From the Guidelines
Symptomatic bradycardia requires prompt intervention with atropine 0.5 mg IV as first-line treatment, which can be repeated every 3-5 minutes up to a maximum dose of 3 mg, as recommended by the 2018 ACC/AHA/HRS guideline 1.
Treatment Approach
The treatment approach for symptomatic bradycardia involves:
- Identifying and addressing the underlying cause, which may include medication side effects, electrolyte abnormalities, hypothyroidism, increased vagal tone, or heart block
- Administering oxygen if hypoxemia is present
- Implementing continuous cardiac monitoring
- Considering permanent pacemaker implantation for patients with recurrent episodes
Medication Options
If atropine is ineffective, other medication options include:
- Dopamine infusion (5 to 20 mcg/kg/min IV) 1
- Epinephrine infusion (2-10 mcg/min IV) 1
- Isoproterenol (20–60 mcg IV bolus followed by doses of 10–20 mcg, or infusion of 1–20 mcg/min) 1
- Theophylline (100 to 200 mg slow injection IV) for specific cases such as inferior myocardial infarction, cardiac transplant, or spinal cord injury 1
Pacing Options
Temporary pacing can be implemented transcutaneously, via a transesophageal approach, or by insertion of a transvenous pacing electrode 1.
Goal of Treatment
The goal of treatment is to increase heart rate to improve cardiac output and tissue perfusion, thereby resolving symptoms and preventing progression to cardiac arrest. It is crucial to distinguish between physiological bradycardia due to autonomic conditions or training effects and circumstantially inappropriate bradycardia that requires permanent cardiac pacing 1.
From the FDA Drug Label
Atropine-induced parasympathetic inhibition may be preceded by a transient phase of stimulation, especially on the heart where small doses first slow the rate before characteristic tachycardia develops due to paralysis of vagal control Adequate doses of atropine abolish various types of reflex vagal cardiac slowing or asystole The drug also prevents or abolishes bradycardia or asystole produced by injection of choline esters, anticholinesterase agents or other parasympathomimetic drugs, and cardiac arrest produced by stimulation of the vagus.
Symptomatic Bradycardia can be treated with atropine, as it abolishes reflex vagal cardiac slowing or asystole and prevents or abolishes bradycardia. Atropine is effective in increasing heart rate by paralyzing vagal control. 2
From the Research
Symptomatic Bradycardia Management
- Symptomatic bradycardia can be managed using various strategies, including observation, non-invasive management, and permanent pacemaker (PPM) implantation 3.
- Transcutaneous cardiac pacing (TCP) is a rapid, time-saving, and noninvasive ventricular stimulation that can be used to treat symptomatic bradycardias, with a significant improvement in mean systolic and diastolic blood pressure and median heart rate 4.
- A study comparing TCP with dopamine for unstable bradycardia found that survival to discharge or 30 days in hospital was similar in both groups, with 70% and 69% survival rates, respectively 5.
Treatment Outcomes
- Adverse events related to bradycardia, such as syncope, central line-associated bloodstream infections, cardiac arrest, and in-hospital mortality, were similar in patients who underwent early compared to delayed PPM implantation 3.
- Temporary transvenous pacing was associated with a higher rate of adverse events (19.1% vs 3.4%, P<.001) compared to PPM implantation 3.
- Weekend admissions were associated with increased temporary transvenous pacing, prolonged median time to PPM implantation, and prolonged median length of stay 3.
Clinical Considerations
- The choice of management strategy for symptomatic bradycardia depends on the underlying cause of the bradycardia, with reversible causes such as medication toxicity and hyperkalemia requiring different management approaches 3.
- Early PPM implantation may be considered to reduce the need for temporary transvenous pacing and shorten length of stay, especially in patients admitted on weekends 3.
- TCP can be an effective treatment modality for patients with atropine-resistant unstable bradycardia, with significant improvements in clinically significant vital signs and electrocardiography 4.