congenital cardiovascular disease Flashcards
how does the placenta carry blood to the foetus?
through the umbilical vein
where is 25% of blood diverted to in the feotus?
- where will the rest go?
the ductus venosis
- the remainder will be distributed to the liver via the portal vein and he hepatic portal system
what is the ductus venosus critical for?
delivering well-oxygenated blood to the left side of the foetal heart and thus to the coronary and cerebral circulation
what prevents a major portion of the cardiac output from entering the lungs?
high pulmonary vascular resistance in the foetus will prevent a major portion of the cardiac output from entering the lungs
- blood flow will be diverted to other organs via the Formen oval and the ductus arteriosus
describe the transition from neonatal to normal circulation?
- first breathe, pulmonary vascular resistance drops
- this reduced resistance results in increased flow through the pulmonary arteries
- causing an increase in pressure in the left atria and the abrupt reduction in the pressure on the right side of the heart.
- formane ovale closure
- blod no longer bypasses the pulmonary circulation
what are congenital heart defects?
- they are problems with the hearts structure that are present at birth
- they change the normal flow of blood through the heart
what percentage of live births have CHD?
0.8%
3 main types of CHD?
1- the interior walls of the heart
2- the valves inside the heart
3- the arteries and veins that carry blood to the heart or away from the heart to the body.
6 types of acyanotic CHD?
1- ventricular septal defect
2- atrial septal defect
3- pulmonary stenosis
4- aortic stenosis
5- correction of the aorta
6- patent ductus arteriosus
what are the 5 T’S for cyanotic CHD?
1- Tetralogy of Fallot
2- Total anomalous pulmonary venous return
3- Transposition of the great vessels
4- Tricuspid atresia
5- Truncus arteriosus
what are 2 other types of cyanotic CHD?
- hypoplastic left heart
- pulmonary atresia
3 examples of left to right shunts?
1- ventricular septal defect
2- atrial septal defect
3- patent ductus arteriosus
left to right shunts?
these are lesions that allow blood to shunt from the left to the right side of the heart
- they are associated with varying degrees of increased pulmonary blood flow and are typical acyanotic
- doesn’t eff t the proces of oxygenation in your lungs
examples of right to left shunts?
1- tetralogy of Fallot
2- transposition of the great arteries
3- pulmonary valve atresia
4- truncus arteriosus
5- tricuspid atresia
6- total anomalous pulmonary venous return
right to left shunt?
lesions that result in deoxygenated blood reaching the aorta.
examples of obstructive valvular and non valvular lesions?
- coarction of the aorta
- pulmonary valve stenosis
- aortic valve stenosis
what is the most common congenital heart defect?
ventricular septal defects
describe ventricular septal defects
- 20% of cases
- subtypes based on location of the defect
- small medium or large
what is the difference between small, medium and large ventricular septal defects?
small = don’t cause problems and may close on their own
medium = less likely to close on their own and may require treatment
large = allow a lot of blood to flow from the left to the right ventricle. this extra blood increase blood pressure in the right side of the heart and the lungs
if there is a larger ventricular septal defect, what signs of excess pulmonary blood flow may they experience?
- tachypnoea
- tachycardia
- pallor
- poor feeding
- poor weight gain
what happens if the whole doesn’t close in ventricular septal defect?
(the extra workload can cause heart failure and poor growth)
- if the whole doesn’t close, high blood pressure can scar the arteries in the lungs leading to pulmonary hypertension and irreversible damage causing shunt reversal and EISENMEGEsyndrome.
clinical signs of Ventricular septal defect?
- pan systolic murmur
- loud second heart sound
- heart failure
what clinical findings would you expect to see for ventricular septal defect?
- cardiac enlargement
- increased pulmonary vascular markings (CXR)
- left ventricle hypertrophy (ECG)
- an echo will show the defect itself.
how can you repair a medium/large ventricular septal defect?
- can be repaired using a catheter or open heart surgery
- large = diuretics and increased calories followed by closure
describe Patent Ductus arteriosus?
- 9 to 12% of all CHD
- 30 fold higher incidence in patients born in a higher altitude
what is PDA/
- persistent communication between the descending thoracic aorta and the pulmonary artery that results from failure of normal physiological closure of the foetal ductus.
- left to right shunt, the blood flows from the aorta to the pulmonary aorta
why is there a continuous murmur in PDA?
- as the pressure in the pulmonary artery is lower than in the aorta throughout the cardiac cycle
- this murmur is continuous because the thoracic pressure if higher than the pulmonary artery pressure during both systole and diastole.
what would you see in the clinical tests for PDA?
- ECG and CXR will be normal
- in a large PDA, you will see biventricular hypertrophy on the surface ECG
- in a large PDA, you will see increased pulmonary blood flow and cardiomegaly on CXR may be present
- echocardiograpghy allows delineation of the PDA anatomy and the direction and the volume of the shunt.
how to treat PDA in a newborn?
if there is significant respiratory distress or impaired systemic oxygen delivery, treat with intravenous indomethacin or ibuprofen
how to treat PDA in older children?
closure is recommended to avoid the risk of infective endocarditis, options are catheter closure or surgical ligation.
describe arterial septal defect?
- 6-10% (4 subtypes based on location of the defect)
- can be small, medium or large
small atrial septal defect?
allow only a little blood to leak from one atrium to the other
- they don’t effect how the heart works
- close on their own
medium and large atrial septal defects?
- allow more blood to leak from one atrium to the other
- don’t close on their own
if untreated what happens in ASD?
- leads to exercise intolerance and atrial arrhythmias in the third or fourth decade of life.
- people are often asymptomatic and this is the most commonly missed diagnosis
what are signs of ASD?
- no symptoms/ recurrent chest pain
- in moderate to large lesions:
= ejection systolic murmur
this murmur will be caused by increased blood flow through the pulmonary valve, not through the ASD
in ASD, what would the clinical signs be?
- CXR = normal
- ECG= normal (except in a larger lesion, there may be right atrial enlargement, right ventricular enlargement or right axis deviation)