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
100% 90/ No shunts 60 20/8 No pressure gradients75% 75% 100% Normal AV valves Normal semilunar valves 20/ 90/ If this patient was desaturated what would you think?
If you have a hole in the heart whataffects shunt flow?1. Pressure – easy enough to understand2. Resistance – impedance to blood flowRemember, the LV has higher pressure anda 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 shunts Cyanotic CHD (R→L shunts) Obstructive lesions
L→R Shunts (“Acyanotic” CHD) Defects 1. 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 ASD Presents in childhood w/ Presents in infancy w/ murmur or exercise heart failure, murmur, intolerance (AVSD or 1o ASD and poor growth presents earlier) Left heart enlargement Right heart enlargement (LHE) (RHE) Transmits flow and Transmits flow only pressure AVSD can present as either depending on size of ASD & VSD component
Increased PBFLeft Heart Right Heart Overload Overload
Pulm vasc markings equal in upper andlower 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)• “Blue blood bypasses the lungs”• Degree of cyanosis varies• Classify based on pulmonary blood flow (PBF) ↑ PBF ↓ PBF Truncus arteriosus Tetralogy of Fallot Total anomalous pulm. Tricuspid atresia venous return (TAPVR) Ebstein’s anomaly Transposition of the great arteries (TGA)Please note: This is a generalization. In reality most of these defects can present withlow 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% ifThere is unimpeded Equal there is high PBFPBF; thus, extreme pressures pulmonary here too overcirculation.
R→L Shunts ↓ PBF Presents more often with cyanosis See oligemic lung fields Closure of PDA may worsen cyanosisDynamic subvalvular Why are obstruction here causes “Tet spells” pressures equal?
Pulmonary 90% overcirculation Too little 70% PBF70% 99% 60% 99% 99% 99% 70% 60%
Obstructive Lesions Ductal Dependent Non-Ductal Dependent1. Critical PS/AS 1. Mild-moderate AS2. Critical CoA/IAA 2. Mild-moderate CoA3. HLHS 3. Mild-moderate PS Presents in CV shock at Presents in older 2-3 days of age when child w/ murmur, PDA closes exercise intolerance, +/- cyanosis or HTN (in CoA) Needs PGE1 Not cyanotic
Ductal-Dependent Lesion Without a PDA there is no blood flow to the abdomen and lower extremities. (Blue blood is better than no blood.)
Physical Exam Inspection and palpation Cardiac cyanosis must be central Differential cyanosis = R→L PDA shunt Differential edema/congestion implies obstruction of SVC or IVC Increased precordial activity Displaced PMI RV heave = RV hypertension
Physical exam Lungs Respiratoryrate and work of breathing Oxygen saturations Abdominal exam Liver size Extremities Perfusion Edema Clubbing
Physical Exam Pulses (very important) Differentialpulses (weak LE) = CoA Bounding pulse = run-off lesions (L→R PDA shunt, AI, BT shunt) Weak pulse = cardiogenic shock or CoA Pulsus paradoxus is an exaggerated SBP drop with inspiration → tamponade or bad asthma Pulsus 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 Murmurs Systolic Ejection Murmur (SEM) = turbulence across a semilunar valve Holosystolic 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)
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 – organsaffected1. Heart muscle & valves – myocarditis & endocarditis (pericarditis rare w/o the others)2. Joints – polyarthritis3. Brain – Sydenham’s Chorea (“milkmaid’s grip” or better yet, “motor impersistance”)4. Skin – erythema marginatum (serpiginous border) due to vasculitis5. Subcutaneous nodules – non-tender, mobile and on extensor surfaces