WordNet

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"
toward or on the left; also used figuratively; "he looked right and left"; "the political party has moved left"
a turn toward the side of the body that is on the north when the person is facing east; "take a left at the corner"
the hand that is on the left side of the body; "jab with your left" (同)left_hand
those who support varying degrees of social or political or economic change designed to promote the public welfare (同)left wing
location near or direction toward the left side; i.e. the side to the north when a person or object faces east; "she stood on the left"
intended for the left hand; "I rarely lose a left-hand glove" (同)left-hand
being or located on or directed toward the side of the body to the west when facing north; "my left hand"; "left center field"; "the left bank of a river is bank on your left side when you are facing downstream"
of or belonging to the political or intellectual left
of or near the head end or toward the front plane of a body
earlier in time (同)prior
completely obstructed or closed off; "the storm was responsible for many blocked roads and bridges"; "the drain was plugged" (同)plugged
closed to traffic; "the repaving results in many blocked streets" (同)out of use
a group of countries in special alliance (同)axis

PrepTutorEJDIC

(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
leaveの過去・過去分詞
《名詞の前にのみ用いて》『左の』,左方の / 《しばしばl-》(政治上の)左翼の,左派の,革新派の / 左に,左方に / 《通例 the ~》『左』,左方,左側 / 《しばしばthe L-》左翼の政党(団体),左派 / 〈U〉(野球で)左翼,レフト(left field);〈C〉左翼手(left fielder) / 〈C〉(ボクシングで)左手打ち
(場所などが)前の,前部の;(…より)前に位置する《+『to』+『名』》 / (時・事件などが)以前の,先の;(…より)前の《+『to』+『名』》
ブロック,圏(地理・共通の利害・政治・経済上の目的などのために団結した団体・国家などの結合体)

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/18 16:05:30」(JST)

wiki en

Left anterior fascicular block, sometimes abbreviated LAFB, is a cardiac condition,^[1]^[2] distinguished from left bundle branch block.

It is caused by only the anterior half of the left bundle branch being defective. It is manifested on the ECG by left axis deviation.

It is much more common than left posterior fascicular block.

Characteristics

Normal activation of the left ventricle proceeds down the left bundle branch, which consist of three fascicles, the left anterior fascicle, the left posterior fascicle, and the septal fascicle. The posterior fascicle supplies the posterior and inferoposterior walls of the left ventricle, the anterior fascicle supplies the upper and anterior parts of the left ventricle and the septal fascicle supplies the septal wall with innervation. Left Anterior Fascicular Block (LAFB), which is also known as Left Anterior Hemiblock (LAHB), occurs when a cardiac impulse spreads first through the left posterior fascicle, causing a delay in activation of the anterior and upper parts of the left ventricle. Although there is a delay or block in activation of the left anterior fascicle there is still preservation of initial left to right septal activation as well as preservation of the inferior activation of the left ventricle (preservation of septal Q waves in I and aVL and predominantly negative QRS complex in leads II, III, and aVF). The delayed and unopposed activation of the remainder of the left ventricle now results in a shift in the QRS axis leftward and superiorly, causing marked left axis deviation. This delayed activation also results in a widening of the QRS complex, although not to the extent of a complete LBBB.

Criteria

Abnormal left axis deviation^[3] (usually between –45° and –60°)^[4]
qR complex in the lateral limb leads (I and aVL)
rS pattern in the inferior leads (II, III, and aVF)
Delayed intrinsicoid deflection in lead aVL (> 0.045 s)

It is important not to call LAFB in the setting of a prior inferior wall myocardial infarction which may also demonstrate left axis deviation due to the initial forces (Q wave in a Qr complex) in leads II, III, and aVF.

Effects of LAFB on Diagnosing Infarctions and Left Ventricular Hypertrophy

LAHB may be a cause of poor R wave progression across the precordium causing a pseudoinfarction pattern mimicking an anteroseptal infarction. It also makes the electrocardiographic diagnosis of LVH more complicated, because both may cause a large R wave in lead aVL. Therefore to call LVH on an EKG in the setting of an LAHB you should see the presence of a “strain” pattern when you are relying on limb lead criteria to diagnose LVH. _____

Clinical Significance

It can be seen in approximately 4% of cases of acute myocardial infarction
- It is the most common type of intraventricular conduction defect seen in acute anterior myocardial infarction, and the left anterior descending artery is usually the culprit vessel.
- It can be seen with acute inferior wall myocardial infarction.
It is also associated with hypertensive heart disease, aortic valvular disease, cardiomyopathies, and degenerative fibrotic disease of the cardiac skeleton.

References

^ Rebuzzi AG, Loperfido F, Biasucci LM (July 1985). "Transient Q waves followed by left anterior fascicular block during exercise". Br Heart J 54 (1): 107–9. doi:10.1136/hrt.54.1.107. PMC 481860. PMID 4015909.
^ Chandrashekhar Y, Kalita HC, Anand IS (January 1991). "Left anterior fascicular block: an ischaemic response during treadmill testing". Br Heart J 65 (1): 51–2. doi:10.1136/hrt.65.1.51. PMC 1024464. PMID 1899584.
^ Horwitz S, Lupi E, Hayes J, Frishman W, Cárdenas M, Killip T (September 1975). "Electrocardiographic criteria for the diagnosis of left anterior fascicular block. Left axis deviation and delayed intraventricular conduction". Chest 68 (3): 317–20. doi:10.1378/chest.68.3.317. PMID 1157535.
^ "Conduction Blocks 2006 KCUMB". Retrieved 2009-01-20.

External links

ECG course notes at the university of Utah

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. 左脚前枝ブロック left anterior fascicular block
2. 心電図チュートリアル：心室内ブロック ecg tutorial intraventricular block
3. 慢性二枝ブロックの経過および治療 course and treatment of chronic bifascicular block
4. 心室内伝導遅延への基本的アプローチ basic approach to delayed intraventricular conduction
5. 非同期性興奮と早期興奮の一般原則 general principles of asynchronous activation and preexcitation

English Journal

Brugada syndrome (BS) and syncope: A complex therapeutic issue.

Merante A, Gareri P, Bonacci E, Russo G, Castagna A, Lacava R, Marigliano NM, Gualtieri U, Condito AM, Ruotolo G.SourceSOC Geriatric Unit, "Pugliese-Ciaccio" Hospital, via Madonna dei Cieli, I-88100 Catanzaro, Italy.
Archives of gerontology and geriatrics.Arch Gerontol Geriatr.2012 Nov;55(3):706-8. Epub 2011 Nov 23.
A 66 year-old man was brought to the emergency room (ER) for syncope and sphincter incontinence; syncope duration was about 15min. Similar short duration episodes had been referred by his relatives during the last months, following small traumas; no seizures had been registered. Patient told he was
PMID 22115873

Japanese Journal

Estimation of Left Intra-Ventricular Activation Alterations and Conduction Delay Due to Left Anterior Fascicular Block Using a Novel Magnetocardiographic Approach with 3 Directional Recordings

Journal of Arrhythmia 27(Supplement), PJ3_048-PJ3_048, 2011
NAID 130002130330

シロスタゾールにより心拍数の増加と日常生活動作能力の向上を認めた洞機能不全症候群の一例

日本老年医学会雑誌 36(8), 561-564, 1999-08-25
NAID 10008485316

Chronic Chagas' Heart Disease in a Japanease-Brazilian Traveler.

Japanese Heart Journal 40(3), 375-382, 1999
NAID 130000070270

Related Pictures

★リンクテーブル★

リンク元	「左脚前枝ブロック」「LAFB」
関連記事	「block」「fascicular block」「left」「anterior」「fascicular」

「左脚前枝ブロック」

Left anterior fascicular block
Classification and external resources
Specialty	cardiology
ICD-10	I44.4

　　[★]

英: left anterior fascicular block LAFB, left anterior hemiblock LAH LAHB
同: 左脚前枝ヘミブロック
関: 心室内伝導障害、左脚ブロック、左脚後枝ブロック、束枝ブロック。右脚ブロック

概念

心室内刺激伝導路の左脚は前枝と後枝に分かれている。
左脚前枝は左室前壁を左方に向かい、左脚後枝は後側壁を下方に向かう。
左脚前枝はもっぱら左冠動脈前下行枝から血流を得ている。

心電図所見

心電図の読み方パーフェクトマニュアル.99

電気軸：左軸偏位(-30ﾟ～-80ﾟ)
I,aVLがqR型(通常RaVL>RI)
II,III,aVFがrS型(SIII>SaVF>SII)

左脚前枝の走行

心電図の読み方パーフェクトマニュアル.99

左室前壁を左方に向かう

興奮の伝達

心電図の読み方パーフェクトマニュアル.99

後枝を下り、前枝を逆行性に左上方に伝達
QRS時間は延長せず、QRS軸は初期に下方、後期には左上方となる　→　-30～-80(左軸変位)

左脚前枝ブロックと左脚後枝ブロック心電図パーフェクトマニュアルp.99

		左脚前枝ブロック	左脚後枝ブロック
走行		左室前壁を左方に向かう	後側壁を下降する
走行		大動脈弁の近くを走行
形状		より細長い
栄養		左冠動脈前下行枝のみ	左冠動脈回旋枝、右冠動脈
疾患との関連		解剖学的特性より効果病変に巻き込まれやすく、障害されやすい。また、血流のバックアップに乏しく虚血に弱い
心電図	QRS	ほとんど延長しない	ほとんど延長しない
	電気軸	左軸偏位(-30°～-80°)	右軸偏位(+110°以上)
	側壁誘導	qR	rS
	下壁誘導	rS	qR