副収縮
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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/06/19 23:22:20」(JST)
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| Parasystole |
| Classification and external resources |
| MeSH |
D017574 |
Parasystole is a kind of arrhythmia caused by the presence and function of a secondary pacemaker in the heart, which works in parallel with the SA node. Parasystolic pacemakers are protected from depolarization by the SA node by some kind of entrance block. This block can be complete or incomplete.
Parasystolic pacemakers can exist in both the atrium or the ventricle. Atrial parasystolia are characterized by narrow QRS complexes
Two forms of ventricular parasystole have been described in the literature, fixed parasystole and modulated parasystole. Fixed ventricular parasystole occurs when an ectopic pacemaker is protected by entrance block, and thus its activity is completely independent from the sinus pacemaker activity. Hence, the ectopic pacemaker is expected to fire at a fixed rate. Therefore, on ECG, the coupling intervals of the manifest ectopic beats will wander through the basic cycle of the sinus rhythm. Accordingly, the traditional electrocardiographic criteria used to recognize the fixed form of parasystole are:
- the presence of variable coupling intervals of the manifest ectopic beats;
- inter-ectopic intervals that are simple multiples of a common denominator;
- fusion beats.
According to the modulated parasystole hypothesis, rigid constancy of a pacemaker might be expected if the entrance block were complete, but if there is an escape route available for the emergence of ectopic activity, then clearly there must be an effective ionic communication, not complete insulation, between the two tissues. If there is an electrical communication between the two, then the depolarization of the surrounding ventricle may influence the ectopic pacemaker. That influence will be electrotonic; depolarization of the surrounding field will induce a partial depolarization of the pacemaker cells. Therefore, appropriate diagnosis of modulated parasystole relies upon the construction of a “phase response curve” as theoretical evidence of modulation of the ectopic pacemaker cycle length by the electrotonic activity generated by the sinus discharges across the area of protection. In this case, the timing of the arrival of the electronic stimulus will serve to delay or advance the subsequent pacemaker activation. In this case, the coupling intervals between the manifest ectopic and sinus discharges will be either fixed or variable, depending on the cycle length relations between the two pacemakers.
See also
External links
- ventricular parasystole
- atrial parasystole
- Cardiovascular disease: heart disease
- Circulatory system pathology
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| Ischaemic |
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Coronary disease
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- Coronary artery disease (CAD)
- Coronary artery aneurysm
- Coronary artery dissection
- Coronary thrombosis
- Coronary vasospasm
- Myocardial bridge
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Active ischemia
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- Angina pectoris
- Prinzmetal's angina
- Stable angina
- Acute coronary syndrome
- Myocardial infarction
- Unstable angina
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Sequelae
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- hours
- Hibernating myocardium
- Myocardial stunning
- days
- weeks
- Aneurysm of heart / Ventricular aneurysm
- Dressler's syndrome
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| Layers |
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Pericardium
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- Pericarditis
- Acute
- Chronic / Constrictive
- Pericardial effusion
- Cardiac tamponade
- Hemopericardium
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Myocardium
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- Myocarditis
- Cardiomyopathy: Dilated (Alcoholic), Hypertrophic, and Restrictive
- Loeffler endocarditis
- Cardiac amyloidosis
- Endocardial fibroelastosis
- Arrhythmogenic right ventricular dysplasia
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Endocardium /
valves
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Endocarditis
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- infective endocarditis
- Subacute bacterial endocarditis
- non-infective endocarditis
- Libman–Sacks endocarditis
- Nonbacterial thrombotic endocarditis
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Valves
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- mitral
- regurgitation
- prolapse
- stenosis
- aortic
- tricuspid
- pulmonary
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Conduction /
arrhythmia |
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Bradycardia
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- Sinus bradycardia
- Sick sinus syndrome
- Heart block: Sinoatrial
- AV
- Intraventricular
- Bundle branch block
- Right
- Left
- Left anterior fascicle
- Left posterior fascicle
- Bifascicular
- Trifascicular
- Adams–Stokes syndrome
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Tachycardia
(paroxysmal and sinus)
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Supraventricular
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- Atrial
- Junctional
- AV nodal reentrant
- Junctional ectopic
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Ventricular
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- Accelerated idioventricular rhythm
- Catecholaminergic polymorphic
- Torsades de pointes
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Premature contraction
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Pre-excitation syndrome
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- Lown–Ganong–Levine
- Wolff–Parkinson–White
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Flutter / fibrillation
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- Atrial flutter
- Ventricular flutter
- Atrial fibrillation
- Ventricular fibrillation
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Pacemaker
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- Ectopic pacemaker / Ectopic beat
- Multifocal atrial tachycardia
- Pacemaker syndrome
- Parasystole
- Wandering pacemaker
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Long QT syndrome
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- Andersen–Tawil
- Jervell and Lange-Nielsen
- Romano–Ward
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Cardiac arrest
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- Sudden cardiac death
- Asystole
- Pulseless electrical activity
- Sinoatrial arrest
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Other / ungrouped
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- hexaxial reference system
- Right axis deviation
- Left axis deviation
- QT
- T
- ST
- Osborn wave
- ST elevation
- ST depression
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| Cardiomegaly |
- Ventricular hypertrophy
- Left
- Right / Cor pulmonale
- Atrial enlargement
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| Other |
- Cardiac fibrosis
- Heart failure
- Diastolic heart failure
- Cardiac asthma
- Rheumatic fever
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noco/cong/tumr, sysi/epon, injr
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proc, drug (C1A/1B/1C/1D), blte
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UpToDate Contents
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English Journal
- Irregular coronary sinus parasystole due to second-degree entrance block.
- Kinoshita S, Katoh T.
- Journal of cardiovascular medicine (Hagerstown, Md.).J Cardiovasc Med (Hagerstown).2012 Sep;13(9):600-2.
- PMID 20935573
- Premature ventricular contractions originating from the left ventricular septum: results of radiofrequency catheter ablation in twenty patients.
- Jia L, Yue-Chun L, Kang-Ting J, Na-Dan Z, Jia-Xuan L, Wen-Wu Z, Peng-Lin Y, Ji-Fei T, Jia-Feng L.SourceDepartment of Cardiology, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou 325000, China.
- BMC cardiovascular disorders.BMC Cardiovasc Disord.2011 Jun 2;11:27.
- BACKGROUND: RFCA has been established as an effective and curative therapy for severely symptomatic PVC from the outflow tract in structurally normal hearts. However, it is unknown whether PVCs originating from the left ventricular septum, are effectively eliminated by RFCA. This study aimed to inve
- PMID 21635765
Japanese Journal
- Catheter Ablation of Ventricular Parasystole
- NAKAHARA Shiro,TORATANI Noritaka,TAKAYANAGI Kan
- Journal of arrhythmia 27(1), 83-86, 2011-01-25
- NAID 10029598709
- 心収縮性の低下および心室副収縮が認められたフェレットの1例
- 竹村 直行,宮川 優一,戸田 典子,広瀬 昶
- 日本獣医師会雑誌 = Journal of the Japan Veterinary Medical Association 61(5), 386-389, 2008-05-20
- 約1カ月前からの運動不耐性に加え、1週間前からの断続的な発咳を主訴にフェレット（去勢雄、5歳、体重1.25kg）が日本獣医生命科学大学付属動物医療センターに来院した。身体検査では、頻脈および不整脈が聴取された。心電図検査では心室副収縮が記録された。胸部X線検査では、心陰影の拡大は軽度であったが、Mモード心エコー法により、拡張期左室内径の拡大および左室短径短縮率の低下がみられた。テモカプリルおよびア …
- NAID 10025574098
Related Links
- parasystole /para·sys·to·le/ (-sis´tah-le) a cardiac irregularity attributed to the interaction of two foci independently initiating cardiac impulses at different rates. par·a·sys·to·le (păr′ə-sĭs′tə-lē) n. An arrhythmia characterized by a second ...
- parasystole par·a·sys·to·le (pār'ə-sĭs'tə-lē) n. An arrhythmia characterized by a second automatic rhythm existing simultaneously with normal sinus rhythm.
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