Lecture 8 Flashcards
What are some causes of congenital heart disease?
- Genetic (Down’s, Turner’s, Marfan’s syndrome:more likely to have a CHD)
- environmental (teratogenic drugs, alcohol)
- maternal infections (rubella, toxoplasmosis)
Does the pulmonary circulation have high/low resistance?
Low
What maintains the pumping of the heart?
- Pressure gradient
- Muscle pumping
What are the units for pressure?
mmHg (equivalent to cm)
What does relaxation of the right ventricle cause?
Cause a suction like motion helping the blood drain into it.
Pressure/pO2 reading in each chamber of the heart:
RA: 4mmHg, 67% pO2
RV: 3mmHg diastole/25 mmHg systole, 67% pO2
PT: 10mmHg diastole/25mmHg systole, 67% pO2
LA: 5 mmHg, 100% pO2
LV: 4mmHg diastole/80mmHg child/120mmHg adult systole
A: 40mmHg diastole/80mmHg systole
What is the effect of a L to R shunt?
- blood from left heart is returned to lungs instead of going to the body
- increased lung blood flow (not damaging alone), but increased pulmonary artery/venous pressure is
What is the effect of a R to L shunt?
De-oxygenated blood bypasses the lungs
What are the 2 classifications of CHD’s?
Acyanotic (don’t alter oxygen levels)
Cyanotic (systemic oxygen levels are lower)
What are some acyanotic CHD’s?
- L to R shunts
- obstructive lesions (aortic/pulmonary stenosis, mitral stenosis, coarctation of the aorta)
What is coarctation of the aorta?
Narrowing of the aorta (congenital), usually in area where the ductus arteriosus inserts.
-cyanotic
What are some cyanotic CHD’s?
Complex R to L shunts
- tetralogy of fallot
- transposition of great arteries
- univentricular heart
- total anomalous pulmonary venous drainage
What is total anomalous pulmonary venous drainage?
All 4 pulmonary veins don’t connect normally to LA
-instead they drain oxygenated blood into the superior vena cava so oxygen rich blood isn’t going to the body
What do atrial septal defects cause?
hole b/w the atria
L-R shunt
- increased pulmonary flow (pressure not increased)
- RV volume overload
- eventual right heart failure
What do ventricular septal defects cause?
L-R shunt
- pulmonary venous congestion (extra blood into lungs)
- eventual pulmonary hypertension
- LV volume overload (due to increase in BP in RV, therefore increased pulmonary flow= LV overload)
What is an atrio-ventricular septal defect?
Can’t separate the side of the heart.
What is aortic stenosis?
Narrowing of aortic valve opening, restricting blood flow, could lead to increase in pressure of left ventricle/atrium
What causes lots of defects in the tetralogy of fallot?
Over-rotation causes aorta to be further right
What is tricuspid atresia and its effects?
Tricuspid heart valve is missing/ under developed.
- no RV inlet
- R-L atrial shunt of entire venous return
- blood flow to lungs via ventricular septal defect or patent ductus arteriosus (blood high pressure in aorta so oxygenated blood would move back to pulmonary arteries)
What does transposition of the great arteries cause?
- causes the systemic & pulmonary circulation to become separate
- requires a bi-directional shunt
How do you correct transposition of the great arteries when a baby is born?
They become cyanotic very quickly
- give them drugs to open shunts
- then do operation
What does a hypoplastic left heart cause?
- left ventricle underdeveloped
- ascending aorta is very small
- RV supports systemic circulation via obligatory atrial septal defect and PDA (right to left ductal shunt)
How could you deconstrict the aorta?
Inject prostaglandins
What is pulmonary atresia ?
- pulmonary valve does not form properly
- requires R-L shunt for entire venous return
- blood flow to lungs via patent ductus arteriosus
When does atrial septal defect show symtoms?
Asymptomatic until late into adulthood
-late onset arrythmia & right heart failure
When does ventral septal defect present with symptoms?
Unless small, in infancy with left heart failure.
untreated can lead to inpoerable pulmonary hypertension
