Cardiac embryology

Question 1

What is the pathology in which a single vessel arises from the heart instead of a separate aorta and pulmonary trunk?

Answer 1

Common truncus arteriosus

Question 2

Which embryological defect occurs in a common / persistent truncus arteriosus?

Answer 2

Failure of bulbar/ truncal ridge formation

Question 3

Which 4 defects are present in the tetralogy of Fallot?

Answer 3

Pulmonary stenosis

Ventricular septal defect (VSD)

Overriding aorta

Right ventricular hypertrophy

Question 4

What is transposition of the great vessels?

Answer 4

The aorta and pulmonary trunk are switched, so the aorta arises from the right ventricle, and the pulmonary trunk arises from the left ventricle

Question 5

In which pathology is the heart positioned on the right side of the chest instead of the left?

Answer 5

Dextrocardia

Question 6

Which day does the cardiogenic mesoderm form?

Answer 6

Day 18

Question 7

Which day does the heart start beating in utero?

Answer 7

Day 22-23

Question 8

What are the 5 components of the heart tube during embryological development?

Answer 8

Truncus arteriosus

Bulbus cordis

Primitive ventricle

Primitive atrium

Sinus venosus

Question 9

In the growing heart tube, what does the truncus arteriosus become?

Answer 9

Ascending aorta and pulmonary trunk

Question 10

In the growing heart tube, what does the bulbus cordis become?

Answer 10

Parts of the outflow tract of both the left and right ventricles (may form parts of the right ventricle)

Question 11

In the growing heart tube, what does the primitive ventricle become?

Answer 11

Ventricles

Question 12

In the growing heart tube, what does the primitive atria become?

Answer 12

Rough walled parts of the left and right atria (e.g. auricle)

Question 13

In the growing heart tube, what does the sinus venosus become?

Answer 13

Smooth walled part of the right atrium

Question 14

What does the left horn of the sinus venosus become?

Answer 14

Coronary sinus

Question 15

What does the right horn of the sinus venosus become?

Answer 15

Smooth wall of the right atrium

Question 16

The endocardial cushion grows between what?

Answer 16

The dorsal and ventral walls of the atrioventricular canal

Question 17

The smooth part of the left atrial wall is formed by what?

Answer 17

By its growth into the pulmonary veins

Question 18

The atrial septum forms during which weeks?

Answer 18

Weeks 4 and 5

Question 19

Describe in detail the formation of the atrial septum.

Answer 19

19. The septum primum grows downward from the roof of the common atrium toward the endocardial cushion. There is a gap between the septum primum and the endocardial cushion called the foramen primum. As the septum primum continues to grow downward, it eventually fuses with the endocardial cushion, closing the foramen primum. Before the foramen primum closes completely, apoptosis occurs in the upper portion of the septum primum, creating perforations, which coalesce to form the foramen secundum. A second, thicker septum, called the septum secundum, begins to grow to the right of the septum primum. The septum secundum grows downward but does not completely fuse, leaving a small opening called the foramen ovale. The septum primum acts as a flap valve for the foramen ovale, ensuring unidirectional blood flow during foetal life

Question 20

What causes the foramen ovale to close?

Answer 20

Higher pressure in the left atrium pushed the septum primum against the septum secundum, forming the fossa ovalis

Question 21

During which movement can right-sided atrial blood pressure exceed that on the left, resulting in a small amount of venous blood passing into the left atrium in a probe-patent foramen ovale?

Answer 21

Valsalva manoeuvre

Question 22

Which test can be used to detect a patent foramen ovale?

Answer 22

Micro-bubble test

Question 23

The ventricular septum is composed of which 2 types of tissue?

Answer 23

Muscular and membranous tissue

Question 24

What are the 2 proposed causes of transposition of the great vessels?

Answer 24

Maldevelopment of conus arteriosus

Malformation of aorticopulmonary septum

Question 25

Which 2 things cause the closure of the ductus arteriosus after birth?

Answer 25

Increase in blood oxygen levels (PaO2) and decrease in prostaglandin E2 levels

Question 26

Aortic coarctation can be classified relative to its positional relationship to what?

Answer 26

Ductus arteriosus – preductal, juxtaductal, postductal