Conduction disorders

Disease Description (Causes and Symptoms)

• Definition: A general term for a condition in which the conduction of electrical impulses is delayed or blocked at any point in the normal pathway, in which electrical impulses generated by the sinoatrial node are transmitted to the atrioventricular node and through the ventricular conduction system (e.g., right bundle branch block, left bundle branch block, atrioventricular conduction disorders).
• Main causes
  • Myocardial cell damage · myocardial ischemia (ischemic heart disease, cardiomyopathy)
  • Electrolyte abnormalities: hypokalemia · hyperkalemia · hypocalcemia
  • Medications (antiarrhythmic drugs, beta-blockers, calcium channel blockers, etc.)
  • Acute infections, atrial/ventricular enlargement
  • Lifestyle factors such as alcohol consumption · smoking · excessive caffeine intake
• Pathophysiology: Structural damage to the electrical conduction pathway or changes in the electrical environment cause conduction delay or block, disrupting the synchronization of the heartbeat or blocking conduction to the ventricles. High-grade atrioventricular block can lead to a sustained decrease in the ventricular rate (bradycardia).
• Main symptoms
  • Asymptomatic (such as right bundle branch block found during a health examination)
  • Syncope or presyncope (dizziness, lightheadedness)
  • Shortness of breath (during exercise or when accompanied by heart failure)
  • Palpitations (when accompanied by tachycardia or premature contractions)
  • Fatigue · exercise intolerance caused by bradycardia

Treatment Methods (Standard Treatment · Precautions · Self-Management)

• General treatment according to the diagnosis
  • Mild cases (such as isolated asymptomatic right bundle branch block): follow-up observation and regular electrocardiograms without specific treatment
  • Atrioventricular block (especially high-grade block or block accompanied by cardiac symptoms): implantation of a permanent pacemaker is the standard treatment
  • Correction of electrolyte abnormalities: correction of the causative electrolyte imbalance (potassium · calcium, etc.)
  • Treatment of underlying heart disease: active treatment of causative diseases such as coronary artery disease · myocarditis · cardiomyopathy
  • Medication adjustment: discontinuation or dose adjustment of medications that inhibit conduction
  • Temporary emergency treatment: if symptoms are severe and bradycardia or high-risk findings are present on the ECG, intravenous atropine administration and use of a temporary pacemaker (transcutaneous/transvenous)
  • If necessary, an electrophysiological study may be performed to accurately identify the location of the lesion and establish a treatment plan
• Lifestyle management · precautions
  • Because syncope carries a risk of injury, decisions regarding driving, working at heights, and operating machinery should be made after consulting a doctor
  • Limit alcohol consumption · smoking · excessive caffeine intake
  • Consult a doctor when using medications or supplements that may cause electrolyte imbalances, particularly potassium imbalance
  • After pacemaker implantation: follow regulations for MRI and equipment that may cause electrical interference, and undergo regular device checks
• Risk of complications
  • Injury caused by syncope
  • Progression to complete atrioventricular block and possible cardiac arrest
  • Worsening prognosis if appropriate treatment is delayed (especially when underlying heart disease is present)

Checklist Before an Outpatient Visit (Items to Bring · Records · Sample Questions)

• Items to bring
  • List of medications currently being taken (including names · doses · times of administration)
  • Results of previous tests such as electrocardiograms (ECG), 24-hour Holter monitoring, and echocardiography (copies if possible)
  • Recent symptom records: time of symptom onset, duration, relationship to activities (e.g., after exercise · meals), and accompanying symptoms (syncope · shortness of breath, etc.)
  • Past medical history (heart disease, electrolyte abnormalities, surgical history) and family history (sudden death · arrhythmia)
  • Allergies and whether any implants are present (hearing aids · artificial pacemakers, etc.)
• Sample items for symptom records
  • Date, time, and frequency of symptoms (dizziness/syncope/palpitations)
  • Circumstances before and after the symptoms (at rest · during exercise · with changes in position, etc.)
  • Findings observed by people nearby during syncope (stoppage of breathing · convulsions, etc.)
• Examples of questions to prepare in advance for the outpatient visit (convenient to show directly to the doctor)
  • “Is a conduction disorder suspected as the cause of my recent syncope/dizziness?”
  • “What additional tests are needed (Holter monitoring, electrophysiological study), and when will they be performed?”

Examples of General Questions to Ask the Doctor

• Is this condition temporary, or does it need to be managed chronically?
• How likely is my conduction disorder to progress to cardiac arrest or a permanent decrease in heart rate?
• Do I need a pacemaker, and if so, what type (single-chamber · dual-chamber · CRT, etc.) do you recommend?
• Could any of my current medications worsen the conduction disorder? Which medications should be adjusted?
• What precautions should I take regarding lifestyle habits (exercise, alcohol consumption, driving)?

Examples of Disease-Specific Questions

• “Based on my ECG results, which type do I have—right bundle branch block, left bundle branch block, or atrioventricular block—and what treatment approach is recommended for that type?”
• “I recently fainted. What should I do first in an emergency? (e.g., criteria for going directly to the emergency room · first aid at home)”