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Board Prep > Fetal physiology and echo > Flashcards

Fetal physiology and echo Flashcards

1
Q

What % of combined ventricular output does the RV handle vs the LV?

A

RV= ~ 60%, LV ~ 30% aka double

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2
Q

What % of combined ventricular output goes through the pulmonary circulation?

A

7%

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3
Q

What % of combined venticular output goes through the transverse aorta?

A

Just 10%

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4
Q

What is the function of the foramen ovale?

A

To shunt oxygenated blood into the left circulation so it can reach the brain and coronaries

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5
Q

Is the fetal circulation a parallel or in series circulation?

A

Parallel

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6
Q

Umbilical vein:
- Describe anatomy
- Describe normal doppler pattern

A

Vein brings oxygenated blood from the placenta to the fetal circulation (think of how it is in the venous circulation for the baby, but how the oxygenation is different d/t placenta)

Normal doppler pattern is a low velocity, non-pulsatile pattern

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7
Q

Describe abnormal doppler patterns in the umbilical vein

A

Progression from single pulsation to double pulsation (progressive risk of mortality)

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8
Q

Ductus venosus
- Describe anatomy
- Describe the normal doppler pattern

A

Bypasses the hepatic circulation so that oxygenated blood is preserved when entering the heart. Can see on echo via aliasing in the liver.

Normal doppler pattern may have some pulsatility due to sphincter (more so than the UV) but is also mostly continuous, low velocity

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9
Q

Describe abnormal doppler patterns in the ductus venosus

A

1) reduced, absent or reversal of flow
2) abnormalities in velocity and pulsatility index

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10
Q

What is reversal of flow in the ductus venosus doppler associated with?

A

Right sided heart disease such as tricuspid valve abnormalities or pulmonary abnormalities that alter the pressure in the RA

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11
Q

How do you calculate combined ventricular output in a fetal echo?

A

Output across valve = Valve area x fetal HR x VTI
Then add the two outputs together

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12
Q

What physiologic changes may account for gradual increase in combined ventricular output in fetus over time?

A

1) Increased ventricular compliance increasing SV
2) Decreased peripheral vascular resistance decreasing afterload

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13
Q

What is a normal combined ventricular output in a fetus?

A

420-450 ml/kg/min

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14
Q

What disease state can restriction or PFO closure result in?

A

Right heart CHF - ventricular hypertrophy, dilation, tricuspid regurgitation, etc.

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15
Q

Describe the typical doppler pattern through a PFO

A

Right to left, laminar flow

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16
Q

What disease processes can result in reduced or reversal of flow (L->R) through the fetal PFO?

A

Processes that increase left sided pressures, such as MV disease or HLHS or coarctation

17
Q

Describe pulmonary vein doppler patterns

A

Forward flow in systole and diastole, may get some cessation of flow or reversal at atrial systole

18
Q

What disease state can premature closure of the ductus result in?

A

RV pressure overload, hydrops, fetal death

19
Q

What does a normal middle cerebral artery doppler look like?

A

Pulsatile with reduction in velocity during diastole but does not go to zero or reverse

20
Q

What may an increase in peak systolic velocity in the MCA represent?

A

Fetal anemia with increased CO

21
Q

What may blunting of the pulsatility of the MCA via doppler represent?

A

Problems with blood flow to fetus resulting in cerebral vasodilation

22
Q

What may increased pulsatility in the MCA via doppler represent? What would this look like on doppler?

A

Right sided obstruction lesions with ductal run off from the aorta into the pulmonary arteries

Would look like sharp narrow peaks

23
Q

What does a normal umbilical artery doppler look like? What may cause abnormalities?

A

Normal doppler looks alot like aortic doppler with pulsatile antegrade flow during systole and diastole

Abnormalities usually reflective of changes in fetal peripheral resistance or systemic resistance - placental issues

24
Q

Most common indication for fetal echo?

A

Abnormal screening ultrasound by OB (40-50% will actually have disease)

25
Q

Rubella as a TORCH infection is associated with what congenital heart lesion?

A

Pulmonic stenosis

26
Q

When is a fetal echo indicated in a mother with PKU?

A

If the level of phenylalanine is > 10

27
Q

The use of retinoic acid is associated with what CHD?

A

Conotruncal anomalies

28
Q

Most common fetal arrhythmia

A

PACs (best detected through use of spectral doppler)

29
Q

Normal range for fetal cardiothoracic area?

A

25%-35%

30
Q

How is the PR interval measured on fetal echo?

A

Beginning of A wave to the beginning of ventricular ejection

31
Q

Normal fetal cardiac axis

A

30 to 60 degrees (leftward)

32
Q

Fetal teratogens:
- Lithium
- Alcohol
- Indomethacin
- Fetal hydantoin syndrome
- Isoretinion

A

Lithium= Ebsteins (now refuted)
Alcohol = VSD, ASD
Indomethacin= Ductal constriction
Fetal hydantoin syndrome = Coarctation
Isoretinion= Conotruncal, TGA

33
Q

What is most commonly associated with congenital heart block of the fetus?

A

Maternal SSA/SSB antibodies. Will be presented as an M mode with complete dissociation between ventricle and atria

34
Q

How does the incidence of CHD in a fetus of a mother with insulin dependent diabetes compare to the fetus with a 1st degree relative with CHD?

A

Insulin dependent diabetes: 4-10%
First degree relative: 2-4%

35
Q

Most common lesion in a fetus whos mother had insulin dependent diabetes

A

D-TGA > ( TA and TOF)

36
Q

Is maternal warfarin use an indication for fetal echo?

A

No. While teratogenic, not associated with CHD.

37
Q

Twin-twin transfusion syndrome: What are you likely to see in the recipient twin?

A

Polyhydraminos, CHF, acquired RVOT obstruction

38
Q

Twin-twin transfusion syndrome: What are you likely to see in the donor twin?

A

Oligohydraminos, growth restriction, anemia, death

39
Q

Three vessel view: Right vs Left aortic arch

A

Left aortic arch: V sign with trachea outside of V
Right aortic arch: U sign with trachea inside of U

Board Prep (13 decks)

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