S4 Congenital Heart Defects Flashcards
What are the 3 general causes of congenital heart defects?
- Genetic e.g. Down’s, Turner’s and Marfan’s syndromes
- Environmental e.g. drugs, alcohol, etc (malformation of embryo)
- Maternal infections e.g. rubella
What is the normal oxygen saturation in each part of heart in a child (so slightly lower than in adults)?
- R atrium - 67%
- R ventricle - 67%
- pulmonary trunk - 67%
- L atrium - 99%
- L ventricle - 99%
- aorta - 99%
What is the normal pressure in each part of heart in a child (so slightly lower than in adults) in mmHg?
- R atrium - /4
- R ventricle - 25/3
- pulmonary trunk - 25/10
- L atrium - /5
- L ventricle - 80/4
- aorta - 80/40
Where the nominator is systole and the denominator is diastole
What congenital heart defects are acyanotic?
- ASD, VSD an PDA (left to right shunts)
- aortic stenosis (hypoplasia), pulmonary stenosis (valve/outflow/branch), coarction of the aorta, mitral stenosis (obstructive lesions)
What congenital heart defects are cyanotic?
- tetralogy of fallot
- transposition of the great arteries
- total anomalous pulmonary venous drainage
- univentricular heart
Right to left shunts
Where are the 4 places you can get shunts?
- Between atria
- Between ventricles
- Atrioventricular
- Aorto-pulmonary (ductal)
What are the haemodynamics effects of a left to right shunt?
It requires a hole.
Blood from the left heart is returned to the lungs instead of going to the body.
Increased lung blood flow isn’t damaging but increased pulmonary artery/pulmonary venous pressure is damaging.
What are the haemodynamics effects of a right to left shunt?
Requires a hole and a distal obstruction.
Deoxygenated blood bypasses the lungs
What are the haemodynamic effects of an atrial septal defect (ASD)?
- increased pulmonary blood flow
- right ventricle volume overload
- pulmonary hypertension (rare)
- eventual right heart failure
No mixing of deoxygenated and oxygenated blood pumped around the systemic circulation
What are the haemodynamic effects of an ventricular septal defect (VSD)?
- left to right shunt
- left ventricle volume overload
- pulmonary venous congestion
- eventual pulmonary hypertension
Which congenital heart defect is most common in those with Down’s syndrome?
Atrioventricular septal defects (35-40% those with Down’s syndrome that have a congenital heart defect have this one)
What is coarctation?
Narrowing of the aorta
What are the haemodynamic effects of coarction of the aorta?
Narrowing of aortic lumen in ligamentum arteriosum region (used to be ductus arteriosus)
- increases after load on the left ventricle
- left ventricular hypertrophy
- vessels to head and upper limbs aren’t compromised
- vessels to rest of body, blood flow is reduced
The extent of symptoms depends on the severity of the coarction
What is a patent foramen ovale (PFO)?
Present in around 20% of the population and are generally clinically silent as the higher left atrial pressure causes functional closure of the flap valve
What is patent ductus arteriosus (PDA)?
Failure to close the ductus arteriosus
Blood flows from aorta to pulmonary artery after birth (high to low pressure) - left to right
Doesn’t cause cyanosis but can cause problems later on if untreated
What is tetralogy of Fallot? What are the four anomalies?
4 lesions occurring together to result in a single developmental defect (outflow portion of interventricular septum too far in the anterior and cephalad directions)
Right to left shunting occurs (deoxygenated blood into systemic circulation)
- VSD
- Overriding aorta
- Pulmonary stenosis
- Right ventricular hypertrophy
What is tricuspid atresia?
Lack of development of the tricuspid valve
So no inlet to the right ventricle
Results in complete right to left shunt of all blood returning to the right atrium (via a ASD or PFO) and then a VSD or PDA is needed to allow blood flow to the lungs
These can be made after birth to allow blood flow in the right direction (surgery)
What is transposition of the great arteries?
Results in two unconnected parallel circulations instead of two circulations in series.
The right ventricle is connected to the aorta and the left ventricle to the pulmonary trunk
Need surgery to put in a shunt between the left and right sides e.g atrial shunt
What is hypoplastic left heart?
When the left ventricle is underdeveloped resulting also in a small ascending aorta
To help, the right ventricle supports systemic circulation
There has to be a right to left shunt (need a ASD and PDA)
What is a univentricular heart?
Only one ventricle (VSD)
Can be present with or without transposition of the great arteries
What is a pulmonary atresia?
When there is no right ventricle outlet
So a right to left atrial shunt of the whole venous return is needed
Blood flows to the lungs via a PDA
Which congenital heart defects are present in infancy/early childhood?
VSD, coarction, tetralogy of fallot
Results in left heart failure in infancy, if untreated can lead to an in-operable pulmonary hypertension (VSD)
Associated with PDA and right to left shunt in neonates (coarctation)
Cyanotic spells in infancy and early childhood (tetralogy of fallot)
Which congenital heart defects are result as a neonatal emergency?
Transposition, hypoplastic left heart, pre-ductal coarctation and pulmonary atresia
Due to reduced pulmonary blood flow
Which congenital heart defect is usually asymptomatic until late in adulthood?
ASD which results in late onset arrhythmia and right heart failure
Coarctation in adults results in complicated renal hypertension, left ventricle hypertrophy associated with aortic valve stenosis
Some mild cases of tetralogy of fallot are compatible with adulthood
