Upon hearing about the symptoms, the health-care professional (whether a primary care provider or a provider in the emergency department) may suspect an arrhythmia. Because many different arrhythmias can cause similar symptoms, the evaluation at first focuses on ruling out the most dangerous ones. One simple test, the electrocardiogram (ECG), can help tell a lot about what is happening with the heart.

The ECG measures and records the electrical impulses that control the beating of the heart.

__The ECG findings highlight irregularities in the heartbeat and abnormalities in the heart.

__In arrhythmias, the ECG tracings can help pinpoint the type of arrhythmia and where it comes from in the heart.

__The ECG also shows signs of heart attack, heart ischemia, abnormal heart enlargement (hypertrophy), conduction abnormalities, and certain chemical and electrolyte abnormalities in the heart tissue.

People sometimes have symptoms suggesting arrhythmias, but when the ECG is recorded, the result is normal. This may mean that the arrhythmia comes and goes (paroxysmal atrial flutter), a common condition, or it may mean an arrhythmia does not exist, and the heart feels odd or jumpy because of other factors, such as anxiety. If the ECG result is normal, an ambulatory ECG may be performed for 24 hours using a Holter monitor or for a longer period using an event monitor.

An ambulatory ECG involves a person wearing a monitoring device for a few days while going about normal activities. The purpose of an ambulatory ECG is to obtain documented proof of the arrhythmia. Proof is important because treatment depends upon identification of the arrhythmia.

__One device is known as a Holter monitor and usually records the heart rhythm on a continual basis for 24-48 hours.

__Some health care providers prefer that the device is worn for longer than 24-48 hours, with intermittent recording of the heart rhythm. In these cases, an event recorder is used.

__Both the Holter monitor and the event recorder work well. The important thing is to obtain ECG documentation of the arrhythmia, if it exists.

An echocardiogram is an ultrasound test that uses sound waves to make a picture of the inside of the heart while it is beating. In this test, an ultrasound probe is positioned on the outer chest wall, and the images obtained are viewed on a monitor.

__This test is performed to identify heart valve problems, to check ventricular function, or to look for blood clots in the atria.

__This safe, non-invasive test uses the same technique that is used to evaluate a fetus during pregnancy.

__This test is not always performed in the emergency department.

Occasionally, atrial flutter is detected in people with no symptoms when they see their health care provider for another reason. The health care provider may notice unusual heart sounds or an unusual pulse on physical exam, and he or she may order an ECG.