Sinuatrial block (synonym: SA block; ICD-10 I45.5: other specified heart block) is a cardiac arrhythmia that belongs to the group of conduction disorders.
SA block is a malfunction of the sinoatrial node or a delay or interruption of conduction from the sinoatrial node to the atrial muscles.
The following degrees of severity of sinuatrial block are distinguished:
- 1st-degree SA block – conduction delay from sinus node to atrial myocardium (atrial musculature).
- SA block 2nd degree – PP interval with pauses; Wenckebach and Mobitz periodicity.
- SA block 3rd degree – lack of excitation propagation in the atrium.
For details, see Causes.
Course and prognosis: In an otherwise heart-healthy patient, sinuatrial blocks are harmless. However, once they lead to symptoms such as syncope (brief loss of consciousness) and poor performance, they require therapy.
