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PubMed1987

Effect of compliance mismatch on vascular graft patency.

The hypothesis that a mismatch in compliance between a vascular graft and its host artery is detrimental to graft patency was tested by implanting paired arterial autografts, prepared with differential glutaraldehyde fixation of carotid arteries in the femoral arteries of dogs. These grafts differed only in circumferential compliance: they were 100% (compliant) vs. 40% (stiff) as compliant as the host artery. Their flow surfaces were equivalent, as determined by physicochemical measurements and scanning electron microscopy; both lacked viable cells, as determined by in vitro cell culture. In 14 dogs, eight stiff and two compliant grafts became occluded within 3 months, the latter doing so within 24 hours after their contralateral counterparts. Cumulative patencies were 85% and 37% for compliant and stiff grafts, respectively (p less than 0.05) and 100% and 43%, excluding the two dogs with bilateral graft failures (p less than 0.01). We conclude that even with near optimal flow surfaces, compliance mismatch is deleterious to graft patency.

Animals↗
PubMed2003

Improving the patency of vascular bypass grafts: the role of suture materials and surgical techniques on reducing anastomotic compliance mismatch.

BACKGROUND: compliance mismatch is an important factor in the development of myointimal hyperplasia in both coronary and vascular anastomoses. This mismatch may be reduced by the use of newer suture materials and techniques. This review discusses the current techniques and materials used to date in generating anastomoses in both coronary and vascular applications and to correlate these with the degree of inherent compliance achieved. METHODS: PubMed, ISIS, CAS and PAS database searches were performed. Other articles were cross-referenced. RESULTS AND CONCLUSION: continuous suture is still the most used technique in both cardiac and vascular surgery for the generation of anastomoses due to the reduced time and improved haemostasis. However, continuous suture results in a greater compliance mismatch than the interrupted technique. Vein cuffs and patches improve compliance and transmission of pulsatile blood flow and offer improvement of graft patency. Alternative to sutures are biological glue, clips and laser generated solders all of which have shown promising results, but further work is required before they become applicable for routine use.

Anastomosis, Surgical↗
PubMed1992

A new bioactive molecule for improving vascular graft patency: exploratory trials in dogs.

Myxalin is a new bioactive molecule that we have isolated from the culture medium of Myxococcus xanthus, a non-pathogenic Gram negative bacterium. This glycopeptide possesses an antithrombotic effect in vivo and has been shown to promote human endothelial cell growth in vitro. With the object of exploring its ability to improve vascular graft healing and patency, myxalin was immobilized on 6 mm diameter knitted polyester prostheses using gelatin as a carrier, and the prosthesis was then implanted as an infrarenal abdominal arterial substitute in dogs for a period of 2 weeks. Two additional series of implantations were conducted for control purposes: one with gelatin-coated prostheses without myxalin, the other following normal preclotting of the polyester grafts. In order to select adequate sterilization conditions which can preserve the biological activity of myxalin, the prostheses were sterilized according to 3 different sterilization processes (gamma radiation and ethylene oxide either at 63 degrees C or 37 degrees C). At the sacrifice, all grafts were patent. The myxalin treated prostheses exhibited improved blood compatibility in terms of fewer thrombotic deposits and significant inhibition of platelet and fibrinogen uptake on their luminal surfaces. In addition, the development of a thin collagenous internal capsule with endothelial cells secreting high levels of prostacyclin was observed at both anastomoses of the myxalin-treated grafts sterilized by gamma radiation.

6-Ketoprostaglandin F1 alpha↗
PubMed1995

Parameters of prognostic relevance to the patency of vascular access in hemodialysis patients.

The objectives of this study were to evaluate whether age, sex, underlying renal disease, or the performing surgeon is of prognostic relevance to the patency of the vascular access. In a routine clinical setting, 139 first and 144 further fistula operations were done in 139 patients during 5 yr and were analyzed in retrospect. Within a group of 108 patients with first Cimino-Brescia fistulae, Cox multivariate regression analysis revealed the surgeon to be the only determinant with a continuous, significant effect on fistula patency throughout the observation period (P(out) < 0.1). The patency rates of the seven surgeons at 1, 2, and 3 yr differed from 34 to 69, 13 to 62, and 13 to 62%, respectively. Hazard ratios among the surgeons varied from 0.65 to 2.21. Additionally, age (P < 0.004) and diabetes mellitus (P < 0.02) were disclosed to be significant risk factors for impaired patency, but later in the course of disease (time dependent). Sex had no influence. After the failure of the first fistula, revisions of or new Cimino-Brescia fistulae (N = 56) were superior to polytetrafluoroethylene grafts (N = 61). The mean patency of the former amounted to 320 +/- 377 versus 156 +/- 281 days in polytetrafluoroethylene grafts (P < 0.05). It was concluded that increasing age and diabetes mellitus are time-dependent risk factors for the shortened patency of arteriovenous fistulae. The operating surgeon, however, seems to be the major determinant for the continuous patency of Cimino-Brescia fistulae.

Adolescent↗
PubMed1987

Bilateral ankle skin temperature as a predictor of early vascular graft patency.

The efficacy of postoperative bilateral ankle skin temperature as a predictor of early graft patency was prospectively evaluated in 138 consecutive cases of femoropopliteal bypass surgery. The difference between ipsilateral and contralateral ankle temperature (hourly registrations) was significantly greater in the patients with patent graft on postoperative day 1 than in those with an occluded graft. In measurements 8 h postoperatively, highest sensitivity (84 per cent) and specificity (93 per cent) of the test were obtained when the difference was +0.4 degrees C. The overall accuracy of prediction with this simple method was 89 per cent.

Adult↗
PubMed1995

Maintenance of permanent hemodialysis vascular access patency.

The morbidity and mortality of maintenance hemodialysis patients are in large part determined by the ability of the nephrologist, dialysis staff, and vascular surgeon to establish and maintain adequate vascular access. Primary arteriovenous fistulae are the preferred form of vascular access because they are the more likely to provide long-term complication-free access. In 1994, however, the majority of patients entering hemodialysis programs have vascular anatomy unsuitable for primary arteriovenous fistula creation. Synthetic fistulae are currently the more common form of vascular access. Unfortunately, this form of vascular access is more prone to thrombosis and infection. Thrombosis is the most common cause of vascular access loss. Venous stenoses account for the majority of thromboses but can be prospectively identified by performing routine measurements of venous dialysis pressure or urea recirculation. Prospective identification of venous stenoses followed by either angioplasty or surgical revision will improve fistula patency and enhance the quality of life of the hemodialysis population.

Arteriovenous Shunt, Surgical↗
PubMed1994

Blocking of endothelial-leukocyte interaction (rolling) does not improve reflow in the rat gastric mucosa after hemorrhagic shock and retransfusion.

The polymorphonuclear neutrophilic granulocyte (PMN) has been implicated as one possible cause of the no-reflow phenomenon seen upon reperfusion after ischemia, by, for instance, the release of toxic substances and/or microvascular flow obstruction. In the present study we studied the effects of ascorbate (an antioxidant) and fucoidin (an inhibitor of leukocyte rolling in microvessels) on the rat gastric mucosal and submucosal PMN content and vascular patency (the latter assessed as the surface density of perfused vessels) in connection with hemorrhagic shock (15 min) and retransfusion (5 or 10 min). The effect of fucoidin on the leukocyte rolling in small venules was studied separately with vital microscopy in the rat mesentery. As found in earlier studies, shock and retransfusion led to a decrease in the surface density of perfused vessels, whereas the number of PMNs in the mucosa or the submucosa was not affected by shock and retransfusion. Ascorbate improved vascular patency without affecting the PMN content. In the mesentery, fucoidin caused a 76% reduction in the number of rolling PMNs and it reduced significantly the number of PMNs in the mucosa, but not in the submucosa, after 10 min of retransfusion. Fucoidin had no effect on the vascular patency at that or any other time point. On the basis of these experiments it is concluded that PMN accumulation cannot be singled out as the cause of no-reflow in the rat gastric mucosa after shock and retransfusion of the degree and duration analyzed in this investigation.

Animals↗
PubMed1998

Color Doppler imaging assessment of blood flow in vascularized pedicle grafts for avascular necrosis of the femoral head: angiographic correlation.

The aim of this study was to examine whether color Doppler imaging can be used to assess vascular patency after use of pedicle pelvic bone grafts in the operative treatment of avascular necrosis of the femoral head. We performed color Doppler imaging and selective angiography in 10 consecutive patients (12 hip joints) treated for avascular necrosis of the femoral head. In comparison to angiographic results, nine patent and two occluded grafts were demonstrated correctly by color Doppler imaging. In one case, a graft confirmed as patent by angiography was not demonstrable by color Doppler imaging. Accuracy, sensitivity, and specificity of color Doppler imaging were high when compared to angiography as a standard. Color Doppler imaging is suited to evaluate vascular patency after use of vascularized pedicle bone grafts in the treatment of avascular necrosis of the femoral head.

Angiography↗
PubMedDate not supplied

The validity of canine platelet aggregometry in predicting vascular graft patency.

Several laboratories have found canine platelet aggregometry predictive of thrombotic potential in vascular grafts. Adenosine diphosphate (ADP) is a frequently used agonist, often at unspecified or differing concentrations. This study was designed to evaluate the predictive value of ADP-induced platelet aggregometry and the validity of the methodology. Platelet aggregometry in response to 2 x 10(-5) M ADP was assayed in 70 dogs. Twenty-six percent were aggregators, 51% were non-aggregators, and 20% were indeterminant. All dogs were then treated with aspirin and dipyridamole. Vascular prostheses were implanted bilaterally (aorto-iliac) and anti-platelet therapy continued for two weeks. Dose-response to ADP was studied at three concentrations in 20 dogs. At 2 x 10(-5) 1/20 aggregated, at 4 x 10(-5) 3/19 aggregated and at 2 x 10(-4) 15/20 aggregated. Time between samples and study was evaluated in 11 dogs, with 2/11 changing from non-aggregator to aggregator at two or three hours. Daily reproducibility was studied in 70 dogs, 14 of which changed aggregation status between days. Patency was 58/68 (85%) for non-aggregators, 23/34 (68%) for aggregators (p = 0.038). Platelet aggregometry has significant predictive value for graft patency but methodology must be specified and standardized.

Adenosine Diphosphate↗
PubMed1992

The influence of diabetes on free flap transfer: II. The effect of ischemia on flap survival.

Insulin-dependent diabetes mellitus causes microangiopathic changes in many tissues, including skin and muscle. It is not known if such changes are detrimental to free flap transfer, particularly after extended ischemia. To address this issue, we used an experimental design by using a syngeneic rat strain (Lewis) for free groin flap and muscle flap transplantations from streptozotocin-induced diabetic rats (2 month's duration of symptoms) to normal rats. Flaps from age-matched normal donors were transplanted to normal recipients for control comparisons. Groin flaps were stored ischemically for 12 or 18 hours at room temperature, or for 48 hours in the cold (4 degrees C) before transplantation. Flap survival and vascular patency were assessed at 7 days. Cutaneous maximus muscle flaps were transplanted to the groins of recipients after 6 hours of room temperature ischemia. Vascular patency, muscle viability, flap weight change (edema), and dehydrogenase activity were assessed after 2 days of reperfusion. Seventy percent, 67%, and 73% of diabetic groin flaps survived after 12, 18, or 48 (cold) hours of ischemia, respectively, in comparison with 90%, 73%, and 87% of normal flaps undergoing the same respective ischemia periods. The differences were not significant, even when the data were pooled (p greater than 0.1). Muscle flaps also showed no significant differences for the parameters studied. These results support the use of microvascular reconstructive surgery in diabetic patients, suggesting that moderate ischemic challenges do not compromise free flap transfer or extremity replantation.

Animals↗
PubMed1998

Warfarin sodium (Coumadin) anticoagulant therapy for vascular access patency.

The increase of geriatric and diabetic patients with poor vasculature brings about a corresponding increase in the use of synthetic vascular access grafts. Synthetic vascular accesses are plagued with numerous problems in maintaining patency. As a result, many practitioners use warfarin sodium. Coumadin, because of its predictability and bioavailability to interrupt the coagulation cascade to prevent thrombus formation. This article includes actions, interactions, monitoring, and adverse effects of this drug.

Anticoagulants↗
PubMedDate not supplied

Multislice CT angiography through an implantable catheter and port system: early experience in detection of vascular complications during hepatic arterial infusion chemotherapy.

OBJECTIVE: The purpose of this study was to evaluate the use of multislice CT in the evaluation of vascular patency in patients during hepatic arterial infusion chemotherapy of liver tumors. MATERIALS AND METHODS: Thirty-three patients were prospectively examined by CT angiography through the indwelling catheter and port system. Visibility of hepatic arteries and vascular patency were graded 0 to 3 and were compared with digital subtraction angiography (DSA). RESULTS: Average visualization scores of CT angiography and DSA were 1.7 and 2.5, respectively, in common hepatic artery (CHA) and proper hepatic artery (PHA), 2.5 and 2.3 in right hepatic artery (RHA), 2.6 and 2.6 in left hepatic artery (LHA), 2.3 and 2.2 in segmental RHA, and 2.1 and 2.0 in segmental LHA. Stenoses were found in proximal hepatic arteries in 9 on CT angiography and 13 on DSA. Stenoses were found in branches of the hepatic artery in 21 on CT angiography and 16 on DSA. CONCLUSION: The authors' results indicate that multislice CT angiography of the hepatic arteries is equivalent to DSA and may demonstrate vascular complications of hepatic arterial infusion chemotherapy.

Adult↗
PubMed2002

Improving the clinical patency of prosthetic vascular and coronary bypass grafts: the role of seeding and tissue engineering.

In patients requiring coronary or peripheral vascular bypass procedures, autogenous vein is currently the conduit of choice. If this is unavailable, then a prosthetic material is used. Prosthetic graft is liable to fail due to occlusion of the graft. To prevent graft occlusion, seeding of the graft lumen with endothelial cells is undertaken. Recent advances have also looked at developing a completely artificial biological graft engineered from the patient's cells with properties similar to autogenous vessels. This review encompasses the developments in the two principal technologies used in developing hybrid coronary and peripheral vascular bypass grafts, that is, seeding and tissue engineering.

Blood Vessel Prosthesis↗
PubMed1995

Comparison of antithrombotic effects of GPIIb-IIIa receptor antagonist and TXA2 receptor antagonist in the guinea-pig thrombosis model: possible role of TXA2 in reocclusion after thrombolysis.

The effects of Ro 44-9883, a new specific antagonist of platelet glycoprotein IIb-IIIa receptor, on thrombus formation and reocclusion after thrombolysis induced by tissue-type plasminogen activator (t-PA) were compared with those of vapiprost, a thromboxane (TX) A2 receptor antagonist, using a photochemically-induced thrombosis model in the guinea-pig femoral artery. Pretreatment with Ro 44-9883 (5, 10 and 20 micrograms/kg/min, i.v.) prolonged the time required to occlude the artery in a dose-dependent manner. Ro 44-9883 at 10 and 20 micrograms/kg/min significantly inhibited ex vivo platelet aggregation in whole blood induced by collagen, ADP or U46619. Vapiprost 0.3 mg/kg inhibited thrombus formation and platelet aggregation induced by collagen or U46619, to the same extent as Ro 44-9883 at the higher doses. In the thrombolysis study, Ro 44-9883 at the higher doses given as comedication with t-PA reduced the time to achieve reperfusion and increased the vascular patency after successful reperfusion. Vapiprost also significantly reduced the time to reperfusion and prevented reocclusion. However, the vascular patency after thrombolysis by t-PA with vapiprost was significantly increased compared with Ro 44-9883. Ro 44-9883 inhibited platelet aggregation, but did not prevent TXA2 formation in platelets. Thus, vascular contraction mediated by platelet-derived TXA2 may be responsible for lower efficacy of Ro 44-9883 against reocclusion compared with vapiprost. These results indicate that not only platelet aggregation but also vasoconstriction may contribute to reocclusion after t-PA-induced thrombolysis in the guinea-pig.

Acetates↗
PubMedDate not supplied

Magnetic resonance angiography of intravascular endoprostheses: investigation of three devices.

PURPOSE: To assess the value of magnetic resonance angiography (MRA) in the evaluation of vascular patency after intravascular endoprosthesis placement. METHODS: Three different metallic stents (Wallstent, Strecker, Palmaz) were studied in vitro, and in vivo in six patients with spin-echo (SE) and gradient-echo (GRE) MR imaging. Time-of-flight, two-dimensional (2D) gadolinium-enhanced MRA was performed with GRE and flow-compensation technique, and reconstructed with a maximum-intensity projection (MIP) algorithm. MRA was compared to digital angiograms. RESULTS: In vitro studies demonstrated that the signal intensity (SI) within the stent differed according to the device employed, the lowest SI being observed within the Palmaz stent (p = .001). There was no difference in SI or apparent diameter of the stent according to the sequence (SE vs GRE) or length of echo time (TE). In patients, the endoprostheses recorded as a well-defined area of signal void or drop-out (p = 0.004), whereas vessels above and below the stent displayed high signal intensities. CONCLUSION: MRA does not seem as yet to be well suited for evaluating vascular patency after endoprosthesis placement, even if the Strecker and Wallstent endoprostheses provide fewer artifacts than the Palmaz stent.

Arterial Occlusive Diseases↗
PubMed1996

Rat whole-limb viability after cold immersion using University of Wisconsin and Euro-Collins solutions.

The purpose of this study was to compare University of Wisconsin (UW) solution with Euro-Collins (EC) solution in their cold preservation effects on rat limbs. Thirty-six Lewis rat limbs were preserved in EC solution (n=18) or UW solution (n=18) at 4 degrees C for 72 hr, and grafted orthotopically to a syngeneic rat using microsurgical techniques. The surgeon was blinded to the solution used. We evaluated the vascular patency rate and death rate of both groups at day 7 after surgery and performed histological evaluations of bone, muscle, growth plate, and articular cartilage for each specimen of successful grafts in both groups. The vascular patency rates of the EC and UW groups were 27.7% (5/18) and 11% (2/18), respectively, and showed no significant difference. The death rates of the EC and UW groups were 50% (9/18) and 60% (10/18), which were not significantly different. There were no clear differences in histological viability between both groups, in all tissues exclusive of bone marrow and muscle tissue. Our results showed that in comparing EC and UW solutions, one was not significantly superior to the other as a cold immersion storage medium after a 72 hr ischemia-induced reperfusion injury.

Adenosine↗
PubMed1992

Protective effects of coenzyme Q10 on ischemia-induced reperfusion injury in ischemic limb models.

We examined simple cold preservation of rat limbs in Euro-Collins' solution to elucidate the protective effect of coenzyme Q10 (CoQ10) on the ischemia-induced reperfusion injury in an ischemic extremity replant model. A total of 126 Lewis rat limb replants were performed. Limbs were amputated from donor rats and preserved at 4 degrees C in Euro-Collins' solution and were orthotopically grafted to isogeneic rats by microsurgical technique. In the experimental groups (n = 42), coenzyme Q10 (10 mg/kg) was injected intraperitoneally into the recipients about 1 hour before reperfusion. In the control groups (n = 84), the same dose of solvent was given by the same route. We evaluated vascular patency of anastomoses by direct observation or microangiogram and performed histologic examinations 7 days after replantation. In the control groups, the ischemic limit was 96 hours. Ischemic limbs treated with coenzyme Q10 showed a statistically significant (p < 0.05) improvement in vascular patency after 72 and 96 hours of ischemia. Histologically, bone viability with osteoblastic activity was maintained in coenzyme Q10-treated animals of the 72-hour ischemic group. We conclude that the protective effect of coenzyme Q10 on reperfusion injury is suggested in this replant model.

Animals↗