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a three-dimensional shape with six square or rectangular sides (同)cube
(computer science) a sector or group of sectors that function as the smallest data unit permitted; "since blocks are often defined as a single sector, the terms `block and `sector are sometimes used interchangeably"
support, secure, or raise with a block; "block a plate for printing"; "block the wheels of a car"
a solid piece of something (usually having flat rectangular sides); "the pyramids were built with large stone blocks"
housing in a large building that is divided into separate units; "there is a block of classrooms in the west wing"
a rectangular area in a city surrounded by streets and usually containing several buildings; "he lives in the next block" (同)city block
an inability to remember or think of something you normally can do; often caused by emotional tension; "I knew his name perfectly well but I had a temporary block" (同)mental_block
a number or quantity of related things dealt with as a unit; "he reserved a large block of seats"; "he held a large block of the companys stock"
interrupt the normal function of by means of anesthesia; "block a nerve"; "block a muscle"
run on a block system; "block trains"
shape by using a block; "Block a hat"; "block a garment"
shape into a block or blocks; "block the graphs so one can see the results clearly"
stamp or emboss a title or design on a book with a block; "block the book cover"
a part of a forked or branching shape; "he broke off one of the branches" (同)leg, ramification
divide into two or more branches so as to form a fork; "The road forks" (同)ramify, fork, furcate, separate
a division of a stem, or secondary stem arising from the main stem of a plant
a division of some larger or more complex organization; "a branch of Congress"; "botany is a branch of biology"; "the Germanic branch of Indo-European languages" (同)subdivision, arm
a stream or river connected to a larger one
make into a bundle; "he bundled up his few possessions" (同)bundle_up, roll_up
sleep fully clothed in the same bed with ones betrothed (同)practice bundling
a package of several things tied together for carrying or storing (同)sheaf
the act of binding something into a bundle
the act of shoving hastily; "she complained about bundling the children off to school"
a onetime custom during courtship of unmarried couples occupying the same bed without undressing
broken husks of the seeds of cereal grains that are separated from the flour by sifting
food prepared from the husks of cereal grains

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(木・石などの,通例平らな面のある)『かたまり』 / 《米》(四団を街路に囲まれた)『区画』,街区 / 街区の1辺の距離(一般に40メートル前後) / 《英》ブロック(アパート・事務所・商店などに区切られている大きな建物) / 『妨害物』,障害物(obstacle);(障害によって生じた)停滞,渋滞 / 台木,台(まないた・肉切り台・まき割り台・せり売り台・帽子の木型など);《the~》炭頭台 / (特にアメリカンフットボールで)ブロック(相手の選手の突進を阻止する) / 滑車(pulley) / (座席券・株券などの)一組《+『of』+『名』》 / 〈通路など〉'を'『ふさぐ』,〈通行・進行など〉'を'妨げる / 〈帽子など〉の型取りをする / (特にアメリカンフットボールで)〈相手選手の突進〉'を'ブロックする;(ボクシングで)〈相手のパンチ〉'を'ブロックする
『枝』 / 『支流』,支脈,支線;分家 / 『支店』,『支部』,支局 / (学問の)『部門』,分科 / 枝を出す,枝を広げる / (川・道・鉄道などが)分岐する
(…の)『束』,『包み』,巻いたもの(旅行者の荷物など)《+『of』+『名』》 / …'を'包みにする,束にする / (…に)…'を'ごっちゃに投げ込む《+『名』+『into』+『名』》 / 荷物をまとめてさっさと出て行く《+『off』(『out』,『away』)》
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Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/10/28 12:12:26」(JST)

wiki en

A bundle branch block is a defect of the bundle branches or fascicles in the electrical conduction system of the heart.

Anatomy and physiology

The heart's electrical activity begins in the sinoatrial node (the heart's natural pacemaker), which is situated on the upper right atrium. The impulse travels next through the left and right atria and summates at the atrioventricular node. From the AV node the electrical impulse travels down the bundle of His and divides into the right and left bundle branches. The right bundle branch contains one fascicle. The left bundle branch subdivides into two fascicles: the left anterior fascicle and the left posterior fascicle. Other sources divide the left bundle branch into three fascicles: the left anterior, the left posterior, and the left septal fascicle. The thicker left posterior fascicle bifurcates, with one fascicle being in the septal aspect. Ultimately, the fascicles divide into millions of Purkinje fibres, which in turn interdigitise with individual cardiac myocytes, allowing for rapid, coordinated, and synchronous physiologic depolarization of the ventricles.

Bundle branch blocks

When a bundle branch or fascicle becomes injured (by underlying heart disease, myocardial infarction, or cardiac surgery), it may cease to conduct electrical impulses appropriately. This results in altered pathways for ventricular depolarization. Since the electrical impulse can no longer use the preferred pathway across the bundle branch, it may move instead through muscle fibers in a way that both slows the electrical movement and changes the directional propagation of the impulses. As a result, there is a loss of ventricular synchrony, ventricular depolarization is prolonged, and there may be a corresponding drop in cardiac output. When heart failure is present, a specialized pacemaker may be used to resynchronize the ventricles. In theory a pacemaker like this will shorten the QRS interval, thus bringing the timing of contraction of the left and right ventricles closer together and slightly increasing the ejection fraction.

Types of bundle branch blocks

Image showing the ECG characteristics of a right bundle branch block and a left bundle branch block. In both cases, the late portion of the widened QRS complex arises from an anomalously conducted depolarization impulse. The direction of this delayed depolarization vector differs based on the structure that is blocked; the impulse travels anterior toward the right ventricle in RBBB and lateral toward the left ventricle in LBBB.

Depending on the anatomical location of the defect which leads to a bundle branch block, the blocks are further classified into:

Right bundle branch block
Left bundle branch block

The left bundle branch block can be further sub classified into:

Left anterior fascicular block. In this case only the anterior half of the left bundle branch (fascicle) is involved
Left posterior fascicular block. Only the posterior part of the left bundle branch is involved

Other classifications of bundle branch blocks are;

Bifascicular block. This is a combination of right bundle branch block (RBBB) and either left anterior fascicular block (LAFB) or left posterior fascicular block (LPFB)
Trifascicular block. This is a combination of right bundle branch block with either left anterior fascicular block or left posterior fascicular block together with a first degree AV block

Diagnosis and treatment

A bundle branch block can be diagnosed when the duration of the QRS complex on the ECG exceeds 120 ms. A right bundle branch block typically causes prolongation of the last part of the QRS complex, and may shift the heart's electrical axis slightly to the right. The ECG will show a terminal R wave in lead V1 and a slurred S wave in lead I. Left bundle branch block widens the entire QRS, and in most cases shifts the heart's electrical axis to the left. The ECG will show a QS or rS complex in lead V1 and a monophasic R wave in lead I. Another normal finding with bundle branch block is appropriate T wave discordance. In other words, the T wave will be deflected opposite the terminal deflection of the QRS complex. Bundle branch block, especially left bundle branch block, can lead to cardiac dyssynchrony. The simultaneous occurrence of left and right bundle branch block leads to total AV block.

Some people with bundle branch blocks are born with this condition. Many other acquire it as a consequence of heart disease. People with bundle branch blocks may still be quite active, and may have nothing more remarkable than an abnormal appearance to their ECG. However, when bundle blocks are complex and diffuse in the bundle systems, or associated with additional and significant ventricular muscle damage, they may be a sign of serious underlying heart disease. In more severe cases, a pacemaker may be required to restore an optimal electrical supply to the heart muscle.

References

Cecil Textbook of Medicine. W.B. Sanders. 2004. Chapters 50; 58.
Rakel: Textbook of Family Practice, 6th ed., 2002. W.B. Saunders Company. pp. 699–732.

UpToDate Contents

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1. 右脚ブロック right bundle branch block
2. 左脚ブロック left bundle branch block
3. 脚ブロックまたはペーシング調律存在下での心筋梗塞の心電図による診断 electrocardiographic diagnosis of myocardial infarction in the presence of bundle branch block or a paced rhythm
4. 左脚ブロックまたはペースメーカーによる心室リズムの患者における負荷試験 stress testing in patients with left bundle branch block or a paced ventricular rhythm
5. 心室内伝導遅延への基本的アプローチ basic approach to delayed intraventricular conduction

English Journal

High-sensitivity troponin level pre-catheterization predicts adverse cardiovascular outcomes after primary angioplasty for ST-elevation myocardial infarction.

Wang TK1, Snow TA, Chen Y, Rostom H, White JM, Stewart JT, Webster MW, Ruygrok PN, Watson T, White HD.
European heart journal. Acute cardiovascular care.Eur Heart J Acute Cardiovasc Care.2014 Jun 1;3(2):118-25. doi: 10.1177/2048872614527006. Epub 2014 Feb 27.
BACKGROUND: Cardiac troponins are the preferred biomarkers for diagnosing myocardial infarction (MI). High-sensitivity troponin T (hs-TnT) assays have increased sensitivity and enable more rapid diagnosis of infarction. We assessed the prognostic utility of admission hs-TnT to detect outcomes after
PMID 24576774

Sites of latest mechanical activation as assessed by SPECT myocardial perfusion imaging in ischemic and dilated cardiomyopathy patients with LBBB.

Lin X1, Xu H, Zhao X, Chen J.
European journal of nuclear medicine and molecular imaging.Eur J Nucl Med Mol Imaging.2014 Jun;41(6):1232-9. doi: 10.1007/s00259-014-2718-6. Epub 2014 Feb 28.
OBJECTIVE: Sites of latest mechanical activation (SOLA) have been recognized as optimal left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT). This study was aimed to investigate SOLA in ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM) patients with left bund
PMID 24577952

Impact of right-ventricular apical pacing on the optimal left-ventricular lead positions measured by phase analysis of SPECT myocardial perfusion imaging.

Hung GU1, Huang JL, Lin WY, Tsai SC, Wang KY, Chen SA, Lloyd MS, Chen J.
European journal of nuclear medicine and molecular imaging.Eur J Nucl Med Mol Imaging.2014 Jun;41(6):1224-31. doi: 10.1007/s00259-014-2693-y. Epub 2014 Feb 28.
PURPOSE: The use of SPECT phase analysis to optimize left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT) was performed at baseline, but CRT works as simultaneous right ventricular (RV) and LV pacing. The aim of this study was to assess the impact of RV apical (RVA) pacin
PMID 24577949

Japanese Journal

Recruitment of Complete Right Bundle Branch Block by Permanent Para-Hisian Pacing

Kataoka Tatsuhiko,Miyazaki Shinsuke,Kaseno Kenichi,Hasegawa Kanae,Amaya Naoki,Tada Hiroshi
International Heart Journal 60(1), 189-192, 2019
… <p>His-bundle pacing has recently emerged as a means to maintain a physiological ventricular activation and eliminate the risk of pacing-induced myopathy associated with traditional right ventricular pacing. …
NAID 130007557123

Recruitment of Complete Right Bundle Branch Block by Permanent Para-Hisian Pacing

Kataoka Tatsuhiko,Miyazaki Shinsuke,Kaseno Kenichi,Hasegawa Kanae,Amaya Naoki,Tada Hiroshi
International Heart Journal, 2019
… <p>His-bundle pacing has recently emerged as a means to maintain a physiological ventricular activation and eliminate the risk of pacing-induced myopathy associated with traditional right ventricular pacing. …
NAID 130007519963

どのような重症心不全症例にCRTを勧めるか? (特集循環器疾患におけるディベート)

絹川弘一郎
Heart view 22(10), 994-998, 2018-10
NAID 40021705752

Related Pictures

★リンクテーブル★

リンク元	「脚ブロック」「BBB」
拡張検索	「complete right bundle branch block」「incomplete left bundle branch block」「left bundle branch block」「right bundle-branch block」
関連記事	「block」「branch」「branched」「bundle」「branching」

「脚ブロック」

Bundle branch block
	ECG showing a bundle branch block
Classification and external resources
Specialty	cardiology
ICD-10	I44.4-I44.7, I45
ICD-9-CM	426.3-426.5
DiseasesDB	7352 11620
eMedicine	ped/2501 ped/2500
MeSH	D002037