Massimo D'Addato

Total excision and extra-anatomic bypass for aortic graft infection☆

Reports of high mortality and amputation rates following total excision and extra-anatomic bypass for aortic graft infection have prompted the use of alternate approaches including local antibiotics, partial resection, in situ revascularization, and graft excision without revascularization. Experience with aortic graft infection was reviewed to establish current morbidity and mortality rates and evaluate our bias in favor of total excision and extra-anatomic bypass. Aortic graft infection was identified in 32 patients, 8 with aortoenteric fistulas. The mean interval between graft placement and infection was 34 months. History of groin exposure (75%) or multiple prior vascular surgery (50%) was common. Clinical signs included fever and/or leukocytosis (23 patients), false aneurysm (9 patients), graft thrombosis (6 patients), groin infection (11 patients), and gastrointestinal hemorrhage (6 patients). Microbiologic data, available in 26 patients, demonstrated gram-positive organisms in 15 patients and gram-negative in 9. Multiple organisms were seen in 11 patients. Patients were treated by partial removal with (8 patients) or without (4 patients) revascularization or total removal with (18 patients) or without (2 patients) revascularization. Revascularization was by an extra-anatomic route, either simultaneous or staged. Overall morbidity/mortality was less in the revascularized groups (p = 0.01), while late complications were seen only after partial removal (p less than 0.01). The best results were found after total excision with revascularization. No patient in this group experienced late infection or amputation during a mean follow-up of 34 months (range: 1 to 168 months). Complications after total excision and extra-anatomic bypass for aortic graft infection are lower than generally appreciated. This approach should remain the standard to which other approaches are compared.

Postoperative course of inflammatory abdominal aortic aneurysms

Of 779 patients undergoing repair of abdominal aortic aneurysms over a 7-year period (1984–1990), 40 (5.1%) had gross features of inflammatory abdominal aortic aneurysms (IAAAs). Twenty IAAAs were assessed by CT scan preoperatively and postoperatively to evaluate the outcome of the inflammatory layer of the aneurysm in 19 cases. Complete postoperative regression was observed in nine cases (47.3%), partial regression in four (21%), and stable lesions in six (31.7%). No roentgenographic progression was found. The comparison between the roentgenologic outcome and preoperative clinical features (age, sex, erythrocyte sedimentation rate, and abdominal lumbar pain), pathologic findings, and follow-up time revealed a significant correlation (p<0.05) between the postoperative outcome and the histologic findings in the wall (cell density and cell/fibrosis ratio). Complete regression of inflammation was observed when high cell density (16±0.7 cells/2116 µm2) and a cell/fibrosis ratio >1 were found. On the contrary, little or no regression of inflammation occurred when a low cell density (3.4±0.3 cells/2116 µm2) and a cell/fibrosis ratio < 1 were found. Although it is generally thought that inflammation in IAAAs regresses after surgical repair, in our study, 31.7% of the postoperative CT scans showed no change. Histologically, the variability of morphologic aspects seemed to correlate with the relative proportions of cellular infiltrate and interstitial fibrosis in the aneurysmal wall. These proportions determine the postoperative course of the inflammation layer and, most likely, the response of the latter to steroid therapy as well.

Prophylaxis of graft infection with rifampicinbonded Gelseal graft: 2-year follow-up of a prospective clinical trial

Between March 1991 and June 1992, 600 patients were treated with mono-, bifemoral or iliofemoral arterial graft revascularization for occlusions and/or aneurysms. The patients were divided into two groups: group A (n = 296) received a Gelseal Vascutek graft immersed for 15 min before implant in a solution containing 1 mg/ml rifampicin; group B (n = 304) received an untreated Gelseal Vascutek graft. Both groups received perioperative antibiotic treatment with cephalosporins. Clinical follow-up was performed at 1, 6, 12 and 24 months after surgery to exclude signs of graft infection. Statistical analysis (X(2)) of pre-, intra- and postoperative risk factors showed both groups to be well matched. Among 600 patients treated, the 2-year follow-up showed 12 cases of graft infection (2.0%): five in group A (1.7%) and seven in group B (2.3%) (P = n.s.). All cases of graft infection originated in the groin and Staphylococcus aureus was isolated in 50% of cases. Statistical analysis (Mann-Whitney U test) showed a significant prevalence of lymphatic complications and immediate redo surgery in patients with graft infection. Of the 12 cases with infection, one was lost to follow-up, three were treated with total graft removal, six with partial graft removal and two with conservative therapy: there were no deaths. In spite of the relatively limited series and follow-up, no statistically significant difference emerged from the clinical use of vascular grafts pretreated with antibiotics.

Failure of thrombolytic therapy to improve long-term vascular patency

PURPOSE Few data are available on long-term follow-up of arterial segments subjected to thrombolysis. We reviewed all cases of vascular occlusion treated with urokinase to identify early success and determine the influence of postlysis intervention and the nature of the thrombosed segment (i.e., artery vs graft) on long-term patency. METHODS Data on 134 cases (58 arteries, 76 grafts) treated with high-dose urokinase infusion in the lower limbs over a 7-year period were analyzed. Limbs were divided into five groups on the basis of therapy after lytic infusion to determine long-term efficacy: group I, success with no additional therapy; group II, percutaneous angioplasty alone; group III, limited surgical procedure (operative angioplasty, jump graft); group IV, extensive procedure (new bypass); and group V, revascularization after lytic failure. Long-term results were assessed by life-table analysis and groups compared by log-rank test (Mantel-Haenszel). RESULTS Initial patency was established in 87 (64.9%) of 134 cases with 5 deaths (3.7%), 11 amputations (8.2%), and 16 complications (11.9%). Follow-up was available in 68.6% of cases for a mean of 10.9 months. No difference was seen between grafts and native arteries. Patency was analyzed at 6, 12, 18, and 24 months. The 24-month patency rate after lysis alone (group I-25.9%) was inferior (p < 0.05) to results after lysis and any subsequent intervention (groups II, III, and IV). The type of intervention did not influence subsequent patency. Twenty-four-month patency of procedures performed after failed thrombolysis (group V, 41.4%) was not different from those after successful lysis (groups I to IV). Twenty-four-month patency in groups II and III (minor interventions, 62.9%) was not significantly different from that of groups IV and V (major interventions, 53.2%) (p > 0.25). CONCLUSIONS Operative intervention is required to produce long-term arterial patency, even after successful thrombolysis. No statistically significant benefit of thrombolysis on vascular patency was seen in our series.

Endovascular Repair as First-Choice Treatment for Anastomotic and True Iliac Aneurysms

Purpose: To report our experience with the endovascular repair of iliac aneurysms secondary to aortoiliac bypass grafting. Methods: Thirteen patients (12 men; age range 62–86 years) with histories of aortoiliac reconstructions were treated with endovascular stent-grafts for 11 false and 2 true iliac aneurysms that averaged 5.2 cm in diameter (range 3.0–7.0). Via a percutaneous access and 9-F or 12-F sheaths, Passager or Wallgraft stent-grafts were delivered to exclude the aneurysms. Results: Twelve (92%) of 13 interventions were completed satisfactorily; 1 procedure for a true iliac aneurysm was converted to traditional bypass grafting. Two patients underwent additional surgical procedures. The average hospital stay for the patients with endovascular repairs only was 3 days (range 2–5). After a mean follow-up of 28 months (range 17–40), no complication or endoleak has been detected in any patient, and all endografts are patent. Conclusions: Endovascular repair is an effective treatment for secondary aneurysms arising after aortoiliac surgery. It is less invasive and involves a shorter hospital stay. Endovascular repair should be the first choice treatment for iliac aneurysms.

The cellular component in the parietal infiltrate of inflammatory abdominal aortic aneurysms (IAAA)

Eight cases of inflammatory abdominal aortic aneurysm (IAAA) (group I) and a control group of ten cases of atherosclerotic abdominal aortic aneurysm (AAA) with little or no parietal inflammatory infiltrate (group II) were studied; using light microscopy, transmission electron microscopy (TEM), and immunohistochemistry. These were used to define cell composition in the inflammatory process, the degree of cell activation and alteration of connective tissue. Large numbers of B lymphocytes were present in IAAA with preservation of the T4/T8 ratio. In addition, HLA-DR and the IL2-R antigen (specific for activated cells) were widely expressed in the cell population. The interstitial matrix contained deposits of IgG, IgM and C3c together with an increase in type III collagen and a reduction in elastin which appeared fragmented and swollen. This study, therefore, characterised the cellular component of the parietal inflammatory infiltrate in IAAA. The degree of activation shown by these cell elements and the activation of complement suggest that the relevant antigen may have been localised in the aneurysm wall at the time of observation.

Content and turnover of extracellular matrix protein in human “Non-specific” and inflammatory abdominal aortic aneurysms

Inflammatory aneurysms (IAs) have peculiar macroscopic and histological aspects which make them very different from nonspecific aneurysms (NSAs). These morphological differences seem to be determined by significant modifications of the extracellular matrix. Extracellular matrix protein component concentrations were determined biochemically in infrarenal aortic biopsies from 10 NSAs, five IAs and five non-aneurysmal aortic controls. The concentration of each wall component was expressed in % w/w (relative concentration) and in mg/wall longitudinal cm (absolute concentration) with reference to total protein recovered after hydrolysis and amino acid analysis. The biochemical results were correlated with the histological and ultrastructural features of the specimens. A significant increase in total collagen was observed in the two groups of aneurysms, with respect to the controls (NSA = 285%, IA = 382%). In contrast the 80-90% decrease in the relative concentration of elastin observed in both types of aneurysm was less marked (NSA = 55%, IA = 39%). This fall was not significant when expressed in mg/cm, although elastin derived peptide (EDP) levels in the plasma of these patients was significantly higher than in age-matched controls. The concentration of the soluble collagen fraction appeared significantly higher (Mann-Whitney, p < 0.05) in the IAs with respect to the NSAs, whilst no differences were observed between the two groups regarding the concentration of insoluble elastin and of wall and plasma EDPs. As well as providing evidence of increased elastin turnover, this study emphasises the conspicuous modifications of collagen deposition in the wall of abdominal aortic aneurysms which appeared more marked in the inflammatory group.(ABSTRACT TRUNCATED AT 250 WORDS)

Elastic Modulus in Young Diabetic Patients (Ultrasound Measurements of Pulse Wave Velocity)

Aim of this study is to confirm the validity of non-invasive evaluation with Doppler C.W. in the study of arterial diseases and in the identification of pre- clinical arterial lesions. We studied twenty-eight children suffered from mellite diabetes and depend ent on insulin and a control group composed of twenty-eight healthy persons. All subjects were studied using the methodology of the transit time for the determination of the elastic modulus of the lower limb arterial wall and results were analysed according to a statistical method. Although the groups were small, an increase in pulse wave velocity was noted in diabetic children and a significative correlation was found between the elastic modulus and duration of diabetes.

An Ultrastructural and Immunocytochemical Analysis of Human Endothelial Cell Adhesion on Coated Vascular Grafts

Human adult endothelial cells were enzymatically harvested from adipose tissue. Cell viability was established by Trypan blue exclusion and transmission and scanning electron microscopy. Endothelial cells were identified by immunocytochemical investigation at light microscopy, transmission electron microscopy, and scanning electron microscopy. Isolated cells were positive for actin and vimentin, negative for desmin. Factor VIII RA was mainly expressed at cell surface and occasionally disclosed in the cytoplasm. Reactivity for UEA I and J15 was weak or undetectable. Human endothelial cells were seeded and left to adhere for one hour onto different nonvascular substrates (glass, poly-l-lysine, formvar-carbon, fibronectin, Teflon). Scanning electron microscopy defined surface features, suggesting tenacious cell adhesion on the substrate. Different vascular substrates were tested (preclotted Dacron, albumin Dacron, Hemashield Dacron, Gelseal Dacron, ePTFE, fibronectin-ePTFE). Commercially available coated grafts showed qualitative and quantitative differences in cell adhesion. In particular, Gelseal Dacron provided the best quantitative results, even though a wide variability was observed. In contrast, fibronectin-coated ePTFE gave more reliable results and high spreading efficiency. In the short term, coated grafts do not seem to offer greater advantages than fibronectin-coated ePTFE. However, specific incubation times for each coated graft should be selected and the long-term approach (graft culture) should also be attempted.

Electron Microscopic and Immunocyto- chemical Profiles of Human Subcutaneous Fat Tissue Microvascular Endothelial Cells

The ultrastructural and immunocytochemical characteristics of microvascular cells from human subcutaneous fat tissue were studied after the addition of collagenase and Percoll density gradient, respectively. Monoclonal and polyclonal antibodies directed against antigens specific for endothelial cells (factor VIII,Ulex europeaus, CD31, and CD34), pericytes (muscle-specific actin and desmin), adipocytes (S-100 protein), and monocytes-macrophages (MAC 387 and 150.95 protein) were demonstrated by alkaline phosphatase monoclonal antialkaline phosphatase and protein A-gold techniques. In addition, to determine whether the harvesting method interfered with microvascular cell function, DOT immunoassays of factor VIII and CD34 were conducted on solutions recovered at collagenase incubation as well as after nylon filtration and Percoll administration, respectively. After the collagenase step, the vast majority of microvascular cells had the typical ultrastructural and immunophenotypical features of endothelial cells. In sharp contrast, following the Percoll step, only 1% to 18% of microvascular cells stained with factor VIII,Ulex europeaus, and CD31, whereas 90% of them expressed the CD34 antigen. Surprisingly, DOT immunoassay revealed the presence of factor VIII in the washing buffer recovered after the Percoll step only. Consequently the decreased expression of common endothelial cell markers (factor VIII,Ulex europaeus, and CD31) observed at the end of the cell isolation procedure was related to the adverse effects of Percoll on endothelial cell function. The CD34 surface molecule, being highly resistant, is particularly well suited for unequivocal characterization of microvascular cells as true endothelium.