What is a right axis deviation on an electrocardiogram (ECG)?

Right Axis Deviation on an ECG

Right axis deviation (RAD) on an ECG is defined as a mean frontal plane QRS axis of greater than +90° in adults, representing an abnormal electrical activation pattern of the ventricles that is often associated with right ventricular hypertrophy, pulmonary hypertension, or other cardiopulmonary conditions. 1

Definition and Normal Values

• Normal QRS axis in adults: +30° to +90° 1
• Right axis deviation: >+90° 1
• Age-specific normal ranges are important to consider:
  • Neonates: +30° to +190°
  • Children 1-5 years: +10° to +110°
  • Children 5-8 years: up to +140°
  • Children 8-16 years: up to +120°
  • Adults: +30° to +90° 1

Clinical Significance and Associated Conditions

Right axis deviation is frequently associated with:

• Right ventricular hypertrophy (RVH) 1, 2
• Pulmonary hypertension 1
• Chronic lung disease 1
• Left posterior fascicular block 1
• Congenital heart defects 1
• Extensive myocardial ischemia (in acute settings) 3

In the context of biventricular hypertrophy, right axis deviation in the presence of ECG criteria for left ventricular hypertrophy (LVH) and tall biphasic R/S complexes in several leads can suggest the presence of both RVH and LVH. 4

Diagnostic Criteria for Right Axis Deviation

• QRS axis >+90° in adults 1
• In some studies, extreme right axis deviation is defined as a shift in QRS axis between +180° and +270° 3
• Common ECG findings that may accompany RAD:
  • R/S ratio in lead V5 or V6 ≤1
  • S in V5 or V6 ≥7 mm
  • Right atrial abnormality (P pulmonale) 2

Clinical Evaluation Algorithm

When right axis deviation is detected on ECG:

1. Review for other ECG abnormalities:

   • Look for evidence of right ventricular hypertrophy
   • Check for right atrial abnormality
   • Assess for conduction abnormalities

2. Consider echocardiography to evaluate:

   • Ventricular size and function
   • Presence of congenital heart defects
   • Evidence of pulmonary hypertension 1

3. Additional testing based on clinical suspicion:

   • Pulmonary function tests if lung disease suspected
   • CT pulmonary angiography to rule out pulmonary embolism
   • Right heart catheterization for definitive diagnosis of pulmonary hypertension 1

Clinical Pitfalls and Caveats

• ECG has limited sensitivity (73%) for detecting pulmonary hypertension, so a normal ECG does not rule out significant disease 1
• RAD may be a normal variant in some individuals, particularly in children and young adults 1
• Body position, lead placement, and body habitus can influence QRS axis determination 1
• In the setting of acute myocardial infarction, new-onset extreme right axis deviation may indicate extensive myocardial ischemia and is associated with higher risk of complications 3
• The presence of right bundle branch block with right axis deviation in apparently healthy men has not been associated with adverse long-term prognosis in some studies 5

Management Implications

Management should focus on identifying and treating the underlying cause:

• For pulmonary hypertension: consider pulmonary vasodilators and management of right heart failure 1
• For structural heart disease: regular echocardiographic monitoring is recommended 1
• For chronic lung disease: optimize management of the underlying condition 1

Regular clinical assessment is necessary to monitor for symptoms of right heart failure and to optimize management of underlying conditions 1.