Changing P wave polarity. Intermittent posterior internodal conduction.

Area of Science:

• Cardiology
• Electrophysiology

Background:

• Electrocardiogram (ECG) interpretation is crucial for diagnosing cardiac conditions.
• Atrial activation sequences can vary and influence ECG findings.

Observation:

• A patient presenting with chest pain exhibited spontaneous P-wave polarity changes on their resting ECG.
• Heart rate remained constant during these observed polarity shifts.

Findings:

• Intracardiac and His bundle electrograms revealed an activation sequence from the high to low right atrium.
• Both positive and negative P waves were recorded in lead aVR.
• A decreased P-His interval correlated with positive P waves in lead aVR, indicating selective conduction.

Implications:

• This suggests selective conduction via the posterior internodal pathway.
• Understanding atypical atrial activation can refine diagnostic capabilities for complex cardiac presentations.
• Further research into internodal pathway conduction may reveal new insights into arrhythmias.