bowel containing these pacesetter potentials would restore transit to the control. In six conscious dogs with jejunal serosal electrodes for recording myoelectric activity and a jejunal perfusion/aspiration catheter for measuring transit, jejunal pacesetter potential frequency decreased distal to a midjejunal transection and anastomosis from 18.7 +/- 0.3 (SE) cycles/min (cpm) proximal to the site to 14.4 +/- 0.6 cpm distal to the site (P < 0.05). In addition, orally propagating pacesetter potentials occurred > 25% of the time in a 37 +/- 7 cm length of bowel distal to the site during fasting and after feeding. Transit through the segment with the orally moving pacesetter potentials was slowed during feeding (half time before and after transection, 7.7 +/- 1.1 and 13 +/- 2.0 min, respectively, P < 0.05). Resection of the segment with the abnormal pacesetter potentials shortened the length of bowel containing them to 24 +/- 2 cm (P > 0.05) and restored transit to the control. In conclusion, orally moving pacesetter potentials distal to a canine jejunal transection and anastomosis slowed transit through the segment of bowel containing them. Resection of the segment restored transit to the control.

The aim of this study was to determine what factors influence the direction of movement of canine jejunal chyme. In four dogs, pacing electrodes were implanted near each end of a 50-cm jejunal Vella loop, while recording electrodes and intraluminal pressure catheters were spaced along the loop. After recovery, the loop was perfused from either the proximal stoma (forward flow) or the distal stoma (reversed flow), and effluent was collected from the nonperfused stoma. The pacesetter potentials were paced electrically in a forward (aborad) or a reverse (orad) direction. During control conditions (forward flow-forward pacing), the mean transit time of liquids was 2.6 +/- 0.1 min (mean +/- SE) and the static volume of the loop was 8.8 +/- 0.3 ml. Reversing both direction of flow and direction of pacesetter potential propagation slowed transit (4.4 +/- 0.4 min; P less than 0.05) and increased loop volume (16.0 +/- 1.0 ml; P less than 0.01). Reversing flow with forward pacing resulted in even slower transit (7.5 +/- 1.2 min; P less than 0.05), maintained a large volume (33 +/- 10 ml), and increased basal pressure in the loop from -1.2 +/- 1.7 (control) to 2.3 +/- 1.6 mmHg (P less than 0.05). These observations suggest that the direction of propagation of jejunal pacesetter potentials influences the direction of movement of jejunal chyme but that other factors have a role as well.

Our hypothesis was that the direction of liquid transit through the canine jejunum is determined by the direction that single jejunal pressure waves spread, while the direction of solid transit depends on the direction of spread of both single waves and clustered waves. In six dogs, 80-cm jejunal Vella loops were made and fitted with manometric catheters and serosal electrodes. After recovery, transit of liquids (Ringer lactate) and solids (2.4-mm nylon spheres) placed into the center of the loop was determined in the conscious animals while pacing the loop in a forward direction or in a backward direction. Under fasting and fed conditions, single pressure waves followed the direction of pacing, while the direction of migration of clustered waves was not determined by the direction of pacing. Liquid transit always followed the direction of single pressure waves. In contrast, solids moved distally regardless of the direction of pacing, except when liquids were also present in the lumen, in which case solids moved in the same direction as the single pressure waves.

Gastric pacing has been achieved in dogs and humans, but its effects on gastric motility and emptying have not been thoroughly explored. Seven dogs had bipolar electrodes placed 1 and 10 cm proximal to the pylorus for reverse and forward pacing and monopolar recording electrodes and strain gauges placed 3, 5, and 7 cm proximal to the pylorus. After recovery, myoelectrical and contractile activity and gastric emptying of a mixed meal (50 g 99mTc-labeled liver and 250 ml 111In-labeled 5% dextrose broth solution) were measured in each of three conditions: no pacing, reverse pacing, and forward pacing (frequency 0.5 cycles/min above intrinsic pacesetter potential frequency). Reverse pacing reversed the direction of > 90% of antral pacesetter potentials and peristaltic waves in six of seven dogs, prolonged the lag phase of solid emptying, prolonged the half emptying time of solids and liquids, and increased the antral motility index. Forward pacing entrained pacesetter potentials but had no consistent effect on emptying or antral contractions. In conclusion, reverse gastric pacing slows gastric emptying of digestible solids and liquids by reversing the direction of antral peristalsis and increasing the antral motility index, whereas forward pacing has no such effects.

Summary In 4 dogs a 75-cm segment of jejunum was isolated from the intestinal stream. Stimulating electrodes were implanted at each end of the segment and recording electrodes at intervals between. The two ends of the segment were fashioned as stomas on the anterior abdominal wall. After recovery, the electrical activity of the segment was continuously recorded, whilst a solution of 100 mmol/l glucose and 90 mmol/l NaCl was infused into the proximal stoma at 2.9 ml/min. Effluent from the distal stoma was collected in 5-min aliquots for three consecutive 30-min periods. In the second period electrical stimuli were given via either the proximal or the distal bipolar electrodes to entrain pacesetter potentials. Both forward and backward electrical pacing decreased the output of water, glucose and sodium from the jejunal segment, but the decrease was significantly greater with backward pacing. We conclude that pacing a segment of jejunum backwards with electrical stimuli produces a greater increase in absorption from the segment than pacing it forwards, a finding which has therapeutic implications in patients with the short bowel syndrome.

Abstract Gastric emptying of solids and liquids was measured in 12 dogs with and without corporal or antral gastrojejunostomy. Both types of stoma hastened the onset but did not alter the time from onset to complete emptying of 40 small plastic spheres. Corporal gastrojejunostomy slowed the emptying of 400 ml. of 154 mM NaCl but not of 500 mM glucose, whereas antral gastrojejunostomy slowed the emptying of both.

AbstractAmong 971 patients with chronic ulcerative colitis who underwent ilealpouch anal anastomosis during an 8‐year period from January, 1982 to December 1989, 30 patients were randomly selected from each year (total = 240 patients) for an assessment of their long‐term functional results and quality of life as of 1990. Patients undergoing cholecystectomy during each of the same years served as “controls” (20 patients/year, total = 160 patients). All 400 patients completed a written questionnaire that measured bowel habits, overall quality of life, general health, and performance in sports/recreation, travel, sex life, family relationship, occupational work, social activities, and household activities. Ileo‐anal patients had more frequent stools (median, 6 stools/day) and more fecal spotting (68% of patients had episodes) than cholecystectomy patients (median, 1 stool/day, 13% had episodes,p<0.05). In spite of the altered bowel habits, 90% of ileo‐anal patients had an excellent overall quality of life, 76% enjoyed good health, and 91% had good performance scores in the areas examined. In fact, quality of life and performance were similar among ileo‐anal patients and cholecystectomy patients. Moreover, quality of life and bowel habits remained steady in both groups of patients during the 8‐year follow‐up. In conclusion, functional results were satisfactory and quality of life was excellent after ileal pouch‐anal anastomosis; neither deteriorated as patients aged over an 8‐year period after operation.

AbstractThe motor function of the ileal J pouch after ileal pouch‐anal anastomosis has a key role in the clinical outcome. The pouch forms a neorectum that aids in the maintenance of reasonable continence. The maximum capacity of the pouch (mean, 320 ml) is similar to that of the healthy rectum (330 ml). The pouch accommodates to distension, keeping intrapouch pressure low as the pouch gradually fills with stool. The change in pouch volume with each change in pressure (15 ml/mm Hg) approximates that of the healthy rectum (19 ml/mm Hg). When a threshold volume of about 150 ml is reached, large‐amplitude (>25 mm Hg), prolonged (40–60 sec), propulsive waves appear in the pouch. They initiate the call to stool. With continuing distention of the pouch to its functional capacity, which is about 200 ml, reflux of stool into the distal ileum begins, the large pressure waves become more frequent, and the urge for defecation more intense. Defecation is voluntary, spontaneous, and rapid (11 ml/sec), with the pouch and distal ileum emptying concurrently. About 60% of the pouch content, a volume of about 100 ml of stool, is discharged with each bowel movement. The greater the threshold volume and the more complete the evacuation, the fewer the bowel movements per day. After evacuation, the large pressure waves subside, and the next cycle of pouch filling and emptying begins.