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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/09/03 08:43:30」(JST)

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Cardioversion is a medical procedure by which an abnormally fast heart rate (tachycardia) or cardiac arrhythmia is converted to a normal rhythm, using electricity or drugs. Synchronized electrical cardioversion uses a therapeutic dose of electric current to the heart, at a specific moment in the cardiac cycle. Pharmacologic cardioversion, also called chemical cardioversion, uses antiarrhythmia medication instead of an electrical shock.^[1]

Synchronized electrical cardioversion[edit source | edit]

To perform synchronized electrical cardioversion two electrode pads are used (or, alternatively, the traditional hand-held "paddles"), each comprising a metallic plate which is faced with a saline based conductive gel. The pads are placed on the chest of the patient, or one is placed on the chest and one on the back. These are connected by cables to a machine which has the combined functions of an ECG display screen and the electrical function of a defibrillator. A synchronizing function (either manually operated or automatic) allows the cardioverter to deliver a reversion shock, by way of the pads, of a selected amount of electric current over a predefined number of milliseconds at the optimal moment in the cardiac cycle which corresponds to the R wave of the QRS complex on the ECG. Timing the shock to the R wave prevents the delivery of the shock during the vulnerable period (or relative refractory period) of the cardiac cycle, which could induce ventricular fibrillation. If the patient is conscious, various drugs are often used to help sedate the patient and make the procedure more tolerable. However, if the patient is hemodynamically unstable or unconscious, the shock is given immediately upon confirmation of the arrhythmia. When synchronized electrical cardioversion is performed as an elective procedure, the shocks can be performed in conjunction with drug therapy until sinus rhythm is attained. After the procedure, the patient is monitored to ensure stability of the sinus rhythm.

Synchronized electrical cardioversion is used to treat hemodynamically significant supraventricular (or narrow complex) tachycardias, including atrial fibrillation and atrial flutter. It is also used in the emergent treatment of wide complex tachycardias, including ventricular tachycardia, when a pulse is present. Pulseless ventricular tachycardia and ventricular fibrillation are treated with unsynchronized shocks referred to as defibrillation. Electrical therapy is inappropriate for sinus tachycardia, which should always be a part of the differential diagnosis.

Pharmacological cardioversion[edit source | edit]

Various antiarrhythmic agents can be used to return the heart to normal sinus rhythm. Pharmacological cardioversion is an especially good option in patients with fibrillation of recent onset. Drugs that are effective at maintaining normal rhythm after electric cardioversion, can also be used for pharmacological cardioversion. Drugs like amiodarone, diltiazem, verapamil and metoprolol are frequently given before cardioversion to decrease the heart rate, stabilize the patient and increase the chance that cardioversion is successful. There are various classes of agents that are most effective for pharmacological cardioversion.

Class I agents are sodium (Na) channel blockers (which slow conduction by blocking the Na+ channel) and are divided into 3 subclasses a, b and c. Class Ia slows phase 0 depolarization in the ventricles and increases the absolute refractory period. Procainamide, quinidine and disopyramide are Class Ia agents. Class 1b drugs shorten phase 3 repolarization. They include lidocaine, mexiletine and phenytoin. Class Ic greatly slow phase 0 depolarization in the ventricles (however unlike 1a have no effect on the refractory period). Flecainide, moricizine and propafenone are Class Ic agents.

Class II agents are beta blockers which inhibit SA and AV node depolarization and slow heart rate. They also decrease cardiac oxygen demand and can prevent cardiac remodeling. Not all beta blockers are the same, some are cardio selective (affecting only beta 1 receptors) while others are non-selective (affecting beta 1 and 2 receptors). Beta blockers that target the beta-1 receptor are called cardio selective because beta-1 is responsible for increasing heart rate; hence a beta blocker will slow the heart rate.

Class III agents (prolong repolarization by blocking outward K+ current): amiodarone and sotalol are effective class III agents. Ibutilide is another Class III agent but has a different mechanism of action (acts to promote influx of sodium through slow-sodium channels). It has been shown to be effective in acute cardioversion of recent-onset atrial fibrillation and atrial flutter.

Class IV drugs are calcium (Ca) channel blockers. They work by inhibiting the action potential of the SA and AV nodes.

If the patient is stable, adenosine may be administered first, as the medicine performs a sort of "chemical cardioversion" and may stabilize the heart and let it resume normal function on its own without using electricity.

References[edit source | edit]

^ Shea, Julie B.; William H. Maisel (2002). "Cardioversion". Circulation 106 (22): e176–8. doi:10.1161/01.CIR.0000040586.24302.B9. PMID 12451016.

External links[edit source | edit]

Cardioversion from the National Institutes of Health
Pharmacological Cardioversion from the American Academy of Family Physicians
Synchronized Electrical Cardioversion from eMedicine Online
Cardioversion from the Heart Rhythm Society

UpToDate Contents

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1. 特定の不整脈に対する除細動 cardioversion for specific arrhythmias
2. 心房細動：洞調律への心臓除細動 atrial fibrillation cardioversion to sinus rhythm
3. カルディオバージョンおよび除細動の基本原則と手技 basic principles and technique of cardioversion and defibrillation
4. 小児における除細動およびカルディオバージョン（自動体外式除細動期を含む） defibrillation and cardioversion in children including automated external defibrillation
5. 心房細動および洞調律への心臓除細動の血行動態的影響 hemodynamic consequences of atrial fibrillation and cardioversion to sinus rhythm

English Journal

Arrhythmias during and after zoledronic acid infusion patients with bone metastasis.

Yazici O, Aksoy S, Ucar O, Ozdemir N, Demir M, Sendur MA, Arik Z, Yaman S, Eren T, Uncu D, Zengin N.SourceDepartment of Medical Oncology, Ankara Numune Education and Research Hospital, 06100, Sihhiye, Ankara, Turkey, drozanyazici@gmail.com.
Medical oncology (Northwood, London, England).Med Oncol.2013 Sep;30(3):609. doi: 10.1007/s12032-013-0609-5. Epub 2013 May 21.
Zoledronic acid (ZA) is one of the important bisphosphonates which is widely used in bone metastatic cancer and osteoporotic patients. In a few studies, it has been reported that treatment with bisphosphonates was associated with an increased risk of atrial fibrillation. We aimed to evaluate the arr
PMID 23690271

C-reactive protein and P-wave in hypertensive patients after conversion of atrial fibrillation.

Mazza A, Bendini MG, Cristofori M, Leggio M, Nardi S, Giordano A, De Cristofaro R, Giordano G.SourceaCardiology Division, Santa Maria della Stella Hospital, Orvieto bEpidemiologic and Bio-Statistics Unit, AUSL Terni 4, Terni cCardiovascular Department, Cardiac Rehabilitation Operative Unit (S.I.), San Filippo Neri Hospital, Rome dCardiology Division, Santa Maria Hospital, Terni eNephrology Unit, Santa Maria della Stella Hospital, Orvieto, Italy.
Journal of cardiovascular medicine (Hagerstown, Md.).J Cardiovasc Med (Hagerstown).2013 Jul;14(7):520-7. doi: 10.2459/JCM.0b013e32835224b5.
AIMS: P maximum/P dispersion and high-sensitivity C-reactive protein (hs-C-reactive protein) have been proposed as useful markers for predicting the history and recurrence of atrial fibrillation. We tested the association between hs-C-reactive protein and maximum P-wave duration (P maximum)/P-wave d
PMID 22441219

Japanese Journal

Associations Between Renal Function, Atrial Substrate Properties and Outcome of Catheter Ablation in Patients With Paroxysmal Atrial Fibrillation

CHAO Tze-Fan,LIN Yenn-Jiang,CHANG Shih-Lin,LO Li-Wei,HU Yu-Feng,TUAN Ta-Chuan,SUENARI Kazuyoshi,LI Cheng-Hung,CHEN Shih-Ann
Circulation journal : official journal of the Japanese Circulation Society 75(10), 2326-2332, 2011-09-25
… Background: Renal dysfunction was reported to be associated with a higher recurrence rate after electric cardioversion of atrial fibrillation (AF). …
NAID 10029459182

Efficacy and Safety of Bepridil for Patients with Persistent Atrial Fibrillation after Failed Electrical Cardioversion

EGAMI Yasuyuki,NISHINO Masami,TANIIKE Masayuki,MAKINO Nobuhiko,KATO Hiroyasu,SHUTTA Ryu,TANOUCHI Jun,YAMADA Yoshio
Journal of arrhythmia 27(2), 131-136, 2011-04-25
NAID 10029598937

Related Pictures

★リンクテーブル★

リンク元	「心房細動」「電気的除細動」「心臓除細動」「電気除細動」
拡張検索	「synchronized cardioversion」

「心房細動」

Cardioversion
	Intervention
ICD-9-CM	99.6
MeSH	D004554

　　[★]

英: atrial fibrillation, AF, AFIB
関: 心房粗動、心室細動

定義

心房細動は心房が高頻度に、しかも同期せずに興奮する状態である。その結果、心房は心室に血液を送るための律動的な収縮を行えなくなり、また心室の興奮も不規則となる。 (参考2)

分類

参考2

発作性心房細動

自然停止する心房細動

持続性心房細動

停止に薬物などを必要とするものを持続性心房細動

孤立性心房細動

基礎心疾患を認めず，高血圧もない症例に出現した心房細動

永続性心房細動

完全房室ブロックを伴う心房細動(EAB 135)

原因

原発性

加齢によるもの

他の疾患に続発

若年性の心房細動は要注意

心房細動を合併しやすい病態

医学大事典

虚血性心疾患、高血圧症、リウマチ性心疾患、心筋症、呼吸器疾患、甲状腺機能亢進症、高齢者心房中隔欠損症、WPW症候群など

心房負荷で僧帽弁狭窄症を来しやすい

甲状腺機能亢進症

危険因子 QB.C-410

高齢者(65歳以上)
脳卒中の既往
高血圧
心不全
心房・心室拡大

症状

頻拍に因る：動悸、胸部圧迫感
拍出量低下による：(器質的心疾患のある場合)心不全
心房収縮低下による：心房内血栓形成　→　血栓塞栓症

血栓塞栓症は心房細動の時と心房細動から洞調律に復帰させるときに起こりやすい。

心電図

着目する誘導：P波 = II誘導、f波 = V1誘導
1. f波の出現(400-700/分(EAB.160), 350-600/分(PHD.295))←多数興奮旋回 multiple reentry
2. P波の欠如
3. RR間隔が不整　←　f波が時々心室に伝わるため

絶対性不整脈

[show details]

治療

QB.C-410

血行動態が不安定：電気的除細動
血行動態が安定　：2-3週間抗凝固療法を行ってから薬物的な除細動Class Ia(APD↑), Class Ic(APD±)

48-72時間以内に新規発症した心房細動では抗凝固療法不要
経食道心エコーにより左房内血栓を認めなければ、除細動施行。
慢性経過(6ヶ月程度)した慢性心房細動では除細動を行っても再発する率が高いので、除細動の適応にはならない？？？？

概要

薬物療法と抗凝固療法を施行する
electrical direct-current cardioversionによる洞調律の回復は、頻脈の時にすべき(心房の興奮が心室に伝導しているとき)
カテーテルアブレーションは症状があって、かつ他の内科的治療法が奏効しない特に行う
外科治療はMaze手術がある

薬物治療

心室への興奮の伝達を抑制：Class II, class IV, or digitalis
除細動　　　　　　　　　：Class Ia(APD↑), Class Ic(APD±), Class III

薬物治療 (不整脈薬物治療に関するガイドライン Guidelines for Drug Treatment of Arrhythmias (JCS 2004))

心機能の低下	第一選択	第二選択
正常*	Naチャネル阻害薬	Na チャネル遮断薬
	slow drug	intermediate
	ジソピラミド	プロカインアミド
	シベンゾリン	キニジン
	ピルジカイニド	プロパフェノン
		アプリンジン
軽度*	Na チャネル遮断薬
	intermediate
	プロカインアミド
	キニジン
	プロパフェノン
	アプリンジン
中度以上	Na チャネル遮断薬
	intermediate
	プロカインアミド
	キニジン
	アプリンジン