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P waves morphology
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P Wave Morphology Analysis - 12-Lead ECG
This ECG (from Father Muller Hospital, settings: 25 mm/s, 10 mm/mV, filtered 0.67-25 Hz AC50) carries a machine interpretation of "Prolonged QT Interval." However, based on the detailed visual analysis, the dominant finding relates to the P waves - and they are not normal sinus P waves.
Key Finding: Absent Normal P Waves - Atrial Flutter Pattern
The "P waves" in this tracing are actually flutter (F) waves, not true P waves:
| Lead | Morphology |
|---|---|
| Lead I | Flat / nearly isoelectric - no discrete P wave |
| Lead II | Sawtooth negative deflections - classic flutter waves |
| Lead III | Inverted / sawtooth appearance |
| aVR | Upright flutter waves (mirror of II) |
| aVL | Inverted, sawtooth |
| aVF | Inverted / negative sawtooth - consistent with II and III |
| V1 | Upright, sharp, spike-like flutter waves - most prominent lead for flutter |
| V2 | Biphasic, transitioning positive-to-negative |
| V3-V6 | Progressively less distinct, smaller amplitude flutter waves |
Interpretation
Rhythm: Atrial Flutter (most likely typical, counter-clockwise/Type I)
- Sawtooth F waves are best seen in the inferior leads (II, III, aVF) - they are negative/inverted in the classic "typical atrial flutter" pattern
- V1 shows upright, sharp flutter waves at approximately 250-300 bpm atrial rate
- No discrete, rounded, upright P waves are present in leads where sinus P waves would normally be expected (I, II, aVF)
- The ventricular rate appears slower than the atrial rate, consistent with a degree of AV block (2:1 or variable) - a hallmark of atrial flutter
Why This Matters vs. Normal P Waves
| Feature | Normal Sinus P Wave | Flutter F Waves (this ECG) |
|---|---|---|
| Shape | Rounded, smooth | Sawtooth, sharp |
| Polarity in II | Upright (+) | Inverted (-) in typical flutter |
| Polarity in V1 | Biphasic or low upright | Prominent upright spike |
| Rate | 60-100 bpm | ~250-300 bpm (atrial) |
| Baseline | Returns to isoelectric | Never returns to isoelectric |
| PR interval | Fixed, measurable | Not applicable |
Summary
The P wave morphology on this ECG is abnormal - there are no true sinus P waves. Instead, there are continuous sawtooth atrial flutter waves, most clearly visible in leads II, III, aVF (inverted sawtooth) and V1 (upright sharp spikes). The machine-reported "prolonged QT" likely reflects difficulty in identifying T wave endpoints due to the flutter wave interference. The primary diagnosis is Atrial Flutter.
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