thaler chapter 1

The Basics

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.

QRS

RSR

The earliest part of the QRS complex represents depolarization of

the interventricular septum by the septal fascicle of the left bundle