The phrase "sick sinus" refers to a problem with your heart's natural pacemaker, called the sinus node. It can cause the heart to beat too slowly, too fast, or irregularly.
Some dogs with sick sinus syndrome have a more constant sinus bradycardia (too slow) because the sinus node has a low firing rate. (www2.vet.cornell.edu)
The treatment goal for dogs with sick sinus syndrome is to achieve and maintain a normal heart rate. (healthypets.mercola.com)
Reykjavik, ICELAND, 6 March 2011 — Scientists at deCODE genetics and academic colleagues from Iceland, The Netherlands, Denmark, USA and Illumina, Inc., today report the discovery of single - letter variants (SNPs) in the sequence of the human genome associated with high risk of sick sinus syndrome (SSS). (decode.com)