A low voltage ECG refers to an electrocardiogram in which the amplitude of the QRS complexes is reduced. This is typically defined as peak-to-peak amplitude in the limb leads being less than 5 mm, or less than 10 mm in the precordial leads. Low voltage on an ECG can be a significant finding, associated with several conditions:
- Pericardial Effusion: Fluid in the pericardial space can physically separate the heart from the ECG electrodes, diminishing the signal.
- Cardiomyopathy: Diseases that infiltrate or damage the myocardium can decrease the amplitude of the electrical signals.
- Myxedema (Severe Hypothyroidism): This condition can lead to an accumulation of mucopolysaccharides in the skin and other tissues, which may insulate the electrical activity.
- Obesity and Emphysema: Both conditions can increase the distance between the heart and the chest wall, reducing ECG voltage.
- Amyloidosis: Infiltration of the heart by amyloid can dampen electrical signals.
- Pleural Effusion: Similarly to pericardial effusion, a large amount of fluid in the pleural space can also reduce ECG voltage.
When interpreting a low voltage ECG, it’s essential to consider the clinical context and any underlying conditions that might explain the finding. Further diagnostic testing, such as echocardiography or MRI, may be warranted to explore the cause of low ECG voltage.