Flashcards in Cardiovascular 2 Deck (19)
What does the development of the endocardial cushions essentially split the heart into?
Right and left hand side.
Describe atrial Septation
- Septum primum grows downwards towards the endocardial cushion
- before it reaches it, there is a hole in it called the ostium primum
- before the ostium primum closes, a second hole called the ostium secundum forms in the septum primum
- a second down growth , a crescent shape, then occurs which is called the septum secundum.
- there is a hole in the septum secundum called the foramen ovale.
Blood can flow from the right atrium into the left atrium via the foramen ovale. (Part of the foetal shunts).
How does the foramen ovale close and what is its remnant in adult life?
It closes when the LA pressure >> RA - IE when the baby is born, takes its first breaths and decreases pulmonary resistance, so blood flows through the lungs so RA pressure decreases.
The fossa ovalis is the adult remnant.
What constitutes the ventricular septum
Muscular portion (mainly) and membranous portion.
What is the inter ventricular foramen and how is this plugged?
The foramen is the space left when the muscular portion of the ventricular septum forms, but doesn't grow all the way to the endocardial cushion. It's filled by the membranous portion of the septum, formed from connective tissue.
What forms from the truncus arteriosus?
The pulmonary artery and the aorta.
If the truncus arteriosus is one outflow vessel, how does it split into two?
Endocardial cushions appear in the truncus arteriosus also, which form a septum. However they must ensure the aorta is attached to left ventricle and PA to the RV. The septum takes a spiral course which (usually) ensures the connection of the correct chambers.
What is the adult structure formed from the:
A) sinus venosus
B) primitive atrium
D) bulboventricular sulcus
E) bulbus cord is
A) right atrium except left horn (recedes)
B) auricles of definitive atria
C) left ventricles
D) primary inter ventricular foramen
E) RV(trabeculated), outflow tract of L+RV and roots of aorta and PA.
What is an ASD, where does it normally occur and is it cyanotic? Explain your answer.
Atrial septal defect
Post natal communication between LA and RA
Usually occurs at foramen ovale
LA pressure >> RA pressure so oxygenated blood shunts to RA.
This then goes to the lungs to get oxygenated with other blood in RA.
- no deoxygenated blood enters the circulation so acyanotic.
What is paradoxical embolism and how does this occur?
This is when an embolism may enter the systemic circulation via a PFO.
If the RA pressure >> LA pressure then if there is an embolism in the RA, it can enter the LA and hence the system circulation.
Why doesn't a PFO sometimes cause signs and symptoms ?
Clinically silent usually as the LA pressure >> RA pressure.
Where does a VSD typically occur?
Which way will blood flow?
Cyanotic - T/F - why?
Typically occurs in the membranous portion of the inter ventricular septum.
Flows left to right as the LV pressure >> RV pressure.
Acyanotic as no deoxygenated blood enters the LV.
What is Eisdenmenger syndrome and how does it come about? Cyanotic or not?
Initially VSD occurs which allows L to R shunting
- increases blood flow through a low pressure system
- increase blood in pulmonary capillaries then increases pulmonary pressure
- pulmonary capillaries get damaged and replaced with scar tissue
- increases pressure further but doesn't aid oxygenation in lungs
- RV and RA hypertrophy due to increase pulmonary pressure
- eventually RV >> LV so the shunt reverses and deoxygenated blood flows into LV.
- this makes it cyanotic.
Discuss coarctation of the aorta.
Narrowing of the aorta distal to the branches of the arch, usually around the ligamentum arteriosum.
Upper limb and head blood unaffected as these branch proximal to the narrowing.
After load increased due to narrowing so LV can hypertrophy and heart failure can occur.
Upper body hypertension will lower body hypotension will be apparent.
Radial-femoral will be apparent. If the coarctation is proximal to the left subclavian vein, then the radial pulses will be asynchronous.
Tetralogy of fallot
Occurs due to the outflow portion of the inter ventricular septum too anterior and Cephalad.
- Overriding aorta
- pulmonary stenosis
- RV hypertrophy (due to pulmonary stenosis)
Cyanotic as RV pressure >> LV pressure and so therefore blood shunts right to left.
Tricuspid atresia - blood flow directions
RA - shunted to LA - LV - aorta - pda - PA - lungs - PV - LA - LV - aorta - body/pda
Transposition one great arteries
Aorta connected to RV
PA connected to LA
Not compatible with life. Needs ASD or PDA.
Hypoplastic left heart.
LV and ascending aorta not formed properly
Shunt from left to right
Deoxygenated blood pumped around the body.