1. Fetal Chest and Heart Notes from S.Khangure and A.Law
Edited by A.Bartley

2. Normal Imaging of the Chest
Heart:
¼ to 1/3 of thoracic cavity
Apex to left
Cardiac axis approximately 45°
Lungs
Homogenous, intermediate echogenicity
Echogenicity increases with age
Volume of right greater than left, lobar anatomy not appreciable
Diaphragm
Continuous hypoechoic band between pleural and peritoneal cavities

3. Fetal Heart

4. Normal Lungs and Diaphragm

7. CONGENITAL DIAPHRAGM HERNIA Bochdalek - 90% on left; most unilat
All should have amniocentesis and dedicated echo
Secondary pulmonary hypoplasia is major cause of mortality
Findings
Polyhydramnios
Stomach/bowel/liver adjacent to heart
Absent stomach bubble in normal spot
Peristalsis in chest
Mediastinal shift
Absent gastric bubble
Reduced abdominal circumference compared to rest of fetal biometry

8. Associated anomalies DDX
Aneuploidy (T18, T21); NTD; CHD; malrotation, omphalocele
DDX
CCAM
Other cystic masses such as foregut duplication cysts are rare

10. Most common fetal lung mass (75%) Types I-III
CCAM
Most common fetal lung mass (75%)
Types I-III
Types I and II macroscopic cysts >5mm with good prognosis and hydrops is rare
Small risk of malignant degeneration (rhabdomyosarcoma)
Imaging
Macroscopic types appear cystic
Microscopic types appear solid (echogenic)
Pulmonary hypoplasia of normal lung - degree determines prognosis
Mediastinal shift - cardiac compromise causes polyhydramnios (impaired swallowing) and hydrops
Associations (type II)
Cardiac anomalies
Pulmonary sequestration
Pectus excavatum
Jejunal atresia
Renal agenesis, prune-belly syndrome
Pathology
Hamartomatous proliferation of terminal bronchioles
Cysts lined by respiratory epithelium and communicate with airways at birth
Vasc supply from pulmonary artery

11. CCAM

13. EXTRALOBAR SEQUESTRATION
More common in males (4:1)
90% LLL or below diaphragm
Always airless as it has its own pleural envelope and no communication with bronchial tree
Systemic arterial supply - Aorta 80%
Systemic venous drainage - IVC, azygos, portal v
Imaging Findings
Solid hyperechogenic mass
Look for systemic arterial supply on Doppler
Polyhydramnios
Hydrops
Associations 65%
CDH
Cardiac
GI, Renal, Vertebral anomalies
Often regress in utero
DDX
CCAM
Congential lobar emphysema (initially filled with fetal fluid)
Neuroblastoma
Other arterial supply - splenic, L gastric, SCA, intercostal arteries

14. Bronchopulmonary Sequestration

15. Teratoma Neoplasm composed of all three germ cell layers
In the thorax, most originate from the mediastinum or pericardium, primary lung teratomas are rare
Variable size but typically large, may grow rapidly
Appears as heterogenous mass with solid and cystic components, calcification is the most specific feature but is not always present, no feeder vessel
Mediastinal
Typically occur anteriorly and may cross midline
Difficult to distinguish from lung mass
Pericardial
May be intra or extra pericardial. Intracardiac nearly always have a pericardial effusion and are at risk of tamponade

16. Pericardial Mass

17. Hypoplasia – decrease in number and size of airways and alveoli
PULMONARY HYPOPLASIA
Agenesis – complete absence of one or both lungs (airways, alveoli, and vessels)
Aplasia – absence of lung except for a rudimentary bronchus that ends in a blind pouch
Hypoplasia – decrease in number and size of airways and alveoli
Primary
Secondary
Bilateral - Oligohydramnios (Potter’s sequence); Skeletal dysplasia
Unilateral - CCAM; Sequestration; CDH; Hydrothorax
Imaging
Reduced thoracic circumference (<2SD) is suggestive
Fetal lung maturity best sssessed with lecithin:sphingomyelin ratio in amniotic fluid
Echogenic pattern unreliable marker for maturity

18. Pulmonary Hypoplasia Oligohydramnios Cardiac Malformations
Renal conditions (agenesis, obstruction, polycystic disease)
PROM
IUGR (placental insufficiency, aneuploidy)
Cardiac Malformations
Right sided obstruction decreasing pulmonary blood flow
Pulmonary atresia or stenosis
Hypoplastic right heart
Neuromuscular Abnormalities
Decreased fetal breathing and poor lung development
Thoracic cavity mechanical problems
Small or deformed thoracic cavity – osteogenesis imperfecta, achondrogenesis, asphyxiating thoracic dystrophy etc.

19. Pulmonary Hypoplasia Imaging
No universally accepted diagnostic criteria
Many measurements and ratios
Thoracic circumference – correlate with GA or as ratio with another growth parameter, particularly AC. TC/AC ratio > 0.80
Lung head ratio – mainly in CDH – measure contralateral lung volume and divide by HC to give LHR - <1.0 poor, >1.4 good
Peripheral pulmonary artery resistance (Doppler) – increased in hypoplasia but non specific
Pulmonary artery Doppler of acceleration time/ejection time (AT/ET).
Normal ‘spike and dome’ pattern with reversal of flow at diastole due to closure of pulmonary valve
Normal ratios are 0.17 on right, 0.15 left, low ratio suggestive of hypoplasia

20. Normal Pulmonary Artery

21. Fetal Heart Normal View
4 chamber view
Atrial and ventricular septa, mitral and tricuspid valves
Axis 45°-50°
Foramen ovale interrupts atrial septum, with the flap of the foramen opening towards the left atrium
Ventricles are approximately same size
Right ventricle characterised by moderator band, and lower septal attachments of tricuspid valve
Base of heart
Left and Right ventricular outflow tracts
Aortic ‘candy cane’
4c, lvot, rvot, arch, darch

22. FETAL HEART Technique Abdominal situs view
4-chamber view
LVOT
Posterior/central to RVOT
Runs left to right
RVOT
Anterior to LVOT
Runs right to left
Bifurcates early: DA and RPA
Check for antegrade flow in DA
Anatomical trifurcation: DA, RPA, LPA
3-vessel view
amniocentesis indicated in all abnormal: 15-40% will have chromosomal anomalies
ventricles/atria are of roughly same size as other ventricle/atria
3 in 1 rule: heart fills 1/3 of axial chest
Cardiac circumference 1/2 chest circumference
Length atrial septum: ventricular septum 1:2
Normal HR: bpm, SR

23. Best seen on Four-Chamber View
Septal defect
Endocardial cushion defect (AVSD)
Hypoplastic left heart
Ebstein’s anomaly
Critical AS
Coarctation

24. 4 chamber view

25. 3-VESSEL VIEW

26. Base of Heart

27. Base of Heart

28. VOT

29. Aorta – candy cane

31. Pericardial Effusion Pericardial fluid >2mm in depth is abnormal
Multiple causes:
Cardiac abnormality
Structural
CMO
Arrhythmia
As a feature of hydrops
Congenital infection – TORCH
High output state
tumour
AVM
anaemia
TTTS

32. VSD
Most common cardiac anomaly (20-40%) congenital heart defect, and 50% are associated with another anomaly
Location
Membranous 80% - associated with tetralogy, truncus
Muscular 10%
Outlet 5% - often associated with aortic insufficiency
Inlet 5% - component of AVSD or endocardial cushion defect
Karyotype if associated extra-cardiac anomaly (trisomy, Holt Oram)
Monitor growth
Many are undetected, and only appreciable at birth or beyond
50% close spontaneously, may need surgical closure especially if large with shunting
Holt Oram – heart hand syndrome – ASD/VSD and upper limb abnormalities

33. Title

34. VSD Imaging findings: May see defect in b mode – echogenic edge
Needs to be seen in 2 planes
Doppler – may be only clue
Bi directional shunt as right and left ventricular pressures similar in fetus
If unidirectional, look for other cardiac anomaly altering ventricular pressures

35. VSD

36. VSD

37. VSD

38. AVSD/Endocardial Cushion Defect
EC forms lower atrial septum, superior ventricular septum, anterior MV leaflet and septal TV leaflet
Central heart defect involving
Atrial septum
Ventricular septum
Atrioventricular valves
Conducting system
Spectrum – partial more common than complete in newborns
2-7% of congenital heart defects
High association with aneuploidy
40% have trisomy 21

39. AVSD
Imaging findings
Single AV valve makes solid line across heart in systole (normally there is an offset of 2mm between valves)
Atrial and ventricular septal defect – b mode and Doppler
Arrhythmia – especially CHB
Additional cardiac malformations are common
Tetralogy of fallot
Pulmonary stenosis
Left heart/LVOT obstruction
AV regurgitation
Fetal heart failure and hydrops (poor prognosis)

40. AVSD/Endocardial Cushion Defect

41. Ebstein’s Anomaly
Septal and posterior leaflets of tricuspid valve prolapse and are integrated into RV wall
Atrialisation of RV
Large RA due to massive regurg
Maternal lithium is a risk factor

42. Hypoplastic Left Heart Syndrome
Small/hypoplastic left ventricle, associated with
Aortic atresia/stenosis
Mitral atresia/stenosis
Hypoplastic ascending aorta
9% of congenital heart defects
Associated with chromosomal abnormalities in 2-10%, particularly Turner’s, karyotype should be considered
Prognosis: 20% fetal demise, long term survival 30years with surgical treatment, otherwise rapidly (weeks) fatal
Imaging:
Small left ventricle with poor contraction (4 chamber)
Normal right ventricle
Bowing of atrial septa to right, minimal flow across mitral valve
Small ascending aorta with minimal flow across aortic valve

43. Hypoplastic Left Heart Syndrome

44. LVOTO Obstruction to flow across the aortic valve
Valvular
Subvalvular
Supravalvular
2-3% of congenital heart defects
Associated with chromosomal abnormalities, particularly supravalvular (Turner’s, William’s syndrome)
Prognosis depends on severity and surgical intervention, in extreme cases may consider fetal balloon valvuloplasty

45. LVOTO Imaging features
Variable size of left ventricle, usually with reduced function
May see RV hypertrophy to compensate
Turbulent Doppler flow across LVOT
MR from increased LV pressure
Left to right flow (shunting) across foramen ovale
Subvalvular
Muscular: asymmetrical septal hypertrophy
Membranous: membrane from septum to mitral valve
Valvular
Thickened valve leaflets (often bicuspid)
Supravalvular
Narrow/stenosis in proximal ascending aorta

46. Pulmonary Atresia
Hypoplastic RA and RV
Pulmonary artery calibre may be normal
Reversed flow in DA

47. Persistent Truncus Arteriosus
Single vessel overriding outflow valves and feeding aorta and pulmonary artery
1% of congenital heart defects
Almost always associated with a VSD, right sided arch in 30% of cases
Needs early surgical correction to avoid pulmonary HTN, excellent prognosis with surgery
High association with 22q11 deletion – karyotype for recurrence risk
Association with maternal diabetes
Imaging
Failure of normal crossing of great vessels
Single truncus vessel dividing into aorta and pulmonary artery

48. Truncus Arteriosus

49. Transposition of Great Vessels
5 % of congenital heart defects
Rare association with aneuploidy
There is an association with maternal diabetes
Excellent prognosis
Imaging
Careful orientation required
Failure of vessels to cross
Vessels arising from either side of the septum

50. Transposition of Great Vessels
Aorta arises from RV and pulmonary trunk from LV
Aorta and pulmonary artery are parallel instead of perpendicular to each other
Give Prostaglandin E1 to keep DA open

51. Transposition of Great Vessels

53. Tetralogy of Fallot 3-7% of congenital heart defects 4 components
Right ventricular outflow tract obstruction
VSD
Overriding aorta
Right ventricular hypertrophy
Associated with chromosomal abnormalities in 45% cases, and fetal cases should be karyotyped
Trisomy 21
Trisomy 18 and 13
PKU
Excellent prognosis in the absence of chromosomal abnormality

54. Tetralogy of Fallot Imaging: 4 chamber view normal in most cases
Large aortic outflow (due to VSD and RVOT obstruction)
Aortic root overriding VSD
RVOT obstruction
Abnormal pulmonary valve
Small pulmonary annulus
Turbulent flow in RVOT
Abnormal ductus arteriosis – small or absent
Heart failure and hydrops

55. Double Outlet Right Ventricle
Both great arteries arise partially or completely from right ventricle
1-2% of congenital hear defects
Nearly always associated with a VSD
High association with chromosomal abnormalities (18&13)
Good prognosis with surgery in the absence of chromosomal abnormalities
Imaging
Usually not evident on 4 chamber view
Great vessels are parallel (do not cross)
Both aorta and PA arise from right ventricle
Need to show both on one side of septum to differentiate between transposition

56. Endocardial Fibroelastosis
Increased echogenicity of endocardium
Ventricular dilatation and poor contractility
Ectopia Cordis

57. Strong association with Tuberous Sclerosis
Rhabdomyoma
Hamartoma of myocytes
Strong association with Tuberous Sclerosis
50-85% of fetuses with it have TS
50% of TS have it
Echogenic mass, usually intraventricular, can arise from IV septum

58. Arrhythmia 1-2% pregnancies, <10% are significant
Premature atria or ventricular contraction –
transient and benign,
account for over 90% or arrhythmias
Need no treatment, but advise to reduce caffeine, nicotine
Monitor weekly for SVT
SVT: 1 to 1 AV relationship
Most common tachyarrhythmia
Typical rate of
Treatment recommended to prevent hydrops
Digoxin 1st line (Flecanide, amiodarone, sotalol)
Atrial Flutter
Typical rate of
Variable AV block
Treat as for SVT

59. Arrhythmia Second degree heart block
Type 1 (Wencheback) – usually benign and does not progress to complete heart block
Type 2 (constant prolonged AV conduction time with dropped beats) – may progress to CHB
Monitor for CHB – no pharmacological therapy
Complete Heart Block
Association with maternal autoimmune diseases, and structural heart conditions
High mortality (20%)
Survivors nearly always need pacemaker
Pharmacological therapy in utero is limited and unproven
Fetal bradycardia (HR <100 for >10sec)
If persistent - consider structural cardiac defects or maternal CVD