Sonya V Babu – Narayan MB BS BSc MRCP c/o Department of CMR, Royal Brompton Hospital, London

1. How I do’ : CMR of patients after atrial redirection surgery for transposition of the great arteries Sonya V Babu – Narayan MB BS BSc MRCP c/o Department of CMR,Royal Brompton Hospital, London National Heart and Lung Institute, Imperial College London sonya@imperial.ac.uk Adaptation of presentation given at SCMR 2008

2. Outline Atrial Switch/ Redirection surgery Senning operation described 1959 Mustard operation described 1964 Long term problems after atrial switch for TGA and consequent goals of CMR assessment Practical suggestions as to how to achieve these goals

3. Surgery for transposition of the great arteries Atrial redirection surgery was performed prior to the availability of expertise to perform surgical arterial switch but may still be performed in selected cases or in patients deemed suitable for double switch for double discordance (ie atrial and arterial switch surgery). Illustrations from Brickner ME, Hillis LD, Lange RA. Congenital heart disease in adults. Second of two parts.N Engl J Med. 2000 Feb 3;342(5):334-42.

4. Long term problems after atrial redirection surgery – Mustard or Senning operation • Bradyarrhythmia • Tachyarrhythmia • Baffle obstruction • Baffle leak • Ventricular dysfunction • Sudden cardiac death

5. Initial Acquisition Multislice stack in transverse, sagittal and coronal • We do: transverse half Fourier TSE, and retrospectively gated SSFP for coronal + sagittal • transverse half Fourier TSE; easier to measure dimensions of structures such as aortic root and SSFP multislice gives advantage of jet recognition early on (jet flow is visible because signal is diminished where there is fluid shear due to dephasing caused by the presence of a range of velocities in a single voxel) Advantages of comprehensive multislice imaging include: • subsequent piloting of cines • ability to answer specific additional questions retrospectively • such as presence of LSVC otherwise missed? • location of coronary sinus prior to intervention?

6. CMR post atrial redirection surgery – assessing baffled atrial pathways 3D angiography can be used to assess all the atrial pathways with good results and may be easier when operator experience is limited Babu-Narayan, Johansson et al, JCMR supplement 2005

7. coronal cine stack may help with assessing the baffled atrial pathways- may also aid review by a second observer- however the ideal is that these challenging patients should only be imaged in centres with specific expertise and specific clinical expertise in their management Status post atrial redirection surgery– cine stack and CE-MRA

8. Atrial redirection surgery (Mustard / Senning) Operation CMR to image parallel outflow tracts CMR planes acquired to image atrial pathways White arrow points to baffle Black asterisk is in the pulmonary venous compartment Note the aorta is the more anterior vessel and the parallel nature of the outflow tracts Modified from: Brickner ME, Hillis LD, Lange RA. Congenital heart disease in adults. Second of two parts.N Engl J Med. 2000 Feb 3;342(5):334-42.

9. How to image the caval atrial pathways after atrial redirection surgery sagittal multislice superior vena caval and inferior vena caval pathways • Goal to align the plane of imaging to • the inflow axes of the atria You may now wish to append your first view and revise the plane relocating on these caval cross cuts to improve alignment further Caval pathway views in two planes provide data for alignment of velocity acquisitions

10. How to image the caval atrial pathways after atrial redirection surgery Cine image of superior vena caval and inferior vena caval pathways

11. How to image the pulmonary venous atrial pathways after atrial redirection surgery Cine of pulmonary venous atrial compartment This can be located from sagittal and coronal multislice as shown with the yellow bars (look for a “dumbell” shape on the sagittal and try and go through the apices on the coronal) sagittal multislice coronal multislice

12. CMR of the native outflow tracts– Ao and PA – in transposition of the great arteries Cine of parallel outflow tracts in transposition of the great arteries

13. CMR status post atrial redirection surgery - ? baffle pathway obstruction • Case 1: Systemic Venous Atrial Compartment • Severe SVC obstruction + mild IVC obst Superior limb obstruction > inferior limb obstruction Look for dilatation and reversal of flow in azygos Though Vmax >1m/s may suggest baffle pathway obstruction, this is not interpretable in isolation of the anatomy or remaining cardiac physiology

14. CMR status post atrial redirection surgery - ? baffle pathway obstruction • Case 2: Systemic Venous Atrial Compartment • SVC obstruction + mild IVC obst • A Vmax >1m/sec often suggests obstruction but avoid the pitfall of assuming this is the case IVC IVC Azy IVC Azy • In this example a peak velocity in the IVC limb > 1m/s (velocity map above) reflects higher volume of flow through this pathway as the other (SVC) limb is severely obstructed. It does not reflect severe IVC obstruction. Anatomically the IVC is only mildly narrowed (above). • Note the dilated on CEMRA (pictured left) and the reversed flow in the azygos (white arrow) on the velocity map (pictured top left).

15. CMR status post atrial redirection surgery – effect of intervention • Systemic Venous Atrial Compartment s/p SVC atrial pathway transcatheter stenting s/p IVC atrial pathway transcatheter stenting (The stent appears dark )

16. CMR status post atrial redirection surgery – effect of intervention SVC atrial pathway obstruction s/p SVC atrial pathway transcatheter stenting azygos (red arrow) no longer appears dilated)

17. CMR status post atrial redirection surgery - PVAC obstruction • Pulmonary Venous Atrial Compartment “hourglass” narrowing (black asterisk) Obstructed pulmonary venous atrial compartment (asterisk) Continuous flow on in-plane velocity mapping No “hourglass” narrowing, unobstructed * • ideally the peak velocity anywhere in the baffle pathways should not be > 1m/s • aliasing occurred at 1 m/sec and Vmax is 1.7m/s • continuous flow is seen in this significant stenosis (white arrow points at continuous jet)

18. CMR status post atrial redirection surgery - additional long axis views RV LV Ao PA PVAC LV RV Ao PA LV RA RV LA these views are typical in 20-40 year old adults after atrial redirection surgery adds to qualitative impression of ventricular size and function, views comparative with transthoracic and transoesphageal echocardiography and cardiac catheterisation (therefore familiar) therefore aids communication with clinicians demonstrates connections (educational)

19. Identifying residual VSD / patch leak Patch leak may be seen in: LVOT view RV in and out RV oblique views SA view as opposite If uncertain: cross-cut a SA view where a jet core is suspected Add Non-Breath-Hold velocity mapping: Aorta and PA (at sinotubular junction Ao and in main PA) Calculate Qp:Qs ratio Stroke volume ratio may be relevant

20. CMR status post atrial redirection surgery – look for residual VSD Use Ao PA velocity mapping to estimate shunt These cines demonstrate a residual VSD in the same patient (white arrow)

21. CMR status post atrial redirection surgery – look for subpulmonary stenosis Ao PA RV LV

22. CMR status post atrial redirection surgery– assess presence and degree of TR and AR • TR, AR and the Systemic RV Ao RV

23. CMR status post atrial redirection surgery– assess presence and degree of ventricular dysfunction • Systemic RV and Sub-Pulmonary LV Dysfunction RV

24. RV measurement in ACHD • RV trabeculations: • coarse, thickened and significant in summed volume • we do planimeter trabeculations, including them in the RV mass and excluding them from the blood pool • we count the septum as part of the systemic ventricle • our reproducibility is reported • planimetry challenging • use stroke volume as check • velocity mapping of Ao and Pa (these can usefully be obtained in a single acquisition as the outflow tracts are parallel) • a useful cross-check on manual contour data • for our centre’s method, interobserver and intraobserver variablity in this group of patients see Babu-Narayan SV, Goktekin O, Moon JC, Broberg CS, Pantely GA, Pennell DJ, Gatzoulis MA, Kilner PJ. Late gadolinium enhancement cardiovascular magnetic resonance of the systemic right ventricle in adults with previous atrial redirection surgery for transposition of the great arteries. Circulation. 2005 ;111:2091-2098 • Establish your own, reproducible protocol for the RV

25. CMR status post atrial redirection surgery - other Ao PA PA PA PA RV • Here the SVC limb is compressed by 7 cm diameter PA aneurysmal dilatation • Also note previously repaired fenestrated VSD (far left cine)

26. Summary of potential imaging choices for TGA post atrial redirection surgery All patients • Consider coronal ± tranaxial cine stack for review elsewhere • Cross cut SVC and IVC cines • Throughplane ± inplane flow SVC / IVC / PVAC • Throughplane ± inplane flow of azygos • Characterise any PS/VSD • Additional long axis ventricular views • 3D Truefisp and or 3D CE-MRA Consider • Multislice • Sagittal • Coronal • Tranaxial • Systemic venous compartment coronal cine • Pulmonary venous compartment cine (PVAC) • Outflow tracts cine • Short axis stack cines • Thrupl flow AO and PA (single acqusition)

27. Goals of CMR status post atrial redirection surgery – Take Home • presence, degree and functional significance of atrial pathway narrowing • Consider • anatomical size each limb • Velocity generally < 1m/sec • time course of flow ie continuous flow = obstruction • azygos dilatation • flow direction in azygos • ventricular function, (particularly systemic) • Consider • Presence of shunt • Residual VSD • Baffle leak • a condition possibly best imaged in, or at least with support from, experienced centres • If in doubt REFER

28. Acknowledgements • Illustration shows late gadolinium enhancement (arrows) in the systemic RV seen late after atrial redirection surgery • This may prove to have a risk stratification role* Philip J Kilner, Michael A Gatzoulis and Dudley J Pennell James Moon Craig S Broberg George Pantely Bengt Johansson Siew Yen Ho Christopher Lincoln Wei Li Tim Cannell Steve Collins Gill Smith Karen Symmonds Ricardo Wage Patients attending the Royal Brompton Hospital Adult Congenital Heart Disease Unit Staff of the Adult Congenital Heart Disease, CMR, Non Invasive Cardiology,Paediatric Cardiology, Paediatric Cardiac Surgery and Pathology Units See Refs: Babu-Narayan et al, Circulation 2005 Giardini et al, Am J Cardiol 2006