Abstract P6-10-04: “Disparities in breast cancer: A multi-institutional comparative analysis focusing on American Hispanics”

Background: Breast cancer (BC) is the leading cause of cancer death in Hispanic/Latina women nationwide. Hispanic women are more likely to be presented with advanced disease and might have adverse prognosis. Further, the Hispanics of Mexican-American origin might reflect different clinico-pathological characteristics as opposed to other Hispanics and ethnic groups. No previous largest studies comprised with Hispanics of Mexican-American origin explored tumor characteristics and compared to other ethnic groups. Thus, the aim of this study was to describe the clinico- pathological characteristics and disparities in breast cancer in this minority group at two tertiary care University- based medical centers in 2 states with a large Hispanic presence.

Methods: After IRB approval, cancer registry was used to analyze the variables of 3,441 patients with breast cancer diagnosed and treated consecutively at two large tertiary University based medical centers in El Paso, TX and Loma Linda, CA between 2005-2015. Unadjusted and adjusted associations of race/ethnicity with cancer stage, hormone receptor status and treatment option were investigated, as well as comparison to other ethnic groups.

Results: Overall 45.5% of the patients were Hispanic (n= 1566). Hispanics were more likely to be diagnosed at a younger age (57 years) compared to in non-Hispanic (NH) whites, more likely to have invasive ductal carcinoma type (82.7%) & triple negative disease (17.1%, 95%CI: 15% to 19%). 58.8% of Hispanics (95%CI: 56% to 61%) have HR+ & HER2- as opposed to 71% in NH whites. In addition, Hispanic individuals presented with advanced stages (III and IV) of BC (25.3%, 95% CI: 23% to 28%) similar to African Americans (25.4%), and had a lower proportion of lumpectomy versus mastectomy compared to NH whites (50%) but similar to African Americans (50%). Hispanic patients had the highest prevalence of triple negative BC (17.1% in Hispanics Versus 13.9 % in African Americans, versus 8.5% in NH whites). Hispanics also had significantly higher relative risk of HER2+/HR - disease (RRR=1.77, p<0.0001) compared to NH whites with no difference in African Americans (RRR= 1.21, p=0.56).

Conclusions: This large multi-institutional study shows that Hispanics are diagnosed with breast cancer at a younger age, have a higher prevalence of triple negative and HER2 positive/HR- breast cancer, are diagnosed at more advanced stages of disease and undergo less lumpectomies compared to NH whites. Increased efforts geared toward early detection, improving awareness and access to health care is desperately needed in this rapidly increasing minority in the U.S.

Citation Format: Otoukesh S, Nahleh Z, Mirshahidi HR, Nguyen AL, Botrus G, Badri N, Diab N, Alvarado A, Sanchez LA, Dwivedi A. “Disparities in breast cancer: A multi-institutional comparative analysis focusing on American Hispanics” [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-10-04.

Reproductive biology of Varroa destructor in Africanized honey bees (Apis mellifera)

Since its first contact with Apis mellifera, the population dynamics of the parasitic mite Varroa destructor varies from one region to another. In many regions of the world, apiculture has come to depend on the use of acaricides, because of the extensive damage caused by varroa to bee colonies. At present, the mite is considered to contribute to the recent decline of honey bee colonies in North America and Europe. Because in tropical climates worker brood rearing and varroa reproduction occurs all year round, it could be expected that here the impact of the parasite will be even more devastating. Yet, this has not been the case in tropical areas of South America. In Brazil, varroa was introduced more than 30 years ago and got established at low levels of infestation, without causing apparent damage to apiculture with Africanized honey bees (AHB). The tolerance of AHB to varroa is apparently attributable, at least in part, to resistance in the bees. The low fertility of this parasite in Africanized worker brood and the grooming and hygienic behavior of the bees are referred as important factors in keeping mite infestation low in the colonies. It has also been suggested that the type of mite influences the level of tolerance in a honey bee population. The Korea haplotype is predominant in unbalanced host-parasite systems, as exist in Europe, whereas in stable systems, as in Brazil, the Japan haplotype used to predominate. However, the patterns of varroa genetic variation have changed in Brazil. All recently sampled mites were of the Korea haplotype, regardless whether the mites had reproduced or not. The fertile mites on AHB in Brazil significantly increased from 56% in the 1980s to 86% in recent years. Nevertheless, despite the increased fertility, no increase in mite infestation rates in the colonies has been detected so far. A comprehensive literature review of varroa reproduction data, focusing on fertility and production of viable female mites, was conducted to provide insight into the Africanized bee host-parasite relationship.

Androgen excess in women: experience with over 1000 consecutive patients

The objective of the present study was to estimate the prevalence of the different pathological conditions causing clinically evident androgen excess and to document the degree of long-term success of suppressive and/or antiandrogen hormonal therapy in a large consecutive population of patients. All patients presenting for evaluation of symptoms potentially related to androgen excess between October 1987 and June 2002 were evaluated, and the data were maintained prospectively in a computerized database. For the assessment of therapeutic response, a retrospective review of the medical chart was performed, after the exclusion of those patients seeking fertility therapy only, or with inadequate follow-up or poor compliance. A total of 1281 consecutive patients were seen during the study period. Excluded from analysis were 408 patients in whom we were unable to evaluate hormonal status, determine ovulatory status, or find any evidence of androgen excess. In the remaining population of 873 patients, the unbiased prevalence of androgen-secreting neoplasms was 0.2%, 21-hydroxylase-deficient classic adrenal hyperplasia (CAH) was 0.6%, 21-hydroxylase-deficient nonclassic adrenal hyperplasia (NCAH) was 1.6%, hyperandrogenic insulin-resistant acanthosis nigricans (HAIRAN) syndrome was 3.1%, idiopathic hirsutism was 4.7%, and polycystic ovary syndrome (PCOS) was 82.0%. Fifty-nine (6.75%) patients had elevated androgen levels and hirsutism but normal ovulation. A total of 257 patients were included in the assessment of the response to hormonal therapy. The mean duration of follow-up was 33.5 months (range, 6-155). Hirsutism improved in 86%, menstrual dysfunction in 80%, acne in 81%, and hair loss in 33% of patients. The major side effects noted were irregular vaginal bleeding (16.1%), nausea (13.0%), and headaches (12.6%); only 36.6% of patients never complained of side effects. In this large study of consecutive patients presenting with clinically evident androgen excess, specific identifiable disorders (NCAH, CAH, HAIRAN syndrome, and androgen-secreting neoplasms) were observed in approximately 7% of subjects, whereas functional androgen excess, principally PCOS, was observed in the remainder. Hirsutism, menstrual dysfunction, or acne, but not alopecia, improved in the majority of patients treated with a combination suppressive therapy; although more than 60% experienced side effects.

Use of aortic cuffs to exclude iliac artery aneurysms during AneuRx stent-graft placement: initial experience

PURPOSE

As many as 39% of patients who undergo aortic endografting for abdominal aortic aneurysm disease will have ectasia of the iliac arteries that will require intervention. Coil embolization of the internal iliac artery and extension of the graft to the external iliac artery is one solution to this problem. However, 19%-41% of these patients experience buttock claudication, which may be permanent, after unilateral embolization. The authors examined an alternative: the use of larger-sized aortic cuffs to seal the iliac limb. Outcomes and short-term results are presented in this article.

MATERIALS AND METHODS

From October 1999 to August 2000, 144 AneuRx stent-grafts were placed at the authors' institution. Among the population receiving stent-grafts, 14 patients had 15 aortic cuffs placed across the distal iliac graft limbs to seal them and preserve flow to the internal iliac artery. One patient had bilateral cuffs placed. Five patients had embolization of the contralateral internal iliac artery because of bilateral disease. Patients were followed with computed tomography (CT) at 1, 6, and 12 months to evaluate for endoleaks.

RESULTS

One- and 6-month endoleak rates, determined from only those patients with follow-up CT, were 0% and 10%, respectively. One type II endoleak was first discovered 9 months after graft placement. It sealed spontaneously at 15-month follow-up. One patient among the five who had internal iliac artery embolization had claudication. Mean CT follow-up was 7.8 months (range, 1-15). One patient declined CT but was alive and well 11 months after endografting. One patient moved across the country and declined follow-up.

CONCLUSION

Placement of aortic cuffs in dilated iliac arteries can preserve flow to the ipsilateral internal iliac artery and provide an adequate seal. Additionally, the option of later treatment is maintained. Patients with bilateral iliac ectasia can undergo stent-graft placement without bilateral internal iliac artery embolization. Longer-term follow-up in larger numbers of patients will be important to determine the ultimate durability of this technique.

Endovascular abdominal aortic aneurysm repair in 144 patients: correlation of aneurysm size, proximal aortic neck length, and procedure-related complications

PURPOSE

During endovascular abdominal aortic aneurysm (AAA) repair, larger aneurysms often present formidable anatomic challenges to the insertion of the delivery catheter and graft deployment. The authors sought to evaluate whether large-diameter aneurysms and those with short proximal aortic necks might be associated with a higher frequency of insertion-related and short-term complications.

MATERIALS AND METHODS

From October 1999 to August 2000, 144 patients underwent elective endovascular graft placement for infrarenal AAA disease at the authors' institution. These patients were treated with use of the AneuRx bifurcated endoprosthesis. AAA size (maximum aneurysm diameter) and proximal aortic neck length were compared to estimated blood loss, operative time, accuracy of graft placement, presence of endoleak, intraoperative and postoperative complications (such as limb occlusion or vascular injury), length of hospital stay, and mortality. Statistical methods included correlation analysis and logistic regression.

RESULTS

There were 121 men and 23 women whose aneurysms ranged in size from 3 cm to 9.8 cm (mean, 5.6 cm; 95% CI, 5.4-5.8 cm). Endograft insertion was successful in all cases. There were three deaths within 30 days (2.1%) and seven deaths overall (4.9%). There were 43 intraoperative complications (29.9%) in 31 patients (21.5%), most of them minor. Patients with major intraoperative complications had significantly longer procedure times than those without complications (337 vs. 149 min; P <.0001). In the postoperative period (within 30 days), 31 complications (21.5%) occurred in 28 patients (19.4%), again most of them minor. AAA size was unrelated in any way to the rate of complications, but short proximal aortic neck length was associated with more serious intraoperative and postoperative complications (P =.0404 and P =.0230, respectively), and decreased 30-day and overall survival (P =.0240 and P =.0152, respectively).

CONCLUSIONS

Endovascular repair of large AAAs can be challenging; however, the size of the AAA does not influence the rate of complications. A short proximal aortic neck is the only significant risk factor for more serious complications.

Endoscopically assisted in situ lower extremity bypass graft: a preliminary report of a new minimally invasive technique

OBJECTIVE

Lower extremity arterial reconstructions with in situ greater saphenous vein (GSV) are an important component of limb salvage surgery. Initially, the procedure was performed through continuous skin incisions for side branch occlusion and valve lysis with a wound complication rate of 5% to 25%. To decrease these complications, we used endoscopic GSV harvest equipment in 25 in situ vein bypass grafts in 25 patients performed over 24 months.

METHODS

The procedures were performed with three skin incisions: two for arterial access and a 2-cm incision above the knee to insert the Endopath device (Ethicon) to locate and clip the GSV side branches. After completion of the proximal anastomosis, the valves were lysed through the distal end of the vein with a flexible valvulotome. Completion cineangiography was performed to confirm side branch occlusion and evaluate the entire reconstruction. The results of this technique were compared with our last 25 in situ bypass grafts done with standard long incisions.

RESULTS

In the endoscopic group there was one (4%) minor wound complication (cellulitis). No postoperative arteriovenous fistulas were detected by means of duplex examination, and the average hospital stay was 6.2 +/- 1 days. One graft closed at 9 months as a result of distal vein hyperplasia, but the other grafts have remained patent, with follow-up from 6 to 30 months (mean, 18 months). Patients with the standard in situ bypass grafts had significantly (P < .05) more wound complications (20%) and longer average hospital stay (9.2 +/- 2 days) than the endoscopic group. Patency rates were comparable for both groups.

CONCLUSION

These results show that less invasive endoscopic in situ bypass grafting minimizes wound complications and reduces the need for hospitalization without decreasing patency or increasing operative time.

Endoluminal graft repair for abdominal aortic aneurysms in high-risk patients and octogenarians: is it better than open repair?

OBJECTIVE

To analyze the short-term and midterm results of open and endoluminal repair of abdominal aortic aneurysms (AAA) in a large single-center series and specifically in octogenarians.

METHODS

Between January 1997 and October 2000, 470 consecutive patients underwent elective repair of AAA. Conventional open repair (COR) was performed in 210 patients and endoluminal graft (ELG) repair in 260 patients. Ninety of the patients were 80 years of age or older; of these, 38 underwent COR and 52 ELG repair.

RESULTS

Patient characteristics and risk factors were similar for both the entire series and the subgroup of patients 80 years or older. The overall complication rate was reduced by 70% or more in the ELG versus the COR groups. The postoperative death rate was similar for the COR and ELG groups in the entire series and lower (but not significantly) in the ELG 80 years or older subgroup versus the COR group. The 36-month rates of freedom from endoleaks, surgical conversion, and secondary intervention were 81%, 98.2%, and 88%, respectively.

CONCLUSION

The short-term and midterm results of AAA repair by COR or ELG are similar. The death rate associated with this new technique is low and comparable, whereas the complication rate associated with COR in all patients and those 80 years or older in particular is greater and more serious than ELG repair. Long-term results will establish the role of ELG repair of AAA, especially in elderly and high-risk patients.

Evolution of vascular fellowship training in the new era of endovascular techniques

PURPOSE

The endovascular technique has revolutionized the treatment of infrarenal abdominal aortic aneurysm (AAA). At our institution, we examined the impact of an endovascular program on the traditional operative training of the vascular fellows in the treatment of infrarenal AAA.

METHODS

We examined the records of our vascular fellows' experience from July 1995 to May 2000. We introduced the endovascular treatment for infrarenal AAA in 1995.

RESULTS

The fellows have performed increasing numbers of endovascular cases each year, with a predicted number of 124 cases for 1999-2000. However, despite an increase in the overall volume of patients with infrarenal AAA (102 cases in 1998-1999 and a predicted 160 cases in 1999-2000), the trainees will experience a reduction in the number of open AAAs from 61 cases in 1998-1999 to a predicted 36 cases in 1999-2000. However, the volume of open suprarenal AAA has also increased from eight cases in 1998 to 1999 to a predicted 24 cases in 1999-2000. With no significant change in the open aortoiliac occlusive cases from previous years, the current fellows will graduate with a similar volume of open aortic procedures as their predecessors.

CONCLUSION

With the recent advances in endovascular technology, our traditional operative approach to the treatment of AAA disease may be lacking in the training of future vascular surgeons. At our institution, although fewer open infrarenal AAA cases were performed, the trainees have maintained the open aortic experience by performing an increased volume of suprarenal AAAs. We have to critically reevaluate and redefine what constitutes adequate vascular fellow experience in the surgical treatment of abdominal aortic aneurysms.

Stratified administration of serotonin 5-HT3 receptor antagonists (setrons) for chemotherapy-induced emesis. Economic implications

The serotonin 5-HT3 receptor antagonists or 'setrons' have become the standard of care for the prevention of chemotherapy-induced emesis (CIE) and are first-line therapy for acute CIE in healthcare organisations worldwide. However, their superior efficacy versus standard antiemetics comes at a significant cost. Currently, 3 agents are available in the US: ondansetron, granisetron and dolasetron. The most important treatment-related factor contributing to CIE is the emetogenicity of chemotherapy. The ability to customise, or stratify, the setron dose to match the emetogenic challenge of the chemotherapy administered has potential benefits, both clinically and economically. In adults, there is an appreciable amount of clinical literature addressing stratified administration; however, the amount of 'hard' economic data is rather limited. Intuitively, if clinical outcomes are equivalent, then stratified administration should be associated with economic benefits, as it generally promotes the use of doses lower than those recommended by the manufacturer. The literature strongly substantiates this for ondansetron, but is not as favourable for granisetron or dolasetron. As the rationale and justification for dose stratification is contained in the clinical literature, the authors have reviewed the pertinent literature supporting the clinical and economic benefits of dose stratification in both adult and paediatric patients. The authors also provide a discussion of various additional strategies that can be employed to ensure the appropriate and cost-effective use of setrons in real-world practice settings. These strategies include the use of lower doses than recommended by manufacturers, use for acute versus delayed phase emesis, enhancing the antiemetic efficacy by the addition of a corticosteroid, use of oral versus injectable formulations (when appropriate) and the implementation and use of local, national and international drug use guidelines.

Applied pharmacoeconomics: modeling data from internal and external sources

The use and application of techniques for modeling data obtained from various data sources are discussed. Modeling with internal and external data has become a popular way for health care organizations to apply pharmacoeconomics to pharmacy practice. Modeling studies use existing clinical and epidemiologic data to project the effect of a clinical, policy, or medication decision on a patient, population, or organization. Although several modeling techniques have been used in health care, the most common approaches are to modify and adapt existing models or to develop a unique model to answer questions of interest in a specific practice setting. Typically, an economic model developed by adapting an existing one will use either the clinical decision-analysis or Markov modeling technique. Regardless of the technique used, external data must be carefully evaluated to ensure that the data are appropriate for use in making decisions at a specific organization. For example, cost data must be analyzed to ensure that the calculations are reproducible. Also, it must be acknowledged that this strategy may not always be appropriate. The use of modeling techniques can assist decision-makers in making more informed clinical, policy, and medication decisions in real-world settings. Caution is required when adapting and interpreting existing models to ensure appropriate application in a specific organization.

Can a tissue-engineered skin graft improve healing of lower extremity foot wounds after revascularization?

A bilayered tissue-engineered skin graft composed of human neonatal foreskin fibroblasts and keratinocytes in a type I bovine collagen matrix has been developed. We sought to determine if this graft improves wound healing after lower extremity revascularization. Thirty-one previously ischemic foot wounds were randomly assigned to moist dressing changes or tissue-engineered skin graft within 60 days of revascularization. In the grafted group, 10 received meshed and 11 received unmeshed graft. Wound healing was followed by wound area measurements and photography. There were no statistically significant differences between groups in patient age, sex, diabetes or renal failure risk factors, revascularization procedure, or wound location or size. Treatment with tissue-engineered skin graft was significantly more effective than moist dressing in the percentage of wounds healed (62 vs. 0% at 8 weeks, 86 vs. 40% at 12 weeks, p < 0.01) and the median time to complete wound closure (7 vs. 15 weeks, p = 0.0021, rank-sum test). There was no difference in the wound closure rate of meshed and unmeshed graft at 4, 8, 12, or 24 weeks (p > 0.05). Three indolent localized wound infections in the tissue-engineered skin graft group were the only complication. Tissue-engineered skin grafting can be used safely in previously ischemic wounds after lower extremity revascularization. Treatment with this graft promotes healing more rapidly and in more patients than standard moist dressings. It obviates the risk, inconvenience, and expense of donor skin harvesting, anesthesia, and hospitalization associated with autologous skin grafting. This graft may represent an advance in the treatment of previously ischemic lower extremity foot wounds.

Repair of bilateral common iliac artery aneurysms coexisting with a pelvic horseshoe kidney

This report describes the treatment of bilateral common iliac artery aneurysms in a patient with a pelvic horseshoe kidney. Anomalous renal arteries arising from the aorta, the common iliac arteries, and the left hypogastric artery were identified precisely by selective angiography. These multiple renal artery anomalies and the presence of a large pelvic horseshoe kidney complicated the surgical treatment of the aneurysms. The repair of the aneurysms was successfully accomplished by staged retroperitoneal procedures. This technique allowed excellent visualization of the iliac aneurysms and preservation of all renal arteries with intact renal function.

Midterm experience with the endovascular treatment of isolated iliac aneurysms

PURPOSE

This report describes our 5-year experience with the endovascular repair of isolated iliac aneurysms and pseudoaneurysms.

METHODS

Between June 1993 and July 1998, 40 isolated iliac aneurysms and pseudoaneurysms were treated with endovascular grafts in 39 patients. Thirty-seven aneurysms were treated with endovascular grafts composed of polytetrafluoroethylene grafts and balloon expandable stents, and the other three underwent repair with a polycarbonate urethane endoluminal graft.

RESULTS

All the patients underwent initially successful endovascular treatment of isolated iliac aneurysms and pseudoaneurysms and were followed from 1 to 51 months (mean, 18 months). The 4-year primary patency rate was 94.5% +/- 10%. The perioperative complications included one episode of distal embolization, an episode of colonic ischemia, five episodes of kinking or compression of the endovascular graft, and one early postoperative graft thrombosis. There was only one perioperative death in a patient whose aneurysm ruptured in the operating room just before endovascular repair. The median postoperative length of hospital stay was 3.0 +/- 1.3 days in this group of patients at moderate and high risk. The long-term complications included one graft thrombosis and two endoleaks. One small endoleak was followed until the patient died of unrelated causes, and the other one led to aneurysm rupture in the only patient temporarily lost to follow-up examination. This patient successfully underwent treatment in the standard open surgical fashion. To date, all the other aneurysms have remained stable or have decreased in size during the follow-up examinations with duplex or contrast-enhanced computed tomographic scans.

CONCLUSION

Endovascular repair of iliac aneurysms and pseudoaneurysms is a safe and effective technique with good midterm results in patients at standard and high risk. These grafts are particularly beneficial for patients with medical, surgical, or anatomic contraindications for open surgical repair.

Applied pharmacoeconomics: evaluation and use of pharmacoeconomic data from the literature

The evaluation and use of published pharmacoeconomic data are discussed. The pharmacoeconomic literature is a vast and powerful source of information for pharmacists and others who must make decisions about services and products. Published studies can provide data quickly and inexpensively, but they may not necessarily meet criteria for quality and may not be generalizable to a specific situation. Guidelines are available that are intended to standardize study methods, minimize potential bias, and increase the comparability and credibility of data. Before relying on a published study, decision-makers should ensure that it meets criteria related to objective, perspective, pharmacoeconomic method, design, interventions, costs, outcomes, discounting, results, sensitivity analysis, extrapolation of conclusions, and sponsorship. A sound study can be used to support decisions in such diverse areas as individual patient treatment, formulary management, drug-use guideline development, disease management initiatives, and pharmaceutical service evaluation. A decision-maker may be able to use the results by applying them at face value, employing a sensitivity analysis, performing a meta-analysis, incorporating the data into a pharmacoeconomic model, or reproducing the study on a smaller scale. The selection of an application strategy should be based on the potential impact of the decision on the quality and cost of care, with more rigorous and complex strategies reserved for more extreme impacts. Published pharmacoeconomic data can help pharmacists make better and more informed decisions about pharmaceutical services and products.

When is urokinase treatment an effective sole or adjunctive treatment for acute limb ischemia secondary to native artery occlusion?

BACKGROUND

Intra-arterial thrombolytic therapy is currently a therapeutic option for the treatment of acute limb ischemia. A recent large prospective randomized trial (TOPAS) comparing lytic therapy and operative intervention showed that both forms of treatment had similar results in terms of amputation-free survival. However, the exact role for lytic treatment is unclear.

METHOD

Over a 4-year period we treated 60 cases of acute limb ischemia in 57 patients secondary to native artery occlusion with thrombolytic therapy with urokinase. All patients were evaluated at 1 week, 1 month, and then at 3-month intervals posttreatment. Follow-up evaluations included pulse examination, pulse volume recordings, and duplex examinations to confirm arterial patency. No patients were lost to follow-up with a range of 8 to 54 months (mean 26).

RESULTS

Of these 60 native arterial occlusions, complete lysis was achieved in 46 cases (76%). Of these 46 cases, 18 required lysis only, 19 cases (9 iliac, 7 superficial femoral artery (SFA), and 3 popliteal) required angioplasty of lesions uncovered by clot lysis, and 9 patients had lysis and angioplasty of iliac arteries followed by infrainguinal bypasses. Eight of the 57 patients (14%) who had been asymptomatic presented with symptoms limited to new onset claudication, all of which were successfully lysed. Cumulative patency for the 43 successful cases was 90% +/- 5% at 1 year and 75% +/- 4% at 2 years. The 1-year amputation-free survival for all native artery occlusions was 85% +/- 6%.

CONCLUSION

Thrombolysis with urokinase simplified the treatment of native arterial occlusion proving to be the sole therapy in 18 (29%) patients or a valuable adjunct by facilitating the angioplasty of arterial lesions and avoiding open surgery in 60% of patients treated. In addition, the correction of inflow lesions reduced the magnitude of required subsequent bypass procedures to achieve limb salvage. In conclusion, successful thrombolysis of native artery occlusion provided durable arterial patency and limb salvage, particularly in patients with new onset claudication.

Analysis of endovascular graft treatment for aortoiliac occlusive disease: what is its role based on midterm results?

OBJECTIVE

To analyze the authors' midterm results (up to 4 years) using endovascular grafts to treat aortoiliac occlusive disease in patients with limb-threatening ischemia.

SUMMARY BACKGROUND DATA

Endovascular grafts are being used to manage some aortoiliac lesions formerly treated by aortofemoral or extraanatomic bypass grafts. However, widespread acceptance of these new grafts depends on their late patency and clinical utility.

METHODS

Between January 1993 and December 1997, 52 patients with aortoiliac occlusive disease were treated with endovascular grafts. The primary indication for treatment was gangrene or ulceration in 42 patients (81%) and rest pain in 10 patients (19%). Sixteen patients had symptomatic contralateral limbs that were also treated, and 27 (52%) patients required a synchronous infrainguinal bypass. Results up to 4 years were evaluated by life table analysis.

RESULTS

Forty-six (88%) of the patients had complete follow-up of 3 to 57 months (median 22 months). Six patients were lost to follow-up at a mean of 20 months after surgery. The 4-year primary and secondary patency rates for the endovascular grafts were 66.1% and 72.3% respectively. Six patients required a major amputation, and the limb salvage rate was 88.7%. Four-year patient survival was 37%, with 23 patients dying during this follow-up period.

CONCLUSIONS

Endovascular grafts can often be used when conventional procedures are contraindicated or technically impractical. These grafts are a valuable alternative to extraanatomic and aortofemoral bypasses in high-risk patients with aortoiliac occlusive disease and critical ischemia.

Endovascular graft repair of ruptured aortoiliac aneurysms

BACKGROUND

The feasibility of endovascular graft (EVG) repair of ruptured aortoiliac aneurysms (AIAs) has yet to be demonstrated. There are inherent limitations in EVG repair, including the need for preoperative measurements of the aneurysmal and adjacent arterial anatomy to determine the appropriate size and type of graft and the inherent delay to obtain proximal occlusion. We developed an EVG system with broad versatility that largely eliminates these problems.

STUDY DESIGN

Between 1993 and 1998, within an experience of 134 endovascular AIA repairs, 12 ruptured AIAs were treated using EVGs that facilitated intraoperative customization and eliminated the need for preoperative measurements. The EVGs consisted of either a Palmaz stent and a PTFE graft deployed by a compliant balloon (n = 9) or a self-expanding covered stent graft (n = 3). Both grafts were cut to the appropriate length intraoperatively. The mean age of the patients was 72 years (range 40 to 86 years). The mean size of the aneurysms was 7.6 cm (range 3 to 16 cm). Preoperative symptoms were present in all patients and included abdominal or back pain (n = 9), syncope (n = 4), and external bleeding (n = 2). All patients were high surgical risks because of comorbid disease (n = 10) or previous abdominal operations (n = 6), and nine experienced hypotension.

RESULTS

All EVGs were inserted successfully and excluded the aneurysms from the circulation. The mean operating time was 263 minutes, the mean blood loss was 715 mL, and the mean length of hospital stay was 6.5 days. There were two deaths (16%), one from the preexisting acute myocardial infarction and one from multiple organ failure. There were three minor complications (25%). Two patients required evacuation of an intraabdominal hematoma from the initial rupture. All but one of the grafts was functioning at a mean followup of 18 months.

CONCLUSIONS

This study demonstrates the feasibility of EVG repair for ruptured AIAs using a graft that can be customized intraoperatively for each patient. Such repairs currently are valuable in patients with ruptured AIAs and serious comorbidities and may be applicable in other circumstances as well.

Diagnosis and treatment of chronic lower extremity ischemia

Chronic lower extremity ischemia is due to progressive atherosclerosis of the aorto-iliac and/or infrainguinal arteries. This disease process is of great importance as millions of patients are affected by lower extremity arterial occlusive disease. Most of these patients are asymptomatic but a growing number of them are symptomatic, with complaints ranging from mild claudication to gangrene. The increasing number of patients affected by lower extremity atherosclerosis is, in part, due to the 'graying' of the general population and to the medical improvements of the past three decades that have allowed patients with generalized atherosclerosis to survive longer. Fortunately, the diagnosis and management of peripheral arterial occlusive disease has also significantly progressed leading to improved graft patency, limb salvage rates, and quality of life for patients.

Early experience with the Corvita endoluminal graft for treatment of arterial injuries

The aim of this study was to evaluate our early experience with the Corvita endoluminal graft for the treatment of a variety of arterial injuries. Ten patients with arterial pseudoaneurysms (8) or arteriovenous fistulas (2) due to arterial injuries were followed prospectively after undergoing treatment with the endovascular graft. Our results showed that the Corvita low-profile endoluminal graft can be successfully used to treat arterial injuries but that it sometimes requires the placement of additional stents in patients with tortuous or tapering vessels. These grafts are extremely useful for the safe treatment of difficult and high-risk patients. Further improvements in available endovascular grafts and good long-term results will be necessary before considering these grafts the best treatment available for most patients with significant arterial injuries.

Can duplex scan arterial mapping replace contrast arteriography as the test of choice before infrainguinal revascularization?

PURPOSE

Arteriography is the diagnostic test of choice before lower extremity revascularization, because it is a means of pinpointing stenotic or occluded arteries and defining optimal sites for the origin and termination of bypass grafts. We evaluated whether a duplex ultrasound scan, used as an alternative to arteriography, could be used as a means of accurately predicting the proximal and distal anastomotic sites in patients requiring peripheral bypass grafts and, therefore, replace standard preoperative arteriography.

METHODS

Forty-one patients who required infrainguinal bypass grafts underwent preoperative duplex arterial mapping (DAM). Based on these studies, an observer blinded to the operation performed predicted what operation the patient required and the best site for the proximal and distal anastomoses. These predictions were compared with the actual anastomotic sites chosen by the surgeon.

RESULTS

Whether a femoropopliteal or an infrapopliteal bypass graft was required was predicted correctly by means of DAM in 37 patients (90%). In addition, both anastomotic sites in 18 of 20 patients (90%) who had femoropopliteal bypass grafts and 5 of 21 patients (24%) who had infrapopliteal procedures were correctly predicted by means of DAM.

CONCLUSION

DAM is a reliable means of predicting whether patients will require femoropopliteal or infrapopliteal bypass grafts, and, when a patient requires a femoropopliteal bypass graft, the actual location of both anastomoses can also be accurately predicted. Therefore, DAM appears able to replace conventional preoperative arteriography in most patients found to require femoropopliteal reconstruction. Patients who are predicted by means of DAM to require crural or pedal bypass grafts should still undergo preoperative contrast studies to confirm these results and to more precisely locate the anastomotic sites.

Percutaneous transluminal angioplasty for the treatment of limb threatening ischemia: do the results justify an attempt before bypass grafting?

PURPOSE

Results of percutaneous transluminal angioplasty (PTA) in selected cases have been reported to be equal or superior to those of arterial bypass graft surgery, with a lower morbidity and mortality. We performed PTA of stenotic or occlusive lesions in patients with limb-threatening ischemia, hoping to improve our overall success and decrease morbidity in this group of patients. The results of PTA in the limb-salvage setting was evaluated.

METHODS

From 1992 to 1995, 307 PTAs were performed in 257 patients. One hundred sixty-one (63%) patients had diabetes mellitus, and 32 (12%) patients had renal failure. All patients were evaluated by means of pulse volume recordings and ankle brachial indices at 1 and 6 weeks after PTA and at 3 month intervals thereafter. Seventeen patients (9%) were lost to follow-up. The continued success or failure of PTA was defined by means of noninvasive vascular laboratory criteria, patency by means of pulse examination, the need for subsequent bypass grafting across the index lesion, and limb salvage.

RESULTS

The 1-year patency rates for external iliac PTAs (56%) were significantly lower (P <.05) than those for common iliac PTAs (87%). Infrainguinal PTAs at the femoral, popliteal, and tibial level had 1-year patency rates of less than 15%.

CONCLUSION

Common iliac artery PTA is justified in most cases in which it is feasible. However, when PTAs are performed below the inguinal ligament, the results are markedly worse. One-year patency rates of PTA in this group of patients with threatened limbs are inferior to the patency rates of arterial bypass grafts, even when these bypasses are performed with a prosthetic material. PTA should not be considered as a primary treatment modality for patients with infrainguinal arterial occlusive disease who also have limb-threatening ischemia, except in unusual circumstances.

Endovascular treatment of a ruptured lumbar artery aneurysm: case report and review of the literature

Lumbar artery aneurysms are uncommon lesions that usually present as pseudoaneurysms secondary to vessel injury. Despite their small size and retroperitoneal location, these lesions are potentially lethal once they rupture. This report describes a ruptured lumbar artery aneurysm which was successfully treated in a minimally invasive fashion. The diagnosis was suggested by computed tomography scan and confirmed with angiography. Successful treatment consisted of placing intravascular metallic coils into the lumbar artery. The literature contains only seven previous reports of ruptured lumbar artery aneurysms and these were managed either operatively or via an endovascular approach. Based upon the outcome of all reported cases, we believe that coil embolization of lumbar artery aneurysms following diagnostic angiography is an appropriate and effective mean of treating these lesions.

Endovascular therapy for upper extremity injury

Various endovascular techniques, including the placement of embolization coils, intravascular stents, and the use of stented grafts, have been used in the setting of traumatic upper extremity injuries. Coil embolization and stent placement are effective in a limited number of cases. Endovascular grafts have greatly extended the potential of endovascular therapy for upper extremity vascular trauma. The ideal graft material, stent, and the best mechanism for stent deployment have not been determined. In addition, long-term effectiveness of such therapy is yet to be shown. Nevertheless, endovascular grafts offer distinctive advantages in some cases and are important tools for the treatment of vascular trauma and should be included in the armamentarium of all vascular surgeons.

Value of CT angiography for postoperative assessment of patients with iliac artery aneurysms who have received endovascular grafts

OBJECTIVE

The purpose of the study was to assess the usefulness of CT angiography for follow-up of patients with iliac artery aneurysms who have undergone endovascular treatment.

SUBJECTS AND METHODS

Twelve patients with iliac artery aneurysms (10 true aneurysms and two pseudoaneurysms) were examined with CT angiography within 1 week of receiving transfemorally placed endovascular grafts. All patients underwent follow-up CT angiography from 3 to 30 months (mean, 11 months) later. Follow-up CT angiography at 6 months or later (mean, 14 months) was also available in 10 patients. All studies were obtained after i.v. contrast administration using 3-mm collimation, 1.6-2.0 pitch, 2-mm retrospective reconstruction, and with subsequent three-dimensional rendering and multiplanar reformation. The shape and patency of the graft, perigraft thrombosis, and the size of the aneurysm were assessed.

RESULTS

All grafts remained patent and without deformity. Complete thrombosis of the aneurysm was shown by initial postoperative CT angiography in 11 patients and confirmed by follow-up studies. A single case of a perigraft leak was revealed by CT angiography and confirmed by follow-up angiography. No aneurysm showed change in size at late follow-up.

CONCLUSION

CT angiography is an accurate method for evaluating endovascular devices. CT angiography can be used as a primary technique for follow-up of patients who have undergone endovascular repair of iliac aneurysms.

Ex vivo human carotid artery bifurcation stenting: correlation of lesion characteristics with embolic potential

PURPOSE

To develop an ex vivo human carotid artery stenting model that can be used for the quantitative analysis of risk for embolization associated with balloon angioplasty and stenting and to correlate this risk with lesion characteristics to define lesions suitable for balloon angioplasty and stenting.

METHODS

Specimens of carotid plaque (n = 24) were obtained circumferentially intact from patients undergoing standard carotid endarterectomy. Carotid lesions were prospectively characterized on the basis of angiographic and duplex findings before endarterectomy and clinical findings. Specimens were encased in a polytetrafluoroethylene wrap and mounted in a flow chamber that allowed access for endovascular procedures and observations. Balloon angioplasty and stenting were performed under fluoroscopic guidance with either a Palmaz stent or a Wallstent endoprosthesis. Ex vivo angiograms were obtained before and after intervention. Effluent from each specimen was filtered for released embolic particles, which were microscopically examined, counted, and correlated with various plaque characteristics by means of multivariate analysis.

RESULTS

Balloon angioplasty and stenting produced embolic particles that consisted of atherosclerotic debris, organized thrombus, and calcified material. The number of embolic particles detected after balloon angioplasty and stenting was not related to preoperative symptoms, sex, plaque ulceration or calcification, or artery size. However, echolucent plaques generated a higher number of particles compared with echogenic plaques (p < 0.01). In addition, increased lesion stenosis also significantly correlated with the total number of particles produced by balloon angioplasty and stenting (r = 0.55). Multivariate analysis revealed that these two characteristics were independent risk factors.

CONCLUSIONS

Echolucent plaques and plaques with stenosis > or = 90% produced a higher number of embolic particles and therefore may be less suitable for balloon angioplasty and stenting. This ex vivo model can be used to identify high-risk lesions for balloon angioplasty and stenting and can aid in the evaluation of new devices being considered for carotid balloon angioplasty and stenting.

Technique for obtaining proximal intraluminal control when arteries are inaccessible or unclampable because of disease or calcification

When proximal arterial control cannot be obtained by standard methods, it may be achieved safely and bloodlessly by intraluminal routes with balloon catheters, hemostatic sheaths, and catheter-guide wire techniques. This method was used successfully in 20 patients to achieve proximal arterial control without complications in a variety of locations. Use of this method or its modifications may facilitate and simplify a variety of vascular operations that would otherwise be difficult or hazardous.

Endoleak after endovascular graft repair of experimental aortic aneurysms: does coil embolization with angiographic "seal" lower intraaneurysmal pressure?

PURPOSE

To investigate the relation between endoleaks and intraaneurysmal pressure (IAP) and the effect of coil embolization in the management of endoleaks.

METHODS

The infrarenal aorta of a dog (n = 15) was replaced by a polytetrafluoroethylene aneurysm containing a pressure transducer. Group I (n = 4) had untreated aneurysms. Group II (n = 4) had endovascularly excluded aneurysms without an endoleak. Group III (n = 7) had aneurysms excluded by means of grafts with a defect that represented the source of an endoleak. After 4 weeks of follow-up study, the endoleaks in group III dogs were subjected to coil embolization. Systolic IAP was measured daily and expressed as a ratio of systolic blood pressure obtained from a forelimb cuff. Arteriography, duplex ultrasonography, and spiral contrast computed tomography were performed to evaluate endoleaks.

RESULTS

In group I, the LAP remained close to systolic blood pressure (ratio of 0.96 +/- 0.06), whereas in group II the IAP ratio showed a decline to 0.34 +/- 0.16 (p = 0.0009 group I versus II). After an initial decrease, the IAP ratio in group III stabilized at 0.75 +/- 0.18 (p = 0.003, group II versus III). Aneurysms with an endoleak remained pulsatile with a pulse pressure of 30 +/- 16 mm Hg, which was less than that of untreated aneurysms (62 +/- 15 mm Hg; p < 0.0001 group I versus III). Arteriography and computed tomography revealed "sealing" of endoleaks after coil embolization, but IAP ratio did not decrease (0.76 +/- 0.14) after coil embolization.

CONCLUSIONS

Incomplete endovascular aneurysm exclusion caused by an endoleak fails to reduce IAP ratio and may subject the aneurysm to a continued risk for rupture. Although coil embolization resulted in angiographic and computed tomographic sealing, it failed to reduce IAP ratio.

Accuracy of duplex ultrasound in evaluating carotid artery anatomy before endarterectomy

PURPOSE

Anatomic features, such as a high carotid bifurcation (< 1.5 cm from the angle of the mandible), excessive distal extent of plaque (> 2.0 cm above the carotid bifurcation), or a small diameter (< or = 0.5 cm) redundant or kinked internal carotid artery can complicate carotid endarterectomy. In the past, arteriography was the only preoperative study capable of imaging these features. This study assessed the ability of duplex ultrasound to evaluate their presence before surgery.

METHODS

A consecutive series of 20 patients who underwent 21 carotid endarterectomies had preoperative duplex ultrasound evaluations of these anatomic features. These evaluations were correlated with operative measurements from an observer blinded to the duplex findings.

RESULTS

The mean difference between duplex and operative measurements for the distance between the carotid bifurcation and the angle of the mandible, the distal extent of plaque, and the internal carotid artery diameter was 0.9 cm, 0.3 cm, and 0.8 mm, respectively. The correlation coefficient between the two methods was 0.86, 0.75, and 0.59, respectively. Duplex ultrasound predicted a high carotid bifurcation, excessive distal extent of plaque, or a redundant or kinked internal carotid artery with 100% sensitivity (p < 0.05, p < 0.01, and p < 0.001, respectively). The sensitivity of duplex ultrasound in predicting a small internal carotid artery diameter was 80%. The specificity of duplex ultrasound for predicting excessive distal extent of plaque, small internal carotid artery diameter, high carotid bifurcation, and a coiled or kinked carotid artery was 92%, 56%, 100%, and 100%, respectively.

CONCLUSION

Duplex ultrasound can predict the presence of anatomic features that may complicate carotid endarterectomy. Preoperative duplex imaging of these features may be helpful in patients who undergo carotid endarterectomy without preoperative arteriography.

Endoleaks after endovascular graft treatment of aortic aneurysms: classification, risk factors, and outcome

PURPOSE

Incomplete endovascular graft exclusion of an abdominal aortic aneurysm results in an endoleak. To better understand the pathogenesis, significance, and fate of endoleaks, we analyzed our experience with endovascular aneurysm repair.

METHODS

Between November 1992 and May 1997, 47 aneurysms were treated. In a phase I study, patients received either an endovascular aortoaortic graft (11) or an aortoiliac, femorofemoral graft (8). In phase II, procedures and grafts were modified to include aortofemoral, femorofemoral grafts (28) that were inserted with juxtarenal proximal stents, sutured endovascular distal anastomoses within the femoral artery, and hypogastric artery coil embolization. Endoleaks were detected by arteriogram, computed tomographic scan, or duplex ultrasound. Classification systems to describe anatomic, chronologic, and physiologic endoleak features were developed, and aortic characteristics were correlated with endoleak incidence.

RESULTS

Endoleaks were discovered in 11 phase I patients (58%) and only six phase II patients (21%; p < 0.05). Aneurysm neck lengths 2 cm or less increased the incidence of endoleaks (p < 0.05). Although not significant, aneurysms with patent side branches or severe neck calcification had a higher rate of endoleaks than those without these features (47% vs 29% and 57% vs 33%, respectively), and patients with iliac artery occlusive disease had a lower rate of endoleaks than those without occlusive disease (18% vs 42%). Endoleak classifications revealed that most endoleaks were immediate, without outflow, and persistent (71% each), proximal (59%), and had aortic inflow (88%). One patient with a persistent endoleak had aneurysm rupture and died.

CONCLUSIONS

Endoleaks complicate a significant number of endovascular abdominal aortic aneurysm repairs and may permit aneurysm growth and rupture. The type of graft used, the technique of graft insertion, and aortic anatomic features all affect the rate of endoleaks. Anatomic, chronologic, and physiologic classifications can facilitate endoleak reporting and improve understanding of their pathogenesis, significance, and fate.

Endovascular approaches for traumatic arterial lesions

Vascular injuries caused by blunt or penetrating trauma can be challenging to diagnose and treat, particularly when they involve central vessels. Endovascular treatment for vascular trauma includes the placement of embolization coils and intravascular stents and the employment of stented grafts. The use of stented grafts appears to be associated with decreased blood loss, a less invasive insertion procedure, reduced requirements for anesthesia, and a limited need for an extensive dissection in a traumatized field. These advantages are especially important in patients with central arteriovenous fistulas or false aneurysms, particularly those who are critically ill from other coexisting injuries or medical comorbidities. In these circumstances, the use of stented grafts already appears justified to treat traumatic central arterial lesions. Endovascular grafts are important tools for the treatment of vascular trauma, and they should be included in the armamentarium of the vascular surgeon.

Varying strategies and devices for endovascular repair of abdominal aortic aneurysms

The endovascular repair of abdominal aortic aneurysms has been investigated in a clinical setting since 1991. Although initially the procedure was performed using surgeon-made devices, it did not take long for the medical industry to realize the potential of this procedure. There are six commercially made devices, which are unique, each with their own strengths and weaknesses. This article describes the principal endovascular graft types that are currently under investigation as well as the strategies for their use. In addition, the inclusion criteria for endovascular repair of abdominal aortic aneurysms are discussed.

Endovascular grafting for aortoiliac occlusive disease

Aortoiliac occlusive disease is a significant cause of lower extremity ischemic symptoms. Over the past two decades, most patients have been treated with a variety of surgical procedures, including aortofemoral and extra-anatomic bypasses. Most recently, percutaneous balloon angioplasty and stents have been successfully used for the treatment of limited iliac lesions. New endovascular grafts that combine vascular grafts with stents in a device with new characteristics may allow the successful treatment of patients with extensive aortoiliac occlusive disease in a less invasive fashion. In our early experience, the endovascular grafts were constructed with Palmaz balloon-expandable stents and standard polytetrafluoroethylene (PTFE) grafts. The 18-month primary and secondary patency rates were 89% and 100%, respectively, with a limb salvage rate of 94%. Endovascular grafts can be successfully used to treat patients with extensive aortoiliac occlusive disease, with excellent early results. Long-term results and further graft improvements will define their role in the treatment of patients with aortoiliac occlusive disease.

Should vascular surgeons perform endovascular procedures and how can they acquire the skills to do so?

Endovascular treatment techniques have already replaced some vascular operations. The likelihood is that new endovascular techniques involving stents and stented grafts will replace additional vascular operations. All of these treatments involve the use of catheter-guidewire, balloon, and imaging modalities, particularly digital fluoroscopy. These modalities have already and will increasingly help to improve and simplify standard vascular operations such as thromboembolectomy, infrainguinal bypasses, and management of aneurysms and arteriovenous fistulas. Accordingly, vascular surgeons must become familiar with and use these endovascular methods and techniques. This can be accomplished in a variety of ways, including working as part of a multidisciplinary vascular treatment group in which various specialists collaborate to provide the best, most cost-effective care to vascular disease patients.

An experimental model for the acute and chronic evaluation of intra-aneurysmal pressure

PURPOSE

To develop an animal model for the acute and chronic monitoring of pressure within abdominal aortic aneurysms (AAAs) to be treated with endovascular grafts.

METHODS

A strain-gauge pressure transducer was placed within an AAA created from a prosthetic vascular graft. Prosthetic aneurysms were implanted into 17 canine infrarenal aortas. The intra-aneurysmal pressure was monitored and correlated with noninvasive forelimb sphygmomanometry for 2 weeks. After this time, an intravascular manometer catheter was passed into the aneurysm. Simultaneous pressure measurements were obtained using the implanted strain-gauge pressure transducer, the manometer catheter, and the forelimb sphygmomanometer. Angiography was performed to assess intraluminal morphology, aneurysm anastomoses, and adjoining aortic vessels. In addition, two control animals underwent intra-aneurysmal pressure monitoring after standard surgical aneurysm repair.

RESULTS

There was excellent correlation (r = 0.97) between the pressure measurements obtained with the implanted strain-gauge pressure transducer and the intravascular manometer. Close correlation was also observed between the implanted strain-gauge transducer and the forelimb sphygmomanometer (r = 0.88) during postprocedural monitoring. Intra-aneurysmal pressure was lowered dramatically by surgical exclusion (aneurysm: 15/5 +/- 7/4 mmHg; systemic: 124/66 +/- 34/17 mmHg; p < 0.001). The prosthetic aneurysms were successfully imaged with angiography.

CONCLUSIONS

This animal model provides an accurate and reproducible means for measuring intra-aneurysmal pressure on an acute and chronic basis. It may be possible to use this model in the assessment of endovascular devices to determine their efficacy in reducing intra-aneurysmal pressure. Evaluation of complications associated with their use, such as patent aneurysm side branches, perigraft channels, and perianastomotic reflux, may also be possible.

Endovascular grafts for noninfected aortoiliac anastomotic aneurysms

PURPOSE

This report describes our experience with endovascular repair of aortic and iliac anastomotic aneurysms.

METHODS

Between June 1994 and March 1996, 12 noninfected aortic or iliac anastomotic aneurysms in 10 patients who had serious comorbid medical conditions that precluded or made difficult standard operative repair were treated using endovascular grafts. No patient in this study had a history of fever, leukocytosis, or computed tomographic evidence of a periprosthetic fluid collection that was suggestive of infection of the original graft. Endovascular grafts composed of polytetrafluoroethylene and balloon-expandable stents were introduced through a femoral arteriotomy and were placed using over-the-wire techniques under C-arm fluoroscopic guidance.

RESULTS

Endovascular grafts were successfully inserted in all patients with aortic or iliac anastomotic aneurysms. There were no procedure-related deaths, and complications included one postprocedure wound hematoma and one perioperative myocardial infarction. Graft patency has been maintained for a mean of 16.1 months, with no computed tomographic evidence of aneurysmal enlargement or perigraft leakage.

CONCLUSIONS

Endovascular grafts appear to be a safe and effective technique for excluding some noninfected aortoiliac anastomotic aneurysms in high-risk patients and may become a treatment option in all patients who have clinically significant lesions.

Chronic intraaneurysmal pressure measurement: an experimental method for evaluating the effectiveness of endovascular aortic aneurysm exclusion

PURPOSE

To evaluate and compare the intraaneurysmal pressure (IAP) after exclusion using two different endovascular grafts.

METHODS

Eight mongrel dogs had a 3 x 3 cm polytetrafluoroethylene (PTFE) aneurysm sewn as an interposition graft of the infrarenal aorta. A pressure transducer implanted into the aneurysm wall permitted continuous electronic IAP monitoring. Four aneurysms were excluded with a transluminally placed endovascular graft made of a PTFE graft and two Palmaz stents (PTFE-EG), three were excluded with a tantalum-Dacron endovascular graft (TD-EG), and one was surgically treated with a standard PTFE graft (PTFE-Surg). The dogs were observed for 18 to 50 days (mean, 37.5 days) and were evaluated after surgery with duplex and spiral computed tomographic scans.

RESULTS

All grafts successfully excluded the aneurysms without perigraft channels or leaks as documented by arteriogram and duplex and computed tomographic scans. The mean IAPs after repair with all PTFE-EGs were significantly lower (p < 0.001) than the mean systemic pressures. In addition, the mean IAP reduction was significantly greater (p < 0.005) in the PTFE-EG group than in the TD-EG group.

CONCLUSIONS

Aneurysm exclusion with PTFE-EG significantly lowered IAP, did so significantly better than the TD-EG, and approached the IAP reduction obtained by standard repair. Such pressure reduction is necessary for effective protection against aneurysm rupture.

Sudden neonatal death in carnitine transporter deficiency

A newborn infant died suddenly and unexpectedly on day 5 of life. Postmortem investigations led to a suspicion of carnitine transporter deficiency, a diagnosis supported by the finding that both parents are heterozygotes for this disorder. The fasting stress caused by poor breast-feeding with no formula supplements and, possibly, the vegetarian diet of the mother were likely the critical factors leading to neonatal death, an outcome previously not described in this disorder.

Anastomotic intimal hyperplasia: a comparison between conventional and endovascular stent graft techniques

Endovascular grafts (EVGs) have been proposed as a treatment for a variety of vascular diseases; however, the impact of EVGs on graft healing has not been fully evaluated. The aim of this study is to compare anastomotic intimal hyperplasia (AIH) and endothelialization in EVGs and conventional bypass grafts (CGs). Seven mongrel dogs received an EVG in one iliac artery and a CG in the other iliac artery using a 5 mm x 4 cm polytetrafluoroethylene graft. The EVG was secured to the native vessel wall, with balloon expandable stents at either ends of the graft. CGs were anastomosed using running sutures. Intravascular ultrasound was performed at the time of sacrifice (8 weeks) to determine percentage of stenosis at the distal anastomosis. Specimens were divided longitudinally for light microscopic analysis (thickness of distal AIH) and scanning electron microscopic studies (percentage of endothelial coverage of the graft). Percentage of stenosis at the distal anastomosis was significantly higher in EVGs compared with CGs (28.2 +/- 18.2% versus 1.8 +/- 2.8%; P < 0.01) due to significantly greater mean intimal thickness in the EVGs (441.1 +/- 101.1 microns versus 82.4 +/- 41.9 microns; P < 0.01). The total percentage of area covered by endothelial cells was also significantly greater in EVGs compared with CGs (80.5 +/- 37.5% versus 30.3 +/- 37.1%; P < 0.05). Intraluminal location enhanced endothelialization of the polytetrafluoroethylene graft; however, it also resulted in greater AIH. Further device refinements including stent design may be required to maximize the potential of these endovascular procedures.

Stent-graft repair of aorto-iliac occlusive disease coexisting with common femoral artery disease

PURPOSE

Significant disease or occlusion of the common femoral artery may preclude percutaneous therapy for aorto-iliac occlusive disease. In addition, aorto-iliac angioplasty may not reverse the ischemic symptoms when common femoral artery disease exists. The authors describe the feasibility of endoluminal stent-grafts to treat multilevel aortoiliofemoral occlusive disease.

MATERIALS AND METHODS

The authors placed 18 stent-grafts for aorto-iliac occlusive disease in 17 patients with limb-threatening ischemia and significant common femoral artery disease. These procedures were performed as a joint effort between vascular surgery and interventional radiology staff in the operating room. The common femoral artery was occluded in 10 or severely diseased in eight, necessitating endoluminal bypass to the superficial femoral or popliteal artery (n = 7) or to the deep femoral artery (n = 7), or necessitating patch angioplasty of the common femoral artery (n = 4). Stent-grafts were fabricated from 6-mm polytetrafluoroethylene and 29-mm Palmaz stents.

RESULTS

All 18 grafts were placed successfully. Follow-up ranged from 3 to 38 months (mean, 21 months). Seven patients died of myocardial infarction; two grafts occluded and one required angioplasty during follow-up, resulting in a primary patency rate of 81% at 2 years.

CONCLUSION

Endoluminal stent-graft placement is a useful method of treatment for advanced atherosclerotic aorto-iliac disease, particularly in the presence of common femoral artery disease. This approach avoids an extra-anatomic bypass or a major transabdominal aortic bypass procedure. Longer follow-up with a larger series is needed to ensure the safety and late graft patency comparable to the traditional aortofemoral and iliofemoral bypass grafts.

Comparison of endovascular and conventional vascular prostheses in an experimental infection model

INTRODUCTION

The causes and management of prosthetic graft infections have been extensively studied for conventional bypass grafts; however, the infectivity and therapy for endovascular graft infections are completely unknown. The aim of this study was to compare the biologic properties of infected aortic grafts when inserted by endoluminal or standard transabdominal techniques.

METHODS

Eighteen dogs underwent placement of polytetrafluoroethylene grafts in their infrarenal aortas either by an endovascular technique (8) or a standard interposition technique (10). Endovascular grafts were constructed from polytetrafluoroethylene (3 cm) and two balloon-expandable stents coaxially mounted onto a balloon catheter delivery system. The grafts were inserted through a left carotid arteriotomy under fluoroscopic control. Initially, seven grafts were infected with decreasing inocula of Staphylococcus aureus, starting at 10(7) organisms per ml for 30 minutes and then rinsed briefly (10 seconds) in normal saline solution, until a 50% infective dose for the standard grafts was determined to be 10(2) organisms per ml. After this initial experiment, a second group of 11 dogs were compared at a concentration of 10(2) S. aureus per ml. Five dogs underwent endovascular repair, and six dogs had standard graft interpositions after an identical period of bacterial exposure. All grafts were removed at 2 weeks under sterile conditions and were submitted for quantitative culture analysis.

RESULTS

Three of the six dogs (50%) with standard grafts appeared to clear their infections, whereas only one of the five dogs (20%) with an endovascular graft was free of organisms at 14 days. This results was further manifested by statistically significant lower postmortem colony counts in the standard grafts (p < 0.01).

CONCLUSIONS

The endoluminal position of the graft and its proximity to the arterial wall do not appear to provide protection against infection. These data suggest that if endovascular grafts become infected, they may be in a disadvantaged position for host defense mechanisms to be effective.

Endovascular aortounifemoral grafts and femorofemoral bypass for bilateral limb-threatening ischemia

PURPOSE

Although axillobifemoral bypass procedures have a lower mortality rate than aortobifemoral bypass procedures, they are limited by decreased patency, moderate hemodynamic improvement, and the need for general anesthesia. This report describes an alternative approach to bilateral aortoiliac occlusive disease using unilateral endovascular aortofemoral bypass procedures in combination with standard femorofemoral reconstructions.

METHODS

Seven patients who had bilateral critical ischemia and tissue necrosis in association with severe comorbid medical illnesses underwent implantation of unilateral aortofemoral endovascular grafts, which were inserted into predilated, recanalized iliac arteries. The proximal end of the endovascular graft was fixed to the distal aorta or common iliac artery with a Palmaz stent. The distal end of the graft was suture-anastomosed to the ipsilateral patent outflow vessel, and a femorofemoral bypass procedure was then performed.

RESULTS

All endovascular grafts were successfully inserted through five occluded and two diffusely stenotic iliac arteries under either local (1), epidural (5), or general anesthesia (1). The mean thigh pulse volume recording amplitudes increased from 9 +/- 3 mm to 30 +/- 7 mm and from 6 +/- 2 mm to 26 +/- 4 mm ipsilateral and contralateral to the aortofemoral graft insertion, respectively. In all cases the symptoms completely resolved. Procedural complications were limited to one local wound hematoma. No graft thromboses occurred during follow-up to 28 months (mean, 17 months).

CONCLUSIONS

Endovascular iliac grafts in combination with standard femorofemoral bypass grafts may be an effective alternative to axillobifemoral bypass in high-risk patients who have diffuse aortoiliac occlusive disease, particularly when bilateral axillary-subclavian disease is present.

Endovascular graft repair of penetrating subclavian artery injuries

PURPOSE

Penetrating subclavian arterial injuries are often difficult to treat. Standard surgical techniques require wide exposure and dissection in traumatized areas, which is often challenging. This report summarizes the early results of endovascularly placed stented grafts for the treatment of penetrating subclavian arterial trauma.

METHODS

Six patients with penetrating injuries of the subclavian artery had stented grafts inserted to repair five pseudoaneurysms and one arteriovenous fistula. The stented grafts consisted of a polytetrafluoroethylene graft sutured over a balloon-expandable Palmaz stent. The devices were inserted from an ipsilateral brachial arteriotomy and deployed using fluoroscopic guidance in the operating room.

RESULTS

Immediate success was obtained in all procedures (100%). All patients continue to have patent grafts with a follow-up ranging from 7 to 30 months (mean 19 months). The only procedure-related complication was the need for a brachial artery patch angioplasty at the site of device insertion in the first patient. There was one other patient who developed a stent fracture at 8 months; a second stent was inserted. Duplex studies up to 24 months later show no recurrence in this patient.

CONCLUSIONS

Endovascular stented grafts offer an effective, less invasive alternative to standard techniques in treating traumatic arterial lesions. Early results are encouraging, but long-term follow-up will be necessary to fully delineate the effectiveness of this technique.

Immunolocalization and temporal distribution of cytokine expression during the development of vein graft intimal hyperplasia in an experimental model

PURPOSE

Vein graft stenosis caused by intimal hyperplasia (IH) accounts for 30% to 50% of late bypass graft failures; however, the biochemical mediators of vein graft IH have been poorly defined. We attempted to evaluate the spatial and temporal distribution of five principal cytokines (interleukin-1 beta [IL-1 beta], platelet-derived growth factor-AA [PDGF-AA], basic fibroblast growth factor [bFGF], interferon gamma [INF gamma], and tumor necrosis factor alpha [TNF-alpha]) during the development of IH in a rat vein graft model.

METHODS

Rat epigastric vein interposition grafts in the femoral artery were harvested at 6 hours, 2 days, 1 week, 2 weeks, and 4 weeks after the grafting procedure and studied with immunohistochemical and standard histologic techniques. The cytokine expression in the endothelium and media/neointima was quantified as the percentage of immunopositive cells per high-power field.

RESULTS

Maximal hyperplasia occurred 2 weeks after the grafting procedure. Peak expression of IL-1 beta and bFGF occurred by 2 days. PDGF-AA expression paralleled the development of IH, peaking at 2 weeks and then declining. TNF-alpha expression increased at 1 week and remained elevated. INF gamma was seen only in control grafts.

CONCLUSIONS

The coordinated early release of IL-1 beta and bFGF and the down-regulation of INF gamma seem to trigger an inflammatory response, thereby initiating IH. The process then is propagated by the release of PDGF-AA and TNF-alpha, with concomitant smooth muscle cell proliferation and production of extracellular matrix. It is likely that this complex milieu of local paracrine signaling is required to generate the hyperplastic response seen in failing vein grafts.

Effect of polytetrafluoroethylene covering of Palmaz stents on the development of intimal hyperplasia in human iliac arteries

PURPOSE

The occurrence of neointimal hyperplasia within a stent may result in restenosis with recurrent symptoms of end-organ ischemia. This study evaluated the potential of a nonporous covering of a stent to function as a barrier to the formation of intrastent neointimal hyperplasia.

MATERIALS AND METHODS

Twelve endovascular stent grafts were used to treat 12 high-risk patients with limb-threatening ischemia secondary to long-segment iliac artery occlusion. A 6-mm, thin-walled polytetrafluoroethylene graft was inserted and anchored to the common iliac artery with use of Palmaz stents. Each stent was covered by graft material over one-half of its length. Control angiograms obtained immediately after graft insertion were compared with follow-up angiograms obtained between 4 and 6 months after the initial procedure. On each angiogram, the region of the stent was magnified by 20x to permit computerized luminal diameter measurements.

RESULTS

The mean luminal diameter within the stent was significantly greater on the covered (7.7 mm +/- 0.33 standard deviation) compared with the uncovered (6.7 mm +/- 0.85 standard deviation) portions (P < .01).

CONCLUSIONS

Partially covered stents are a unique model for assessing the effects of an extrinsic stent covering on arterial healing and myointimal hyperplasia. These data suggest that a relatively nonporous covering of polytetrafluoroethylene may inhibit stent-related restenosis in iliac arteries.

Endovascular repair of aortoiliac occlusive disease

Occlusive disease of the aorta and iliac and femoral arteries may lead to limb-threatening ischemia when multiple levels of disease are present. The combined treatment of severe aortoiliac and infrainguinal disease using standard techniques may be hazardous or contraindicated in patients with multiple, previous reconstructions or severe co-morbid medical illnesses. This report summarizes the technical feasibility and early results of aortoiliac endovascular stented grafts (ESGs) in combination with conventional surgical reconstructions for the treatment of multilevel arterial occlusive disease. Forty-two patients with multilevel aortoiliofemoral limb-threatening occlusive disease had an ESG inserted to treat long-segment, multilevel, occlusive disease. ESGs originated from either the aorta or the common iliac artery and were inserted into one of the femoral arteries. ESG lengths ranged from 16 to 30 cm (mean 21 cm). Conventional surgical bypasses were constructed, when necessary, from polytetrafluoroethylene (PTFE) or saphenous vein and were extended using standard techniques to the popliteal, tibial, or contralateral femoral arteries. Technical success of graft insertion was achieved in 39 of 42 attempted ESG procedures (93%). The 18-month primary and secondary cumulative patency rates for ESGs were 89 +/- 9 (SE) and 100%, respectively. Limb salvage was achieved in 94% of patients at 24 months. Four patients had minor postprocedure complications (10%), and there was one death. Endovascular aortoiliac grafts, often in combination with conventional surgical infrainguinal bypasses, are a technically feasible, potentially safe option for the treatment of limb-threatening aortoiliofemoral occlusive disease and have demonstrated encouraging early patency. Long-term follow-up is necessary before widespread application of this technique is instituted.

Fluoroscopically assisted thromboembolectomy: an improved method for treating acute arterial occlusions

We performed bilateral femoral artery dissections in a single 50 kg mongrel dog. Digital fluoroscopic arteriograms documented the luminal diameter of the left iliac and right superficial femoral arteries. Balloon thrombectomy catheter passage was performed through hemostatic sheaths by 12 surgeons. Embolectomy balloons were filled with radiographic contrast material and the balloon catheter diameter was compared with the underlying vessel diameter. The percentage of overdistention of the embolectomy balloon relative to the arterial wall was 23% +/- 5% in the iliac artery and 40% +/- 13% in the femoral artery. Over a 25-month period, we used fluoroscopically assisted thromboembolectomy to treat 21 patients with acute arterial or graft occlusions. As the balloon was gently withdrawn to extract intravascular thrombus, deformities of the compliant balloon profile caused by underlying arterial lesions were identified fluoroscopically and their locations recorded to facilitate further treatment. After initial clot removal in these 21 patients, 15 residual lesions were documented. Repeat thrombectomy (n = 8), balloon angioplasty (n = 3), and placement of intravascular stents (n = 4) eliminated all 15 lesions. Luminal continuity was successfully restored in all 21 of these patients, 10 of whom required distal open vascular reconstruction to correct existing outflow artery disease. Fluoroscopically assisted thromboembolectomy is a simple and safe method for treating acute arterial or graft occlusions in patients with diffuse arteriosclerosis. It minimizes arterial damage and blood loss during balloon thrombectomy and reduces the need for intravascular contrast agents. It also has the potential to facilitate accurate identification, localization, and treatment of significant underlying arterial lesions.