This is a medical question of type : exams and tests 
 How to diagnose Arrhythmia ? 
 Arrhythmias can be hard to diagnose, especially the types that only cause symptoms every once in a while. Doctors diagnose arrhythmias based on medical and family histories, a physical exam, and the results from tests and procedures.
                
Specialists Involved
                
Doctors who specialize in the diagnosis and treatment of heart diseases include:
                
Cardiologists. These doctors diagnose and treat adults who have heart problems.
                
Pediatric cardiologists. These doctors diagnose and treat babies, children, and youth who have heart problems.
                
Electrophysiologists. These doctors are cardiologists or pediatric cardiologists who specialize in arrhythmias.
                
Medical and Family Histories
                
To diagnose an arrhythmia, your doctor may ask you to describe your symptoms. He or she may ask whether you feel fluttering in your chest and whether you feel dizzy or light-headed.
                
Your doctor also may ask whether you have other health problems, such as a history of heart disease, high blood pressure, diabetes, or thyroid problems. He or she may ask about your family's medical history, including whether anyone in your family:
                
Has a history of arrhythmias
                
Has ever had heart disease or high blood pressure
                
Has died suddenly
                
Has other illnesses or health problems
                
Your doctor will likely want to know what medicines you're taking, including over-the-counter medicines and supplements.
                
Your doctor may ask about your health habits, such as physical activity, smoking, or using alcohol or drugs (for example, cocaine). He or she also may want to know whether you've had emotional stress or anger.
                
Physical Exam
                
During a physical exam, your doctor may:
                
Listen to the rate and rhythm of your heartbeat
                
Listen to your heart for a heart murmur (an extra or unusual sound heard during your heartbeat)
                
Check your pulse to find out how fast your heart is beating
                
Check for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure
                
Look for signs of other diseases, such as thyroid disease, that could be causing the problem
                
Diagnostic Tests and Procedures
                
EKG (Electrocardiogram)
                
An EKG is a simple, painless test that detects and records the heart's electrical activity. It's the most common test used to diagnose arrhythmias.
                
An EKG shows how fast the heart is beating and its rhythm (steady or irregular). It also records the strength and timing of electrical signals as they pass through the heart.
                
A standard EKG only records the heartbeat for a few seconds. It won't detect arrhythmias that don't happen during the test.
                
To diagnose arrhythmias that come and go, your doctor may have you wear a portable EKG monitor. The two most common types of portable EKGs are Holter and event monitors.
                
Holter and Event Monitors
                
A Holter monitor records the heart's electrical signals for a full 24- or 48-hour period. You wear one while you do your normal daily activities. This allows the monitor to record your heart for a longer time than a standard EKG.
                
An event monitor is similar to a Holter monitor. You wear an event monitor while doing your normal activities. However, an event monitor only records your heart's electrical activity at certain times while you're wearing it.
                
For many event monitors, you push a button to start the monitor when you feel symptoms. Other event monitors start automatically when they sense abnormal heart rhythms.
                
Some event monitors are able to send data about your heart's electrical activity to a central monitoring station. Technicians at the station review the information and send it to your doctor. You also can use the device to report any symptoms you're having.
                
You can wear an event monitor for weeks or until symptoms occur.
                
Other Tests
                
Other tests also are used to help diagnose arrhythmias.
                
Blood tests. Blood tests check the level of substances in the blood, such as potassium and thyroid hormone. Abnormal levels of these substances can increase your chances of having an arrhythmia.
                
Chest x ray. A chest x ray is a painless test that creates pictures of the structures in your chest, such as your heart and lungs. This test can show whether your heart is enlarged.
                
Echocardiography. This test uses sound waves to create a moving picture of your heart. Echocardiography (echo) provides information about the size and shape of your heart and how well your heart chambers and valves are working.
                
The test also can identify areas of poor blood flow to the heart, areas of heart muscle that aren't contracting normally, and previous injury to the heart muscle caused by poor blood flow.
                
There are several types of echo, including stress echo. This test is done both before and after a stress test (see below). A stress echo usually is done to find out whether you have decreased blood flow to your heart, a sign of coronary heart disease (CHD).
                
A transesophageal (tranz-ih-sof-uh-JEE-ul) echo, or TEE, is a special type of echo that takes pictures of the heart through the esophagus. The esophagus is the passage leading from your mouth to your stomach.
                
Stress test. Some heart problems are easier to diagnose when your heart is working hard and beating fast. During stress testing, you exercise to make your heart work hard and beat fast while heart tests are done. If you can't exercise, you may be given medicine to make your heart work hard and beat fast.
                
The heart tests done during stress testing may include nuclear heart scanning, echo, and positron emission tomography (PET) scanning of the heart.
                
Electrophysiology study (EPS). This test is used to assess serious arrhythmias. During an EPS, a thin, flexible wire is passed through a vein in your groin (upper thigh) or arm to your heart. The wire records your heart's electrical signals.
                
Your doctor can use the wire to electrically stimulate your heart and trigger an arrhythmia. This allows your doctor to see whether an antiarrhythmia medicine can stop the problem.
                
Catheter ablation, a procedure used to treat some arrhythmias, may be done during an EPS.
                
Tilt table testing. This test sometimes is used to help find the cause of fainting spells. You lie on a table that moves from a lying down to an upright position. The change in position may cause you to faint.
                
Your doctor watches your symptoms, heart rate, EKG reading, and blood pressure throughout the test. He or she may give you medicine and then check your response to the medicine.
                
Coronary angiography. Coronary angiography uses dye and special x rays to show the inside of your coronary arteries. To get the dye into your coronary arteries, your doctor will use a procedure called cardiac catheterization (KATH-e-ter-ih-ZA-shun).
                
A thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck. The tube is threaded into your coronary arteries, and the dye is released into your bloodstream.
                
Special x rays are taken while the dye is flowing through your coronary arteries. The dye lets your doctor study the flow of blood through your heart and blood vessels. This helps your doctor find blockages that can cause a heart attack.
                
Implantable loop recorder. This device detects abnormal heart rhythms. Minor surgery is used to place this device under the skin in the chest area.
                
An implantable loop recorder helps doctors figure out why a person may be having palpitations or fainting spells, especially if these symptoms don't happen very often. The device can be used for as long as 12 to 24 months.