Sick sinus syndrome (SSS) is a relatively uncommon heart rhythm disorder. SSS is not a specific disease, but rather a group of signs or symptoms that indicate the sinus node, the heart’s natural pacemaker, is not functioning properly. A person with SSS may have a heart rhythm that is too slow (bradycardia), too fast (tachycardia), or one that alternates between the fast and slow (bradycardia-tachycardia).
Atrial tachycardia is a supraventricular tachycardia (SVT) that does not require the atrioventricular (AV) junction, accessory pathways, or ventricular tissue for its initiation and maintenance. It occurs in persons with normal hearts and in those with structurally abnormal hearts, including individuals with congenital heart disease (particularly after surgery for repair or correction of congenital or valvular heart disease).
Inappropriate Sinus Tachycardia
Inappropriate Sinus Tachycardia (IST) is a condition in which an individual’s resting heart rate is abnormally high – greater than 100 beats per minute or rapidly accelerating to over 100 beats per minute without an identifiable cause; although small amounts of exercise, emotional or physical stress are triggering factors. An electrocardiogram (ECG) does not show any abnormalities as IST arises within the sinus node where the normal heart rhythm is generated. It is a relatively new disorder. Individuals with this condition can find themselves increasingly disabled and experiencing high levels of anxiety. IST is not a life threatening condition but it can be very debilitating. Where sinus tachycardia is identified it is important to rule out other treatable conditions before making the diagnosis of IST – it may be that there is a curable cause.