- Establish intravenous (IV) / intraosseous (IO) access and place the patient on a cardiac, pulse oximeter, and blood pressure monitor.
- The American Heart Association (AHA) recommends using IV over IO when possible.
- Always consider transcutaneous or transvenous pacing in hemodynamically unstable patients whose medication management is ineffective or delayed.
- Hemodynamically unstable patients may be treated with IV atropine at 1.0 mg push every 3-5 minutes, for a total of 3 mg.
- Second-line drugs include IV dopamine at 5-20 mcg/kg/minute or IV epinephrine at 2-10 mcg/minute with titration to effective dose.
- Obtain initial ECG, electrolyte panel, troponin, and digoxin level (if indicated).
Complete atrioventricular (AV) block is a failure of atrial electrical impulse conduction to reach the ventricles. This may be persistent or paroxysmal and is associated with a junctional or ventricular escape rhythm. This results in significant bradycardia and a lack of coordinated atrial and ventricular contraction, which can significantly decrease cardiac output. Intermittent complete AV block can cause syncope or presyncope.
Etiologies include neonatal lupus erythematosus, congenital cardiac defects, myocarditis, rheumatic fever, Lyme carditis, bacterial endocarditis, myocardial ischemia, and infiltrative cardiomyopathy due to amyloidosis, sarcoidosis, systemic sclerosis, right coronary artery vasospasm, aortic dissection, or systemic lupus erythematosus. Second-degree type 2 AV blocks are also known to progress to third-degree AV block. Some AV nodal blocking medications, such as beta blockers, nondihydropyridine calcium channel blockers, and digoxin, may cause complete AV block. Manipulations such as cardiac surgery, central venous catheter placement, percutaneous coronary intervention, catheter ablation, percutaneous valve intervention, and alcohol septal ablation can cause complete AV block. Increased vagal tone can cause complete AV block in addition to electrolyte abnormalities. Some cases are idiopathic.
Predisposing history and risk factors include elderly age, male sex, history of myocardial infarction, and history of congestive heart failure. Modifiable risk factors include uncontrolled blood pressure as well as uncontrolled diabetes.
Presentations vary with the age of onset. Congenital complete heart block is generally irreversible. Cases resulting from neonatal lupus may present in utero or during infancy. Complications can include hydrops fetalis, pericardial effusion, and endocardial fibroelastosis.
Related topics: first-degree AV block, second-degree AV block
