The primary difference between flutter and atrial tachycardia is the type of arrhythmia they represent. Atrial tachycardia is a type of supraventricular tachycardia (SVT) that is characterized by rapid, regular atrial activity. It can be seen as a regular, narrow-complex, tachycardia on an electrocardiogram (ECG). Flutter, on the other hand, is a type of atrial fibrillation (AF) and is characterized by rapid, irregular atrial activity. It can be seen as an irregular, wide-complex, tachycardia on an ECG.
Atrial tachycardia is usually caused by abnormal automaticity of the sinoatrial (SA) or atrioventricular (AV) nodes, while atrial flutter is usually caused by reentrant circuit activity. In addition, atrial tachycardia is often associated with a short PR interval, while atrial flutter is associated with a longer PR interval.
Another way to tell the difference between flutter and atrial tachycardia is to look for atrial flutter waves (F-waves) on the ECG. Atrial flutter waves are saw-tooth like waves that occur at a rate of about 300-400 beats per minute and are usually seen in the inferior leads. Atrial tachycardia does not typically produce F-waves.
Finally, the presence of an atrial rate greater than 200 beats per minute is a strong indication of atrial flutter, while an atrial rate of less than 200 beats per minute is usually indicative of atrial tachycardia.
In summary, the primary difference between flutter and atrial tachycardia is the type of arrhythmia they represent. Other distinguishing features include the mechanism of the arrhythmia, the PR interval, the presence of F-waves, and the atrial rate.