What is the immediate management for a 91-year-old female patient with third (3rd) degree heart block in the Emergency Room (ER)?

Management of Third-Degree Heart Block in a 91-Year-Old Female in the Emergency Room

In a 91-year-old female with third-degree heart block and MAP of 40 mmHg in the emergency room, immediate transcutaneous pacing should be initiated while preparing for transvenous pacing, as this represents a life-threatening emergency requiring rapid intervention. 1, 2

Initial Assessment and Management

• Rapidly assess hemodynamic stability - with MAP of 40 mmHg, this patient is in shock and requires immediate intervention 2
• Establish IV access, administer supplemental oxygen, and place on continuous cardiac monitoring 1
• For this patient with symptomatic third-degree heart block and hypotension (MAP 40):
  • Begin transcutaneous pacing immediately 1, 3
  • Set initial current at 40-80 mA and increase until electrical capture is achieved 3
  • Confirm mechanical capture by checking for palpable pulses 3

Pharmacological Management

• Atropine (0.5 mg IV every 3-5 minutes to maximum of 3 mg) may be administered while preparing for pacing, but is likely to be ineffective in third-degree heart block at the infranodal level 1, 4
• Atropine is only effective for AV block at the nodal level (typically with narrow-complex escape rhythm) 1, 5
• Avoid doses less than 0.5 mg as they may paradoxically worsen bradycardia 1, 4
• Consider vasopressor support if hypotension persists despite pacing:
  • Dopamine (5-20 μg/kg/min) or epinephrine (2-10 μg/min) infusion 1, 6

Definitive Management

• Arrange for urgent cardiology consultation for transvenous pacemaker placement 1, 2
• Transvenous pacing is indicated for third-degree AV block with symptomatic bradycardia and hypotension 1
• The timing of intervention is critical - earlier pacing (within 5 minutes of presentation) is associated with better outcomes 7
• Permanent pacemaker implantation will likely be required as definitive treatment 1

Rationale for Management Approach

• Third-degree heart block in elderly patients is often due to degenerative conduction system disease and is unlikely to resolve spontaneously 1
• Guidelines clearly state that third-degree AV block associated with symptomatic bradycardia or low cardiac output is a Class I indication for permanent pacing 1
• Transcutaneous pacing is the preferred initial approach in emergency situations due to:
  • Rapid application compared to transvenous pacing 1, 3
  • Lower risk of complications in the acute setting 1
  • Bridge to definitive therapy 3

Monitoring and Additional Considerations

• Provide adequate sedation and analgesia for patient comfort during transcutaneous pacing 3
• Obtain 12-lead ECG to confirm diagnosis and determine if the block is at nodal or infranodal level 2
• Check electrolytes, particularly potassium, magnesium, and calcium levels 2
• Obtain cardiac enzymes to rule out acute myocardial infarction as the cause of heart block 2
• Consider reversible causes of heart block (medication effects, electrolyte abnormalities) 1
• Monitor for complications of pacing including failure to capture, diaphragmatic stimulation, and skin burns 3

Disposition

• The patient will require admission to an intensive care unit with continuous cardiac monitoring 2
• Definitive management with permanent pacemaker implantation should be planned 1