Heart Development Lecture (just defects/pathology)

Question 1

Atrial Septal Defects

Answer 1

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

Question 2

What is the result of an atrial septal defect?

Answer 2

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

Question 3

Why would cyanosis appear in an atrial septal defect?

Answer 3

hypertrophy of RV leads to a right to left shunt of blood so get mixing of blood

Question 4

Ostium II/High atrial septal defect

Answer 4

90% of ASDs

hole in atrial septum caused by excessive absorption of septum I or inadequate of septum II

formaen ovale is still open

Question 5

Ostium I/Low atrial septal defect

Answer 5

failure of up-growth of AV cushion tissue from AV septum & DMP to fill in ostium primum

have a patent ostium primum

Question 6

What happens if no septa are formed?

Answer 6

common atria

Question 7

How does cyanosis present?

Answer 7

clubbing of fingers
bluish fingernail beds & lips
fatigue

Question 8

What does cyanosis represent?

Answer 8

deoyxgenated blood mixing w/ oxygenated blood where lowers overall O2 content

low O2 saturation of blood that is insufficient for normal tissue physiology

Question 9

What causes a double outlet right ventricle?

Answer 9

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

Question 10

Symptoms of Double Outlet Right Ventricle

Answer 10

present w/ in a few days w/ cyanosis, breathlessness, murmur & poor weight gain

Question 11

What is the cause of ventricular septal defects (VSD)?

Answer 11

failure of proper closure by abnormal or inadequate fibrous tissue

Question 12

Describe the progression of a VSD

Answer 12

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

Question 13

What does complete closure of the interventricular septum require?

Answer 13

downgrowth of AV septum

proper formation of conotruncal ridges

interventricular muscular septum formation

Question 14

What causes persistent truncus arteriosus?

Answer 14

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

Question 15

What does persistent truncus arteriosus present with?

Answer 15

pulmonary congestion
RV hypertrophy
increased R ventricular pressure
cyanotic conditions

Question 16

What is tetralogy of Fallot and what are the consequences?

Answer 16

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

Question 17

What is the most common cyanotic presenting heart defect in newborns?

Answer 17

Tetralogy of Fallot

b/c RV hypertrophies in the fetus due to a very small pulmonary opening

Question 18

What causes transposition of great vessels & what are the consequences?

Answer 18

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)

Question 19

What is pulmonary valvular atresia & what are the consequences?

Answer 19

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

Question 20

What is aortic valvular stenosis and what are the consequences?

Answer 20

narrowing of aortic valve

leads to hypertrophy of LV & cardiac failure & pulmonary hypertension

Question 21

What causes aortic valvular stenosis?

Answer 21

congenital
infection
degenerative changes in heart

Question 22

What is the significance of a bicuspid aortic valve?

Answer 22

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)

Question 23

What is the cause of aortic valvular atresia & what are the consequences?

Answer 23

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

Question 24

What does an aortic valvular atresia produce in the fetus v post birth?

Answer 24

leads to RV hypertrophy in fetus

O2 blood enters RA via ASD & enters systemic circ via patent ductus arteriosus

Question 25

What occurs with a tricuspid atresia?

Answer 25

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

Question 26

What is seen with a hypoplastic left ventricle?

Answer 26

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)

Question 27

What is significant in pt with hypoplastic left ventricle?

Answer 27

heart works as uni-ventricular heart w/ RV doing all of the work