What is the next step for a patient with a third-degree atrioventricular (AV) block detected on telemetry?

From the Guidelines

The next step for a patient with a third-degree atrioventricular (AV) block detected on telemetry is immediate placement of a temporary pacemaker followed by evaluation for permanent pacemaker implantation, as indicated by the 2012 ACCF/AHA/HRS guidelines 1. This is a medical emergency requiring prompt intervention, as third-degree AV block can lead to significant morbidity and mortality if left untreated. The patient should be transferred to an intensive care unit setting with continuous cardiac monitoring.

• Key considerations in the management of third-degree AV block include:
  • Immediate placement of a temporary pacemaker to stabilize the patient's heart rate
  • Evaluation for permanent pacemaker implantation, as indicated by the guidelines 1
  • Investigation of the underlying cause of the heart block, including medication review, electrolyte assessment, and evaluation for structural heart disease
  • Administration of atropine (0.5-1 mg IV every 3-5 minutes, maximum 3 mg) if the patient is symptomatic with hypotension, although its effectiveness is limited in complete heart block
  • Initiation of transcutaneous pacing if the patient is hemodynamically unstable while awaiting transvenous pacemaker placement
  • Use of dopamine (2-10 mcg/kg/min) or epinephrine (2-10 mcg/min) infusions to temporarily support blood pressure if necessary According to the guidelines, permanent pacemaker implantation is indicated for third-degree and advanced second-degree AV block at any anatomic level associated with bradycardia with symptoms, ventricular arrhythmias, or other medical conditions that require drug therapy that results in symptomatic bradycardia 1.
• The guidelines also recommend permanent pacemaker implantation for third-degree and advanced second-degree AV block at any anatomic level in awake, symptom-free patients with documented periods of asystole greater than or equal to 3.0 seconds or any escape rate less than 40 bpm, or with an escape rhythm that is below the AV node 1.

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.

The next step for a patient with a third-degree atrioventricular (AV) block detected on telemetry may involve the administration of atropine to potentially accelerate the idioventricular rate or stabilize it, as it can lessen the degree of partial heart block when vagal activity is an etiologic factor. However, the clinical decision should be made with caution, considering the patient's specific condition and the potential effects of atropine on the heart. 2

From the Research

Next Steps for Third-Degree Atrioventricular (AV) Block

The next steps for a patient with a third-degree atrioventricular (AV) block detected on telemetry include:

• Assessment of hemodynamic stability and systemic perfusion 3
• Accurate interpretation of a 12-lead EKG to determine the location of the block and the presence of a functioning secondary pacemaker within the conduction system 3
• Time-sensitive pharmacologic or procedural intervention, such as:
  • Administration of IV atropine 3
  • Attempting transcutaneous pacing 3
  • Placement of a transvenous pacemaker 3
  • Emergent consultation with interventional cardiology 3
• Consideration of dopamine and epinephrine as bridge therapy while waiting for transfer to a higher level of care, if transfer is not feasible 4
• Potential use of isoprenaline infusion as a feasible choice for unstable and symptomatic complete atrioventricular block, with a higher satisfactory clinical response rate compared to dopamine 5

Considerations for Asymptomatic Patients

For asymptomatic patients with third-degree AV block, the treatment approach is debated and not entirely clear 6. However, permanent pacemaker (PM) placement may be considered, taking into account the risks of complications associated with PM implantation.

Advanced Pacing Strategies

In some cases, advanced pacing strategies such as permanent His bundle pacing combined with left bundle branch pacing may be considered as a treatment option for patients with atrial fibrillation complicated by third-degree AV block 7.