Overriding

Dr Paul Brooks MBBS (Hons) FRACP Paediatric & Fetal Cardiologist Western Health & Melbourne Paediatric Melbourne, Australia Overriding aorta

• Objectives

• Improve recognition of lesions with aortic override from screening views through to more advanced fetal echo techniques • Outline of common lesions with aortic override • Basic outline of important factors in counselling and management Overriding aorta

• Relatively diverse group of lesions including abnormalities of the great arterial connections and arrangement • Malaligned perimembranous ventricular septal defect (VSD) • (TOF) • with Ventricular Septal Defect (PAVSD) • Double Outlet Right (DORV) • Truncus Arteriosus (Common arterial trunk) Overriding aorta

• Strong association with extracardiac abnormalities and underlying chromosomal abnormalities Conotruncal lesions

Lesion Incidence % of CHD TOF 26-48 per 100000 4.0-7.0% PAVSD 7 per 100000 ~1.0% DORV 9 per 100000 1.0-1.5% Truncus arteriosus 3 per 100000 0.5%

All complex aortic override* 45-67 per 100000 ~6.9-10.3%

All isolated VSD 150-250 per 100000 23-38% Simple transposition (d-TGA) 20-30 per 100000 3.0-4.5%

* Excluding isolated malaligned perimembranous VSD Screening clues

• Overriding great artery Screening clues

• smaller than aorta Screening clues

• Abnormal relationship of the great arteries Screening clues

• Unfolded aortic arch Screening clues

• Right aortic arch (RAA) Screening clues

• Right aortic arch (RAA)

Note : curved course of the ductus arteriosus Right aortic arch

• Associated structural CHD • Malaligned PMVSD • Tetralogy of Fallot • Pulmonary atresia with VSD • DORV • Truncus arteriosus Right aortic arch Right aortic arch

• Chromosomal abnormalities • RAA with vascular ring • 0-2% 22q11 deletion • RAA isolated mirror image branching • 8% 22q11 deletion • RAA associated with CHD • 24% 22q11 deletion • 22% other (T21, T18, T13, Turner and other)

Razon et al. J Am Soc Echocardiogr. 2014 Berg et al. Ultrasound Obstet Gynecol. 2006 Galindo et al. Prenat Diagn. 2009 Zidere et al. Ultrasound Obstet Gynecol. 2006 4 chamber view

• Importance of direction of scanning on ability to visualize structures VSD; Locations on echo VSD; perimembranous

• Located in upper fibrous region of the septum beneath the septal leaflet of the tricuspid valve adjacent to the aortic valve Anatomical specimens Left ventricular outflow tract Left ventricular outflow tract

• Equivalent of a parasternal long axis view after birth Left ventricular outflow tract

• Equivalent of a parasternal long axis view after birth Short axis views

• Complementary views of the ventricular septum and valves Short axis views Short axis views Short axis views Short axis views Short axis views Short axis views

• Close to a sagittal plane where the aortic and ductal arches are imaged Short axis views

Perimembranous ventricular septal defect Identifying PMVSD

• TOF postnatal image Identifying PMVSD

• TOF postnatal image short axis

Normal Identifying PMVSD

• TOF postnatal image Identifying PMVSD

• Short axis views can clearly identify the VSD Perimembranous VSD Perimembranous VSD Additional cardiac abnormalities Additional cardiac abnormalities Antenatal detection rates, Victoria Australia

Defect N Antenatal Dx N Antenatal Dx (1999-2002) (2009-2011)*

Hypoplastic Left Heart Syndrome 78 66 (84.6%) 31 30 (96.8%) Pulmonary Atresia 32 22 (68.8%) Transposition of the Great Arteries 47 8 (17.0%) 52 32 (61.5%) Tetralogy of Fallot 109 47 (43.1%) 48 26 (54.2%) Truncus Arteriosus 27 18 (66.7%) 8 4 (50.0%) Atrioventricular Septal Defect 71 33 (46.5%) 35 15 (42.9%) 46 12 (26.1%) 41 10 (24.4%)

Total 451 238 (52.8%) 247 139 (56%)

Chew et al. Ultrasound Obstet Gynecol 29(6): 619-624. *Paper in progress. Hutchinson et al. Antenatal Detection Rates British Columbia, Canada: 2 years 01/06/2011-31/05/2013

100 9 0 0 7 90 30 33 24 80 46 44 36 45 70 51 60 78 59 50 100 100 53 100 40 60 29 55 58 36 30 56 % 40 20 18 25 22 10 9 8 20 9 10 7 6 9 0 0 0 0 000 0 4 0 2

% Antenatal Spont Demise % Termination % Antenatal Dx Live born % Postnatal Diagnosis Tetralogy of Fallot

• Spectrum of lesions with • Malaligned VSD • Aortic override • RVOT obstruction (PA generally smaller than aorta) • RV hypertrophy (after birth) Tetralogy of Fallot

• Commonest form of cyanotic CHD • 4-7% of CHD • 26-48/100000 live births Tetralogy of Fallot

• In fetal series • ~30% chromosomal abnormalities • ~30% extracardiac abnormalities • Postnatal series lower incidence of additional findings • Termination of pregnancy • Spontaneous fetal demise • Older studies performed prior to 22q11 deletion testing (8-23% incidence) Tetralogy of Fallot

• Recurrence risk estimates vary • Some studies show higher familial recurrence if parent rather than a sibling 2.5-8% Tetralogy of Fallot

• Need to look carefully at outflow tract (5 chamber view) if that is your only screening image Tetralogy of Fallot

• Need to look carefully at outflow tract (5 chamber view) if that is your only screening image

Note : oblique imaging plane (ribs not horizontal) Tetralogy of Fallot

• Short axis views clearly identify the VSD and anterior deviation of the outlet septum

Normal Tetralogy of Fallot

• Oblique and sagittal views of RVOT can also demonstrate narrowing of the RVOT secondary to anterior deviation of the outlet septum Tetralogy of Fallot

• Associated abnormalities • Pulmonary valve stenosis – majority bicuspid or unicuspid valves • VSD can extend to the inlet septum – more common in T21 • Aortic arch • Right aortic arch ~25% • Aberrant subclavian arteries (right and left) • Left SVC ~11% • Coronary arteries Tetralogy of Fallot - Management

• Depends on degree of pulmonary flow • Adequate pulmonary blood flow • track towards elective complete repair at 6 months • Inadequate pulmonary blood flow • deliver in tertiary centre • shunt as initial palliative procedure Tetralogy of Fallot - Management

• Third trimester scans important to evaluate for retrograde flow in the duct Tetralogy of Fallot

• Mortality outlook • Excellent operative mortality 1.0-2.6% • 4/434 TOF repairs. Toronto, Canada 2000-2012 • Hickey et al. Ann Thorac Surg. 2018 Sep;106(3):822-829 • 5/177 repairs. Rotterdam, Netherlands 2000-2015 • Mouws et al. Semin Thorac Cardiovasc Surg. 2018 Nov 2 • Long term mortality outlook • US Pediatric Cardiac Care Consortium 1982-2003 • 3283 patients surviving repair surgery • 25 year survival 94.5% • Smith et al. JAMA Cardiol. 2019 Jan 1;4(1):34-41 Pulmonary atresia with ventricular septal defect (PAVSD)

• Rare approximately 7/100,000 live births • ~1% of CHD • Extreme end of spectrum of Tetralogy of Fallot • ~30% chromosomal abnormalities • ~30% extracardiac abnormalities • Right aortic arch in 25-50% PAVSD

• 3 main options for pulmonary arterial supply • Via a ductus arteriosus (~80%) • Multi focal supply via collateral arteries which connect to confluent central pulmonary arteries (~8%) • Multi focal supply with no true central pulmonary arteries (~12%) PAVSD

Vesel et al. Heart. 2006;92:1501-05 PAVSD PAVSD PAVSD PAVSD with MAPCA’s

• Retrograde filling of the pulmonary circulation from multiple collateral arteries not the ductus arteriosus • Identifying confluent central pulmonary arteries has important prognostic implications PAVSD with MAPCA’s PAVSD with MAPCA’s Unfolded aortic arch • TOF • PAVSD • Truncus • DORV • TGA PAVSD with MAPCA’s PAVSD with MAPCA’s PAVSD with MAPCA’s PAVSD with MAPCA’s Management

• Delivery in a tertiary centre • Prostaglandin E1 (PGE1) infusion at delivery • Aim to complete a biventricular circulation • Shunt as early palliation if duct dependent circulation • Complete repair with RV to PA conduit and VSD closure • PAVSD MAPCA’s • May not need shunt if adequate pulmonary blood flow • Natural history of collateral arteries is to develop stenosis even if large early in life Shunt surgery

Complete repair surgeries with RV to PA conduit

+/- children with MAPCA’s

Unifocalization of MAPCA’s

PAVSD Outcomes

• Those able to achieve complete repair do better although long term outlook is not as favourable as TOF • Complete repair • 75% survival at 22 years • Palliative or staged surgery not reaching complete repair • 61% survival at 22 years

Cho et al. J Thorac Cardiovasc Surg 2002;124:70-81 Double Outlet Right Ventricle

• Rare ~ 9/100000 live births • 1.0-1.5% of CHD

• In simple terms >50% override into the RV the most practical way to identify DORV antenatally Double Outlet Right Ventricle

• Type depends on relationship of the great arteries and position of the VSD • DORV with sub-aortic VSD (Tetralogy of Fallot type) ~68% • DORV with sub-pulmonary VSD (Transposition type or Taussig-Bing Anomaly) ~22% • DORV with doubly-committed VSD ~3% • DORV with non-committed VSD ~7% Double Outlet Right Ventricle

• DORV sub-aortic VSD (TOF type) largely managed the same way as Tetralogy of Fallot Double Outlet Right Ventricle

• DORV sub-aortic VSD (TOF type) • Same risks of associated chromosomal abnormalities and extracardiac pathology Double Outlet Right Ventricle

• DORV sub-pulmonary VSD (TGA type) • Can have smaller or larger aorta • More often associated with complex CHD

Smaller PA in this example Double Outlet Right Ventricle

• Associated abnormalities • Pulmonary stenosis ~70% • Secundum ASD • Left SVC • LV outflow tract restriction due to a small VSD • Sub-aortic stenosis and arch pathology (Taussig-Bing anomaly) • Mitral valve abnormalities and LV hypoplasia • Right isomerism, often also associated with an unbalanced AVSD Double Outlet Right Ventricle

• Outcomes • Varying and dependent on anatomical complexity • RCH Melbourne 1978-2007 cohort of 352 patients • Sub-aortic VSD (TOF type) 4.2% mortality • Sub-pulmonary VSD (TGA type) 11.4% mortality • Doubly committed VSD 20% mortality • Non-committed VSD 15% mortality • Associated AVSD 28.3% mortality

Paediatric Cardiology 3rd Edition. Churchill Livingstone 2010 Truncus arteriosus

• Common arterial trunk giving rise to both aorta and pulmonary arteries

• Rare ~ 3/100000 live births • ~0.5% of CHD Truncus arteriosus

• Be careful of still images or non-representative clips which can give false reassurance of normality Truncus arteriosus

• ~60% chromosomal abnormalities • ~50% extracardiac abnormalities

• Only 15% isolated CHD Truncus arteriosus

• Arterial valve regurgitation in a large overriding great artery may be the clue that it is a common arterial trunk Truncus arteriosus Truncus arteriosus

• Identifying subtypes of how the pulmonary arteries arise from the aorta is not always easy and does not significantly alter counselling – with one exception Truncus arteriosus

• Identifying subtypes of how the pulmonary arteries arise from the aorta is not always easy and does not significantly alter counselling – with one exception

• Associated interrupted aortic arch (~10%) Truncus arteriosus

• It is not always easy to clarify from where the pulmonary arteries arise Truncus arteriosus

• Long term outcomes surgery • RCH Melbourne 1979-2014 • 171 patients • 20/171 early mortality 11.7% • 73.6% survival at 30 years • Re-operation rate 96% at 20 years • 34 patients required truncal valve repair or replacement at initial or late surgery • Risk factors for mortality • Post operative ECMO • Coronary abnormalities • Weight <2.5kg

Naimo et al. Semin Thorac Cardiovasc Surg. 2016;28(2):500-511 Summary

• An overriding aorta is not always immediately obvious • Careful assessment of standard screening views with the addition of color Doppler will identify the majority of lesions with aortic override • Up to 10% of structural CHD lesions are associated with aortic override Summary

• Associated chromosomal and extracardiac abnormalities are common and impact on morbidity and mortality • Fetal echocardiography helps refine perinatal management which depends on the degree of pulmonary blood flow • Surgical outlook varies in lesions with aortic override from simple VSD closure, to complex and repeated multistage surgery throughout life