From the Guidelines
Low voltage limb leads on an electrocardiogram (ECG) are most commonly caused by conditions such as obesity, emphysema, pericardial effusion, amyloidosis, and other factors that reduce electrical signal transmission, as indicated by the European Society of Cardiology guidelines 1.
Causes of Low Voltage Limb Leads
The causes of low voltage limb leads can be categorized into several groups, including:
- Conditions that increase the distance between the heart and recording electrodes, such as obesity and emphysema
- Conditions that dampen electrical signals, such as pericardial effusion
- Conditions that impair electrical conduction, such as infiltrative cardiomyopathies like amyloidosis
- Other potential causes, including pleural effusion, pneumothorax, anasarca, and myocardial infarction with extensive scarring
Clinical Implications
When evaluating low voltage limb leads, it is essential to consider the patient's clinical context, including body habitus, respiratory status, and any symptoms of cardiac or thyroid disease, as this finding may indicate serious underlying pathology requiring further investigation 1. The European Society of Cardiology guidelines recommend echocardiography, cardiac magnetic resonance (CMR), and chest X-ray as initial diagnostic steps for patients with low QRS voltage, and further imaging and endomyocardial biopsy may be considered for amyloidosis 1.
Diagnostic Approach
The diagnostic approach to low voltage limb leads should involve a comprehensive evaluation of the patient's clinical presentation, medical history, and diagnostic test results, including ECG, echocardiography, and laboratory tests, to determine the underlying cause and guide appropriate management, as recommended by the American Heart Association and European Society of Cardiology guidelines 1.
From the Research
Causes of Low Voltage Limb Leads
- Low voltage in the limb leads can be caused by various conditions, including those that cause diffuse low voltage, as seen in 51 out of 100 patients with voltage discordant ECGs 2.
- Dilated cardiomyopathies are a common cause of low voltage isolated to the limb leads, with 63% of patients without associated conditions having dilated ventricles and an average ejection fraction of 33% 2.
- Chronic obstructive pulmonary disease (COPD) can also cause low voltage in the limb leads, as well as other ECG abnormalities such as a rightward P-wave axis and a rightward QRS axis 3.
- Pericardial effusion, which can occur in patients with acute myocardial infarction, can cause low voltage on the ECG, although it is not a specific complication of pericardial effusion 4.
- Lead misplacement, such as exchanging the right arm and right leg leads, can create a unique pattern of diffuse low voltage in the limb leads 5.
- Pericardial effusion, which can be caused by various conditions including acute myocardial infarction, cardiac surgery, and neoplastic disease, can also cause low voltage on the ECG 6.