The American frontier comprises the geography, history, folklore, and cultural expression of life in the forward wave of American westward expansion that began with English colonial settlements in the early 17th century and ended with the admission of the last mainland territories as states in 1912.
Atrial Flutter Causes. Atrial flutter may be caused by abnormalities or diseases of the heart, by a disease elsewhere in the body that affects the heart, or by consumption of substances that change the way electrical impulses are transmitted through the heart. In some people, no underlying cause is ever found.
This type of atrial flutter is referred to as typical atrial flutter. Less commonly, atrial flutter can result from circuits in other areas of the right or left atrium that cause the heart to beat fast. Atrial flutter that results from these less common types of circuits is referred to as atypical atrial flutter.