Glutaraldehyde-tanned Human Umbilical Vein Research Articles

Femoropopliteal prosthetic bypass with glutaraldehyde stabilized human umbilical vein (HUV)

Femoropopliteal bypass still is the standard surgical therapy for disabling claudication and critical ischemia. When autologous vein is not suitable synthetic or biological prostheses may be considered. Second generation glutaraldehyde tanned human umbilical vein (HUV) graft was chosen for above and below knee femoropopliteal bypass when autologous vein was not available. A single center experience regarding long-term graft function, secondary reinterventions, and potential biodegeneration of the HUV is presented. Between January 1994 and January 2005, 211 consecutive femoropopliteal bypass operations with HUV (65 above knee and 146 below knee) were performed in 197 patients for disabling claudication (57), chronic critical ischemia (130), popliteal artery aneurysm (9), acute ischemia (14), or aneurysmal degeneration of a synthetic graft (1) in the absence of suitable ipsilateral great saphenous vein. Grafts were followed with duplex scan supplemented by additional angiography in case of recurrent ischemia with prospective documentation of follow-up data in a computerized vascular database. Surveillance of the HUV included routine evaluation of potential biodegeneration with duplex scan. Retrospective analysis of graft patency, limb salvage, and signs of aneurysmal degeneration was performed. Mean (median) follow-up was 44 (35) months (range 1 to 143 months). Thirty-day mortality was 2.4%. Early postoperative bypass thrombosis after a median of 4 days postoperatively (0 to 30 days) prompted revision with thrombectomy in 16% of cases. Besides late bypass thrombosis in 14.7%, additional operative or endovascular reinterventions during follow-up to maintain or restore graft patency was necessary in 8.5% of bypasses. Primary, primary assisted, secondary patency rate, and limb salvage rate after 5 years were 54%, 63%, 76%, and 92%, respectively, for all bypasses with no significant difference between above and below knee anastomosis. Duplex scan identified segmental aneurysmal degeneration in six grafts, which led to operative reintervention in three cases. The rate of detected aneurysm for grafts patent for more than three years was 7% with a rate of reintervention for aneurysm of 3.5%. Although a considerable rate of early thrombotic occlusions occurred, excellent secondary graft patency and limb salvage combined with a tolerable rate of late aneurysmal degeneration detected by means of duplex scan surveillance justify the use of the HUV in femoropopliteal bypass surgery when ipsilateral autogenous vein is not suitable.

Biodegradation of glutaraldehyde-tanned human umbilical vein grafts.

A retrospective analysis of the long-term behavior of 111 glutaraldehyde-tanned human umbilical vein (HUV) grafts implanted between September 1977 and December 1993 was conducted. A total of 81 patients, with a mean age of 68.7 years, received the grafts and were followed up for between 1 and 131 months. The 5-year primary cumulative patency rate for above-knee femoropopliteal bypass was 83.1%, whereas that of other bypasses was 60.9%. An aneurysm of the graft was defined as a physically apparent localized dilatation, with diffuse ectasia being excluded. There were 11 aneurysms found in 9 grafts, 2 of which arose at the factory-made suture lines. The accumulated incidence of aneurysms had reached 21.9% by the 6th year. One aneurysm compressed the graft and resulted in limb-threatening ischemia and another resulted in frank rupture. Moreover, reinforcement of the mesh could not prevent aneurysm development, the repair of which is mandatory due to the risk of rupture and acute thrombosis. The HUV grafts showed an acceptable patency rate in the above-knee location, but the incidence of aneurysm formation after 5 years was abnormally high. Thus, both the risks and benefits of HUV grafts must be taken into account when considering their clinical application.

A clinicopathologic study of aneurysm formation of glutaraldehyde-tanned human umbilical vein grafts

To clarify the process of graft degeneration and aneurysm formation we reviewed the angiographic and pathologic findings of three cases where aneurysms developed in glutaraldehyde-tanned human umbilical vein grafts. Seven aneurysms were detected in these three grafts 4 years after implantation. Six aneurysms originated from the bodies of the grafts and one originated from the factory-created anastomosis required for fabrication. Wrinkling and segmentation of the dilated graft documented by arteriography corresponded to mural dissection of the graft wall. Large protrusions near the aneurysms were revealed to be the transmurally dissected graft walls. At the site of dissection, blood escaped through the surrounding mesh of the graft to form a preaneurysmal change. Two aneurysms developed without breakdown of the outer mesh. The aneurysm of factory-created sutures was caused by tearing of the graft wall. Degeneration of human umbilical vein grafts, which appears to ensue inevitably with the passage of time after implantation, leads to the tear of the graft wall and transmural dissection to form aneurysm. In our department, candidates for human umbilical vein graft implantation have recently been restricted to the patients whose life expectancy is limited to only a few years because of the risk of aneurysm formation.

Long-Term Evaluation of Human Umbilical Vein as Small-Caliber Arterial Substitute

Since 1977, 61 arterial reconstruc tions using glutaraldehyde-tanned human umbilical vein (HUV) grafts were carried out in 56 patients (51 males, 5 females) with unsuitable au togenous saphenous vein. Their mean age was 69 ± 14 years. Limb salvage was the primary indication for sur gery. HUV grafts were used to perform 44 femoropopliteal, 4 composite aor topopliteal (with a direct end-to-end anastomosis between an aortofe moral Dacron graft and a femoropo pliteal HUV graft), 5 femorotibial, and 6 axillofemoral bypasses, and 1 femorofemoral and 1 iliopopliteal by pass. Ten-year cumulative patency rates were 31 % for all HUV recon structions, 36% for femoropopliteal bypasses, and 32% for femoropopli teal bypasses carried out for limb sal vage only. Four of the 5 femorotibial reconstructions failed during the first month following surgery. Two of the 6 axillofemoral and 3 of the 4 com posite aortopopliteal bypasses throm bosed within one and three years after surgery respectively. In conclu sion, the study evidenced long-term durability of HUV grafts, supporting their use for femorodistal reconstruc tions in patients with limb-threaten ing ischemia and inadequate autoge nous saphenous vein.

Prediction of aneurysm formation in vascular grafts of biologic origin

Other than review of clinical experience, no assay exists that can reliably predict the long-term potential for aneurysm formation in an arterial prosthesis of biologic origin. Since mural degeneration probably results from proteolytic digestion, an in vitro assay was devised that used graft perfusion with 1% collagenase to induce rapid changes in mechanical properties. The effect of enzyme on graft diameter, compliance, permeability, and burst pressure was measured in ficin-digested, adipoyl chloride and glutaraldehyde-tanned bovine carotid artery and glutaraldehyde-tanned human umbilical vein. Both grafts have recently been reported to have a significant incidence of aneurysm within several years of implantation. Compliance and diameter were also measured noninvasively in patients with bovine carotid artery and human umbilical vein for more than 40 weeks after implantation. In vitro, the response to enzyme could be categorized into three groups. In group III, a diameter increase of more than 14% was associated with a significantly decreased compliance, and this paralleled the results found in aneurysmal grafts in vivo. In both grafts there was a strong correlation between postenzyme compliance change and initial compliance, loss of compliance being significantly greater in grafts with group III responses (p less than 0.01). This response may be a good predictor of a graft's overall susceptibility to aneurysmal degeneration, and initial compliance measurement may effectively identify inadequate fixation. Thus measurement of compliance may prove useful in quality control of a fixation process used in mass production. In conclusion, measurement of mechanical properties of biologic vascular grafts before and after collagenase exposure forms the basis for an effective in vitro assay of aneurysm susceptibility.

Prediction of aneurysm formation in vascular grafts of biologic origin

Other than review of clinical experience, no assay exists that can reliably predict the longterm potential for aneurysm formation in an arterial prosthesis of biologic origin. Since mural degeneration probably results from proteolytic digestion, an in vitro assay was devised that used graft perfusion with 1% collagenase to induce rapid changes in mechanical properties. The effect of enzyme on graft diameter, compliance, permeability, and burst pressure was measured in ficin-digested, adipoyl chloride and glutaraldehydetanned bovine carotid artery and glutaraldehyde-tanned human umbilical vein. Both grafts have recently been reported to have a significant incidence of aneurysm within several years of implantation. Compliance and diameter were also measured noninvasively in patients with bovine carotid artery and human umbilical vein for more than 40 weeks after implantation. In vitro, the response to enzyme could be categorized into three groups. In group III, a diameter increase of more than 14% was associated with a significantly decreased compliance, and this paralleled the results found in aneurysmal grafts in vivo. In both grafts there was a strong correlation between postenzyme compliance change and initial compliance, loss of compliance being significantly greater in grafts with group III responses (p < 0.01). This response may be a good predictor of a graft's overall susceptibility to aneurysmal degeneration, and initial compliance measurement may effectively identify inadequate fixation. Thus measurement of compliance may prove useful in quality control of a fixation process used in mass production. In conclusion, measurement of mechanical properties of biologic vascular grafts before and after collagenase exposure forms the basis for an effective in vitro assay of aneurysm susceptibility.

Healing and Long-Term Viability of Grafts in the Venae Cavae Reconstruction

The need for superior vena cava (SVC) or inferior vena cava (IVC) recon struction is not uncommon: lung cancer, mediastinal tumors, or retroperitoneal neoplasms are the most frequent indications for caval replacement. Since auto genous veins, which represent the most satisfactory venous substitute, have not been applicable to caval replacement, because of the lack of suitable length and caliber, many types of materials have been tested in the venous system. The present study was planned to compare the potential of expanded polytetrafluoroethylene (e-PTFE) and glutaraldehyde-tanned human umbilical vein (HUV) grafts as caval substitutes. Patch (4 x 5 cm) reconstruction of the SVC was carried out in 10 dogs, tubu lar (3 x 10 mm) reconstruction of the SVC in 5 dogs, and patch (1 x 2 cm) recon struction of the IVC in 8 dogs. In the patch reconstruction groups, HUV grafts were used in half of the cases and 30 μm pore sizes e-PTFE grafts in the other half, while in the tubular SVC replacement group, only e-PTFE grafts were employed. The grafts were removed fifteen to thirty days after IVC patch re construction, thirty to two hundred seventy days after SVC patch reconstruc tion, and thirty-three to forty-one months after SVC tubular replacement. In every instance, specimens were obtained for light microscopy (LM) and scan ning electron microscopy (SEM). HUV patches implanted in the SVC showed hemorrhagic foci at their central portion and marked constriction at the anastomotic regions. On the contrary, the inner surface of e-PTFE patch grafts was covered with a uniform and glis tening neointima. By LM, e-PTFE patches showed a smooth and regular lumi nal surface, while the inner surface of HUV patches was irregular, with hemorrhagic areas in the underlying layers. By SEM, e-PTFE patches revealed a more rapid and orderly endothelialization of their inner surface than HUV patches did. Tubular SVC reconstruction showed the good long-term viability of the e-PTFE neointima (as long as forty-one months after grafting). Only spotty areas revealed neointima alterations, such as fibrinoid degeneration, fo cal necrosis, or minor thrombotic foci. In the IVC patch reconstruction model, HUV grafts showed an exuberant fibrin deposition on their inner surface and delayed endothelialization patterns, as compared with e-PTFE grafts. Since rapid healing with rapid endothelialization is accepted as the most important factor providing the graft luminal surface with the best antithrombotic proper ties, the present study demonstrated that e-PTFE is a more suitable material than HUV for SVC and IVC reconstruction.

Comparison of platelet adherence and aggregation in modified human umbilical vein and autogenous vein grafts

The use of glutaraldehyde-tanned human umbilical vein as a vascular conduit has recently become popular. In previous studies in our laboratory, neointimal fibrous hyperplasia was responsible for poor long-term patency of this material in a canine model. The present study was undertaken to compare the platelet-adhering characteristics of autogenous vein and modified human umbilical vein. After platelets were labelled with chromium-51, 10 mongrel dogs underwent bilateral end-to-side femoral artery bypass grafts. Human umbilical vein and autogenous jugular vein were placed in opposing groins of each dog. Two hours after graft implantation, the animals were killed and the grafts retrieved along with 1 cm of the host artery at each anastomosis. These specimens and an aliquot of blood were placed in a scintillation counter and radioactivity levels were determined. The human umbilical vein had significantly more platelet adherence than the autogenous veins as determined by counts per gram per 10 minutes. The handling characteristics of human umbilical vein were also suboptimal. Separation of the graft layers was occasionally observed, sometimes resulting in intramural hematomas and graft dissection. The previously reported poor performance of human umbilical vein in the canine model is most likely a result of its platelet-adhering surface and poor handling characteristics.