Management of Sustained Bradycardia

Immediate Assessment and Intervention

For a patient with sustained heart rate of 36 BPM, immediately assess for hemodynamic instability and symptoms of poor perfusion—if present, administer atropine 0.5-1 mg IV as first-line therapy, repeatable every 3-5 minutes up to 3 mg total, while preparing for transcutaneous or transvenous pacing if medical therapy fails 1, 2
Signs of poor perfusion requiring immediate treatment include altered mental status, ischemic chest pain, acute heart failure, hypotension, or other signs of shock 3, 2
Obtain 12-lead ECG immediately to identify the rhythm mechanism 3, 2
Establish IV access, continuous cardiac monitoring, and pulse oximetry 3
A heart rate of 36 BPM is well below the 50 BPM threshold where bradycardia typically becomes symptomatic and requires intervention 3

Atropine has a Class IIa recommendation for symptomatic bradycardia with hemodynamic compromise 1
Atropine 0.5-1 mg IV push, repeat every 3-5 minutes to maximum total dose of 3 mg 1, 2
Contraindications for atropine include heart transplant patients without autonomic reinnervation and may worsen infranodal AV block 1, 5
Dopamine 5-20 mcg/kg/min IV and epinephrine 2-10 mcg/min IV are second-line treatments if atropine is ineffective 1, 2
Isoproterenol 1-20 mcg/min IV is an alternative, but avoid in suspected coronary ischemia 1

Transcutaneous pacing is a Class IIb recommendation for immediate bridge therapy in critically ill patients 8, 9, 1
Transvenous pacing is a Class IIa recommendation for persistent hemodynamic instability refractory to medical therapy 8, 7
Transvenous pacing has a higher complication rate, but is more reliable than transcutaneous pacing 8

Follow a structured approach for managing bradycardia, including atropine administration, pacing, and treatment of underlying causes 1, 2, 4
Recognize critical pitfalls to avoid, such as using atropine in heart transplant patients and rushing to permanent pacing within 72 hours of acute MI 1, 5, 9

The underlying mechanism of bradycardia matters, with high-grade AV block and sinus bradycardia/sinus arrest having different responses to atropine and pacing 5
Acute MI with bradycardia has a better prognosis with inferior MI than anterior MI with conduction disease 5