Transient lower esophageal sphincter

Gastroesophageal reflux occurs in approximately 18% of infants. As in adults, transient lower esophageal sphincter relaxations appear to be the most common cause of GERD.26 This is due to developmental immaturity of the lower esophageal sphincter.27 Other causes include impaired luminal clearance of gastric acid, neurologic impairment, and type of infant formula. 

Morphine reduces the rate of transient lower esophageal sphincter relaxation in patients with reflux disease, thus reducing the number of reflux episodes the effect was reversed by naloxone (SEDA-22,12). 

Lehmann A, Blackshaw LA, Branden L, Carlsson A, Jensen J, Nygren E, Smid SD (2002) Cannabinoid receptor agonism inhibits transient lower esophageal sphincter relaxations and reflux in dogs. Gastroenterology 123 1129-1134... 

Boeckxstaens GE, Hirsch DP, Fakhry N, et al. Involvement of cholecystokinin-A receptors in transient lower esophageal sphincter relaxations triggered by gastric distension. Am J Gastroenterol 1998 93 1823-1828. 

Boulant J, Fioramonti J, Dapoigny M, et al. Cholecystokinin and nitric oxide in transient lower esophageal sphincter relaxation to gastric distention in dogs. Gastroenterology 1994 107 1059-1066. 

Hirsch DP, Holloway RH, Tytgat GN, et al. Involvement of nitric oxide in human transient lower esophageal sphincter relaxations and esophageal primary peristalsis. Gastroenterology 1998 115 374-380. 

Hirsch DP, Tiel-Van BUUI AAM, Tytgat GNJ, et al. Effect of L-NAAAAA on post-prandial transient lower esophageal sphincter relaxations in healthy volunteers [abstract]. Neurogastroenterol Motil 1999 11 264. 

Kahrilas PJ, Shi G, Manka M, et al. Increased frequency of transient lower esophageal sphincter relaxation induced by gastric distention in reflux patients with hiatal hernia. Gastroenterology 2000 118 688-695. 

Lidums I, Lehmann A, Checklin H, et al. Control of transient lower esophageal sphincter relaxations and reflux by the GABAr agonist baclofen in normal subjects. 

Mittal RK, Holloway RH, Penagini R, et al. Transient lower esophageal sphincter relaxation. Gastroenterology 1995 109 601-610. 

Penagini R, Bianchi PA. Effect of morphine on gastroesophageal reflux and transient lower esophageal sphincter relaxation. Gastroenterology 997 113 409-414. 

Second, reflux may occur after transient increases in intraabdominal pressure (stress reflux).3 An increase in intraabdominal pressure such as that occurring during straining, bending over, coughing, eating, or a Valsalva maneuver may overcome a weak lower esophageal sphincter, and thus may lead to reflux. 

Third, the lower esophageal sphincter may be atonic, thus permitting free reflux. Although transient relaxations are more likely to occur when there is normal lower esophageal sphincter pressure, the latter two mechanisms are more likely... 

In some cases, gastroesophageal reflux is associated with defective lower esophageal sphincter (LES) pressure or function. Patients may have decreased LES pressures related to spontaneous transient LES relaxations, transient increases in intraabdominal pressure, or an atonic LES. A variety of foods and medications may decrease LES pressure (Table 24-1). 

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