Cardiology Flashcards
What are the shunts of the foetal circulation?
Blood is transferred between mother and baby via the placenta.
Blood enters the foetal circulation through the umbilical vein.
Shunts are in place since the lungs are filled with amniotic fluid and not developed fully functionally.
Blood bypasses the liver (from the umbilical vein) into the RA via the inferior vena cava.
Small amount of blood will pass into the right ventricle* but majority will pass into the left atria via foramen ovale. LA blood will move to LV then the aorta.
Blood from the RV will pass to the PA but bypasses the pulmonary circulation through the ductus arteriosus; where in enters the aorta.
All blood from the aorta will go to supply the body.
How are the shunts closed functionally?
Umbilical cords are clamped off so no supply via the umbilical vein. DV closes.
Baby takes first breath, pressure in the lungs drops. Now LA pressure>RA pressure. FO closes.
Prostaglandins are needed to keep DA open. Increased blood oxygenation causes drop in circulating prostaglandins. DA closes.
What is PDA?
Patent ductus arteriosus.
Normal DA closes within first 1-3 days and will have closed by 2-3 wks. Some baby’s wont close- cause unknown but RF include maternal rubella or premature.
DA remains patent- since pressure in aorta is greater than pulmonary artery- blood flows into the pulmonary artery- increased load- pulmonary HTN- more blood in the RH- increased RH strain- RVH- more blood returning to and straining the LH- LVH.
How does PDA present?
Can be asymptomatic and picked up later in life with features of HF.
Newborn baby with severe PDA will present with a murmur. Normal first heart sound, then crescendo-decrescendo murmur running over the second heart sound, making it difficult to hear the second heart sound. Difficulty feeding Poor weight gain SOB LRTI
How is PDA diagnosed?
How is PDA managed?
Diagnosed with echocardiogram.
Monitor with echo until age 1yrs.
After 1yrs old, unlikely to spontaneously close; trans-catheter or surgical closure.
If symptomatic or severe PDA then treat earlier.
What are ASD?
Atrial septum made from septum secundum and septum primum. If these remain patent to give ostium secundum (most common), patent formane ovale (not technically an ASD) or ostium primum (least common), this is known as an ASD.
ASD- LA>RA pressure- blood flows into RA- increase load of RH- Pul HTN + RSHF.
Overtime Pul HTN will be greater than systemic pressure- the shunt will switch- RA>LA pressure so blood will flow from the RH to the LH- patient becomes cyanotic. This is known as Eisenmenger’s syndrome.
What are the complications of ASD?
Stroke- Usually VTE will enter the RA and then pulmonary circulation. But can pass into the LA and through the aorta into the brain causing serious stroke.
AF/flutter
RSHF and Pul HTN
Eisenmenger syndrome
How does ASD present?
Detect antenatally and at birth.
Can be asymptomatic.
Present with new-born murmur mid-systolic crescendo-decrescendo. The first heart sound is heard, the second heart sound is fixed split. Normally the heart sound will split on inspiration, in ASD there is more blood in the RH and so it takes longer to empty the RH than the left. The pulmonary valve will therefore always close after the aortic valve leading to a split second heart sound.
Babies/younger children will present with SOB, LRTI, difficulty feeding and poor weight gain.
Adulthood (if childhood asymptomatic) will present with dyspnoea, HF or stroke.
How is ASD managed?
Need referral to paediatric cardiologist.
Closure with transvenous catheter or surgery.
Need anticoagulation.
What is a VSD?
Small hole or absence of the entire ventricular septum.
Commonly associated with Down’s syndrome and Turner’s syndrome.
LV>RV pressure- blood moves from LV to RV- increase load of RH- Pul HTN and RSHF.
Overtime Pul HTN>systemic pressure- blood moves from RV to LV- patient becomes cyanotic. (Eisenmengers syndrome)
How does VSD present?
Can often be asymptomatic.
Can see antenatally or notice a pan systolic murmur with systolic thrill at birth.
Children can present with dyspnoea, tachypnoea, failure to thrive, difficulty feeding.
How is VSD managed?
Small holes with no symptoms or features of RSHF + P-HTN- can just watch and wait.
More serious defects will need transvenous catheter or open surgery closure.
During surgery Pt are at risk of developing infective endocarditis so should be given prophylactic Abx.
What is Eisenmenger’s syndrome?
Pul HTN > systemic pressure therefore structural defects L-R shunts will reverse to become R-L shunts- leading to cyanosis.
Associated with ASD, VSD and PDA.
Life expectancy is reduced by 20yrs. Can develop earlier in life with a larger shunt, smaller shunt will usually present in later life with Eisenmenger’s.
Shunt can progress quickly into Eisenmenger’s in pregnancy- mortality of 50%.
How does Eisenmenger’s syndrome present?
Symptoms of Pul HTN- Raised JVP Peripheral oedema Right ventricular hives Loud second heart sound (P2)- Pulmonary valve is closed harshly under more pressure.
Symptoms of structural defect-
ASD- mid-systolic murmur cresendo-decrescendo
VSD- pansystolic murmur- heard best at left sternal broder.
PDA- machinery continuous crescendo-decrescendo murmur
Symptoms of R-L shunting- Cyanosis Plethora- Since have cyanosis- need more - O2 - body makes more RBC - increase blood viscosity - polycythaemia- increased risk of VTE Clubbing Dyspnoea
How is Eisenmenger’s syndrome managed?
Should reverse the structural defect once it’s noticed.
Once a R-L shunt forms, this condition is irreversible.
Need a heart-lung transplant; has a high mortality.
Medical management- O2 for dyspnoea Venesection for polycythaemia Viagra for pul HTN Arrhythmia treatment Anticoagulation Prophylactic Abx for infective endocarditis
