UMEM Educational Pearls

Category: Cardiology

Title: low voltage on ECG

Keywords: low voltage, electrocardiography, effusion (PubMed Search)

Posted: 6/30/2008 by Amal Mattu, MD (Updated: 8/17/2022)
Click here to contact Amal Mattu, MD

Low QRS voltage on the ECG has various definitions; here's my simple definition for low voltage...either one of the following:
     If the added QRS amplitudes (whole R wave + S wave) in leads I + II + III total < 15 mm, OR
     If the added QRS amplitudes (whole R wave + S wave) in leads V1 + V2 + V3 total < 30 mm.

The potential causes of  low QRS voltage includes pericardial effusions, pleural effusions, obesity, COPD, infiltrative cardiac diseases (e.g. sarcoid, amyloid), end-stage cardiomyopathies, severe hypothyroidism.

If the patient has NEW low voltage compared to an old ECG, the only real possibilities are pericardial effusion, pleural effusion, and severe hypothyroidism (e.g. myxedema).