thaler chapter 1

1   The Basics

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4. The first downward deflection following an upward deflection is called an S wave . Therefore, if the first wave of the complex is an R wave, the ensuing downward deflection is called an S wave, not a Q wave. A downward deflection can only be called a Q wave if it is the first wave of the complex. Any other downward deflection is called an S wave. 5. If the entire configuration consists solely of one downward deflection, the wave is called a QS wave . Here are several of the most common QRS configurations, with each wave component named.

RSR 1

QRS

RS

QR

QS

R

The earliest part of the QRS complex represents depolarization of the interventricular septum by the septal fascicle of the left bundle