Most cases of sudden cardiac death result from V-Fib. Supraventricular Arrhythmias Atrial Tachycardia is a rapid rhythm originating in the atria, usually due to chronic disease processes. Not as dangerous as ventricular tachycardia. Multifocal atrial tachycardia is a variant of atrial tachycardia that results from lung disease. Atrial Fibrillation is an irregular heart rhythm, usually rapid at onset, originating in the atria.
Atrial fibrillation is the most common supraventricular arrhythmia in the aviation population.
Causes of atrial fibrillation include hyperthyroidism, heart valve abnormalities, and dilation of the atria. Dizziness, shortness of breath, mental confusion, or loss of consciousness may occur with atrial fibrillation if the ventricular response is too rapid or too slow. Bradyarrhythmias are slow heart rates defined as having a rate less than sixty beats per minute. Athletes and other aerobically fit individuals may commonly have heart rates in the 40-60 beats per minute range and experience no symptoms whatsoever. They are noteworthy in that, should further damage occur to the heart's conduction system, impulses meant to generate a heartbeat might not be conducted, with a dangerously slow heart rate resulting.