Sinus bradycardia

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Symptom/Sign: Sinus bradycardia
Classifications and external resources

ICD-10
ICD-9	427.81
MeSH	D001146

Sinus bradycardia is a heart rhythm that originates from the sinus node and has a rate of under 60bpm.

Contents 1 Etiology 2 ECG Characteristics 3 Significance 4 See also

[edit] Etiology

• This rhythm may be caused by one of the following:
  • Increased vagal tone.
  • Intrinsic disease of the SA node.
  • An effect of drugs, such as the use of digitalis, beta-blockers, or quinidine.
  • Sleep
  • It could also be a normal finding in a healthy, well-conditioned person.

[edit] ECG Characteristics

• Rate: Less than 60.
• Rhythm: Regular.
• P waves: Upright, consistent, and normal in morphology and duration.
• P-R Interval: Between 0.12-0.20 seconds in duration.
• QRS Complex: Less than 0.12 seconds in width, and consistent in morphology.

[edit] Significance

The decreased heart rate can cause a decreased cardiac output resulting in symptoms such as lightheadedness, dizziness, hypotension, vertigo, and syncope. The slow heart rate may also lead to atrial, junctional, or ventricular ectopic rhythms.

Sinus bradycardia is not necessarily a bad symptom. People who regularly practice sports may have sinus bradycardia, because their trained hearts can pump enough blood in each contraction.

[edit] See also

• Sinus tachycardia
• Long QT syndrome

v • d • e Cardiovascular disease: heart disease - Circulatory system pathology (I00-I52, 390-429) Ischaemic heart disease CHD: CAD - Coronary thrombosis - Coronary vasospasm - Coronary artery aneurysm Angina pectoris (Prinzmetal's angina) - Myocardial infarction (heart attack) Acute coronary syndrome - Myocardial rupture - Dressler's syndrome Pericardium Pericarditis (Acute pericarditis, Constrictive pericarditis) - Pericardial effusion - Cardiac tamponade Endocardium/ heart valves Endocarditis (Subacute bacterial endocarditis) mitral (regurgitation, prolapse, stenosis) - aortic (stenosis, insufficiency) - pulmonary (stenosis, insufficiency) - tricuspid (stenosis, insufficiency) Myocardium Myocarditis - Cardiomyopathy (Dilated cardiomyopathy, Hypertrophic cardiomyopathy, Loeffler endocarditis, Restrictive cardiomyopathy, Alcoholic cardiomyopathy) - Arrhythmogenic right ventricular dysplasia Electrical conduction/ arrhythmia heart block: AV (1°, 2°, 3°) - Bundle branch (Left, Right) - Bifascicular - Trifascicular - Sinoatrial - Sick sinus syndrome - Adams-Stokes syndrome pre-excitation syndrome: Wolff-Parkinson-White - Lown-Ganong-Levine tachycardia: Paroxysmal - Supraventricular (AV nodal reentrant, Accelerated idioventricular rhythm, Sinus) - Ventricular (Torsades de pointes) premature contraction: Atrial - Ventricular flutter/fibrillation: Atrial flutter - Ventricular flutter - Atrial fibrillation (Familial) - Ventricular fibrillation pacemaker: Wandering pacemaker - Ectopic pacemaker - Parasystole long QT syndrome: Romano-Ward syndrome - Andersen-Tawil syndrome - Jervell and Lange-Nielsen syndrome cardiac arrest: Sudden cardiac death Other Cardiomegaly - Ventricular hypertrophy (Left, Right) Cor pulmonale Heart failure - Rheumatic fever See also congenital (Q20-Q28, 745-747)