LBBB: Negative Concordant Precordial Pattern

Report:

Sinus rhythm

PR interval 0.20”

Left atrial abnormality

Normal axis

Left bundle branch block

Comment:

History of infarction and marked cardiomegaly are clues as to why there is a concordant precordial QS pattern. This example has normal axis: it is chosen to obviate a third cause for QS in V5-6 - a frontal plane right or left axis deviation, which predisposes to dramatic changes in these leads with slight vertical electrode displacement. Approximately 50% of patients with LBBB have normal axis.

Lead V7 shows an R wave in this patient with cardiomegaly (Fig 17a).

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