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The Cardiovascular System (Part I)
黃敏銓
解剖學暨細胞生物學研究所
Congenital heart defects(CHDs)
台灣兒童心臟學會
Sinus venarum
Membranous
septum
Conus arteriosus
(infundibulum)
Aortic vestibule
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The Cardiovascular System
1. The first major system to function
2. The primordial heart and vascular
system appear in the middle of the third
week
3. The heart starts to function (beat) at the
beginning of the fourth week
5
The cardiovascular system is
derived mainly from:
• Mesoderm
– First / Primary heart field (FHF)
– Second / Secondary heart field (SHF): from
pharyngeal mesoderm
• Neural crest cells
J Cardiovasc Dev Dis. 2015 Dec; 2(4): 248–272.
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Angioblastic cord
Heart primordium
Angioblastic cord18 days
Early development of the heart
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Fusion of endocardial heart tubes
Ventral views
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Primordial myocardium (from splanchnic mesoderm)
Cardiac jelly
Pericardial coelom
22-day
20-day
Fusion of endocardial heart tubes
Dorsal mesocardium
Epicardium
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Truncus arteriosus
Bulbus cordis
Primordial ventricle
Primordial atrium
Sinus venosus
U-shaped bulboventricular loop
24 days
有不同命名方式
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Circulation through primordial heart
1
2
3
4
5
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Sinus venosus
End of 4th week: unidirectional flow
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Partitioning of primordial heart
• begins around middle of the 4th week.
• is completed by the end of the 8th week.
• includes partitioning of:
– Atrioventricular canal
– Primordial atrium
– Primordial ventricle
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Partitioning of Atrioventricular Canal
Endocardial cushions
(from cardiac jelly)
End of 4th week
5th week
Fused endocardial cushions
Left AV canal
Transformed endocardial cushions also contribute to the formation of valves and membranous septa of the heart.
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AV endocardial cushions
the primordia of the valves and membranous septa
Bone morphogenetic protein (BMP2)
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Partitioning of primordial atrium
• begins at the end of the 4th week.
• is divided into right and left atria by:
– Septum primum
– Septum secundum
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Septum primum
Septum primum
Endocardial cushion
Foramen primum(Ostium primum)
Foramen secundum(Ostium secundum)
Septum secundum
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Septum primum
Foramen primum
Septum primum
Foramen primum
Foramen secundum
Foramen primum
Foramen secundum
Septum primum
Septum secundum
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Septum secundumSeptum secundum (upper limb)
Valve of oval foramen(from septum primum)
Oval foramen
Foramen secundum
Oval foramen
Valve (from septum primum)
5th~6th week
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Valve of oval foramen
Septum primum
Valve of oval foramen
Oval foramen(open)
Septum secundum
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Before birth After birth
Oval foramenOval fossa
Septum primum(valve of oval foramen)
Septum secundum
Oval fossa is a remnant of oval foramen
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Development of sinus venosus
Left horn of sinus venosus Right horn of sinus venosus
Opening of sinus venosus into primordial atrium
Dorsal view (4th week)
RightLeft
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Progressive enlargement of the right horn results from two left-to-right shunts of blood
Dorsal view (7 weeks)RightLeft
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Right horn of sinus venosus
Left horn of sinus venosus
Sinus venarum of right atrium
Coronary sinus
Primordial atrium
Doral view
26 days
8 weeks
RightLeft
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Right sinuatrial valve →• Crista terminalis• Valve of IVC• Valve of coronary sinus
Crista terminalis
Valve of inferior vena cava
Valve of coronary sinus
Left sinuatrial valve →fused with septum secundum →Interatrial septum
Right Left
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Absorption of the pulmonary vein into the left atrium
6 weeks5 weeks
8 weeks
Smooth-walled part of left atrium
Left auricle
Primordial left atrium
Primordial pulmonary vein
Right Left
Cardiovasc Res (2002) 54 (2): 287-294.
The role of pulmonary veins in atrial fibrillation
(Pharmacol Ther. 2009 Nov;124(2):207-18.)
http://www.doctortipster.com/
myocardial sleeves of pulmonary veins
心房顫動(atrial fibrillation)Pulmonary vein ablation
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Partitioning of primordial ventricle
Interventricular septum(muscular part)
Interventricular foramen
Fused endocardial cushions
5th week
Expansion
Right Left
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Bulbus cordis incorporates into the walls of ventricles
Conus arteriosus(infundibulum)
Aortic vestibule
5 weeks 6 weeks
Aortic vestibule
Membranous septum
Membranous part of IV septum
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Closure of the interventricular foramen
Right bulbar ridge
Fused
endocardial
cushions
Membranous part of IV septum
7 weeks
Left bulbar ridge
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Cavitation of the ventricular walls forms a sponge-work of muscular bundles – trabeculae carneae
Trabeculae carneae
Chordae tendinae
Papillary muscle
5 weeks 6 weeks
7 weeks
20 weeks
Right Left
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Partitioning of Bulbus Cordis and Truncus Arteriosus
Truncal ridge
Bulbar ridge
Truncus arteriosus
Bulbus cordis
Pulmonary trunk
Aorta
Aorticopulmonary septum
5 weeks
6 weeks
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Spiral form of Aorticopulmonary Septum
Development of cardiac valves (semilunar valves)
Dorsal valve swelling
Ventral valve swellingBulbar ridges
Swellings of subendocardial tissue
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Valve swelling
Hollowing and thinning of valve swellings
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Cardiac conduction system
Sinuatrial (SA) node (5th week)
Atrioventricular (AV) node
Atrioventricular bundle
Branches of AV bundleRight Left
Sinus venosus
Fetal circulation
Ductus venosus
Ductus arteriosus
Foramen ovale
Sphincter
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Transitional Neonatal Circulation
1. Alteration of the lungs
• Fall in pulmonary vascular resistance
• Increase pulmonary blood flow
• Thinning of walls of pulmonary arteries
2. The oval foramen closes.
• Higher left atrium pressure
• Thicker left ventricular wall by the end of 1st month
3. The ductus arteriosus constricts.
• Close: Oxygen, bradykinin, indomethacin (PGE2 inhibitor)
• Open: Hypoxia, PGE2, prostacyclin (PGI2)
4. The umbilical arteries constrict.37
Ligamentum teres(umbilical vein)
Ligamentum venosum(ductus venosus)
Ligamentum arteriosum(Ductus arteriosus)
Oval fossa(Foramen ovale)
Medial umbilical ligament(umbilical artery, distal)
Superior vesical artery (umbilical artery, proximal)
Adult Derivatives of fetal vascular structures
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