(Draft) Bradycardia

🥼 Practice and Clinical
1

Etiology

  • Ischemia, such as right coronary artery ischemia,
    • Generally, β-blockers are used to reduce heart rate and myocardial oxygen consumption in myocardial ischemia, but some ischemias cause bradycardia; in these cases, β-blockers should not be used to avoid further lowering the heart rate.
  • Hyperkalemia, identify the cause.
  • Rare after surgery.

Diagnosis

Combine pulse rate, ECG, and blood pressure monitor for mutual reference; do not rely on a single source, or the following may occur:

  • ECG may be inaccurate; for example, a very high heart rate may actually be very low (in third-degree AV block, the P wave is particularly long and may be mistaken for a T wave).
  • Heart rate measured by blood pressure monitor may also be inaccurate.
  • Combine pulse palpation counting and machine measurements for comprehensive judgment of actual bradycardia.

Treatment

  • First determine if the heart rate is truly low.
  • Then, based on symptoms and heart rate, decide on observation or treatment.
    • 40+ beats/min: observe (resting heart rate is generally about 10 lower than during activity).
    • Below 40:
      • Try to identify and treat the cause:
        • Check ECG for ischemia.
        • Check blood potassium levels for hyperkalemia.
      • If causative factors are not resolved or cannot be identified immediately:
        • First choice is intravenous slow infusion of isoproterenol (raises blood pressure < raises heart rate).
        • Dopamine is an alternative (raises blood pressure > raises heart rate).
        • For emergency rescue, epinephrine intramuscular injection (strongly raises blood pressure and heart rate).
        • Traditional Chinese medicine:
          • Ningxinbao Capsules? (Cordyceps) — bidirectionally regulates heart rate, used when pacemakers or medication are ineffective.
          • Dansong Yangxin Capsules — for slow arrhythmias.
          • Wenxin Granules (mixed with propafenone) — for fast arrhythmias.
  • If oxygen saturation by pulse oximetry is 93%, arterial blood gas analysis is required.

ASI syndrome — syncope,