ECG Case 047

Middle-aged patient presenting with palpitations. Describe the ECG

TOP 100 ECG QUIZ LITFL 047

Describe and interpret this ECG

ECG ANSWER and INTERPRETATION

This is another example of ventricular tachycardia, this time with a dominant S wave in V1/V2 and therefore a LBBB morphology (compare this with ECG 046).

Regular broad complex tachycardia at ~ 160 bpm.

Features of VT in V1:

  • Initial R wave > 30 ms wide, RS interval > 70 ms (Brugada sign)
  • Notching/slurring of the downslope of the S wave in V1/V2 (Josephson sign).

 Features of VT in V6:

  • Dominant S wave in V6; qR wave; absence of typical LBBB morphology
  • Abnormal axis with positive aVR, although does not quite meet criteria for northwest axis.

NB. Note that a positive Brugada sign only requires an RS interval of >60 ms when LBBB morphology is present, compared to >100 ms when RBBB morphology is present.

Brugada-criteria-LBBB-VT-V1-2 Wellens
Image reproduced from Wellens (2001). See references for link.

Dominant S Wave in V1 or V2 (LBBB Morphology)

Lead V1 or V2

ECG VT V2 S wave notch Josephson sign 700

Lead V6

ECG VT V6 qR wave LBBB morphology 700

These features are very different to the expected pattern in LBBB, which has:

  • Dominant S wave in V1, but with an R/S interval < 70 ms and minimal initial R wave.
  • Dominant R wave in V6 (often slurred).
ECG LBBB WILLIAM Morrow

CLINICAL PEARLS

Tips for Spotting VT when LBBB morphology present

[NB. LBBB morphology = QRS > 120ms with dominant S wave in V1]

Suspect VT in any patient with a regular broad complex tachycardia (esp if > 160 ms wide).

Look at aVR
  • Positive QRS complex?
  • Leads I and aVF negative?
  • If yes to both -> northwest axis is present -> probable VT.
Look at V1
  • Initial R wave > 30 ms? –> probable VT.
  • Notching of the S wave (Josephson’s sign)? –> probable VT.
  • RS interval > 70 ms (Brugada’s sign)? –> probable VT.
  • None of the above –> possible SVT with LBBB.
Look at V6
  • Dominant S wave (R/S ratio < 1)? -> probable VT.
  • Dominant R wave (R/S ratio > 1)?-> possible SVT with LBBB.

If still uncertain, scrutinise the ECG for:

If still uncertain…review the ECG for:
ECG VT AV dissociation

AV dissociation: superimposed P waves at a different rate to the QRS complexes


ECG VT Fusion beat capture beat

The first of the narrower complexes is a fusion beat, the next two are capture beats.


TOP 100 ECG SERIES


Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

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