Embryology and Congenital Heart Defects

Cardiovascular anatomy lecture 1

What day does heart development start?

20 days post-conception

Which cells begin heart development ?

cardiac progenitor

Which is the first heart structure formed

the heart tube

Describe the ends of the heart tube?

there’s the superior arterial end and the inferior venous end

How many layers does the heart tube have?

the heart tube is formed of the endocardium, myocardium and pericardium

When does cardiac looping take place

day 23 ish - day 28

What are the different stages of cardiac looping?

folds into a C shape

then folds into an S shape

what day does the heart tube differentiate into sections

day 21

What sections does the heart tube differentiate into (from arterial end to venous end)?

aortic sac

truncus arteriosus

bulbus cordis

primitive ventricle

primitive atrium

sinus venosus

Describe the sections of the bulbus cordis

truncus arteriosus

conus cordis

proximal third

What does the truncus arteriosus develop into

aorta and pulmonary artery

Name the congenital condition where the truncus arteriosus doesn’t separate properly?

truncus arteriosus

What does the conus cordis of the bulbus cordis develop into?

smooth outflow tracts of both ventricles

What does the proximal 1/3 of the bulbus cordis develop into?

muscular right ventricle

What does the primitive ventricle develop into

left ventricle

What does the primitive atria develop into

RA and LA

What does the sinus venosus develop into

Superior and inferior vena cava

coronary sinus

some RA

Which septums form with the folding of the heart tube?

atrioventricular septum

aorticopulmonary septum

interventricular septum

What structure exists in the interatrial septum

foramen ovale

What is the function of the foramen ovale ?

Blood is oxygenated through the placenta into the RA.

FO allows oxygenated blood from the RA to flow to the LA to avoid the lungs which aren’t functional.

What happens to the foramen ovale at birth?

pressure changes cause flap to seal shut, forming the fossa ovalis

What condition is it when the foramen ovale doesn’t shut?

patent foramen ovale (PFO)

What is PFO an example of ?

atrial septal defect (ASD)

What percentage of people have a PFO?

around 25%

What are the consequences of a PFO?

LA to RA shunting,

Right heart volume overload (paradoxical IVS motion)

pulmonary hypertension

Which major strucures are present in foetal heart that are not in adult heart?

open foramen ovale

open ductus arteriosus

What structure exists between the descending aorta and the pulmonary trunk ?

ductus arteriosus

What is the purpose of the ductus arteriosus

enables oxygenated blood leaving the RA into the pulmonary trunk to cross into the aorta.

necessary as lungs aren’t involved in gas exchange

What should happen to the ductus arteriosus after birth?

it should close, becoming the ligamentum arteriosum

What condition arises when ductus arteriosus remains open

patent ductus arteriosus

Tetralogy of Fallot is what type of CHD?

VSD

What are the four features of tetralogy of Fallot

1. pulmonary stenosis

2. overriding aorta (aorta connects to LV and RV) fed by both LV ad R

3. VSD

4. right ventricular hypertrophy

What is the most common form of CHD?

ASD

What are the different types of ASD?

secundum ASD

primium ASD

superior sinus venosus ASD

inferior sinus venosus ASD

What are secundum ASDs

ASDs which occur in the middle of the IAS wall usually around the foramen ovale

Not necessarily central but have to have some IAS superiorly and inferiorly.

what are primium ASDs

ASD occurring right at the bottom of the IAS at the MV/TV level

so on the inferior border there is no more IAS surrounding

What’s the term for when a PFO that closes on its own but after the normal post-birth period?

spontaneous closure