Embryology

Question 1

Describe the embryological septation of the Atrial chambers

Answer 1

1. septum primum grows toward endocardial cushions, narrowing the foramen primum
2. the foramen secundum forms in septum primum
3. the septum secundum develops as foramen secundum maintains right to left shunt
4. the septum secundum expands and covers most of the foramen secundum. The residual foramen is the foramen ovale
5. the 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 2

the primitive ventricle gives rise to what structures

Answer 2

the trabeculated part of the left and right ventricles

Question 3

How are the ascending aorta and the pulmonary trunk formed?

Answer 3

from neural crest and endocardial cell migrations forming truncal and bulbar ridges that spiral and fuse to form aorticopulmonary septum

Question 4

the right common cardinal vein and right anterior cardinal vein give rise to what structure?

Answer 4

the superior vena cava

Question 5

what is an ebstein anomaly?

Answer 5

displaced valve

Question 6

The primitive atrium gives rise to what structure?

Answer 6

the trabeculated part of the left and right atria

Question 7

The bulbus cordis gives rise to what structure?

Answer 7

the smooth parts of the right and left ventricles

Question 8

the right horn of sinus venosus gives rise to what structure?

Answer 8

the smooth part of the right atrium (sinus venarum)

Question 9

what can occur due to conotruncal abnormalities resulting from failure of neural crest cells to migrate?

Answer 9

can result in

• transposition of great vessels
• tetralogy of fallot

and persistent truncus arteriosus

Question 10

what structres are derived from the fused endocardial cushions of the AV canal?

Answer 10

the mitral/tricuspid valves

Question 11

the left horn of sinus venosus gives rise to what structure?

Answer 11

the coronary sinus

Question 12

The endocardial cushion gives rise to what structures?

Answer 12

The atrial septum, membranous interventricular septum, AV and semilunar valves

Question 13

What causes a patent foramen ovale

Answer 13

the failure of septum primum and septum secundum to fuse after birth. Most are left untreated

Question 14

what is the effect of Indomethacin?

Answer 14

Indomethacin helps close the patent ductus arteriosus- becomes ligamentum arteriosum

Question 15

How does the primary heart establish left-right polarity? At What week?

Answer 15

the primary heart tube loops to establish left-right polarity and this begins at week 4 of gestation

Question 16

A patent foramen ovale is a risk factor for what condition?

Answer 16

can lead to paradoxical emboli (venous thromboemboli that enters systemic arterial circulation)

Question 17

what changes occur in the heart once an infant takes their first breath?

Answer 17

1. first breath
2. decreased resistance in pulmonary vasculature
3. increased left atrial pressure vs, right atrial pressure
4. change in pressure results in closing of the foramen ovale (becomes fossa ovalis)
5. increased in O2 from respiration, and decrease in prostaglandins from placental separation
6. closure of ductus arteriosus
   7.

Question 18

the primitive pulmonary vein gives rise to what structure?

Answer 18

the smooth part of the left atrium

Question 19

the ligamentum teres hepatis (round ligament) is a remnant of what embryological structure?

Answer 19

it is a remnant of the umbilical vein

Question 20

Describe the embryological development of the ventricles

Answer 20

1. muscular interventricular septum forms opening is called the interventricular foramen
2. the aorticpulmonary septum rotates and fuses with muscular ventricular septum, closing the interventricular foramen
3. growth of endocardial cushions separates atria from ventricles and contributes to both atrial septation and membranous portion of the interventricular septum
   4.

Question 21

What is the most common congenital cardiac anomoly? Where does it usually occur?

Answer 21

Ventricular septal defect

• usually occurs in the membranous septum

Question 22

what structures are derived from the endocardial cushions of outflow tract?

Answer 22

the aortic and pulmonary valves

Question 23

What week of embryological development does the heart beat spontaneously?

Answer 23

by week 4

Question 24

Prostaglandins E1 and E2 have what effect?

Answer 24

the k’EE’p the ductus ateriosus open

Question 25

Describe the 3 important shunts in fetal circulation

Answer 25

1. blood enters fetus through the umbilical vein and is conducted via the ductus venosus into the IVC, bypassing the hepatic circulation
2. most of the oxygenated blood reaching the heart via the IVC is directed through the foramen ovale and pumped into the aorta to supply the head and body
3. deoxygenated blood from the SVC passes through the Right atrium- right ventricle- main pulmonary artery - ductus arteriosus- descending aorta (due to high pulmonary artery resistance)

Question 26

The Truncus Arteriosus gives rise to what structure?

Answer 26

The ascending Aorta and pulmonary trunk