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Common Myths and Fallacies in ECG (1)

Prof. Wang, Tzong-LuenMD, PhD, JM, FESC, FACC

Shin-Kong Wu Ho-Su Memorial Hospital

2010.8.23. SKH2010/9/23 2

PrefaceAll ECGs are classified as two kinds, that is, narrow QRS and wide QRS complexes. Wide QRS complexes are so-called “BBB”.

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Normal ECG

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High Speed Midline Conduction

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Myth and Fallacy #1 All wide QRS complexes originate from ventricle, whereas narrow ones from supra-ventricle. Wide QRS complexes: RBBB and LBBB VPC and VT Ventricular pacing WPW

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RBBB

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LBBB

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VT

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Ventricular Pacing

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WPW Syndrome

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WPW Syndrome

Fusion Beat 2010/9/23 16

VPC or APC

Compensatory Pause

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Myth and Fallacy #2RSR’ (or rsR’) is characteristic of RBBB.

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VT(RBBB)

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VT(LBBB)

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QRS Axis

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RBBB

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Myth and Fallacy #3 Which one of the following has the lowest conduction velocity?

Atrial myocardium AV node His bundle Purkinje fiber Ventricular myocardium

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Normal ECG

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WPW with Atrial fibrillation

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Myth and Fallacy #4 Which one of the following criteria is the best for diagnosing wide QRS complex rhythm?

QRS complexes in all 12 leads should be wide. QRS complexes in at least more than half leads should be wide. QRS complexes in at least one lead should be wide.

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Wide or Narrow? VT or SVT?

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Myth and Fallacy #5 The electrical waves resulting from atrialrepolarization are buried under QRS complexes.

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The Truth is …The electrical waves resulting from atrialrepolarization are disclosed in PR segment. So PR depression or elevation can be reasonably expected. TP segment instead of PR segment should be considered as the baseline for identifying ST segment deviation.

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Pericarditis with PR Depression

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Inferior MI with PR Elevation RA Myocardial Infarct