Congenital Heart Disease (CHD) Principles
Most from faulty embryogenesis during 3-8/40. The most common genetic cause is trisomy 21 (40% have defects esp endocardial cusion), other aneuploides include Turner syndrome, trisomy 13 and 18. Environmental risks include rubella, getational diabetes, teratogens; reduced risk with folate.
Primitive truncus is anterior midline, normally dividing into aorta and pulmonary artery (aorta ant, PA post) with 150 deg counterclockwise rotation > aorta R post, PA L ant. L-TGA is 30 deg clockwise rotation (levo-TGA, aorta L ant). D-TGA 30 deg counterclockwise rotation (dextro-TGA, aorta R ant). DORV 45 deg counterclockwise rotation with aorta on R. Situs inversus 150 deg clockwise rotation (aorta L post).
- Cyanotic (R->L shunt or mixing of blood) or acyanotic
- Pulmonary vascularity
- Increased/congested vascularity
- Plethora – arterial and venous overcirculation. Peripheral vessels > bronchus. Requires pulmonary:systemic circulation of >2:1.
- Pulmonary venous hypertension (passive congestion) – Very rare in children. Enlarged pulmonary vein, indistinct vessels (perivascular interstitial oedema from leak), alveolar odema, effusions.
- Pulmonary arterial hypertension (active congestion) – Not usually congenital heart disease. Enlarged vessels (R desc PA > trachea), extends more peripherally, tortuous, remain distinct.
- Decreased vascularity – Requires pulmonary outflow stenosis and R->L shunt. Oligaemia (radiolucent lungs), thin and wispy vessels.
- Normal vascularity – Uncomplicated valve disease, coartation aorta, mild cardiomyopathy (until CHF develops).
- Asymmetrical flow – in tetralogy of Fallot (reduced on L), persistent truncus arteriosus (low in either lung/lobe), valvular pulmonic stenosis (preferential flow to L PA), obstructive emphysema
- Increased/congested vascularity
- Main pulmonary artery
- Enlarged MPA – increased flow (PDA R->L shunt, pulmonic insufficiency) or poststenotic dilatation (valvular pulmonic stenosis). MPA enlarged and more superior.
- Small/absent MPA – pulmonary outflow obstruction or abnormal position (persistent truncus arteriosus, TGA). Shallow/concave MPA.
- Size – estimated at aortic knob, may indent and displace trachea to the left.
- Small – hypoplasia (hypoplastic LH), some L->R shunts (ASD, VSD)
- Enlarged asc and knob – poststenotic dilatation (AS), increased flow (valve insufficiency, L->R shunt at great vessel level eg PDA, persistent truncus arteriosus; severe tetralogy). If ascending aorta is visualised in children, is always dilated.
- General enlargement – systemic HTN.
- Position – Secondary signs of arch position including position of desceding aorta, tracheal displacement/indentation. R-sided arch isolated, vascular ring (double arch or aberrant L SCA), or occasionally persistent truncus arteriosus, tetralogy of Fallot. Bulge/fullness R paratracheal stripe just above level N L arch, tracheal displacement, desc aorta R of spine.
- Contour – coarctation (figure 3).
- Size – estimated at aortic knob, may indent and displace trachea to the left.
- Cardiac size – subjective, dependent on thymus and inspiration, easier on lat (post heart over vertebra). Specific chamber enlargement dificult in infants. Globular suggests pericardial fluid (viral, rheumatic fever, ARF/CRF, collagen vascular disease, bacteria, rarely TB, fungal, mets; blood from trauma). General enlargement from increased blood volume and elevated cardiac output (renal, high ADH, large AV fistula, chronic anaemia eg sickle cell and thalassaemia, hyperthyroidism).
- Cardiac axis – orientation of apex. Pointing superiorly indicates enlarged RH. Inferior orientation suggests enlarged LH.
- Situs – position of cardiac apex, stomach bubble and liver. If apex and stomach bubble on opposite sides (disconcordance), near 100% incidence of congenital heart disease.
Acyanotic Disease with Plethora
Mostly L->R shunt. Shunts only cause failure after 1/12, as increased pulmonary vascular resistance reduces blood flow through the shunt. Plethora, variable passive congestion (later), cardiomegaly. Hyperinflation common with large shunts ?due to peribronchial oedema. May cause paradoxical emboli.
Persisting shunt may -> pulmonary HTN -> RVH, muscular pulmonary arterial (normally <1mm diameter) media hypertrophy and vasoconstriction, irreversible intimal lesions pulmonary HTN -> increasing RH pressures -> reversed R->L shunt = Eisenmenger physiology.
Ventricular Septal Defect (VSD)
Second most common congenital heart to bicuspid aortic valve. Many are associated with other anomalies (eg TOF), only 20-30% are isolated. Higher risk with FHx (esp mother). Newborns usually asymptomatic. Postnatal pulmonary vascular involution (reduction in PA wall thickeness -> less pulm vasc resistence) -> allows L->R shunt -> murmur and symptoms <2yo. Small defects close spntaneously. Increased pulmonary venous return -> enlarged LV (drooping left border) and LA (bulge upper post border displacing oesophagus and L main bronchus). If large -> biventricular enlargement. Small aorta.
- Perimembranous (80%) – near fusion membranous and muscular portions.
- Muscular (10%) – defects usually small, less haemodynamically significant. May be multiple (‘Swiss-cheese’ septum). 50% of small defects close spontaneously.
- Conus (5%, infundibular, outlet) – below the pulmonary valve
- Posterior (5%, inlet)
Atrial Septal Defect (ASD)
Less common than VSD. LA not enlarged. Enlarged RA, RV. Small aorta. Usually asymptomatic until adulthood. Irreversible pulmonary HTN unusual. Septum secundum is on the R with most of tissue away from the AV region; contains foramen ovale closer to the ventricles. Septum primum is on the L with most of the tissue closer to the AV region; contains ostium secundum is further away from the ventricles than foramen ovale (ostium primum at the AV region closes in utero).
- Secundum ASD (90%) – Deficient or fenestrated foramen ovale defect near centre of septum.
- Primum ASD (5%) – Endocardial cushion defect near AV valves. Common in trisomy 21.
- Sinus venosus defect (5%) – Near entrance of SVC, may be associated with anomalous pulmonary venous return to the RA.
Patent Foramen Ovale (PFO)
Usually closes at birth from increased LA pressures, closes permanently in 80%. In 20% it remains unsealed, opening when pressures are greater on the right eg pulmonary HTN, straining, coughing, sneezing; allowing paroxysmal emboli.
Patent/Persistent Ductus Arteriosus (PDA)
PA -> aorta, normally closes functionally within 24hrs, anatomically within 10days. Delay common in hypoxia, prematurity; cause unknown. 90% are isolated, others may be associated with VSD, coarctation or aorta, pulmonary or aortic valve stenosis. Symptomatic <2yo, mashinery-like murmur. L->R shunt -> enlarged LA, LV, PA, prox aorta, active pulmmonary engorgement.
DDx Aortopulmonary window – rare, incomplete division of primitive truncus arteriosus -> aorta-PA communication just above valves.
DDx Ruptured aneurysm of sinus of Valsalva with fistula between coronary arteries and coronary sinus/PA/R heart.
Atrioventricular Septal Defect (AVSD)
(Atrioventricular canal defect). Failure of the endocardial cushions of AV canal to fuse with malformation of the tricuspid and mitral valves. Common in Down syndrome.
- Partial – Low primum ASD and cleft anterior mitral leaflet (mitral insufficiency). L->R shunt and only mild mitral or tricuspid insufficiency.
- Complete – Large comined AV septal defect with large common atrioventricular ring and five-leaflet valve. All 4 chambers freely communicate with large shunts, usually bidirectional. >1/3 have Down syndrome. Cyanotic, pulm HTN, early CHF. Mitral valve cleft, elongated LVOT (‘gooseneck’ on angio). Marked cardiomegaly (predominantly RA, RV) and pulm vascular engorgement.
(Pulmonary venolobar syndrome, hypogenetic lung sydnrome). Partial anomalous pulmonary venous return (PAPVR) with R PV -> IVC (most common), RA or portal vein, associated with and right lung hypoplasia. In the infant causes CCF, RH overload; in the child recurrent R chest infections; adult asymptomatic. Enlarged vein (scimitar) at right base medially, dextroposition of heart due to hypoplastic R lung. May be associated with absent R PA (lung perfused by aorta), accessory hemidiaphragm, absent IVC, ASD, horseshoe lung, vertebral anomalies.
Acyanotic Disease without Plethora
Essentially congestive heart failure, causes include:
- Anatomic left-sided obstruction:
- Aortic stenosis
- LV dysfunction – anomalous LCA origin, myocarditis, shock myocardium (birth asphyxia), glycogen storage disease, maternal diabetes
- Hypoplastic left heart
- Mitral stenosis
- Cor triatriatum
- Pulmonary venous atresia/stenosis
- Systemic causes:
- High output peripheral AVM (vein of Galen malformation, hepatic haemangioendothelioma)
Congenital Valvular Stenosis
Supra and sub-valvular stenoses not usually associated with poststenotic dilatation.
- Valvular stenosis (most common) – From cusp hypoplasia, dysplasia (thickening, nodular), bicuspid valve or previous rheumatic disease. LV hypertrophy -> rounded L border with inferior pointing of the apex. Calcified aortic valve. Aortic poststenotic dilatation (from jet effect). Ascending aorta should never be seen on normal paediatric CXR, if seen suspect dilatation from AS or aneurysm. Tx long-term antibiotics to prevent endocarditis, risk of sudden death with exertion. If severe there is hypoplasia of the LV and ascending aorta (hypoplastic left heart syndrome).
- Supravalvular stenosis – assoc with William syndrome on chromosome 7 encoding elastin (idiopathic hypercalcaemia of infancy with systemic and pulmonary stenoses, facial dysmorphism, mental and growth retardation, hypercalcaemia).
- Subvalvular stenosis – diaphragm or disporoportionate intraventricular septum hypertrophy.
- Pulmonary valve stenosis – RVH -> retrosternal fullness, upwardly displaced cardiac apex. MPA poststenotic dilatation -> prominent LPA, increased pulmonary vessels on L (preferential flow through stenotic valve, less common than adults). Complete pulmonary valve atresia associated with hypplastic right heart.
- Subvalvular/infundibular pulmonary stenosis usually with tetralogy of Fallot.
- Supravalvular pulmonary stenosis usually multiple stenoses in peripheral PAs.
Congenital Valvular Insufficiency
Isolated insufficiency very rare. Dilation of prox and distal chambers.
Coarctation of the Aorta
May be associated with bicuspid aortic valve (in 50%), ASD, VSD, PDA, mitral stenosis/regurgitation, aortic aneurysm/disection, berry aneurysms of the COW. Ductus arteriosus is distal and opposite to the LSCA.
- Preductal/infantile/diffuse (rare) – Proximal to the ductus arteriosus. From cardiac anomaly reducing blood flow through L heart, and subsequent proximal long segment aortic hypoplasia. If severe lower body circulation dependent on PDA R->L shunt unsaturated blood. Presents earlier in life with early CHF. Seen in 5% of those with Turner syndrome.
- Ductal – Narrowing at the ductus, appearing when the ductus closes ?ductal tissue present in the adjacent aorta
- Post-ductal/adult – Just distal to level of ductus arteriosus. Usually asymptomatic until late unless severe (may be part of more complex anomaly) or L->R shunt. HTN, discrepant UL/LL BP, murmur. LV hypertrophy with rounded/prominent L border otherwise N heart size. Pre- and post-stenotic dilatation -> figure-3 sign. Reverse 3 sign on barium swallow. Occasionally dilatation extends to entire desc T-aorta. Collateral circulation (intercostal aa) with dilatation -> notching inf posterior 3rd-8th ribs, usually not visible until 7-8yo. Tx balloon dilation and stent.
Hypoplastic Left Heart Syndrome
Range of abnormalities causing left sided obstruction including atresia of ascending aorta, atresia aortic/mitral valve ± hypoplastic LA/LV/ascending aorta. PDA dependent. Cardiomegaly, CHF within 1st 2/7 (passive congestion). Tx Norwod procedure (1st stage use of MPA and asc aorta, 2nd stage modified Fontan w RA-PA anastomosis).
Common pulmonary valve incorporated into LA with partial membrane creating an extra chamber (sup-post aspect of LA). Pulmonary venous obstruction with cardiomegaly, passive congestion without LA enlargment.
Bacterial or viral infection, autoimmune, toxic, hereditary neuromuscular. Asymmetric septal hypertrophy may cause subvalvular hypertrophic aortic stenosis. Cardiomegaly (generalised or L-sded), normal vascularity until CHF.
Markedly thickened LV myocardium with elastic and fibrous tissue -> enlarged LV and LA. Enlarged LV causes rounded heart, RV impairment, LLL bronchus compression and atelectasis. CHF.
Cyanotic Disease with Plethora
Mixed oxygenated and deoxygenated blood. TGA, PTA I-III, TAPVR, tricuspid atresia, single ventricle.
Persistent Truncus Arteriosus (PTA)
Aorta and PA from single vessel overriding high VSD. Collett-Edwards classification dependent on site of PA origin: type I MPA from prox truncus; II PAs from post; III PAs from lat; IV from descending aorta. Oval cardiomegaly, plethora (except type IV), dilated aorta/truncus with high arch and elevated LPA. Concavity at usual site of MPA. R arch in 30%.
Total Anomalous Pulmonary Venous Return (TAPVR)
(Total anomalous pulmonary venous connection TAPVC). Pulmonary veins converge into single common vein -> right heart. Communication via ASD or PFO. From atresia of the common pulmonary vein, connected instead to a primitive systemic venous channel. If veins are not obstructed then cardiomegaly with plethora.
- Type 1 (supracardiac) -> supracardiac vein. Typically ‘snowman’/’figure of 8’ configuration (doesn’t develop until later) with enlarged L vertical vein (?persistent L SVC) -> innominate vein -> dilated SVC/azygos, sitting on an enlarged heart. Enlarged RA, RV, RA and pulm vessels.
- Type 2 (cardiac) -> coronary sinus or RA. Enlarged RA, RV and pulm vessels.
- Type 3 (infracardiac) -> oesophageal hiatus -> portal vein or other systemic vein. Isolated or assoc w other cardiac defects. Length and small calibre of common pulm vein increases resistance causing obstruction, causing passive congestion (rather than plethora). No cardiomegaly. DDx hypoplastic L heart, pulmary venous atresia.
Transposition of the Great Arteries (TGA)
- Complete/D-transposition (D-TGA) – most common cyanotic CHD presenting <24h. Ventriculoarterial disconcordance with aorta from RV anterior to PA with ventricles in normal position, separate circulations. Communications via VSD, ASD or PDA with bidirectional shunting. Those with PFO or PDA are unstable shunts which tend to close requiring immediate intervention. In absence of pulmonary stenosis, blood preferentially -> pulm circulation -> overload. CHF in 1st few weeks. Oval cardiomegaly in 1st few days. Narrow superior mediastinum and base of heart (egg on a string) from thymic atrophy, abormal aorta/PA alignment. Most often CXR normal. Active and passive congestion. Retrosternal opacity (anteriorly placed aorta). Tx arterial switch.
- Corrected/L-transposition (L-TGA) – ventricluar inversion accompanying transposed aorta/PA with functional correction. Atrioventricular and ventriculoarterial disconcordance, with morphological RV in position of anatomical LV. RA -> anatomical LV -> PA -> lungs -> LA -> RV -> aorta. Aorta anterior and to the left. Asymptomatic, but poor prognosis if VSD/pulmary stenosis/conduction defect. Prominent left cardiac border (RVOT), left-sided aorta. Variable pulmonary vascularity.
Double-Outlet Right Ventricle (DORV)
Aorta anterior/right of PA arising from RV. PA also originates entirely from RV (type I) or from overriding high VSD hence LV and RV (type II, Taussig-Bing anomaly). Haemodynamics and radiology similar to D-transposition apart from normal or increased cardiac waist (aorta-PA side-to-side). Other complex CHD common.
Group of anomolies with one rudimentary ventricle (usually RV), variable connections. Cardiomegaly and pulm vasc engorgement. With pulmomary valvular stenosis pulmonary flow is reduced, more severe cyanosis.
Cyanotic Disease without Plethora
Obstructed flow through right heart as well as R->L shunt. TOF, PTA IV, tricuspid atresia, TGA, Ebsteins. No/mild cardiomegaly – TOF, pulomonary atresia w VSD. Massive cardiomegaly/RA – Ebstein anomaly, pulmonary atresia w intact septum.
Tetralogy of Fallot (TOF)
Most common cyanotic heart disease beyond the neonatal period. RVOT stenosis (usually infundibular ± valve stenosis causing obstruction), RVH, high (usually large) VSD, with overriding aorta. From embryological anterosuperior displacement of the infundibular septum. Long tortuous ‘wandering’ PDA. May be associated with R arch in 25% with mirror-image branching, tracheo-oesophageal fistula, Down syndrome, scoliosis, coronary anomalies, abnormalities of chromosome 22. PA coarctation, hypoplasia or atresia common. Severe pulmary stenosis -> marked R->L shunt, aorta enlargement, greater overriding, more severe cyanosis. Mild usually acyanotic, assymptomatic (‘pink’/’balanced’ TOF). Reduced pulmonary vascularity with shallow/concave PA, unequal flow may cause PA and lung hypoplasia/atresia (usually L). RVH -> sup-lat displaced apex with normal or mildly enlarged heart size (‘boot-shaped heart’). Pulmonary atresia with VSD is considered the most severe form of TOF, also = truncus arteriosus type IV (large bronchial aa).
Hypoplastic Right Heart
Tricuspid atresia ± pulmonary atresia/stenosis, underdeveloped RV. From unequal division of the AV canal, mtiral valve larger than normal. Isolated RV hypoplasia rare. Small RV. Cardiomegaly, normal or reduced pulm vascularity. Flat/concave PA, enlarged RA. R->L shunt interatrial (ASD, patent foramen ovale) and VSD/PDA. Associated with transposition (PA from LV).
Pulmonary atresia with intact ventricular septum part of hypoplastic RH syndrome. No forward flow from R heart, massive dilatation RA, lesser degree of RV. Marked cyanosis. Requires PDA shunt (prostaglandin E1 to maintain patency prior to surgery).
Rare. Enlarged malformed tricuspid valve with inferior displacement into RV, with atrialisation of part of RV and small remaining RV. Atrialised portion has abnormal muscle contracting poorly -> functional obstruction causing marked enlargement. Atrial R->L shunt through PFO if severe, causing cyanosis. May be asymptomatic to causing RHF. R-sided cardiomegaly, reduced pulmonary vascularity, flattened PA. Prominent RA contour, occasionally bulge superior L cardiac border (small displaced RV) -> squared heart. Small vascular pedicle from small PA.
Rare. Focal or complete absence of RV myocardium, pooly contractility. Similar to Ebstein anomoly.
Cardiac Malpositions and Variants
- Dextroposition – heart shifted to right, from hypoplastic R lung, increased risk of congenital heart disease esp L->R shunts.
- Dextrocardia – apex right of spine from developmental malpositioning.
- Dextroversion – R-sided rotation with RA/RV post and LA/LV anterior. No chamber inversion. Visceral situs solitus or inversus. Frequent congenital heart disease.
- Levocardia – normal position apex L of spine.
- Visceral situs inversus – reversed abdominal situs (L liver, R stomach).
- Situs solitus – normal situs.
- Heterotaxia – abN position of viscera.
(Situs inversus). Most common. Chambers completely inverted, normal AP chamber relationshipts, chamber concordance. Visceral situs inversus. Slight increased risk of congenital heart disease (3-5%). May be associated with Kartagener syndrome (primary ciliary diskinesia) with chornic sinusitis and bronchiectasis.
(Cardiosplenic syndromes, situs ambiguous = no clear left- or right-sidedness). Commonly associated with systemic venous abnormalities, congenital heart disease with RVOT obstruction.
- Asplenia/Ivemark syndrome – ‘bilateral right-sidedness’ with midline liver, asplenia, bilateral three-lobed lung, active pulmonary congestion. Prone to infections by encapsulated bacteria. Associated with complex cyanotic CHD, azygous continuation of IVC, bilat SVC, malrotation, microgastria, midline GB.
- Polysplenia syndrome – ‘bilateral left-sidedness’ with dextrocardia, multiple spleens, bilateral bilobed lungs, midline liver, active pulmonary congestion. Associated with less complex acyanotic CHD incl L->R shunts, ASD, anomalous pulmonary venous return, azygous continuation of IVC, bilateral SVC, malrotation, GB atresia.
Right Aortic Arch
Aorta courses over R main bronchus, descending on R or L of the spine (aorta returns to L just above diaphragm). May form a non-constricting ring or stridor. Branching pattern is mirror image type, or aberrant L SCA (± Kommerell diverticulum). Almost all those with mirror image have cyanotic heart disease, esp TOF. L deviation of oesophagus, trachea, posterior oesophageal indentation if aberrant LSCA.
Double Aortic Arch
Persistence of L and R arches encircling trachea and oesophagus. Dominant R arch with L desc aorta in 75%; dominant L ach with R desc aorta in 20%; equal arches in 5%. Inspiratory stridor worse with feeding. R arch higher than L, anterior and post tracheal indentations, bilateral and posterior oesophageal indentations with R higher than L causing a reverse S pattern. May be associated with TOF, VSD, PDA, co-arctation, TGA, truncus arteriosus.
Anomalous L PA from proximal R PA, passing between trachea and oesophagus. Causes stridor, hypoxia. May compress R main bronchus, long-segment tracheomalacia in 50%, tracheo-oesophageal fistula. Anterior oesophageal indentation (only vascular ring to cause this).
Most asymptomatic, M:F 3:1. Levoposition of heart, focal bulge at level of PA and left atrial appendage, increased retrosternal lucency, lung interposed between heart and L hemidiaphragm.
Surgical Procedures for Congenital Heart Disease
- Fontan – for tricuspid atresia, single ventricle, hypoplastic RV, complex CHD. RA -> PA conduit or anastomosis.
- Glenn – for tricuspid atresia, hypoplastic RV, pulmonary atresia. SVC > R PA anastomosis, bidirectuonal flow supplying both PAs.
- Rastelli – for pulmonary atresia. RV -> PA conduit.
- Intraatrial baffle (Mustard/Senning) – for D-TGA. Atrial rerouting of venous flow.
- Arterial switch (Jatene) – for D-TGA. Switch of aorta nd PA w reanastomoses of coronary aa.
- Norwwod – for hypoplastic LH. 1st stage MPA for asc aorta, enlargement of aortic arch, systemic shunt > distal PA. 2nd stage modified Fontan.
- Blalock-Taussig shunt – palliative for obstructed RVOT/PA (TOF, pulmonary atresia, tricuspid atresia). SCA -> PA graft.
- Closure device – for L->R shunts (ASD, PDA). Percutaneous pluging device across shunt.
- Waterston-Cooley – palliative for obstructed RVOT/PA. Asc aorta > R PA anastomosis.
- Potts – palliative for obstructed RVOT/PA. Desc aorta > R PA anastomosis.
- PA banding – for L->R shunt. Band around MPA.
(Mucocutaneous lymph node syndrome). Inflammatory disease of unknown aetiology. Fever, rash, conjunctivitis, erythema of lips and oral cavity, cervical lymphadenopathy, generalised vasculitis (esp arch and major branches). Acute myocarditis may -> CHF. Coronary aa aneurysms (may calcify) or stenoses.
Esp in tuberous sclerosis. Involute over time.
Other cardiac masses incl angiosarcoma, fibroma, teratoma and haemoangioma (assoc w pericardial effusion).