Definition
It is the dysfunction of SA node characterised by attacks of sinus bradycardia, sinus arrest or
junctional rhythm which may lead to dizziness or syncope, followed by episodes of paroxysmal tachycardia, so called tachy-brady syndrome.
It includes sinus arrest, SA block, persistent sinus bradycardia with tachycardia, paroxysomal
junctional or atrial tachycardia.
Causes
Due to fibrosis, degenerative changes or ischaemia of sinoatrial
node. Probable causes are as
follows:
• Elderly (due to degeneration).
• Ischaemic heart disease.
• Drug (digoxin).
• Cardiomyopathy.
• Rheumatic heart disease.
• Idiopathic in many cases.
Clinical Features
Symptoms
• May be asymptomatic.
• Dizziness, syncope, and palpitation.
Signs
• Pulse—bradycardia or tachycardia or drop beat.
• Features of primary disease.
Investigations
• ECG.
• Holter monitoring (single ECG may sometimes be normal).
Treatment
• If asymptomatic—no specific therapy. Follow-up.
• If symptomatic—permanent dual chamber pacemaker.
• Antiarrhythmic drug—may be required.