Bradycardia

Disease Description (Causes and Symptoms)

• Definition: Bradycardia refers to a state in which the heart rate (pulse rate) generally falls to 60 beats per minute or lower; it is assessed differently depending on the individual's age and activity level.
• Main causes and pathophysiology:
  • Sinus node (sinus function) dysfunction: Reduced generation of normal impulses due to fibrosis, degeneration, or damage of the sinus node (such as age-related changes, after cardiac surgery, or inflammatory disease).
  • Atrioventricular conduction block (AV block): Electrical signals generated by the sinus node fail to reach the ventricles through the atrioventricular node and conduction system (first-, second-, or third-degree block).
  • Drug-induced: Beta blockers, calcium channel blockers (excluding the non-dihydropyridine class), digoxin, antiarrhythmic agents, etc.
  • Systemic causes such as ischemic heart disease, myocarditis, electrolyte abnormalities, and hypothyroidism.
• Main symptoms:
  • Fatigue, dizziness, lightheadedness, fainting (including presyncope), shortness of breath during exercise, lack of energy, and autonomic symptoms.
• Diagnostic tests include a 12-lead electrocardiogram (ECG), 24-hour Holter monitoring (ambulatory ECG), an event recorder or implantable loop recorder, and, when necessary, an electrophysiology study (EP study).

Treatment (Standard Treatment·Medications·Procedures·Lifestyle Management·Precautions)

• Acute and emergency treatment:
  • Symptomatic acute bradycardia: Intravenous atropine administration (initial treatment); if ineffective, continuous infusion of isoproterenol or dopamine, epinephrine, etc., and consideration of temporary pacing (transvenous or surgically applied patch-type pacing).
  • If hemodynamic instability occurs due to a persistent reduction in heart rate, immediate electrical/mechanical support (temporary pacing) is required.
• Chronic and established treatment:
  • In persistent sinus node dysfunction (sick sinus syndrome) accompanied by symptoms or advanced atrioventricular conduction block, implantation of a permanent artificial pacemaker is the standard treatment.
  • Drug therapy: Used selectively as a temporary or alternative treatment or when other treatments are contraindicated (for example, isoproterenol is not an oral substitute, and oral theophylline has been reported for use in some patients). Overall, the fundamental treatment for symptomatic bradycardia is a pacemaker; drug therapy is limited and selective.
• Lifestyle management and precautions:
  • Review and adjust medications that may cause bradycardia (beta blockers, some antiarrhythmic agents, digoxin, etc.).
  • Avoid dehydration, excessive alcohol or caffeine, and strong vagal stimulation (such as prolonged defecation or coughing).
  • If there is a risk of fainting, limiting high-risk activities (such as driving or working at heights) is recommended.
• Complications:
  • Trauma caused by recurrent fainting, worsening heart failure, and, rarely, life-threatening electrocardiographic abnormalities.
• Prognosis:
  • Varies depending on the cause, symptoms, and treatment, particularly appropriate pacemaker implantation. The prognosis is favorable when there are no symptoms, but may worsen when recurrent fainting or worsening heart failure is present.

Checklist Before an Outpatient Visit (Including Items to Bring and Example Questions)

• Items to bring to the outpatient visit:
  • A list of all medications currently being taken (including prescriptions, OTC medications, herbal medicines, and health functional foods)
  • Copies of recently performed ECGs, Holter monitoring results, and hospital records (with the dates and results, if possible)
  • Symptom diary: time symptoms occurred, duration, triggering circumstances (exercise, meals, posture, etc.), and accompanying symptoms (fainting, shortness of breath, etc.)
  • Medical history: heart disease, surgery, myocarditis, rheumatic disease, etc.
  • Allergies and possibility of pregnancy (for women)
• Items that are useful to record in advance for the outpatient visit:
  • Resting pulse measured under usual conditions (measured several times)
  • Posture and activity at the time of fainting or presyncope
• Show the doctor at the outpatient visit:
  • Medication list and ECG (or Holter) results
• Restrictions/precautions before the visit:
  • If you have results from a Holter monitor or event recorder, return the device and bring the report.

General Example Questions to Ask the Doctor

• "What is the exact cause of my bradycardia?"
• "Do any of the medications I am currently taking cause or worsen bradycardia? Should I stop taking them?"
• "If these symptoms persist, what additional tests will be needed?"
• "Is my condition one that requires a pacemaker? What are the risks and expected benefits of implantation?"
• "What should I be careful about in daily life to reduce the risk of fainting?"
• "What complications could occur if it is not treated?"

Examples of Condition-Specific Questions

• "I recently fainted (or had presyncope). In this situation, is immediate pacemaker implantation recommended?"
• "At what heart rate during exercise should I limit my activity? Please tell me the safety criteria for exercise (for example, when to stop if symptoms occur)."