Hy Embryology 06 Part 2

Front 1

Describe formation of the atrioventricular septum

Back 1

1. The dorsal AV cusion and the ventral AV cushion approach each other and fuse to form the AV septum
2. The AV septum partitions the AV canal into the right AV canal and the left AV canal

Front 2

Describe persistent common AV canal

Back 2

1. Caused by failure of fusion of the dorsal and vental AV cushions
2. Results in a condition in which the common AV canal is never partitioned into the right and left AV canals, so that a large hole can be found in hte center of the heart
3. The tricuspid and bicuspid valves are represented by one valve common to both sides of the heart
4. Two common hemodynamic abnormalities are found
a. L->R shunting of blood from the LA to the RA, causing an enlarged RA and RV
b. Mitral valve regurgitation, causing an enlarged LA and LV

Front 3

Describe Ebstein's anomaly

Back 3

1. Caused by the failure of the posterior and septal leaflets of the tricuspid valve to attach normally to the annulus fibrosus
2. Instead they are displaced inferiorly into the RV
3. Rsults in a condition in which the RV is divided into a large, upper, "artialized" portion and a smaller, lower, functional portion
4. Due to the small, functional portion of the RV, there is reduced amount of blood available to the pulmonary trunk
5. It is usually assocaited with an ASD
6. AP radiograph shows massive cardimegaly due to enlargement of the RA

Front 4

Describe Foramen primum defects

Back 4

1. Caused by a failure of the AV septum to fuse with septum primum
2. Results in a condiution in which the foramen primum is never closed and is generally accompanied by an abnormal mitral valve

Front 5

Describe Tricuspid atresia (hypoplastic right heart)

Back 5

1. Caused by an insufficient amount of AV cushion tissue available for the rormation of the tricuspid valve
2. Results in a condition in which there is complete agenesis of the tricuspid valve so that no communication between the RA and RV exists
3. Associated clinincal with marked cyanosis and is always accompanied by the following:
a. Patent foramen ovale
b. Interventicular septum defect
c. Overdeveloped LV
d. Underdeveloped RV
4. AP radiograph shows a normal-sized heart with a convex left cardiac contour

Front 6

Describe formation of the interventricular septum

Back 6

1. The muscular IV septum develops in the midline on the floor of the primitive ventricle and grows toward the fused AV cushions
2. IV formation is located between the free edge of the muscular IV septum, which forms by the proliferation and fusion of tissue from three sources:
a. Right bulbar ridge
b. Left bulbar ridge
c. AV cushions

Front 7

Describe membranous VSD

Back 7

1. Caused by faulty fusion of the right bulbar ridge, left bulbar ridge, and AV cushions
2. Results in a condition in which an opening between the RV and LV allows free flow of blood
3. A large VSD is initially associated with L->R shunting of blood, increased pulmonary blood flow, and pulmonary hypertension
4. Patients iwth L->R shunting of blood complain of excessive fatigue on exertion
5. AP radiograph demonstrates cardiomegaly and a marked enlargment of the main pulmonary artery

Front 8

Describe Eisenmenger Syndrome

Back 8

1. Uncorrected VSD, ASD, or PDA
2. Initially, a VSD, ASD, or PDA is associated with L->R shunting of blood, increased pulmonary blood flow, and pulmonary hypertension
3. Later, the pulmonary hypertension causes marked proliferation of the tunica intima and tunica media of pulmonary muscular arteries and arterioles, resuting in a narrowing of their lumen
4. Ultimately, pulmonary resistance may become higher than systemic resistance and cause R->L shunting of blood and cyanosis

Front 9

Describe Muscular VSD

Back 9

Caused by single of multiple perforations in the muscular IV septum

Front 10

Describe Common venticle (cor triloculare biatriatum)

Back 10

Caused by failure of the membranous or muscular IV septa to form

Front 11

Describe the formation of the arterial system

Back 11

1. In the head and neck region, the arterial pattern develops mainly from six pairs of arteries (called aortic arches) that course through the pharyngeal arches
2. The aortic arch arteries undergo a complex remodeling process that results in the adult arterial pattern
3. In the rest of the body, the arterial patterns develop mainly fromt he right and left dorsal aortae
4. The right and left dorsal aortae fuse to form the dorsal aorta, which the sprouts posterolateral arteries, lateral arteries, and ventral arteries (vitelline and umbilical)

Front 12

Describe the formation of the arterial system in the head and neck

Back 12

1. In the head and neck region, the arterial pattern develops mainly from six pairs of arteries (called aortic arches) that course through the pharyngeal arches
2. The aortic arch arteries undergo a complex remodeling process that results in the adult arterial pattern

Front 13

Describe postductal coarctation of the aorta

Back 13

1. Occurs when the aorta is abnormally constricted
2. A postductal coarctation is found distal to the orign of the left subclavian artery and inferior to the ductus arteriosus
3. Clinically associated with increased BP in hte upper extemities, lack of pulse in femoral artery, high risk of both cerebral hemorrhage, and bacterial endocarditisi
4. Collateral circualation around the constriction involves the internal thoracic, intercostal, superior epigastic, inferior epigastric, and external iliac arteries
5. Dilation of the intercostal arteries caused by erosion of the lower border of the ribs (called "rib notching"), which can be seen on X-ray
6. Less commonly, a preductal coarctation may occur where the constriction is located superior to the ductus arteriosus
7. Turner syndrome (45,XO) is associated with a preductal coarctation

Front 14

Describe patent ductus arteriosus

Back 14

1. Occurs when the ductus arteriosus- a connection between the L pulmonary artery and aorta- fails to close
2. Normally the ductus arteriosus functionally closes within a few hours after birth via smooth muscle contraction to ultimately form the ligamentum arteriosum
3. A PDA causes L->R shunting of oxygen rich blood from the aorta back into the pulmonary circulation
4. A PDA can be treated with prostaglanding-sunthesis inhibitors (such as indomethacin), acethylcholine, histamine, and catecholamins, all of which promote closure of the ductus arteriosus
5. PGE1, intauterine asphysia, and neonatal asphyxia sustain patency of the ductus arteriosus
6. A PDA is very common in premature infants and maternal rubella infection

Front 15

Describe the devlopment of the venous system

Back 15

1. Develops from the vitelline, umbilical, and cardinal veins that empty into the sinus venosus
2. These veins undergo remodeling due to a redirection of venous blood from the L side of the body to the R side in order to empty into the RA

Front 16

What adult arterial and venous structures develop from aortic arch 1?

Back 16

Portion of Maxillary Artery

Front 17

What adult arterial and venous structures develop from aortic arch 2?

Back 17

Portion of Stapedial Artery

Front 18

What adult arterial and venous structures develop from aortic arch 3?

Back 18

-Portion of Right and Left common carotid arteries
-Right and Left internal carotid arteries

Front 19

What adult arterial and venous structures develop from aortic arch 4?

Back 19

-Portion of Right subclavian artery
-Portion of arch of the aorta

Front 20

What adult arterial and venous structures develop from aortic arch 5?

Back 20

Regresses in human

Front 21

What adult arterial and venous structures develop from aortic arch 6?

Back 21

-Portion of Right and Left pulmonary arteries
-Ductus arteriosus

Front 22

What adult arterial and venous structures develop from posterolateral branches of the dorsal aorta?

Back 22

-Arteries to upper and lower extremities
-Intercostal, lumbar, and lateral sacral arteries

Front 23

What adult arterial and venous structures develop from lateral branches of the dorsal aorta?

Back 23

Renal, suprarenal, and gonadal arteries

Front 24

What adult arterial and venous structures develop from the vitelline arteries from the ventral branches of the dorsal aorta?

Back 24

Celiac, superior mesenteric, and inferior mesenteric arteries

Front 25

What adult arterial and venous structures develop from the umbilical arteries from the ventral branches of the dorsal aorta?

Back 25

-Portion of internal iliac arteries, superior vesical arteries
-Medial umbilical ligaments

Front 26

What adult arterial and venous structures develop from the right and left vitelline veins

Back 26

Portion of the IVC, hepatic veins and sinusoids, ductus venosus, portal vein, inferior mesenteric vein, superior mesenteric vein, splenic vein

Front 27

What adult arterial and venous structures develop from the right umbilical vein

Back 27

Hepatic sinusoids (degenerates early in fetal life)

Front 28

What adult arterial and venous structures develop from the left umbilical vein?

Back 28

Hepatic sinusoids, ligamentum teres

Front 29

What adult arterial and venous structures develop from the anterior cardial veins?

Back 29

SVC, internal jugular veins

Front 30

What adult arterial and venous structures develop from the posterior cardinal veins?

Back 30

Portion of IVC, common iliac veins

Front 31

What adult arterial and venous structures develop from the subcardinal veins?

Back 31

Portion of IVC, renal veins, gonadal veins

Front 32

What adult arterial and venous structures develop from the supracardinal veins?

Back 32

Portion of IVC, intercostal veins, hemiazygous vein, azygous vein