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"
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
the act of obstructing or deflecting someones movements (同)block

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
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）』「2016/02/15 15:13:02」(JST)

wiki en

The initial impulse in a heart is usually formed in the Sinoatrial (SA) node and carried through the atria, down the internodal atrial pathways, and to the Atrioventricular (AV) node. In normal conduction, the impulse would travel across the “bundle of His” (AV bundle), down the bundle branches, and into the Purkinje fibers. This would depolarize the ventricles and cause them to contract.

In an SA block, the electrical impulse is delayed or blocked on the way to the atria, thus delaying the atrial beat.^[1] This is different from an AV block, which occurs in the AV node and delays ventricular depolarization. SA blocks are categorized into three classes based on the length of the delay.

Types

In a first degree sinoatrial block, there is a lag between the time that the SA node fires and actual depolarization of the atria. This rhythm is not recognizable on an ECG strip because a strip does not denote when the SA node fires. It can be detected only during an electrophysiology study when a small wire is placed against the SA node from within the heart and the electrical impulses can be recorded as they leave the p-cells in the centre of the node [ see pacemaker potential ], followed by observing a delay in the onset of the p wave on the ECG.

Second degree SA blocks are broken down into two subcategories just like AV blocks are:

The first is a second degree type I, or Wenckebach block.^{[citation needed]} This rhythm is irregular, and the R-R interval gets progressively smaller, while the P-R interval remains constant, until a QRS segment is dropped. Note that this is quite different from the Wenckebach AV block, in which the PR interval gets progressively longer, before the dropped QRS segment. The pause of a second degree type I is less than twice the shortest R-R interval and is not a multiple of the P-R interval. The cause is a gradual lengthening of conduction time from the SA node to the atria. The p-cells in the centre of the node produce the rhythm at a regular rate, but their conduction across the node to where it meets atrial tissue is where the slowing occurs.

A second degree type II, or sinus exit block, is a regular rhythm that may be normal or slow. It is followed by a pause that is a multiple of the P-R interval. Conduction across the SA node is normal until the time of the pause when it is blocked.

A third degree sinoatrial block looks very similar to a sinus arrest. However, a sinus arrest is caused by a failure to form impulses. A third degree block is caused by failure to conduct them. The rhythm is irregular and either normal or slow. It is followed by a long pause that is not a multiple of the P-R interval. The pause ends with a P wave, instead of a junctional escape beat the way a sinus arrest would.

Symptoms and treatment

Sinoatrial blocks are typically well-tolerated. They are not as serious as an AV block and most often do not require treatment. In some people, they can cause fainting, altered mental status, chest pain, hypoperfusion, and signs of shock. They can also lead to cessation of the SA node and more serious dysrhythmias. Emergency treatment, if deemed necessary, consists of administration of atropine sulfate or transcutaneous pacing.

References

^ Medical Dictionary: Sinoatrial heart block

Bledsoe, Porter, Cherry (2009). Paramedic Care; Principles and Practice. New Jersey: Brady. ISBN 978-0-13-513702-4.

Schilling McCann, Judith (2009). Cardiovascular Care Made Incredibly Easy. Pennsylvania: Lippincott Williams and Wilkins. ISBN 978-0-7817-8824-3.

UpToDate Contents

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1. 洞房結節の一時停止、停止、および進出ブロック sinoatrial nodal pause arrest and exit block
2. 心電図チュートリアル：洞結節での調律および不整脈 ecg tutorial rhythms and arrhythmias of the sinus node
3. 先天性第3度（完全）房室ブロック congenital third degree complete atrioventricular block
4. 第2度房室ブロック：モビッツI型（ウェンケバッハブロック） second degree atrioventricular block mobitz type i wenckebach block
5. 洞不全症候群の症状および原因 manifestations and causes of the sick sinus syndrome

English Journal

Large doses of uterotonic drugs caused type II second degree sinoatrial block during cesarean section.

Quan ZF, Tian M, Chi P.
International journal of clinical pharmacology and therapeutics.Int J Clin Pharmacol Ther.2016 Jan;54(1):62-4. doi: 10.5414/CP202453.
In China, it is a routine procedure to inject 250 μg of hemabate (sterile solution, an oxytocic, contains the tromethamine salt of the (I5S)-15 methyl analogue of naturally occurring prostaglandin F2α in a solution suitable for intramuscular injection) into the myometrium of patients experiencing
PMID 26636420

Bitopic Sphingosine 1-Phosphate Receptor 3 (S1P3) Antagonist Rescue from Complete Heart Block: Pharmacological and Genetic Evidence for Direct S1P3 Regulation of Mouse Cardiac Conduction.

Sanna MG1, Vincent KP1, Repetto E1, Nguyen N1, Brown SJ1, Abgaryan L1, Riley SW1, Leaf NB1, Cahalan SM1, Kiosses WB1, Kohno Y1, Brown JH1, McCulloch AD1, Rosen H2, Gonzalez-Cabrera PJ2.
Molecular pharmacology.Mol Pharmacol.2016 Jan;89(1):176-86. doi: 10.1124/mol.115.100222. Epub 2015 Oct 22.
The molecular pharmacology of the G protein-coupled receptors for sphingosine 1-phosphate (S1P) provides important insight into established and new therapeutic targets. A new, potent bitopic S1P3 antagonist, SPM-354, with in vivo activity, has been used, together with S1P3-knockin and S1P3-knockout
PMID 26494861

Human sinoatrial node structure: 3D microanatomy of sinoatrial conduction pathways.

Csepe TA1, Zhao J2, Hansen BJ1, Li N1, Sul LV1, Lim P2, Wang Y2, Simonetti OP3, Kilic A4, Mohler PJ5, Janssen PM5, Fedorov VV6.
Progress in biophysics and molecular biology.Prog Biophys Mol Biol.2015 Dec 30. pii: S0079-6107(15)00260-6. doi: 10.1016/j.pbiomolbio.2015.12.011. [Epub ahead of print]
INTRODUCTION: Despite a century of extensive study on the human sinoatrial node (SAN), the structure-to-function features of specialized SAN conduction pathways (SACP) are still unknown and debated. We report a new method for direct analysis of the SAN microstructure in optically-mapped human hearts
PMID 26743207

Japanese Journal

洞房ブロックにおけるアセチルコリンの作用

安谷屋均
沖縄県立看護大学紀要 (15), 17-31, 2014-03
NAID 40020160095

Selective Sinoatrial Node Optical Mapping and the Mechanism of Sinus Rate Acceleration

SHINOHARA Tetsuji,PARK Hyung-Wook,JOUNG Boyoung,MARUYAMA Mitsunori,CHUA Su-Kiat,HAN Seongwook,SHEN Mark J.,CHEN Peng-Sheng,LIN Shien-Fong
Circulation journal : official journal of the Japanese Circulation Society 76(2), 309-316, 2012-01-25
… Background: Studies using isolated sinoatrial node (SAN) cells indicate that rhythmic spontaneous sarcoplasmic reticulum calcium release (Ca clock) plays an important role in SAN automaticity. … Conclusions: We conclude that, in the isolated canine RA, a high extracellular potassium concentration can suppress atrial excitability thus leading to SAN-RA conduction block, allowing selective optical mapping of the intact SAN. …
NAID 10030035379

ジアゼパム使用による静脈内鎮静法管理中に徐脈・II度の洞房ブロックが出現した症例

新崎公子,関慎太郎,山口祥子,篠原健一郎,小倉晋,山城三喜子,住友雅人,砂田勝久,中村仁也
日本歯科麻酔学会雑誌 36(5), 567-568, 2008-10-15
NAID 10024381634

Related Pictures

★リンクテーブル★

リンク元	「洞房ブロック」
関連記事	「block」「sinoatrial」

「洞房ブロック」

Sinoatrial block
	Sinus rhythm (rate = 65/min) with Type II S-A (exit) block; (see laddergram). Note that the long cycles (191) are nearly identical to twice the short cycles (190).
Classification and external resources
Specialty	cardiology
ICD-10	I45.5
ICD-9-CM	426.6
MeSH	D012848
	[edit on Wikidata]