Low Voltage ECG

The low-voltage electrocardiogram (ECG) is connected with various cardiac as well as noncardiac problems in addition to lead cable reversals and also various other electronic equipment issues.

Note: In the absence of a pathological cause, low-voltage QRS in the ECG can be a typical variant, it can be caused by electrical malfunction of the recorder or cable links, or it can be related to electrode misplacement as well as cable transposition

Diagnostic criteria

The QRS is claimed to be low voltage when the amplitudes of all the QRS complexes:

1. In the limb leads are < 5 mm; or

2. In the precordial leads are < 10 mm

Voltage can be low when there is increased tissue, loss of myocardial tissue (e.g. myocardial infarction), air or fluid between the heart and the electrodes (e.g. effusions, emphysemia) or with infiltration of cardiac tissues (e.g. hemochromatosis, amyloid)

The situations where  Low voltage may be present are:

  1. Obesity
  2. Chronic obstructive pulmonary disease, or COPD
  3. Pericardial effusion
  4. Severe hypothyroidism
  5. Subcutaneous emphysema
  6. Massive myocardial damage/infarction
  7. Infiltrative/restrictive diseases such as amyloid cardiomyopathy

Note: The indicator/ Standardisation should be set to 10 mm amplitude. If the standardisation indicated at the left of the ECG is turned down accidentally, the voltage will be falsely low (pseudo low voltage).

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