Hidden P waves

P waves can be hidden if they occur during the T wave. This can occur when the rate is fast (e.g. Sinus Tachycardia) or with conduction blocks. Lewis leads can help to uncover the P waves.

See also: P wave

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ECG Library (3)

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In the ECGquest archives, this ECG has been tagged with: - 12-Lead Hidden P waves Sinus tachycardia Dr Smith's ECG Blog CC BY-NC
Regular, steady, and fast at 170 (wide or narrow?), hypoxic, crackles in lungs, B-lines, unconscious

This ECG is from a man in his 60s who was found unconscious and hypoxic.

This ECG shows sinus tachycardia with P waves partially hidden in the T waves before them.

In the ECGquest archives, this ECG has been tagged with: - Chest pain Dyspnoea 12-Lead Absent P waves Bradycardia Hidden P waves Irregular Narrow QRS Normal Axis Short PR Change in rhythm Junctional escape Multiple rhythms Sinus arrhythmia Sinus bradycardia Dr Smith's ECG Blog CC BY-NC
What is the Rhythm?

This ECG is from a young man who presented shortly after a 45 min episode of palpitations, shortness of breath, chest pressure and presyncope. He was an athlete.

This ECG shows marked sinus bradycardia with AV dissociation by default (not AV block) with junctional escape beats.

In the ECGquest archives, this ECG has been tagged with: - Fatigue Hypotension Weakness 12-Lead Serial 12-lead Hidden P waves Narrow QRS Regular Tachycardia Sinus tachycardia Dr Smith's ECG Blog CC BY-NC
Atrial fibrillation with RVR: use POCUS to assess volume; then sinus vs. SVT: use of Lewis leads. Repeat after IVF