Timothy A.M. Chuter

Intermediate results of a United States multicenter trial of fenestrated endograft repair for juxtarenal abdominal aortic aneurysms

OBJECTIVE This article reports the intermediate-term (24-month) outcomes of a prospective multicenter trial designed to evaluate the Zenith Fenestrated AAA Endovascular Graft (Cook Medical, Bloomington, Ind) for treating juxtarenal abdominal aortic aneurysms with short proximal necks. The study goals were to evaluate the safety and preliminary effectiveness of the device and refine patient selection criteria. METHODS Five centers in the United States enrolled 30 patients with juxtarenal aortic aneurysms with >or=50-mm diameter and short proximal necks. Devices were custom-designed for each patient based on measurements from reconstructed computed tomography (CT) data. Follow-up studies included physical examinations, laboratory studies, CT imaging, mesenteric-renal duplex ultrasound imaging, and abdominal flat plate radiographs at hospital discharge, at 1, 6, and 12 months, and yearly thereafter up to 5 years. RESULTS During a 1-year period, 30 patients (80% men; mean age, 75 years) with a mean aneurysm size of 61.4 mm were enrolled. In these 30 patients, 77 visceral vessels were accommodated by fenestrations located within the sealing segment of the grafts. The most common design accommodated two renal arteries and the superior mesenteric artery (66.7%). All prostheses were implanted successfully. No visceral arteries were lost. Of the 30 patients treated, 27 were available for 12-month follow-up and 23 were available for 24-month follow-up. No aneurysm-related deaths, aneurysm ruptures, or conversions were observed through 24 months of follow-up. No type I or type III endoleaks were observed. Type II endoleaks were noted in six (26.1%) at 12 months and four (20.0%) at 24 months. No patients had aneurysm growth >5 mm. Aneurysm size decreased in 16 of 23 (69.6%) and was stable in the remaining patients at 24 months. Eight patients experienced a renal event (4 renal artery stenoses, 2 renal artery occlusions, and 2 renal infarcts). Five underwent secondary interventions. No renal failure developed requiring dialysis. CONCLUSIONS The intermediate-term (24-month) results of the 30 patients in this multicenter study are concordant with previous single-center studies and support the concept that placement of fenestrated endovascular grafts is safe and effective at centers with experience in endovascular repair and renal/mesenteric stent placement.

Transfemoral endovascular aortic graft placement

PURPOSE The purpose of this study was to develop an endovascular system for transfemoral placement of straight aortic grafts and bifurcated aortoiliac grafts. METHODS Both types of graft consist of barbed, self-expanding stents attached to a woven polyester fabric. Survival studies of straight-graft function were performed in six large mongrel dogs. Digital subtraction fluoroscopic equipment was used to guide insertion and record angiograms at 0, 1, and 3 months. Bifurcated grafts were inserted in an additional eight dogs, four with distal stents and four without. Straight grafts were inserted into six cadaveric aortas (five atherosclerotic and one aneurysmal; age 68.7 + 5.7 years) to assess stent attachment. RESULTS Angiograms obtained immediately after straight-graft insertion showed placement to be within 4.6 + 1.6 mm of the intended level. Follow-up angiograms at 1 and 3 months showed no migration, no leakage, and patency of all six grafts. After bifurcated graft insertion there were no angiographic signs of perigraft leakage, with or without distal stents. The mean force required to displace straight grafts 10 mm from their original position in cadaveric aortas was 1388 + 127 g. CONCLUSION These preliminary results show that straight and bifurcated endovascular grafts can be positioned accurately and securely in the abdominal aorta.

Modular branched stent graft for endovascular repair of aortic arch aneurysm and dissection

PURPOSE We describe a modular stent graft for use in endovascular repair of aneurysms of the aortic arch. METHOD Carotid-carotid and left carotid-subclavian bypass grafts are created surgically. Two large, fully stented grafts are inserted endoluminally. The proximal component is bifurcated, with a wide proximal trunk and two distal limbs, one long and narrow, the other short and wide. This component is inserted through the carotid artery and deployed with the trunk and short wide limb in the ascending thoracic aorta; the long narrow limb opens into the innominate artery. After delivery system removal and carotid artery repair, a distal component is inserted through a femoral approach to bridge the gap between the short, wide distal limb of the proximal component and the nondilated descending thoracic aorta. The result is a branched stent graft, implanted proximally into the ascending aorta and distally into the innominate artery and descending thoracic aorta. CONCLUSION The system has been used successfully to treat a large wide-necked pseudoaneurysm of the aortic arch.

Clinical experience with a bifurcated endovascular graft for abdominal aortic aneurysm repair

PURPOSE The purpose of this study was to test a transfemoral system of bifurcated endovascular graft insertion for aortic aneurysm repair. METHODS Bifurcated endovascular grafts were inserted through bilateral femoral artery cutdowns in 41 patients. The results were assessed by completion angiography and follow-up computed tomography. RESULTS The second half of the study included more aneurysms 6 cm or larger (p < 0.05) and more instances of short proximal neck (p < 0.05), proximal neck angulation (p < 0.05), and iliac angulation (p < 0.05). Despite the increasingly challenging anatomy, the results were better in the second half of the study as illustrated by the lower overall combined morbidity/mortality rate (15% vs 50%) and higher overall success rate (85% versus 65%). The mortality rate for the series as a whole was 7.5%. Mean follow-up was 18.8 months for the first 20 patients and 10.9 months for the second 20. The commonest complication in the first half of the study was graft thrombosis (n = 5). This complication was absent from the second half of the study because of routine adjunctive stenting. Two patients died of complications of endovascular repair. In both cases aneurysm rupture on the third postoperative day was associated with coagulopathy and angiographic signs of perigraft leak. CONCLUSION Aneurysm exclusion with a bifurcated endovascular graft was feasible in a wide range of patients, but when the aneurysm was not entirely excluded from the circulation, the risk of rupture persisted.

Changing aneurysmal morphology after endovascular grafting: relation to leakage or persistent perfusion

PURPOSE To relate changing abdominal aortic aneurysm (AAA) morphology after endovascular grafting to the presence of leakage, collateral perfusion, and other factors. METHODS Thirty-five patients who underwent successful AAA endovascular grafting were evaluated. Self-expanding Z-stents and Dacron grafts were applied in bifurcated and aortomonoiliac systems. Postoperative diameter changes were calculated from repeated spiral computed tomographic scans, angiograms, and ultrasonic phase-locked echo-tracking scans during a median 6-month follow-up (interquartile range [IQR] 3 to 12). RESULTS At 12 months, the diameters of completely excluded aneurysms had decreased 6 mm (IQR 2 to 11; p = 0.006). The proximal graft-anchoring stents had dilated 2 mm (IQR 0.5 to 3.3; p = 0.01). The aortic diameters immediately below the renal arteries but above the stents had not changed. Endoleakage and collateral perfusion (n = 13) were each associated with preserved aneurysm size and a 12 times higher risk of aneurysm dilation. After the leakage or the collateral perfusion had been treated, the aneurysm size decreased. Aneurysms with extensive intraluminal thrombi presented a reduced risk of leakage or perfusion. CONCLUSIONS The diameters of endovascularly excluded AAAs decrease, except in cases of leakage or perfusion. Careful follow-up of patients with aortic endografts is necessary.

An Endovascular System for Thoracoabdominal Aortic Aneurysm Repair

Purpose: To describe a stent-graft system for endovascular repair of thoracoabdominal aortic aneurysm (TAAA) that preserves side branch perfusion. Technique: The modular endograft system includes 3 components. The primary stent-graft is custom-made from conventional graft fabric and Gianturco Z-stents. Covered nitinol Smart Stents are used for the visceral and renal extensions, and the distal extension is made from a modified Zenith system. With the supine patient under general anesthesia, the components are delivered sequentially through surgically exposed femoral and right brachial arteries in an operation that requires prolonged periods of magnified high-resolution imaging. This system was first used in a 76-year-old man with a contained rupture of a supraceliac ulcer and a large abdominal aortic aneurysm ending proximally at the celiac artery. The endograft was implanted successfully, but the patient developed paraplegia on day 2; imaging documented an excluded aneurysm and excellent flow through the endograft and all prosthetic branches. Discussion: Endovascular repair of TAAA appears to be feasible. If there are no serious, specific, unavoidable complications, the potential advantages are enormous.

Endoleakage after stent-graft treatment of abdominal aneurysm: Implications on pressure and imaging—an in vitro study

BACKGROUND Endoleakage is a fairly common problem after endovascular repair of abdominal aortic aneurysm and may prevent successful exclusion of the aneurysm. The consequences of endoleakage in terms of pressure in the aneurysmal sac are not exactly known. Moreover, the diagnosis of endoleakage is a problem because visualization of endoleaks can be difficult. METHOD With an ex vivo model of circulation with an artificial aneurysm managed by means of a tube graft, studies were performed to evaluate precisely known diameters of endoleaks with both imaging techniques (computed tomography and digital subtraction angiography) and pressure measurements of the aneurysmal sac. The experiments were performed without endoleak (controls) and with 1.231-French (0.410 mm), 3-French (1 mm), and 7-French (2.33 mm) endoleaks. Pressure and imaging were evaluated in the absence and presence of a simulated open lumbar artery. The pressure in the prosthesis and in the aneurysmal sac were recorded simultaneously. Digital subtraction angiography with and without a Lucite acrylic plate, computed tomographic angiography, and delayed computed tomographic angiography were performed. For the first experiments, the aneurysmal sac was filled with starch solution. All tests were repeated with fresh thrombus in the aneurysmal sac. RESULTS Each endoleak was associated with a diastolic pressure in the aneurysmal sac that was identical to diastolic systemic pressure, although the pressure curve was damped. At digital subtraction angiography without a Lucite acrylic plate, the 1.231-French (0.410 mm) endoleak was visualized without an open lumbar artery. When a Lucite acrylic plate was added, the endoleak was not visible until a lumbar artery was opened. In the presence of thrombus within the aneurysmal sac, all endoleaks were not visualized at digital subtraction angiography. At computed tomographic angiography, all endoleaks were not visualized in the absence of a thrombus mass in the aneurysmal sac. In the presence of thrombus within the aneurysmal sac, the 1.231-French (0.410 mm) endoleak became visible after opening of a simulated lumbar artery. At delayed computed tomographic angiography, all endoleaks were visualized without and with thrombus. CONCLUSION Every endoleak, even a very small one, caused pressure greater than systemic diastolic pressure within the aneurysmal sac. However, small endoleaks were not visualized with digital subtraction angiography and computed tomographic angiography, whereas all endoleaks were visualized with a delayed computed tomographic angiography protocol. We believe that follow-up examinations after stent graft placement for aortic aneurysms should focus on pressure measurements, but until this is clinically feasible, delayed computed tomographic angiography should be performed.

Early results of endovascular aortic aneurysm surgery with aortouniiliac graft, contralateral iliac occlusion, and femorofemoral bypass

PURPOSE The aim of this study was to evaluate the feasibility of endovascular aortic aneurysm repair with use of an aortouniiliac graft secured with self-expanding (Gianturco) stents. METHODS Thirty patients with a median age of 72 years (age range, 52 to 86 years) and aneurysm diameter of 6.0 cm (range, 4.0 to 9.0 cm) were treated with an aortouniiliac endovascular graft. Of these 30 procedures, 28 were carried out electively and two as emergencies for leaking aneurysm. Of the 30 patients, 21 (70%) were considered to be at high risk for open surgery. A modified Gianturco stent, Dacron graft, and Wallstent were used for these procedures. RESULTS Endovascular repair was successfully carried out in 25 of 30 (83.3%) patients. All these patients were mobile and had resumed a normal diet within 48 hours of the procedure. The overall 30-day mortality rate was two in 30 (6.6%), but it was one in 28 (3.5%) for the elective cases; all deaths occurred in the group at high risk for surgery. Other complications encountered within 30 days of procedure included myocardial infarction in one patient, pneumonia in two patients, homonymous quadrantanopia in one patient, and colonic ischemia in one patient, giving an overall morbidity rate of four in 30 (13.3%). At a median follow-up of 4 months (range, 1 to 13 months), 27 of 30 (90%) patients remain alive and well. CONCLUSION Endovascular aortouniiliac repair of abdominal aortic aneurysm with Gianturco stent is feasible in both elective and emergency situations. It appears to be minimally traumatic, and the majority of patients deemed to be at high risk for open surgery can safely undergo endovascular repair. However, data on more patients with longer follow-up is required to determine its role in the management of abdominal aortic aneurysm.

Endovascular aneurysm repair in high-risk patients☆☆☆★★★

PURPOSE The purpose of this study was to evaluate the role of endovascular aneurysm repair in high-risk patients. METHODS The elective endovascular repair of infrarenal aortic aneurysm was performed in 116 high-risk patients with either custom-made or commercial stent grafts. The routine follow-up examination included contrast-enhanced computed tomography (CT) before discharge, at 3, 6, and 12 months, and annually thereafter. Patients with endoleak on the initial CT underwent re-evaluation at 2 weeks. Those patients with positive CT results at 2 weeks underwent endovascular treatment. RESULTS Endovascular repair was considered feasible in 67% of the patients. The mean age was 75 years, and the mean aneurysm diameter was 6.3 cm. The American Society of Anesthesiologists grade was II in 3.4%, III in 65.5%, IV in 30.1%, and V in 0.9%. There were no conversions to open repair. Custom-made aortomonoiliac stent grafts were implanted in 77.6% of the cases, custom-made aortoaotic stent grafts in 11.2%, and commercial bifurcated stent grafts in 11.2%. The 30-day rates of mortality, major morbidity, and minor morbidity were 3.4%, 20.7%, and 12%, respectively, in the first 58 patients and 0%, 3.4%, and 3.4%, respectively, in the last 58. The late complications included five cases of stent graft kinking, two cases of femorofemoral graft occlusion, and three cases of proximal stent migration, one of which led to aneurysm rupture. At 2 weeks after repair, endoleak was present in 10.3% of the cases. All the type I (direct perigraft) endoleaks underwent successful endovascular treatment, whereas only one type II (collateral) endoleak responded to treatment. The technical success rate at 2 weeks was 86.2%, and the clinical success rate was 96.6%. The continuing success rate was 87.9%. Seventeen patients died late, unrelated deaths. CONCLUSION Endovascular aneurysm repair is safe and effective in patients at high risk, for whom it may be the preferred method of treatment.

Redefining postoperative surveillance after endovascular aneurysm repair: Recommendations based on 5-year follow-up in the US Zenith multicenter trial

INTRODUCTION Recommended postoperative surveillance after endovascular aneurysm repair (EVAR) includes serial contrast-enhanced CT scans. The cumulative deleterious effect on renal function, radiation exposure, and significant cost of this surveillance regimen are all problematic. However, there are scant data to support modulation of current post-EVAR surveillance regimens. METHODS The study comprised patients who underwent EVAR as part of the prospective multicenter pivotal (phase II) and continued-access (phase III) US Zenith Endovascular (Cook, Bloomington, Ind) graft trials. A core lab prospectively recorded patient data. A composite aneurysm-related morbidity (ARM) variable was calculated to include aneurysm rupture, open conversion, any secondary intervention, limb thrombosis, migration, renal morbidity, or aneurysm-related death. The long-term freedom from ARM as a function of the presence or cumulative absence of any endoleak at 1, 6, and 12 months was analyzed. The potential additive predictive utility of aneurysm sac shrinkage (>/=5 mm) was assessed at 12 months. The instructions for use for aortic neck anatomy (>/=15 mm length, 18 to 28 mm diameter, </=60 degrees angulation) were followed. RESULTS EVAR was done in 739 patients (mean follow-up, 29.9 +/- 17.1 months). Freedom from endoleak at 1 month was highly predictive (P < .001) of reduced ARM: freedom from ARM was 92.3%, 89.8%, 85.2%, 83.1% and 83.1 % at 1, 2, 3, 4, and 5 years, respectively, in patients without endoleak (83.1%) and 75%, 67.1%, 61.5%, 55.9%, and 55.9% in patients with endoleak (16.9%). Cumulative absence of endoleak at 1 year (77.6%) was associated with 94%, 91.5%, 88.1%, 85.8%, and 85.8% 1- to 5-year freedom from ARM vs 73.3%, 66.7%, 56.6%, 52.5%, and 52.5% in patients with endoleak </=1 year (22.4%), P < .001. In patients without endoleak at 12 months, the subsequent risk of any ARM was 8.2% (5-year risk, 14.2%; 1-year risk, 6.0%). In patients with significant sac shrinkage (>/=5 mm) and cumulative absence of endoleak at 12 months, the subsequent risk of an ARM was 5.3% (5-year risk, 11.1%; 1-year risk, 5.8%). CONCLUSIONS Absence of endoleak at 30 and 365 days predicted greatly improved long-term freedom from ARM compared with early endoleak. A new EVAR surveillance regimen is recommended that modulates the intensity and frequency of postoperative imaging based on these early outcomes. In patients without early endoleak, the 6-month surveillance is eliminated, and aortic ultrasound is suggested for long-term surveillance >1 year. In most patients, this reduced surveillance regimen would be appropriate and could improve patient safety by reducing the cumulative deleterious effects of intravenous contrast and radiation exposure while also reducing health care costs. These subjective recommendations would be ideally validated in a randomized, prospective trial.