Correlation of long-term results of extra-anatomic bypass and flow waveform analysis

Patency Rates of Femorofemoral Bypasses Associated with Endovascular Aneurysm Repair Surpass Those Performed for Occlusive Disease

Purpose:

To evaluate the patency rates of femorofemoral grafts performed in conjunction with aortomonoiliac or aortomonofemoral (AMI/F) endografts.

Methods:

Over the past 8 years, 110 patients (98 men; mean age 77 ± 7 years, range 57–90) underwent aortoiliac aneurysm repair with an AMI/F endograft. Follow-up data in these patients were prospectively collected for a mean 2.3 years (range 1–68 months).

Results:

There were 2 early (<7 days) AMI/F endograft thromboses with secondary femorofemoral graft occlusion. In both patients, patency of all grafts was restored by thrombectomy plus stenting of the endograft. Three late (4, 5, and 10 months) AMI/F endograft thromboses led to femorofemoral graft failure; 2 were successfully treated, but the third patient refused further intervention. No femorofemoral bypass failed in the absence of AMI/F endograft thrombosis. There were no femorofemoral graft infections. Four-year life-table primary and secondary patency rates were 95% and 99%, respectively.

Conclusions:

Femorofemoral bypasses with AMI/F endografts for aneurysmal disease are durable procedures and have better patency than femorofemoral grafts used to treat occlusive disease. Femorofemoral bypass patency rates alone are not a disadvantage of aortomonoiliac endografts.

Endovascular AAA Repair With the Aortomonoiliac EndoFit Stent-Graft: Two Years' Experience

PURPOSE

To evaluate the feasibility and efficacy of a specific aortomonoiliac endograft and the durability of the femorofemoral bypass for treatment of abdominal aortic aneurysm (AAA).

METHODS

From 2002 to 2004, 39 high-risk (ASA III/IV) patients (36 men; median age 74 years, range 63-84) with AAA (n = 33) or AAA and common iliac artery aneurysm (n = 6) were treated with an EndoFit aortomonoiliac endograft and femorofemoral crossover bypass. The contralateral iliac axis was obstructed with an endoluminal occluder. Patients were followed with contrast-enhanced computed tomography at 1, 6, 12, and 24 months.

RESULTS

EndoFit AMI stent-grafts were implanted successfully in all patients. Perioperative mortality was zero. Endoleak occurred in 3 (7.7%) cases. A proximal type I endoleak was identified at 1 month and was treated with a proximal cuff. Two type II endoleaks are under surveillance because the aneurysm sac shows no enlargement. Thrombosis of the femorofemoral graft occurred in 1 case during the immediate postoperative period due to insufficient inflow from a residual stenosis of the endograft (primary patency 97.5%). The deficit was treated successfully (secondary patency 100%). Two (5.1%) tunnel hematomas were treated conventionally. Median follow-up was 14 months (range 6-30). All patients are alive. None of the aneurysms has ruptured or been converted to an open procedure. Graft migration, serious infection, paraplegia, distal embolization, or any other serious complication has not been observed.

CONCLUSIONS

In high surgical risk patients with complex iliac anatomy, aortomonoiliac endograft with femorofemoral crossover bypass is feasible and efficacious. Moreover, the midterm patency of the extra-anatomic bypass appears quite satisfactory.

Intraluminal gene transfer of endothelial cell-nitric oxide synthase suppresses intimal hyperplasia of vein grafts in cholesterol-fed rabbit: a limited biological effect as a result of the loss of medial smooth muscle cells

BACKGROUND

The intimal hyperplasia of vein grafts is a major cause of late graft failure and is more pronounced under hyperlipidemia. We previously reported that endothelial cell (ec)-type nitric oxide synthase (NOS) gene transfer inhibited graft intimal hyperplasia under poor runoff conditions. However, little information is available on either ecNOS gene transfer or intimal thickening under hypercholesterolemia.

METHODS

Using the hemagglutinating virus of Japan liposomes, bovine ecNOS complentary DNA (5000 hemagglutinating activity units/mL) was transfected intraluminally to the right jugular vein, and these veins were then implanted as reversed vein grafts in an end-to-side fashion to the ipsilateral carotid artery.

RESULTS

The cyclic guanosine 3',5'-monophosphate content of the ecNOS vein significantly increased in the grafts at 4 days after gene transfer, but the levels were only 25% greater than those found in the untreated veins. An immunohistochemical analysis at the same time suggested a large loss of medial smooth muscle cells that might have led to a reduction in the exogenous gene expression. The neointima of the ecNOS grafts was significantly reduced 4 weeks after implantation (P <.05), but the effect of ecNOS was limited to about a 30% inhibition. This reduction was associated with a reduced population of proliferating cells and decreased macrophage accumulation in the graft wall.

CONCLUSIONS

These results demonstrated that the ecNOS gene transfer suppressed intimal hyperplasia of the vein grafts under hyperlipidemic conditions. However, this effect may be limited because of the smooth muscle cell loss related to the use of an intraluminal delivery methods. These data lead to speculation that the outcome of ecNOS gene transfer could be improved using different methods of gene delivery.

Gene therapy in vascular surgery comes of age

In the last decade, gene therapy for cardiovascular diseases has been becoming a reality. However, although numerous successful experimental studies have suggested possible strategies of gene therapy for cardiovascular disorders, the clinical outcome remains limited. Because cardiovascular diseases are the result of complex causes, there is no exact answer to the following question: Which is the best gene to treat vascular diseases? In addition, current limitations include less clinically relevant vectors regarding both gene-transfer efficiency and safety, and at present, most efforts are focused on identifying more effective therapeutic genes, as well as developing more effective vectors. Furthermore, greater pathophysiologic understanding of these diseases, including vein-graft remodeling and ischemic limbs, is required. Regarding the relevant vector, we recently developed a novel mononegavirus-based gene-transfer vector, namely recombinant Sendai virus, which has shown dramatically superior gene-transfer efficiency to other vectors, including adenovirus, in several organs (eg, the vessel wall and skeletal muscles). These efforts now offer new possibilities to get more fruits in the field of gene therapy for vascular surgery.

Immunohistochemical phenotypic alterations of rabbit autologous vein grafts implanted under arterial circulation with or without poor distal runoff-implications of vein graft remodeling

Although intimal hyperplasia is a major cause limiting the long-term patency of the vein grafts, its precise mechanisms, including the effect of poor runoff, has not yet been well characterized. We thus designed the present study to try to determine the effect of poor runoff arterial flow to the phenotypic alterations of the graft wall by immnohistochemistry using anti-intermediate filaments (alpha-SM actin, desmin, and vimentin) and anti-myosin heavy chain (SM1, SM2, and SMemb) specific antibodies. Vein grafts implanted under the poor runoff hind limb of rabbits showed enhanced intimal hyperplasia, however, no apparent difference in the cytoskeleton expression, including intermediate filaments and MHC, between two groups until 4 weeks. Interestingly, six of eight vein grafts at 2 weeks after implantation in both groups showed the accumulations of perivascular fibroblast-like phenotype (negative for SM1, alpha-SM actin, and desmin) in some parts of the outer neointima, whereas the inner neointima at 2 weeks and the whole neointima at 4 weeks were mainly occupied by a smooth muscle phenotype (positive for these three). Although the cellular origin of these cells is still unknown, these results suggest that the migration of non-muscle mesenchymal cells is involved in the neointima and thus may provide a clue for better understanding vein graft remodeling.

Femorofemoral bypass, even in pregnancy--a case report

A 29-year-old pregnant woman sustained blunt, left lower abdominal trauma, with hip and pelvic fractures, and progressive dissection of an intimal flap in the left iliac artery, which manifested two days later as profound ischemia of the left leg. The patient underwent distal thromboembolectomy, fasciotomies and revascularization of the leg by femorofemoral polytetrafluoroethylene bypass. The patient recovered completely and gave normal birth three months later to a healthy child. Four years after the operation she gave uneventful birth to another child. Various considerations pertinent to this complex traumatic-vascular-gestational state are discussed.

Late graft failure of autologous vein grafts for arterial occlusive disease: clinical and experimental studies

Late graft failure following arterial reconstructive surgery, especially after infrainguinal reconstruction, remains a major concern for vascular surgeons. To more effectively predict the outcome of reconstructed arteries, we herein propose an intraoperative flow waveform analysis which correlates well with the long-term patency rate of grafts. According to this flow waveform analysis, late graft failure was occasionally seen in grafts with type II waveforms when poor distal runoff vessels had been shown by the preoperative arteriogram. Next, to investigate which events occurring in autologous vein grafts under abnormal hemodynamics may contribute to late graft failure, a distal poor-runoff model was made in the canine femoral artery. In this review, we present the results of our investigation on autologous vein grafts using this poor-runoff model. We also relate our recent findings on the function of regenerated endothelium in autologous vein grafts.