What does the QRS complex represent? a. Atrial depolarization ...

[APUS57]

What does the QRS complex represent?
 
  a. Atrial depolarization
  b. Ventricular contraction
  c. Ventricular repolarization
  d. Ventricular depolarization

Question 2

How would you differentiate a junctional escape rhythm at 40 beats/min from a ventricular escape rhythm at the same rate?
 
  a. It is impossible to differentiate a junctional escape rhythm from a ventricular escape rhythm.
  b. The junctional escape rhythm will have a narrow QRS complex; the ventricular escape rhythm will have a wide QRS complex.
  c. The rate (40 beats/min) would indicate a junctional escape rhythm, not a ventricular escape rhythm.
  d. The junctional escape rhythm will have a wide QRS complex; the ventricular escape rhythm will have a narrow QRS complex.

[Christopher]

Answer to Question 1

D
When the ventricles are stimulated, a QRS complex is recorded on the ECG. Thus, the QRS complex represents ventricular depolarization.

Answer to Question 2

B
Although junctional and ventricular rhythms are ectopic pacemaker sites, their rhythms can generally be differentiated by the width of their QRS complexes. The junctional escape rhythm will have a narrow QRS complex; the ventricular escape rhythm will have a wide QRS complex.