1. a. SSS b. SA block c. SA arrest Sick sinus syndrome is a disorder characterized by a dysfunctional sinus node. It is often idiopathic and a result of degenerative fibrosis of nodal tissue. Certain disorders such as amyloidosis, connective tissue disease, Chagas disease, and hemochromatosis are examples of intrinsic causes. Hypertensive heart disease and cardiomyopathies account for a smaller...

A 50-year-old university professor originally from South America had a 3-day history of paroxysmal attacks of rapid palpitations accompanied by near syncope and followed by transient flushing of her head and neck. She had a history of rheumatic mitral valve stenosis due to rheumatic fever at age 15, for which successful mitral commissurotomy was performed at age 36. Subsequently, recurrent atta...

BACKGROUND Familial sick sinus syndrome is associated with gene mutations and dysfunction of ion channels. In contrast, degenerative fibrosis of the sinus node tissue plays an important role in the pathogenesis of acquired sick sinus syndrome. There is a close relationship between transforming growth factor-β1 mediated cardiac fibrosis and acquired arrhythmia. It is of interest to examine wheth...

To test the hypothesis that the human sinus node is capable of demonstrating multiple sites of impulse generation, we assessed spontaneous shifts in the sinus node pacemaker complex, and shifts after overdrive atrial pacing, premature atrial stimulation and carotid sinus massage. A total of 24 patients aged 59 +/- 15 years (mean +/- SD) in whom stable sinus node electrograms were obtained were ...

The effect of digitalis in patients with sinoatrial node dysfunction was studied. Atrial pacing studies were performed while His bundle -electrograms were recorded in fourteen patients with sinus bradyeardia, syncope, or related symptoms. Measurements were repeated after 0.01 mg/kg ouabain, followed in some by 1 mg atropine. Ouabain produced a significant shortening of sinoatrial recovery time,...