Embryology

Question 1

congential heart defects

incidence?
causes?

Answer 1

6-8 : 1000
Single gene mutation
chromosomal abn
Teratogens 
Infections eg rubella 
most multifactorial 

ECHO from 16 weeks

Question 2

Dextrocardia can be with or without sinus inversus

What does that mean?

Which is worse?

Answer 2

if sinus inversus - transposition of all abdominal viscera including the hear the heart is usually normal

If the rest of the organs are normal but just the heart is dextrocardia- this is usually associated with cardiac defects

Question 3

CHD

ASD vs VSD

Answer 3

ASD F>M
Small isolated patent ASD if no haemodynamic compromise is no biggie
25% of people have a probe patent ASD

VSD
25 % of CHD is VSD
M>F
Many close spontenously
If open massive L to R shunting and hypoxia.

Question 4

What are the 4 abnormalities is the teratology of fallot

Answer 4

VSD
Dextroposition of the aorta
Pulmonary stenosis
R venticular hypertrophy

Question 5

Vascular structures that are shunts for the fetal circulation

Answer 5

Ductus ventosus
bypasses the liver (50% of the blood)
Umbilical vein to IVC

foramen ovale - most from the R atrium goes through the Foramen ovale which is from RA to LA
Guided by the crita dividens

Ductus arteriosus 
From the pulmonary artery to the aorta 
The blood from RA - RV - Pulmonary artery to the lungs which is a very high resistance system 
10% to the lung
90% to the DA

Question 6

When do the shunts close ?

Answer 6

Formamen ovale
Immediately as the RA pressure drops as the pulmonary system pressures drop
A physiological closure occurs
This fuses over in time

Ductus arteriosis
Oxygen stimulates the closure of the DA
It closes at 10-15 hours
There is a small shunting of blood before then from the aorta to the pulmonary circuit.
A complication of rubella infection is a patent ductus arteriosis (PDA)

Ductus venosis
Closes immediately as the pressure from the umbilical vein drops as the cord is clamped
It has a sphincter that constricts

Question 7

What do the shunts become?

Ductus arteriosis

Ductus venosis

umbilical artery and vein

Answer 7

Umbilical vein - round ligament of the liver (ligamentum teres)

DV - ligamentum venosum - from the portal vein to the IVC

Umbilical artery - Medial umbilical ligaments
(proximal part the superior vesical arteries)

DA - ligamentum Arteriosum

Question 8

What is the incidence of a birth defect?

major and minor

Answer 8

3% - major structural anomalies

The incidence of a birth defect is 6% in 2 year olds and 8% in 5 year olds

50% unknown etiology
1/3 genetic factors
Minor defects in 14% of the population

Question 9

What are the layers of the endometrium

Answer 9

functional layer (sheds)
compact
spongy layer - edemous connective tissue with the body of the glands

basal layer - blind ends of uterine glands

Question 10

Meiosis

What are the phases

Answer 10

In meiosis there is phase 1 and 2

Chromosomes go from diploid to haploid