CT approach to complications following endovascular stentgrafting of thoracic and abdominal aorta

Transcription

1 CT approach to complications following endovascular stentgrafting of thoracic and abdominal aorta Poster No.: C-1296 Congress: ECR 2011 Type: Educational Exhibit Authors: M. D. R. Matos, P. Ananias, H. M. R. Marques, O. Fernandes ; Lisboa/PT, Lisbon/PT Keywords: Complications, CT-High Resolution, CT-Angiography, CT, Arteries / Aorta, Vascular, Aneurysms, Dissection DOI: /ecr2011/C-1296 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 25

2 Learning objectives Multidetector CT technique is presented as a method for postoperative assessment of aortic stent-grafts. To present CT findings on complications of endovascular aortic repair. Background Endovascular repair has been adopted as an alternative to surgery in the treatment of aortic aneurysms, with significantly lower associated morbidity and mortality. Aortic aneurysms - definitions and epidemiology Localized and permanent enlargement of an artery, more than 1.5 times the expected diameter More common in the aorta (Ao), specially the infra-renal Aneurysm if the ascending aorta and aortic arch # 4cm, the descendant # 3.5 cm, and the infrarenal # 3 cm Aneurysms of the thoracic aorta (TAA): incidence 6/ person-years Abdominal Aorta Aneurysms (AAA): prevelance is 3 to 10% 12% of patients with AAA also have TAA 60% of patients with TAA have other aneurysms, including AAA Most feared complication: rupture. In AAA, expansion is 10% annually. Mortality after elective surgery is 5% and after rupture is 50% Aortic aneurysms - classification Localization Root Sinus of Valsalva Ascending aorta Arch Descending thoracic aorta Abdominal aorta Morphology Fusiform (circunferencioal, fig.1 on page 5) Page 2 of 25

3 Saccular (asymmetric) True aneurysms: involve all three layers of the wall Pseudoaneurysm: breaking through the 3 layers of the wall Etiology Congenital Acquired Atherosclerosis (+++) Cystic degeneration Infection Trauma Iatrogenic Inflammation Secondary to penetrating ulcer, dissection Treatment options for Aorta aneurysms Surgery Endovascular Prosthesis...Both Medical/ Expectant Depending on: Surgical risk Segment involved Association with valvular disease Need for repair aorta branches (coronary vessels, eg.) When to repair Aorta Aneurysms TAA The aneurysm has reached a diameter # 2.5 times the diameter of the adjacent Ao Aneurysm reaches a diameter # 6-7cm Regardless of size: in the presence of embolization, rapid expansion, pain or other symptoms In the presence of connective tissue disease (SD Marfan, Ehlers-Danlos syndrome), if # 5.5 cm AAA Page 3 of 25

4 Anteroposterior external diameter # 5.5 cm ENDOVASCULAR AORTIC PROSTHESES Dotter - origin of the concept of endovascular prosthesis. Animal experiments Parodi et al - Early prostheses in humans, transfemoral approach Scott and Chutter - First bifurcated endovascular aortic stent Advantages over Surgery less blood loss lower length of stay Lower recovery time Lower mortality rate SURGICAL TREATMENT VERSUS ENDOPROSTHESIS TAA Ascendant: surgery Descending: vascular stent (figs.2 on page 5 and 3 on page 6) Aortic Arch: Possible combination of both AAA Infra-renal (most AAA, beginning # 1cm renal vascular pedicle): vascular stent Juxtarenal (<1 cm from the renal pedicle) or supra-renal: surgery Computed Tomography (CT) - Follow-up No contrast Arterial phase Late Phase 1 month, 3 months, 6months, 1 year after endographting # ANNUAL Collimation in the arterial phase, in the first study: 0.5 to 1.25 mm. Acquisition with no contrast and late stage: 2 to 3mm Page 4 of 25

5 Injection time and bolus acquisition interval sufficient to raise Ao attenuation to HU Axial cine mode, MIP, VR, multiplanar reformatting and curvilinear reformatting (fig. 4 on page 7) Images for this section: Fig. 1: Fusiform aneurysm of the ascending aorta Page 5 of 25

6 Fig. 2: Endovascular procedure: image from digital subtraction angiography shows a saccular aneurysm of the descending thoracic aorta Page 6 of 25

7 Fig. 3: Post-procedure digital subtraction angiography image shows complete exclusion of the aneurysmal sac Page 7 of 25

8 Fig. 4: Contrast enhanced helical CT, axial image (A), color-coded 3D volume-rendered (B, C), sagittal (C) and coronal (D) 3D volume-rendered images. All showing abdominal aortic stent graft in situ Page 8 of 25

9 Imaging findings OR Procedure details CT in the follow-up of Aorta Stent Grafting It must include: Measurement of maximum external anteroposterior and transverse diameters of the aneurysm Endoluminal measurement of aortic or aorto-bi-iliac stent In the presence of AAA, the distance between the proximal stent margin and lower margin of the lowest renal artery; distance between the lower margin and the iliac bifurcation Size of the aneurysmatic sac in successive studies Thrombosis Patency and position of the prosthesis Detection of complications Complications Endoleaks Thrombosis kinking of the prosthesis Organ ischemia Pseudoaneurysm or aortic dissection Infection Occlusion of the prosthesis Hematoma at the Arteriotomy Site Stent malposition or migration Shower Embolism Endoleaks (most common complication) Persistence of blood flow outside the lumen of the endoluminal graft but within an aneurysm sac or the adjacent vascular segment being treated with the graft. Type I endoeak (figs.1 on page 11, 2 on page 12, 3 on page 13 and 4 on page 14) - incomplete fixation of the prosthesis to the aortic wall (IA - proximal or IB - distal) Page 9 of 25

10 Type II endoleak (figs.5 on page 15, 6 on page 16, 7 on page 17, 8 on page 18 and 9 on page 19) - retrograde flow from patent vessel Type III endoleak (fig. 10 on page 20) - structural failure of the stent grid with reflux through prosthesis Type IV endoleak - residual perfusion, due to porosity of the prosthesis Type V endoleak - continued expansion of the aneurysm sac ("endotension ") without an identifiable cause in CT Graft Thrombosis On contraste enhanc ed CT, graft thrombosis is recognized as an intraluminal, parietal, circular, or semicircular not enhanced area within the stent-graft (fig. 11 on page 20) Graft kinking When large aneurysms decrease in diameter after endovascular repair, they also decrease in length. This shortening may lead to the development of a kink in the stentgraft (fig. 12 on page 21) Organ Ischemia A feared complication of endovascular stent-graft implantation to treat infrarenal abdominal aortic aneurysm is organ ischemia. Special attention should be given to colon necrosis (figs. 9 on page 19, 13 on page 22) Pseudoaneurysm or Dissection The aortic wall is fragile, which may lead to a pseudoaneurysm at either end of the endostent. Stents can also produce dissection of the surrounding vessel Graft Infection Page 10 of 25

11 Graft infection is occasionally observed sometime after the procedure. The outcome of no treatment of aortic stent-graft infection or treatment with exclusive antibiotics is invariably fatal. Periprosthetic thickening with soft-tissue attenuation at follow-up CT does not always indicate graft infection, and diagnosis of graft infections may be difficult Graft Occlusion Stenosis of the iliac graft limb is reported in a series of bifurcated grafts not fully supported by stents, but graft occlusion is a relatively rare event after stent-graft implantation Hematoma at the Arteriotomy Site Usually develops under conditions of manifest hypocoagulability and often requires surgical repair (fig. 14 on page 22) Stent Malposition or Migration Malpositioning often results from elevated blood pressure during stent deployment or when the stent is being placed across an angulated segment. In either instance, the primary pathologic condition may no longer be appropriately treated. Also, malpositioning or stent migration may result in inadvertent coverage of an important branch vessel Shower Embolism It is one of the most serious, possibly fatal complications after conventional repair of infrarenal abdominal aortic aneurysm and is relatively rare. Shower embolism occurs more frequently after endovascular aneurysm repair than after conventional open surgery Images for this section: Page 11 of 25

12 Fig. 1: Contrast enhanced CT sagittal MPR image (A) and color-coded 3D volume rendered image (B) show a type B aortic dissection which begins just past the left subclavian artery Page 12 of 25

13 Fig. 2: Same patient as fig.1 - Axial contraste enhanced CT images 1 week following endovascular procedure show a proximal endoleak (type IA) Page 13 of 25

14 Fig. 3: Same patient as figs.1,2 - Sagittal MPR image (A) and sagittal color-coded 3D volume-rendered from contrast-enhanced CT 1 week following endovascular procedure show a proximal endoleak (type IA) Page 14 of 25

15 Fig. 4: Axial helical CT scan obtained 1 week after treatment in another patient show a distal leak (type IB) due to insufficient anchorage of the prosthesis at the level of the right common iliac artery Page 15 of 25

16 Fig. 5: Axial (A) and sagittal MPR (B) images of helical CT scan show endoleak caused by collateral flow from patent superior mesenteric artery Page 16 of 25

17 Fig. 6: Axial helical CT images show and endoleak caused by collateral flow from patent distal lumbar artery Page 17 of 25

18 Fig. 7: Same patient as fig. 6 - coronal MPR view of helical CT show and endoleak caused by collateral flow from patent distal lumbar artery Page 18 of 25

19 Fig. 8: Axial (A) and sagittal MPR (B) images of contrast enhanced helical CT show endoleak caused by collateral flow from patent inferior mesenteric artery Fig. 9: Axial (A) image of helical CT shows an endoleak caused by collateral flow from the patent right hypogastric mesenteric artery. An attempt was made to embolize the artery, Page 19 of 25

20 without success. Coronal MPR (B) image shows resultant hematoma. These patient had associated colon ischemia Fig. 10: Axial (A) and sagittal MPR images (B,C) of helical contrast enhanced CT show an endoleak caused by reflux through the stent (type III) Page 20 of 25

21 Fig. 11: Axial contrast enhanced CT image showing parcial graft thrombosis, recognized as an intraluminal, semicircular not enhanced area within the stent-graft Page 21 of 25

22 Fig. 12: Axial (B) and sagittal MPR images (B,C) of helical contrast enhanced CT show distal graft kinking after stent-graft implantation in a patient with a thoracic aortic aneurysm Fig. 13: Axial helical contrast enhanced CT image shows nonenhancing right renal artery and right kidney ischemia following stent treatment of an abdominal aortic aneurysm Page 22 of 25

23 Fig. 14: Hematoma following endografting of an abdominal aortic aneurysm. Follow-up axial CT image obtained after stent-graft implantation shows a large highattenuating area in the left sided pelvis Page 23 of 25

24 Conclusion CT is a quick, minimally invasive, first line exam in the evaluation of endovascular aortic repair. Multiplanar reconstructions permit the assessment of the prothesis configuration, associated anomalies, and exclusion of flow in the offending lesion. Personal Information Thank you for revealing interest in this exhibit. I am available for any questions or comments via (matosb.maria@gmail.com). References Toshifumi Mita, MD et al, Complications of Endovascular Repair for Thoracic and Abdominal Aortic Aneurysm: An Imaging Spectrum. RadioGraphics 2000; 20: Manfred T, MD et al, Helical CT Angiography of Stent-grafts in Abdominal Aortic Aneurysms: Morphologic Changes and Complications. RadioGraphics 1999; 19: Jafar Golzarian, David Valenti, Endoleakage after endovascular treatment of abdominal aortic aneurysms: diagnosis, significance and treatment. Eur Radiology (2006); 16: Marchelle J. Bean, MD et al, Thoracic Aortic Stent-Grafts: Utility of Multidetector CT for Pre and Postprocedure Evaluation. RadioGraphics 2008; 28: John Rose, Stent-Grafts for Unruptured Abdominal Aortic Aneurysms: Current Status. CardioVascular and Interventional Radiology (2006). 29: Gonzalo Garzon, MD, et al, Graft Treatment of Thoracic Aortic Disease. RadioGraphics 2005; 25:S229-S244 Page 24 of 25

25 Geoffrey D. Rubin, Niel M. Rofsky, CT and MR Angiography: Comprehensive Vascular Assessment. Lippincott Williams & Wilkins,US; 1 edition (1 Aug 2008) Page 25 of 25