Post-Op Aorta: Differentiating Normal Post-Op vs. Complications. Linda C. Chu, MD Assistant Professor of Radiology Johns Hopkins University

Transcription

1 Post-Op Aorta: Differentiating Normal Post-Op vs. Complications Linda C. Chu, MD Assistant Professor of Radiology Johns Hopkins University

2 No disclosures Disclosures

3 Goals and Objectives To review CT technique in post-operative evaluation following aortic root replacement To provide a systematic approach in the evaluation of post-op aorta To emphasize features helpful in differentiating normal post-op vs. complications

4 Introduction Composite aortic valve conduit replacement was first introduced in 1968 Surgical modifications and technical improvements during past 4 decades have made aortic root replacement safe and reproducible Expected mortality in elective aortic root repair < 5% Patients are still at risk of developing early and late term complications Bentall H. et al. Thorax 1968;23: Sioris T. et al. J Thorac Cardiovasc Surg 2004;128:

5 Aortic Root Replacement Procedures Interposition graft: Excision of native aorta End-to-end anastomosis with biological or synthetic graft Composite graft Includes artificial valve Valve sparing Keeps native aortic valve Inclusion graft: Native aorta is wrapped around synthetic graft

6 Normal Post-Op

7 Not So Normal Post-Op

8 CT Technique Choices CT without intravenous contrast CT with intravenous contrast Arterial phase Arterial phase and delayed phase ECG-gating

9 CT Technique IV Contrast IV contrast is critical in detection of postop complications such as pseudoaneurysm or dissection Retrosternal fluid collection Pseudoaneurysm

10 CT Technique IV Contrast At our institution, non-contrast CT is not performed for routine surveillance of post-op aorta patients Non-contrast CT can be helpful in certain situations: Stent grafts (r/o endoleak) Acute chest pain (r/o intramural hematoma) Differentiating surgical hardware from leak Pseudoaneurysm? Hyperdense surgical material

11 CT Technique ECG-Gating Important to perform ECG-gating to minimize motion at the aortic root Motion artifact on a normal study Subtle pseudoaneurysm on a non-ecg gated study Clear depiction of pseudoaneurysm on ECG-gated study

12 CT Technique ECG-Gating Subtle pseudoaneurysm missed on non-ecg gated study Pseudoaneurysm missed on outside non-ecg gated study Clear depiction of pseudoaneurysm on ECG-gated study

13 Post-Op Aorta Check List Aorta and graft Coronary arteries Aortic valve Mediastinum and pericardium Lungs and pleura Sternum and soft tissues Support devices

14 Aorta and Graft Vessel diameter Vessel contour Anastomosis and cannulation sites

15 Vessel Diameter and Contour Patients with history of aortic root replacement may develop progressive aortic aneurysm or dissection Patients with underlying connective tissue disorders are at increased risk for progression Marfan pt with residual aortic dissection following aortic root replacement Worsening dissection and aneurysm on 1 year f/u exam

16 Vessel Diameter and Contour Monitor for progressive vessel enlargement Measure on comparable levels Double oblique MPR reformats Compare to more remote exams Slow growth over time May appear stable compared to most recent exam Monitor vessel contour New dissection Extension of preexisting dissection flap

17 Anastomosis and Cannulation Sites Carefully evaluate all anastomosis and cannulation sites to exclude pseudoaneurysm Abnormal outpouching of contrast at the anastomosis site MPR and 3D reconstructions

18 Pseudoaneurysms Pseudoaneurysms (PSA) tend to occur at anastomosis or cannulation sites A. Graft anastomosis B. Coronary artery anastomosis C. Aortotomy site D. Aortic cannulation site E. Needle vent site Malvindi, P.G. et al. Ann Thorac Surg 2010;89: Chu, L.C. et al. AJR 2012; 199:W84-90

19 Pseudoaneurysms PSA at valve anastomosis PSA at coronary artery anastomosis PSA at cannulation site

20 Pseudoaneurysm with Aortotracheal Fistula Rare and potentially fatal complication Effacement of fat plane with trachea Tend not to see active contrast extravasation PSA near graft anastomosis, dx as tracheal polyp Irregular contour of tracheal wall

21 Pseudoaneurysms Specify location of pseudoaneurysm with respect to aortic root and coronary arteries Provide size and number of pseudoaneurysms Indicators of acute hemorrhage Presence of additional aortic abnormality that require intervention Distance of pseudoaneurysm from sternum Helps assess risk for resternotomy

22 Risk of Pseudoaneurysm Rupture Higher risk for reentry: Anterior pseudoaneurysm < 2 cm from sternum Need to establish cardiopulmonary bypass before resternotomy Malvindi P.G. et al. Ann Thorac Surg 2010;89: Settepani F. et al. J Card Surg 2008;23:

23 Risk of Pseudoaneurysm Rupture Lower risk for reentry: Anterior pseudoaneurysm > 2 cm from sternum OR Posterior pseudoaneurysm Cardiopulmonary bypass before resternotomy is optional Malvindi P.G. et al. Ann Thorac Surg 2010;89: Settepani F. et al. J Card Surg 2008;23:

24 Coronary Arteries Evaluate morphology of coronary ostia Evaluate coronary arteries on axial, MPR, and MIP If patient has coronary artery graft Assess patency of graft

25 Coronary Ostial Aneurysm Dilatation of coronary artery reimplantation site > 10 mm Perioperative stretch of weakened ostial wall Increased risk in patients with connective tissue disorders Long-term consequences unknown Probably low risk finding Meijboom, L.J. et al. Am J Cardiol 2002;89:

26 Aortic Valve MPR reformat to evaluate valve leaftlet thickness and morphology Aortic valve function (retrospective gating)

27 Aortic Valve Endocarditis CT with ECG gating can reliably detect valvular vegetations > 1 cm Valvular thickening and nodular excresence Evaluate associated findings: Perivalvular pseudoenaurysm Septic emboli Endocarditis vegetation Perivalvular pseudoaneurysm Bennett C.L. et al. Radiographics 2012;32(5):

28 Aortic Valve Malfunction Prosthetic valve obstruction due to thrombus or pannus is a serious and occasionally fatal complication Incidence of prosthetic valve obstruction ~ 0.1% to 0.6% per patient-year Ueda T. et al. Circulation J 2013;77: Thrombi on stuck valve Anterior leaflet stuck in semiopen position, posterior leaflet with limited excursion

29 Mediastinum and Pericardium Amount and density of fluid Amount of gas Small amount of fluid or gas may persist for days or weeks Suspicious CT findings: Large amount of hypodense fluid Increasing fluid and soft tissue on serial scans Increasing gas Exarhos, D.N. Eur Radiol 2005;15: Carrol, C.L. J Comput Assist Tomogr 1987;11: Sundaram, B. Radiographics 2007;27:

30 Mediastinitis Difficult to differentiate between normal post-op vs. mediastinitis Most helpful clue: Increase in size or complexity on serial exams 1 week post-op: Small amount of fluid and air, expected post-op change 2 week post-op: Increased size of fluid collection and density Mediastinitis

31 Mediastinal Fluid Collection Beware of pseudoaneurysm masquerading as mediastinal fluid collection IV contrast is critical for thorough evaluation of post-op complications Retrosternal fluid collection Pseudoaneurysm

32 Perigraft Seroma Rare, late complication of polytetrafluoroethylene and Dacron grafts Failure of graft incorporation into native vessel wall and increased graft porosity After 3 months, any perigraft hematoma or fluid should have resolved May recur following simple aspiration and drainage Persistent recurrent perigraft fluid collection Ahn, S.S. et al. Am J Surg 1987;154: Kat E. et al. AJR 2002;178:

33 Lungs and Pleura Amount and density of pleural fluid CT with IV contrast may be able to identify source of bleeding in hemothorax Pneumothorax Lung consolidation

34 Sternum and Soft Tissues Integrity of sternal wires Alignment of sternum Sternal erosion Sternal periosteal reaction Soft tissue fluid collection

35 Sternal Dehiscence May occur alone or in association with mediastinitis Displacement of sternal wires Sternal erosion Cleft within sternotomy site Soft tissue hematoma Fragmented sternum Sternal cleft with pectoral hematoma Kaye, A.E. et al. Annals of Plastic Surgery 2010;64:

36 Sternal Osteomyelitis Complication seen in 2% of patients undergoing sternotomy Bone erosion and periosteal reaction Associated soft tissue infection Rim enhancing fluid collection Abscess Sternal erosion Osteomyelitis Restrepo, C.W. et al. Radiographics 2009;29:

37 Support Devices Check appropriate placement of all support devices

38 Conclusion Multidetector CT with ECG-gating can provide important diagnostic information in the evaluation of post-operative complications following aortic root replacement Systematic approach with attention to key CT features can help differentiate normal post-op from pathology

39 THANK YOU