peds cardiology

Question 1

embryology

Answer 1

Completion of the third week
Intraembryonic blood vessels noted at day 20
Days 21 – 23: the median heart tube is complete
Day 22: heart starts beating
Days 27 – 29: circulation begins

Question 2

fetal circulation

Answer 2

For the fetus the placenta is the oxygenator so the lungs do no work
RV and LV contribute equally to the systemic circulation and pump against similar resistance (after born RV against less pressure)

Question 3

Shunts are necessary for survival

Answer 3

ductus venosus (oxygenated blood bypasses the liver)
 foramen ovale (R→L atrial level shunt)
 ductus arteriosus (R→L arterial level shunt)

Question 4

In a right to left shunt ??

Answer 4

Blood (that hasn’t traveled to lungs yet) is shunting across to the left side of the heart

The underlying goal of fetal circulation is to get oxygenated blood to the brain of the fetus

Question 5

Fetal Normal Values

Answer 5

Umbilical vein PaO2 is 30-35 mmHg.
Fetus 70-80% saturated at this PaO2
Adult 50-60% saturated at same PaO2

Oxygen delivery must be achieved in a relatively hypoxic environment.

Question 6

residue 143

Answer 6

Single amino acid change histidine to serine

Histidine positively charged. Serine neutral.

This change results in less binding of 2,3 BPG to fetal Hb which increase fetal oxygen affinity

Question 7

transitional circulation

Answer 7

With first few breaths lungs expand and serve as the oxygenator
Placenta is removed from the circuit
Systemic pressure INCREASES (placenta WAS a low pressure circuit, now clamped/removed)
Pulmonary pressure DECREASES
Foramen ovale functionally closes
Ductus arteriosus usually closes within first 2-3 days, due to some residual flow (PGE1,2 KEEPS PDA open : placental makes PGs)
Indomethacin: ENDs PDA

if coarctations, take 7-10 days to close (hypoxic)

Question 8

slide 13: after birth umbilical arteries close

Answer 8

systemic pressure increases–>inc. LA pressure greater than RA, no more right to left shunt

pulmonary pressure decreases, blood goes out to lungs instead of thru PDA

shunts essentially close first 30-45 seconds of life

Question 9

Congenital Heart Disease:

Neonates with CHD often rely on a ?? and/or ?? to sustain life.

Answer 9

patent ductus arteriosus

foramen ovale

Question 10

Unfortunately for these neonates, both of these passages begins to close following birth.
The ductus normally closes by ??
The foramen ovale normally closes by??

Answer 10

72hrs. (so small window to dx!)

3 months.

Question 11

What function does the PDA provide after birth in a baby with cyanotic congential heart disease?
A. Provides a source of pulmonary blood flow
B. Provides a source of systemic blood flow
C. Prevents the PFO from closing
D. Supports blood pressure

Answer 11

Provides a source of pulmonary blood flow

L side pressures are greater, L->R->lungs

Question 12

In the presence of hypoxia or acidosis (present in ductal-dependent lesions), ??

Answer 12

the ductus may remain open for a longer period of time

As a result, these patients can present to the ED as late as the first 2 weeks of life

sepsis should be #1 on ddx but keep ductus open and if find out infectious, close it back up

Question 13

CHD s/s right side (more insidious)

Answer 13

Venous congestion
Hepatomegaly
Ascitis
Pleural effusion
Edema

Question 14

CHD s/s left side

Answer 14

Tachypnea (to breathe off CO2)
Retractions
Crepitations
Pulmonary edema

Question 15

CHD s/s low CO

Answer 15

Acutely:
Pallor
Sweating
Cool extremities
­ capillary refill
Tachycardia

Chronic:
Feeding difficulty (sweating)
Fatigue
Poor growth

present like adult CHF

Question 16

Neonatal Circulation

Answer 16

RV pumps to pulmonary circulation and LV pumps to systemic circulation
Pulmonary resistance (PVR) is high initially; so initially RV pressure ~ LV pressure
By 6 weeks pulmonary resistance drops and LV becomes dominant
(dramatic drop, then slow drop to adult levels)

Question 17

baby comes in hx of ALTE (acute life threatening event)

EKG slide 19

Answer 17

acute life threatening event

LV typically has highest amplitudes (V5, V6)
if V1, V2 higher than V3, V4-6, RVH? right bigger than left? (i.e. Epstein’s??)
no, normal finding: takes time for left side muscle mass to “bulk up”

Question 18

Normal Infant Circulation

Answer 18

LV pressure is 4-5 x RV pressure (this is feasible since RV pumps against lower resistance than LV)
RV is more compliant chamber than LV
LV has stiffer, more muscular wall

Question 19

Normal blood flow values:
No shunts
No pressure gradients
Normal AV valves
Normal semilunar valves

Answer 19

LA: 100%
LV: 90/60
aorta: 100%
RA: 75%
RV: 20/5
pulmonary artery: 75%

Question 20

If you have a hole in the heart what affects shunt flow?

Answer 20

Pressure – blood takes the path of least resistance

Resistance – impedance to blood flow

Question 21

Incidence of CHD

Answer 21

Occurs in 8–10/1000 live births (less than 1%)
Familial recurrence risk:
1 - 3% ⇨ sibling
2 - 4% ⇨ parent
25% ⇨ parent + sibling or 2 parents (Noonan’s syndrome, Turner’s (inseminated))
If the mother has a rare, left-sided defect ⇨ more likely to reoccur in offspring

Question 22

Congenital causes

Answer 22

Multifactorial (70 - 85%) no single/specific cause

Chromosomal (18%)
Down Syndrome: up to 50% will have defects
VACTERL, CHARGE Association: 50 - 85% will have defects

Maternal or environmental (1-2%)

Question 23

Maternal or environmental (1-2%) (is preventable!)

Answer 23

-Illness:
Pre-Gestational Diabetes: 50 % inc. risk (poorly controlled, not gestational DM): risk for VSD, Transposition (TGA), Coarctation (COA)

• Lupus: complete heart block (may do C-section, watch moms w. SLE)
• Infection (Viral): rubella in 1st 7 wks = Patent Ductus Arteriosus
• Substance Abuse: Severe FAS (EtOH) = 50 % have CHD

Question 24

Syndrome Associations

Answer 24

Down – AV canal and VSD
Turner – CoA
Trisomy 13 and 18 – VSD, PDA
Fetal alcohol – L→R shunts, ToF
CHARGE – conotruncal lesions (ToF, truncus arteriousus)

Question 25

Physical Exam

Answer 25

``` Inspection and palpation Cardiac cyanosis is central Differential cyanosis = USMLE PDA with R-->L shunt CoA with PDA after constriction ``` (can't always see cyanosis, check pulse ox) Increased precordial activity Displaced PMI

Question 26

Differential cyanosis

Answer 26

pulse ox on RUE (higher, preductal) and LE, 10% difference in sat before and after coarctation (PDA or coarct. with constricted PDA)

Question 27

pulmonary HTN and PDA causes

Answer 27

"blue blood" (deox) from RV to shunt thru PDA (avoiding lungs) to aorta to systemic circulation

Question 28

if coarctation after PDA constricts

Answer 28

less blood to system, more to pulmonary circulation

Question 29

Physical exam 2

Answer 29

``` Lungs: Respiratory rate and work of breathing Oxygen saturations Abdominal exam: Hepatomegaly Extremities: Perfusion, Edema ``` if blue baby and no breathing problems, heart problem

Question 30

slide 31

Answer 30

diff btw cardiac and pulmonary cyanosis

Question 31

PE: pulses

Answer 31

``` Differential pulses (strong UE, weak LE) = CoA (radial ok, femoral v. weak) Bounding pulse = run-off lesions (L→R PDA shunt, AI, BT shunt) Weak pulse = cardiogenic shock or CoA Any ductal dependent lesion once the PDA is closing ```

Question 32

PE: Heart sounds

Answer 32

Ejection click = AS or PS Loud S2 = Pulmonary HTN Single S2 = one semilunar valve (truncus), anterior aorta (TGA), pulmonary HTN *Fixed split S2 = ASD* Muffled heart sounds and/or a rub = pericardial effusion ± tamponade

Question 33

PE: Types of Murmurs

Answer 33

Systolic Ejection Murmur = turbulence across a semilunar valve (Ao, Pulm) Holosystolic murmur = turbulence begins with systole (VSD, MR) Continuous murmur = pressure difference in systole and diastole (PDA, BT shunt)

Question 34

Simplest way to classify CHD:

Answer 34

L→R shunts – Acyanotic HD R→L shunts – Cyanotic HD -The baby appears cyanotic due to deoxygenated blood entering the systemic circulation Obstructive lesions

Question 35

remember..

Answer 35

pressure dictates flow, blood takes path of least resistance

Question 36

L→R Shunts (“Acyanotic” CHD) May not be apparent in neonate due to ??

Answer 36

``` Defects: VSD PDA ASD AV canal (combined ASD/VSD) - Endocardial cushion defect ``` high Pulmonary Vascular Resistance (PVR) not much pressure difference, not much flow until pulmonary pressures drop

Question 37

PDA and VSD present when ?? | with what??

Answer 37

Presents in infancy w/ heart failure, murmur, and poor growth Left heart enlargement (LHE): Transmits flow and pressure

Question 38

ASD

Answer 38

Presents in childhood w/ murmur or exercise intolerance | Right heart enlargement (RHE): Transmits flow only

Question 39

AV Canal can present as either depending on ?

Answer 39

size of ASD and VSD component

Question 40

both ASD and VSD

Answer 40

increase pulmonary blood flow

Question 41

ASD ?? overload

Answer 41

right heart extra blood from LA LV contracting does NOT transmits pressure to pulmonary circuit, just extra volume -takes longer to present

Question 42

VSD: ?? overload

Answer 42

left heart | LV contracting transmits pressure and volume to pulmonary circuit-->comes back to LV

Question 43

CSR

Answer 43

Pulm vasc markings increased in upper and lower zones | cardiomegaly

Question 44

Is a L--> R shunt a cyanotic lesion?

Answer 44

No but can become one: pulmonary pressures become to great (R-->L) Eisenmenger's syndrome

Question 45

Eisenmenger’s Syndrome

Answer 45

A long standing L→R shunt will eventually cause irreversible pulmonary vascular disease - This occurs sooner in unrepaired VSDs and PDAs (vs an ASD) because of the high pressure transmitted with the VSD/PDA - Once the PVR gets very high the shunt reverses (ie- now R→L) and the patient becomes cyanotic

Question 46

R→L Shunts (cyanotic CHD)

Answer 46

Degree of cyanosis varies depending on the lesion | -Classify based on pulmonary blood flow (PBF)

Question 47

R→L Shunts ↑ PBF | still may be blue

Answer 47

Truncus arteriosus Total anomalous pulm. venous return (TAPVR) Transposition of the great arteries (TGA) Presents more often with heart failure (except TGA) Pulmonary congestion worsens as neonatal PVR lowers (CHF findings) Sats can be 93-94% (high!) when there is high PBF; fetal Hgb, may be pink

Question 48

R→L Shunts ↓ PBF

Answer 48

Tetralogy of Fallot Tricuspid atresia Ebstein’s anomaly Presents more often with cyanosis See oligemic lung fields Closure of PDA may worsen cyanosis (may be PGE dependent)

Question 49

Truncus arteriousus

Answer 49

common trunk, mixing of blue and red blood before entering aorta too much PBF (path of least resistance) may sat 90% (cyanosis: mixed blood reaching system)

Question 50

Tetralogy of Fallot

Answer 50

pulmonary stenosis causes too little PBF-->less oxygenated blood to LV more blue blood from RV and a little red blood from LV to aorta-->system inc. pressure in RV prevents VSD from closing, causes overriding aorta causes RVH may sat 70% (variable) monitor until PDA starts to close, determine if ductal dependent: if yes: PDE then sx

Question 51

truncus on CXR

Answer 51

hazy pulmonary edema lung fields generalized confluence too much PBF

Question 52

ToF on CXR

Answer 52

dark lung fields, decreased vasculature, too little PBF | boot-shaped heart

Question 53

Transposition of the Great Arteries (TGA)

Answer 53

*Most common cyanotic congenital heart defect in newborns* 5% of all CHD, Male to female 3:1 Dextroposition, Parallel circuits Incompatible with life unless communication between the two circuits PDA helps if have restrictive ASD: femoral catheter-->put catheter across ASD, blow up balloon, widens ASD: allows more oxygenated blood flow may sat 75-80%

Question 54

TGA 2

Answer 54

Mixing may occur at a number of levels, most commonly at the atrial level through an ASD or a PFO. -Two levels of mixing are necessary to maintain adequate systemic oxygen delivery with a VSD or PDA serving as an additional site for cardiac mixing. (need equal mixing) In TGA, there can be no fixed shunt in one direction without an equal amount of blood passing in the other direction; otherwise, one circulation would eventually empty into the other.