Sinus Node Dysfunction
Sinus Node Dysfunction
- Refers to problems with sinus node impulse formation and propagation
- May include sinus bradycarda, sinus pauses or arrest, chronotropic incompetence, and sino-atrial exit block
- When accompanied by symptoms it is referred to as Sick Sinus Syndrome
- When associated with periods of paroxysmal supraventricular tachycardia it is referred to as Tachycardia-Bradycardia Syndrome or “Tachy-Brady Syndrome”
Causes of Sick Sinus Syndrome
- Idiopathic
- Ischemic heart disease
- Primary non-ischemic cardiomyopathy
- Hypertensive heart disease
- Secondary cardiomyopathy
- Connective tissue disease
- Syphilis
- Metastatic tumor
- Amyloidosis
- Myxedema
- Hemochromatosis
- Friedreich’s ataxia
- Muscular dystrophy
- Scleroderma
- Mitral valve prolapse
- Rheumatic heart disease
- Acute myocarditis
- Congenital heart disease
- Familial sinus node disease
- Surgical injury to the SA node (especially following repair of transposition of the great vessels)
- Following the Cox-Maze III procedure for management of atrial fibrillation
Tachycardia-Bradycardia Syndrome
- Observed in 54 to 76% of patients with Sick Sinus Syndrome
- Not a pure clinical or ECG entity but rather a constellation of cardiac rhythm disturbances and their clinical manifestations
- Occurs in all age groups but most common in the elderly
Indications for Permanent Pacing
- Sinus pauses of 3 seconds or greater
- Sustained symptomatic sinus rates of 40 BPM or less in the awake patient
See also: The basics of paced rhythms.
Example
A Sign of the Times?
Here’s an interesting example of new medicine relayed by a cardiologist colleague pic.twitter.com/uqKWeC1s9N
— Eric Topol (@EricTopol) July 15, 2015
Further Reading
Sinus Node Dysfunction at Life in the Fast Lane.
Sick Sinus Syndrome at the Heart Rhythm Society
Click here for a great case from Dr. Smith’s ECG Blog.
References
Epstein A, DiMarco J, Ellenbogen K et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities. Journal of the American College of Cardiology. 2008;51(21):e1-e62. doi:10.1016/j.jacc.2008.02.032.
Hayes D, Lloyd M, Friedman P. Cardiac Pacing And Defibrillation. Armonk, NY: Futura Pub. Co.; 2000.
Surawicz B, Knilans T, Chou T. Chou’s Electrocardiography In Clinical Practice. Philadelphia: Saunders; 2001.
Content Reviewer
Kelly A. Bouthillet, APRN, MSN, CCNS, ACNP-BC (@BarefootNurse24)