Sick sinus syndrome is a group of abnormalities that prevent the sinoatrial node from performing its pacemaking function of the heart. It is characterized by sinus node dysfunction resulting in an atrial rate that is inappropriate for physiological needs. Common causes include ischemia, fibrosis, drugs, or infiltrative disorders. Symptoms include syncope, palpitations, and dizziness. Treatment of recurrent symptomatic bradycardia or prolonged pauses requires a permanent pacemaker.

1. ‫الرحمن‬ ‫هللا‬ ‫بسم‬‫الرحیم‬

2. SICK-SINUS
SYNDROME
Definition, Clinical Features and Treatment

3. Definition
• The term "sick-sinus syndrome" encompasses a number of abnormalities including sinus
bradycardia, sinus arrest, combinations of sinoatrial and AV blocks, and supraventricular
tachycardias, particularly atrial fibrillation and flutter.
• Defined by abnormal cardiac impulse formation and by abnormal propagation from the
sinoatrial node which prevent it from performing its pace-making function. It is characterized by
sinus node dysfunction with an atrial rate inappropriate for physiologic requirements.

4. • The abnormalities are usually due to ischemia, fibrosis ( often age-related and produced by
dysfunction of ion channels within SA), drug-induced (beta blockers, calcium channel blockers,
digoxin, sympatholytic medications, antiarrhythmic medications, lithium), infiltrative disorders
(haemochromatosis, sarcoidosis, connective tissue diseases) or autonomic dysfunction.

5. Clinical Features
• Many patients are asymptomatic.
• In others, clinical features are related to cerebral hypo perfusion and reduced cardiac output.
These can include syncope, palpitations and dizziness as well as symptoms caused by worsening
of underlying conditions such as congestive heart failure, angina pectoris and cerebrovascular
accident.
• Peripheral thromboembolism and stroke, which can occur in the presence of bradycardia-
tachycardia syndrome (alternating brady-arrhythmias and tachyarrhythmias), may be related to
dysrhythmia-induced emboli.
• A slow heart rate in the presence of fever, left ventricular failure or pulmonary edema may be
suggestive of sick-sinus syndrome.

6. Treatment
• Treatment of recurrent symptomatic bradycardia or prolonged pauses requires implantation of
a permanent pacemaker.