Chapter 15 (page 71)

The Pyloric Sphincteric Cylinder in Health and Disease

Go to chapter: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39
Chapter 15 (page 71)

Chapter 15

Manometry at the Gastroduodenal Junction

Atkinson et al. (l957) stated that although the pyloric sphincter was a well-defined anatomical structure, there was doubt whether it functioned physiologically as a sphincter in the sense that it closed the stomach off from the duodenum. Using a system of small air-filled balloons and air-filled, open-tipped tubes, these authors investigated intraluminal pressure profiles in the pyloro-duodenal region in normal subjects as well as in patients with active duodenal ulceration and with non-ulcer dyspepsia. Measurements were taken in the fasting stomach and in stomachs containing a mixture of food and barium sulphate. In no instance could a band of increased pressure be obtained anywhere in the region of the duodenal cap, pyloric canal or pyloric "antrum". While phasic pressure waves were recorded in the pyloric region on many occasions, and while it was possible to correlate radiologically visible peristaltic waves inthe corpus and "antrum" with the pressure records, no convincing evidence of independent contractions at the gastroduodenal junction (i.e. the pyloric ring) was found. It was concluded that the diameter of the pyloric ring was more than 7.0 mm most of the time, whether the stomach was empty or not. These authors could not demonstrate a physiological sphincter in the sense of a tonically contracted muscular ring which kept the lumen tightly closed and which relaxed intermittently to allow gastric contents to pass into the duodenum.

The phasic pressure waves recorded on the gastric side of the ring were deemed capable of causing partial or complete obliteration of the lumen. Each contraction was found to be intermittent and brief, and involved a segment 3.0 to 4.0 cm in length. It probably reduced the bore of the pyloric canal and closed it momentarily. (Comment: "Pyloric canal" was equated with the pyloric aperture). Atkinson et al. (l957) concluded that the pylorus was normally relaxed; there was no evidence that it acted antagonistically to peristaltic or other phasic pressure waves.

Andersson and Grossman (l965), using a system of small (5.0 to 10 mm diameter) water- filled balloons, recorded intraluminal pressures of the pyloro-duodenal region in normal, fasting, supine human subjects. As a balloon was withdrawn from the duodenum through the pylorus, a change in pressure occurred only rarely. During 7 of 130 withdrawals, i.e. in approximately 5 percent of instances, a transient pressure peak of variable magnitude occurred when the balloon passed the "sphincter". It was concluded that the pyloric sphincter was usually not detectable by pressure measurements and that these measurements could not be used as a means of identifying the pylorus. The luminal diameter of the resting pylorus in supine subjects appeared to be greater than 10.0 mm.

Brink et al. (l965) measured intraluminal pressures of the gastroduodenal region in canines. Having performed a gastrostomy and duodenostomy in each animal, cannulae were inserted into the stomach and duodenum through which water-filled, open-tipped tubes and small balloons were introduced into the lumen. As the pressure-detecting units were withdrawn, an increase in resting pressure occurred when the gastroduodenal junctional zone was reached. The magnitude of the change in pressure varied with the cross-sectional diameter of the detecting instrument. With the open-tip tube, elevation of pressure occurred in the junctional zone in 15 of 25 tests on 5 dogs. The mean length of the zone of increased pressure varied from 1.1cm to 1.6 cm. With balloons an increase in pressure was detected more often. The frequency with which they were able to demonstrate a high pressure zone rose as the size of the balloon sensor was increased. With a 7.0 mm diameter balloon, a rise in pressure was seen in 97 percent of 58 observations. Instillation of acid into the duodenum caused an increase in the pressure peaks of the junctional zone, with a simultaneous increase in amplitude of duodenal contractions (type I pressure waves) and a cessation of motor activity in the "antrum". It was concluded that there was a narrow zone of raised pressure at the gastroduodenal junction in fasting dogs, in which the diameter of the lumen was less than 7 mm most of the time.

Carlson et al. (l966) investigated motor action of the canine gastroduodenal junction by means of combined cineradiographic, manometric and electrical studies. Small intraluminal water-filled balloons were positioned in the first part of the duodenum and within 3.0 to 4.0 cm of the pyloric ring on the gastric side, i.e. in the "terminal antrum". The balloons were connected to external strain gauge transducers by means of cannulae. When a Type II contraction (Chap. 13) reached a point 3.0 to 4.0 cm from the pyloric ring, the terminal antrum and pyloric canal distal to it contracted simultaneously, or almost simultaneously, in a segmental way; such vigorous terminal antral contractions (TAC) caused sharp elevations in intraluminal pressures. The pyloric canal almost always contracted with the terminal antrum. (Comment: "Pyloric canal" was equated with the pyloric aperture). The mean duration of TAC was 3.1 seconds, the mean time interval between completion of cycles 12.7 seconds, and the mean rate 4.8 per minute.

Isenberg and Csendes (l972), using open-tipped perfused tubes as pressure sensors, measured intraluminal pressures in canines prepared with gastric and duodenal cannulas. The sensors were moved in 1.0 cm increments back and forth across the pylorus. Mean resting pyloric pressure when the sensors were moved from the stomach to duodenum was 14.8 cm H²0; when they were moved from duodenum to stomach, it was 8.9 cm H²0. Intravenous infusion of cholecystokinin octapeptide produced an increase in pyloric pressure. Mean sphincter length was 1.8 cm. It was concluded that the dog pylorus was tonically contracted and that the resting tone was increased by octapeptide of cholecystokinin.