The effect of vagotomy and gastrectomy on the lower esophageal sphincter motility

The motor activity of the canine lower esophageal sphincter (LES) was studied under conscious states by means of the strain gage transducer, and gastroesophageal reflux was investigated after injection of the contrast medium through the silastic tube inserted in gastric fundus by x-ray. The motor activity and function of LES were observed in the dogs with selective proximal vagotomy (SPV), truncal vagotomy (TV) and TV + gastrectomy. Results were summarized as follows; 1. In the postprandial period, so called receptive relaxation was observed in gastric body, and tonic contraction was observed in LES. On the other hand, the occurrence of the LES contraction was consistent with gastric periodic motor activity in the interdigestive state. It was found that such a contractile pattern of LES and gastric body prevented the reflux of gastric juice from stomach to esophagus in the digestive and interdigestive state. 2. In the postprandial period, the tonic contraction of LES was inhibited by the venous injection of atropine sulfate. Mechanisms of digestive contractile activity of LES were mainly regulated by cholinergic nerve. 3. After SPV and TV, the motility of LES and gastric body was disturbed. Namely, receptive relaxation disappeared, and tonic contraction was observed in gastric body, but the relaxation of the LES was found after ingestion. These findings suggested that discordant LES contractiles with the contraction of the gastric body after vagotomy produced a gastroesophageal reflux. 4. After TV + gastrectomy, the synchronous motor activity of the LES, remnant stomach and duodenum disappeared. Namely, it was thought that the reflux esophagitis occurred after gastric surgery with vagotomy and lymphnodes dissection was caused by the duodenal juice reflux to remnant stomach and esophagus.     

The Effect of Parietal Cell and Truncal Vagotomy on Gastric and Duodenal Contractile Activity of the Unanesthetized Dog

The antral-duodenal contractile relationship was studied in control, after parietal cell vagotomy and truncal vagotomy conditions using extraluminal strain gage transducers. All conditions were investigated under interdigestive and digestive states and after insulin, bethanechol and histamine. After parietal cell vagotomy, there was minimal alteration of the antral-duodenal relationship in both the interdigestive and digestive states. The number and amplitude of contractions on both the antrum and duodenum (as reflected by a motility index) were not changed from control by the various stimulants. The one exception was that histamine markedly stimulated the duodenal contractile activity. In the truncal vagotomy condition, there was a total disruption of the antral-duodenal relationship in the interdigestive and digestive states. There was a significant decrease in the number and amplitude of contractions occurring on the antrum during the interdigestive and after insulin stimulation. Food was ineffective in stimulating the antrum in 2 of 3 dogs. In contrast, motor activity of the duodenum was minimally influenced by truncal vagotomy. In conclusion, parietal cell vagotomy has minimal disruptive effects on the antralduodenal relationship while truncal vagotomy reduces antral contractile activity.     

The antrum can control gastric emptying of liquid meals.

Electrodes and force strain gauge transducers were implanted in dogs on the anterior gastroduodenal serosa for monitoring of contractile Percentage Activity and Gastric Work patterns and burst peak-to-peak durations, while fasting and after instillation of either isotonic sodium citrate or hypertonic 10% dextrose meals. The dogs were further divided at time of implantation into three surgical models: (i) otherwise intact stomachs or controls (CON), (ii) proximal gastric vagotomy with innervated antrum (PGV), and (iii) truncal vagotomy with posterior pylorectomy (TVP). Gastric emptying of the isotonic meal did not alter the normal interdigestive motility of the gastric antrum in any model. Whether instilled in the midst of or after a normal burst cycle, the hypertonic meal promptly inhibited antral contractions and significantly prolonged the burst peak-to-peak interval in animals with a vagally innervated antrum (CON, PGV). The inhibition lasted until >80% of the meal had emptied, followed by gradual return to normal burst activity. The inhibition ceased promptly when the half-emptied residual meal was aspirated from the stomach. The meal emptied faster, and inhibition was much less apparent in the TVP model. The data document that the vagally innervated gastric antrum (CON, PGV) controls emptying of hypertonic liquids by active inhibition of contractions. Antral denervation (TVP) produces contraction discoordination and impaired inhibition.     

Effects of various types of vagotomy on electrical and contractile activities of the canine stomach (author's transl)

Thirteen mongrel dogs equipped with four bipolar electrodes and three strain gauges on the anterior wall of the stomach underwent three types of vagotomy: truncal vagotomy (TV)-6 dogs; selective proximal vagotomy (SPV)-3 dogs; and antral vagotomy (AV)-4 dogs. Electrical and contractile activities of the stomach were examined before and after these vagotomies on both the fasting and postprandial states. TV caused an increased incidence of dysrhythmia and a 12 to 33% reduction of the propagation velocity of the basic electrical rhythm (BER). Following feeding, the characteristic waxing and waning pattern of normal gastric contraction was altered to a monotonic steady pattern, increasing overall contraction activity of the pyloric sphincter. These changes seem to be attributable to delayed gastric emptying following truncal vagotomy. SPV reduced the propagation velocity of the BER slightly (2.5-7.3%), preserving the inherent physiological contractile activity in the antrum and pyloric sphincter, and transforming the contractile activity in the corpus to a more monotonic pattern. AV effected a localized monotonic contractile activity in the antral region with no changes discernible in the body and pyloric sphincter. The propagation velocity was not changed significantly by antral vagotomy. The discharge interval of the BER was not altered significantly by these vagotomies.     

Effect of vagal denervation on canine gallbladder motility

There is an increased incidence of gallstones after truncal vagotomy but the mechanism is unknown. Our aim was to study the early effects of vagotomy on fasting and postprandial gallbladder motility. A chronic model was constructed in 10 dogs to correlate gallbladder motility and emptying with interdigestive and postprandial duodenal motility both before and after selective hepatobiliary vagotomy (five dogs) and truncal vagotomy (5 dogs). During each study recordings were made for one complete interdigestive motor complex (IDMC) and for 90 min after a standard meal of (a) gallbladder and duodenal motility, (b) gallbladder emptying (by a dual radioisotope marker technique) and (c) duodenal output of bilirubin. In control studies the gallbladder contracted at the start of phase II of the interdigestive motor complex and ejected 20-25 per cent of its contents into the duodenum; after meals the gallbladder contracted within 5 min and emptied almost 80 per cent of its contents within 90 min. After both selective hepatobiliary vagotomy and also truncal vagotomy there was no significant difference in the pattern of contraction or emptying of the gallbladder either during fasting or postprandially. We conclude that gallbladder motility and emptying are entirely normal in the early period after vagal denervation.     

Selective role of vagal and nonvagal innervation in initiation and coordination of gastric and small bowel patterns of interdigestive and postprandial motility

Our previous studies suggested that extrinsic innervation modulates upper gut motility but is not requisite for cyclic interdigestive and postprandial motility of the stomach. However, the specific role of vagal and nonvagal extrinsic innervation in the initiation, coordination, and pattern of gastric motility in dogs after denervation of the entire upper gastrointestinal tract remains unclear. The aim of this study was to determine the role of vagal and nonvagal extrinsic innervation in control of gastric motility patterns. Mongrel dogs were subjected first to extrinsic denervation (in situ neural isolation) of the stomach, small bowel, proximal colon, liver, and pancreas but specifically maintaining vagal innervation to the stomach alone. After fasting and fed motility patterns were measured with indwelling gastric and small bowel manometry catheters, the dogs underwent transtboracic truncal vagotomy (completion of total extrinsic denervation of stomach), and motility studies were repeated. Vagal integrity to the stomach and pancreas was confirmed by means of a modified Hollander test and serum pancreatic polypeptide concentrations after the injection of exogenous insulin, respectively. We found that a cyclic motility pattern (migrating motor complex) persisted during fasting in both the stomach and the small bowel and that the patterns of tbe stomach and the duodenum remained temporally coordinated before and after vagotomy. However, although a cyclic phase III activity persisted in the stomach after vagotomy, the number of contractions and the motility index during phase III were decreased, and the duration between groupings of contractions was increased. No differences were noted in the duration of postprandial inhibition after feeding meals before and after vagotomy. These observations support our hypothesis that the vagal nerves are not necessary for the initiation or temporal coordination of global fasting or postprandial gastroduodenal motility patterns but are involved in modulating the pattern of contractions during gastric phase III. Supported in part by United States Public Health Service grant DK 39337 from the National Institutes of Health (M.G.S.) and by the Mayo Foundation. Presented at the Forty-First Annual Meeting of The Society for Surgery of the Alimentary Tract, San Diego, Calif., May 21–24, 2000 (Poster presentation), and published as an abstract in Gustroenterology 118:Al0S0, 2000.     

Erythromycin induces pyloric relaxation accompanied by a contraction of the gastric body after pylorus-preserving gastrectomy

BACKGROUND: Pylorus-preserving gastrectomy (PPG) is a function-preserving surgery; however, long-term retention of food in the residual stomach is a frequent complication during the early postoperative period. We reported that gastric stasis after PPG was attributable to the delayed recovery of gastric phase III, in which pyloric relaxation accompanied a contraction of the gastric body. The objective of the present study is to determine whether erythromycin can induce phase III with pyloric relaxation after PPG. METHODS: We studied gastrointestinal motility in dogs after PPG by using strain gauge force transducer. After randomized administration of either erythromycin or saline, interdigestive gastropyloroduodenal motility was recorded. RESULTS: Erythromycin induced phase III with pyloric relaxation in the early postoperative period. Pyloric relaxation accompanied a contraction of the gastric body. Compared with the saline group (body: 87.2 +/- 16.7 mmHg x min, antrum: 69.7 +/- 13.7 mmHg x min, pylorus: 91.7 +/- 22.1 mmHg x min), the erythromycin group showed significantly increased gastropyloric motility indexes (body: 506.2 +/- 33.5 mmHg x min, antrum: 430.9 +/- 53.7 mmHg x min, pylorus: 589.5 +/- 59.5 mmHg x min). CONCLUSIONS: Erythromycin can induce phase III, in which pyloric relaxation accompanied a contraction of the gastric body in the early postoperative period after PPG. Erythromycin might be used as a prokinetic agent for the treatment of early gastric stasis after PPG.     

Gastric motor response to sympathetic nerve stimulation

This study evaluated the effect of electrical stimulation of the greater splanchnic nerve on gastric motility in pentobarbital-anesthetized dogs. The majority of stimulations produced contractions of the gastric body, proximal and distal antrum. Relaxation was also noted in the body and antrum with some stimulations. Stimulation of the thoracic sympathetic chain identified the gastric motor response as arising distally to level T-6. The excitatory motor response to stimulation was unaffected by cervical vagosympathectomy, thoracic vagotomy, or adrenalectomy. Administration of phentolamine, propranolol, or hexamethonium and pretreatment with reserpine each failed to affect the contractile or relaxation responses. Following atropine administration, contractions due to splanchnic nerve stimulation were abolished in the gastric antrum and were either reduced or abolished in the gastric body. Tetrodotoxin abolished all components of the gastric motor response. The greater splanchnic nerve contains nonadrenergic pathways for contraction and relaxation of the gastric body and antrum. The pathways to the antrum were entirely cholinergic.     

The importance of an innervated and intact antrum and pylorus in preventing postoperative duodenogastric reflux and gastritis.

This study has investigated the relationship between duodenogastric reflux, gastritis and certain symptoms 6-12 months after three operations for uncomplicated duodenal ulcer. The operations studied were proximal gastric vagotomy (PGV, 20 cases), truncal vagotomy and pyloroplasty (TV+P, 22 cases) and truncal vagotomy and antrectomy (TV+A, 21 cases). Duodenogastric reflux was assessed both by a radiological technique and by measuring the concentration of bilirubin in the gastric aspirate before and after operation. Incidence and severity of postoperative gastritis were determined by endoscopic biopsy. Symptoms were assessed by symptomatic score and Visick grading. There was a significant correlation between duodenal reflux and histological evidence of both severe superficial gastritis and glandular atrophy (P less than 0-01). There was also a close association between the degree of reflux and the presence of severe heartburn, epigastric pain and bile vomiting after operation. The amount of reflux did not differ before operation. There was significantly less reflux following PGV than after either TV+P (P less than 0-025) or TV+A (P less than 0-001). The results indicate that an operation which preserves an innervated and intact antrum and pylorus will protect against postoperative duodenogastric reflux, gastritis and symptoms.     

A gastro-electromyographical study on selective vagotomy and proximal selective vagotomy in the dog (author's transl)]

The gastro-electromyographical changes after vagotomy were studied by means of chronic in-situ experiments on eighteen dogs. Basic electric rhythms (slow spikes) were classified into normo-peristalsis and anti-peristalsis. The periodical rhythm of normo-peristalsis was partly disturbed after selective vagotomy but was more regular after feeding. Normally, rate changes of normo-peristalsis show typical patterns depending on the types of meals. These distinctive features were observed more clearly in S.V. and S.P.V. dogs. The incidence of normo-peristalsis and anti-peristalsis during fasting was high in normal dogs and low in S.V. dogs by night. A high level of anti-peristalsis occurred at the antrum in S.V. dogs. Thus, the numbers of normo-peristaltic waves reaching the antrum were decreased in S.V. dogs. After feeding, anti-peristalsis decreased in S.V. dogs but increased in normal dogs. Anti-peristalsis tended to occur in succession with a short cycle just like extra-systole. The author noted that sometimes anti-peristalsis was propagated towards both the orad and the pylorus simultaneously. In both S.V. and S.P.V. dogs, the denervated corpus seemed to have similar functions. On the other hand, in both the S.P.V. and normal dogs, the antrum seemed to function similarly.     

Pyloric motility after pylorus-preserving gastrectomy with or without the pyloric branch of the vagus nerve

An attempt was made to examine gastropyloric motility after pylorus-preserving gastrectomy (PPG) and to determine the influence of the pyloric branch of the vagus nerve in the dog. Fifteen dogs were divided into three groups of five. PPG with preservation (PPPG) and resection of the pyloric branch of the vagus (RPPG) were performed, and controls were prepared. Interdigestive and digestive gastropyloroduodenal motility was recorded after a 2-week recovery period using strain-gauge force transducers (SG). Radiopaque markers (ROMs) were used to assess gastric emptying. No significant differences were found between PPPG and RPPG in terms of gastropyloroduodenal motility during either the interdigestive or the postprandial state. During phase III of the interdigestive state, pyloric relaxation correlated with contraction of the gastric body after both PPPG and RPPG. During the first month it was accompanied by tonic and phasic pyloric contractions after feeding and delayed gastric emptying in two groups. By the end of the first month these pyloric contractions had diminished, and the rate of gastric emptying was similar to that of the controls. We concluded that it is not necessary to preserve the pyloric branch of the vagus for gastropyloroduodenal motility after PPG. Gastric stasis during the early postoperative period is due to tonic and phasic contractions of the pylorus.     

Experimental study on canine gastric motility following selective proximal vagotomy (author's transl)]

Electromyographical studies were made on the gastric motility of dogs following selective vagotomy (SV) and selective proximal vagotomy (SPV) as the subsequent studies on the changes after truncal vagotomy (TV) after which gastric motility is fairly disturbed, and the influence of pyloroplasty additionally performed to SPV. Gastric discharge frequency was suppressed by SV similar to that by TV. Dysrhythmia of motility occurred after gastric vogotomy. Restoration to the normal was the fastest after SPV. Changes in the discharge frequency after SPV did not differ much from those in the normal stomach and other types of vagotomy. With SPV, the decrease in the propagation velocity of basic electrical rhythms (BER) was mild, and a pattern similar to the control was shown compared with TV and SV. The antiperistaltic discharge was observed even with SPV, but the frequency was low compared with TV and SV. The frequency of peristaltic discharge was the highest when pyloroplasty was performed in addition to SPV. The responses to vagostigmine, insulin tetragastrin in SPV were similar to those in the normal stomach. During the gastric emptying time, there was neither difference before and after SPV, nor any significant difference due to the presence or absence of pyloroplasty. The above data show that SPV is advantageous for retaining the function of gastric peristalsis, also for gastric secretion, but the addition of pyloroplasty will not be advantageous for the elimination of gastric content.     

Antral compensation after proximal gastric vagotomy

Proximal gastric vagotomy (PGV) has little impact on the normal pattern of solid gastric emptying, despite denervation of the proximal two thirds of the stomach and loss of the proximal gastric pump. In four healthy volunteers and four patients with PGV, we investigated the possible compensatory mechanisms that may come into play after proximal denervation of the stomach. We measured antropyloroduodenal motility with a 10-lumen sleeve/side-hole catheter for 180 minutes after ingestion of a dual-isotope radiolabeled mixed liquid/solid meal. Patients with PGV exhibited faster liquid emptying, but the rate of solid emptying was similar to that in healthy volunteers. The frequency of propagated antropyloric pressure waves was similar between the two groups, but patients with PGV exhibited less isolated pressure waves in the proximal antrum. The amplitude and duration of pressure waves recorded in the distal antrum were significantly increased in the PGV patients as compared to healthy volunteers. Although the pattern of propagated antral contractions and solid gastric emptying remains unchanged after PGV, there is an increase in the amplitude and duration of distal antral contractions, which may compensate for loss of proximal gastric pumping mechanisms.     

Results of elective duodenal ulcer surgery in women: comparison of truncal vagotomy and antrectomy, gastric selective vagotomy and pyloroplasty, proximal gastric vagotomy.

This study provides a retrospective comparative analysis of results in 90 women patients who underwent three different elective operations for intractable duodenal ulcer disease. Group I (30 patients) underwent truncal vagotomy/antrectomy (TV + A); group II (30 patients) gastric selective vagotomy/pyloroplasty (GSV + P); and Group III proximal gastric vagotomy (PGV). There were no operative deaths among the 90 patients. No patient after TV + A has developed a recurrent ulcer. Two recurrent ulcers developed after GSV + P, and one gastric ulcer occurred after PGV. Dumping, diarrhea, and reflux gastritis were lower after PGV than with TV + A and GSV + P. Follow-up studies have been from six months to ten years. The clinical results among the three groups of women patients compare favorably with results obtained in a recent prospective randomized study using the identical operative procedures in three groups of men patients operated upon for intractability. There was no statistically significant difference between women and men after similar operative procedures, but the postgastrectomy sequelae were less after PGV in both women and men patients.     

Effects of general anaesthesia with enflurane on antroduodenal motility, pH and gastric emptying rate in man

Antroduodenal motility, pH and gastric emptying rate were investigated before, during and after general anaesthesia with enflurane in 11 patients undergoing elective surgery not involving the abdomen. Motility was measured by manometry and the gastric emptying rate by the rate of paracetamol absorption. During anaesthesia gastric emptying rate was delayed in nine patients. General anaesthesia with enflurane nearly abolished the motility in the antrum. The duration of successive interdigestive motor complexes was reduced (P less than 0.001) mainly be a reduction in Phase II (P less than 0.01). The frequency of contractions was unchanged in the duodenum during Phase II and decreased during Phase III (P less than 0.01). The amplitudes of contractions were unchanged in the proximal part of the duodenum and decreased in the distal part (P less than 0.01). General anaesthesia with enflurane increased the gastric pH per- and post-operatively (P less than 0.01). Motility in the antrum was rapidly regained in the recovery period. General anaesthesia with enflurane seems to delay gastric emptying rate by affecting the motility in the gastric antrum. The acidity of the stomach contents is reduced.     

Gastric tissue prostaglandin levels. Effect of vagotomy.

To determine tissue prostaglandin levels in antrum and fundus and to examine the effect of vagotomy and distention on tissue prostaglandin levels, truncal and parietal cell vagotomies were performed on rats that were killed at 2, 4, and 6 weeks postoperatively with antral and fundic prostaglandin E1 levels being determined. The fundus has considerably higher levels of prostaglandin than the antrum. No differences after any type of vagotomy however, were noted. It cannot be concluded from this study that increased prostaglandin levels result from vagotomy.     

Electromechanical contractive activity of the stomach and duodenum of conscious dogs

Studies were conducted in three conscious dogs implanted with electrodes and force transducers on the gastric antrum and duodenum. During the period of development of the interdigestive myoelectric complex (IMC) or the interdigestive contractions, intervals of development and amplitudes of the basic electric rhythm (BER) in the antrum varied markedly in contrast with those during the period of motor quiescence. In the antrum and duodenum, the frequency of BER decreased during IMC, and transiently increased after the end of IMC. After feeding, action potentials were superimposed on every BER of the antrum which occurred regularily, and a contraction accompanied each group of action potentials. While, in the duodenum, the percentage of BER's with action potentials was about 40%. The frequency of BER decreased in the antrum and increased in the duodenum compared with that before feeding. Wave form of action potentials and/or amplitude of contractions varied and the maximum amplitude of the contractions in the digestive state never exceeded that of the interdigestive contractions. Ratio of BER frequency of the duodenum to that of the antrum was 3.7-4.4 during the motor quiescence, while, during the period of development of the interdigestive contractions and the contractions in fed state, it was relatively high (4.3-4.6). Coinciding with the strong contractions among the interdigestive contractions of the antrum, diminution of the high-amplitude contractions in the duodenum was observed. On the other hand, in the digestive state, cyclic occurrence of a contraction in the antrum approximately corresponded in time with occurrence of contractions in the duodenum.     

Gastrointestinal Motility After Digestive Surgery

Gastrointestinal (GI) motility dysfunction is a common complication of any abdominal surgical procedure. During fasting, the upper GI tract undergoes a cyclic change in motor activity, called the interdigestive migrating motor contraction (IMC). The IMC is divided into four phases, with phase III having the most characteristic activity. After digestive surgery, GI motility dysfunction shows a lack of a fed response, less phase II activity, more frequent phase III activity of the IMC, and some phase III activity migrating orally. Postoperative symptoms have been related to motor disturbances, such as interrupted or retrograde phase III or low postprandial activity. The causes of GI disorder are autonomic nervous dysfunction and GI hormone disruptions. The administration of a motilin agonist can induce earlier phase III contractions in the stomach after pancreatoduodenectomy. For nervous dysfunction, an inhibitory sympathetic reflux is likely to be important in postoperative motility disorders. Until recently, treatment for gut dysmotility has consisted of nasogastric suction, intravenous fluids, and observation; however, more effective treatment methods are being reported. Recent discoveries have the potential to decrease postoperative gut dysmotility remarkably after surgery.     

Effects of truncal vagotomy on serum motilin levels, gastric motility patterns and gastric emptying: an experimental study

Using adult mongrel dogs, gastroduodenal motility, gastric emptying and pertinent serum motilin levels were measured under conscious states before and after transthoracic truncal vagotomy. Gastroduodenal motility was recorded by chronically planted strain gage transducers along the gastrointestinal tract. Gastric emptying was measured by X-ray examinations after barium-meat-meal ingestions or by gastric contents sampling method through the total pouch cannula after normal dog food ingestions. Results were as follows; Gastric motility patterns recorded by strain gage transducers were classified into two patterns that were a digestive pattern (D.P.) and an interdigestive pattern (I.P.). Serum motilin levels were elevated during high-amplitude contractions and lowered during resting phase of interdigestive periods. After vagotomy, strengths (heights) of antral contractions and phasic changes were decreased with the lack of I.P. These postvagotomy changes were thought to be related with the delayed gastric emptying after vagotomy. Gastric lavage through the cannula or pyloroplasty produced no effect on recovery of I.P. This fact suggested that the lack of I.P. was the direct effect of vagotomy and not due to delayed gastric contents emptying. On the assumption that motilin had the major role on the regulation of I.P., vagotomy seemed to produce an effect to prevent phasic motilin release.     

Effects of various operations on the electrical activity of the human stomach recorded during the postoperative recovery period.

This study attempts to characterize any changes occurring in the human gastric control electrical rhythm (CER), following a variety of gastric surgical procedures. Pairs of electrodes were implanted in selected specific sites on the stomachs of 57 patients undergoing either antrectomy and vagotomy, proximal gastric vagotomy (PGV), vagotomy and drainage, gastric resection without vagotomy, or fundoplication. Five patients undergoing nongastric operations served as controls. After operation recordings were obtained with differential preamplifiers, an oscilloscope, and a dual-channel tape recorder. An electrical signal compatible with a CER was found almost always in the distal body or antrum, regardless of whether vagotomy was performed. In contrast, a CER was found only occasionally in the fundus, and was never found following PGV. Although there was a difference in the frequency of occurrence of fundic CER in patients with and without vagotomy, it was not statistically significant (p = 0.0668). Patients with prolonged postoperative convalescence because of gastric atony were compared with patients with normal postoperative courses regarding the presence or absence of CER in the gastric antrum or fundus. A statistically significant relationship between abnormal gastric motility and absence of CER was not established.