An electrocardiogram (ECG), also known as an EKG, is a painless test that records the heart’s electrical activity. It assesses heart health, particularly when symptoms like chest pain, dizziness, or palpitations occur. An ECG helps providers understand the heart’s rate, rhythm, and electrical impulse timing. An “abnormal” reading indicates a deviation from typical patterns, suggesting further investigation is needed to determine its cause and significance.
What an Electrocardiogram Measures
An ECG detects electrical changes as the heart muscle depolarizes and repolarizes with each beat. Electrodes, small sticky patches, are placed on the chest, arms, and legs. These connect to an ECG machine, which records and displays electrical signals as a wavy line. This graphical representation details the heart’s electrical function.
The ECG tracing consists of distinct waves and segments, each representing a specific phase of the heart’s electrical cycle. The P wave signifies electrical activity causing the atria (upper chambers) to contract. The QRS complex represents electrical activity leading to ventricular (lower chamber) contraction, pumping blood to the body. The T wave indicates ventricular repolarization, or electrical recovery, as they relax and refill. Analyzing these waves’ rate, rhythm, and morphology provides insights into the heart’s electrical conduction.
Common Abnormalities Detected
ECG readings reveal deviations from normal electrical patterns, categorized by issues with rate, rhythm, conduction, or waveform morphology. Rate abnormalities include tachycardia (over 100 beats per minute) or bradycardia (under 60 beats per minute).
Rhythm abnormalities, or arrhythmias, involve irregular heartbeats. Examples include atrial fibrillation (chaotic electrical activity in the atria) and premature beats (extra heartbeats from atria or ventricles). Conduction abnormalities refer to problems with the heart’s electrical pathways, such as heart blocks, where signals are partially or completely interrupted between atria and ventricles.
Waveform changes involve alterations in the shape, size, or duration of P, QRS, or T waves. ST segment elevation or depression can signal reduced blood flow to the heart muscle. Inverted T waves may indicate ischemia or electrolyte imbalances. A prolonged QT interval, representing ventricular contraction and relaxation time, can indicate a risk for certain arrhythmias.
Conditions Associated with Abnormal ECG Readings
An abnormal ECG often points to specific medical conditions affecting the heart. Changes in the ST segment or T waves can signal a heart attack (myocardial infarction) or ischemia. Arrhythmias, such as atrial fibrillation or ventricular tachycardia, can indicate problems with the heart’s electrical system, potentially increasing stroke risk or other complications.
Structural heart problems, like enlarged chambers or thickened walls (hypertrophy), may be suggested by abnormal ECG patterns. These changes indicate the heart might be working harder to pump blood. Electrolyte imbalances, particularly in potassium or calcium, can significantly affect the heart’s electrical signals, manifesting as abnormal ECG readings.
Heart inflammation, such as pericarditis (inflammation of the sac around the heart) or myocarditis (inflammation of the heart muscle), can alter ECG patterns. Certain medications can impact heart electrical activity, leading to abnormal ECG results as a side effect. Non-cardiac conditions like lung disease or thyroid issues can also influence ECG readings.
What Happens After an Abnormal ECG
An abnormal ECG result indicates the need for further evaluation. The first step involves a consultation with a healthcare provider to interpret findings within the individual’s health, history, and symptoms. The provider will discuss the abnormalities and determine the next course of action.
Further diagnostic tests are recommended for a comprehensive understanding of the heart’s condition. These may include an echocardiogram (ultrasound to visualize heart structure and function) or a Holter monitor (portable device recording heart activity over 24-48 hours to detect intermittent rhythm issues). A stress test might assess heart function during physical exertion. Blood tests can check for heart damage markers or electrolyte imbalances. Depending on findings, a cardiologist referral may be necessary for evaluation and management.