William V. Sharp

The risk of vascular surgery in a metropolitan community: With observations on surgeon experience and hospital size

From 1978 through 1981 complete perioperative information concerning a total of 10,189 peripheral vascular procedures performed in northeastern Ohio was recorded in the computer registry of The Cleveland Vascular Society. This report is an analysis of mortality and morbidity rates for all 5686 operations involving carotid endarterectomy (N = 2646), lower extremity revascularization (N = 1987), and abdominal aortic aneurysm resection (N = 1053). The operative mortality rate was 1.2% for carotid reconstruction, 2.8% for femoropopliteal or distal bypass, 3.5% for aortofemoral revascularization, and 11.9% for aortic aneurysm resection (elective operations 6.5%; emergency operations 32.9%). Postoperative strokes occurred after endarterectomy in 2.7% of patients having preoperative neurologic symptoms and in 2.0% of those with asymptomatic carotid stenosis. Lower extremity amputation was unavoidable in 1.5% of patients after aortofemoral reconstruction and in 6.0% after femoropopliteal or distal bypass. Statistical testing indicated that the operative mortality rate was not related to the respective size of the 27 hospitals involved in the survey. The relative annual experience of the 29 participating surgeons significantly influenced only the mortality rate of elective aneurysm resection and the amputation rate after femoropopliteal or distal revascularization. This study suggests that the results of major arterial reconstruction in metropolitan areas may be expected to be comparable to those of published series if the responsible surgeons are specifically trained and maintain an active interest in the field of vascular surgery.

Small-diameter vascular prostheses: two designs of PTFE and endothelial cell-seeded and nonseeded Dacron

Despite numerous advances in biomaterials design and utilization, the perfect artificial small-vessel substitute has yet to be developed. Dacron and expanded polytetrafluoroethylene (PTFE) are two materials potentially appropriate for use as small-vessel prostheses. We report the patencies of endothelial cell-seeded and nonseeded 4 mm I.D. Dacron grafts and two designs of nonseeded 4 mm I.D. PTFE (Gore-Tex and Impra) in the carotid position in dogs. All graft lengths exceeded the calculated maximum critical length for the material being tested. Dacron grafts, both endothelial cell-seeded and nonseeded, achieved higher patencies than both designs of PTFE. Endothelial cell-seeded Dacron grafts achieved the highest patencies. Endothelium was present to a significant extent only on endothelial cell-seeded Dacron grafts. There was little pannus ingrowth or midgraft pseudointima on nonseeded Dacron or on patent PTFE grafts although thrombus-free surface areas of patent PTFE grafts were high. These comparative data support the utility of endothelial cell seeding in achieving high patencies of small-diameter vascular grafts.

Material and structural characterization of human saphenous vein

Saphenous vein patch rupture after carotid endarterectomy is an infrequent but devastating complication. This study was undertaken to evaluate the material and structural properties of fresh human saphenous veins to understand the causes of this complication. Segments of saphenous veins were obtained from 22 patients from vein harvested during coronary artery bypass surgery. Ninety-three specimens, oriented in both circumferential (n = 45) and longitudinal (n = 48) directions, were prepared from the available vein segments for testing. Specimens were mounted on specially designed grips and then subjected to uniaxial tension testing. For each specimen the following material and structural parameters were determined: vessel diameter, tensile stiffness, failure and ultimate forces, and tensile modulus, failure stress, and strain. The physical properties of specimens evaluated in longitudinal orientations and thus limit the inherent strength of the vein. The physical properties of circumferentially tested vein specimens were negatively correlated to age, female gender, diabetes, and hypertension. The data obtained in this investigation suggest that age, hypertension, as well as diabetes and gender may adversely influence the circumferential tensile strength of human saphenous veins used as patch grafts.

A metropolitan experience with infrainguinal revascularization: Operative risk and late results in northeastern Ohio

Despite being of fundamental importance, the late results of major arterial reconstruction rarely have been documented throughout a large metropolitan area. In this study of 932 patients entered into the computer registry of the Cleveland Vascular Society, 19 surgeons representing 13 community hospitals and referral centers in Cleveland and Akron report the intermediate-term outcome during a mean interval of 35 months after infrainguinal lower extremity revascularization performed in northeastern Ohio from 1978 through 1982. Operative risk (5%), the early amputation rate (7%), and actuarial 5-year survival (48% to 55%) for patients with rest pain or tissue necrosis were significantly worse (p less than 0.05) than comparable figures (0.6%, 0%, and 77%, respectively) for others who underwent procedures for disabling claudication. Although both materials had similar success above the knee, the cumulative 3-year patency rate of autogenous vein bypass to the distal popliteal (69% to 88%; p less than 0.05) and tibioperoneal arteries (43%; 0.05 less than p less than 0.1) was superior to the results of polytetrafluoroethylene grafts (32% to 50% and 19%, respectively). Moreover, polytetrafluoroethylene grafts required reoperations at three times the rate of vein grafts to maintain limb salvage.

Effects of antiplatelet agents in combination with endothelial cell seeding on small-diameter Dacron vascular graft performance in the canine carotid artery model

The purpose of this study was to assess the success of endothelial cell-seeded and non-seeded small-diameter vascular grafts in dogs medicated with antiplatelet agents. Eighty dogs underwent bilateral carotid artery replacements with 6 cm lengths of 4 mm I.D. double-velour Dacron grafts. In each dog one graft was seeded with enzymatically derived autologous endothelial cells; the contralateral graft was nonseeded. The following anti-platelet medications were administered beginning 4 days preoperatively: aspirin (5 grains every day); dipyridamole (50 mg twice a day); aspirin plus dipyridamole (5 grains each day plus 50 mg twice a day); aspirin (1.25 grains every other day); ibuprofen (10 mg/kg/day); U-53,059, a cyclooxygenase inhibitor (3 mg/kg/day); and U-63557A, a thromboxane synthase inhibitor (10 mg/kg/day). Grafts were harvested 5 weeks postoperatively. Graft success was evaluated by patency, thrombus-free surface area, area endothelialized, and graft production of prostacyclin. None of the medications prevented neoendothelialization of seeded grafts. Mean patencies of endothelial cell-seeded grafts from medicated dogs were significantly greater than mean patencies of endothelial cell-seeded grafts from nonmedicated dogs. The cyclooxygenase inhibitors best maintained patency in nonseeded grafts. Thrombus-free surface areas of endothelial cell-seeded grafts from medicated dogs were significantly greater than from nonseeded control grafts from the medicated dogs. All medications impaired prostacyclin synthesis. We conclude that the combination of endothelial cell seeding plus antiplatelet medication is most efficacious in small-vessel grafting success and that high levels of prostacyclin production by vascular grafts are not necessary to maintain patency in dogs medicated with antiplatelet agents.

Modern autotransfusion: Experience with a washed red cell processing technique

The technique of intraoperative autotransfusion utilizing the Haemonetics Cell Saver is described. This device separates and washes red blood cells removed from the surgical field. Advantages of this unit over others are (1) no systemic anticoagulation is required, (2) circulatory fibrin debris is removed, (3) plasma hemoglobin is removed, and (4) any circulating anticoagulant is removed. Experience with 136 consecutive cases. 101 elective and 35 emergency, is reported. The only complication was coagulopathy, which occurred in 5.1 percent of the cases. It is easily treated with blood component therapy and occurs in those patients in whom greater then 3,500 cm3 of blood is autotransfused. The Cell Saver has proven an important adjunct in surgical patients in whom greater than 1,000 cm3 of blood will be lost, as well as in emergency patients. It provides an efficient, economical and safe method to autotransfuse blood.

Pharmacologic modulation of intimal hyperplasia in canine vein interposition grafts

PURPOSE The purpose of this study was to evaluate the efficacy of three drugs (cilazapril, cyclosporine, and aspirin) in modulating the progression of intimal hyperplasia during short postoperative times in short-segment, autogenous vein bypass grafts in a canine model. The relative effects of the drugs on the progression of intimal hyperplasia were compared with the Gilman parameter, a measure used extensively as a wound healing descriptor. To our knowledge this is the first use of the Gilman parameter in assessing vascular disease. METHODS Seventy-two conditioned mongrel dogs were randomly and equally divided according to a three-factor analysis of variance. The factors included (1) drug treatments (cilazapril [10 mg/kg/day], cyclosporine [4 mg/kg/day], aspirin [325 mg/day], and control [nonmedicated]), (2) implantation sites (femoral and carotid arteries), and (3) postoperative times of graft harvest (1, 3, and 6 weeks). Each dog had 2 cm segments of autogenous jugular vein interpositioned bilaterally into each of the paired carotid and femoral arteries. Quantitative data on luminal narrowing over time from intimal hyperplasia were compared from calculated Gilman parameters after image analysis of retrieved, histologically processed graft sections. RESULTS The observed variability in the data was attributed to drug treatments and time. At 1 week after operation the mean Gilman parameters did not differ significantly among the treatment groups in either midgraft or distal graft segments. At 3 weeks the mean Gilman parameters of midgraft and distal graft sections of cyclosporine-treated dogs differed significantly (p < 0.05) from those of the control group and the cilazapril and aspirin-treated groups, which did not differ from each other. At 6 weeks after operation, mean Gilman parameters from aspirin- and cyclosporine-treated dogs differed statistically from control and cilazapril-medicated dogs and from each other (p < 0.001). CONCLUSIONS These data support the efficacy of aspirin and cyclosporine in reducing intimal hyperplasia in short-segment arterialized vein grafts during short postoperative periods. Additional studies are required to ascertain whether the beneficial effects of aspirin and cyclosporine persist long-term.

Derivation of Human Microvascular Endothelial Cells for Prosthetic Vascular Graft Seeding

This report summarizes our techniques and experiences deriving microvascular endothelial cells from fat for vascular graft seeding in 17 patients. Microvascular endothelial cells were derived from abdominal wall fat by collagenase incubation. The mean number of cells obtained using the described procedure was 6.83 x 10(5) cells/gram of fat processed. Histologic evaluation of the harvested cells revealed significant numbers of contaminating cell types in addition to Factor VIII-positive microvascular endothelial cells. These cells were seeded onto 6 mm ID PTFE vascular grafts in patients undergoing peripheral vascular arterial revascularization. The mean number of seeded cells was 8.04 x 10(6) cells/graft. Approximately 90 minutes were required to harvest and isolate the microvascular cells from the fat samples. We feel there are significant technical advantages to deriving endothelial cells from microvessels of human fat for vascular graft seeding.

Prostaglandin biochemistry of seeded endothelial cells on Dacron prostheses

The beneficial effect of seeding endothelial cells on synthetic vascular conduits has been well established. The biochemical production and interaction of the prostaglandins, prostacyclin (PGI2) and thromboxane (TxA2), were studied on Dacron vascular grafts that were seeded with autogenous venous endothelial cells. Seventy-three seeded and nonseeded grafts were implanted into the carotid arteries of dogs. Animals were medicated with either cyclooxygenase inhibitors (aspirin and dipyridamole, or ibuprofen, or U-53,059), or dipyridamole alone, or a thromboxane synthase inhibitor, U-63557A. All animals were killed at 5 weeks and analyzed for patency, thrombus-free surface (TFS), and PGI2 and TxA2 production from mid-graft punch biopsies. PGI2 and TxA2 identifications were made by radioimmunoassay determination of 6-keto PGF1 alpha and TxB2, respectively. Results of the study demonstrated in nonmedicated animals a slightly increased patency rate in seeded vs. nonseeded grafts (50% vs. 40%) and a more significant difference in TFS (49% vs. 24%). The addition of cyclooxygenase inhibitors or TxA2 synthase inhibitors significantly improved both patency (90% vs. 47%) and TFS (87% vs. 9%) in seeded vs. nonseeded grafts. PGI2 production was decreased in seeded grafts with the use of cyclooxygenase inhibitors in all cases. It is concluded that seeded endothelial cells on Dacron velour grafts can synthesize PGI2; these PGI2 levels are far less than PGI2 levels produced by endothelial cells from the adjacent carotid artery; and TxA2 synthase inhibitors best improve thromboresistance of seeded grafts without significant reduction in PGI2 production.

Microvascular Endothelial Cell Seeding of Small-Diameter Dacron|2TM|0 Vascular Grafts

One obstacle to the clinical implementation of endothelial cell seeding of vascular prostheses is the difficulty in derivation of large numbers of autologous endothelial cells from blood vessels of patients requiring vascular grafting. Capillary endothelial cells obtained from fat have been suggested as an abundant alternative to large-vessel endothelium for graft seeding. The object of this study was to evaluate the performance of 4-mm internal diameter (ID) Dacron™ Microvel grafts seeded with omentally derived microvascular endothelial cells. Six-cm lengths of the test grafts were implanted bilaterally into canine carotid arteries. One of each pair of grafts was seeded with endothelial cells (x = 8.4 × 106) derived from collagenase digestion of autologous omental fat samples. The contralateral graft of each pair was nonseeded. At 5 weeks postoperatively, the grafts were harvested and evaluated. The mean patencies of both the seeded and nonseeded grafts were 89 percent. The mean thrombus-free surface are...