5.04 - congenital heart problems + DS

-Source of oxygen: fetus - placental, adult - lungs
-pulmonary shunts: foramen ovale, ductus arteriosus, ductus venosus

30-40 mmHg

1. no respiratory effort
2.no thermoregulation

hole in the inter-atrial septum

connection between the LEFT pulmonary trunk and the aorta (distal to the arch branches)

bypass vessel of the liver - allwos placental blood to bypass the liver

placent --> single umbilical vein --> 80% bypasses the iver via the ductus venosus and joins directly to the IVC (mixing of blood) --> right atrium --> most blood passes through the foramen ovale --> LA --> left ventricle --> aorta

Note: in the learning topics it said 50% of the blood bypasses the liver but lecture said 80%.
it also said about 50% of the blood passes through the foramen ovale. of the 50% that goes into the right ventricle only about 10% goes to the lungs.(different sources say different amounts - just know it isnt very much compared to adult which is 100%%%%)

deoxy blood from the fetus --> returns to the right atrium via the SVC and IVC (mixing of the blood) --> about 50% passes into the right ventricle --> pulmonary arteries --> most of the blood then flows via the ductus arteriosus into the aorta (doesnt enter the lungs because the pulm. circulation is under such high pressure) --> travels from descending aorta via internal iliac veins --> umbilical arteries (2) --> placenta

Note: the entry into the aorta is distal to the three branches of the aorta - the brain and top half of the body recieves more oxygenated blood supply than the bottom half.

2 angioblastic cords from from the mesoderm layer --> form 2 endocardial heart tubes --> fuse to form a single linear heart tube --> heart looping results in S shaped heart --> single outflow tract divides into 2 (pulmonary and aortic) --> partitioning septation (formation of the chambers)

19 days

22 days

4 weeks

no

outflow tract = bulbus cordis
distal outflow = truncus arteriosus

ventral --> outer border
dorsal --> inner border

2 spiral truncoconal ridges buldge into the lumen and meet seperating it into 2 --> forms the aorticpulmonary septum

-derived from neural crest mesenchyme

~5 weeks

~ 5 weeks

-atrioventricular septum
-interventricular septum
-inter-atrial septum

7 weeks

endocardial cushion

-posterior and anterior walls of the endocardial cushions grow together and fuse at the midline

-separate the atrium from the ventricles

50%

-membranous part of the IV septum grows DOWN from the endocardial cushion
-muscular part of the IV septum grows UPWARD from a fold the apex

Divides the left and right ventricles

left

-septum primum grows down and fuses w endo cushion
-initially it is cresent shapped and thus get a gap = foramen primum
-programmed cell death to form a foramen secundum as the septum fuses with the cushion
-2nd septum grows down (on the right) called the septum secundum
-it also develops with a hole = foramen ovale

The two holes allow for the passage of blood

the formaen ovale acts as a valve
-as fetus - higher pressure in the right thus blood flows through R--> L (bypassing the lungs)
-as adult - (LA>RA pressure --> septum pressed closed)

septum primum

TRICKY!

1%

VSD!

yep thats right ellie

1/200 live births
-30% in isolation
-70% with other cardiac defects

failure of fusion between the membranous and the muscular parts of the ventricular septum

failure of the membranous part of the VSD to descend far enough

90%

-most close spontaneously in childhood (partic. if in muscular region)
-surgical correction is implicated iwht there is a large L--> R shunt because it can lead to irreversible pulmonary vascular damage
-surgery usually performed at 1-2 years

-pulmonary disease
-infective bacterial endocarditis (tricuspid and aortic valves in particular)

1/250 births in australia

-excessive absorption of tissue around the foramen secundum
-hyperplastic growth of the septum secundum


note: less commonly caused by lack of union between septum primum and the endocardial cushion

25% - most asymptomatic

-related to strokes (including paradoxical embolus)
-migraines
-decompression sickness (in diving)

Ligamentum arteriosum

arteriosus constricts due to:
-increased arterial oxygen
-decreased pulm. vascular resistance
-decreased local PGE2

note: often delayed in hypoxic neonates --> this can be benificial e.g. in TOF

haha i could be asking you the consequecnes of public displays of affection??

complications of patent ductus arteriosis:
-pulmonary HT
- obstructive pulm. vascular disease (destruction of capillaries and thickening of arteries)
- reversal of shunt (Eisenmengers) --> cyanosis
-massive RV hypertrophy

continuous harsh machinery like murmur

1. high VSD
2. overiding aorta (aorta lies over the IV septum)
3. pulmonary stenosis
4. RV hypertrophy

TOF

degree of pulmonary stenosis?
-mild obstruction: left--> right shunt. no cyanosis (signif. amount of blood enters lung)
-severe obstruction: right --> left shunt. severe cyanosis (most deoxy blood from the RV passes from the RV--> LV and into systemic circulation via the VSD and doesnt get oxygenated)

-xray: boot shaped heart (due to RV hypertrophy and upturning of the LV and also decreased cardiac shadow on the upper left due to pulm. trunk stenosis)

may also get:
-polycythaemia (due to chronic hypoxia)
-PDA (this is benificial)

-Blalock Taussig shunt until corrective surgey
-the blalock taussig shunt involves taking a branch of the subclavian or carotid artery and connected it to pulmonary artery (it is effectively created a similar shunt to the PDA)
-surgery involves graft to open pulmonary tract

50% dead by 2.5 years

congenital L to R shunt e.g. PDA --> blood flows rom high pressure left circulation to the right --> increase pressure in the pulmonary vasculature - eventually leading to irreversible pulm. vascular damage (capillary destruction and scaring and thickening of the pulmonary arteries) --> increased pulmonary pressure --> increase right heart pressure and hypertrophy --> eventually the right pressue>left --> reversal of shunt to R to L shunt (cyanosis)

1. left to right shunt (late cyanosis) e.g. VSD, PDA
2. right to left shunt (cyanosis at birth) e.g. TOF, transposition of the great vessels
3. obstructive lesions with no cyanosis e.g. aortic coarctation, stenosis of the pulm. and aortic vessels

i think there are probably other ways to classify the heart defects but if you didnt get what i was talking about youre probs going to FAIL and have to do this whole year again!

-right lessions e.g. pulmonary atresia, tricuspid/pulm stenosis, absent pulm artery
-transposition of the great vessels
-coarctation of the aorta
-left side lessions e.g. aortic atresia, mitral/aortic stenosis

1/2000 live births (note 50% have other malformations as well)

distal to branches of aortic arch

- internal mammary arteries (branch of the subclavian) anastomose with intercostals which anastomose with thoracic aorta

-dilated and turtuous mammary arteries
-hypertropied, turtuous intercostal arteries
-obvious entry points of the intercostal arteries into the descending aorta
-SAWTOOTH appearance of the ribs (seen on x-ray)

-distal to ligamentum arteriosum
consequences:
-LV hypertrophy
HT atherosclerosis of arch vessels

-pre-ductal
consequences
-ductus maintians patent --> RV hypertophy --> right heart failure

-2 or more SD in IQ below pop mean plus limitation in at least two areas of adaptive functioning e.g. self care, communication

1-3%

1. compression of small pulm. arteries by fluid filled alveoli
2. low resting alveolar and arterial PO2 - hypoxic environment =potent vasoconstrictor (in lungs)
3. circulating pulm. vasoconstrictors (prostaglandin F2alpha, thromboxane A2, endothelin)

circulating prostaglandins:
-PGE2
-prostacyclin

Foramen ovale:
-decreased size in final trimester

Ductus Arteriosus:
-wall becomes more muscular and change in the type of muscle (to become more contractile, and also less sensitive to prostaglandins)
(note: if baby born prematurely then some of these muscular changes may not have occured and thus increased liklihood that the duct will remain patent)

Fetal lung:
-becomes primed before and during labour by catecholamines, cortisol and T4 which become elevated in response to contractions and interupted blood supply

-stimulation of type II pneumocytes to produce surfactant
-shift of lungs from fluid producing to fluid absorbing
-increased blood supply to vital organs (brain, heart)
-mobilisation of fuel

1. commencement of breathing
- loss of fetal lung fluid
- secretion of surfactant
-establishment of FRC (functional residual capacity)
2. decrease in pulm. vascular resistance
3. increase in systemic vascular resistnace
4. closure of the three fetal systemic-pulmonary shunts

-hypoxaemia
-acidosis
-umbilical cord occlusion
-thermal changes

-most is expelled with first few breaths and the remainder is absorbed into the pulmonary lymphatics and capillaries

-expansion of lungs with air
-increased PO2 and decreased PCO2
-prostacylin and NO (pulm. vasodilators)

note: biggest decrease occurs in first 2-3 days and more gradual decrease by 2 weeks

-removal of the low resistance placental from circulation

-stimulation: increase in PO2 and changes in prostaglandin
-functional closure: 10-15 hours after birth
-permanent closure: 2-3 wks by combination of thrombosis, intimal prolif and fibrosis

closes functionally at birth (due to left pressure becoming greater than right pressure - forces valve closed

-commences shortly after birth
-complete within 3-7 days
-cause: due to cessation of umbilical venous return

-cyanosis
-respiratory distress
-cardiac failure
-shock

- parenchymal lung disease

-may have lung disease
-congenital heart disease

-congenital heart disease (likely to be ductal dependent)
-parenchymal lung disease (unlikely)

1. prematurity
2. persistent fetal circulation (persistent pulm. hypertension)
3. congenital heart disease

-often will still have a patent ductus arteriosus (becuase dont get changes in muscle etc. which are essential for the closure)

-perinatal asphyxia
-meconium aspiration pneumonia

-persistance of high right pressure --> thus persistance of right to left shunt through foramen ovale --> cyanosis

m - 61.1
f - 57.8

-dental problems
-constipation
-Gastrooesophageal reflux
-undiagnosed fracture

50% (learning topics say 40%)

if there is a discrepancy they should NOT be able to test us on it

AVSD

10%

-duodenal atresia
-hirchprungs disease

60%

-strabismus (squint)
-refractive errors (50%)
-cataracts (15%)
-keratoconus
-blepharoconjunctivitis

-children - conductive haering loss (due to serous otitis media)
-adults - sensorineural loss

-large tongue (this is why jean thought she had DS)
-narrow oropharynx
-obestity
-hypotonia

NONE - same overall risk

- childhood leukaemia:
- 10-20 fold increase
-usually first 5 years
-testicular cancer
-5 fold increase

-most have normal onset of puberty
-males:
-50% undescended testes (cryptorchidism) (stupid - the learning topics say 21%)
- most infertile
-females
-reduced fertility

7-11% (increased from general pop_

-hypotonia
-indulgence with food (because feel sorry for the child and because of aggressive behav. of the child if they dont get what they want)

7 fold

-alopecia
-vitiligo
-coeliac
-hypothyroidism

-hyperkeratosis
-seborrhoeic dermatitis

-depression (most common)
-OCD

-hearing
-vision
-thyroid function
-weight

4-6weeks

6-7 months

-hypotonia
-excessive skin folds at the back of the neck
-maxillary (malar) underdevelopment
-clinodactyly (curving of the little finder)
-hypoplasia of the middle phalanx of the 5th finger - short middle segment or single interphalangeal crease
-sandal gap (wide gap between first and second toes - i.e. kates foot)


Some other features
-epicanthic folds (this is what asian people have)
-single transverse palmar crease

MEEEEE!!!!!

-ID
-prominence of tongue
-flattening of back of head (brachycephaly)
-short stature
-bushfield spots (speckling around the rim of the iris)
-joint hypermobility

95%

-trisomy 21 - 95%
-translocation (robertsonian) - 2.5%
-mocaicism - 2.5%

-the non-segregation of paired sister chromatids to 2 daughter cells - this results in one germ cell with 24 chromosomes and one with 22

-non-disjunction during formation of germ cells - so that the germ cell has 2 chromosome 21s instead of 1. This germ cell then fuses with the other gamete with normal number of chromosomes. the resulting zygote has 3 chromosome 21s.

- 95% from the mother
-it is thought that because the paternal gamete has to compete to reach the egg that the faulty sperms are less competitive and are less likely to make it

a crhomosome with its centromere at one end:
- q is much longer than p (p has no functional genes on it)

remember p for petite

acrocentric chromosomes:
-13,14, 15, 21,22

20 - 1/1500
30 - 1/1000
40 - 1/100
45 - 1/30

Chromosome rearrangement formed by fusion of the whole long arms of two acrocentric chromosomes

-balanced: no excess or deficit of genetic material and causes no health difficulties

100%

-NONE will have downsyndrome (they have two copies of all importnat genes)
-10% of offspring will inherit DS

when there are two populations of cells with different genotypes in the one individual (who has developed form one single egg)

after fertilisation

-non-dysjunction in one of the cells of the dividing embryo leading to 3 chromosome 21 in subsequent divisions of that cell

1. arterial blood entering capillaries less saturated than normal
2. circulation slowed - thus more extraction of oxygen - and thus increased conc. of deoxy Hb in capillaries

-cold induced vasoconstriction
-reduced circulation due to narrowing e.g. athermatous narrowing

-arterial blood entering capillaries less saturated than normal

-primacy of patient welfare
-patient autonomy
-social justice

-the obligation to act in the clients interest even if it means foregoing business opportunities

severe mental retardation
small eyes, may exhibit a split in the iris (coloboma) cleft lip and/or palate
weak muscle tone (hypotonia)
increased risk of heart defects
skeletal abnormalities, and other problems

low birth weight
small abnormally shaped head
small jaw, small mouth
clenched fists with overlapping fingers
mental retardation,
heart defects, other organ malformations such that most systems of the body are affected

75%

25%