How to plan a Zenith AAA stent-graft from a CTA: Basic measurements and concepts explained

Transcription

1 How to plan a Zenith AAA stent-graft from a CTA: Basic measurements and concepts explained Poster No.: C-3077 Congress: ECR 2010 Type: Educational Exhibit Topic: Vascular Authors: D. V. Thomas; Northampton/UK Keywords: Zenith Flex stent graft, Planning an EVAR, CT Aortogram DOI: /ecr2010/C-3077 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 21

2 Learning objectives To understand the basic concepts and methodology in the planning of a Zenith Flex AAA stent graft from a multi-detector row computed tomography angiogram (CTA) of the abdominal aorta. This is illustrated by an example with appropriate CTA images and calculations according to our departmental Zenith Flex planning sheet. Background Endovascular stent-graft repair (EVAR) of abdominal aortic aneurysms (AAA) is a rapidly growing option in the treatment of AAA. It is important that all interventional radiologists and vascular surgeons who are involved in setting up an EVAR service are familiar with the basic measurements and concepts used to plan an appropriately sized aortic stent graft from a CT angiogram of the aorta. Zenith-Flex is the latest version of the popular stent graft from Cook Ltd. An example is used to illustrate how this graft may be planned from a CTA. Imaging findings OR Procedure details The important points to note when evaluating a CT angiogram for an endovascular stent graft may be grouped as follows Anatomical suitability. Measurements required to plan the graft - This will be covered in this presentation with an example. Presence of other aneurysms. Presence of any other pathology in the abdomen. This presentation is mainly to illustrate the process of planning a Zenith-Flex endovascular AAA stent-graft from the CT angiogram. Evaluation of suitability and other factors or steps of stent deployment are beyond the remit of this presentation. Page 2 of 21

3 Zenith Flex AAA Stent Graft This is a woven polyester graft sutured to a frame of self-expanding stainless steel stents and contained within a delivery system (H&LB One-shot Introduction System). The graft consists of three parts - a main body and two iliac limbs. Another available option is the aorto-uni-iliac graft consisting of a body and a single iliac limb. Page 3 of 21

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5 Fig.: Main body References: Cook Ltd Iliac limb Page 5 of 21

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7 Fig.: Iliac Limb References: Cook Ltd Recommended measurements for suitability Fig.: Recommended measurements for suitability References: Cook Ltd Measurements Page 7 of 21

8 The basic measurements are as follows Diameter at the level of the renal arteries - D1 Diameter of the ipsilateral common iliac artery - D2 Diameter of the contralateral common iliac artery - D3 Length from the level of the renal arteries to the aortic bifurcation - L1 Length from the level of the renal arteries to the ipsilateral CIA deployment zone - L2 Length from the level of the renal arteries to the contralateral CIA deployment zone - L3 In addition, the diameter of the external iliac arteries are also calculated to ensure that these are wide enough for the device (>7mm). The measurements should ideally be taken from a good quality CT angiogram. Axial and curved reformat images are used. A curved reformat along the centre-line will take any vessel tortuosity into account as well. The above measurements are then used in the planning sheet and based on these, the appropriate device components can be selected. Note - Ipsilateral - this is usually the right side as the main body is usually deployed up the right side. The left side is therefore Contralateral. Care should be taken to reverse the designation of measurements and plan if the main body is deployed up the left side. Sample plan An example of a plan done for one of our patients recently is as followsd1 - diameter at lowest renal artery = 21mm Page 8 of 21

9 Fig.: D1 References: D. V. Thomas; Dept of Radiology, Northampton General Hospital, Northampton, UNITED KINGDOM D2 - diameter at the ipsilateral CIA landing zone (right) = 12mm Page 9 of 21

10 Fig.: D2 References: D. V. Thomas; Dept of Radiology, Northampton General Hospital, Northampton, UNITED KINGDOM D3 - diameter at the contralateral CIA landing zone (left)= 13mm Page 10 of 21

11 Fig.: D3 References: D. V. Thomas; Dept of Radiology, Northampton General Hospital, Northampton, UNITED KINGDOM L1 - length from lowest renal artery to aortic bifurcation= 128mm Page 11 of 21

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13 Fig.: L1 References: D. V. Thomas; Dept of Radiology, Northampton General Hospital, Northampton, UNITED KINGDOM Ipsilateral - this is usually the right side as the main body is usually deployed up the right side. Care should be taken with planning and the measurements if the main body is deployed up the left side. L2 - length from lowest renal artery to ipsilateral CIA landing zone= 188mm Page 13 of 21

14 Fig.: L2 Page 14 of 21

15 References: D. V. Thomas; Dept of Radiology, Northampton General Hospital, Northampton, UNITED KINGDOM L3 - length from lowest renal artery to contralateral CIA landing zone= 204mm Page 15 of 21

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17 Fig.: L3 References: D. V. Thomas; Dept of Radiology, Northampton General Hospital, Northampton, UNITED KINGDOM Calculations - (See full planning sheet in the side bar). Main body To calculate the main body size, D1 needs to be oversized as follows - (Our example is in bold type) D1 vessel Stent L1 = CL limb mm IL limb mm TFFB-diameter TFFB-diameter TFFB-diameter TFFB-diameter TFFB-diameter Note - Although the L1 is 128 (and therefore a 125 body is possible), I would opt for a 111mm body to give a bit more room for manouvere. Hence the main body is TFFB Now we need to calculate the limb sizes. Page 17 of 21

18 Recommended diameter oversizing for the limbs are as shown - (again our example is in bold type) Vessel Stent or or or Available limb lengths for diameter diameter The diameter for the right limb based on a D2 of 12 would be 14mm and the diameter of the left limb based on a D3 of 13 would be 16mm. Limb Lengths The body-limb overlaps is built into the design. Our working limb length for the right side is L2-IL (Ipsilateral lim)b ie = 47mm. So I would opt for a 56mm limb length. Therefore our right limb is TFLE Page 18 of 21

19 Similarly the working limb length on the left is L3-CL (Contralateral limb) ie = 93mm. A 90mm limb length would be sufficient. So our left limb is TFLE The final order is therefore Main body - TFFB Right limb - TFLE Left limb - TFLE Images for this section: Page 19 of 21

20 Fig. 1: Planning Sheet Zenith Flex Main body and Legs Page 20 of 21

21 Conclusion An understanding of the required measurements and basic concepts used to plan an EVAR from a CTA is vital for all interventional radiologists and vascular surgeons. With the help of an example, this has been illustrated in this presentation. Although seemingly complex, once the basic principles are understood, then planning and sizing becomes easy. Personal Information I am a vascular interventional radiologist based in Northampton, UK. I can be contacted by on - davis.thomas@ngh.nhs.uk. References Product feature, Catalogue page and Resource Library Component ordering information - mmedia/ai-bm-fxztcoi-en pdf Page 21 of 21