From the Guidelines
An RSR' pattern on an ECG is a specific QRS complex morphology that indicates right bundle branch block (RBBB), which may be a normal variant or associated with underlying cardiac conditions. This pattern is characterized by an initial R wave, followed by an S wave, and then a second R wave (called R prime or R'), and is most commonly seen in the right precordial leads (V1-V3) 1. The presence of bundle branch block on ECG, including RBBB, can be a predictor for abnormal conduction properties identified at electrophysiological studies (EPS), as noted in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Some key points to consider when evaluating an RSR' pattern on an ECG include:
- The QRS duration, which can help distinguish between complete and incomplete RBBB
- The presence of other ECG abnormalities or cardiac symptoms
- The patient's medical history and risk factors for cardiac disease
- The need for further cardiac evaluation, such as EPS, to rule out underlying pathology
In patients with syncope and bundle branch block, including RBBB, the underlying cause of syncope may be related to vasodepressor mechanisms rather than heart block-mediated bradycardia, and EPS can be used to evaluate atrioventricular conduction and identify the presence and extent of infranodal disease 1. Permanent pacing has been recommended for patients with syncope and HV intervals ≥70 ms or frank infranodal block, highlighting the importance of thorough evaluation and management of patients with RBBB and associated symptoms 1.
From the Research
RSR Pattern on ECG
The RSR pattern on an electrocardiogram (ECG) can be a benign finding or a sign of an underlying heart condition.
- The differential diagnosis of an RSR pattern in leads V1-V2 is a frequently encountered entity in clinical cardiology, and the causes may vary from benign nonpathological variants to severe or life-threatening heart diseases, such as Brugada syndrome or arrhythmogenic right ventricular dysplasia 2.
- A study found that the RSR' pattern was not associated with an increased risk of cardiovascular disease (CVD) or all-cause mortality in adults free of clinical CVD 3.
- High precordial ECG lead placement can help confirm the absence of a Brugada ECG pattern, and new criteria have been proposed to identify true Brugada pattern ECGs 4.
Investigation of RSR Pattern
The investigation of an RSR pattern in leads V1-V2 involves:
- A history and physical examination to screen for underlying cardiac disease and potential triggers 5.
- Routine investigation involves blood work and a thorough electrocardiographic examination.
- Echocardiography has a role in evaluating patients in whom structural heart disease is suspected.
- Pulmonary testing using computed tomography can be conducted if right ventricular enlargement is identified.
- Referral to an arrhythmia specialist should be considered for patients in whom this finding is due to Brugada syndrome, arrhythmogenic right ventricular dysplasia, or Wolf-Parkinson-White syndrome 5.
Interpretation of ECG
The interpretation of ECG results is crucial in determining the significance of the RSR pattern.
- A practical approach to the investigation of an RSR pattern in leads V1-V2 has been proposed, which involves a clinical and electrocardiographic algorithm to narrow the differential diagnosis 5.
- The normal pacemaker electrocardiograph can be complex and may mimic pacemaker malfunction, leading to unnecessary tests or surgery 6.