Torsades de pointes

トルサード・ド・ポアンツ

WordNet

1. mark with diacritics; "point the letter"
2. a very small circular shape; "a row of points"; "draw lines between the dots" (同)dot
3. an instant of time; "at that point I had to leave" (同)point in time
4. repair the joints of bricks; "point a chimney" (同)repoint
5. a V shape; "the cannibals teeth were filed to sharp points" (同)tip, peak
6. a linear unit used to measure the size of type; approximately 1/72 inch
7. a style in speech or writing that arrests attention and has a penetrating or convincing quality or effect
8. one percent of the total principal of a loan; it is paid at the time the loan is made and is independent of the interest on the loan
9. the unit of counting in scoring a game or contest; "he scored 20 points in the first half"; "a touchdown counts 6 points"
10. the gun muzzles direction; "he held me up at the point of a gun" (同)gunpoint
11. the property of a shape that tapers to a sharp tip (同)pointedness
12. a wall socket (同)power_point
13. an outstanding characteristic; "his acting was one of the high points of the movie" (同)spot
14. a distinguishing or individuating characteristic; "he knows my bad points as well as my good points"
15. sharp end; "he stuck the point of the knife into a tree"; "he broke the point of his pencil"
16. a V-shaped mark at one end of an arrow pointer; "the point of the arrow was due north" (同)head
17. a brief version of the essential meaning of something; "get to the point"; "he missed the point of the joke"; "life has lost its point"
18. a geometric element that has position but no extension; "a point is defined by its coordinates"
19. a promontory extending out into a large body of water; "they sailed south around the point"
20. the object of an activity; "what is the point of discussing it?"
21. the precise location of something; a spatially limited location; "she walked to a point where she could survey the whole street"
22. be positionable in a specified manner; "The gun points with ease"
23. indicate the presence of (game) by standing and pointing with the muzzle; "the dog pointed the dead duck"
24. mark (a psalm text) to indicate the points at which the music changes
25. mark (Hebrew words) with diacritics
26. a legal document signed and sealed and delivered to effect a transfer of property and to show the legal right to possess it; "he signed the deed"; "he kept the title to his car in the glove compartment" (同)deed of conveyance, title
27. go `ding dong, like a bell (同)dong, dingdong
28. a ringing sound

PrepTutorEJDIC

1. 〈C〉(針・鉛筆・剣などの)『とがった先』,(…の)先端《+『of』+『名』》 / 〈C〉岬(みさき) / 〈C〉(小数点・句読点などの)点 / 〈C〉(図形上の)点 / 〈C〉(ある特定の)『地点』(spot),場所(place) / 〈C〉(計器の目盛りなどの)『点』,『度』 / 〈C〉時点,瞬間 / 〈C〉《単数形で》(物語・議論などの)『要点』,核心《+『of』(『in』)+『名』》 / 〈U〉(…の)『目的』,『意義』,ねらっている点《+『of』(『in』)+『名』(do『ing』)》 / 〈C〉(全体の中の)個々の項目,細目(item),細部(detail) / 〈C〉特徴(characteristic),特質(trait) / 〈C〉(競技・学校の成績などの)得点 / 〈C〉ポイント(活字の大きさの単位;約1/72インチの大きさ) / (…に)〈銃・指など〉‘を'『向ける』《+『名』+『at』(『to, toward』)+『名』》 / …‘に'『指し示す』《point+名+to+名…に…をさし示す》 / …‘の'先をとがらせる,‘に'先を付ける / …‘に'点を打つ;…‘に'小数点を付ける;…‘に'句読点を付ける / 〈猟犬が〉〈獲物〉‘を'指し示す / (…を)(指などで)『示す』,指し示す《+『at』(『to, toward』)+『名』(do『ing』)》 / 〈猟犬が〉獲物の位置を示す
2. 『行為』,行動 / (正式の)捺印証書,権利書 / …'を'証書を作製して譲渡する
3. 〈鐘など〉‘を'ガンガン鳴らす / 〈鐘などが〉ガンガン鳴る / (鐘の)ガンガン鳴る音
4. (おもに人称代名詞・固有名詞(人名),thereの後で)had, wouldの短縮形 / (疑問文でwhere,what,whenの後で)didの短縮形;Where'd he go?=Where did he go?
5. Delaware

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/30 23:09:54」(JST)

wiki en

[Wiki en表示]

Torsades de pointes
12-lead ECG of Torsades de Pointes (TdP) in a 56-year-old white female with Hypokalemia (2.4 mmol/L) and Hypomagnesemia (1.6 mg/dL.)
Classification and external resources
Specialty	Cardiology
DiseasesDB	29252
eMedicine	med/2286 emerg/596
Patient UK	Torsades de pointes
MeSH	D016171

Torsades de pointes or torsade de pointes (TdP or simply torsade(s)) (French: [tɔʁsad də pwɛ̃t], translated as "twisting of the spikes"), is a specific type of abnormal heart rhythm that can potentially lead to sudden cardiac death. It is a polymorphic ventricular tachycardia that exhibits distinct characteristics on the electrocardiogram (ECG). It was described by Dessertenne in 1966.

Signs and symptoms

Most episodes revert spontaneously to a normal sinus rhythm. Other possible outcomes include palpitations, dizziness, lightheadedness (short episodes), fainting (longer episodes), and sudden cardiac death.

Causes

Common causes for torsades de pointes include diarrhea, low blood magnesium and low blood potassium. It is commonly seen in malnourished individuals and chronic alcoholics. Certain combinations of drugs resulting in drug interactions may contribute: decreasing the metabolism of a medication causing QT elongation such as clarithromycin (Biaxin), levofloxacin, or haloperidol (Haldol), taken concomitantly with a specific cytochrome P450 inhibitor like fluoxetine (Prozac), cimetidine (Tagamet); foods like grapefruit will result in higher than normal doses of the medication responsible for the QT elongation. Since these specific drugs worsen the elongation of the QT wave in a dose-dependent manner, inhibition of drug metabolism raises the risks of developing a malignant torsades de pointes arrhythmia.

Prescription drug interactions

TdP as a prescription drug side effect has been a major liability and reason for withdrawal of medications from the marketplace. Examples include amiodarone, methadone, lithium, chloroquine, erythromycin, amphetamine, ephedrine, pseudoephedrine, methylphenidate and phenothiazines. It can also be the side effect of some antiarrhythmic medications such as sotalol, procainamide and quinidine. The gastrokinetic drug cisapride (Propulsid) was withdrawn from the US market in 2000 after such interactions led to deaths caused by long QT syndrome-induced torsades de pointes. To correct the prolonged QT interval, magnesium IV 2gm will help effectively block calcium flow as well as prevent recurrent Torsade de Pointes.

In September 2011 (subsequently updated in March 2012 and February 2013), the FDA issued a warning concerning increased incidence of QT elongation with doses of the antidepressant Celexa (citalopram) above 40 mg per day, which is considered the maximum allowable dosage, increasing the risk of Torsades. However, the study, "Evaluation of the FDA Warning Against Prescribing Citalopram at Doses Exceeding 40 mg" reported no increased risk of abnormal arrhythmias thus questioning the merit of FDA warning.

Risk factors

The following is a list of factors associated with an increased tendency toward torsades de pointes:

Lead II ECG showing torsades being shocked by an implantable cardioverter-defibrillator back to the patient's baseline cardiac rhythm.

• Hypokalemia (low blood potassium)
• Hypomagnesemia (low blood magnesium)
• Hypocalcemia (low blood calcium)
• Bradycardia (slow heartbeat)
• Heart failure
• Left ventricular hypertrophy
• Hypothermia
• Subarachnoid hemorrhage
• Hypothyroidism

Diagnosis

The ECG tracing in torsades demonstrates a polymorphic ventricular tachycardia with a characteristic illusion of a twisting of the QRS complex around the isoelectric baseline (peaks which are at first pointing up are seen to be pointing down for subsequent "beats" when looking at ECG traces of the "heartbeat"). It is hemodynamically unstable and causes a sudden drop in arterial blood pressure, leading to dizziness and fainting. Depending on their cause, most individual episodes of torsades de pointes revert to normal sinus rhythm within a few seconds, but may also persist and possibly degenerate into ventricular fibrillation, which will lead to sudden death in the absence of prompt medical intervention. Torsades de pointes is associated with long QT syndrome, a condition whereby prolonged QT intervals are visible on the ECG. Long QT intervals predispose the patient to an R-on-T phenomenon, where the R wave representing ventricular depolarization occurs during the relative refractory period at the end of repolarization (represented by the latter half of the T-wave). An R-on-T can initiate torsades. Sometimes pathologic T-U waves may be seen in the ECG before the initiation of torsades.

A "short-coupled variant of torsade de pointes", which presents without long QT syndrome, was also described in 1994.

• Drastic rotation of the heart's electrical axis
• Prolonged QT interval (LQTS) - may not be present in the short-coupled variant of torsade de pointes
• Preceded by long and short RR-intervals - not present in the short-coupled variant of torsade de pointes
• Triggered by a premature ventricular contraction (R-on-T PVC)

Treatment

Treatment is directed at withdrawal of the offending agent, infusion of magnesium sulfate, antiarrhythmic drugs, and electrical therapy such as a temporary pacemaker as needed.

Because of the polymorphic nature of torsades de pointes, synchronized cardioversion may not be possible, and the patient may require an unsynchronized shock (or defibrillation).

History

The phenomenon was originally described in a French medical journal by Dessertenne in 1966, when he observed this cardiac rhythm disorder in an 80-year-old female patient with complete intermittent atrioventricular block. In coining the term, he referred his colleagues to the "Dictionnaire Le Robert," a bilingual French English dictionary, of which his wife had just given him a copy. Here "torsade" is defined as (a)a bundle of threads twisted in a helix or spiral, for ornamental purposes, as in an Aran sweater; (b) long hair twisted together, or (c) an ornamental motif as seen on architectural columns.

The singular and plural forms (torsade de pointes and torsades de pointes) have both often been used. The question of whether either one is "correct" and the other "incorrect" has repeatedly arisen. Among major medical dictionaries, one enters only the plural form, another enters the plural form as the headword but lists the singular as a variant, and another enters the singular form as the headword and gives a usage comment saying that the plural is not preferred. One group of physicians suggests that it would make sense to use the singular form as the general entity name (whether comprising a single or repeated episodes) and that one might best reserve the plural form for describing repeated twistings during a single episode. Regarding the natural language variation, they conclude good-naturedly, "Wasn't it the French who coined the term 'vive la difference?'"

References

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

• 1. 後天性ＱＴ延長症候群 acquired long qt syndrome
• 2. 先天性QT延長症候群の臨床的特徴 clinical features of congenital long qt syndrome
• 3. 頻脈性不整脈の急性期マネージメントの概要 overview of the acute management of tachyarrhythmias
• 4. 心血管疾患における低マグネシウム血症の意義 significance of hypomagnesemia in cardiovascular disease
• 5. 頭部白癬 tinea capitis

English Journal

• Magnesium-Essentials for Anesthesiologists.

• Herroeder S, Schonherr ME, De Hert SG, Hollmann MW.
• Anesthesiology.2011 Apr;114(4):971-993.
• PMID 21364460

• Acquired long QT syndrome from stress cardiomyopathy is associated with ventricular arrhythmias and torsades de pointes.

• Madias C, Fitzgibbons TP, Alsheikh-Ali AA, Bouchard JL, Kalsmith B, Garlitski AC, Tighe DA, Estes NA 3rd, Aurigemma GP, Link MS.
• Heart rhythm : the official journal of the Heart Rhythm Society.2011 Apr;8(4):555-61. Epub 2010 Dec 10.
• PMID 21146632

• BeKm-1, a Peptide Inhibitor of Human ether-a-go-go-Related Gene Potassium Currents, Prolongs QTc Intervals in Isolated Rabbit Heart.

• Qu Y, Fang M, Gao B, Chui RW, Vargas HM.
• The Journal of pharmacology and experimental therapeutics.2011 Apr;337(1):2-8. Epub 2010 Dec 23.
• PMID 21205913

Japanese Journal

• 心室頻拍/torsades de pointes (特集 興奮の伝わり方と波形を結びつけて理解する 心電図セミナー) -- (頻脈性心室性不整脈のモニター心電図の特徴)

• 松井 由美恵
• 臨床看護 37(5), 682-686, 2011-04
• NAID 40018760456

• Microminipig, a Non-rodent Experimental Animal Optimized for Life Science Research:In Vivo Proarrhythmia Models of Drug-Induced Long QT Syndrome: Development of Chronic Atrioventricular Block Model of Microminipig

• Sugiyama Atsushi,Nakamura Yuji,Akie Yasuki,Saito Hiroyuki,Izumi Yasukatsu,Yamazaki Hiroshi,Kaneko Naoki,Itoh Katzuhiko
• Journal of Pharmacological Sciences 115(2), 122-126, 2011
• A new in vivo proarrhythmia model of drug-induced long QT syndrome was developed using the Microminipig, an incredibly small minipig established by Fuji Micra Inc. (Shizuoka). The atrioventricular (AV …
• NAID 130000439934

Related Links

• トルサデポアン・Torsade de Pointes/心室頻拍/QT延長症候群//

そのうち、心拍数（心臓の収縮回数）200～250 回/分で心電図上QRS 群の上下の揺れが 変化する心室頻拍をトルサド・ド・ポアン（Torsades de pointes）といい、QT 時間の 延長を伴っていることが多い。 症状. QT 時間の延長、不整脈. 原因となる主な薬剤 ...

Related Pictures

---

★リンクテーブル★

リンク元	「QT延長症候群」「トルサード・ド・ポアンツ」「多形性心室頻拍」「TdP」
関連記事	「point」「DE」「torsades de pointes」

「QT延長症候群」

　　[★]

英

long QT syndrome, QT prolongation syndrome

関

先天性QT延長症候群、後天性QT延長症候群、QT延長、トルサード・ド・ポアント。QT間隔

症状

• しばしば心室性不整脈の特殊な型であるTorsades de pointesを起こし、心不全、そして死に至ることがある (SP.537)
• 心室頻拍、心室細動を呈し、さらに失神発作や突然死に至る

定義

• QT時間が延長する
• 心電図で観測されたQT間隔を心拍数により補正したQT_cが0.46秒を超える場合(SP.537)

先天性

• 原因遺伝子は多く同定されているが、LQT1～3で全体の9割を占めている。出生2000に対して1の割合で認められるという。

疾患名	遺伝形式		遺伝子座	遺伝子	蛋白	表現型	心電図上の特徴
Romano-Ward症候群	常染色体優性	LQT1	11p15.5	KCNQ1	カリウムチャネル(KVLQT1)		幅広いT波
		LQT2	7q35-36	KCNH2	カリウムチャネル(HERG)		ノッチを伴う平低T波
		LQT3	3p21	SCN5A	ナトリウムチャネル(hH1)		ST部分の長いT波
		LQT4	4q25-27	ANK2	アンキリンB
		LQT5	21q22.1-q22.2	KCNE1	カリウムチャネル(minK)
		LQT6	21q22.1-q22.2	KCNE2	カリウムチャネル(MiRP1)
Jervell and Lange-Nielsen症候群	常染色体劣性	JLN1	11p15.5	KCNQ1	カリウムチャネル(KVLQT1)	難聴
		JLN2	21p22.1-q22.2	KCNE1	カリウムチャネル(minK)	難聴

後天性

薬剤性

• 抗不整脈薬

• I群：キニジン、ジソピラミド、プロカインアミド、フレカイニドなど
• III群：ソタロール、ニフェカラント、アミオダロンなど

• 抗生物質(エリスロマイシン、ST合剤など)
• 抗真菌薬(イトラコナゾールなど)
• 抗アレルギー薬(テルフェナジン、アステミゾールなど)
• 抗高脂血症薬(プロブコールなど)
• 抗精神病薬(ハロペリドール、クロルプロマジンなど)
• 三環系抗うつ薬(イミプラミン、アミトリプチリンなど)
• 抗癌剤(ドキソルビシンなど)

徐脈

• 房室ブロック、洞機能不全症候群

電解質異常

• 低カリウム血症、低マグネシウム血症

疾患

• クモ膜下出血、頭蓋内出血、ストレス心筋症、神経性食欲不振症

治療

Acquired long QT syndrome: Clinical manifestations, diagnosis, and management

急性期治療

• 血行動態が不安定：低血圧、意識レベル低下、胸痛、心不全

除細動

• 血行動態が安定：

マグネシウム点滴、電解質補正、原因薬剤の除去

上記に加え心拍数コントロールのためにオーバードライブ心房ペーシング±イソプロテレノール(心房心拍数を上げてQTを短縮させる効果がある)の点滴もオプション

「トルサード・ド・ポアンツ」

　　[★]

仏

Torsades de pointes, torsades de pointes, torsade de pointes

同

トルサード・ド・ポアンツ、トルサード・ド・ポアン、倒錯型心室頻拍、倒錯性心室頻拍、多形性心室頻拍 polymorphic ventricular tachycardia

関

QT延長症候群

[show details]

トルサード・ド・ポアン : 87 件
トルサード・ド・ポアント : 60 件
トルサード・ド・ポアンツ : 81 件
トルサードドポアント : 60 件

概念

• 多形性心室頻拍であって、非発作時にはQT延長を伴うものである。
• 心電図上、多形性心室頻拍を示し、QRSがベースラインに対して反転した波形で周期的に変動する。

疫学

SQ.549

• 性差：女性に多い
• 好発年齢：35-50歳

病因

• QT延長症

• 先天性QT延長症候群：
• 後天性QT延長症候群：

病態

• 心拍数減少により失神・痙攣を来す。
• 短時間のうちに頻拍が停止し、回復することもまれならずある。

治療

• QT延長が原因であればMgを静注。
• QT延長の原因によって次の治療を行う。

• 先天性QT延長症候群：β遮断薬
• 後天性QT延長症候群：心室ペーシング(一時的ペーシング)

YN.C-49

• 原因の除去、硫酸マグネシウム→メキシレチン
• 薬物療法無効であれば体外式ペーシング。

予防

• 先天性QT延長症候群：β遮断薬、ICD
• 後天性QT延長症候群：QT延長の治療

参考

• 1. 不整脈薬物治療に関するガイドライン（2009年改訂版）

[display]http://www.j-circ.or.jp/guideline/pdf/JCS2009_kodama_h.pdf

「多形性心室頻拍」

　　[★]

英

polymorphic ventricular tachycardia polymorphic VT, polymorphous ventricular tachycardia

関

トルサード・ド・ポアンツ、不整脈、心室頻拍

概念

• 多形性心室頻拍は頻拍中のQRS波形が刻々と変化し、QRS波形が基線を中心にしてねじれているように見える。多くは非持続性で自然停止するが、時に心室細動に移行する。

分類

• QT延長を伴う：Torsades de pointes TdP　　→　　QT時間の延長を伴い、T波に続く心室性期外収縮によって誘発され、QRS波形が刻々と変化する多型性心室頻拍で、QRS波の振幅が基線の周りを捻じれるように変動する。

• 先天性QT延長症候群

• Jervell and Lange-Nielsen症候群
• Romano-Ward症候群

• 後天性QT延長症候群：薬剤(抗不整脈薬(Ia群、III群)、非心臓薬(向精神薬、抗生剤、抗アレルギー薬など)など)が多い。

• QT延長伴っていない

• 心疾患有り：虚血、心不全、ショックなどの心機能低下に伴って起こる場合が多い
• 心疾患なし：　→　特発性多形性心室頻拍

• Brugada症候群：胸部誘導(V1-V3)のST上昇が特徴。若年-壮年男性の突然死の原因
• カテコラミン誘発多形性心室頻拍：感情の高まり、運動、イソプロテレノールで誘発
• QT短縮症候群(SQTS)
• 明らかな誘因や心電図学的特徴が認められない特発性多形性心室頻拍・心室細動

参考

• 1. 不整脈薬物治療に関するガイドライン（2009年改訂版）

[display]http://www.j-circ.or.jp/guideline/pdf/JCS2009_kodama_h.pdf

「TdP」

　　[★] トルサード・ド・ポアンツ, Torsades de pointes

「point」

　　[★]

• vt.
• vi.

• 指さす、示す(at,to)
• (ある方向に)向いている(to,toward)
• 傾向にある(to)

• n.

関

dictate、direct、dot、indicate、indication、instruct、instruction、spot

　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　 　

「DE」

　　[★] 線量当量 dose equivalent 　

「torsades de pointes」

　　[★] トルサード・ド・ポアンツ