Development Of The Heart Flashcards
Which germ layer does the cardiovascular system develop from
Mesoderm
What does the heart develop from
Cardiogenic mesoderm
What do angiogenic cell clusters in the cardiogenic mesoderm coalesce to form
Left and right endocardial tubes
What causes the endocardia tubes to fuse into the primitive heart tube
Lateral folding of embryo
What does the truncus arteriosus become
Proximal aorta and pulmonary artery
What does the bulbous cordis become
Ventricular outflow tracts and right ventricle
What does the primitive ventricle become
Left ventricle
What does the primitive atria become
Left and right atria
What does the sinus venosus become
Smooth part of right atrium and coronary sinus
What parts of the heart are present at 21 days gestation
Truncus arteriosus
Bulbous cordis
Primitive ventricle
Primitive atria
Sinus venosus
Why does the primitive heart tube fold as it lengthens
Length limited by pericardium
What causes the chambers and vessels of the heart to align during gestation
Folding of primitive heart tube
When does the primitive heart tube fold
Days 23 - 28
What connects the atrium and ventricle at 35 days
Atrioventricular canal
What are the endocardial cushions and when do they form
2 swellings of mesenchymal tissue from walls of atrioventricular canal
28 days
What does the septum of the atrioventricular canal form from
Endocardial cushions
Where does the foramen ovale shunt blood from and too
Taught atrium to left atrium
Why does the foramen ovale fuse after birth
Higher pressure in left atrium than right atrium
Are atrial septal defects more common in males or females
Females
2 parts of atrial septum
Septum premium
Septum secondum
When does the muscular interventricular septum develop
End of 4th week
Where does the muscular interventricular septum grow from and towards
From floor of primordial ventricle
Towards membranous interventricular septum
What does the membranous interventricular septum form from
Endocardial cushions
What is the most common type of cardiac defect
Ventricular septal defect
What proportion of ventricular septal defects are in the membranous septum
90%
Where and when do the truncoconal swellings form
Truncus arteriosus
5th wk
Why do the truncoconal swellings grow towards each other in a spiral
So aorta connects to LV and pulmonary ventricle to RV
What does the ductus venodud shunt blood between
Umbilical vein to IVC
What does the foramen ovale shunt blood between
RA to LA
What does the ductus arteriosus shunt blood between
Pulmonary trunk to ascending aorta
What structure allows foetal blood to bypass the liver
Ductus venosus
What structure allows foetal blood to bypass the pulmonary circulation
Foramen ovale
What structure allows foetal blood to bypass the lungs
Ductus arteriosus - Pulmonary trunk to ascending aorta
What does the ductus venosus fibrosis to form
Ligamentum venosus/teres
What does the foramen ovale close to form
Fossa ovalis
What does the ductus arteriosus fibrose to form
Ligamentum arteriosum
Acyanotic congenital heart disease
Group of cardiac diseases with a left to right shunt or left heart abnormality which do not result in cyanosis
Patent ductus arteriosus
Ductus arteriosus does not close postnatally
What does a patent ductus arteriosus increase risk for
Bacterial endocarditis
Patent ductus arteriosus treatment
Prostaglandin inhibitor - eg ibuprofen
Surgical closure with clip - If not closed by 3 months
Coarctation of the aorta
Constriction of aorta
What is the difference between pre ductal and post ductal coarctation of the aorta
Pre ductal occurs above ductus arteriosus
post ductal below ductus arteriosus
What allows blood flow in pre ductal aortic coarctation
Ductus arteriosus persists
What allows blood flow in post ductal coarctation of the aorta
Collateral circulations establish
How is blood pressure affected by coarctation of the aorta
High bp before coarctation
Low bp after coarctation
Cyanosis heart lesions
Group of cardiac diseases which allow deoxygenated blood to bypass lungs and enter systemic circulation causing cyanosis
What defects comprise tetralogy of fallot
Ventricular septal defect
Overriding aorta
Pulmonary stenosis
Right ventricular hypertrophy
Persistent truncus arteriosus
Single truncus arises from heart supplying both aorta and pulmonary artery, large VSD below truncus valve allows blood in LV and RV to mix
Features of persistent truncus arteriosus
Variable degree of cyanosis
Presents with progressive heart failure
Transposition of the great ventricles
Aorta and pulmonary arteries switched
What causes transposition of the great vessels
Conotruncal septum runs straight down instead of spiralling
What is transposition of the great vessels usually accompanied by
Open ductus arteriosus
Transposition of great vessels treatment
Immediate surgical catheterisation of fossa ovalis to increase mixing of pulmonary and systemic blood
Further surgery at later date
Acyanotic heart lesion examples
Atrial septal defects
Ventricular septal defects
Patent ductus arteriosus
Coarctation of the aorta
Cyanosis heart lesion examples
Tetralogy of fallot
Transposition of the great vessels
Patent truncus arteriosus
