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. Full definition
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)