Development Of The Cardiovascular System

Front 1

When is the primitive vertebrate cardiovascular plan present by?

Back 1

Week 4

Front 2

Where does the first wave of hematopoiesis occur?

Back 2

Extra-embryonic yolk sac

Leads to production of primitive embryonic nucleated red blood cells in blood islands

Front 3

What are the 3 phases of embryonic hematopoiesis?

Back 3

1. Primordial - yolk sac followed by aorta-gonad-mesonephros
2. Hepatosplenothymic - weeks 4-8
3. Medullolymphatic - week 9--> (by 5th month in utero bone marrow has become major site of hematopoiesis)

Front 4

Which gene is essential for blood formation?

Back 4

Runx1

Front 5

What are the two ways in which blood vessels are formed?

Back 5

1. Vasculogenesis - blood vessels arise from coalescence of hemangioblasts, which arise from blood islands
2. Angiogenesis - vessel formation via branches arising from existing vessels

Major vessels form via vasculogenesis

Front 6

What are the steps in vasculogenesis?

Back 6

FGF binds to mesenchymal cells-->hemangioblasts
VEGF elicits regional change in blood islands
Central cells become hematopoietic stem cells
Peripheral cells differentiate into angioblasts--> endothelium of blood vessels

Front 7

How does vascular development occur?

Back 7

Once the vascular bed (primary capillary plexus) is established, VEGF then regulates formation of additional vasculature via angiogensis

Front 8

What is the embryonic vascular circuit?

Back 8

Series of aortic arches that connect to dorsal aorta
Blood drained by anterior and posterior cardinal veins

Front 9

What are the extraembryonic vascular circuits?

Back 9

Vitelline - supply and drain yolk sac

Umbilical (placental) - umbilical vein carries oxygenated blood from placenta

Front 10

What is the adult structure that corresponds with the Truncus Arteriosus?

Back 10

Aorta
Pulmonary Trunk

Front 11

What is the adult structure that corresponds with the Bulbus Cordis?

Back 11

Smooth part of right ventricle (conus cordis)
Smooth part of left ventricle (aortic vestibule)

Front 12

What is the adult structure that corresponds with the primitive ventricle?

Back 12

Trabeculated part of right and left ventricles

Front 13

What is the adult structure that corresponds with the primitive atrium?

Back 13

Trabeculated part of right and left atria (auricles)

Front 14

What is the adult structure that corresponds with the sinus venosus?

Back 14

Smooth part of right atrium (sinus venarum)
Coronary sinus
Oblique vein of left atrium

Front 15

How does the heart go from a tube to its recognized form?

Back 15

Cardiac looping
The heart bends on itself, forming a bulboventricular loop

Front 16

What is dextrocardia?

Back 16

Heart bends to the left instead of the right
Heart displaced to the right with transposition of heart and great vessels
Most common positional abnormality

Front 17

What are endocardial cushions?

Back 17

Dorsal and ventral blocks of tissue grow together

Their formation and fusion is the critical first step in the development of the 4-chambered heart

Front 18

What is common AV canal?

Back 18

Defect in endocardial cushions
Enlarged pulmonary trunk
Less resistance in the pulmonary circulation than in the systemic circulation

Front 19

How is the interventricular septum formed?

Back 19

Muscular portion develops in the midline on the floor of the primitive ventricle
Grows upward towards endocaardial cushions and down growing bulbar ridges

Front 20

What are ventricular septal defects?

Back 20

Opening between L & R ventricles, associated shunting of blood
4 types based on position and severity
25% of all congenital heart defects
Most occur in muscular portion (these spontaneously close)

Front 21

How is the atrial septum formed?

Back 21

Septum primum forms almost to ECC, but before it fuses it forms foramen secundum
Septum primum then fuses with ECC (closes foramen primum)
Septum secundum forms, creating valve of forman ovale

Front 22

What are atrial septal defects?

Back 22

Common atrium
Ostium (foramen) primum defects - similar to ECC defects
Secundum type - involve foramen ovale and septum primum
Sinus Venosus - usually near opening of SVC
Fairly common, present in 10-15% of patients with congenital cardiac anomalies

Front 23

What occurs in the changes of the sinus venosus?

Back 23

Right horn enlarges as blood is shunted from L-->R
Move all systemic inflow to the right side

Front 24

Describe the shunt for the vitelline veins.

Back 24

Veins become incorporated into liver as hepatic sinusoids, hepatic veins, part of IVC and some of the veins that drain the GI tract

Front 25

Describe the shunt for the umbilical vein.

Back 25

Loses direct connection with heart (ligamentum teres hepatis)
Joins large venous shunt - ductus venosus

Front 26

What is the ductus venosus?

Back 26

Connects umbilical vein with IVC
Bypasses the liver and diverts oxygenated blood into the heart

Front 27

What is the shunt involving the cardinal veins?

Back 27

Anterior cardinal veins become connected
Anastomosis becomes left brachiocephalic vein
Right anterior cardinal and common cardinal become SVC

Front 28

What does the crista terminalis mark the division between?

Back 28

Embryonic sins venosus and embryonic primitive atrium (auricles)

Front 29

Describe the partitioning of the great vessels.

Back 29

Tissue forming aorticopulmonary septum twists inside the truncus arteriosus so that pulmonary trunk connects with right ventricle and aorta connects with left ventricle
More complex = increased possibility of errors

Front 30

What is Eisenmenger's Syndrome?

Back 30

Equal division of truncus, incomplete fusions of bulbar ridges inferiorly --> VSD
Initial L-->R shunt, increased pulmonary blood flow and hypertension
Proliferation in intima and media to narrow lumen
Increased pulmonary resistance causes R-->L shunt and cyanosis

Front 31

What is Tetrology of Fallot?

Back 31

Pulmonary stenosis
VSD
Overriding aorta
Rt. ventricular hypertrophy

Front 32

How many pairs of aortic arches are there?

Back 32

6 pairs

Connect aortic sac/TA to dorsal aortae

Front 33

Which derivations of the aortic arches form the aorta and the ductus arteriosus?

Back 33

IV - aorta
VI - ductus arteriosus, also the pulmonary arteries

Front 34

How are pulmonary veins formed?

Back 34

Form independently, are not remade
Venous drainage channels from lungs converge to form single vessel-->left atrium
As atrium expands, tissue of the vein is incorporated into the wall

Front 35

What is Total Anomalous Pulmonary Venous Return (TAPVR)?

Back 35

Rare congenital malformation in which all four pulmonary veins do not connect normally to the left atrium
Instead, all four pulmonary veins drain abnormally to the right atrium by way of an abnormal (anomalous) connection

Front 36

What are the types of TAPVR?

Back 36

Supracardiac - pulmonary veins drain to rt. atrium via SVC
Cardiac - pulmonary veins come together behind heart and then drain to rt. atrium through coronary sinus
Infracardiac - pulmonary veins drain to the rt. atrium through the liver (hepatic) veins and the IVC

Front 37

T/F: All types of TAPVR must have an ASD.

Back 37

True

Because none of the pulmonary veins connect normally to the left side of the heart, blood must be shunted from rt. atrium across the ASD

Front 38

What is right aortic arch?

Back 38

Persistence of right 4th arch distal to the right subclavian
Left segment caudal to left subclavian disappears
Isolated
Situs inversus complex

Front 39

What is double aortic arch?

Back 39

Segment of right 4th aortic arch caudal to the right subclavian persists
Vascular ring around trachea and esophagus

Front 40

What is coarctation of the aorta?

Back 40

Coarctation of the aorta distal to the left subclavian
Typically near the ductus arteriosus: postductal (adult) or preductal (infantile)
Collateral circulation often includes the ITA and branches

Front 41

What is ectopia cordis?

Back 41

Heart forms outside the body