embrology and anatomy of cardiovascular system
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Cardiovascular SystemEmbryology and Anatomy*
Dr. Kalpana MallaMBBS MD (Pediatrics)
Manipal Teaching Hospital
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Embryonic Heart Development
The heart develops in the embryo during post-conception weeks 3 - 8
Beginning Development
• Early week post-conception: 2 endothelial tubes• Mid-week : endothelial tubes fuse to form a
tubular structure• 28 days following conception: the single-
chambered heart begins to pump blood
Week 4
• Heart has: – single outflow tract, the truncus arteriosus (divides to
form aorta & pulmonary veins)– Single inflow tract, the sinus venosus (divides to form
the superior and inferior vena cavae)– Single atrium– Single ventricle– AV canal begins to close
Weeks 5
Week 5
• AV canal closure complete
• Formation of atrial and ventricular septums
• Heart grow rapidly, and fold back on itself to form its completed anatomic shape
Week 7
• Ventricular septum fully developed
• Coronary Sinus forms
• Outflow tracts (aorta & pulmonary truck) fully separated
8 Weeks After Conception
• By the end of the 8th week after conception the fetus has a fully developed 4-chambered heart
Layers of Heart
• Pericardium (most superficial)
– Visceral, parietal
• Myocardium (middle layer)– Cardiac muscle
• Endocardium (inner)– Endothelium
Lines the heart
Creates the valves
Right Heart Chambers
• Right Atrium (most of base of heart)– IVC, SVC, Coronary sinus – Rt atrium– Ventral wall = rough Pectinate muscle– Fossa Ovalis- on interatrial septum, remnant
of Foramen Ovale
Right Heart Chambers
• Right Ventricle– RA – TV – RV – Pulmonary Valve- pulmonary trunk
- lungs– Trabeculae Carnae – muscle ridges along ventral
surface– Papillary Muscle-cone-shaped muscle to which
chordae tendinae are anchored– Moderator Band-muscular band connecting anterior
papillary muscle to interventricular septum
Left Heart Chambers
• Left Atrium– Lungs - 4 Pulmonary Veins –LA– Pectinate Muscles line only auricle
Left Heart Chambers
• Left Ventricle (apex of heart)– LA – mitral valve – LV – AV – aorta – body– Same structures as Rt Ventricle: Trabeculae
carnae, Papillary muscles, Chordae tendinae– No Moderator Band
Heart Valves - heart sounds
Heart Valves: Lub*-Dub
• Tricuspid Valve: Right AV valve – 3 Cusps (flaps) - anchored in Rt. Ventricle by
Chordae Tendinae– Chordae Tendinae prevent inversion of cusps
into atrium– Closure of AV valve – 1st heart sound
Heart Valves: Lub*-Dub
• Bicuspid (Mitral) Valve: Left AV valve– 2 cusps anchored in Left Ventricle by chordae
tendinae– Functions same as Rt. AV valve
Heart Valves: Lub*-Dub
• **Semilunar valves:
• Pulmonary Semilunar Valve: RV to Pulmonary Trunk– Aortic Semilunar Valve: LV to Aorta– 3 cusps– Closure of SV – 2nd heart sound
The Great Vessels and major branches
Aorta (from Left Ventricle)
• Ascending– Coronary arteries
• Aortic Arch – Brachiocephalic trunk– Left Common Carotid– Left Subclavian
• Descending (Thoracic/Abdominal)– Many small branches to organs
The Great Vessels
• Pulmonary veins
- 4 into heart (lt atrium) • Pulmonary Trunk (from Rt Ventricle)
- -2 Pulmonary Arteries into lungs
– Inferior/Superior Vena Cava / Coronary sinus
Flow of Blood• Deoxygenated - SVC+IVC, Coronary Sinus -
enters RA - Tricuspid Valve - RV - Pulmonary Valve - Pulmonary trunk → Pulmonary Arteries → lungs
• Oxygenated blood - 4 P Veins - LA - Bicuspid/Mitral Valve – LV – Aortic Valve - Aorta - body
The Normal Heart
Circulation
• Coronary circulation – the circulation of blood within the heart
• Pulmonary circulation – the flow of blood between the heart and lungs
• Systemic circulation – the flow of blood between the heart and the cells of the body
Fetal Circulation: main differences
1. Presence of placental circulation
2. Presence of ductus venosus – UV to IVC
3. Absence of gas exchange in collapsed lungs
4. Widely open foramen ovale
5. Widely open ductus arteriosus
Three Shunts of Fetal Circulation
• Ductus Venosus (Ligamentum venosum)
- Oxygenated blood from placenta - fetal UV - IVC – RA - by passes liver
• Foramen Ovale
- From RA to LA – by passes the RV,Pulmonary trunk -no blood to lungs
• Ductus Arteriosus– Blood from pulmonary trunk to aortic arch – by passing lungs
Fetal Circulation
• Umbilical Vessels:
-2 Umbilical Arteries (Medial Umbilical Ligaments) =deoxygenated blood from fetus to placenta– 1 Umbilical Vein (Ligamentum teres)= Oxygenated
blood to fetus from placenta
Fetal Circulation
– Placenta - umbilical vein - ductus venosus –IVC – RA- foramen ovale –LA –LV – Aorta – systemic circulation
– RA – RV – pulmonary trunk - ductus arteriosus – aortic arch - enter the systemic circulation, by passing the pulmonary circulation
Fetal circulation before birth
• Note :oxygenated blood mixes with deoxygenated blood in
(I)Liver
(II)IVC
(III)rt. Atrium
(IV)Lt. Atrium
(V)entrance of the ductus arteriosus into the descending aorta
After Birth
• Lungs expands with air and pulmonary vascular resistance falls. Pulmonary blood flow increases
• The foramen ovale and ductus venosus close during the first day of life
• The ductus arteriosus close during the first 24 – 72 hours of life
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Medical Post [ www.themedicalpost.net ]
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