Bradycardia

What Is Bradycardia?

Bradycardia is a heart rate slower than 60 beats per minute in adults. It can be a normal physiological finding in well-conditioned athletes or during sleep, or it can signal a serious underlying problem — including myocardial infarction, electrolyte imbalance (especially hyperkalemia), hypothyroidism, medication effects (beta-blockers, calcium channel blockers, digoxin), increased intracranial pressure, or intrinsic conduction system disease like sick sinus syndrome or high-grade AV block. The key clinical question in the field isn't just the number on the monitor, but whether the patient is symptomatic — hypotension, altered mental status, chest pain, signs of shock, or acute heart failure — because a slow rate with adequate perfusion is managed very differently than a slow rate causing hemodynamic instability.

Why Bradycardia Matters on the Fireground

A bradycardic patient who is alert, warm, and well-perfused often needs nothing more than monitoring and transport, but a symptomatic bradycardic patient can deteriorate into cardiac arrest quickly if the underlying cause isn't identified and treated. EMS providers need to distinguish stable from unstable bradycardia fast, since treatments like atropine, transcutaneous pacing, or epinephrine infusion are indicated only when the slow rate is actually causing symptoms.

Relevant NFPA Standards

• AHA Guidelines: ACLS Bradycardia Algorithm
• NFPA 455: Standard for Emergency Medical Services (EMS)

Field Procedures & Tactical Steps

1. Obtain a full set of vitals and a 12-lead ECG to characterize the rhythm and rate.
2. Assess for signs of poor perfusion — hypotension, altered mental status, chest pain, signs of shock, or acute heart failure.
3. If the patient is stable and asymptomatic, monitor closely and transport without pharmacological intervention.
4. If symptomatic, follow the ACLS bradycardia algorithm: administer atropine per protocol, and prepare for transcutaneous pacing or an epinephrine/dopamine infusion if atropine is ineffective or contraindicated.
5. Identify and address reversible causes where possible, such as suspected beta-blocker or calcium channel blocker overdose, electrolyte abnormality, or hypoxia.

Common Context & Application

Identified on cardiac monitoring during medical calls involving syncope, chest pain, altered mental status, or overdose (particularly beta-blocker or calcium channel blocker ingestion), as well as incidentally in athletic or asymptomatic patients during routine vital sign checks.

Frequently Asked Questions about Bradycardia