Heart Development Lecture (just defects/pathology) Flashcards
Atrial Septal Defects
most ASDs result in initial (post birth) left to right shunting of blood b/c of increased blood flow returning from lungs & decreased pulmonary resistance after lungs expand
What is the result of an atrial septal defect?
shunting to R side of heart over time leads to abnormal increased blood flow to lungs
leads to pulmonary damage & pulmonary congestion, RV hypertrophy
ultimately leads to congestive heart failure
Why would cyanosis appear in an atrial septal defect?
hypertrophy of RV leads to a right to left shunt of blood so get mixing of blood
Ostium II/High atrial septal defect
90% of ASDs
hole in atrial septum caused by excessive absorption of septum I or inadequate of septum II
formaen ovale is still open
Ostium I/Low atrial septal defect
failure of up-growth of AV cushion tissue from AV septum & DMP to fill in ostium primum
have a patent ostium primum
What happens if no septa are formed?
common atria
How does cyanosis present?
clubbing of fingers
bluish fingernail beds & lips
fatigue
What does cyanosis represent?
deoyxgenated blood mixing w/ oxygenated blood where lowers overall O2 content
low O2 saturation of blood that is insufficient for normal tissue physiology
What causes a double outlet right ventricle?
mal-alignment defect from insufficient shifting of AV septum or cardiac looping
both aorta & pulmonary artery exit via RV accoompanied by a ventricular septum defect
Symptoms of Double Outlet Right Ventricle
present w/ in a few days w/ cyanosis, breathlessness, murmur & poor weight gain
What is the cause of ventricular septal defects (VSD)?
failure of proper closure by abnormal or inadequate fibrous tissue
Describe the progression of a VSD
starts as L to R shunt but becomes cyanotic post birth as RV hypertrophies due to increased work load
increase RV pressure exceeds left side so now get a R to L shunt
What does complete closure of the interventricular septum require?
downgrowth of AV septum
proper formation of conotruncal ridges
interventricular muscular septum formation
What causes persistent truncus arteriosus?
failure of contruncal ridge formation & fusion (outflow tract doesn’t get divided so still have opening between ventricles)
leads to VSD b/c undivided truncus overrides the R & L venticles
What does persistent truncus arteriosus present with?
pulmonary congestion
RV hypertrophy
increased R ventricular pressure
cyanotic conditions
What is tetralogy of Fallot and what are the consequences?
conotruncal ridges form off-center & leads to unequal division of pulmonary trunk & aorta
VSD (missing fibrous portion)
pulmonary infundibular stenosis
overriding aorta
RV hypertrophies in fetus
What is the most common cyanotic presenting heart defect in newborns?
Tetralogy of Fallot
b/c RV hypertrophies in the fetus due to a very small pulmonary opening
What causes transposition of great vessels & what are the consequences?
conotruncal ridges fail to spiral down
pulmonary A is connected to LV & aorta connected to RV
will only survive w/ existing shunts (VSD, ASD, patent ductus arteriosus)
What is pulmonary valvular atresia & what are the consequences?
semilunar valves are fused which leads to RV hypoplasia since the open foramen ovale is the only outlet for blood to get from R to L side
ductus arteriosus is only route for blood to get to lungs
What is aortic valvular stenosis and what are the consequences?
narrowing of aortic valve
leads to hypertrophy of LV & cardiac failure & pulmonary hypertension
What causes aortic valvular stenosis?
congenital
infection
degenerative changes in heart
What is the significance of a bicuspid aortic valve?
aortic valve only has 2 leaflets instead of 3
results in regugitation & then to stenosis w/ aging
will eventually lead to LV hypertrophy (some develop aortic aneurysm)
What is the cause of aortic valvular atresia & what are the consequences?
aortic valves are completely fused so have hypoplastic LV
leads to wide ductus arteriosus b/c only way for O2 rich blood to gt to L side & systemic circulation
What does an aortic valvular atresia produce in the fetus v post birth?
leads to RV hypertrophy in fetus
O2 blood enters RA via ASD & enters systemic circ via patent ductus arteriosus
What occurs with a tricuspid atresia?
tricuspid valve is closed (obliteration of right AV orifice) so blood in RA can’t move into RV
keeps foramen ovale open, get a VSD & hypoplastic RV, hypertrophy of LV & patent ductus arteriosus
What is seen with a hypoplastic left ventricle?
LV underdeveloped w/ absent or small bicuspid & aortic valves
ascending portion of aorta also be underdeveloped
open ductus arteriosus & foramen ovale (so can get blood to L side of heart & to lungs)
What is significant in pt with hypoplastic left ventricle?
heart works as uni-ventricular heart w/ RV doing all of the work
