Bradycardia causes

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: M.Umer Tariq [2]

Overview

Pathologic bradycardias are caused by disorders of impulse generation (impaired automaticity at SA node), impulse conduction (heart block) or escape pacemakers and rhythms. Bradycardia can be underlain by several causes, which are best divided into cardiac and non-cardiac causes or based on the location of the abnormality. Non-cardiac causes are usually secondary, and can involve recreational drug use; endocrine disorders (hypothyroid); electrolyte imbalance (hyperkalemia); autonomic reflexes; situational factors (prolonged bed rest); infections lyme disease; medications; and autoimmunity disorders. Cardiac causes include acute or chronic ischemic heart disease, vascular heart disease, valvular heart disease, or degenerative primary electrical disease (fibrosis and calcification of the sinus node and conduction system).

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Acute coronary syndrome
• Acute myocardial infarction
• Acute renal failure
• Acute respiratory failure
• Acute rheumatic fever
• Bacterial endocarditis
• Beta blocker overdose
• Carbamate poisoning
• Cervical spine injury
• Diabetic ketoacidosis
• Digitalis toxicity
• Drowning
• Electric shock
• Electrolyte imbalance
• Hypoglycemia
• Increased intracranial pressure
• Lateral medullary syndrome
• Lily of the valley poisoning
• Lithium toxicity
• Myocardial infarction
• Myocardial rupture
• Myocarditis
• Nerve agent poisoning e.g. sarin
• NSTEMI
• Organophosphate poisoning
• Parathion poisoning
• Poisonous spider bites
• Pulmonary embolism
• Rabies
• Sepsis
• Septic shock
• Severe brain injury
• Severe hypothermia
• STEMI

Common Causes

• Bundle branch block
• Cardiac arrhythmia
• Complete or third-degree AV block
• First degree AV block
• Hashimoto's thyroiditis
• Myocardial infarction
• Second degree AV block
• Sick sinus syndrome
• Systemic lupus erythematosus

Causes of Bradycardia By Organ System

Cardiovascular	Atrioventricular Block, Cardiac arrhythmia, Cardiac Dysrhythmias, Cardiomegaly, Right Bundle Branch Block, Second Degree AV Block, ST Elevation Myocardial Infarction Complications, Sinoatrial Block, Pulseless ventricular tachycardia, Sick sinus syndrome, Cardiomyopathy, Distichiasis - heart and vasculature anomalies - sinus bradycardia
Chemical / poisoning	Carbamate, Opioid poisoning,
Dermatologic	No underlying causes
Drug Side Effect	Aceclidine, Acepromazine, Acetylcholinesterase inhibitor, Adenosine, Amiodarone, Amodiaquine, Atenolol, Barbiturates, Beta-blockers, Bupivacaine, Calcium channel blocker, Clomipramine, Clonidine, Detomidine, Digitalis, Diltiazem, Diphenhydramine, Donepezil, Doxepin, Glyceryl trinitrate , Hydrocodone, Ibuprofen, Isosorbide dinitrate, Ivabradine, Levobetaxolol, Levobupivacaine, Lidocaine, Lithium, Medetomidine, Mefloquine, Mepivacaine, Methacholine, Methoxamine, Methyldopa, Morphine, Moxonidine, Nadolol, Nalbuphine, Nalmefene, Opioid, Oxymorphone, Phenobarbital, Phenylephrine, Phenytoin, Pilocarpine, Propafenone, Propranolol, Quinidine, Reserpine, Ropivacaine, Sulpiride, Suxamethonium chloride, Tacrine, Timolol, Trazodone, Uncaria tomentosa, Xylazine,
Ear Nose Throat	No underlying causes
Endocrine	Hypothyroidism, Hashimoto's Thyroiditis,
Environmental	Grayanotoxin, Hellebore, Hypothermia, Heat exhaustion
Gastroenterologic	Obstructive jaundice, Necrotizing enterocolitis , Typhoid fever
Genetic	Congenital Long QT Syndrome, Catecholaminergic polymorphic ventricular tachycardia, Emery-Dreifuss muscular dystrophy, Congenital Central Hypoventilation Syndrome, Distichiasis - heart and vasculature anomalies - sinus bradycardia
Hematologic	No underlying causes
Iatrogenic	Enema, Gastric lavage, PCI Complications: Radiocontrast toxicity, Rapid sequence induction, Cardiac catheterization
Infectious Disease	Chagas' disease, Hantavirus pulmonary syndrome, Legionella pneumonia and Mycoplasma pneumonia, Tularaemia, Colorado tick fever, Brucellosis, Trypanosoma cruzi, Typhoid fever, Septic shock
Musculoskeletal / Ortho	Holt-Oram syndrome, Vertebral subluxation,
Neurologic	Vasovagal syncope, Vagal episode, Neurogenic shock, Subarachanoid hemorrhage, Raised Intracranial pressure, Autonomic neuropathy, Cerebral hemorrhage, Cerebral venous sinus thrombosis, Cushing triad, Cushing reaction, Cushing reflex, Neurocardiogenic Syncope, Increased intracranial pressure
Nutritional / Metabolic	Hypercalcemia, Hyperkalemia, Hypokalemia, Anorexia Nervosa, Malnutrition
Obstetric/Gynecologic	Fetal distress, Neonatal lupus erythematosus, Vasa previa,
Oncologic	No underlying causes
Ophthalmologic	Oculocardiac reflex, Distichiasis - heart and vasculature anomalies - sinus bradycardia
Overdose / Toxicity	Gamma-Hydroxybutyric acid, Hydroxyethyl starch Speedball (drug), Theobromine poisoning, Sedatives Cyclic antidepressant poisoning
Psychiatric	Anorexia Nervosa,
Pulmonary	Apnea of prematurity, Asphyxia neonatorum , Pneumothorax
Renal / Electrolyte	No underlying causes
Rheum / Immune / Allergy	No underlying causes
Sexual	No underlying causes
Trauma	Skull fracture
Urologic	No underlying causes
Miscellaneous	Drowning, Mammalian diving reflex,

Causes in Alphabetical Order

Aceclidine Acepromazine Acetylcholinesterase inhibitor Adenosine Amiodarone Amodiaquine Anorexia nervosa Apnea of prematurity Asphyxia neonatorum Atenolol Athletes Atrioventricular block Autonomic neuropathy Barbiturates Beta-blockers Brucellosis Bupivacaine Calcium channel blocker Carbamate Cardiac arrhythmia Cardiac catheterization Cardiac dysrhythmias Cardiomegaly Cardiomyopathy Catecholaminergic polymorphic ventricular tachycardia Cerebral hemorrhage Cerebral venous sinus thrombosis Chagas' disease Clomipramine Clonidine Colorado tick fever Congenital central hypoventilation syndrome Congenital long QT syndrome Cushing reaction Cushing reflex Cushing triad Cyclic antidepressant poisoning Detomidine Digitalis Diltiazem Diphenhydramine Distichiasis - heart and vasculature anomalies - sinus bradycardia Donepezil Doxepin Drowning Emery-Dreifuss muscular dystrophy Enema Fetal distress Gamma-hydroxybutyric acid Gastric lavage Glyceryl trinitrate Grayanotoxin Hantavirus pulmonary syndrome Hashimoto's thyroiditis Heat exhaustion Hellebore Holt-Oram syndrome Hydrocodone Hydroxyethyl starchSpeedball (drug) Hypercalcemia Hyperkalemia Hypokalemia Hypothermia Hypothyroidism Ibuprofen Increased intracranial pressure Isosorbide dinitrate

Ivabradine Legionella pneumonia Levobetaxolol Levobupivacaine Lidocaine Lithium Malnutrition Mammalian diving reflex Medetomidine Mefloquine Mepivacaine Methacholine Methyldopa Morphine Moxonidine Mycoplasma pneumonia Nadolol Nalbuphine Nalmefene Necrotizing enterocolitis Neonatal lupus erythematosus Neurocardiogenic syncope Neurogenic shock Obstructive jaundice Oculocardiac reflex Opioid poisoning Oxymorphone Phenobarbital Phenylephrine Phenytoin Pilocarpine Pneumothorax Propafenone Propranolol Pulseless ventricular tachycardia Quinidine Radiocontrast toxicity Raised Intracranial pressure Rapid sequence induction Reserpine Right bundle branch block Ropivacaine Second degree AV block Sedatives Septic shock Sick sinus syndrome Sinoatrial block Skull fracture Sleep ST elevation myocardial infarction complications Subarachanoid hemorrhage Sulpiride Suxamethonium chloride Tacrine Theobromine poisoning Timolol Trazodone Trypanosoma cruzi Tularaemia Typhoid fever Uncaria tomentosa Vagal episode Vasa previa Vasovagal syncope Vertebral subluxation Xylazine