What QRS duration defines a wide complex in bundle branch blocks?

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Multiple Choice

What QRS duration defines a wide complex in bundle branch blocks?

A wide QRS complex is defined by a duration of 120 milliseconds or more. Normal QRS duration is generally up to about 100 milliseconds, with some sources allowing a small extension to around 110 ms. In bundle branch blocks, ventricular activation is delayed due to impaired conduction through one of the intraventricular pathways, so the depolarization spreads more slowly and the QRS becomes prolonged. Measuring from the onset of the Q (or R) wave to the end of the S wave, a duration of 120 ms or longer indicates a wide complex typical of bundle branch block. Durations such as 60, 80, or 100 ms are within normal limits and do not define a wide complex.

A wide QRS complex is defined by a duration of 120 milliseconds or more. Normal QRS duration is generally up to about 100 milliseconds, with some sources allowing a small extension to around 110 ms. In bundle branch blocks, ventricular activation is delayed due to impaired conduction through one of the intraventricular pathways, so the depolarization spreads more slowly and the QRS becomes prolonged. Measuring from the onset of the Q (or R) wave to the end of the S wave, a duration of 120 ms or longer indicates a wide complex typical of bundle branch block. Durations such as 60, 80, or 100 ms are within normal limits and do not define a wide complex.

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