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. If atropine is ineffective, other options such as transcutaneous pacing, dopamine infusion (5 to 20 mcg/kg/min) 1, or epinephrine infusion (2-10 mcg/min) 1 can be considered while preparing for transvenous pacing if needed. It is essential to identify and treat underlying causes of bradycardia, including medication side effects, electrolyte abnormalities, hypothyroidism, or heart block. Symptoms indicating intervention include hypotension, altered mental status, chest pain, shortness of breath, or syncope. Patients with heart rates below 50 beats per minute accompanied by these symptoms require immediate treatment. The goal is to increase heart rate and improve cardiac output to maintain adequate tissue perfusion. For long-term management, permanent pacemaker implantation may be necessary, particularly for high-degree AV blocks or symptomatic sinus node dysfunction that doesn't respond to medication adjustments or treatment of underlying causes, as stated in the 2012 ACCF/AHA/HRS focused update 1. Temporary pacing can be implemented transcutaneously, via a transesophageal approach, or by insertion of a transvenous pacing electrode, as described in the 2018 ACC/AHA/HRS guideline 1. Key considerations in managing symptomatic bradycardia include:
- Prompt recognition and treatment of underlying causes
- Appropriate use of atropine and other medications
- Consideration of temporary or permanent pacing
- Individualized management based on patient symptoms and underlying conditions.
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
Definition and Causes of Symptomatic Bradycardia
- Symptomatic bradycardia is defined as a heart rate lower than 60 beats/min, which can be due to sinus, atrial, or junctional bradycardia or to a problem with the conduction system (eg, an atrioventricular block) 3.
- Bradycardia symptoms can include syncope, dizziness, chest pain, dyspnea, or fatigue 3.
- Pathology that produces bradycardia may occur within the sinus node, atrioventricular (AV) nodal tissue, and the specialized His-Purkinje conduction system 4.
Evaluation and Management of Symptomatic Bradycardia
- It is important to determine during the evaluation if bradycardia is the cause of the patient's symptoms 3.
- Assessment of symptoms is a critical component in the evaluation and management of bradycardia 4.
- Treatment should rarely be prescribed solely on the basis of a heart rate lower than an arbitrary cutoff or a pause above certain duration 4.
Treatment Options for Symptomatic Bradycardia
- In the acute setting, symptomatic patients should be treated with atropine 3.
- Transcutaneous cardiac pacing (TCP) is a rapid, time-saving, and noninvasive ventricular stimulation that is tolerated by conscious patients despite the painful intervention for treatment of symptomatic bradycardias 5.
- Percutaneous pacing can be used as a bridge to definitive treatment 3.
- The only therapy for persistent bradycardia is placement of a permanent pacemaker 3.
- Symptomatic patients with sick sinus syndrome and high second- or third-degree atrioventricular blocks require placement of permanent pacemakers 3.