Normal Sinus Rhythm with RSR' Pattern in V1 (Normal Variant)
This ECG most likely represents normal sinus rhythm with a normal variant RSR' pattern in V1, not incomplete right bundle branch block (RBBB), given the normal QRS duration of 88 ms. The borderline PR interval of 217 ms warrants attention but is likely a benign finding in this young, otherwise healthy woman.
ECG Analysis
QRS Duration and RSR' Pattern
The key diagnostic feature here is the QRS duration of 88 ms, which is well within normal limits (normal <110 ms in adults). According to AHA/ACCF/HRS guidelines, incomplete RBBB requires a QRS duration between 110-120 ms in adults 1. Since this patient's QRS is only 88 ms, she does not meet criteria for incomplete RBBB.
The RSR' pattern in V1 with a normal QRS duration is explicitly recognized as a normal variant in the guidelines 1. The guidelines specifically state: "In children, an rsr pattern in V1 and V2 with a normal QRS duration is a normal variant" and note that "The ECG pattern of incomplete RBBB may be present in the absence of heart disease, particularly when the lead V1 is recorded higher than or to the right of normal position" 1.
PR Interval Consideration
The PR interval of 217 ms is at the upper limit of normal (normal range: 120-200 ms). While technically prolonged, this degree of first-degree AV block in a young, asymptomatic woman (aside from palpitations) is generally benign and does not require specific intervention. The palpitations are unlikely related to this mild PR prolongation.
Other Normal Findings
- Heart rate: 69 bpm (normal sinus rhythm)
- QTc: 407 ms (normal, <450 ms in women)
- All other intervals are within normal limits
Clinical Significance and Management
Regarding the Palpitations
The palpitations in this patient are not explained by the ECG findings, as the ECG shows normal sinus rhythm at the time of recording. The RSR' pattern is a benign finding and does not cause palpitations. Consider:
- Ambulatory monitoring (Holter or event monitor) to capture the rhythm during symptomatic episodes
- Evaluate for paroxysmal arrhythmias (premature atrial contractions, premature ventricular contractions, paroxysmal supraventricular tachycardia)
- Screen for non-cardiac causes: anxiety, caffeine, thyroid dysfunction, anemia
Important Caveats
- The RSR' pattern can occasionally represent early or subtle structural heart disease (e.g., atrial septal defect, right ventricular volume overload), though this is uncommon in young adults with normal QRS duration
- If palpitations persist or worsen, consider echocardiography to exclude structural abnormalities
- The mild PR prolongation does not require pacing or specific treatment unless it progresses significantly or becomes symptomatic (which is rare at this degree)
Follow-up Recommendations
- Symptom-rhythm correlation is essential—capture the ECG during palpitations
- Reassurance that the baseline ECG findings are benign
- No activity restrictions needed based on these ECG findings
- Routine follow-up unless symptoms worsen or new concerning features develop