I have everything I need. Now let me carefully analyze the ECG image and compare it against LBBB criteria.
ECG Analysis: Is the LBBB Diagnosis Correct?
Short answer: The LBBB diagnosis is likely INCORRECT — this ECG is more consistent with Right Bundle Branch Block (RBBB).
Here's why:
What the ECG Actually Shows
Looking carefully at the image:
| Lead | Observation |
|---|
| V1 | Appears to show an rSR' (M-shaped / rabbit-ear) pattern — a tall late R' wave |
| V4–V6 / lateral leads | Show wide S waves (slurred, broad terminal S) |
| QRS | Wide (≥120 ms) |
| ST-T changes | Discordant (as expected with BBB) |
RBBB vs LBBB — The Key Distinction
| Feature | RBBB | LBBB |
|---|
| V1 pattern | rSR' — M-shaped (tall late R') ✅ | Broad, deep QS or rS (W-shaped) |
| V6 pattern | Wide, slurred S wave ✅ | Broad, tall R (M-shaped, no S) |
| Septal Q waves | Preserved | Absent |
| Mnemonic | MaRRoW (M in V1, W in V6) | WiLLiaM (W in V1, M in V6) |
The classic mnemonic:
- LBBB = WiLLiaM → W-shape in V1, M-shape in V6
- RBBB = MaRRoW → M-shape in V1, W-shape in V6
From the ECG image, V1 shows a prominent late positive deflection (rSR' = M-shape), and the lateral leads show terminal S waves — this is the pattern of RBBB, not LBBB.
Why the Listed Diagnosis May Be Wrong
The report states:
- ✅ Wide QRS — correct, present in both BBBs
- ❌ "Deep, wide S waves in V1" — in LBBB, V1 shows QS or rS (not deep S specifically). Deep S in V1 with rSR' actually supports RBBB
- ❌ "Broad notched M-shaped R waves in V5–V6, I, aVL" — M-shaped in lateral leads = LBBB feature, but this needs to actually be present in the tracing
- The mnemonic given at the bottom (V1 = W-shaped, V6 = M-shaped) is correct for LBBB — but if V1 actually shows an M-shape (rSR'), then the ECG is RBBB
Conclusion
Your suspicion is correct — the diagnosis appears to be false.
Based on the visible ECG morphology (M-shape/rSR' in V1 with terminal S in lateral leads), this ECG is most consistent with Right Bundle Branch Block (RBBB), not LBBB.
The listed features (M-shape in V6/lateral leads, W in V1) would indeed define LBBB — but the actual tracing does not match those features.
⚠️ ECG interpretation requires clear lead labeling and quality tracings. A formal over-read by a cardiologist is always recommended for clinical decisions. — Harrison's Principles of Internal Medicine 22E, Bundle Branch Blocks section