Analysis of Clinical Geometry and Biomarkers of Thoracic and Abdominal Aortic Stent Grafts in the Treatment of Aortic Aneurysms
Date Issued
2015
Date
2015
Author(s)
Wu, I-Hui
Abstract
This thesis mainly focuses on analysis of clinical geometry of thoracic and abdominal aortic stent grafts in the treatment of aortic aneurysms. Including (1) The Significance of Endograft Geometry on the Incidence of Intraprosthetic Thrombus Deposits after Abdominal Endovascular Grafting (2) Outcomes following endovascular or open repair for ruptured abdominal aortic aneurysm in a Chinese population (3) One-stage Hybrid Repair to Thoracoabdominal Aortic Aneurysm (4) Crossover Chimney Technique to Preserve the Internal Iliac Artery During Endovascular Repair of Iliac or Aortoiliac Aneurysms, and (5) How to size the main aortic endograft in a chimney procedure (1) The Significance of Endograft Geometry on the Incidence of Intraprosthetic Thrombus Deposits after Abdominal Endovascular Grafting Objectives: To examine the incidence and risk factors of intraprosthetic throm- botic deposits in abdominal aortic endografts. Methods: The clinical records of 51 patients (44 males; mean age 76.3 years, range: 63-90years) with abdominal aortic aneurysm treated with transfemoral implantation of bifurcated stent graft between the years 2002 and 2008 were retrospectively reviewed. Patients underwent three-phase helical computed tomographic (CT) examinations at 1-, 3-, 6- and 12-month intervals and then annually. The formation of intraprosthetic thrombus associated with use of anti-platelet, preoperative mural thrombus in the aneurysm, ratio of cross-sectional area between the mainbody and bilateral limb grafts and length of mainbody were evaluated. Results: Over a 10-month mean follow-up, intraluminal deposits of thrombotic material were observed in eight of 51 patients (15.6%, 95% confidence interval: 8.2-28). The first signs of thrombus formation occurred on average 9.8 months after endografting (range: 1-24 months).Intraprosthetic thrombotic deposits was not related to preoperative mural thrombus formation(p value: 0.38) or postoperative anti-platelet or anticoagulation medication (p﹦0.40). However, it was significantly related to the ratio of the cross-sectional area between the mainbody and the bilateral limb grafts and the length of mainbody (p﹦0.04 and p﹦0.01). There were three graft limbs occlusion owing to kinking with no intraprosthetic thrombus detected on CT scans taken prior to occlusion. One patient developed distal left proximal superior femoral artery embolisation 4 months after detectable intraprosthetic mainbody thrombus in a CT scan follow-up. In no case did the thrombotic deposits clear completely from the prosthesis lumen during follow-up. (2) Outcomes following endovascular or open repair for ruptured abdominal aortic aneurysm in a Chinese population 36 patients with RAAA undergoing either OAR or eEVAR in National Taiwan University Hospital from 2005 to 2012 were analyzed retrospectively. Thirty-five (97.2 %) patients were treated. Among them, 20 (57.1 %) were treated by OAR and 15 (42.9 %) by eEVAR. The overall 30-day survival rate was 77.1 %. There was no significant difference in 30-day mortality rate (OAR 15.0 % vs.eEVAR 33.3 %, p = 0.201) and midterm mortality rate (OAR 20.0 % vs. eEVAR 46.7 %, p = 0.093) between these two groups. On univariate analysis, free peritoneal rupture (p =0.001), pre-operative shock (p = 0.001) and female gender (p = 0.016) are related to a higher 30-day mortality rate, while free peritoneal rupture (p = 0.012) and pre-operative shock (p = 0.030) are associated with a higher midterm mortality rate in both repair techniques. On multivariate analysis, free peritoneal rupture was associated with higher 30-day (OR 26.0, 95 % CI 2.2–295.6,p = 0.009) and midterm (OR 13.1, 95 % CI 1.2–37.6,p = 0.032) mortality rates. In patients with RAAA, there is no significant difference in 30-day mortality and midterm mortality between eEVAR and OAR groups in our study. eEVAR could be an alternative therapy for anatomically suitable RAAA in a Chinese population. (3) One-stage Hybrid Repair to Thoracoabdominal Aortic Aneurysm This study represents our experience with 10 patients at a single center who underwent 1-stage visceral hybrid procedures for complex thoracoabdominal aortic pathologies. There were 9 men and 1 woman with a median age of 65.7 years. The average preoperative European System for Cardiac Operative Risk Evaluation II score was 34.1%. The technical success rate with completion was 100%. No procedure was abandoned because of any aortic event. The 30-day mortality rate in this study was 10%. Overall major peri-operative complication rates were 20%. Major complications included renal impairment requiring permanent support in 1 patient (10%) and paraplegia in 1 patient (10%). At a median follow-up of 20.1 months (range, 0.3e39 months), the overall survival rate was 70%. The primary graft patency rate was 96.8% (32/33). Only 1 renal artery graft was occluded. The midterm results in selected high-risk patients with TAAA undergoing 1-stage hybrid repair were encouraging. When open repair is hazardous and branched stent grafting is not an option, hybrid repair is a viable treatment alternative. (4) Crossover Chimney Technique to Preserve the Internal Iliac Artery During Endovascular Repair of Iliac or Aortoiliac Aneurysms Between May 2012 and January 2014, 14 consecutive patients (mean age 77.3 years; all men) with 17 AIA, isolated CIAAs, or abdominal aortic aneurysms with short CIAs underwent elective endovascular aneurysm repair (EVAR) with the crossover chimney technique to preserve the IIA. Follow-up assessment, including computed tomographic angiography or duplex ultrasound, was performed at 1, 6, and 12 months and annually thereafter. Technical success, defined as successful preservation of IIA without intraoperative type I or III endoleak, was 100%. Over a mean 14.3 months (range 6–21), primary patency was 92.8%. There was no early or late procedure-related mortality. Among the 17 iliac aneurysms excluded, the sac diameter significantly (at least 5 mm) decreased in 3, decreased <5 mm in 10, and did not change in 4. The crossover chimney technique is a simple and safe alternative for IIA endovascular revascularization with high technical success and acceptable midterm patency. (5) How to size the main aortic endograft in a chimney procedure The application of endovascular aortic repair in difficult circumstances, such as juxtarenal, pararenal, or thoracoabdominal aortic aneurysms is limited. To address this difficulty, the chimney technique has been expanded and applied widely. Other than the surgeon’s individual experience and preference, however, there is currently no consensus regarding how to choose the appropriate size for the main aortic graft (MAG) parallel to the visceral chimney graft (CG) so that they accommodate each other properly inside the native aorta. Isoperimetric inequality states that among all closed curves in the plane of a fixed perimeter, a circle maximizes the area of its enclosed region. In this study, we propose a mathematical formula that was based on isoperimetric inequality to select the size of the MAG inside a known diameter of the native aorta and visceral CG: R''≥√((1.44R^2-r^2)) where R’is the radius of the MAG, R is the radius of the native aorta, and r is the radius of the CG.
Subjects
Ruptured abdominal aortic aneurysm
Endovascular aneurysm repair abdominal aortic aneurysm
common iliac artery aneurysm
internal iliac artery
chimney graft
Type
thesis