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| | __NOTOC__ |
| | {| class="infobox" style="float:right;" |
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| | |[[File:Siren.gif|30px|link= Bradycardia resident survival guide]]||<br>||<br> |
| | |[[Bradycardia resident survival guide|'''Resident'''<br>'''Survival'''<br>'''Guide''']] |
| | |} |
| | {| class="infobox" style="float:right;" |
| {{Infobox_Disease | | | {{Infobox_Disease | |
| Name = Bradycardia | | | Name = Bradycardia | |
| Image = Lead II rhythm generated sinus bradycardia.JPG| | | Image = Lead II rhythm generated sinus bradycardia.JPG| |
| ICD10 = {{ICD10|R|00|1|r|00}} |
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| ICD9 = {{ICD9|427.81}}, {{ICD9|659.7}}, {{ICD9|785.9}}, {{ICD9|779.81}} |
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| }} | | }} |
| {{SI}} | | {{Bradycardia}} |
| {{WikiDoc Cardiology Network Infobox}} | | {{CMG}}; {{AE}} {{MUT}} {{Ibtisam}} |
| {{CMG}} | |
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| {{Editor Help}} | | {{SK}} Abnormally slow heartbeat, slow heartbeat |
| | ==[[Bradycardia overview|Overview]]== |
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| ==Overview== | | ==[[Bradycardia historical perspective|Historical Perspective]]== |
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| '''Bradycardia''', as applied to adult medicine, is defined as a resting [[heart rate]] of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min. <ref name=SINUS-BRADYCARDIA>[http://www.emedicine.com/emerg/topic534.htm Sinus Bradycardia] eMedicine</ref> Trained athletes tend to have slow resting heart rates, and resting bradycardia in athletes should not be considered abnormal if the individual has no symptoms associated with it.
| | ==[[Bradycardia classification|Classification]]== |
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| The term ''relative bradycardia'' is used to explain a heart rate that, while not technically below 60 beats per minute, is considered too slow for the individual's current medical condition.
| | ==[[Bradycardia pathophysiology|Pathophysiology]]== |
| | ==[[Bradycardia causes|Causes]]== |
| | ==[[Bradycardia differential diagnosis|Differentiating Bradycardia from other Conditions]]== |
| | ==[[Bradycardia epidemiology and demographics|Epidemiology and Demographics]]== |
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| This [[cardiac arrhythmia]] can be underlain by several causes, which are best divided into cardiac and non-cardiac causes.
| | ==[[Bradycardia risk factors|Risk Factors]]== |
| Non-cardiac causes are usually secondary, and can involve [[recreational drug use|drug]] use or [[drug abuse|abuse]]; [[metabolism|metabolic]] or [[endocrine]] issues, especially in the [[thyroid]]; an [[electrolyte]] imbalance; [[:Category:Neurology|neurologic]] factors; autonomic reflexes; situational factors such as prolonged bed rest; and [[autoimmune|autoimmunity]].
| | ==[[Bradycardia screening|Screening]]== |
| Cardiac causes include acute or chronic [[ischemic heart disease]], vascular [[heart disease]], [[valvular heart disease]], or degenerative primary electrical disease.
| | ==[[Bradycardia natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
| Ultimately, the causes act by three mechanisms: depressed automaticity of the heart, conduction block, or escape pacemakers and rhythms.
| | ==Diagnosis== |
| | | [[Bradycardia history and symptoms|History and Symptoms]] | [[Bradycardia physical examination|Physical Examination]] | [[Bradycardia laboratory findings|Laboratory Findings]] | [[Bradycardia electrocardiogram|Electrocardiogram]] | [[Bradycardia chest x ray|Chest X Ray]] | [[Bradycardia CT|CT]] | [[Bradycardia echocardiography or ultrasound|Echocardiography]] | [[Bradycardia other diagnostic studies|Other Diagnostic Studies]] |
| == Causes == | |
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| There are generally two types of problems that result in bradycardias: disorders of the [[sinus node]], and disorders of the [[atrioventricular node]] (AV node).
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| With sinus node dysfunction (sometimes called [[sick sinus syndrome]]), there may be disordered automaticity or impaired conduction of the impulse from the sinus node into the surrounding atrial tissue (an "exit block").
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| It is difficult and sometimes impossible to assign a mechanism to any particular bradycardia, but the underlying mechanism is not clinically relevant to treatment, which is the same in both cases of sick sinus syndrome: a permanent [[artificial pacemaker|pacemaker]].
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| Atrioventricular conduction disturbances (aka: AV block; [[First degree AV block|1<sup>o</sup> AV block]], [[Second degree AV block|2<sup>o</sup> type I AV block]], [[Second degree AV block|2<sup>o</sup> type II AV block]], [[Third degree AV block|3<sup>o</sup> AV block]]) may result from impaired conduction in the AV node, or anywhere below it, such as in the bundle of HIS.
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| Patients with bradycardia have likely acquired it, as opposed to having it [[congenital]]ly.
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| Bradycardia is more common in older patients.
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| <div align="left">
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| <gallery heights="175" widths="275">
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| Image:Lead II rhythm generated sinus bradycardia.JPG
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| </gallery>
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| </div>
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| ===Complete Differential Diagnosis of the Causes of Bradycardia=== | |
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| (In alphabetical order)
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| *[[Aceclidine]]
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| *[[Acepromazine]]
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| *[[Acetylcholinesterase inhibitor]]
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| *[[Adenosine]]
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| *[[Amiodarone]]
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| *[[Amodiaquine]]
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| *[[Anorexia Nervosa]]
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| *[[Apnea of prematurity]]
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| *[[Atenolol]]
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| *[[Atrioventricular Block]]
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| *[[Autonomic neuropathy]]
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| *[[Barbiturates]]
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| *[[Beta-blockers]]
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| *[[Bupivacaine]]
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| *[[Calcium channel blocker]]
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| *[[Cardiac arrhythmia]]
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| *[[Cardiac Dysrhythmias]]
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| *[[Cardiomegaly]]
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| *[[Catecholaminergic polymorphic ventricular tachycardia]]
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| *[[Cerebral Hemorrhage]]
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| *[[Cerebral venous sinus thrombosis]]
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| *[[Chronic Chagas' disease]]
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| *[[Clomipramine]]
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| *[[Congenital Long QT Syndrome]]
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| *[[Cushing reaction]]
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| *[[Cushing reflex]]
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| *[[Cushing's triad]]
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| *[[Detomidine]]
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| *[[Digitalis]]
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| *[[Diltiazem]]
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| *[[Diphenhydramine]]
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| *[[Donepezil]]
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| *[[Doxepin]]
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| *[[Drowning]]
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| *[[Emery-Dreifuss muscular dystrophy]]
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| *[[Enema]]
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| *[[Faget sign]]
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| *[[Fetal distress]]
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| *[[Gamma-Hydroxybutyric acid]]
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| *[[Gastric lavage]]
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| *[[Glyceryl trinitrate ]]
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| *[[Grayanotoxin]]
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| *[[Hantavirus pulmonary syndrome]]
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| *[[Hellebore]]
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| *[[Holt-Oram syndrome]]
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| *[[Hydrocodone]]
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| *[[Hydroxyethyl starch]]
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| *[[Hypercalcemia]]
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| *[[Hyperkalemia]]
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| *[[Hypokalemia]]
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| *[[Hypothermia]]
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| *[[Hypothyroidism]]
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| *[[Ibuprofen]]
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| *[[Intracranial pressure]]
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| *[[Isosorbide dinitrate]]
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| *[[Ivabradine]]
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| *[[Levobetaxolol]]
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| *[[Levobupivacaine]]
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| *[[Lidocaine]]
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| *[[Lithium]]
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| *[[Mammalian diving reflex]]
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| *[[Medetomidine]]
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| *[[Mefloquine]]
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| *[[Mepivacaine]]
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| *[[Methacholine]]
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| *[[Methoxamine]]
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| *[[Methyldopa]]
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| *[[Morphine]]
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| *[[Moxonidine]]
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| *[[Myxedema coma]]
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| *[[Nadolol]]
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| *[[Nalbuphine]]
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| *[[Nalmefene]]
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| *[[Neonatal lupus erythematosus]]
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| *[[Neostigmine]]
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| *[[Nesiritide]]
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| *[[Neurocardiogenic Syncope]]
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| *[[Neurogenic shock]]
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| *[[Norepinephrine]]
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| *[[Oculocardiac reflex]]
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| *[[Opioid]]
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| *[[Oxymorphone]]
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| *[[PCI Complications: Radiocontrast toxicity]]
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| *[[Phenobarbital]]
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| *[[Phenylephrine]]
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| *[[Phenytoin]]
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| *[[Pilocarpine]]
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| *[[Propafenone]]
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| *[[Propranolol]]
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| *[[Pulseless ventricular tachycardia]]
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| *[[Quinidine]]
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| *[[Rapid sequence induction]]
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| *[[Reserpine]]
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| *[[Right Bundle Branch Block]]
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| *[[Ropivacaine]]
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| *[[Second Degree AV Block]]
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| *[[Sick sinus syndrome]]
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| *[[Sinoatrial Block]]
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| *[[Speedball (drug)]]
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| *[[ST Elevation Myocardial Infarction Complications]]
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| *[[Subarachnoid hemorrhage]]
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| *[[Sulpiride]]
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| *[[Suxamethonium chloride]]
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| *[[Tacrine]]
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| *[[Theobromine poisoning]]
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| *[[Timolol]]
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| *[[Trazodone]]
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| *[[Trypanosoma cruzi]]
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| *[[Typhoid fever]]
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| *[[Uncaria tomentosa]]
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| *[[Vagal episode]]
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| *[[Vasa previa]]
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| *[[Vasovagal syncope]]
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| *[[Vertebral subluxation]]
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| *[[Xylazine]]
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| == Management ==
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| There are two main reasons for treating any [[cardiac arrhythmia]]s.
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| With bradycardia, the first is to address the associated symptoms, such as [[Fatigue (physical)|fatigue]], limitations on how much an individual can physically exert, [[fainting]] (syncope), [[dizziness]] or lightheadedness, or other vague and non-specific symptoms.
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| The other reason to treat bradycardia is if the person's ultimate outcome (prognosis) will be changed or impacted by the bradycardia.
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| Treatment in this vein depends on whether any symptoms are present, and what the underlying cause is.
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| Primary or [[idiopathic]] bradycardia is treated symptomatically if it is significant, and the underlying cause is treated if the bradycardia is secondary.
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| ==Treatment== | | ==Treatment== |
| | [[Bradycardia medical therapy|Medical Therapy]] | [[Bradycardia surgery|Surgery]] | [[Bradycardia primary prevention|Primary Prevention]] | [[Bradycardia secondary prevention|Secondary Prevention]] | [[Bradycardia cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Bradycardia future or investigational therapies|Future or Investigational Therapies]] |
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| Drug treatment for bradycardia is typically not indicated for patients who are asymptomatic. In symptomatic patients, underlying electrolyte or acid-base disorders or hypoxia should be corrected first. IV [[atropine]] may provide temporary improvement in symptomatic patients, although its use should be balanced by an appreciation of the increase in myocardial oxygen demand this agent causes.
| | ==Case Studies== |
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| [[Atropine]] 0.5-1 mg IV or ET q3-5min up to 3 mg total (0.04 mg/kg) | | :[[Bradycardia case study one|Case #1]] |
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| ==See also== | | ==Related Chapter== |
| * [[Normal sinus rhythm]]
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| * [[Tachycardia]]
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| * [[Hypotension]]
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| ==References==
| | *[[AV Block]] |
| {{reflist}}
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| {{SIB}} | | {{WikiDoc Sources}} |
| | | [[CME Category::Cardiology]] |
| [[de:Bradykardie]]
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| [[es:Bradicardia]]
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| [[fr:Bradycardie]]
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| [[it:Bradicardia]]
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| [[nl:Bradycardie]]
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| [[nn:Bradykardi]]
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| [[pl:Bradykardia]]
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| [[pt:Bradicardia]]
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| [[ru:Брадикардия]]
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| [[sk:Bradykardia]] | |
| [[sv:Bradykardi]]
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| [[Category:Cardiology]] | | [[Category:Cardiology]] |
| [[Category:Symptoms]] | | [[Category:Medical signs]] |
| | [[Category:Signs and symptoms]] |
| [[Category:Emergency medicine]] | | [[Category:Emergency medicine]] |
| | | [[Category:Arrhythmia]] |
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| {{WikiDoc Sources}}
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