Shunts and Obstructions

Question 1

Segmental approach to CHD

Answer 1

Look at segements and their connections

Great veins –> veno-atrial –> atria –> atrial-ventricular –> ventricles –> ventriculo-arterial –> great arteries

Question 2

Most common ASD?

Answer 2

Septum secundum

Question 3

What chambers are the first to dilate in

1. ASD shunt
2. VSD shunt

Answer 3

1. RA and RV

2. LA and LV

Question 4

Acyanotic shunts

Answer 4

Left to right!
ASD
VSD
AVSD
PSA

Question 5

Cyanotic shunts

Answer 5

Right to left!
Eisenmenger syndrome (VSD, AVSD, PDA)
Tetralogy of Fallot

Question 6

Mixed shunt

Answer 6

Cyanotic!

Transposition of the great arteries

Question 7

Degree/direction of shunting depends on which 3 things?

Answer 7

Pressure difference between chambers
Relative compliance between chambers
Size of defect

Question 8

What are some of the sequelae from a left to right shunt?

Answer 8

Pulmonary over circulation
Pulmonary hypertension (stiffening of PAs)
Left sided chamber dilation
Left sided chamber dysfunction
Clinical heart failure
Arrhythmias

Question 9

How does the normal O2 sat change in a VSD? In which places?

Answer 9

In RV and PA the sat increased from 73% to 79% because you are recirculating oxygenated blood

Question 10

What are some sequelae from a PDA?

Answer 10

Same as VSD
Pulmonary over circulation
Pulmonary hypertension (stiffening of PAs)
Left sided chamber dilation
Left sided chamber dysfunction
Clinical heart failure
Arrhythmias

Question 11

How does the normal O2 sat change in a PDA? In which places?

Answer 11

In the pulmonary artery, the sat increases from 73% to 85%

Question 12

Eisenmenger syndrome

Answer 12

When you have left to right shunting that is not detected you get pulmonary over circulation, pulmonary hypertension, becomes severe, and then the pulmonary pressures exceed systemic pressures
When this happens, the shunt reverses from right to left
Become cyanotic

Question 13

The difference between right and left shunting in Eisenmenger vis ToF?

Answer 13

In E, the right to left is because of pulmonary hypertension
In ToF the R to L is because of the obstruction to RV outflow tract - fix this and you’ll be fine because pulmonary circulation is fine

Question 14

How does the normal O2 sat change in ToF? In which places?

Answer 14

RV: decreases from 73 to 69%

LV and Aorta: decrease from 98 to 85%

Question 15

3 ways to survive transposition

Answer 15

VSD, ASD, PDA

This forms a R to L shunt, but at least you get some mixing

Question 16

Where can anatomic obstruction occur?

Answer 16

Supra valvular
Valvular
Sub valvular

Question 17

Implications of an obstruction

Answer 17

No shunts, so oxygenation is normal
But if obstruction is severe, could lead to systemic hypoperfusion which would then result in increased oxygen extraction in the periphery, and low RH oxygen saturations
Major issue is of the pressure gradients across the obstruction, and the effects this has on the chambers

Question 18

Aortic coarctation sequelae

Answer 18

Narrowing/stenosis of the aorta leads to...
Hypertension
Increased LV pressure
Distal hypoperfusion
Progressive LV dilation and dysfunction
Clinical heart failure

Question 19

What clinical findings would you do for coarctations

Answer 19

Measure BP in arms (high)

Measure BP in legs (10-15 mmHg lower)