Paroxysmal AV block overview: Difference between revisions
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*Atrioventricular block may be classified anatomically by the site of block, usually divided into atrioventricular nodal, intra-Hisian (within the His bundle itself), and infra-Hisian (below the His bundle). | *Atrioventricular block may be classified anatomically by the site of block, usually divided into atrioventricular nodal, intra-Hisian (within the His bundle itself), and infra-Hisian (below the His bundle). | ||
*Paroxysmal AV block is defined as a delayed escape rhythm which repetitively blocks conduction from the atria to the ventricles, thereby causing [[syncope]], conduction defects such as [[asystole]] and [[sudden cardiac death]]. | *Paroxysmal AV block is defined as a delayed escape rhythm which repetitively blocks conduction from the atria to the ventricles, thereby causing [[syncope]], conduction defects such as [[asystole]] and [[sudden cardiac death]]. | ||
*It may or may not be associated with Phase 3 or Phase 4 conduction defects. | *It may or may not be associated with Phase 3 or Phase 4 conduction defects. | ||
*It may be due to an increased [[vagal]] tone, innately low [[adenosine]] levels or an intrinsic conduction defect, all of which lead to different [[ECG]] presentations. | *It may be due to an increased [[vagal]] tone, innately low [[adenosine]] levels or an intrinsic conduction defect, all of which lead to different [[ECG]] presentations. | ||
*Insufficient data is available regarding the exact [[etiology]], diagnostic study of choice and treatment of paroxysmal AV blocks. | *Insufficient data is available regarding the exact [[etiology]], diagnostic study of choice and treatment of paroxysmal AV blocks. | ||
*It can be thought of more as a disease of exclusion. However,efforts must be made to have a standardized approach to such patients. | *It can be thought of more as a [[disease]] of [[exclusion]]. However,efforts must be made to have a [[standardized]] approach to such patients. | ||
*The site of block may be clinically important and can be determined by invasive EPS when not apparent from the ECG and clinical circumstances. | *The site of [[block]] may be [[clinically]] important and can be determined by invasive [[EPS]] when not apparent from the [[ECG]] and [[clinical]] circumstances. | ||
*In general, atrioventricular block at the atrioventricular nodal level is associated with slower progression, a faster and more reliable atrioventricular junctional escape mechanism, and greater responsiveness to autonomic manipulation such as atropine, isoproterenol, and epinephrine administration. <ref name="pmid30412710">{{cite journal| author=Kusumoto FM, Schoenfeld MH, Barrett C, Edgerton JR, Ellenbogen KA, Gold MR | display-authors=etal| title=2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society. | journal=J Am Coll Cardiol | year= 2019 | volume= 74 | issue= 7 | pages= 932-987 | pmid=30412710 | doi=10.1016/j.jacc.2018.10.043 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30412710 }} </ref> | *In general, [[atrioventricular block]] at the [[atrioventricular nodal]] level is associated with slower progression, a faster and more reliable atrioventricular [[junctional escape mechanism]], and greater responsiveness to [[autonomic]] manipulation such as [[atropine]], [[isoproterenol]], and [[epinephrine]] administration. <ref name="pmid30412710">{{cite journal| author=Kusumoto FM, Schoenfeld MH, Barrett C, Edgerton JR, Ellenbogen KA, Gold MR | display-authors=etal| title=2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society. | journal=J Am Coll Cardiol | year= 2019 | volume= 74 | issue= 7 | pages= 932-987 | pmid=30412710 | doi=10.1016/j.jacc.2018.10.043 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30412710 }} </ref> | ||
**In contrast, atrioventricular block within or below the His bundle may progress rapidly and unexpectedly, is associated with a slower and more unpredictable ventricular escape mechanism, will not respond to atropine but will sometimes improve with catecholamines. <ref name="pmid30412710">{{cite journal| author=Kusumoto FM, Schoenfeld MH, Barrett C, Edgerton JR, Ellenbogen KA, Gold MR | display-authors=etal| title=2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society. | journal=J Am Coll Cardiol | year= 2019 | volume= 74 | issue= 7 | pages= 932-987 | pmid=30412710 | doi=10.1016/j.jacc.2018.10.043 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30412710 }} </ref> | **In contrast, [[atrioventricular block]] within or below the [[His bundle]] may progress rapidly and unexpectedly, is associated with a slower and more unpredictable [[ventricular escape mechanism]], will not respond to [[atropine]] but will sometimes improve with [[catecholamines]]. <ref name="pmid30412710">{{cite journal| author=Kusumoto FM, Schoenfeld MH, Barrett C, Edgerton JR, Ellenbogen KA, Gold MR | display-authors=etal| title=2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society. | journal=J Am Coll Cardiol | year= 2019 | volume= 74 | issue= 7 | pages= 932-987 | pmid=30412710 | doi=10.1016/j.jacc.2018.10.043 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30412710 }} </ref> | ||
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Revision as of 08:18, 26 June 2020
- Atrioventricular block may be classified anatomically by the site of block, usually divided into atrioventricular nodal, intra-Hisian (within the His bundle itself), and infra-Hisian (below the His bundle).
- Paroxysmal AV block is defined as a delayed escape rhythm which repetitively blocks conduction from the atria to the ventricles, thereby causing syncope, conduction defects such as asystole and sudden cardiac death.
- It may or may not be associated with Phase 3 or Phase 4 conduction defects.
- It may be due to an increased vagal tone, innately low adenosine levels or an intrinsic conduction defect, all of which lead to different ECG presentations.
- Insufficient data is available regarding the exact etiology, diagnostic study of choice and treatment of paroxysmal AV blocks.
- It can be thought of more as a disease of exclusion. However,efforts must be made to have a standardized approach to such patients.
- The site of block may be clinically important and can be determined by invasive EPS when not apparent from the ECG and clinical circumstances.
- In general, atrioventricular block at the atrioventricular nodal level is associated with slower progression, a faster and more reliable atrioventricular junctional escape mechanism, and greater responsiveness to autonomic manipulation such as atropine, isoproterenol, and epinephrine administration. [1]
- In contrast, atrioventricular block within or below the His bundle may progress rapidly and unexpectedly, is associated with a slower and more unpredictable ventricular escape mechanism, will not respond to atropine but will sometimes improve with catecholamines. [1]
- ↑ 1.0 1.1 Kusumoto FM, Schoenfeld MH, Barrett C, Edgerton JR, Ellenbogen KA, Gold MR; et al. (2019). "2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society". J Am Coll Cardiol. 74 (7): 932–987. doi:10.1016/j.jacc.2018.10.043. PMID 30412710.