A patient who has been diagnosed with myocardial infarction is getting an ECG. The ECG trace shows a series of nonconducted P waves followed by a P wave that is conducted to the ventri-cles

Question

The ratio of nonconducted to conducted P waves is fixed at 4:1. What plan for treatment should this patient receive?
1. Rapid defibrillation
2. Atropine
3. Cardioversion
4. Pacemaker
a. 1, 2, and 3 only
b. 2 and 4 only
c. 3 only
d. 1, 2, 3, and 4

Answer 1

ANS: B
Second-degree heart block comes in two different types. Type I (Wenckebach or Mobitz type I) block is a relatively benign and often transient arrhythmia. Type II second-degree heart block (Mobitz type II) is less common and is more often the result of serious problems such as MI or ischemia. Type II heart block is seen as a series of nonconducted P waves followed by a P wave that is conducted to the ventricles. Sometimes the ratio of nonconducted to conducted P waves is fixed at 3:1 or 4:1. The PR interval for the conducted impulses is consistent. Type II sec-ond-degree heart block requires treatment in most cases, because the resulting reduction in ven-tricular rate causes a drop in blood pressure. Medications such as atropine will provide a better cardiac output until a pacemaker can be inserted. Because type II may progress to third-degree heart block without warning, a pacemaker is indicated even if the patient is asymptomatic.