Atrial flutter is a type of arrhythmia, or irregular heartbeat, that can cause palpitations, shortness of breath, and chest pain. The best lead to identify atrial flutter is an electrocardiogram (ECG) which shows an abnormal heart rhythm. An ECG can detect atrial flutter by measuring the electrical activity of the heart over a period of time. It can also determine the type, rate, and duration of the flutter. Other leads that can identify atrial flutter are a Holter monitor, which is a continuous recording of ECG activity for 24 hours or more, and a signal-averaged ECG, which is used to detect very low-amplitude signals that may be associated with flutter. Finally, an echocardiogram (ultrasound of the heart) can be used to identify any structural abnormalities that may be causing the flutter.