Source:http://linkedlifedata.com/resource/umls/id/C0546959
NCI: Any rapid heart rhythm originating in the atria. Atrial fibrillation and atrial flutter are varieties of atrial tachycardia. Atrial tachycardia is an electrical circuit originating in the upper or atrial chambers. This electrical circuit or focus takes over and generates rapid impulses across the atrial chambers. These impulses are transmitted to the ventricular chambers resulting in a rapid rate. These arrhythmias may originate from a variety of places across the atria. They may exist as an isolated problem or be related to an ongoing structural problem within the heart. (NCI),NCI: The cardiac rhythm is greater than 100 beats per minute and originates from the atria or sinoatrial node.