The normal pacemaker of the heart is the _____ node, which is ...

[rachel9]

The normal pacemaker of the heart is the _____ node, which is found in the _____ atrium, and has an intrinsic firing rate of _____ beats/min.
 
  a. sinoatrial; left; 40 to 60
  b. sinoatrial; right; 60 to 100
  c. atrioventricular; left; 20 to 40
  d. atrioventricular; right; 100 to 180

Question 2

Which of the following best describes an accelerated idioventricular rhythm (AIVR)?
 
  a. Rapid, chaotic rhythm with no pattern or regularity
  b. Gradual alteration in the amplitude and direction of the QRS; atrial rate indiscernible, ventricular rate 150 to 250 beats/min
  c. Regular ventricular rhythm with QRS complexes measuring 0.10 seconds or less; P waves may occur before, during or after the QRS; ventricular rate 41 to 60 beats/min
  d. Essentially regular ventricular rhythm with QRS complexes measuring 0.12 seconds or greater; atrial rate not discernible; ventricular rate 41 to 100 beats/min

[sultana.d]

Answer to Question 1

B
The sinoatrial (SA) node is normally the primary pacemaker of the heart because it has the fastest firing rate of all of the heart's normal pacemaker sites (60 to 100 beats/min). The SA node is located in the upper posterior part of the right atrium where the superior vena cava and the right atrium meet.

Answer to Question 2

D
Characteristics of accelerated idioventricular rhythm:
Rhythm Ventricular rhythm is essentially regular.
Rate 41 to 100 (41 to 120 per some cardiologists) beats/min
P waves Usually absent or, with retrograde conduction to the atria, may appear after the QRS (usually upright in the ST segment or T wave)
PR interval None
QRS duration Greater than 0.12 seconds; the T wave frequently in the opposite direction of the QRS complex

[rachel9]

Excellent

[raili21]

Gracias!