This is a medical question of type : exams and tests 
 How to diagnose Heart Palpitations ? 
 First, your doctor will want to find out whether your palpitations are harmless or related to a heart problem. He or she will ask about your symptoms and medical history, do a physical exam, and recommend several basic tests.
                
This information may point to a heart problem as the cause of your palpitations. If so, your doctor may recommend more tests. These tests will help show what the problem is, so your doctor can decide how to treat it.
                
The cause of palpitations may be hard to diagnose, especially if symptoms don't occur regularly.
                
Specialists Involved
                
Several types of doctors may work with you to diagnose and treat your palpitations. These include a:
                
Primary care doctor
                
Cardiologist (a doctor who specializes in diagnosing and treating heart diseases and conditions)
                
Electrophysiologist (a cardiologist who specializes in the heart's electrical system)
                
Medical History
                
Your doctor will ask questions about your palpitations, such as:
                
When did they begin?
                
How long do they last?
                
How often do they occur?
                
Do they start and stop suddenly?
                
Does your heartbeat feel steady or irregular during the palpitations?
                
Do other symptoms occur with the palpitations?
                
Do your palpitations have a pattern? For example, do they occur when you exercise or drink coffee? Do they happen at a certain time of day?
                
Your doctor also may ask about your use of caffeine, alcohol, supplements, and illegal drugs.
                
Physical Exam
                
Your doctor will take your pulse to find out how fast your heart is beating and whether its rhythm is normal. He or she also will use a stethoscope to listen to your heartbeat.
                
Your doctor may look for signs of conditions that can cause palpitations, such as an overactive thyroid.
                
Diagnostic Tests
                
Often, the first test that's done is an EKG (electrocardiogram). This simple test records your heart's electrical activity.
                
An EKG shows how fast your heart is beating and its rhythm (steady or irregular). It also records the strength and timing of electrical signals as they pass through your heart.
                
Even if your EKG results are normal, you may still have a medical condition that's causing palpitations. If your doctor suspects this is the case, you may have blood tests to gather more information about your heart's structure, function, and electrical system.
                
Holter or Event Monitor
                
A standard EKG only records the heartbeat for a few seconds. It won't detect heart rhythm problems that don't happen during the test. To diagnose problems that come and go, your doctor may have you wear a Holter or event monitor.
                
A Holter monitor records the hearts electrical activity for a full 24- or 48-hour period. You wear patches called electrodes on your chest. Wires connect the patches to a small, portable recorder. The recorder can be clipped to a belt, kept in a pocket, or hung around your neck.
                
During the 24- or 48-hour period, you do your usual daily activities. You use a notebook to record any symptoms you have and the time they occur. You then return both the recorder and the notebook to your doctor to read the results. Your doctor can see how your heart was beating at the time you had symptoms.
                
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.
                
You can wear an event monitor for weeks or until symptoms occur.
                
Holter or Event Monitor
                

                
Echocardiography
                
Echocardiography uses sound waves to create a moving picture of your heart. The picture shows 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.
                
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 cant exercise, you may be given medicine to make your heart work hard and beat fast.