| Subject | Contents |
| Definition | A test that records the electrical activity of the heart. The ECG is used to measure the rate and regularity of beats as well as the size and position of the chambers, any damage to the heart, and effects of drugs or devices to regulate the heart (pacemaker). See also exercise treadmill ECG , Holter monitor (24h) . |
| Alternative Names | Electrocardiogram; EKG |
| How the test is performed | You are asked to lie down, and electrodes are affixed to each arm, leg, and the chest. This requires cleaning the site and, if necessary, shaving or clipping the hair. The standard number of leads attached is 12 to 15 for a "diagnostic" ECG, but may be as few as 3 to 5 for a "monitoring" ECG. You are usually required to remain still and may be asked to hold your breath for short periods during the procedure. Sometimes this test is performed while you are exercising or under minimal stress to monitor changes in the heart (see exercise treadmill ECG ). The results are recorded on graph paper. |
| How to prepare for the test | Adults: Tell the health care provider if you are taking any medications. There are no restrictions for food or fluids. However, ingestion of cold water immediately before an ECG may produce changes in one of the waveforms recorded (the T wave). Exercise (such as climbing stairs) immediately before an ECG may significantly increase your heart rate. Remove all jewelry. You may be asked to wear a hospital gown. Infants and children: The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age: infant test or procedure preparation (birth to 1 year) toddler test or procedure preparation (1 to 3 years) preschooler test or procedure preparation (3 to 6 years) schoolage test or procedure preparation (6 to 12 years) adolescent test or procedure preparation (12 to 18 years) |
| How the test will feel | An ECG is painless. When first applied, the disks may be cold and in rare circumstances, a person may develop a localized rash or irritation where the patches are placed. |
| Why the test is performed | An ECG is very useful in determining whether a person has heart disease . If a person has chest pain or palpitations , an ECG is helpful in determining if the heart is beating normally. If a person is on medications that may affect the heart or if the patient is on a pacemaker, an ECG can readily determine the immediate effects of changes in activity or medication levels. An ECG may be included as part of a routine examination in patients over 40 years old. |
| Normal Values | Heart Rate : 50 to 100 beats per minute. Rhythm: consistent and even. |
| What abnormal results mean | There may be: a myocardial (cardiac muscle) defect enlargement of the heart congenital defects heart valve disease arrhythmias ( abnormal rhythms ) tachycardia or bradycardia ( heart rate too fast or slow) ectopic heartbeatcoronary artery diseaseinflammation of the heart ( myocarditis ) changes in the amount of electrolytes (chemicals in the blood) a past heart attack a present or impending heart attack Additional conditions under which the test may be performed: alcoholic cardiomyopathyanorexia nervosaaortic dissectionaortic insufficiencyaortic stenosisatrial fibrillation/flutteratrial myxoma; leftatrial myxoma; rightatrial septal defectcardiac tamponadecoarctation of the aortacomplicated alcohol abstinence (delirium tremens)coronary artery spasmdigitalis toxicitydilated cardiomyopathydrug-induced lupus erythematosusfamilial periodic paralysisGuillain-Barreheart failurehyperkalemiahypertensive heart diseasehypertrophic cardiomyopathyhypoparathyroidismidiopathic cardiomyopathyinfective endocarditis insomnia ischemic cardiomyopathyleft-sided heart failureLyme disease mitral regurgitation; acutemitral regurgitation; chronicmitral stenosismitral valve prolapsemultifocal atrial tachycardianarcolepsynoninsulin-dependent diabetes mellitus (NIDDM)obstructive sleep apneaparoxysmal supraventricular tachycardiapatent ductus arteriosuspericarditispericarditis; bacterialpericarditis; constrictivepericarditis; post-MIperipartum cardiomyopathyprimary amyloidprimary hyperaldosteronismprimary hyperparathyroidismprimary pulmonary hypertensionpulmonary emboluspulmonary valve stenosisrestrictive cardiomyopathyright-sided heart failuresick sinus syndromestable anginastrokesystemic lupus erythematosustetralogy of Fallotthyrotoxic periodic paralysistransient ischemic attack (TIA)transposition of the great vesselstricuspid regurgitationunstable anginaventricular septal defectventricular tachycardiaWolff-Parkinson-White syndrome |
| What the risks are | There are generally no risks. Since this procedure only monitors the electrical impulses and does not emit electricity, there is no risk of shock. During an exercise electrocardiogram, some patients experience arrhythmias or heart distress. Equipment for dealing with these occurrences is located in the testing area. |
| Special considerations | The accuracy of the ECG varies with the condition being tested. Some heart conditions are not detectable all the time, and others may never produce any specific ECG changes. A person who suspects heart disease or has had a heart attack may need more than one ECG. There is no reason for healthy people to undergo annual testing unless they have inherited risks or a medical condition. It is important to be relaxed and relatively warm during ECG recording, because muscle tremor alters the tracing. |
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