関: cardiospasm、esophageal achalasia

WordNet

a spasm of the cardiac sphincter (between the esophagus and the stomach); if the cardiac sphincter does not relax during swallowing the passage of food into the stomach is obstructed

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/01/15 21:38:25」(JST)

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Megaesophagus is a condition in humans, cats and dogs where peristalsis fails to occur properly and the esophagus is enlarged. Normally, when the animal's esophagus is functioning properly, it acts as a muscle and pushes the food down the esophagus into the stomach. However, when an animal has megaesophagus, the esophagus stays enlarged and does not push the food down to the stomach. Therefore, the food fails to enter the stomach and often stays in the esophagus, and is eventually regurgitated, or enters the lungs through breathing, or decays in the esophagus.

In human pathology a condition known as achalasia may predispose a person to slowly develop megaesophagus. Achalasia is due to the loss of ganglion cells of the myenteric plexus. It occurs mostly in middle aged adults. There is a marked lack of contraction within the muscles involved in peristalsis with a constant contraction of the lower esophageal sphincter. Dilation of the esophagus results in difficulty swallowing. Retention of food bolus is also noted. Chagas disease is one cause of megaesophagus in humans. Achalasia also predisposes to esophageal carcinoma.

Megaesophagus can also be a symptom of another disease in dogs called myasthenia gravis. Myasthenia gravis is a neuromuscular disease where the primary symptom is weakness in various body parts of the dog. However, when myasthenia gravis occurs in older dogs it is thought of as an immune-mediated disease. Often when myasthenia gravis is diagnosed in older dogs the first symptom the dog may manifest is megaesophagus.

Myasthenia gravis occurs when acetylcholine receptors (nicotinic acetylcholine receptors or AChRs) fail to function properly. Due to the inability of the nerve receptors to function appropriately, the muscles fail to have a stimulus that causes them to contract.

An important distinction in recognizing megaesophagus is the difference between when a dog regurgitates or vomits. Regurgitating is a common symptom of megaesophagus while vomiting is not necessarily associated with megaesophagus. When a dog regurgitates there is usually not as much effort involved as when a dog vomits. Often when regurgitating, the dog will tip its head down and the liquid and/or food will almost appear to "spill out" of its throat.

One of the primary dangers to a dog with megaesophagus is aspiration pneumonia. Because the food stays lodged in the throat, it can often be inhaled into the lungs causing aspiration pneumonia. One way to avoid this is to make sure that every time the dog eats or drinks anything, that the dog sits for at least 10 minutes afterwards or is held in a sitting up or begging position. This requires that all food and liquid intake be closely monitored and specifically administered to the dog in regular intervals (sometimes as often as 2–3 hours) in smaller quantities. Obviously, if smaller quantities of food and water are administered, one needs to take the necessary precaution to ensure the dog has a sufficient caloric and water intake. According to many specialists, this disorder has a guarded prognosis, however, since 2004 many owners have found a number of successful management techniques, one of which is vertical feeding (see "Bailey Chair megaesophagus").

Breeds Affected[edit]

American Shorthair
Corgis
Basset Fauve de Bretagne

Bernese Mountain Dogs

Boston Terrier
Dachshund
French Bulldog
German Shepherd Dog
Golden Retriever
Great Dane
Greyhound
Irish Setter
Italian Greyhound
Labrador Retriever
Miniature Schnauzer
Persian (cat)
Shar Pei
Shih Tzu
Siamese (cat)
Welsh Terrier
Wire Fox Terrier
Irish Wolfhound

An extensive list of breeds affected via known familial predisposition may be found at Genetic Predisposition

External links[edit]

http://www.caninemegaesophagus.org/
http://www.marvistavet.com/html/megaesophagus.html
http://www.upei.ca/~cidd/Diseases/GI%20disorders/megaesophagus.htm
http://www.gcvs.com/internists/megaesophagus.htm

UpToDate Contents

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1. 消化管のシャーガス病 gastrointestinal chagas disease
2. アカラシアの臨床症状および診断 clinical manifestations and diagnosis of achalasia
3. アカラシアの手術マネージメント：腹腔鏡下および開腹式ヘラー筋切開術 operative management of achalasia laparoscopic and open heller myotomy
4. シャーガス病の病理および病因 pathology and pathogenesis of chagas disease
5. シャーガス病：急性疾患、早期慢性疾患、および免疫不全宿主における疾患のマネージメント chagas disease management of acute disease early chronic disease and disease in immunocompromised hosts

English Journal

A stepwise approach for peroral endoscopic myotomy for treating achalasia: from animal models to patients.

Ren Y1, Tang X, Zhi F, Liu S, Wu J, Peng Y, Jiang B, Gong W.
Scandinavian journal of gastroenterology.Scand J Gastroenterol.2015 Aug;50(8):952-8. doi: 10.3109/00365521.2014.983152. Epub 2015 Apr 10.
OBJECTIVES: Peroral endoscopic myotomy (POEM) was initially developed for the treatment of achalasia. This study aimed to investigate the feasibility and safety of a stepwise approach for POEM in the management of achalasia.METHODS: A total of five ex-vivo porcine esophagus-stomach training models w
PMID 25861971

Achalasia Is Associated With eNOS4a4a, iNOS22GA, and nNOS29TT Genotypes: A Case-control Study.

Singh R1, Ghoshal UC1, Misra A1, Mittal B2.
Journal of neurogastroenterology and motility.J Neurogastroenterol Motil.2015 Jul 30;21(3):380-9. doi: 10.5056/jnm14123.
BACKGROUND/AIMS: Achalasia is known to result from degeneration of inhibitory neurons, which are mostly nitrinergic. Characteristic features of achalasia include incomplete lower esophageal sphincter (LES) relaxation and esophageal aperistalsis. Nitric oxide (NO), pro-duced by NO synthase (NOS), pla
PMID 26088023

The Pathogenesis and Management of Achalasia: Current Status and Future Directions.

Ates F1, Vaezi MF1.
Gut and liver.Gut Liver.2015 Jul 23;9(4):449-63. doi: 10.5009/gnl14446.
Achalasia is an esophageal motility disorder that is commonly misdiagnosed initially as gastroesophageal reflux disease. Patients with achalasia often complain of dysphagia with solids and liquids but may focus on regurgitation as the primary symptom, leading to initial misdiagnosis. Diagnostic test
PMID 26087861

Japanese Journal

from COMPENDIUM 消化器巨大食道症

Mace Sacha,Shelton G. Diane,Eddlestone Susan [他]
J-vet : EBM & informed consent 25(9), 17-27,96, 2012-09
NAID 40019435626

Acute Airway Obstruction in a Patient with Achalasia

Miyamoto Shin'ichi,Konda Yoshitaka,Matsui Masashi,Sawada Kazuya,Ikeda Kazuki,Watanabe Norihiko,Kawanami Chiharu,Chiba Tsutomu
Internal Medicine 50(20), 2333-2336, 2011
… Megaesophagus resulting from achalasia is a rare but serious cause of acute airway obstruction. …
NAID 130001087742