From the Guidelines
Right axis deviation (RAD) is most commonly caused by right ventricular hypertrophy, which can be due to various underlying conditions such as pulmonary hypertension, chronic lung disease, or congenital heart defects, as supported by the most recent and highest quality study 1.
Causes of Right Axis Deviation
The causes of RAD can be diverse and include:
- Right ventricular hypertrophy (RVH) due to conditions like pulmonary hypertension or chronic lung disease
- Right bundle branch block
- Lateral wall myocardial infarction
- Pulmonary embolism
- Congenital heart defects
Diagnostic Approach
When evaluating a patient with RAD, it's essential to consider their clinical context, including symptoms like shortness of breath, chest pain, or palpitations. Further diagnostic testing may include:
- Echocardiography to assess right ventricular function and rule out other cardiac abnormalities
- Chest X-ray to evaluate lung fields and cardiac silhouette
- Pulmonary function tests to assess lung function and detect any underlying respiratory disease
Treatment
Treatment is directed at the underlying condition rather than the ECG finding itself. For example:
- If RAD is due to pulmonary hypertension, medications like sildenafil or bosentan might be prescribed
- If RAD is due to pulmonary embolism, anticoagulation would be the treatment of choice
- If RAD is due to a congenital heart defect, surgical intervention may be necessary
Clinical Significance
The significance of RAD varies widely based on the patient's overall clinical picture, so it should always be interpreted in context rather than as an isolated finding. As noted in 1, the ECG has insufficient sensitivity and specificity to be a screening tool for detecting significant pulmonary hypertension, but it can provide supportive evidence of RV hypertrophy and strain. Similarly, 1 highlights the importance of considering clinical context when interpreting ECG findings, including RAD.
From the Research
Causes of Right Axis Deviation (RAD)
- Right axis deviation can be caused by various conditions, including spontaneous pneumothorax, as seen in a case report where a 23-year-old male patient presented with sudden-onset chest pain and shortness of breath, and electrocardiogram showed right axis deviation 2.
- Tetralogy of Fallot, a congenital heart defect, can also cause right axis deviation, as well as large R waves in the anterior precordial leads and large S waves in the lateral precordial leads 3.
- Right axis deviation can be a criterion for echocardiographic evaluation, and it is sometimes used to screen for disqualifying cardiac defects in aircrew candidates, although a cost-benefit analysis has shown that it may not be cost-effective to use 2D-echocardiography to screen candidates based on a finding of right axis deviation of +95 degrees or greater on electrocardiogram 4.
Associated Conditions
- Spontaneous pneumothorax can present with various electrocardiographic findings, including axis deviation, bundle branch block, and T wave inversion 2.
- Tetralogy of Fallot can cause extreme deviation of the frontal QRS axis, which can persist into adulthood 3.
- Right axis deviation can be associated with other cardiac conditions, such as atrial septal defect, although the cost-effectiveness of using echocardiography to screen for these conditions is debated 4.