What is SA Block

Failure to inititate an impulse from SA node.

Causes of SA Block

• Degenerative changes in elderly.
• Ischaemic heart disease (involving SA node).
• Drugs (digoxin).
• Increased vagal tone (may present like sick sinus syndrome).


• May be asymptomatic.
• Dizziness, giddiness.


Drop beat and no heart sound at the time of drop beat.


• ECG—complete absence of one complex (P-QRS-T).
• Holter monitoring—may show the block.

Treatment of SA Block

• No treatment, if asymptomatic.
• Withdrawal of offensive drug, if any.
• If any syncopal attack or sick sinus syndrome—permanent pacemaker should be given.