From the Guidelines
A right bundle branch block (RBBB) with right axis deviation and possible right ventricular hypertrophy often suggests a pulmonary component, and therefore, it is likely that there is a pulmonary component to these ECG findings. These electrical conduction abnormalities frequently occur in conditions that increase pressure in the pulmonary circulation, causing strain on the right side of the heart. Common pulmonary causes include pulmonary hypertension, chronic obstructive pulmonary disease (COPD), pulmonary embolism, or congenital heart defects 1. The electrocardiographic findings of right axis deviation and prominent anterior forces in the right precordial leads are consistent with right ventricular hypertrophy (RVH), which is often associated with pulmonary disease 1.
To confirm a pulmonary component, additional testing is recommended, including:
- Echocardiography to assess right ventricular size and function
- Pulmonary function tests to evaluate lung capacity
- Possibly a CT pulmonary angiogram if pulmonary embolism is suspected
- Blood tests for BNP (brain natriuretic peptide) levels may also help determine cardiac strain 1. The physiological basis for these ECG findings is that increased pulmonary vascular resistance leads to right ventricular pressure overload, causing myocardial hypertrophy and altered electrical conduction patterns through the right bundle branch.
It is essential to note that the sensitivity of electrocardiographic criteria for RVH is generally low, but some criteria have high specificity and can be used to advantage in diagnostic schemes 1. The use of ancillary clinical information plays a greater role in the appropriate use of the ECG for the purpose of recognizing RVH than it does in the case of LVH or the atrial abnormalities 1. Therefore, a comprehensive evaluation, including clinical history, physical examination, and additional diagnostic testing, is necessary to determine the presence and severity of a pulmonary component in patients with RBBB and right axis deviation.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Right Bundle Branch Block and Right Axis Deviation
- Right bundle branch block (RBBB) with right axis deviation may be associated with right ventricular hypertrophy, as seen in arrhythmogenic right ventricular cardiomyopathy (ARVC) 2.
- A study found that RBBB ventricular tachycardia in ARVC more commonly originates from the right ventricle, with criteria for identifying the chamber of origin including precordial QRS transition and frontal plane axis 2.
Possible Pulmonary Component
- There is no direct evidence in the provided studies to suggest a pulmonary component in RBBB with right axis deviation.
- However, a study on idiopathic RBBB found impaired myocardial shortening and mechanical dispersion in both the left and right ventricles, which may be related to underlying cardiac disease or other factors 3.
Electrocardiographic Patterns and Prognosis
- Dissimilar electrocardiographic patterns associated with RBBB have been described, including changing axis deviation and intermittent RBBB 4, 5.
- The prognosis of RBBB in the absence of underlying cardiac disease is generally good, but may be poor in cases with coronary artery disease or other underlying conditions 4.