Sick sinus syndrome
(Redirected from Sick Sinus)
Background
- Also known as sinus dysfunction, sinoatrial node disease, and tachycardia-bradycardia syndrome (a specific variant)
- Collection of signs or symptoms that indicate sinus node dysfunction[1]
- May present as bradycardia, tachycardia, or alternating bradycardia and tachycardia
- 50% have alternating bradycardia and tachycardia (i.e. tachycardia-bradycardia syndrome)
Causes
- Intrinsic:
- Degenerative fibrosis
- Infiltrative disease process (e.g. amyloidosis)
- Ion channel dysfunction
- SA node remodeling
- Myocardial ischemia
- Extrinsic:
- Pharmacologic
- Metabolic/electrolyte disturbance
- Autonomic dysfunction
- Obstructive sleep apnea
Clinical Features
- Syncope or presyncope (50%)
- Palpitations
- Fatigue
- Generalized weakness
- Dyspnea
- Angina
- Disturbed sleep
- Confusion
Differential Diagnosis
Narrow-complex tachycardia
- Regular
- AV Node Independent
- Sinus tachycardia
- Atrial tachycardia (uni-focal or multi-focal)
- Atrial fibrillation
- Atrial flutter
- Idiopathic fascicular left ventricular tachycardia
- AV Node Dependent
- AV Node Independent
- Irregular
- Multifocal atrial tachycardia (MAT)
- Sinus tachycardia with frequent PACs, PJCs, PVCs
- Atrial fibrillation
- Atrial flutter with variable conduction
- Digoxin Toxicity
Symptomatic bradycardia
- Cardiac
- Inferior MI (involving RCA)
- Sick sinus syndrome
- Neurocardiogenic/reflex-mediated
- Increased ICP
- Vasovagal reflex
- Hypersensitive carotid sinus syndrome
- Intra-abdominal hemorrhage (i.e. ruptured ectopic)
- Metabolic/endocrine/environmental
- Hyperkalemia
- Hypothermia (Osborn waves on ECG)
- Hypothyroidism
- Hypoglycemia (neonates)
- Toxicologic
- Infectious/Postinfectious
- Other
Evaluation
- ECG identification, inpatient telemetry, outpatient Holter monitoring, event monitoring, loop monitoring
- ECG frequently negative for findings early in disease course
Management
- Remove extrinsic factors and/or pacemakers
- Pacemakers do not reduce mortality, only decrease symptoms
- Consider reversible causes e.g. treat hyperkalemia or hypokalemia
- Atropine for bradycardia, progress to catecholamine or pacing
- consider aminophylline, which inhibits suppressive effects of adenosine on the SA node in: [2]
- Acute inferior MI with 2nd or 3rd degree AV block; 250mv IV bolus
- Heart transplant: 6mg/kg in 100-200mL of IV fluid over 20-30 minutes
- Spinal cord injury: 6mg/kg in 100-200mL of IV fluid over 20-30 minutes
Disposition
- Admit
Complications
- (50%) Tachy-brady syndrome with atrial fibrillation or atrial flutter
- (50%) AV block
See Also
External Links
References
- ↑ Semelka, M et Al. Sick Sinus Syndrome: A Review. Am Fam Physician. 2013 May 15;87(10):691-696. http://www.aafp.org/afp/2013/0515/p691.html
- ↑ Kusumoto FM, et al. 2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2019 Aug 20;74(7):e51-e156