1.1. Increased levels of Serum electrolytes, calcium, and/or magnesium
1.2. An excessively high digoxin level in patients on digoxin
1.3. Abnormal thyroid function
2. Pre-Hospital Treatment
2.1. Second-degree AV block Type 2 should be treated with immediate transcutaneous pacing or transvenous pacing because there is risk that electrical impulses will not be able to reach the ventricles and produce ventricular contraction.
2.2. Atropine may be attempted if immediate TCP is not available or time is needed to initiate TCP. Atropine should not be relied upon and in the case of myocardial ischemia it should be avoided.
3. Characteristics
3.1. 1. non-conducted p-waves (electrical impulse conducts through the AV node but complete conduction through the ventricles is blocked, thus no QRS)
3.2. 2. P-waves are not preceded by PR prolongation as with second-degree AV block (Type 1)
3.3. 3. fixed PR interval
3.4. 4. The QRS complex will likely be wide
4. Clinical Significants
4.1. Second-degree AV block Type 2 is clinically significant for ACLS because this rhythm can rapidly progress to complete heart block.
5. Symptoms
5.1. Light-headedness, dizziness, or syncope
5.2. Chest pain, if the heart block is related to myocarditis or ischemia
5.3. A regularly irregular heartbeat
5.4. Bradycardia may be present
5.5. Symptomatic patients may have signs of hypoperfusion, including hypotension
