First degree AV block causes: Difference between revisions

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electrolyte disturbances
electrolyte disturbances
[[drugs]]; [[calcium channel blockers]], [[beta-blockers]], [[digitalis]],[[cardiac glycosides]], [[cholinesterase inhibitor|cholinesterase inhibitors]].
[[drugs]]; [[calcium channel blockers]], [[beta-blockers]], [[digitalis]],[[cardiac glycosides]], [[cholinesterase inhibitor|cholinesterase inhibitors]], ** [[Quinidine]] and [[Procainamide]] may produce slight prolongation of the PR,
* Normal variants of [[PR prolongation]]
* Normal variants of [[PR prolongation]]
* [[Vagal maneuvers]]
* [[Vagal maneuvers]]
Line 39: Line 39:
* [[hypertension]]
* [[hypertension]]


** [[Acute rheumatic fever]]
* [[Acute rheumatic fever]]
** [[Dilated cardiomyopathy]]  
* [[Dilated cardiomyopathy]]  
** [[HCM]]: 3% of patients with [[HCM]] will develop heart block
* [[HCM]]: 3% of patients with [[HCM]] will develop heart block
** [[Myocarditis]]
* [[Myocarditis]]
** [[SLE]]
* [[SLE]]
** Tumors, primary and secondary
* Tumors, primary and secondary


* Valvular Heart Disease
* Valvular Heart Disease
** Calcific [[aortic stenosis]] may be accompanied by chronic partial or complete AV block
* Calcific [[aortic stenosis]]
** There is an extension of the calcification to involve the main bundle or its bifurcation, resulting in degeneration and necrosis of the conduction tissue
* Rheumatic mitral valve disease
** May also occur in rheumatic mitral valve disease, but is less common
** Occasionally, massive calcification of the mitral annulus as an aging process may cause [[AV block]]
*  May also be seen in [[bacterial endocarditis]], especially of the [[aortic valve]]
*  May also be seen in [[bacterial endocarditis]], especially of the [[aortic valve]]
* [[Ebstein's anomaly]]  may be associated with first-degree AV block.
* [[Ebstein's anomaly]]
 
  [[transposition of the great vessels]], [[ASD]]s and [[Ebstein's anomaly]]
* Drugs
[[VSD]],
** [[Digoxin]] is one of the most common causes of reversible [[AV block]]
[[tetralogy of Fallot]]
*** The ventricular response rate is more rapid than that due to organic lesions, and increased automaticity of the AV junctional pacemaker may be responsible.
[[endocardial cushion defect]].
** [[Quinidine]] and [[Procainamide]] may produce slight prolongation of the PR
** [[Beta blocker|β blockers]] may cause [[AV block]]
** [[Diltiazem]] and [[verapamil]] may cause AV conduction delay and [[PR interval]] prolongation
 
First degree heart block is not an absolute contraindication for the use of these drugs but caution should be maintained while using these drugs in patients with first degree block, as exposure to these drugs increases the risk of developing a higher grade block.
 
* Congenital
** Occurs in the absence of other evidence of organic heart disease
** Site is usually proximal to the bifurcation of the [[His bundle]], most often in the [[AV node]]
** Narrow [[QRS]] with a rate > 40 beats per minute
** Frequently seen in those with corrected [[transposition of the great vessels]], and occasionally in [[ASD]]s and [[Ebstein's anomaly]]
 
* Trauma
** May be induced during open heart surgery in the area of AV conduction tissue
** Seen in patients operated on for the correction of [[VSD]], [[tetralogy of Fallot]], and [[endocardial cushion defect]].
** May be due to [[edema]], transient ischemia, or actual disruption of the conduction tissue. The block may therefore be permanent or transient.
** Also reported with both penetrating and non-penetrating trauma of the chest


===Causes by Organ System===
===Causes by Organ System===

Revision as of 17:08, 21 August 2013

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Raviteja Guddeti, M.B.B.S. [3] Synonyms and keywords:

Overview

Causes

Life Threatening Causes

Life-threatening conditions can result in death or permanent disability within 24 hours if left untreated.

Common Causes

Enhanced vagal tone in athletes

electrolyte disturbances drugs; calcium channel blockers, beta-blockers, digitalis,cardiac glycosides, cholinesterase inhibitors, ** Quinidine and Procainamide may produce slight prolongation of the PR,

  • Idiopathic bilateral bundle branch fibrosis and the heart block is called primary heart block
  • Hypertension
  • Chronic AV block in patients with HTN is thought to be due to CAD or sclerosis of the left side of the cardiac skeleton exacerbated by
  • hypertension
transposition of the great vessels, ASDs and Ebstein's anomaly
VSD,

tetralogy of Fallot endocardial cushion defect.

Causes by Organ System

Cardiovascular AV nodal disease, Myocarditis, Acute myocardial infarction (especially acute inferior MI), Hypertension, Acute rheumatic fever, Dilated cardiomyopathy, HCM, Myocarditis, Valvular heart disease, Transposition of the great vessels, ASDs, Ebstein's anomaly, VSD, Tetralogy of Fallot, Endocardial cushion defect, Lev's disease
Chemical / poisoning No underlying causes
Dermatologic No underlying causes
Drug Side Effect Calcium channel blockers, Beta-blockers, Digitalis, Cardiac glycosides, Cholinesterase inhibitors, Quinidine, Procainamide, Disopyramide, Flecainide, Encainide, Propafenone, Amiodarone, Sotalol, Dofetilide, Ibutilide, Magnesium
Ear Nose Throat No underlying causes
Endocrine No underlying causes
Environmental No underlying causes
Gastroenterologic Hemochromatosis
Genetic No underlying causes
Hematologic No underlying causes
Iatrogenic No underlying causes
Infectious Disease Acute rheumatic fever, Chagas disease, Diphtheria, Lyme disease, Myocarditis, Tuberculosis
Musculoskeletal / Ortho Ankylosing spondylitis, Muscular dystrophy
Neurologic No underlying causes
Nutritional / Metabolic No underlying causes
Obstetric/Gynecologic No underlying causes
Oncologic No underlying causes
Opthalmologic No underlying causes
Overdose / Toxicity No underlying causes
Psychiatric No underlying causes
Pulmonary Sarcoidosis
Renal / Electrolyte No underlying causes
Rheum / Immune / Allergy Ankylosing spondylitis, Dermatomyositis, Scleroderma, SLE, Rheumatoid arthritis
Sexual No underlying causes
Trauma No underlying causes
Urologic No underlying causes
Dental No underlying causes
Miscellaneous Amyloidosis, Enhanced vagal tone (for example in athletes), Normal variants

Causes in Alphabetical Order

References


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