3. CVS Development And Congenital Heart Disease

Question 1

What happens to the endocardial tubes in embryo folding?

Answer 1

A pair fuse, to create one primitive heart tube within the cardiogenic field

Question 2

Name the 6 areas of the primitive heart tube, from top to bottom

Answer 2

Aortic roots
Truncus arteriosus
Bulbus cordis
Ventricle
Atrium
Sinus venosus

Question 3

Why does cardiac looping occur?

Answer 3

The primitive heart tube elongates and runs out of room

Question 4

What areas of the primitive heart tube does the left atrium form from?

Answer 4

Small portion of primitive atrium

Absorbs proximal parts of pulmonary veins

Question 5

What areas of the primitive heart tube forms the right atrium?

Answer 5

Most of primitive atrium

Sinus venosus

Question 6

Name the 3 shunts in the foetal circulatory system

Answer 6

Ductus venosus from liver to inferior vena cava
Foramen ovale from the right atrium to left atrium
Ductus arteriosus from the pulmonary trunk to the aorta

Question 7

What does the 4th arch of the early atrial system form?

Answer 7

Right arch - proximal part of the right subclavian artery

Left arch - arch of the aorta

Question 8

What does the 6th arch of the early arterial system form?

Answer 8

Right arch - right pulmonary artery

Left arch - left pulmonary artery and ductus arteriosus

Question 9

Where does the eat recurrent laryngeal nerve become hooked around?

Answer 9

Ductus arteriosus

Question 10

What is patent ductus arteriosus (PDA)?

Answer 10

Persistent communication between the descending aorta and pulmonary artery, leading to a shunt of blood from left to right (from aorta to pulmonary artery, as high pressure to low pressure) is acyanotic

Question 11

What are the two causes of an atrial septal defect?

Answer 11

Septum primum - reabsorbed or too short

Septum secundum- too small

Question 12

What is hypoplastic left heart syndrome?

Answer 12

Left heart is underdeveloped due to inadequate right to left flow in utero. Ascending aorta small. Need shunts for survival, persistent ductus arteriosus

Question 13

What is thought to cause hypoplastic left heart syndrome?

Answer 13

Defect in development of mitral or aortic valves, leading to atresia and limited flow
Or ostmium secundum too small

Question 14

How does the septum form in the developing heart?

Answer 14

Muscular portion of septum grows upwards towards the endocardial cushions, leaving a small gap (primary interventricular formamen). Membranous part of septum fills the gap

Question 15

What causes ventricular septal defect?

Answer 15

Problem with membranous portion of interventricular septum.

Question 16

What happens in septation of the outflow tract?

Answer 16

Endocardial cushions appear in the truncus arteriosus, grow towards each other and twist around each other, forming a spiral septum.

Question 17

What does septation of the outflow tract form?

Answer 17

Aorta and pulmonary trunk

Question 18

What occurs in transposition of the great arteries (aorta and pulmonary trunk swap ventricles)?

Answer 18

Cyanosis
Is related to development of aortic and pulmonary valves
Needs shunts to be viable - bi-directional shunting

Question 19

What is tetralogy of fallot?

Answer 19

Ventricular septal defect
Over-riding aorta - right to left shunt, cyanosis
Pulmonary stenosis
Right ventricular hypertrophy

Question 20

What is dangerous about patent ductus arteriosus?

Answer 20

Left to right shunt, so increased pulmonary artery and therefore pulmonary venous pressure

Question 21

What is pulmonary atresia?

Answer 21

No opening in the right ventricle to the pulmonary trunk, requires right to left atrial shunt of venous return, and then blood to flow to lungs via persistent ductus arteriosus (left to right shunt).

Question 22

What does an atrial septal defect eventually lead to?

Answer 22

Right heart failure

Question 23

What is aortic coarctation?

Answer 23

Narrowing of the aorta, usually in area of ductus arteriosus which after birth becomes the ligamentum arteriosum