What is the treatment for complete heart block (Third-degree atrioventricular block)?

From the Guidelines

Complete heart block treatment requires immediate intervention with a permanent pacemaker implantation as the definitive therapy. For patients with symptomatic complete heart block (presenting with syncope, pre-syncope, heart failure, or hemodynamic instability), temporary pacing should be initiated while awaiting permanent pacemaker placement. Temporary pacing can be achieved through transcutaneous pacing pads (external pacing) or a transvenous temporary pacing wire. In emergency situations, medications like atropine (0.5-1mg IV, may repeat to maximum 3mg) can be used as a bridge to increase heart rate, though its effectiveness is limited in complete heart block. Isoproterenol (2-10 mcg/min IV infusion) may also be used temporarily to increase heart rate while awaiting pacemaker implantation. Dopamine (5-20 mcg/kg/min) or epinephrine (2-10 mcg/min) can be considered in hypotensive patients. The permanent pacemaker type (single or dual chamber) depends on the patient's underlying cardiac function and conduction system disease. Complete heart block occurs when electrical impulses from the atria cannot reach the ventricles due to conduction system damage, resulting in the ventricles beating at their own inherently slower rate (typically 20-40 beats per minute), which is insufficient to maintain adequate cardiac output and tissue perfusion, hence the need for artificial pacing to restore appropriate heart rate and atrioventricular synchrony.

Key Considerations

• The decision to implant a permanent pacemaker is based on the presence of symptoms and the type of atrioventricular block, as outlined in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
• Temporary pacing is recommended for patients with second-degree or third-degree atrioventricular block associated with symptoms or hemodynamic compromise that is refractory to medical therapy, as stated in the 2018 ACC/AHA/HRS guideline 1.
• The choice of pacemaker type depends on the patient's underlying cardiac function and conduction system disease, with techniques that provide more physiologic ventricular activation (e.g., cardiac resynchronization therapy, His bundle pacing) preferred in certain cases 1.

Treatment Approach

• Permanent pacemaker implantation is the definitive treatment for complete heart block, with temporary pacing used as a bridge to permanent pacing in symptomatic patients.
• Medications like atropine, isoproterenol, dopamine, and epinephrine may be used temporarily to increase heart rate in emergency situations, but their effectiveness is limited in complete heart block.
• The patient's underlying cardiac function and conduction system disease should guide the choice of pacemaker type, with a focus on restoring appropriate heart rate and atrioventricular synchrony.

From the FDA Drug Label

Atropine also may lessen the degree of partial heart block when vagal activity is an etiologic factor In some patients with complete heart block, the idioventricular rate may be accelerated by atropine; in others, the rate is stabilized.

Atropine may be used to treat complete heart block by accelerating the idioventricular rate or stabilizing the heart rate in some patients. However, its effectiveness can vary, and it may not work for everyone. Key points to consider:

• Atropine can lessen the degree of partial heart block when vagal activity is the cause.
• In complete heart block, atropine may accelerate the idioventricular rate or stabilize the heart rate. 2

From the Research

Treatment Options for Complete Heart Block

• Temporary pacemaker implantation and permanent pacemaker implantation are recommended in complete atrioventricular block cases that do not improve with reperfusion 3
• Dopamine and epinephrine may be considered for complete atrioventricular block if transfer to a higher level of care is not feasible and as bridge therapy while waiting for transfer 3
• Permanent pacemaker implantation is a class I indication for all symptomatic patients with complete heart block either congenital or acquired 4, 5
• Patients with Adams-Stokes attacks require pacing, while asymptomatic patients with complete heart block and those with minor symptoms should be assessed using studies of both ventricular pacemaker function and site 6

Management of Complete Heart Block

• Effective management includes accurate interpretation of a 12-lead EKG, assessment of hemodynamic stability and systemic perfusion, and time-sensitive pharmacologic or procedural intervention 7
• Administration of IV atropine, attempt transcutaneous pacing, placement of a transvenous pacemaker, and emergent consultation with interventional cardiology are appropriate management steps for complete heart block 7
• Consideration of the ventricular pacemaker function is important in assessing liability to syncope in complete heart block 6

Special Considerations

• Certain portions of patients with congenital complete heart block are asymptomatic, and implanting a permanent pacemaker is not always an easy decision 4
• A therapeutic dilemma arises when a select patient population does not meet certain criteria to gain the maximum benefits out of prophylactic pacemaker therapy 4, 5
• Patient-centered care and shared decision-making are important in cases where there is an incongruence between the principles of beneficence and patient autonomy 5