Source:http://linkedlifedata.com/resource/umls/id/C1321523
NCI: A condition characterized by the site of origin of impulses, controlling the heart rate, changing within the atria, including the sinus node. Variations within P waves and PR intervals occur and an irregular rate of impulse formation is observed.,NCI: A condition characterized by the site of origin of impulses, controlling the heart rate, changing within the atria, including the sinus node. Variations within P waves and PR intervals occur and an irregular rate of impulse formation is observed. (NCI)