4 - cardiac abnormalities Flashcards
at what stage does the heart develop?
heart development is during the foetal and neonatal stage, failure in transition can result in cardiac abnormality
what causes ventricular septal defect (VSD)?
- the superior part of the ventricular septum fails to form causing blood to mix between ventricles
- more blood is shunted from the left to the right because the left ventricle is stronger
what causes coarctation of the aorta?
- a part of the aorta is narrowed, increasing the workload of left ventricle
- occurs at birth
- can be pre or post ductal coaction
- it encourages collateral circulation
what causes tetralogy of fallot?
multiple defects within the heart structure (4)
- pulmonary trunk too narrow and pulmonary valve stenosed, resulting in
- hypertrophied right ventricle
- ventricular septal defect (hole between ventricles)
- aorta opens from both ventricles (overriding aorta)
circulation during the foetal stage?
- oxygen is supplied by placenta via the umbilical arteries
- lungs are fluid filled and there is a great resistance to blood flow
- oxygenated blood needs to enter the left side of the heart for systemic circulation
- the right side of the heart has higher pressure than the left
circulation during the neonate stage?
- the various foetal openings and shunts need to be closed
- the left side of the heart has a higher pressure than the right
- failure to close or error in development may result in cardiac abnormality
what are the developmental steps of the heart?
- heart develops from a single muscular tube at 22 days
- then develops into 4 chambers and needs to function as both foetal and neonatal heart
what are the developmental steps of the atria?
- the septum primum starts to grow and separates the single atrium into 2, blood flows through the ostium primum right to left
- the septum primum joins to the endocardial cushion, the ostium secundum are made in septum primum to allow blood circulation
- the septum secundum forms with foreman ovale to allow foetal circulation to continue
what happens during the development of the ventricles?
- the single ventricle is divided into two by the growth of a septum
- if the septum fails to grow and join with the endocardial cushion or part of the septum is reabsorbed, then a hole will be present
- this hole is a ventricular septal defect (VSD)
what is the difference between cyanotic and acyanotic abnormalities?
cyanotic - is when deoxygenated blood enters the systemic circulation
acyanotic - is when oxygenation of the systemic circulation is relatively normal (some oxygenated blood re-enter the pulmonary circulation)
what are some examples of acyanotic abnormalities?
- ventricular septal defects (VSD’s)
- atrial septal defects (ASD’s)
- aortic stenosis
coarctation of the aorta
what are some examples of cyanotic abnormalities?
- tetralogy of fallot
- transpostiton of the great vessels
what causes atrial septal defect (ASD)?
- the septum primum may be too short and unable to ver the foreman ovale
- the foreman ovale may be too large due to a failure of the septum secundum to grow down far enough
what is Patent Ductus Arteriosus?
it is a condition where the ductus arteriosus fails to close after birth
- blood will flow from the higher pressure aorta to the lower pressure polmonary artery
- this will reduce blood flow via aorta and systemic circulation
- increasing blood flow to lungs causing polmonary oedema, resulting on right sided heart failure
how does the formation of the aorta & pulmonary artery occur?
- the truncus arteriosus, needs to be divided into the aorta and pulmonary artery
- they must then line up with the correct ventricles
- the truncus ateriosus must spiral 180 degrees
- failure to spiral results in transposition of the great vessels
- failure to split equally results in a stenotic (narrowed) aorta or pulmonary artery
