Low QRS Voltage

Low QRS voltage on the electrocardiogram (ECG) refers to reduced amplitude of the QRS complexes. This finding may be seen in all leads (generalized low voltage) or limited to the precordial or limb leads (localized low voltage).

Electrocardiographic Criteria

• QRS amplitude < 5 mm in all limb leads
• QRS amplitude < 10 mm in all precordial leads
• Sokolow-Lyon index: S wave in V1 + R wave in V5 or V6 ≤ 15 mm

Common causes

1. Pericardial or pleural disease:
   • Pericardial effusion: fluid in the pericardial space reduces electrical conduction.
   • Cardiac tamponade: may coexist with electrical alternans.
   • Massive pleural effusions.
2. Lung disease:
   • Chronic obstructive pulmonary disease (COPD): hyperinflated lungs increase resistance to electrical flow.
3. Infiltrative or fibrosing disease:
   • Cardiac amyloidosis: amyloid deposition in the myocardium reduces voltage.
   • Sarcoidosis, myocardial fibrosis.
4. Obesity or generalized edema:
   • Layers of adipose tissue or fluid reduce electrical conduction.
5. Hypothyroidism:
   • Related to reduced myocardial metabolism and pericardial fluid accumulation.
6. Cardiomyopathies:
   • Severe dilated cardiomyopathy, in which reduced contractility and cardiac dilation can cause low voltage.
7. Other:
   • Post-infarction with extensive fibrosis.
   • Use of certain medications or misplaced electrodes.

ECG in Low QRS Voltage

Low QRS voltage. Low-voltage complexes are defined by a QRS amplitude of less than 5 mm in all frontal plane leads or less than 10 mm in all horizontal plane leads.

Related Topics

• Cardiac Tamponade