All You Need to Know About Situs and Looping Disorders: Embryology, Anatomy, and Echocardiography

Transcription

1 All You Need to Know About Situs and Looping Disorders: Embryology, Anatomy, and Echocardiography Helena Gardiner Co-Director of Fetal Cardiology, The Fetal Center, University of Texas at Houston

2 Situs abnormalities: learning objectives Recognise and identify the spectrum of sonographic features associated with abnormalities of situs Understand the importance of extracardiac abnormalities in counselling and perinatal management

3 Conflicts of interest none

4 Why is this topic about and why is it important? Abnormalities in determining left and right affect the heart, lungs and abdominal contents major CHD pulmonary atresia, aortic coarctation biliary atresia - early Kasai procedure volvulus - short mesentery - early abdominal surgery (prophylactic Ladd s) pacing heart block (10%) Association with ciliary disorders - Kartagener EARLY SURGERY AND LONG TERM CONSEQUENCES

5 Some features of left atrial isomerism Interrupted IVC with azygous continuation Unusual cardiac position: 30% to right, 10% midline Bilateral left atrial appendages Bilateral long left bronchi and bi-lobed lungs The liver is usually central with right -sided stomach Polysplenia Heart block Paediatric Cardiology, 3 rd edition. Eds Anderson RH, Baker EJ, Penny DJ, Redington AN, Rigby ML, Wernovsky G. Churchill Livingstone, 2010

6 Abdominal situs

7 (Hemi)azygous in left atrial isomerism Azygous (blue) lies posterior and rightward to the aorta (red)

8 (Hemi)azygous in left atrial isomerism Azygous (red) lies posterior to the aorta (aorta)

9 Venous connections No IVC entering the atrial mass

10 3VT view normal azygous SVC azygous duct Normal azygous connection to right SVC

11 3VT in left isomerism azygous SVC duct Enlarged azygous entering RSVC

12 Atrial Appendages

13 Atrial appendages in left atrial isomerism Usual atrial arrangement in a human fetal HREM specimen at 12+5 weeks Bilateral left atrial appendages in a mouse model Liat Gindes, Hikoro Matsui, Reuven Achiron, Timothy Mohun, Siew Yen Ho, Helena Gardiner. Ultrasound Obstet Gynecol. 39(2) (2012) Paediatric Cardiology, 3 rd edition. Eds Anderson RH, Baker EJ, Penny DJ, Redington AN, Rigby ML, Wernovsky G. Churchill Livingstone, 2010

14 Atrial morphology with interrupted IVC R LAA Ao R PA LAA Left atrial isomerism - left AAp seen on right - heart block Left atrial isomerism - bilateral left AAp - coronal view

15 4 chamber and outflow tract views These may be normal

16 Great arteries in left atrial isomerism RSVC Usually concordant Check for coarctation arch duct LSVC

17 AVSD common: biventricular AV connection Right hand topology (RV on fetal right), note heart block and non-compaction identified by deep fissures into the myocardium

18 Unbalanced: univentricular AV connection Left atrial isomerism, atretic left AV connection with a dominant anterior right ventricle. Double outlet with malposed great arteries and pulmonary stenosis

19 Venous connections

20 Pulmonary veins forming a confluence and entering the atrial mass Venous connections

21 Some of the myths about left isomerism Bilateral left atrial appendages are always seen with interrupted IVC There are always bilateral long bronchi and bi-lobed lungs The liver is usually central with right -sided stomach There is invariably polysplenia Paediatric Cardiology, 3 rd edition. Eds Anderson RH, Baker EJ, Penny DJ, Redington AN, Rigby ML, Wernovsky G. Churchill Livingstone, 2010

22 Azygous with heart stomach heterotaxy RA R Breech position: stomach on right, azygous on right and cardiac apex to left Atrial identity right atrium on right and left atrium on left usual atrial arrangement

23 Right Atrial Isomerism

24 Some features of right atrial isomerism Aorta and IVC usually on same side of spine Bilateral right atrial appendages Bilateral short right bronchi and tri-lobed lungs The liver is usually central with small posterior stomach Asplenia Paediatric Cardiology, 3 rd edition. Eds Anderson RH, Baker EJ, Penny DJ, Redington AN, Rigby ML, Wernovsky G. Churchill Livingstone, 2010

25 Bilateral right atrial appendages Usual atrial arrangement in a human fetal HREM specimen at 12+5 weeks Liat Gindes, Hikoro Matsui, Reuven Achiron, Timothy Mohun, Siew Yen Ho, Helena Gardiner. Ultrasound Obstet Gynecol. 39(2) (2012)

26 Abdominal situs

27 Usually aorta and IVC same side of spine R Pulmonary veins may descend below diaphragm

28 4 chamber and outflow tract views

29 Isomerism the 4 chamber view Clues L R Apex to right AVSD Symmetrical atrial wall Space behind the heart is increased (distance between spine and left atrium)

30 Atrioventricular junction: biventricular AV connection R Right hand topology: RV on fetal right

31 Great arteries in right atrial isomerism Often malposed Pulmonary atresia

32 Venous connections

33 Pulmonary venous connections Desc. vein Often a descending vein draining below diaphragm to portal sinus Here there were 2 descending veins!

34 RAI: LSVC draining to atrial mass 3VT has 4 vessels persistent LSVC Unlike the usual atrial arrangement this drains into the atrial mass, rather than the coronary sinus This is seen in the 4 chamber view

35 LAI: LSVC draining to coronary sinus

36 Conduction tissue Left: dysplastic node located near AV junction causing CHB in ~10% Right: dual SA nodes causing arrhythmia

37 Prenatal Counselling Multidisciplinary discussion of likely multiple organ involvement Karyotype likely to be normal Serial assessment for heart block/hydrops Planned delivery to manage obstructed lesions optimally pulmonary venous obstruction may be difficult to diagnose prenatally C/S if there is complete heart block

38 Postnatal Management Planned delivery as indicated by prenatal findings with MDT experts available Assess any obstructive lesions - CoA, PS, pulmonary veins, bowel ECG to assess heart rhythm - low atrial rhythm, ectopic, junctional - CHB (10%) drugs/pacing Exclude biliary atresia - Ladd s Infant repair of septal defects - AVSD

39 Conclusions: changing profile of isomerism Prenatal sonographic expertise identifies more variability in diagnostic features Prediction of obstructive lesions is improving - CoA, pulmonary veins, bowel Perinatal delivery should therefore be more organized and safer Intrinsically isomerism is a multi-organ disorder and outcomes remain guarded