Development of the heart Flashcards
- Ductus venosus: shunts blood from WHAT to WHAT (bypassing WHAT)
- Foramen ovale: shunts blood from WHAT to WHAT (bypassing WHAT circulation)
- Ductus arteriosus: shunts blood from WHA to WHAT (bypassing WHAT)
- Ductus venosus: shunts blood from umbilical vein to IVC (bypassing liver)
- Foramen ovale: shunts blood from RA to LA (bypassing pulmonary circulation)
- Ductus arteriosus: shunts blood from pulmonary trunk to ascending aorta (bypassing lungs)
Tetralogy of Fallot is comprimised of which 4 heart defects/
- Ventricular septal defect
- Overriding Aorta: aorta is positioned above the VSD
- Pulmonary stenosis (narrowing)
- Right ventricular hypertrophy
Explain the process of the formation of the atrial septum [5]
- Septum starts to grow from top of atria towards the endocardial cushion = septum primum.
- Ostium primum is the hole between septum primum and the endocardial cushion, so it gets smaller as the septum primum grows.
- But before the ostium primum closes completely, get a second whole: ostium secundum
- Septum secundum grows as a second sheet, but always has a whole within it (its not complete)
- Foramen ovale: valve formed between septum primum and the septum secundum
What is transposition of the Great Vessels?
Spiral structure that separates the outflow tracts has formed, but not as a spiral – instead as a flat sheet:
- left ventricle is connected to pulm. trunk and right ventricle is connected to ascending aorta
Why does the primitive heart tube begin to fold in length while it is growing? [1]
Which direction does this folding occur for the primitve ventricle [1] and primiritve atria? [1]
Why is this clinically important? [1]
Why does the primitive heart tube begin to fold in length while it is growing? [1]
Restricted by the pericardium
Which direction does this folding occur in? [1]
Primitive ventricle pushed to the left
Primitive atria move behind and above PV
Why is this clinically important? [1]
If looping occurs to the right: dextrocardia
Which of the following is the truncus arteriosus?
A
B
C
D
E
Which of the following is the truncus arteriosus?
A
B
C
D
E
What are acyanotic heart lesions characterised by? [1]
Name 4 acyanotic heart lesions [4]
What are acyanotic heart lesions characterised by? [1]
Group of cardiac diseases with a Left-to-Right shunt or left heart abnormality which do not result in cyanosis (blue skin colour) of the baby.
Name 4 acyanotic heart lesions [4]
oASD - Atrial Septal Defects
oVSD - Ventricular Septal Defects
oPDA - Patent Ductus Arteriosus
oCoarctation of the aorta
What are atrial septal defects caused by? [1]
Which population seen more in? [1]
Atrial septal defect (ASD):
- not the foramen ovale failing to form!!
- caused by the septum primum and secundum failing to form: no valve, just a hole – which then cant subsequently close.
- seen 2:1 female: male
How does ventricular septation occur? [2]
What is ventricular septal defect caused by? [1]
How does ventricular septation occur? [2]
Muscular portion grows superiorly towards endocardial cushion
Membranous portion grows inferiorly towards muscular component
They fuse together
What is ventricular septal defect caused by? [1]
VSD: Majority caused by membranous portion (that grows down) failing to fuse
What is patent ducutus arteriosus caused by? [1]
What does blood flow occur if this occurs from the arch of aorta? [3]
How do you treat? [2]
Patent ductus ateriosus caused by ductus ateriosus not closing.
Causes blood to flow from arch of aorta –> PDA –> Pulm. Trunk –> Lungs
Treatment: prostaglandin inhibitor, such as ibuprofen; surgery
What are cynatic heart lesions? [1]
Give one example [1]
Cyanotic congenital heart disease: a group of cardiac diseases which allow deoxygenated blood to bypass the lungs and enter the systemic circulation therefore the tissues of the body have less oxygen than they require and the baby is cyanosed (blue).
E.g. tetralogy of Fallot
Between which chambers does the foramen ovale shunt blood between? [1]
Why does this change after birth? [1]
Between which chambers does the foramen ovale shunt blood between?
Right atrium –> Left atrium [1]
Why does this change after birth?
After birth: lungs inflate with air, right hand side pressure drops – so is at a lower pressure = valve closes [1]
What is persistant trucus arteriosus? [2]
Spiral structure doesn’t form in truncus arteriosus: one common outflow tract. Both L & R ventricle pump into same outflow tract [1]
A large VSD (ventricular septal defect) below the truncal valve allows mixing of right and left ventricular blood [1]
Which of the following is the sinus venosus?
A
B
C
D
E
Which of the following is the sinus venosus?
A
B
C
D
E
What is the first cardiac structure to form in embryo? [1]
What do these fuse together to form? [1]
What is the first cardiac structure to form in embryo? [1]
blood islands
What do these fuse together to form? [1]
two endocardial heart tubes - which then folds laterally into one paired endocardial tube
What occurs to the blood pressure in upper and lower limbs w/ coarctation of the aorta? [2]
Bc blood is pumped from LV into arch of aorta and 3 great vessels
high bp before coarctiation: high / normal pressure in upper limps
low bp after point: low bp in lower limbs
How does septum formation occur in the atrio-ventricular canal?
- Two swellings of mesenchymal tissue appear from walls of the canal: endocardial cushions
- Endocardial cushions grow and fuse together – causing the atrioventricular canal to divide into left and right atrioventricular canal.
(But at this stage still only have one atria and one ventricle – need to form atrial and ventricular septums)
What is coarction of the aorta? [1]
In which two locations can this occur? [2]
What is coarction of the aorta? [1]
Defect caused by narrowing of aorta (stenosis of aorta)
In which two locations can this occur? [2]
- *- preductal coarctation of the aorta
- postductal coarctation of the aorta**
Which of the following is the primitive ventricle?
A
B
C
D
E
Which of the following is the primitive ventricle?
A
B
C
D
E
Which of the following is the bulbous cordis?
A
B
C
D
E
Which of the following is the bulbous cordis?
A
B
C
D
E
How does outflow tract septation occur to split the truncus ateriosus and bulbus cordis into two?
Truncoconal swellings form in the truncus arteriosus and grow towards each other in a spiral structure
Label this xx
Which of the following is the primitive atria?
A
B
C
D
E
Which of the following is the primitive atria?
A
B
C
D
E
