CONDUCTION SYSTEM ANATOMY

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CONDUCTION SYSTEM ANATOMY

• Haitham Taani

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Conduction system

• SA node
• internodal pathways
• atrioventricular Node
• atrioventricular bundle
• Lt bundle branch
• Rt bundle branch
• purkinje fibers
• ventricular myocardial fibers

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SA node

• 15x5x1.5 mm
• on the lateral surface of SVC and RA near the
  crista terminalis
• lies superficially at the anteriolateral aspect
  of junction between SVC and RA appandage
• In rare cases medially along the ridge of
  atriocaval junction

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SA node.. Arterial supply

• Branch of RCA in 55
• branch of Cx in 45
• When arise from the RCA it courses posteriorly
  and superiorly over the anterior wall of RA
  beneath the RA appandage to the base of SVC
• the it encircle the SVC either
  clockwise,counterclockwise or bifurcates

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SA node .arterial supply

• when arises from Cx it courses over the LA
  appandage

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Internodal pathways

• the ends of SA node fibers fuse with surrounding
  atrial muscle fibers
• The A.P originating in SA node travels through
  the entire atrial mass to reach the AV node
• classically divided into
• ant. and medial ant and post. To F.O
• post. Pathwaycaudal to F.O

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AV node

• On the Rt. Atrial side of central fibrous body
  (Rt. Trigone) in the muscular portion of
  atrioventricular septum,
• just anteriosuperior to ostium of C.S
• Avarage dimentions in adult1x3x6 mm
• The Lt. surface lies against mitral annulus
• it is flat and oval in shape

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AV node

• within the koch triangle which formed by
• septal leaflt of TV
• Tendon of Todaro
• coronary sinus

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Bundle of HIS

• Direct continuation of AV node
• passes through the Rt. Trigone of central
  fibrous body to reach the posterioinferior
  surface of membranous septum
• membranous septum localized from the atrial
  side by identifying the commissure of septal and
  ant. Leaflet of TV (just inferior)

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Bundle of HIS..

• Lies on the Lt side 75-80
• Rt. Side 20-25
• Branching occurs neneathe the commissure
  between Rt. And NC cusp of AO.V

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• AV node directly in front of ostium of C.S
• Line between C.S and commissure of ant.and
  septal leaflet of TV Area of AV node HIS bundle
• membranous septumjust inf. To that commissure

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• relation to AO.V
• AV node in atrioventricular septum on the
  Rt. Atrial side of trigone post to
  noncoronary cusp
• HIS BUNDLE branching occur beneath the
  commissure of Rt. And N.C cusp

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LEFT BUNDLE BRANCH

• connected to HIS bundle by narrow stem
• subdivided to 2 or 3 main radiation
• anterior towards the ant.lat. Pappilary
  muscle of LV
• Posterior towards theposteriomedial
  pappilary muscle (wider)

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Right bundle branch

• originated from HIS in the region of ant. Inf.
  Margin of membranous septum
• Then along the moderator band passing toward
  the base of anterior pappilary muscle

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