A. The PR intervals with 2nd degree AV heart block, type I

a. are constant.

b. are absent.

c. are shorter in duration than 0.12 seconds.

d. become progressively longer.

B. There will be an absence of PR intervals in

a. premature atrial complexes.

b. 1st-degree AV heart block.

c. 3rd-degree AV heart block.

d. wandering atrial pacemaker.

C.  Type II, 2nd degree AV heart block has PR intervals that

a. continually change in duration.

b. are constant.

c. have no relationship.

d. are less than 0.12 seconds in duration.

D.  With atrial dysrhythmias, the

a. atrial waveforms differ in appearance from normal sinus P waves.

b. P9R intervals are almost always prolonged.

c. QRS complexes are wider than normal.

d. site of origin is in the bundle of His.