While bradycardia is defined as a heart rate of < 50 beats/minute, symptomatic bradycardia refers to weakness, a decreased level of consciousness, shortness of breath, hypotension, or chest pain that is the result of bradycardia. The treatment of bradycardia focuses on optimizing hemodynamics and addressing the underlying cause.
Patients with bradycardia often complain of dizziness, which is frequently exacerbated by positional changes that are resolved when positioned supine, or mild shortness of breath. These patients can be managed with supportive care only, provided they are otherwise asymptomatic.
Patients with adequate perfusion and a low heart rate may require monitoring and conveyance, but no treatment. Unless the patient requires immediate resuscitation, a conservative approach to management should prevail.
Clinical end points are defined by the amelioration of symptoms rather than any particular heart rate or blood pressure.
Management of the prevailing underlying condition is often more critical than correction of the dysrhythmia.
In all cases of bradycardia, consideration must be given to the overall clinical condition of the patient. Signs of effective perfusion (particularly skin colour, skin temperature, and mentation) are better indicators of the need for intervention than blood pressure (either systolic blood pressure or mean arterial pressure) alone. Paramedics and EMRs/FRs should have a nuanced understanding of the degree to which a patient is symptomatic.
In all cases of symptomatic bradycardia, search for and address treatable or reversible causes. Such cases may include:
Hypoxia (especially in younger patients)
Increased parasympathetic (vagal) tone
Drug effects or overdoses
Hyperkalemia, with or without concurrent metabolic acidosis
Myocardial ischemia, particularly if it involves the SA or AV nodes and conduction system
In the setting of myocardial infarction, bradycardia is often compensatory and somewhat beneficial. Be cautious of initiating rate-specific therapies as these may increase myocardial oxygen demand and extend the margins of infarct. Therapy should be reserved for those patients who are significantly hypotensive.
First Responder (FR) Interventions
Keep the patient warm and protect from further heat loss
Place the patient in a position of comfort, as permitted by clinical condition; in general, limit patient movement