Cardio: Embryology

Question 1

Truncus arteriosus (TA), gives rise to

Answer 1

Ascending aorta Pulmonary trunk

and Aorticopulmonary Septum

Question 2

Bulbus cordis, gives rise to

Answer 2

Smooth parts (outflow tract) of Left (Aortic Vestibule)
and Right Ventricles (Conus Cordis)

Question 3

Primitive atria, gives rise to

Answer 3

Trabeculated part of Left and Right Atria

Question 4

Primitive ventricle, gives rise to

Answer 4

Trabeculated part of Left and Right Ventricles

Question 5

Primitive pulmonary vein, gives rise to

Answer 5

Smooth part of Left Atrium

Question 6

Left horn of Sinus venous (SV), gives rise to

Answer 6

Sinus Venarum (smooth part of the Right Atrium), Coronary sinus, and the Oblicque Vein of the Left Atrium

Question 7

Right horn of Sinus venous (SV), gives rise to

Answer 7

Smooth part of Right Atrium

Question 8

Right common cardinal vein and right anterior cardinal vein, gives rise to

Answer 8

Superior Vena Cava (SVC)

Question 9

Kartagener syndrome

Answer 9

• Autosomal dominant
• Primary ciliary dyskinesia (cilia moving incorrectly)
• Situs inversus

Question 10

Patent foramen ovale

Answer 10

• Failure of Septum Primum and Septum Secundum to fuse after birth
• Most are untreated
• Can lead to paradoxical emboli (venous thromboemboli that enter systemic arterial circulation
• Similar to those resulting from an ASD

Question 11

(7) Steps of Septation of the Atria

Answer 11

1. Septum Primum grows toward Endocardial Cushions, narrowing Foramen Primum
2. Foramen Secundum forms in Septum Primum (Foramen Primum disappears)
3. Septum Secundum develops as Foramen Secundum maintains right-to-left shunt
4. Septum Secundum expands and covers most of the Foramen Secundum. The residual foramen is the Foramen Ovale.
5. Remaining portion of Septum Primum forms valve of Foramen Ovale
6. Septum Secundum and Septum Primum fuse to form the Atrial Septum
7. Foramen Ovale usually closes soon after birth because of Increased Left Atrial pressure

Question 12

(3) Steps of Septation of the Ventricles

Answer 12

1. Muscular Ventricular Septum forms. Opening is called Interventricular Foramen
2. Aorticopulmonary Septum rotates and fuses with Muscular Ventricular Septum, to form the Membranous Interventricular Septum, closing Interventricular Foramen
3. Growth of Endocardial Cushions separates atria from ventricles and contributes to both atrial septation and the membranous portion of the interventricular septum

Question 13

(3) Steps of Outflow tract formation

Answer 13

1. Truncus Arteriosus rotates; Neural Crest and Endocardial Cell migrations –>
2. Truncal and bulbar ridges that spiral and fuse to form Aorticopulmonary Septum –>
3. Ascending Aorta and Pulmonary Trunk

Question 14

Dextro-Transposition of great vessels

Answer 14

• Cyanotic congential heart defect (CHD
• The Left and Right Ventricles pump in seperate circulatory cycles never oxygenating Systemic Circulatory blood with the Pulmonary system.

Question 15

Tetralogy of Fallot

Answer 15

• The AP Septum fails to align properly with the AV Septum, resulting in pulmonary stenosis (right ventricular outflow reduction)
• Overriding Aorta (dextroposition of Aorta)
• VSD and Right Ventricular Hypertrophy
• Most common cyanotic heart defect (blue baby) (R->L)
• Mixing of oxygenated and deoxygenated blood in the Left Ventricle via the Ventricular Septal Defect (VSD) and preferential flow of the mixed blood from both ventricles through the Aorta because of the obstruction to flow through the pulmonary valve

Question 16

Persistent truncus arteriosus

Answer 16

• The embryological structure known as the Truncus Arteriosus fails to properly divide into the Pulmonary Trunk and Aorta
• Results in one Arterial Trunk arising from the heart and providing mixed blood to the Coronary Arteries, Pulmonary Arteries, and Systemic Circulation

Question 17

Valve derived from endocardinal cushions of outflow tract

Answer 17

• Aortic valve
• Pulmonary valve

Question 18

Valve derived from fused endocardinal cushions
of the AV canal

Answer 18

• Mitral valve
• Tricuspid valve

Question 19

Stenotic valvular anomaly

Answer 19

Aortic stenosis occurs when abnormalities of the aortic valve lead to narrowing and obstruction between the left ventricle and the aorta.

Question 20

Regurgitant valvular anomaly

Question 21

Atretic valvular anomaly (tricuspid atresia)

Question 22

Ebstein anomaly

Answer 22

• Congenital malformation of the heart that is characterized by apical displacement of the septal and posterior tricuspid valve leaflets.
• Leading to atrialization of the right ventricle with a variable degree of malformation and displacement of the anterior leaflet.

Question 23

Fetal erythropoitesis

Answer 23

• Yolk sac (3 - 8 weeks)
• Liver (6 weeks - birth)
• Spleen (10 - 28 weeks)
• Bone marrow (18 weeks to adult)

“Young Liver Synthesizes Blood”

Question 24

Fetal Hemoglobin (HbF)

Answer 24

α₂γ₂

_{Alpha Always, Gamma Goes, Becomes Beta}

Question 25

Adult hemoglobin (HbA)

Answer 25

α2β2

Alpha Always; Gamma Goes, Becomes Beta

Question 26

HbF higher affinity for oxygen

Answer 26

• Less avid binding of 2,3-BPG
• This allows HbF to extract oxygen from (HbA) maternal hemoglobin across the placenta

Question 27

Blood entering the fetus through the umbilical vein is conducted via the ____________ into the the IVC to bypass the hepatic circulation.

Answer 27

Ductus venosus

Question 28

Most highly oxygenated blood reaching the heart via the IVC is diverted through the __________ and pumped out the aorta to the head and body.

And is also an oval opening in the Septum Secundum that provides a communication between the Atria.

Answer 28

Foramen ovale

Question 29

Deoxygenated blood entering the RA from the SVC goes:
RA –> RV –> main PA –> __________ –> descending aorta

Answer 29

Ductus arteriosus due partly to low O2 tension

Question 30

At birth, infant takes a breath:

Answer 30

• Low resistance in pulmonary vasculature causes increase left atrial pressure vs. right atrial pressure
• Foramen ovale closes (now called the fossa ovalis) Increase in O2 (from respiration) and decrease in prostaglandins (from placental separation)
• Closure of Ductus arteriosus

Question 31

Umbilical vein, gives rise to

Answer 31

Ligamentum teres hepatis (round ligament of the liver)

Question 32

Umbilical arteries, gives rise to

Answer 32

Medial umbilical ligaments

Question 33

Ductus arteriosus, gives rise to

Answer 33

Ligamentum arteriosum

Question 34

Ductus venosus, gives rise to

Answer 34

Ligamentum venosum

Question 35

Foramen ovale, gives rise to

Answer 35

Fossa ovalis

Question 36

Allantois, gives rise to

Answer 36

• Urachus-median umbilical ligament
• The urachus is the part of the allantoic duct between the bladder and the umbilicus.
• Urachal cyst or sinus is a remnant

Question 37

Notochord, gives rise to

Answer 37

Nucleus pulpous of intervertebral disc

Question 38

Levo-Transposition of the great vessels

Answer 38

• acyanotic heart defect
• The primary arteries are transposed, with the aorta anterior and to the left of the pulmonary artery, and the morphological left and right ventricles are also transposed

Question 39

Divides the Truncus Arteriosus into the Aorta and Pulmonary trunk

Answer 39

AP Septum

Question 40

Aortic Arch #1

Answer 40

Has no derivative because it disappears soon after development.

Question 41

Aortic Arch #2

Answer 41

Has no derivative because it persists only during the early development.

Question 42

Aortic Arch #3

Answer 42

Forms the Common Carotid Arteries and the proximal part of the Internal Carotid Arteries

Question 43

Aortic Arch #4

Answer 43

Forms the Aortic Arch on the Left and the

• *Brachiocephalic Artery** and the
• *Proximal Subclavian Artery** on the Right.

Question 44

Aortic Arch #5

Answer 44

Has no derivative.

Question 45

Aortic Arch #6

Answer 45

Forms the Proximal Pulmonary Arteries
and Ductus Arteriosus.