Heart Development Flashcards
What are the two sources of mesenchyme in the outflow tract?
NCC : ectoderm
Endocardial Cushion tissue : splanchnic mesoderm
What causes a persistence of the AV canal?
failure of AV septum to form from lack of migration of ECT
What does a persistent of the AV canal result in and what is strongly linked with it?
- ASD and VSD as cushion tissue from AV septum contributes to fibrous portion of both
- abnormal Genesis of AV valves
- Down’s syndrome
What is the consequence of having of persistent AV canal?
- pulmonary hypertension
- intolerance to exercise
- SOB
- cardiac congestion
- increase risk of endocarditis
What is the occurrence of atrial septal defects?
who does it affect more : male or female?
6:10,000
female 2:1
What are the 3 causes of atrial septal defects?
Which is most common?
1) Ostium 2 / high atrial septal defect
2) Common atria (no septa formed)
3) Ostium 1 / low atrial septal defect
high atrial is more common
What happens to cause a high atrial septa defect?
1) Excessive absorption of septum 1 forms and overly large osmium 2
OR
2) inadequate development of septum 2
What causes a low atrial septal defect ?
-failure of upgrowth of the AV cushion tissue from AV septum and DMP fail to fill in osmium 1
What is the occurrence of Ventricular septal defects?
12-15/10,000
What is the major cause of ventricular septal defects ?
failure to close via inadequate/abnormal fibrous tissue
What is required to get complete interventricular separation?
1) fusion of the conotruncal ridges
2) fusion of the ridges with the AV septum
3) down growth of ECT from the AV septum
Describe blood flow of VSD and how it relates to cyanosis
Starts : ACYANOTIC : L->R shunt ; eventually pressure build b/c of RV hypertrophy so now have R -> L shunt
Ends : CYANOTIC ; R -> L shunt
What is the occurrence of persistent trunks arteriosus?
1/10,000
What causes persistent truncus arteriosus?
What does it result in?
- failure of formation and fusion of the conotruncal ridges
- pulmonary a. and aortic valve share common opening into both ventricles
- pulmonary a. further up on truncus
- mix of O2 and deOs blood
What are the consequences of persistent truncus arteriosus?
- pulmonary congestion
- VSD
- CYANOSIS (due to RV hypertrophy)
What causes tetralogy of Fallout ?
What 4 things does it result in?
conotruncal ridges form off center and unequal
1) VSD (missing fibrous portion)
2) pulmonary a. stenosis
3) overriding aorta (open to both ventricles)
4) cyanosis (RV hypertrophy) (R->L shunt)
What is the most common cause of cyanosis at birth?
Tetralogy of Fallout
What causes pulmonary valvular atresia?
What occurs in response to the atresia?
-fusion of pulmonary valves leading to RV hypo-trophy
- > patent foramen ovalis = get blood from R -> L
- > patent ductus arteriosus = get blood to lungs
What is aortic valvular stenosis?
What causes it?
How many people does it affect and male or females more?
- narrowing of the aortic valve
- 1) congenital 2) infection (rheumatic fever) 3) degenerative
- 1-2% of population
- males 4:1 females
What is aortic valvular atresia?
What is its consequence?
-aortic valve fused and LV is underdeveloped
1) wide ductus arteriosus (get blood to L side and systemic)
2) RV hypertrophy fetally
3) after birth : ASD allows blood to enter RA and Ductus arteriosus to systemic
What is Bicuspid Aortic Valve?
What is its consequence?
2 rather than 3 leaflets due to fusion of 2 of them (1-2% population)
- regurgitatoin or later stenosis
- eventual LV hypertrophy
What is having a bicuspid aortic valve associated with?
aortic aneurysm
What is tricuspid atresia?
-obliteration of right AV orifice (tricuspid valve)
What are the consequences of Tricuspid atresia?
1) patent foramen ovalis (get blood to systemic)
2) VSD (sometimes)
3) Underdevelped RV
4) LV hypertrophy
5) patent ductus arteriosus (get blood to pulmonary)
What is a hypoplastic Left Ventricle ?
2-3/10,000
-LV is underdeveloped w/ absent bicuspid and aortic valves
What are the consequences of a hypoplastic LV?
- underdeveloped ascending aorta
- patent ductus arteriosus (blood to systemic)
- patent foramen ovals (from lungs to R side)
-Heart works univentricularly)
What is transplantation of the great vessels?
consequence?
5/10,000
-conotruncal ridges fail to spiral
-Aorta w/ RV and pulmonary a. with LV
Are those with transplantation of the great vessels able to survive?
Yes, b/c of ASD,VSD, and patent ductus
keep ductus arteriosus open for exchange via prostaglandin inhibitors
