Endovascular treatment of abdominal aortic aneurysm: a failed experiment.
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Aortic Aneurysm, Abdominal↗
Biomedical subjects
P W Wenham
Publications and source records attributed to P W Wenham.
Suitability for endovascular aneurysm repair in an unselected population (Br J Surg 2001; 88: 77-81).
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Angioscopy↗
Pathophysiology of proximal perigraft endoleak following endovascular repair of abdominal aortic aneurysms: a study using a flow model.
OBJECTIVE: to design a flow model to determine whether and why increased proximal neck angulation correlates with increased risk of proximal perigraft endoleak (PPE) flow. METHODS: a tapered stent-graft (Gianturco stent + Dacron) was deployed with proximal and distal necks made of silicone. The amount of PPE was measured over 30-s periods while the angulation of the proximal neck was increased. RESULTS: PPE flow increased significantly for angulations > or =30 degrees. The graft was lifted off the neck wall and gaps between the stent-graft and the neck created. CONCLUSION: greater neck angulation increased PPE flow. The stent-graft was lifted off the neck and subsequent gaps created. This model could be used to compare available stent-grafts and to test new designs that would improve the seal in angulated necks.
Anastomosis, Surgical↗
Endovascular repair of ruptured abdominal aortic aneurysm--a challenge to open repair? Results of a single centre experience in 20 patients.
INTRODUCTION: The mortality from ruptured abdominal aortic aneurysm (AAA) remains in the region of 50% despite advances in critical care. Endovascular repair of AAA has been shown to be associated with reduced physiological stress in the elective setting. It is hypothesised that the reduced physiological stress associated with EVAR may improve the outcome in patients with ruptured AAA. METHODS: A feasibility study of endovascular repair of ruptured AAA was undertaken at the University Hospital, Nottingham, U.K. between 1994 and 2000. Patients admitted with ruptured AAA were assessed by a team familiar with endovascular techniques for elective repair of AAA. After giving informed consent patients underwent spiral computed tomographic angiography (CTA) in the majority of cases. Patients were then transferred to the operating theatre for EVAR. RESULTS: Twenty patients underwent repair of ruptured AAA. Of these 20 patients, seven were referred from another hospital. Eight patients were considered unfit for open repair. The median duration of procedure was 180 min (range 120-480) and median blood loss was 1200 ml (range 750-2000 ml). The overall peri-operative mortality was 45%. A number of intra-operative and peri-operative procedures (both open and endovascular) were required to ensure aneurysm exclusion and to deal with the complications of endovascular surgery. CONCLUSIONS: Ruptured AAA remains a particularly hazardous condition to treat. There are a number of advantages of EVAR in this condition. A number of the problems early in the experience of EVAR have been addressed, but further experience is required to demonstrate its efficacy when compared with open repair.
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Incidence and treatment of intraoperative technical problems during endovascular repair of complex abdominal aortic aneurysms.
PURPOSE: The purpose of this study was to assess the incidence and management of intraoperative technical problems during endovascular repair (EVR) of complex abdominal aortic aneurysms (AAA). METHODS: From February 1995 to March 1999, 204 EVRs of nonruptured AAA were performed at our institution. One hundred seventy-six patients had an in-house custom-made graft; 172 were aorto-uni-iliac grafts, and four were aortoaortic grafts. Twenty- eight patients had a bifurcated graft. One hundred fourteen patients (56%) were high risk for conventional open repair. One hundred nine patients (53%) were not suitable for most commercially available devices. RESULTS: Intraoperative technical problems occurred in 81 patients (40%). There were 37 endoleaks (27 proximal, 10 distal), 15 graft stenoses, one failure of graft deployment, two graft thromboses, three aortoiliac ruptures, five renal artery occlusions (one bilateral, four unilateral), and 18 internal iliac occlusions (five bilateral, 13 unilateral). Endovascular management of these problems was successful in 37 of the 81 patients (46%) and included 15 balloon dilatations, 21 additional stent placements, and one graft thrombectomy. Fifteen of the 81 patients (19%) had open procedures (four periaortic ligature placements, six open aneurysm repairs, three common iliac ligations, and two extra-anatomic bypass grafts). In the remaining 29 patients, the on-table problem was managed expectantly. During follow-up, two of 37 patients (5%) who were treated successfully with endovascular procedures experienced recurrence. There were five deaths (33%) among the 15 patients who underwent open procedures. CONCLUSION: Intraoperative problems occur frequently during the endovascular management of complex aneurysms. Many of these problems can be managed with additional endovascular techniques without an increased risk of recurrence or procedure-related complications. Open procedures in high-risk patients carry a high mortality rate. The team performing EVR of AAA should be skillful in advanced endovascular and open surgical procedures.
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Sigmoid ischemia and the inflammatory response following endovascular abdominal aortic aneurysm repair.
PURPOSE: To assess the relationship between sigmoid colonic perfusion, endotoxemia, and cytokine generation in patients undergoing elective open repair (OR) or endovascular repair (EVR) of infrarenal abdominal aortic aneurysms (AAA). METHODS: Ten patients (9 males; average age 67.6 +/- 2.5 years, mean aneurysm diameter 6.9 +/- 0.6 cm) undergoing OR were compared to 10 patients (all males; average age 70.3 +/- 2.6 years, mean aneurysm diameter 6.5 +/- 0.5 cm) whose repair was performed using the EVR technique. The partial pressure of the carbon dioxide gap (PCO2gap = tissue PCO2 - arterial PCO2) of the sigmoid colonic mucosa was measured using a silicone tonometer to evaluate bowel perfusion. Blood samples were collected into pyrogen-free heparinized tubes for quantification of plasma concentrations of endotoxin, tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6) before, during, and after aortic repair. RESULTS: Patients in the OR group had a significantly greater increase in PCO2gap, suggesting a greater degree of bowel ischemia compared to the EVR group. This was associated with significantly greater postoperative concentrations of endotoxin, TNF-alpha, and IL-6 in the OR group. A significant correlation was found between PCO2gap, IL-6, and postoperative core temperature. CONCLUSIONS: The results suggest that the degree of bowel ischemia, endotoxemia, and cytokine generation following elective infrarenal AAA reconstruction may be reduced if the endovascular technique is used instead of conventional surgery.
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Prevention of side branch endoleaks with thrombogenic sponge: one-year follow-up.
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Aneurysm↗
Plasma endothelin levels in patients with abdominal aortic aneurysms.
OBJECTIVES: endothelin 1,2 plays a significant role in the process of atherogenesis and vascular wall injury. The aim of this study was to assess whether plasma endothelin 1,2 levels were elevated in patients with large or symptomatic abdominal aortic aneurysms (AAAs). DESIGN: a prospective open study. MATERIALS AND METHODS: plasma endothelin 1,2 levels were measured in 65 consecutive patients with infrarenal aortic aneurysms and compared with the levels in 44 healthy volunteer controls. The data for abdominal aneurysm patients was analysed in four subgroups: (i) small aneurysms (<5 cm), (ii) large aneurysms (>/=5 cm), (iii) asymptomatic aneurysms and (iv) symptomatic aneurysms. Comparisons were made between endothelin 1,2 levels in aneurysm patients and controls and between the different aneurysm subgroups. RESULTS: a highly significant difference (p<0.0001) was found between aneurysm patients and controls. Patients with large aneurysms had significantly higher levels than patients with small aneurysms (p<0.01). There was no statistical difference in endothelin 1,2 levels between symptomatic and asymptomatic patients; however, the highest levels were found in large, symptomatic aneurysms and the lowest in small, asymptomatic aneurysms. CONCLUSIONS: plasma endothelin 1,2 is an endogenous marker of aneurysm diameter. Further studies are required to determine whether it relates to the rate of growth of aneurysms.
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Mortality rates following endovascular repair of abdominal aortic aneurysms.
PURPOSE: To present the perioperative and late mortality following endovascular repair (EVR) of abdominal aortic aneurysms (AAAs). METHODS: Data were collected prospectively on 221 patients undergoing AAA EVR over a 4-year period (median 5-month follow-up). Patients were classified preoperatively as high risk with at least 1 of these features: serum creatinine > 150 micromol/L, ischemic heart disease or poor left ventricular function, respiratory function < 50% of predicted normal, ruptured or symptomatic AAA, contraindication to or failed open repair, and age > 80 years. RESULTS: One hundred forty (63.3%) patients were classified as high risk, the most common criterion being cardiac disease (n = 96, 68.6%). There were 25 (11.3%) deaths in the 30-day perioperative period, 22 (15.7%) in the high-risk group compared to 3 (3.7%) in the acceptable-risk group (p = 0.02). The most common causes of perioperative death were multisystem organ failure and myocardial infarction. A further 21 (9.5%) late deaths occurred, 16 (11.4%) in the high-risk group and 5 (6.2%) in the acceptable-risk group (p > 0.1). CONCLUSIONS: The mortality of patients at acceptable risk undergoing EVR compares with the best published series for conventional open AAA repair. The perioperative and late mortality in the high-risk patients are substantially higher.
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Early complications of femorofemoral crossover bypass grafts after aorta uni-iliac endovascular repair of abdominal aortic aneurysms.
OBJECTIVE: The following procedures are the 3 main methods of endovascular repair (EVR) of abdominal aortic aneurysms (AAA): aorto-aortic bypass grafting, bifurcated bypass grafting, and aorta uni-iliac grafts. The latter method has the potential disadvantage of requiring an extra anatomic graft (ie, a femorofemoral crossover bypass graft) to maintain contralateral pelvic and limb perfusion. The aim of this study was to assess the complications associated with the femorofemoral crossover bypass graft after aorta uni-iliac EVR of AAA. METHOD: A prospective review was conducted of the complications attributable to the femorofemoral crossover bypass graft in 136 patients who underwent EVR of AAA with an aorta uni-iliac device. RESULTS: During a median follow-up of 7 months (range, 0 to 36 months), 4 patients had superficial wound infections that required antibiotic treatment and 2 patients had bypass graft infections. Nine hematomas developed: 7 (5%) groin hematomas (6 in patients with Dacron bypass grafts), 1 scrotal hematoma, and 1 perigraft hematoma. One bypass graft thrombus developed. CONCLUSION: The femorofemoral crossover bypass graft is a safe and a durable component of EVR of AAA with an aorta uni-iliac device. The results are similar to those with bifurcated devices.
Aorta, Abdominal↗
Blood product requirements in patients undergoing elective endovascular abdominal aortic aneurysm repair.
OBJECTIVE: Endovascular repair (EVR) of abdominal aortic aneurysm (AAA) has many potential advantages, one of which may be reduced blood product requirements. The aim of this study was to compare the current blood product usage in our unit for three types of elective operation: EVR of AAA, open AAA repair and femorofemoral crossover grafts. DESIGN: Prospective data analysis with historical controls. MATERIALS: One-hundred and thirty-two patients undergoing elective EVR of AAA, 35 patients undergoing elective open repair of AAA and 37 patients having femorofemoral crossover grafts. METHODS: Data was collected on the blood product requirements of patients having EVR of AAA, with open AAA repair and femorofemoral crossover graft providing historical controls. RESULTS: There was no difference in the haematological parameters preoperatively between the three groups but postoperatively patients having EVR had a slightly lower haemoglobin than the open group (10.6 g/dl vs. 10.85 g/dl, p = 0.015). The number of patients who received blood transfusion in the EVR group was 82/132 (62%) and the open group 27/35 (77%), p = 0.4. CONCLUSION: Patients undergoing EVR of AAA require blood transfusion in the same numbers when compared to those undergoing open repair.
Aortic Aneurysm, Abdominal↗
Common iliac artery aneurysms in patients with abdominal aortic aneurysms.
OBJECTIVES: To determine the incidence of common iliac artery (CIA) aneurysms in patients with abdominal aortic aneurysms (AAA) and to evaluate the relationship between AAA and CIA diameter. METHODS: Spiral CT angiography was used to measure the maximum diameters of the abdominal aorta and the common iliac arteries of 215 patients with AAA. RESULTS: The median CIA diameter was 1.7 cm--significantly greater than the published mean of 1.25 (2 S.D. = 0.85-1.65) cm of an age-matched, non-vascular population. Thirty-four patients (16%) had unilateral and 26 patients (12%) bilateral CIA aneurysms > or = 2.4 cm diameter. Eight-six vessels (20%) were affected. Right CIA diameters were wider than left CIA diameters (p < 0.0001, Wilcoxon matched-pairs signed rank test). The correlation between AAA size and CIA diameter was weak. CONCLUSIONS: The AAA population has abnormally dilated common iliac arteries. In this population, common iliac artery aneurysms should be defined as those greater than 2.4 cm diameter. 20% of CIAs in patients with AAA are aneurysmal according to this definition.
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Thrombus distribution and changes in aneurysm size following endovascular aortic aneurysm repair.
OBJECTIVES: To determine (a) changes in aneurysm size following endovascular repair, (b) the significance of collateral lumbar artery blood flow and (c) the relationship between thrombus distribution within the aneurysm sac and the development of a "lumbar endoleak". MATERIALS AND METHODS: 72 patients treated with endovascular stent-grafts were followed up with spiral computed tomography for a median of 11 (range 3-27) months. The cross-sectional area of the aneurysm was measured at the point of maximum diameter pre- and post-operatively. The distribution and quantity of thrombus was recorded pre-operatively and this was related to changes in aneurysm size and the development of lumbar endoleaks post-operatively. RESULTS: An increase in aneurysm size occurred in 22 patients, of whom 10 had endoleaks. Fifteen aneurysms did not change in size, including four with endoleak, and 35 aneurysms decreased in size with no endoleaks. There was a significant difference between the endoleak and no endoleak groups (Chi-squared test = 17.1 with 2 degrees of freedom (d.f.), p < 0.001). Nine endoleaks were from patent lumbar arteries. No patients with thick circumferential or posteriorly placed thrombus developed an endoleak arising from lumbar vessels (0/23 cases) compared to those with minimal or anteriorly placed thrombus (9/49 cases) (Chi-squared test with Yate's correction = 3.17 with 1 d.f., p < 0.1). CONCLUSIONS: Aneurysms do not decrease in size in the presence of a lumbar endoleak, and some expand significantly. A number of aneurysms increase in size despite no evidence of an endoleak on computed tomography (CT). Patterns of thrombus distribution may be able to predict patients at risk from persistent endoleak via lumbar vessels.
Aortic Aneurysm, Abdominal↗
Spiral CT angiography versus aortography in the assessment of aortoiliac length in patients undergoing endovascular abdominal aortic aneurysm repair.
PURPOSE: To compare measurements of aortoiliac length obtained with spiral computed tomographic angiography (CTA) and aortography in patients undergoing endovascular aneurysm repair. METHODS: The distances from the lower-most renal artery to the aortic bifurcation and from the aortic bifurcation to the common iliac artery (CIA) bifurcation were measured using both CTA and aortography in 108 patients with abdominal aortic aneurysms. RESULTS: The level of agreement between CTA and aortography was high, with 69% of aortic and 76% of iliac measurements within 1 cm and > 90% within 2 cm of each other. Mean differences were -0.35 +/- 1.20 cm and 0.25 +/- 1.10 cm, respectively, for aortic and iliac lengths. Aortography overestimated renal artery to aortic bifurcation length in comparison to CTA (p = 0.003), particularly in patients with large aneurysms (> 6.5 cm) and lumen diameters > 4.5 cm (p < 0.0001). Measurements of CIA length were shorter by aortography than CTA (p = 0.02). CONCLUSIONS: There is a high level of agreement between CTA and aortography in the measurement of aortoiliac length, but aortography overestimates renal artery to aortic bifurcation length in patients with large-diameter aneurysms and wide aneurysm lumens. CTA is sufficiently accurate in the majority of cases to be used as the sole basis for the construction of endovascular grafts.
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Renal complications following endovascular repair of abdominal aortic aneurysms.
PURPOSE: To investigate the renal complications associated with endovascular repair of abdominal aortic aneurysms (AAAs). METHODS: Data were prospectively collected on 164 AAA patients (154 males; median age 72 years; interquartile range 51 to 88) undergoing endovascular grafting. Any history of renal failure and diabetes mellitus was recorded. Serum urea and creatinine levels were measured preoperatively and at regular intervals postoperatively. Renal impairment was defined as serum creatinine > 130 micromol/L. RESULTS: There were no significant differences in pre- and 1-day postoperative serum urea and creatinine levels. Among 15 (9.1%) patients with preoperative renal failure, 7 (47%) died, 4 (27%) in the perioperative period. Of the 149 patients with normal renal function preoperatively, 4 (2.7%) developed renal failure as part of multisystem organ failure. Another 9 (6.2%) developed significant postoperative elevations (> 20%) in their creatinine levels compared to baseline; 4 of these patients died, 2 in the perioperative period. There was no significant difference in the median dose of intravascular contrast used for those patients that did and did not have a deterioration in their renal function (250 mL versus 300 mL). CONCLUSIONS: In this study, approximately 6% of patients with normal preoperative renal function who undergo endovascular AAA repair develop renal dysfunction. For patients with preoperative renal impairment, the perioperative mortality rate is high, 27%, following endovascular aortic aneurysm repair.
Acute Kidney Injury↗
[Cytokine metabolism in aneurysms of the abdominal aorta].
The main cytokines which participate in the etiopathogenesis of aneurysms of the abdominal aorta (AAA) are: tumour necrotizing factor (TNF), interleukins 1b, 2, 6 and 8 (IL 1b, 2, 6, 8), platelet growth factor (PDGF) and endothelin 1, 2 (ET 1, 2). The objective of the presented work was to assess whether plasma levels of these cytokines can be used as endogenous markers of the size and symptomatology of AAA and also to what extent they correlated with hypertension which is a serious risk factor of AAA. During the three-year period (1995-1997) 86 patients with AAA were examined. The control group (n = 30) was formed by patients admitted for planned cholecystectomy. Plasma levels of all investigated cytokines with the exception of IL 8 in AAA differed markedly from the levels in the control group (p < 0.05-p < 0.0001). Changes in levels of IL8 and ET 1, 2 were significant in relation to the size of AAA (p < 0.05 and p < 0.01 resp.). The IL8 levels together with TNF in hypertonic patients correlated with the size of the AAA (p < 0.05 and p < 0.01 resp.), in normotonic subjects with the levels of IL 1b and IL2 (p < 0.05). The TNF levels were significant in symptomatic AAA (p < 0.05). The rising or declining levels of some plasma cytokines can serve as plasma markers of the growth and symptomatology of AAA.
Adult↗
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.
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The anatomy of abdominal aortic aneurysms: implications for sizing of endovascular grafts.
OBJECTIVE: To determine the full range of aorto-iliac anatomy of patients with abdominal aortic aneurysms (AAAs) and thence the range of endovascular graft sizes required to deal with the majority of AAAs. DESIGN: Analysis of preoperative spiral CT measurements. MATERIALS: One hundred and sixty-eight patients with AAAs. METHODS: Multiplanar reconstruction measurements were taken of proximal aortic neck diameter and length, lowermost renal artery to the aortic bifurcation distance and length and diameter of common iliac arteries. Based on these measurements a range of graft sizes that would fit the majority of AAAs was determined. RESULTS: Ranges of anatomical variables were as follows: proximal aortic neck diameter 18-30 mm, renal artery to aortic bifurcation distance 93-210 mm, common iliac artery length 13-108 mm, common iliac artery diameter 6-67 mm. Over 750 graft sizes would be required to cover all anatomical combinations using a one-piece aorto-uni-iliac graft. CONCLUSION: A wide variety of aorto-iliac anatomy exists in patients with AAAs. The large number of graft sizes required to deal with the majority of AAAs makes the production of one-piece endovascular grafts commercially impractical. A proposed two-piece modular graft would allow the majority of AAAs to be treated using only 16 graft sizes.
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