An electrocardiogram, also referred to as an ECG or EKG, is a recording of the electrical current in the heart. An electrocardiograph produces a strip graph of the recorded electrical activity and provides results for the doctor to determine abnormalities in the heart. A doctor may request an electrocardiogram as a preventative screening tool for an individual with a family history of heart disease or if symptoms of heart problems are present. Symptoms that may warrant an ECG include chest pain, nausea, shortness of breath, weakness, palpitations, abdominal pain, fainting and anxiety.
Holter Monitor
An abnormal ECG is often caused by an arrhythmia, or an irregular heartbeat. In some cases, arrhythmias are not constant, making it hard to document on an ECG during a visit to the doctor. A Holter monitor is a portable ECG that will record every heartbeat for a 24-hour period or longer. Monitoring the electrical activity for a significant period of time will increase the possibility of finding an abnormal ECG.
Normal ECG
A normal heartbeat has a P wave, a QRS complex and a T wave. The P wave measures the atrial contraction, the QRS measures ventricle contraction and the T wave measures ventricular repolarization. According to Medline Plus, the heart rhythm should be stable and consistent, with the heart rate between 60 and 100 beats per minute.
Abnormal ECG
Abnormalities are found by comparing results with a normal ECG graph. Sometimes the P, QRS and T waves can display abnormalities in the electrical conduction system of the heart and malfunction of the heart muscle tissue. These abnormalities may be a sign of several health concerns, but the doctor may pursue additional tests to rule out a false reading to see if a problem really exists.
Arrhythmias
It is unusual for a healthy heart to experience a lengthy arrhythmia without the onset of a condition that would change the structure of the heart. The occasional irregular heartbeat is often harmless and feels like a flutter in the heart. When the electrical impulses chronically cause the heart to beat too fast or too slow, the heart is unable to properly pump blood throughout the body.
Types of Arrhythmias
According to the National Heart, Lung and Blood Institute, there are four main types of arrhythmias.
Premature beats are the most common arrhythmia and often feel like a skipped beat. This type of arrhythmia is often harmless and may be the cause of too much exercise, caffeine or nicotine.
Supraventricular arrhythmias are fast and irregular heart rates that start in the atria of the heart. A serious form of supraventricular arrhythmias is called atrial fibrillation and is caused when electrical signals are traveling through the atria more than 300 times a minute, causing the walls to quiver instead of pump blood.
Ventricular arrhythmias begin in the ventricles of the heart and can be dangerous. Often, this type of arrhythmia is caused by a weakened heart muscle resulting from coronary heart disease or heart attack. The two main types are ventricular tachycardia and ventricular fibrillation.
Bradyarrhythmias occur when the heart rate is below 60 beats per minute. This low heart rate is not to be confused with physically fit athletes. A bradyarrhythmia associated with a serious disease or condition may be a result of blocked bundle branches delaying the electrical signal, preventing the ventricles from contracting at the same time.
