ACLS Provider: Course

Bradycardia Algorithm

Bradycardia is defined as a heart rate of less than 50 beats per minute in adults. While a slow heart rate is not always symptomatic (some well-trained athletes, for example, may have resting heart rates below 60 bpm without any adverse effects), severe bradycardia can significantly compromise cardiac output, leading to inadequate tissue perfusion and potentially life-threatening conditions. Therefore, it is crucial to assess not only the heart rate but also the patient's clinical presentation.

Recognizing Bradycardia:

Symptoms: The symptoms of symptomatic bradycardia result from decreased cardiac output and inadequate oxygen delivery to the tissues. These may include:

  • Hypotension – low blood pressure due to the heart's inability to pump sufficient blood.
  • Altered Mental Status – dizziness, lightheadedness, syncope (fainting), confusion, or decreased level of consciousness due to reduced blood flow to the brain.
  • Signs of Shock – pale, cool, clammy skin, weak or thready pulse, and slow capillary refill, indicating poor peripheral perfusion.
  • Chest Discomfort (Angina) – chest pain or pressure due to insufficient oxygen supply to the heart muscle.
  • Heart Failure – shortness of breath, fatigue, and peripheral edema (swelling) due to the heart's inability to pump blood effectively.

ECG Findings:

  • Heart Rate < 50 bpm – this is the defining characteristic of bradycardia.
  • Prolonged PR Intervals – this can indicate a delay in conduction through the AV node.
  • Other Arrhythmias – bradycardia can be associated with:
    • Sinus Bradycardia
    • First-degree AV block
    • Second-degree AV block (Mobitz Type I and Type II)
    • Third-degree (complete) AV block

ACLS Bradycardia Algorithm:

  1. Identify and treat underlying causes – this is crucial for addressing the root of the problem.
  2. Maintain Airway – ensure a patent airway and provide supplemental oxygen as needed.
  3. Provide Oxygen – administer oxygen to improve oxygen saturation and tissue oxygenation.
  4. Monitor ECG – continuously monitor the patient's ECG to identify any changes in rhythm or response to treatment.
  5. Consider potential causes such as:
    • Hypoxia
    • Electrolyte imbalances (e.g., hyperkalemia)
    • Medications (e.g., beta-blockers, calcium channel blockers)
    • Myocardial ischemia or infarction
    • Hypothermia

Assess if bradycardia is causing symptoms: If the patient is asymptomatic (no signs of poor perfusion), close monitoring is sufficient. However, if symptoms are present, proceed to the next steps.

Administer atropine: Atropine is the first-line pharmacologic treatment for symptomatic bradycardia. It is an anticholinergic medication that blocks the effects of the vagus nerve, increasing heart rate. The recommended dose is 0.5 mg IV every 3–5 minutes, with a maximum total dose of 3 mg.

Consider pacing: If atropine is ineffective in improving the patient's condition, transcutaneous pacing (TCP) should be initiated. TCP involves placing pacing pads on the patient's chest and delivering electrical impulses to stimulate the heart to contract.

Additional Medications: If TCP is unavailable or ineffective, or while preparing for TCP, consider an infusion of dopamine (2–20 mcg/kg/min) or epinephrine (2–10 mcg/min). These medications increase heart rate and improve cardiac contractility.