Page 1732 - Saunders Comprehensive Review For NCLEX-RN

▪ Normal QRS complex duration ranges from 0.04 to 0.1 second.

▪ The Q wave appears as the first negative deflection in the QRS complex and
reflects initial ventricular septal depolarization.
▪ The R wave is the first positive deflection in the QRS complex.

▪ The S wave appears as the second negative deflection in the QRS complex.
▪ The J point marks the end of the QRS complex and the beginning of the ST
segment.

▪ The QRS duration is measured from the end of the PR segment to the J point.
▪ The ST segment represents early ventricular repolarization.
▪ The T wave represents ventricular repolarization and ventricular diastole.
▪ The U wave may follow the T wave.
▪ A prominent U wave may indicate an electrolyte abnormality, such as
hypokalemia.
▪ The QT interval represents ventricular refractory time or the total time required
for ventricular depolarization and repolarization.
▪ The QT interval is measured from the beginning of the QRS complex to the end
of the T wave.
▪ The QT interval normally lasts 0.32 to 0.4 second but varies with the client’s
heart rate, age, and gender.

1732