Embryology and Congenital Heart Disease Flashcards
what layer is the heart derived from?
visceral mesoderm
What type of folding brings the heart to its final position?
Cranio-Caudal folding
Name the 4 heart tube regions from top to the bottom
Truncus Arteriosus
Bulbus Cordis
Ventricle
Atrium
what heart tube region is responsible for aorta and pulmonary trunk?
truncus arteriosus
what heart tube region is responsible for RV and outflow of both ventricles?
bulbus cordis
what heart tube region is responsible for LV?
ventricle
what heart tube region is responsible for both atria?
Atrium
How many dilatations does the heart tube develop?
5
What is the direction of BF through the primitive heart?
caudal to cranial
What are the right and left horns called in atrium?
sinus venosus
d: sinus venosus
smooth part R atrium
Coronary sinus
What happens to atrium heart tube in looping and folding?
becomes dorsal and cranial
What happens to ventricle heart tube in looping and folding?
displaced left
What happens to bulbus Cordis heart tube in looping and folding?
inferiorly, ventrally to right
f: the placenta in utero (8)
Fetal homeostasis Gas exchange Acid base balance Nutrient transport to fetus Waste product transport from fetus Hormone production Transport of IgG PGE2
How does the circulation differ in the fetus?
The placenta is included in the circulation: Gas exchange Nutrition Waste excretion Homeostasis
How do the lungs differ in the fetus?
they are unexpanded and fluid filled
How does the liver differ in the fetus?
has little role in nutrition and waste management
Is the gut in use in the fetus?
no
Describe fetal circulation route?
placenta to the R side of the heart to brain and body back to placenta etc
What arteries does the foetal heart use to pump blood to the placenta?
umbilical
How does blood from the placenta return to the foetus?
via umbilicial vein
How does oxygenated, nutrient rich blood return from the placenta to the right side of the heart and get distributed to the growing foetus?
3 “shunts” specific to foetal life:
Ductus venosus
Foramen Ovale
Ductus Arteriosus
what does the ductus venosus do?
connects the umbilical vein to the inferior vena cava
what does the foramen Ovale do?
opening in atrial septum connecting RA to LA
What does the ductus arteriosis do?
connects pulmonary bifurcation to descending aorta
WHere does the ductus venosus carry the majority of placental blood to and how?
straight into IVC bypassing portal circulation
where does the foetus get its nutrients?
placenta
Name 2 things the foramen ovale allows?
Allows blood to flow from right to left atrium
Allows the best oxygenated blood to enter left atrium then on to LV, ascending aorta, carotids
Membrane flap on left atrium side
what percentage of blood goes to the lungs in foetus? where does the rest go and how?
7%
The rest goes via ductus arteriosus to join descending aorta
How is patency maintained? how is this produced?
maintained by circulating prostaglandin E2 produced by placenta
what happens immediately after baby born?
Massive changes in the few minutes following birth
Baby inflates lungs and cries
Goes from blue to pink
Cord clamped and cut
describe the circulatory changes after birth?
Pulmonary Vascular Resistance decreases: -breath in - lungs -physically expand increased SV -cord clamped and cut more CO to the lungs foramen ovale close
why does the foramen ovale close?
As PVR falls and SVR rises the LA pressure exceeds the RA pressure
The flap is pushed closed
Describe the adaption of the ductus arteriosus after birth?
Functional closure within hours to days
Anatomical closure within 7-10 days
Ends up as fibrous ligament – ligamentum arteriosum
How does the ductus arteriosus constrict after birth?
Decreased flow due to decreased pulmonary vascular resistance
Increased pO2 – oxygen sensitive muscular layer
Decreased circulating PGE2 due to increased lung metabolism
Shunt becomes bidirectional then left to right
What babies more commonly have failure to close from ductus arteriosus?
preterms
treatments for failure of duct to close?
include wait and see, NSAIDs and surgery
How can duct be kept open for duct dependent circulation until surgery carried out?
IV prostaglandin E2 can be used to keep the duct open until an alternative shunt established
what happens to pulmonary resistance after birth?
continues to drop until reaches normal adult levels by 2-3months
Name some of the consequences failures of adaptation
Persistent pulmonary hypertension of the newborn
More likely in sick babies
Sepsis
Hypoxic ischaemic insult
Meconium aspiration syndrome
Cold stress
Can be related to underlying anatomical abnormality such as congenital diaphragmatic hernia
pathophysiology for Persistent pulmonary hypertension in newborn’s(PPHN)?
Lung vascular resistance fails to fall
Shunts remain
Right to left flow at PFO
Right to left flow at PDA
What colour are babys with PPHN?
BLUE
large/small difference between pre and post ductal O2 sats?
large
treatment of PPHN?
Ventilation, oxygenation, high systemic blood pressure, inhaled nitric oxide, ECLS
d: congenital heart disease
Abnormality of the structure of the heart or intrathoracic great vessels
Present at birth
How do you find congenital heart disease?
Screening -Antenatal -Newborn baby check Well baby with clinical signs Unwell baby -Cyanosis -Shock -Cardiac failure
describe the 3 grades of congenital heart disease?
Mild = asymptomatic, Moderate = specialist intervention, Severe = present severely ill, Major = Surgery in 1st year
Symptoms of congenital HD?
Unwell baby, cyanosis, shock, cardiac failure
What is done to predict congenital defects?
antenatal screening
d: blue baby syndrome
Cyanosis (blue baby) – anything where heart allows deoxygenated blood to enter circulation
name some of the differntial diagnoses for blue baby syndrome?
Differential: cardiac disease, resp. disease, Persistent Pulmonary Hypertension of the Newborn (PPHN)
Name the most common newborn cyanosis presenting example
transposition of great vessels
pulmonary and aortic vessels swapped
clinical signs of failure in babies?
- Failure to thrive
- Slow/ reduced feeding
- Breathlessness
- Sweatiness
- Hepatomegaly
- Crepitations
what is hypoplastic left heart?
left side of the heart underdeveloped
what is pulmonary atresia and what is it coupled with?
underdeveelopment of right ventriclular outflow
often with VSD
What is VSD?
ventricular septal defect
treatment of duct closure issues?
ABC – support airway and breathing as necessary
Prostaglandin E2 to open duct
Multisystem supportive treatment
Transfer to cardiac surgical centre for definitive management
name the duct dependent systemic circulation?
Hypoplastic left heart, critical aortic stenosis, interrupted aortic arch, critical coarctation of aorta
name the duct dependent pulmonary circulation
Tricuspid atresia
Pulmonary atresia
is there an initial murmur for large VSD?
Often no murmur at baby check
Murmur develops as pulmonary pressures drop over first weeks
if theres a big VSD what is the gradient more/less?
less
how is patent ductus arteriosus repaired?
cathether procedure
What does VSD repair require?
surgery
HLHS requires what for treatment?
3 Stage complex surgery
Significant mortality at each stage and between
Ends with RV supplying systemic circulation
Will fail over time
Transplant
