Sinus Arrhythmia in Cats
 
The sinoatrial node (SA Node, or SAN), also called the sinus node, is the initiator of electrical impulses within the heart, triggering the heart to beat, or contract, by firing off electrical surges (also called the heart's pacemaker). The sinus discharge rate depends on two opposing influences of the nervous system: stimulation from the vagus nerves (nerves that originate in the lower brain stem [medulla] and send signals to the autonomic organs of the body) decreases the spontaneous discharge rate and predominates over sympathetic stimulation (mediating the ...read more