Disease Description (Causes and Symptoms)

Definition: Sick sinus syndrome (SSS) is a group of arrhythmias caused by the failure to generate or transmit normal electrical signals from the sinoatrial node (the heart’s natural pacemaker). It includes bradycardia (persistent slow heart rate), prolonged sinus pauses (temporary cessation of the heartbeat), sinus arrest, or alternating bradycardia and tachycardia (tachycardia-bradycardia syndrome).
Main causes and pathophysiology
- Age-related fibrosis and degeneration of the sinoatrial node (aging-related changes) are the most common cause.
- Structural heart diseases, such as ischemic heart disease (myocardial infarction), cardiomyopathy, valvular heart disease, and changes in the thoracic structure after surgery for congenital heart disease.
- Electrolyte abnormalities (e.g., hyperkalemia) and endocrine or metabolic abnormalities such as hypothyroidism.
- Various medications (beta-blockers, non-dihydropyridine calcium channel blockers [verapamil and diltiazem], digoxin, and some antiarrhythmic and antipsychotic drugs) may worsen sinus node function.
- Autonomic nervous system imbalance and genetic causes.
Main symptoms
- Dizziness, syncope (presyncope), fatigue, exercise intolerance, shortness of breath, palpitations (especially when tachycardia and bradycardia coexist), chest pain, and others.
- Symptoms may be absent depending on the severity of sinus node dysfunction and whether it is temporary.

Treatment

General principles
- First identify and correct potentially reversible causes, such as medications and electrolyte or endocrine abnormalities.
Medication treatment
- In patients with bradycardia, first consider discontinuing or adjusting the dosage of medications that cause or worsen bradycardia.
- Coexisting tachycardia (e.g., atrial fibrillation) should be controlled with antiarrhythmic drugs, but medication selection and use require caution when bradycardia is present (medication treatment is often combined with pacemaker implantation).
Procedures/mechanical treatment
- Implantation of a pacemaker (permanent pacemaker) is the standard treatment when persistent symptoms or recurrent syncope or severe bradycardia is present (or when bradycardia continues even after discontinuing medications).
- In tachycardia-bradycardia syndrome, medication or ablation/catheter ablation for the tachycardia is usually considered after implantation of a permanent pacemaker.
Lifestyle management and follow-up
- When symptoms such as dizziness or syncope occur, activity restrictions (such as driving or operating machinery) and safety measures are recommended.
- After pacemaker implantation, regular device checks (outpatient or remote monitoring) are necessary.
Precautions
- Immediate emergency evaluation is needed if symptoms are severe (such as syncope or persistent chest pain).
- Do not stop or change medications on your own; consult a doctor to adjust medications.

Items/information to bring:

A list of all currently taken medications (including prescription drugs, OTC drugs, and supplements) and the times they are taken
Copies of previous cardiac test results (electrocardiogram, Holter monitor, event recorder, echocardiogram, etc.), if available
Symptom diary: date and time symptoms occurred, duration, triggers (exercise, meals, medication use, etc.), whether syncope occurred, and related circumstances
Past medical history (myocardial infarction, valvular disease, heart surgery, etc.) and family history (sudden death, arrhythmias, etc.)
Allergies and whether you have any implanted devices (such as a pacemaker)
Information about medications recently discontinued or newly started Points to check before the visit:
Whether syncope or severe dizziness has occurred recently
Whether you drive or operate heavy machinery (safety-related counseling is needed if symptoms occur)
Possibility of pregnancy (must be checked before certain tests or treatments)

What is causing this condition? Which factors are important in my case?
What are the side effects of this medication (or the medication you are planning to prescribe)? In particular, what are the risks related to bradycardia or dizziness?
What tests are needed to definitively diagnose the cause of my symptoms (syncope/dizziness)?
Do I need a permanent pacemaker? If so, what type of device is appropriate?
What is the prognosis? How will my quality of life or activities, such as driving and exercise, be restricted?
What will the schedule be for regular tests or follow-up after treatment?

Could you explain specifically whether my symptoms (e.g., recurrent syncope or prolonged sinus pauses) meet the clear indications for pacemaker implantation?
Could my current medications (e.g., beta-blockers, calcium channel blockers, or digoxin) be causing or worsening my symptoms? Are there medications that can be discontinued or substituted?