Sinoatrial block

Sinoatrial Block (SA Block)

During the event

Rate	Normal to slow	Defined by duration of frequency of block
Rhythm	Irregular when a block occurs	P wave	Upright and uniform, except during the dropped beat	PR interval	Normal (0.12 - 0.20 sec), except during the dropped beat	QRS	Normal (0.06 - 0.10 sec), except during the dropped beat

- Cardiac output will decrease, possibly causing syncope or dizziness. - Occurs in some multiple of the PP interval. - After dropped beat, cycles continue on time.