An electrocardiogram (ECG or EKG) is a non-invasive medical test that records the electrical signals generated by the heart. It helps healthcare professionals assess heart health and identify issues. The ECG machine detects these impulses through electrodes on the skin, translating them into a graphical representation of cardiac activity.
Understanding ECG Readings
A normal ECG tracing displays a predictable pattern of waves, reflecting electrical activity. This pattern provides information about the heart’s rate, rhythm, and the timing of electrical impulses. The basic components of an ECG include the P wave, the QRS complex, and the T wave.
The P wave signifies depolarization of the atria (upper chambers). The QRS complex represents ventricular depolarization. The T wave illustrates ventricular repolarization. Deviations from this wave pattern can indicate various underlying conditions.
Cardiac Conditions
Abnormal ECG readings stem from heart issues. These include rhythm disturbances and structural problems.
Arrhythmias are a common cause of abnormal ECG patterns. Conditions like atrial fibrillation (irregular atrial beat), bradycardia (slow heart rate), and tachycardia (fast heart rate) are distinctively shown. Coronary artery disease (reduced blood flow) can alter ECG readings, appearing as changes in ST segment or T waves, signaling ischemia or a heart attack.
Structural heart problems, such as an enlarged heart (cardiomyopathy) or damage from a previous heart attack, can lead to abnormal ECG results. Electrical conduction issues, like heart blocks or bundle branch blocks (delayed or interrupted signals), also produce specific QRS complex changes.
Non-Cardiac Factors
Abnormal ECG readings are not always due to heart disease; other factors can influence heart electrical activity. These non-cardiac influences are important to consider.
Electrolyte imbalances (potassium, calcium, magnesium) significantly affect heart electrical signals. Both high and low potassium levels can cause distinct changes in the T wave and QRS complex, while calcium imbalances primarily affect the QT interval. Certain medications, including antidepressants and anti-arrhythmics, can alter ECG readings as a side effect.
Lung conditions, such as COPD or pulmonary embolism, can indirectly impact the heart and lead to ECG changes. Other medical conditions, like thyroid disorders, can also influence heart rate and rhythm, resulting in an abnormal ECG. Occasionally, an “abnormal” reading may arise from technical issues, such as incorrect electrode placement or electrical interference, rather than a physiological problem.
What Happens After an Abnormal ECG
An abnormal ECG result does not automatically indicate a serious heart condition. Further evaluation is often necessary to determine the cause and significance.
Next steps involve additional diagnostic tests to clarify heart health. These may include a repeat ECG, blood tests (for markers or electrolyte levels), or an echocardiogram (ultrasound for heart structure and function). A stress test (monitoring heart activity during exercise) or a Holter monitor (records heart rhythms) might also be recommended. Discuss ECG results with a healthcare professional, such as a cardiologist, for interpretation and guidance on follow-up or treatment plans.