From the Guidelines
The presence of an RSR' pattern (Right Bundle Branch Block) in 2 leads of an Electrocardiogram (ECG) is significant as it indicates a conduction delay or block in the right bundle branch of the heart's electrical conduction system.
Key Criteria for RBBB
- rsR', rsR, or rSR pattern in leads V1 or V2, with the R' or r' deflection usually wider than the initial R wave 1
- S wave of greater duration than R wave or >40 ms in leads I and V6 in adults
- Normal R peak time in leads V5 and V6 but >50 ms in lead V1
Clinical Implications
This pattern can be associated with various conditions, including cardiac structural abnormalities, congenital heart disease, or acquired heart disease.
Diagnosis
A diagnosis of complete RBBB is made when the QRS duration is ≥120 ms, while incomplete RBBB is diagnosed when the QRS duration is between 110-119 ms 1. It is essential to consider the clinical context and other ECG findings when interpreting the significance of an RSR' pattern.
From the Research
Significance of RSR' Pattern in ECG
The RSR' pattern, also known as a Right Bundle Branch Block (RBBB), is a common finding in electrocardiogram (ECG) interpretations. This pattern can be observed in leads V1-V2 and may have various causes, ranging from benign non-pathological variants to severe or life-threatening heart diseases.
Possible Causes of RSR' Pattern
- The RSR' pattern can be caused by incomplete right bundle branch block, which may progress to complete right bundle branch block 2
- It can also be a normal electrophysiological variant, especially in asymptomatic and otherwise healthy individuals 3
- In some cases, the RSR' pattern can be misinterpreted as pathological after certain clinical events, such as cardiac arrest or syncope of unknown cause 3
- The pattern can be associated with severe heart diseases, such as Brugada syndrome or arrhythmogenic right ventricular dysplasia 3, 4
Diagnostic Criteria
- The RSR' pattern can be diagnosed using specific ECG criteria, including the analysis of the ST segment and r' width 5
- The pattern can be distinguished from other ECG abnormalities, such as the Brugada syndrome, using newly proposed criteria 5
- The presence of an RSR' pattern in leads V1-V2 can be evaluated using high precordial lead ECGs in conjunction with the new criteria 5
Prognostic Significance
- The prognosis of right bundle branch block in the absence of underlying cardiac disease is generally good 4
- However, the presence of an RSR' pattern in certain leads, such as lateral leads, can be associated with an increased risk of mortality in patients with known cardiac disease 6
- The fragmented QRS complex, which includes various RSR'-patterns, can be a common finding in middle-aged subjects, but it is not always associated with increased mortality 6