Cardiac embryology

Karina & Allison

What we are going to cover…

1. Cardiac embryology2. Septal formation: atrial, ventricular and

arterial outflow3. Heart defects4. Timeline of cardiac development

What type of folding moves the brain, mouth and heart into the adult position? And when does this happen?

Longitudinal folding. Day 19.

Green line = position of the heart

What is this called? And what is its clinical significance?

Transverse pericardial sinus Sits between arterial outflow & venous input

Significance: clamp off arterial flow during surgery.

Dilations appear in the heart tube.Name them…

Dilations appear in the heart tube.Name them…

AtriaSinus

Venosus VentricleBulbus Cordis

Truncus Arteriosus

Smooth wall of right atria

Rough wall of both

atria

Ventricles Mainly outflow of ventricles

Initial part of aorta & pulmonary trunk

Aortic sac

Left HornOf Sinus

Right HornOf sinus

And then what happens?

LARA

LV Outflow

Coronary sinus

Vena Cavae

Aorta

RA RV Outflow Pulm Trunk

Pulmonary veins grow out of the left atrial wall and branch. The proximal parts get absorbed into the atrial wall = smooth part

Septa form and divide chambers and outflow tract to create the left right sides of the heart

Shunting takes place to avoid the developing lungs. Which direction does this happen in?

• R L shunting

LARA

LV Outflow

Coronary sinus

Vena Cavae

Aorta

RA RV Outflow Pulm Trunk

What is this called?

Dextrocardia

BCVA

SV

TA

Normal

Dextrocardia

Atrial Septum: Days 24-35

Atrial Septum Septum primum

Foramen primum

Septum secundum

Septum secundum

Foramen ovale

Foramen secundum

RA

RA

RA

RA

LA

LA

LA

LAValve of Foramen ovale

Endocardial cushion

What is the function of the foramen ovale in the fetus?

• Lungs are fluid filled with high pulmonary resistance.

• Want to avoid them • Therefore blood is shunted through the

foramen ovale from R L

RA LA

The septum primum is relatively floppy – it acts as a valve cusp

The septum secundum is muscular and stiff

Sometimes fusion of foramen ovale does not occur. What problems could this cause in later life?

• Valsava maneuver can briefly increase right sided pressure over left

• This opens the foramen ovale • Can result in emboli passing from right atria to

left atria• Increases possibility of TIA and stroke.

Ventricular Septum. Day 35-42.• What three things come together to form the

ventricular septum?

Two membranous ridges grow down

Muscular septumEndocardial cushion

Which of these three parts is most likely to go wrong?

Muscle, membrane and endocardial cushion

Membranous part

Common ventricular outflow septum. Day 35.

AP

A P

PA

Septum forms in truncus arteriosus and

bulbus cordis

Septum spirals through ____o creating the aorta and the pulmonary trunk

What are the ridges derived from?

Neural crest mesenchyme

180

Name all the defects..

Defects

Truncus arteriosus

Ventricular septal

Tetraology of fallot

Atrial septalTransposition

the great vessels

Critical pulmonary

stenosis

Patent ductus

arteriosus

Which ones are cyanotic?

What is this defect?

Patent ductus arteriosus

Truncus arteriosus. What are the two types?

Failure of equal division Failure of bulbar ridge formation

What is this defect?

• Transposition of great vessels – 2 isolated circulations

• What other defect can be good to have in this condition to help compensate?

Patent ductus arteriosus

Multiple cardiac defects can occur together in the tetraology of fallot. What are the 4 components?

1. VSD 2. Overriding aorta 3. RV hypertropy 4. Pulmonary stenosis

The heart has been vorped…

Cardiac Embryology Timeline

Name the main cardiac embryology events…