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
Ductus Arteriosus 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
Ostium Primum defects (10%)
Caudal to the fossa ovalis
Sinus Venosus defects (10%)
Posterior to the fossa ovalis
INSERT FIG 90-1

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
Located between septum secundum and primum
Normally patent prenatally
Allows O2 rich blood from ductus venosus -> 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 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 ASD from other L->R lesions)
Main pulmonary artery enlarged
Eisenmenger syndrome findings
Seen in pulmonary hypertension
Large central pulmonary arteries
Peripheral pulmonary artery tapering
FIG 90-2 triangular cardiac silh FIG 90 -3

20. ASD Imaging – Chest radiography
Mild to moderate cardiomegaly
Increased pulmonary vascularity
No left atrial dilatation
FIG 90-2 triangular cardiac silh FIG 90 -3

21. ASD – Imaging Angiography MRI Cine phase contrast sequences
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
FIG 90 -7

26. AVSD - Anatomy Complete form: Unbalanced AVSD Single AV-valve
Ostium primum 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 Partial 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
Ostium primum 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
FIG

31. AVSD - Imaging Chest Radiography Cardiomegaly Pulmonary plethora
FIG

32. AVSD - imaging Cross sectional imaging Cine phase contrast MRI
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 Long axis ventriculogram
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
90 -11

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
Truncus arteriosus
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
90-12

37. VSD - Anatomy Inlet septum Muscular septum Outlet 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 Small defects
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
Irreversable pulmonary 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 Ductus Arteriosus / 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 2 months
Ligamentum arteriosum 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 inaudable murmer
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

51. PDA Imaging Echocardiography Chest Radiography
Standard imaging technique
PDA size and diameter
L->R Shunt fraction
Degree of pulmonary hypertension
Can identify complicating factors – ductal aneurysm or calcification
Chest Radiography
Premature infants
Pulmonary oedema
Cardiomegaly
+- Associated lung disease

52. PDA Imaging Chest Radiography Term infants
CXR may be normal
Term infants with significant shunting
Cardiomegaly
Increased pulmonary blood flow
Consider PDA in a prem infant with
Increasing granularity of lung fields
Increasing heart size on serial imaging
90-18

53. PDA - Imaging Chest Radiography Prominent ascending aorta and arch
Helps differentiate ASD and VSD from PDA
ASD and VSD have a normal aortic arch
Ductus bump
Prominence of the descending aorta

54. PDA - Imaging Cross sectional Imaging
Reserved for complicated cases to define anatomy
CT / MRI – ductal size and length
Cine phase contrast sequences
Can quantify the amount of flow through the PDA

55. PDA - Imaging Angiocardiography
Reserved for cases where significant pulmonary hypertension is suspected
Assess
Pulmonary vascular resistance
Ductal morphology if transcath
closure planned

56. Aneurysm of the ductus arteriosus (DAA)
1.5 – 8.8% of full term infants
Usually Dx pre-natally or after birth in asymptomatic patients
Possible association with connective tissue disorders
Ehlers-Danlos syndrome

57. DAA - anatomy Saccular or fusiform dilation of the PDA
Etiology unknown
? Intrinsic weakness of wall of the duct
? Delayed closure of aortic side of duct with exposure to systemic pressures

58. DAA - Imaging Chest Radiography Echocardiography MRI/CT or Angiography
Ductal bump in area of main pulmonary artery and aortic arch
Echocardiography
Most oft modality used for Dx
MRI/CT or Angiography
Rarely used to confirm the Dx

59. Aortico-pulmonary Window
Rare – 0.2% CHD
30-50% associated with other abnormalities
VSD
ASD
PDA
Tetralogy of Fallot
Interrupted aortic arch
Aortic coarctation
Subaortic stenosis
Anomalous coronary arteries – pulmonary trunk origin

60. Aortico-pulmonary Window -AnAtomy
Incomplete division of the primitive common arterial trunk
Two distinct semilunar valves
Large oval communication between ascending aorta and pulmonary trunk above the aortic valve

61. Aortico-pulmonary Window –Mori classification
Mori type I
Involves the proximal medial wall of the ascending aorta
Mori type II
Involves the distal posterior wall of the ascending aorta
Mori type III
Involves the medial and posterior walls of the ascending aorta

62. Aortico-pulmonary Window - Physiology
Large high pressure Lt to Rt shunt
Presents in 1st weeks of life
CCF commonly seen
Systolic ejection murmur may be heard
Diastolic murmur – associated pulmonary insufficiency
Bounding pulses frequently encountered

63. Aortico-pulmonary Window - Imaging
Echocardiography
Method of choice
For evaluation of defect anatomy
Relationship to the aortic and pulmonary valves
To define coronary anatomy
Pulmonary pressure and ventricular function
Other defects
Chest Radiography
Mimics PDA on CXR
Cardiomegaly
LA + LV enlargement
Increased pulmonary blood flow
Prominent ascending aorta and pulmonary artery

64. Aortico-pulmonary Window - Imaging
Cross sectional imaging
MRI and CT can depict APW anatomy
Used as adjunct to echo
Shunt volume quantification
Ventricular function evaluation
Angiocardiography
Confirm Dx if echo questioned
Used if pulmonary pressures are needed to be determined
Critical to differentiate from truncus arteriosus (APW has two distinct semilunar valves)

65. Summary Echocardiography MRI / CT CXR Angiography Mainstay
Complicated cases
Also yields good physiological information
CXR
Useful for screening
Angiography
Complicated lesions
Usually used where catheter angio intervention is planned

66. Resources Caffey’s Pediatric Diagnostic Imaging 11th ed – Slovis
Classic Imaging Signs of Congenital Cardiovascular Abnormalities – Ferguson et al - September 2007RadioGraphics, 27, 
Thank you