Congenital Heart Disease with Left to Right Shunt

1. Congenital Heart Disease with Left to Right Shunt Michael Pieters Dept. of Diagnostic Radiology Bloemfontein

2. Overview • Classification of congenital heart lesions • Factors that influence lesion presentation • Imaging chain sequence • Left to right Shunt lesions • Anatomy • Physiology • Imaging

3. Classification of Congenital Cardiac Lesions • Shunt lesions • Right heart lesions • Left heart lesions • Abnormal origin of the great arteries

4. Factors that influence lesion presentation • Age of child • Severity of the lesion • Example – VSD • R to L shunt at birth • L to R shunt with CCF as age increases • The anatomy of the lesion remains constant • Radiographic features and clinical findings change with time • Classic radiographic features of certain lesions – rarely seen

5. Imaging chain sequence • The imaging sequence varies with • Age • Clinical presentation • Type of lesion • Echocardiography • Chest Radiography • CT • MRI • Angiography

6. Congenital Cardiac Left to Right Shunt Lesions • ASD • VSD • PDA • DuctusArteriosus Aneurysm • Aortico-Pulmonary Window

7. Cardiomegaly • Cardiomegaly on CXR • Asses pulmonary vascularity - ? Increased • Read history - ? Acyanotic patient • Ddx: • ASD • AVSD • VSD • PDA • Aortico-pulmonary window

8. ASD • 10% of all CHD • Incidence - twice as common in females • Secundum defects – likely genetic cause • Holt Oram • Familial ASD

9. ASD Anatomy • 3 Primary types • Relationship to the fossa ovalis • Secundum defects (80%) • Region of fossa ovalis • OstiumPrimum defects (10%) • Caudal to the fossa ovalis • Sinus Venosus defects (10%) • Posterior to the fossa ovalis

10. ASD – sinus venosus defects • Not true ASD’s • Defect in the septum which separates the • sinus venosus portion of the RA from the • right pulmonary veins and systemic veins • Most often found in the wall between the • Posterior inferior border of SVC and • RA • Commonly assosciated with anomalous connection of • Right upper, middle or lower pulmonary veins draining to the • RA or SVC

11. ASD – sinus venosus defects • Much less commonly - defect is found in the wall between the • Inferior RA at its junction with the • IVC • Assosciated with anomalous connection of • Right middle or lower pulmonary veins • draining to the RA or SVC

12. ASD – Coronary sinus septal defects • Rare spectrum of lesions • Partial or complete absence of wall between • Coronary sinus and LA • Associated with a left SVC draining to the coronary sinus • Blood shunts from the LA to the RA via “unroofed” coronary sinus

13. ASD – Patent Foramen Ovale • Foramen Ovale • Located between septum secundum and primum • Normally patent prenatally • Allows O2 rich blood fromductusvenosus-> reach LA • Sealed after birth • Increased LA pressure vs RA • Probe patency • 25% of adults • Functionally closed • Right to left shunt possible - Valsalva

14. ASD – Common atrium • Atrial septum completely absent • Common in visceral heterotaxy syndromes

15. ASD - Physiology • Left to right shunt volume determined by • ASD size • Left heart compliance • Pulmonary vascular resistance • Large defects show increased size of • RA • RV • Pulmonary artery • Right to left shunt will occur when • Pulmonary vascular resistance > Systemic vascular resistance

16. ASD – clinical presentaton • Detected 1-2 yr of age • May present earlier @ 6-8 weeks with murmur • Older children with large ASD • Fatigue and dyspnoea • Split second heart sound – no variation with respiration • Diastolic flow murmur • Adults – flow related pulmonary arterial hypertension

17. ASD Imaging - Echocardiography • Modality of choice for Dx • Localising • Size • Shunt direction and severity (Colour Doppler) • Right ventricular qualitative function • Septal bowing (Rt to Lt) • Points to volume overload

18. ASD Imaging - Echocardiography • Right ventricular pressure • Assessed by evaluating the degree of: • Tricuspid regurgitation • Septal systolic position (systolic septal flattening – increased RV pressure) • PFO • Dx – flap valve or • Saline injection to right heart + Valsalva • Rt to Lt shunt on Valsalva • TEE

19. ASD Imaging – Chest radiography • Neonate • Normal cardiac size • Normal pulmonary flow • Later infancy and childhood • Mild cardiomegaly • Triangular cardiac silhouette • Left atrium normal • distinguishes uncomplicated ASDfrom other L->R lesions) • Main pulmonary artery enlarged • Eisenmengersyndrome findings • Seen in pulmonary hypertension • Large central pulmonary arteries • Peripheral pulmonary artery tapering

20. ASD Imaging – Chest radiography • Mild to moderate cardiomegaly • Increased pulmonary vascularity • No left atrial dilatation

21. ASD – Imaging • Angiography • Asses haemodynamic consequences of ASD or • Used if transcatheter closure is planned • MRI • Adjunct to echo • >90% sensitive and specific for ASD localization and detection • Useful in pt with poor acoustic windows • Can lead to ASD being misdiagnosed • atrial septum is thin on BW images – rather use MRI cine • GE and steady state free precession cine – shows turbulent jet over ASD • Cine phase contrast sequences • Show direction and amount of shunting

22. ASD – MRI Dynamic perfusion study • PFO can be demonstated by injecting Gadolinium into the right heart + Valsalva • ASD haemodynamic evaluation • Demonstrates Eisenmenger syndrome physiology • Contrast seen crossing the atrial septum from the RA to the LA

23. AVSD • 2-5% of all CHD • 40% of Down’s syndrome patients have CHD • 40% of Down’s pt with CHD have AVSD • Associated with visceral heterotaxia / asplenia and polysplenia syndromes • Ellis van Creveld syndrome

24. AVSD • Lesions associated with AVSD • PDA (10%) • Tetralogy of Fallot (6%) • Transposition of the great arteries • Double outlet RV • Aortic coarctation

25. AVSD - Anatomy • Abnormal development of the endocardial cushions • Mild form - partial AVSD: • Crescent shaped defect in the inferior portion of the atrial septum adjacent to the AV – valves • Cleft mitral valve • Separate mitral and tricuspid valve orifices

26. AVSD - Anatomy • Complete form: • Single AV-valve • Ostiumprimum ASD just superior to the plane of the AV – valve • Large VSD beneath the plane of the AV - valve • Cleft in the anterior leaflet of the mitral valve • Cleft in septal leaflet of tricuspid valve • The common AV-valve has 5 leaflets • Shortened left ventricle inlet • Left ventricle papillary muscle defects • abnormally close to each other or • only one papillary muscle • Unbalanced AVSD • Relative hypoplasia of one of the ventricles

27. AVSD - physiology • Complete AVSD • Left to right shunt - related to size of defect and pulmonary vascular resistance • Shunting may be interatrial or interventricular • Cleft Mitral Valve leads to mitral regurgitation and CCF • Pulmonary hypertension develops (more common in Down’s pts)

28. AVSD presentation • Infants with complete AVSD • Tachypnoea, tachycardia • CCF sx when pulmonary resistance starts to fall • Signs and symptoms vary according to the degree of shunting • Partial AVSD • Infants usually asymptomatic • Can present earlier if severe mitral incompetence

29. AVSD - Imaging • Echocardiography • Accurately demonstrates AVSD components • Ostiumprimum defect • Inlet portion of the ventricle • Abnormal valve leaflet morphology • Papillary muscle architechture • Shunt level and flow direction • Ventricular function and size • Evaluate for outflow tract obstruction • Pulmonary and systemic venous anatomy (must be documented because of frequency of associated heterotaxy abnormalities)

30. AVSD - Imaging • Chest Radiography • Moderate to marked cardiomegaly • RV and RA enlargement (more in complete AVSD) • Increased pulmonary vascularity • Left atrial enlargement – if associated mitral incompetence • Lung infiltrates (increased pulmonary blood flow associated with recurrent LRTI) • Lung hyperinflation – seen with large left to right shunts • due to increased blood volume with increased overall lung volume as well as increased airway resistance from enlarged arteries and veins

31. AVSD - Imaging • Chest Radiography • Cardiomegaly • Pulmonary plethora

32. AVSD - imaging • Cross sectional imaging • Not needed in initial Dx • Used to confirm Dx and • evaluate the size and morphology of the atria, leaflets, ventricles and great vessels • Evaluate ventricular function • Cine phase contrast MRI • Assessment of shunt fraction (Qp/Qs) • Valvular function

33. AVSD - Imaging • Angiocardiography • Rarely necessary for Dx • Used if Dx is unclear or haemodynamic information is needed • Long axis ventriculogram • Goose neck deformity of left ventricular outflow tract • Anterior superiorly positioned aortic valve • Elongated and narrowed LV outflow tract

34. VSD • 20% of all CHD • 2/1000 Live briths • VSD + complex CHD account for > 50% of CHD • Most common lesion in trisomy 13,18 and 21 • Incidence slightly higher in females • Incidence varies on age of evaluation • Most small VSDs close spontaneously

35. VSD • Isolated or • as part of complex CHD • Tetralogy of Fallot • Truncusarteriosus • ASD • Coarctation of the aorta • Tricuspid atresia • Transposition of the great arteries • Double outlet RV

36. VSD - Anatomy • 4 Components of the ventricular septum • Inlet septum • Muscular septum • Outlet septum • Membranous septum • VSD involves one or more component

37. VSD - Anatomy • Inlet septum • Contains AV valves and their attachments • Formed from endocardial cushions • AVSD defect location • Muscular septum • Trabeculated portion of RV (viewed from RV) • From tricuspid valve leaflets to RV apex and crista supraventricularis • Location of single or multiple muscular defects • Outlet septum • Extends from the crista supraventricularis to pulmonary valve (viewed from RV) • Membranous septum • Inferior to the right and non-coronary cusps of the aortic valve • 80% of VSDs involve this area

38. VSD - Physiology • Physiologic effect determined by • VSD size • Rt and Lt heart compiance • Pulmonary vascular resistance • Small defects • High flow resistance • Large defects • Low flow resistance • High blood flow in the pulmonary vasculature • Leads to pulmonary vascular obstructive disease

39. VSD - Symptoms • Symptoms dictated by • VSD size • Degree of Left to Right shunt • Typical signs in > 1 month of age • PSM as pulmonary resistance falls • No murmur in large VSD • Loud split 2nd heart sound • Significant shunt • Failure to thrive • Dyspnoea • CCF • Irreversablepulmonary vascular obstructive disease • Shunt reversal

40. VSD - Imaging • Echocardiography • Method of choice • Used to asses the location, number and size of VSDs • Shunt assessment • Colour Doppler is useful to identify muscular VSDs • RV + Pulmonary artery pressures measured • Rt + Lt heart volumes are measured • Tricuspid and Aortic valves • Assessed for possible tethering of the valve tissue into the defect borders • TEE used if poor acoustic windows

41. VSD - Imaging • Chest Radiography • Findings depend on VSD size • Small VSD – may have normal CXR • Moderate to large VSD • Cardiomegaly with LA, LV, RV enlargement • Enlarged pulmonary arteries • Increased pulmonary blood flow • CCF frequent in infants + large defects • Older children – pulmonary hypertension likely • Large central pulmonary arteries • Pruned peripheral pulmonary arterial branches

42. VSD – Cross sectional imaging • Echocardiography usually sufficient • Muscular VSDs sometimes detected on routine CT Chest • MRI • 90% accuracy in VSD detection • Larger defects seen with • Spin Echo or • Double inversion recovery techniques • Smaller defects seen with • GE or • Steady state free precession images

43. VSD – Cross sectional imaging • MRI • Shunt evaluation • Cine phase contrast measurements in aorta and pulmonary artery • Rt + Lt Ventricular stroke volume comparison • Quantative assessment • Rt and Lt ventricular function • Rt and Lt ventricular volumes • Ejection fractions • Evaluation for extracardiac vascular anomalies

44. VSD - Imaging • Angiocardiography • Used to • Assess pulmonary vascular resistance • Quantify intracardiac shunting • Evaluate for ventricular septal defect anatomy • Evaluate the coronary arteries • Evaluate for associated valvular and vascular anomalies • Angiocardiography used if echocardiographic evaluation was insufficient or if transcatheter VSD closure is planned

45. PDA • 5-10% of CHD • 1/1600 live births • Twice as common in females • 20-30% of prems have PDA • Often associated with • VSD • Aortic coarctation • Aortic stenosis • Mitral regurgitation

46. PDA - Anatomy • Persistence of embryologic 6th aortic arch • 6th Aortic arch connects Lt pulmonary artery with descending aorta • PDA may be on the right with a Rt arch

47. PDA - Anatomy • DuctusArteriosus / Aorta angle • Acute angle seen in isolated PDA with pulmonary atresia • Ductal dependant pulmonary flow • Obtuse angle seen in Non-ductal dependant pulmonary flow

48. PDA –prostaglandins and O2 • PG keep the duct patent during foetal life • At birth blood [O2] rises and [PG] lowers • Functional ductal constriction • Complete closure @ 2 months • Ligamentumarteriosum remains (may calcify) • In Premature infants closure is delayed due to • Less sensitive ductal tissue to [O2] • Respiratory distress – hypoxia -> increased [PG] • In full term infants • Rubella • Asphyxia • Genetic and environmental causes

49. PDA - Physiology • Amount of Lt to Rt shunt dictated by • Ductal length and diameter • Degree of pulmonary hypertension • Untreated PDA leads to Pulmonary vascular obstructive disease • Prem with no significant lung disease • Systolic high frequency murmur • CCF (large shunt) • Prem with significant lung disease • PDA prevalence > 80% • Almost inaudablemurmer • Dx with echocardiography

50. PDA - Physiology • Term infant with small PDA • Usually asymptomatic • Murmur present • Infant with moderate to large PDA • Continuous machinary like murmur • FTT • Poor feeding • CCF • Irritability