Paeds cardio

Question 1

Location and function of foramen ovale

Answer 1

Shunt between the atria.
Allows blood in R.atrium to bypass the RV and pulm. circulation.
Becomes fossa ovalis a few weeks after birth.

Question 2

Where do the pulmonary veins drain into?

Answer 2

Carry ox. blood into L atrium

Question 3

What do the pulmonary arteries do?

Answer 3

Carry deoxy. blood from RV to lungs

Question 4

Location and function of ductus arteriosus

Answer 4

Shunt connecting the pulmonary artery with the aorta, bypasses pulm. circulation.
Becomes ligamentum arteriosus when prostaglandins drop.

Question 5

Ductus venosus

Answer 5

Shunt connects the umbilical vein to the inferior vena cava, to bypass the liver.
Becomes ligamentum venosum when cord is clamped.

Question 6

Pathophysiology of patent ductus arteriosus

Answer 6

Pressure in aorta > pulmonary arteries. Get a L to R shunt. Increased pressure in pulmonary arteries causes pulmonary hypertension, R sided strain and RVH.
Greater flow through pulmonary circulation leads to LVH.

Question 7

RF for patent ductus arteriosus

Answer 7

Rubella

Prematurity

Question 8

Sx of PDA

Answer 8

sob
difficulty feeding
poor weight gain
LRTI

Question 9

Murmur heard in PDA

Answer 9

If small, murmur may not be present.

Continuous crescendo-decrescendo machinery murmur, can continue through second heart sound, making it difficult to hear.

Question 10

What investigation should be ordered if PDA is suspected?

Answer 10

Echo

Question 11

PDA prognosis/mx

Answer 11

Small PDAs can be asymptomatic and close spontaneously.

Unless symptomatic, generally monitor with echos until age 1. Beyond 1, it’s unlikely to close spontaneously so will require trans-catheter or surgical closure.

Question 12

Pathophysiology of transposition of great arteries

Answer 12

Attachments of aorta and pulmonary arteries are switched, resulting in two separate circulations that don’t mix. The R side is systemic only. The L side is pulmonary only.

Normal development during pregnancy due to placenta. Following birth, the baby becomes cyanosed and requires a systemic-pulmonary shunt for immediate survival. This shunt may be a PDA, ASD or VSD.

Question 13

How is transposition diagnosed? What arrangements should be made?

Answer 13

Antenatal US.
Requires close monitoring through pregnancy and arranging the birth at a hospital that’s capable of managing the condition.

Question 14

What conditions is transposition associated with?

Answer 14

Coarctation of aorta
VSD
Pulmonary stenosis

Question 15

How does transposition present?

Answer 15

Cyanosis at birth or within a few weeks. A shunt will initially provide some compensation, but within a few weeks baby will develop respiratory distress, tachycardia, poor feeding, poor weight gain, sweating.

Question 16

How is transposition managed?

Answer 16

Definitive management is open heart surgery within a few days using a cardiac bypass machine.

Time can be bought through using a prostaglandin infusion to maintain the DA, or through balloon septostomy.

Question 17

RF for tetralogy of fallot

Answer 17

Rubella

Mum = diabetic/over 40/drinking during pregnancy

Question 18

What are the 4 coexisting pathologies of tetralogy of fallot?

Answer 18

VSD
Overriding aorta (positioned further to the right, more deoxy. enters when the heart contracts)
Pulmonary valve stenosis
RVH

Question 19

Why does RVH occur in tetralogy of fallot?

Answer 19

Increased resistance from p.stenosis and from LV due to VSD.

Question 20

Why does a R to L shunt occur in tetralogy?

Answer 20

Pulmonary stenosis creates greater resistance for RV, so blood is encouraged to flow through the VSD.

Overriding aorta is positioned more to the right, so more deoxy. enters the aorta from the R.

Question 21

What is the impact of the R to L shunt in tetralogy?

Answer 21

Blood bypasses the lungs, travels to the body deoxygenated, causing cyanosis.

Question 22

How is tetralogy diagnosed?

Answer 22

Antenatal scans- echo with doppler flow studies to assess severity of shunt.
Ejection systolic murmur during baby checks.
Can present as heart failure as the child ages.

Question 23

Signs and symptoms of tetralogy of fallot

Answer 23

Cyanosis
Clubbing
Poor feeding
Poor weight gain
Ejection systolic murmur, loudest over pulmonary area.
"Tet spells"

Question 24

Pathology of “Tet spells” in tetralogy

Answer 24

R to L shunt is intermittently, temporarily worsened, precipitating a cyanotic episode. This occurs either when 1) pulmonary resistance increases 2) systemic resistance decreases.

When a child physically exerts itself, more CO2 is produced, which is a vasodilator. Systemic vasodilation reduces systemic resistance, so blood takes the easier path from RV to aorta instead of the lungs.

Question 25

When may “tet spells” occur + how do they present?

Answer 25

Can be precipitated by waking, crying, physical exertion.

Become irritable, cyanosed, reduced consciousness, seizures, potential death.

Question 26

How can tet spells be treated?

Answer 26

Squatting in older kids/knees to chest in younger- increases systemic resistance.

Medical mx: involve senior paed. Think of breathing, increasing resistance and relaxation.

• O2
• Sodium bicarb if met.acid.
• Morphine to reduce resp.drive
• IV fluids to increase preload, more reaches pulm.
• Beta blockers to reduce RV
• Phenylephrine to increase systemic resistance

Question 27

Mx of tetralogy

Answer 27

Definitive mx = open heart surgery.

Prostaglandin infusion can be used to maintain the DA so blood can shunt back from the aorta - pulmonary arteries.

Question 28

Valves on L side of heart

Answer 28

M

A

Question 29

Valves on R side of heart

Answer 29

T

P