Cardiac embryology Karina & Allison

What we are going to cover… Cardiac embryology Septal formation: atrial, ventricular and arterial outflow Heart defects 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. Heart is initially situated above the head then through longitudinal folding it moves into the adult position 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… Left Horn Of Sinus Right Horn Of sinus Sinus Venosus Bulbus Cordis Truncus Arteriosus Aortic sac Atria Ventricle Smooth wall of right atria Rough wall of both atria Ventricles Mainly outflow of ventricles Initial part of aorta & pulmonary trunk

And then what happens? Pulmonary veins grow out of the left atrial wall and branch. The proximal parts get absorbed into the atrial wall = smooth part Coronary sinus Vena Cavae LA LV Outflow Aorta RA RA Outflow Pulm Trunk RV Septum between left and right sides of the heart. 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 Shunting takes place to avoid the developing lungs. Which direction does this happen in? Coronary sinus Vena Cavae LA LV Outflow Aorta RA RA RV Outflow Pulm Trunk R  L shunting

What is this called? TA BC V Normal A SV Dextrocardia Dextrocardia

Atrial Septum: Days 24-35

Atrial Septum Septum primum RA LA Foramen primum Endocardial cushion Foramen secundum RA LA Septum secundum RA LA Endocardinal cushion grow across the AV canal from anterior to posterior. The cushion is a swelling in mesenchyme. Septum secundum RA LA Valve of Foramen ovale Foramen ovale

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 As soon as they take their first breathe the foramen ovale closes as the pressure changes. RA LA The septum secundum is muscular and stiff The septum primum is relatively floppy – it acts as a valve cusp

Sometimes fusion of foramen ovale does not occur 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. Test using micro bubble test (ultrasound).

Ventricular Septum. Day 35-42. What three things come together to form the ventricular septum? Muscle, membrane and endocardial cushion Which of these three parts is most likely to go wrong? Two membranous ridges grow down Membranous part Endocardial cushion Muscular septum

Common ventricular outflow septum. Day 35. A P A P What are the ridges derived from? Septum forms in truncus arteriosus and bulbus cordis Neural crest mesenchyme Septum spirals through ____o creating the aorta and the pulmonary trunk 180

Name all the defects.. Defects Which ones are cyanotic? Truncus arteriosus Ventricular septal Tetraology of fallot Atrial septal Transposition the great vessels Critical pulmonary stenosis Patent ductus arteriosus Which ones are cyanotic? To be coloured blue or red

What is this defect? Patent ductus arteriosus

Truncus arteriosus. What are the two types? Failure of bulbar ridge formation Failure of equal division

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? VSD Overriding aorta RV hypertropy Pulmonary stenosis The heart has been vorped…

Cardiac Embryology Timeline

Name the main cardiac embryology events…