Congenital Heart Disease & Foetal Circulation Flashcards
Describe how the inclusion of the placenta changes how the foetal organs function in comparison to an adult body?
The placenta plays a role in
- Gas exchange/ Nutrition/ Waste excretion
=> lungs are fluid filled and unexpanded
=> liver has little role in nutrition and waste management
=> gut is not in use
How is the placenta joined to the foetal circulation?
Foetal heart pumps blood to the placenta via:
- umbilical arteries (FOETUS TO MUM)
Blood from the placenta flows to the foetus via:
- umbilical vein (MUM TO FOETUS)
What 3 shunts are specific for foetal life and why?
Ductus venosus
Foramen Ovale
Ductus Arteriosus
- needed as the oxygenated blood needs to be distributed from the RHS of the heart
Where is the ductus venosus found and what is its role?
- Connects umbilical vein to the IVC
=> blood flows INTO foetus from MUM and takes this route to the heart
Where is the foramen ovale located and what is its job?
Opening in atrial septum connecting RA to LA
=> oxygenated blood can easily flow into the LV and be distributed around the baby’s body
What is the function of the ductus arteriosus and where is it found?
- Connects pulmonary bifurcation to the aorta
- allows more O2 blood to be shunted to the systemic circ. rather than travelling to immature lungs
What allows the ductus arteriosus to remain patent?
- circulating prostaglandin E2
- this is produced by the placenta
Describe how the foetal circulation changes in the first few minutes after birth?
- Pulmonary Vasc. Resistance DECREASES
- Baby breathes in – lungs expand => lower pressure
- More of the cardiac output sent to lungs
- Systemic Vasc. Resistance INCREASES
- Cord clamped and cut
What forces the foramen ovale to close?
- Systemic vascular resistance increases
=> LA pressure increases and eventually exceeds RA pressure and closes the flap
The foramen ovale can remain open in what percentage of people?
Up to 35%
A patent foramen ovale is a risk in what conditions?
Stroke
Migraine
How long does it take for the ductus arteriosus to close after birth?
- Functional closure within hours to days
- Anatomical closure within 7-10 days
- Ends up as fibrous ligament
What prompts the closure of the patent ductus arteriosus
- Decreased flow due to DECREASED pulmonary vasc. resistance
- Decreased prostaglandins (PGE2) due to increased lung metabolism
- Shunt becomes bidirectional then left to right before closing
The ductus arteriosus can remain patent in certain infants. TRUE/FALSE?
TRUE
- very common in preterm infants
How can a patent ductus arteriosus be treated?
- wait and see
- NSAIDs
- surgery
Some congenital heart diseases, e.g. Aortic Interruption, cause a “duct dependent circulation”. How do we keep the duct open to maintain their circulation?
IV prostaglandin E2
- used to keep the duct open until an alternative shunt established or definitive surgery carried out
What is meant by Persistent pulmonary hypertension of the newborn (PPHN)?
Failure of adaptation from foetal to adult circulation
=> Lung vascular resistance fails to fall
=> Shunts remain
=> Blue baby
How is PPHN investigated?
Pre and post ductal Oxygen sats
- large difference between these
- Pre = R hand and Post = L foot
How is PPHN treated?
- Ventilation
- oxygenation
- inhaled nitric oxide
- ECLS
Describe the spectrum of congenital heart disease severity.
Mild – asymptomatic, may resolve spontaneously OR may progress
e.g. small VSD, ASD, PDA, PFO or bicuspid aortic valve
Moderate – specialist intervention and monitoring in a cardiac centre
e.g. aortic valve disease, larger complex ASD/VSD
Severe – present severely ill, die in newborn period/ early infancy
MAJOR – surgery within 1st year of life
How does congenital heart disease present?
- At Screening (Antenatal/ Newborn baby check)
- Well baby with clinical signs
- Unwell baby
=> Cyanosis/ Shock/ Cardiac failure
When can congenital heart disease present?
- antenatally
- Soon after birth => Cyanosis
- Day 1-2 => Murmurs, abnormal pulses, cyanosis
- Day 3-7 => circulatory collapse, shock, cyanosis, death
- 4-6 weeks => cardiac failure - poor feeding, failure to thrive, SOB, sweaty
- 6-8 week GP check => incidental murmur
An incidental murmur heard at a newborn baby check may not be pathological. TRUE/FALSE?
TRUE
- May be a small muscular VSD
=> Causes a murmur early in life
=> No consequences, Many close spontaneously
What is cyanosis and what causes this?
- condition where mixed oxygenated and deoxygenated blood enters the systemic circulation from the heart
- causes bluish discolouration
What are the main differential diagnoses for cyanosis in a newborn baby?
- Cardiac disease
- Respiratory disease
- Persistent pulmonary hypertension of the newborn (PPHN)
How can you attempt to work out the cause for a baby’s cyanosis?
Cardiac babies = blue with little or no respiratory distress
Respiratory = associated with increased work of breathing, X-Ray changes
PPHN = Large pre-post ductal differential
What circulations are considered as “duct dependent”?
Duct dependent systemic:
- Hypoplastic left heart
- critical aortic stenosis
- interrupted aortic arch
- critical coarctation of aorta
Duct dependent pulmonary:
- Tricuspid atresia
- Pulmonary atresia
What is pulmonary atresia?
Pulmonary trunk from RV does not form properly
- PDA still exists therefore blood backflows from aorta to pulmonary arteries
What clinical signs indicate failure in babies?
- Failure to thrive
- Slow / reduced feeding
- Breathlessness (especially when feeding)
- Sweatiness
- Hepatomegaly
- Crepitations
What are the consequences of a moderate -> large VSD?
- often no murmur at baby check
- Murmur develops as pulmonary pressures drop over first weeks
- Increased pulmonary circulation
- congestive cardiac failure
What is involved in the longer term management of major cardiac diseases?
Surgery
- Repair vs palliation
- Valves, stenosis
- Transplant
- Developmental problems may occur
- Hypoxia
How is a PDA repaired surgically?
- catheter procedure
- uses device to close this
- device is left in and followed up on1
How is VSD repaired surgically?
- with a patch
How is Hypoplastic left heart treated?
- 3 Stage complex surgery
- Significant mortality at each stage and between
- Ends with RV supplying systemic circulation
- Will fail over time
- Then Transplant is required
What happens in Transposition of the Great Vessels?
LV connected to pulmonary trunk
RV connected to Aorta
=> baby becomes cyanotic
