Sick sinus syndrome
Sick sinus syndrome
Classification & external resources
| ICD-10 |
I49.5 |
| ICD-9 |
427.81 |
| OMIM |
163800 |
| DiseasesDB |
12066 |
| MedlinePlus |
000161 |
| eMedicine |
med/2132 |
Sick sinus syndrome, also called Sinus node dysfunction, is a group of abnormal heart rhythms (arrhythmias) presumably caused by a malfunction of the sinus node, the heart's "natural" pacemaker. Bradycardia-tachycardia syndrome is a variant of sick sinus syndrome where atrial flutter and fibrillation alternate with prolonged periods of asystole.
Causes
Sick sinus syndrome is a relatively uncommon syndrome. It can result in many abnormal heart rhythms (arrhythmias), including sinus arrest, sinus node exit block, sinus bradycardia, and other types of bradycardia (slow heart rate).
Sick sinus syndrome may also be associated with tachycardias (fast heart rate) such as paroxysmal supraventricular tachycardia (PSVT) and atrial fibrillation. Tachycardias that occur with sick sinus syndrome are characterized by a long pause after the tachycardia.
Abnormal rhythms are often caused or worsened by medications such as digitalis, calcium channel blockers, beta-blockers, sympatholytic medications, and anti-arrhythmics. Disorders that cause scarring, degeneration, or damage to the conduction system can cause sick sinus syndrome, including sarcoidosis, amyloidosis, Chagas' disease, and cardiomyopathies.
Sick sinus syndrome is more common in elderly adults, where the cause is often a non-specific, scar-like degeneration of the cardiac conduction system. Cardiac surgery, especially to the atria, is a common cause of sick sinus syndrome in children.
Coronary artery disease, high blood pressure, and aortic and mitral valve diseases may be associated with sick sinus syndrome, although this association may only be incidental.
Symptoms
Even though many types of sick sinus syndrome produce no symptoms, patients may present with:
- Stokes-Adams attacks - fainting due to asystole or ventricular fibrillation
- Dizziness or light-headedness
- Palpitations
- Chest pain or angina
- Shortness of breath
- Fatigue
- Headache
Diagnosis
Ambulatory monitoring of the electrocardiogram (ECG) may be necessary because arrhythmias are transient. The ECG may show any of the following
- Inappropriate sinus bradycardia
- Sinus arrest
- Sinoatrial block
- Atrial fibrillation with slow ventricular response
- A prolonged asystolic period after a period of tachycardias
- Atrial flutter
- Ectopic atrial tachycardia
- Sinus node reentrant tachycardia
Electrophysiologic tests are no longer used for diagnostic purposes because of their low specificity and sensitivity. Cardioinhibitory and vasodepressor forms of sick sinus syndrome may be revealed by tilt table testing.
Treatment
Bradyarrhythmias are well controlled with pacemakers, while tachyarrhythmias respond well to medical therapy. However, because both bradyarrhythmias and tachyarrhythmias may be present, drugs to control tachyarrhythmia may exacerbate bradyarrhythmia. Therefore, a pacemaker is implanted before drug therapy is begun for the tachyarrhythmia.
References
- Adan V, Crown LA (2003). "Diagnosis and treatment of sick sinus syndrome". Am Fam Physician 67 (8): 1725-32. PMID 12725451.
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Circulatory system pathology (I, 390-459) |
| Hypertension |
Hypertensive heart disease - Hypertensive nephropathy - Secondary hypertension (Renovascular hypertension) |
| Ischaemic heart disease |
Angina pectoris (Prinzmetal's angina) - Myocardial infarction - Dressler's syndrome |
| Pulmonary circulation |
Pulmonary embolism - Cor pulmonale |
| Pericardium |
Pericarditis - Pericardial effusion - Cardiac tamponade |
| Endocardium/heart valves |
Endocarditis - mitral valves (regurgitation, prolapse, stenosis) - aortic valves (stenosis, insufficiency) - pulmonary valves (stenosis, insufficiency) - tricuspid valves (stenosis, insufficiency) |
| Myocardium |
Myocarditis - Cardiomyopathy (Dilated cardiomyopathy, Hypertrophic cardiomyopathy, Loeffler endocarditis, Restrictive cardiomyopathy) - Arrhythmogenic right ventricular dysplasia |
Electrical conduction system
of the heart |
Heart block: AV block (First degree, Second degree, Third degree) - Bundle branch block (Left, Right) - Bifascicular block - Trifascicular block
Pre-excitation syndrome (Wolff-Parkinson-White, Lown-Ganong-Levine) - Long QT syndrome - Adams-Stokes syndrome - Cardiac arrest - Sudden cardiac death
Arrhythmia: Paroxysmal tachycardia (Supraventricular, AV nodal reentrant, Ventricular) - Atrial flutter - Atrial fibrillation - Ventricular fibrillation - Premature contraction (Atrial, Ventricular) - Ectopic pacemaker - Sick sinus syndrome |
| Other heart conditions |
Heart failure - Cardiovascular disease - Cardiomegaly - Ventricular hypertrophy (Left, Right) |
| Cerebrovascular diseases |
Intracranial hemorrhage/cerebral hemorrhage: Extra-axial hemorrhage (Epidural hemorrhage, Subdural hemorrhage, Subarachnoid hemorrhage)
Intra-axial hematoma (Intraventricular hemorrhages, Intraparenchymal hemorrhage) - Anterior spinal artery syndrome - Binswanger's disease - Moyamoya disease |
Arteries, arterioles
and capillaries |
Atherosclerosis (Renal artery stenosis) - Aortic dissection/Aortic aneurysm (Abdominal aortic aneurysm) - Aneurysm - Raynaud's phenomenon/Raynaud's disease - Buerger's disease - Vasculitis/Arteritis (Aortitis) - Intermittent claudication - Arteriovenous fistula - Hereditary hemorrhagic telangiectasia - Spider angioma |
Veins, lymphatic vessels
and lymph nodes |
Thrombosis/Phlebitis/Thrombophlebitis (Deep vein thrombosis, May-Thurner syndrome, Portal vein thrombosis, Venous thrombosis, Budd-Chiari syndrome, Renal vein thrombosis, Paget-Schroetter disease) - Varicose veins / Portacaval anastomosis (Hemorrhoid, Esophageal varices, Varicocele, Gastric varices, Caput medusae) - Superior vena cava syndrome - Lymph (Lymphadenitis, Lymphedema, Lymphangitis) |
| Other |
Hypotension (Orthostatic hypotension) |
| See also congenital (Q20-Q28, 745-747) |
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