ECG is a simple, painless and safe procedure to detect various heart problems in a patient. The procedure helps the doctor to diagnose the heart related problems at an early stage. Some of the abnormalities detected by the ECG are as follows:

• Defects in the heart
• The irregular rhythm of the heart, also known as arrhythmias.
• Narrowed or obstructed arteries in the heart (coronary artery disease)
• To check damage to the heart after a heart attack
• A heart attack in emergencies.
• Congenital heart defects
• Abnormal electrolyte balance in the blood (calcium, potassium, magnesium, etc.)
• Thickened muscles of the heart. This condition is also known as hypertrophy.
• Harmful effects on the heart from some lung conditions e.g. pulmonary embolus, blood clots to the lungs and emphysema.
• Harmful effects on the heart from various systemic or heart diseases like thyroid disease or hypertension.
• Improper blood flow or blood circulation in the heart. This is also known as ischemia.
• Abnormal cardiac impulse conduction which may be due to metabolic or cardiac diseases.

ECG is also advised if there are any of the following symptoms observed by the doctor:

• Chest pain
• Shortness of breath
• Dizziness
• Fatigue
• Very fast heartbeat

There are certain other conditions, wherein the patient has to undergo the ECG. These conditions are as mentioned below:

• Any family history of heart attack or stroke.
• Any past personal history of a heart attack or severe chest pain.
• Any scheduled surgical procedure of the heart, which may need an ECG, in order to check the condition of the heart before the surgery.
• In order to check the effectiveness of medicines given to improve the condition of the heart.
• To monitor the effective working of an electrical device known as a pacemaker (artificial heart).

An electrocardiogram is a noninvasive and safe procedure to monitor the electrical signals in the heart. Some patients might face some discomfort or uneasiness when the electrodes or the test sensors are removed from the patient’s body. The level of discomfort is similar to the discomfort faced when a band-aid is removed from the skin. A few patients might develop some skin reactions from the adhesives which are used to put electrodes on the patient’s body. In some rare cases, patients might get some swelling and redness on the area where electrodes are placed. There is no risk of electrocution from the electrodes during an ECG as these electrodes attached to the patient's body do not emit any electricity.

In the stress echocardiogram, there is an ECG done along with the echo test. In this test, when the heart of the patient is put under stress (when a patient is asked to walk on a treadmill), in some rare cases, the patient might get a heart attack. This may happen as a result of an irregular heartbeat due to physical activity done during the stress test.

There is another type of stress echo known as a Dobutamine stress test, which includes an ECG test to be conducted for the patient. If the patient is not able to perform an exercise or walk on the treadmill, then an injection is given with a drug, that makes the heart pump faster as if the patient is exercising. Some patients also develop adverse reactions from the drug given in this test.

It is important for a patient to inform the doctor about any allergic reactions, if happened in the past or any medicines a patient is taking. In such cases, the doctor will assess the current state and the medications prescribed and would either ask the patient to stop taking the medicine or continue if there are no side effects.

The doctor or the nurse will explain the ECG procedure in detail to the patient. No specific preparations are required before the test. Some points to be taken care of are as mentioned:

• The patient is advised to avoid taking any cold fluids before the ECG test. This is because the intake of cold fluids or water might give misleading readings in the ECG graph and in the electrical patterns recorded.
• The patient is advised to avoid doing strenuous physical exercises or even climbing stairs before the ECG test as this may lead to an increase in the heart rate and may produce false-positive results.
• The patient is asked to avoid applying any oily creams or lotions before the procedure as this may prevent the electrodes from sticking properly to the patient’s body.
• The patient is asked to change into a hospital gown before going for the procedure.
• The procedure is done in the outpatient facility.

During the procedure:

There is no need for hospitalization before the procedure. The patient is asked to remove the clothes from the upper half of the body or change into a hospital gown. The patient is then made to lie down on an examination table on the back. The nurse or the technician attaches electrodes or test sensors to the patient’s body with the help of some adhesive tapes. This is done in order to detect the electric currents of the patient’s heart. Usually, 12 to 15 electrodes will be attached to the patient's chest, arms, and legs. These electrode patches are attached to the body with the help of a gel. If the patient has dense hair on the areas where electrodes are to be applied, the technician might as well shave the small area for the electrodes to stick properly as if the electrodes are not stuck properly, the ECG readings might not be very accurate.

The patient can breathe normally during the test but should try to lie still during an ECG test. This is because any movement, shivering or talking during the ECG, may distort or give abrupt results. The ECG test usually takes a few minutes to complete. If there is any irregularity in the heartbeat observed during the test, the doctor may advise some other types of ECG tests as highlighted below.

• Holter monitoring – This is a portable, ambulatory electrocardiography monitor which helps in recording cardiac rhythms or cardiac activity for at least 24 or 48 hours. In this type of ECG, the electrode wires attached on the patient’s chest are connected with a small device operated with a battery. This device can be carried in the pocket, worn on a shoulder strap or belt. When a Holter is attached, the patient is asked to maintain a diary of the activities done in the entire day along with the timings and any symptoms noticed. The doctor will then compare the recordings in the Holter with the activities mentioned in the diary. This would further enable the doctor to understand the symptoms related to the activity done and changes in the electrical signals.
• Event recorder – The patients are advised to wear an event recorder if the symptoms do not occur very often. This is almost similar to the Holter device but only records the cardiac rhythm when any symptom occurs. The patient can also send the ECG readings through the phone to the doctor.
• Stress test – The stress test, consisting of an ECG, is advised when the heart of the patient is unable to perform or function properly under stress. During this test, the patient might be asked to walk on a treadmill, however, in some rare cases, the patient might get a heart attack during the stress test or while walking on the treadmill. This may happen because of an irregular heartbeat due to physical activity done during the stress test.
• There is another type of stress echo known as a Dobutamine stress test, which includes an ECG test to be conducted for the patient. If the patient is not able to perform an exercise or walk on the treadmill, then an injection is given with a drug, that makes the heart pump faster as if the patient is exercising. This test is usually done to detect heart problems that occur while performing physical activity.

After the procedure:

After the procedure, the electrodes are removed from the patient’s body. The gel, applied to attach the electrodes, is wiped off with a soft tissue. The patient is asked to put on normal clothes and is allowed to go back home after the procedure and resume normal routine activities.

It takes only a few minutes to perform a standard ECG test. The results are also made available and can be discussed with the patient the same day the ECG is performed.

The doctor will discuss the results of the ECG report in detail with the patient. If the results are normal, it means that the patient is fit and healthy and no abnormality is detected. The cardiac rhythms and the functioning of the heart is normal i.e. 50 to 100 beats per minute. However, if the results are abnormal, then the doctor may advise a treatment plan or medicines to the patient.

In case, the doctor is not clear about the results, then some other diagnostic tests e.g. echocardiogram, may be advised to the patient or the patient might be asked to repeat the ECG test.

There can be multiple abnormalities detected, based on the results from the ECG procedure and the  doctor would provide treatment according to the abnormality detected. Some of the abnormalities detected are as mentioned:

• Abnormal heart rate – Usually heart rate can be recorded through the pulse rate. But if a patient has a feeble pulse, then ECG is helpful in recording irregular, too slow or too fast heart beats.
• Abnormal heart rhythm – ECG test can help to detect tachycardia (very fast heartbeat), bradycardia (very slow heartbeat) and arrhythmia (irregular heartbeat). Some medications such as psychotropic drugs, beta blockers or amphetamines may trigger arrhythmia.
• Insufficient oxygen and blood supply to the heart – ECG assists the doctor to understand the cause of the chest pain, which may be due to the insufficient supply of oxygen and blood to the heart.
• Structural defects or abnormalities – ECG helps in detecting heart problems like cardiomegaly (enlarged heart) or even congenital heart disorders. It may also be helpful in identifying bulge in the walls of the heart known as an aneurysm.
• Heart attacks - Any evidence of past heart attack or severe chest pain can be identified through an ECG.