Pediatric Cardiology 101

Misty Carlson, M.D.

DISCLAIMER:

This lecture is based on generalizations. In reality, a congenital heart defect (CHD)

can act completely different from one patient to the next (eg- classic ToF vs “pink” ToF).

There are many more CHDs than what I’ve listed and I hope you can use these principles to help you out with those.

Fetal Circulation For the fetus the placenta is the oxygenator

so the lungs do little work RV & LV contribute equally to the systemic

circulation and pump against similar resistance

Shunts are necessary for survival ductus venosus (bypasses liver) foramen ovale (R→L atrial level shunt) ductus arteriosus (R→L arterial level shunt)

Transitional Circulation

With first few breaths lungs expand and serve as the oxygenator (and the placenta is removed from the circuit)

Foramen ovale functionally closes Ductus arteriosus usually closes within

first 1-2 days

Neonatal Circulation

RV pumps to pulmonary circulation and LV pumps to systemic circulation

Pulmonary resistance (PVR) is high; so initially RV pressure ~ LV pressure

By 6 weeks pulmonary resistance drops and LV becomes dominant

Normal Pediatric Circulation

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

No shunts No pressure gradients Normal AV valves Normal semilunar

valves If this patient was

desaturated what would you think?

75% 100%

20/ 90/

20/890/ 60

100%

75%

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

1. Pressure – easy enough to understand

2. Resistance – impedance to blood flow

Remember, the LV has higher pressure and a higher resistive circuit relative to the RV.

Now onto the nitty-gritty …

Congenital Heart Disease (CHD)

Occurs in 0.5-1% of all live births Simple way to classify is:

L→R shuntsCyanotic CHD (R→L shunts)Obstructive lesions

L→R Shunts (“Acyanotic” CHD)

Defects1. VSD

2. PDA

3. ASD

4. AVSD (or complete atrioventricular canal) May not be apparent in neonate due to

high PVR (ie- bidirectional shunt)

L→R Shunts – General Points

PDA & VSD Presents in infancy w/

heart failure, murmur, and poor growth

Left heart enlargement (LHE)

Transmits flow and pressure

ASD Presents in childhood w/

murmur or exercise intolerance (AVSD or 1o ASD presents earlier)

Right heart enlargement (RHE)

Transmits flow only

AVSD can present as either depending on size of ASD & VSD component

Increased PBF

Left Heart Overload

Right Heart Overload

Pulm vasc markings equal in

upper and lower zones

Cardiomegaly

Eisenmenger’s Syndrome

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

Once the PVR gets very high the shunt reverses (ie- now R→L) and the patient becomes cyanotic

R→L Shunts (CCHD)

↑ PBF Truncus arteriosus Total anomalous pulm.

venous return (TAPVR) Transposition of the great

arteries (TGA)

↓ PBF Tetralogy of Fallot Tricuspid atresia Ebstein’s anomaly

• “Blue blood bypasses the lungs”• Degree of cyanosis varies• Classify based on pulmonary blood flow (PBF)

Please note: This is a generalization. In reality most of these defects can present with low or high PBF (eg- ToF with little PS acts more like a VSD with high PBF)

R→L Shunts

↑ PBF Presents more often

with heart failure (except TGA)

Pulmonary congestion worsens as neonatal PVR lowers

Sats can be 93-94% if there is high PBF

Equal pressures here too

There is unimpeded PBF; thus, extreme

pulmonary overcirculation.

R→L Shunts

↓ PBF Presents more often

with cyanosis See oligemic lung

fields Closure of PDA may

worsen cyanosis

Dynamic subvalvular obstruction here

causes “Tet spells”

Why are pressures

equal?

70%

70%

99%

99%

90%

60%

60%

99%

99%

70%

Pulmonary overcirculation Too little

PBF

Different amounts of PBF(Truncus vs ToF)

Obstructive Lesions

Ductal Dependent

1. Critical PS/AS

2. Critical CoA/IAA

3. HLHS Presents in CV shock at

2-3 days of age when PDA closes

+/- cyanosis Needs PGE1

Non-Ductal Dependent1. Mild-moderate AS2. Mild-moderate CoA3. Mild-moderate PS Presents in older

child w/ murmur, exercise intolerance, or HTN (in CoA)

Not cyanotic

Without a PDA there is no blood flow to the abdomen

and lower extremities.

(Blue blood is better than no blood.)

Ductal-DependentLesion

Physical Exam

Inspection and palpationCardiac cyanosis must be central Differential cyanosis = R→L PDA shuntDifferential edema/congestion implies

obstruction of SVC or IVC Increased precordial activityDisplaced PMIRV heave = RV hypertension

Physical exam

Lungs Respiratory rate and work of breathing Oxygen saturations

Abdominal exam Liver size

Extremities Perfusion Edema Clubbing

Physical Exam

Pulses (very important)Differential pulses (weak LE) = CoABounding pulse = run-off lesions (L→R PDA

shunt, AI, BT shunt)Weak pulse = cardiogenic shock or CoAPulsus paradoxus is an exaggerated SBP drop

with inspiration → tamponade or bad asthmaPulsus alternans – altering pulse strength → LV

mechanical dysfunction

Physical Exam Heart sounds

Ejection click = AS or PS Mid-systolic click = MVP Loud S2 = Pulmonary HTN Single S2 = one semilunar valve (truncus),

anterior aorta (TGA), pulmonary HTN Fixed, split S2 = ASD, PS Gallop (S3) – may be due to cardiac

dysfunction/ volume overload Muffled heart sounds and/or a rub = pericardial

effusion ± tamponade

Physical Exam

Types of MurmursSystolic Ejection Murmur (SEM) =

turbulence across a semilunar valveHolosystolic murmur = turbulence begins

with systole (VSD, MR)Continuous murmur = pressure difference

in systole and diastole (PDA, BT shunt)

Innocent murmurs

Peripheral pulmonic stenosis (PPS)Heard in newborns – disappears by one year

of age (often earlier)Soft SEM at ULSB w/ radiation to axilla and

back (often heard best in axilla/back)Need to differentiate b/w PPS and actual

pulmonic stenosis. PS often associated with a valvular click and heard best over precordium

Innocent murmurs

Still’s murmur Classic innocent murmur Heard most commonly in young children (3-5 yrs of

age) but can be heard in all ages “Vibratory” low-frequency murmur often heard along

LSB and apex Positional – increases in intensity when pt is in supine

position Also louder in high output states (i.e. dehydration,

fever) Need to differentate from VSD

Innocent murmurs

Pulmonary flow murmur Often heard in older children and adolscents Soft SEM at ULSB, little radiation; normal second

heart sound Not positional Need to differentiate b/w mild PS and especially an

ASD Hint: ASD would have a fixed split second heart sound

Innocent murmurs

Venous hum Often heard in toddlers, young children Low pitched continuous murmur often heard best in

infraclavicular area, normal heart sounds Positional – diminishes or goes completely away

when pt in supine position or with compression of jugular vein

Need to differentiate between a PDA

Syndrome Associations

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

Hereditary Diseases

Marfan (AD)– aortic root aneurysm ± dissection, MVP, MR, AI

HCM (AD) – outflow tract obstruction, arrhythmias Noonan (AD) – HCM, PS DMD/BMD (X-link) – DCM (>12 y.o.) Williams (AD) – supravalvar AS Tuberous sclerosis – rhabdomyoma Romano-Ward – AD LQTS Jervell & Lange-Nielsen – AR LQTS & deafness

Kawasaki Disease (KD)

Now the #1 cause of acquired heart disease A systemic vasculitis (etiology-unknown) Tests – CBC, CMP, CRP, ESR, EKG, ECHO Rx – IVIG at 2g/kg and high-dose ASA Prognosis – Coronary artery dilatation in

15-25% w/o IVIG and 4% w/ IVIG (if given within 10 days of fever onset). Risk of coronary thrombosis.

Kawasaki – Clinical criteria

Fever for at least 5 days AND 4 of the following 5 criteria:

Eyes - conjunctival injection (ie- no exudate) Lips & mouth - erythema, cracked lips, strawberry

tongue Hands & feet - edema and/or erythema Skin - polymorphous exanthem (ie- any rash) Unilateral, cervical lymphadenopathy

Rheumatic Fever

A post-infectious connective tissue disease Follows GAS pharyngitis by 3 weeks (vs. nephritogenic

strains of GAS) Injury by GAS antibodies cross-reacting with tissue Dx – JONES criteria (major and minor) Tests – Throat Cx, ASO titer, CRP, ESR, EKG, +/-

ECHO Rx – PCN x10 days and high-dose ASA or steroids 2o Prophylaxis – daily po PCN or monthly IM PCN

Rheumatic Fever – organs affected

1. Heart muscle & valves – myocarditis & endocarditis (pericarditis rare w/o the others)

2. Joints – polyarthritis

3. Brain – Sydenham’s Chorea (“milkmaid’s grip” or better yet, “motor impersistance”)

4. Skin – erythema marginatum (serpiginous border) due to vasculitis

5. Subcutaneous nodules – non-tender, mobile and on extensor surfaces

In case you haven’t had enough….

A ductal-dependent lesion

One ventricle pumps both PBF & SBF

Difficult to balance PBF & SBF

Norwood Procedure

What is the purpose of the BT shunt?

Is there a murmur? What is your guess

for the arterial saturation?

Bidirectional Glenn

What is the purpose of the Glenn?

Is there a murmur? What is your guess

for the arterial saturation?

Fontan circuit

What is the path of blood?

Is there a murmur? What is your guess

for the arterial saturation?