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Biomedical subjects

W V Sharp

Publications and source records attributed to W V Sharp.

At least 37 records · Page 2Linked to original sources
PubMed1985

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.

Animals↗
PubMed1985

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.

Animals↗
PubMed1984

Blunt trauma to the axillary artery.

Blunt trauma to the axillary artery is an unusual injury. Patients with these injuries may not present with "classic" signs of arterial insufficiency; therefore a high index of suspicion is necessary to avoid delay in treatment. This article presents three patients with unusual injuries to the axillary artery and discusses their management.

Adult↗
PubMed1984

Endothelial cell--seeded four-millimeter Dacron vascular grafts: effects of blood flow manipulation through the grafts.

The objective of this study was to compare the surface thrombogenicities of endothelial cell-seeded small-diameter vascular grafts with those of nonseeded contralateral grafts under conditions of acute controlled low blood flows through the grafts in a canine carotid artery model. Autologous venous endothelial cells seeded in the preclots onto 6 cm sections of 4 mm (internal diameter) double-velour Dacron grafts covered 15% and 80% of graft luminal surfaces at 3 and 5 weeks postsurgically, respectively. Contralateral nonseeded control graft lumina had pannus ingrowth of endothelium across the anastomoses only. There were significant differences in initial carotid graft blood flow rates between seeded and control grafts at both 3 and 5 weeks postsurgically. When blood flow was reduced to 30% of the initial flow levels for 4 hours through these grafts, endothelial cell-seeded grafts maintained patencies and mean blood flow returned to 63.3% and 93% of initial flow levels at 3 and 5 weeks postsurgically, respectively. Few thrombi accumulated. In contrast, thrombi accumulated on nonseeded graft lumina during restricted blood flow. Some nonseeded grafts occluded during low flows, and the ratios of final flow to initial flow were only 28% at 3 weeks and 20% at 5 weeks in these nonseeded grafts. These data demonstrate the efficacy of seeding autologous endothelial cells on small-diameter grafts in this canine model. If technically successful, endothelial cell seeding may provide a protocol for enhancement of the long-term implantation success of small-diameter vascular grafts used for human vascular repair and replacements.

Animals↗
PubMed1984

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.

Aorta, Abdominal↗
PubMed1984

Persistent sciatic artery: two case reports with emphasis on embryologic development.

Prior to development of the femoral arterial system, the sciatic artery serves as the principal blood supply to the lower extremity in the embryo. There have been only 32 reported cases in the world literature of a persistent sciatic artery in the adult. Two additional cases are presented in this report with a review of the embryologic development of the arterial system in the lower extremity. Diagnosis and treatment of associated problems involving the sciatic artery are discussed.

Aged↗
PubMed1983

Controlled flow studies in 4 mm endothelialized dacron grafts.

Endothelial cell seeding of 4 mm ID double velour dacron vascular grafts promoted luminal endothelial cell surfacing and improved small-diameter graft performance as evidenced by the following: Flow rates through endothelial cell seeded grafts were higher than through nonseeded control grafts. With increasing postsurgical time the flow rates through seeded grafts increased as a consequence of greater luminal endothelial cell coverage. During low flow conditions endothelial cell seeded grafts retained thrombus-free surface characteristics whereas thrombus accumulated during low flow in nonseeded grafts. Some nonseeded grafts occluded during low flow. The ability of seeded grafts to retain thrombus-free surfaces during low flow increased with increasing postoperative time as a consequence of greater luminal endothelial cell coverage. Endothelial cell seeding is an efficacious approach to maintaining graft patency during conditions of reduced blood flow.

Animals↗
PubMed1982

Endothelial cell seeding of small-diameter vascular grafts.

Small-diameter double velour dacron vascular grafts were seeded with autologous canine endothelial cells, implanted in the canine carotid arteries and the in vivo progress of graft luminal endothelial surfacing followed. Sixty-five percent of the experimental grafts were successfully seeded. Comparison of patency, endothelial cell coverage, thrombus-free surface, and inner capsule thickness between seeded and control grafts revealed enhancement of graft performance by cell seeding. Peroxidase-antiperoxidase staining was utilized to positively identify graft luminal endothelium.

Animals↗
PubMed1982

Suture resistance to infection.

The emergence of both absorbable and nonabsorbable synthetic materials has been primary among the many new developments in suture materials. This is a study of 16 types of natural and synthetic suture materials and their resistance to both gram-positive and gram-negative infections. Four hundred and twenty suture inplants were made in the Edlich mouse model. The 16 different sutures were compared to appropriate controls and graded by the degree of infectibility. Synthetic sutures were superior in all areas. The monofilament sutures performed better than the multifilament sutures. Lubricating coatings had no effect on infectibility. Natural sutures performed poorly and should not be used in wounds that are potentially susceptible to infection.

Animals↗
PubMed1982

Arterial occlusive disease: a function of vessel bifurcation angle.

A clinical observation that patients with aortoiliac occlusive disease have a high aortic bifurcation serves as the stimulus for this study. A review of 100 consecutive abdominal aortograms revealed that patients with occlusive disease had an average bifurcation angle of 38 degrees and those with normal studies or aneurysmal disease had an average angle of 52 degrees. A flow visualization system was constructed to study shear stress using eight Pyrex models with varying bifurcation angles (20 to 90 degrees). The perfusate consisted of a 35% sucrose solution with anion-exchange beads to serve as flow particles. The bifurcations were photographed at three different flow rates. The length of each tracer particle was measured to determine its velocity. Velocity profile curves were constructed and shear stress calculated by the formula shear stress = mu x dv/dr, where mu is viscosity, v is velocity, and r is radius. Results of the study suggest that more acute angles cause a greater shear stress on the inner wall of the bifurcation and decreased shear stress on the outer wall. Two theories of atheroma predilection, high shear stress and low shear stress, are applied to patients with high acute aortic bifurcations.

Aorta, Abdominal↗
PubMed1981

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.

Adult↗
PubMed1979

Thrombogenic potential of dacron grafts after prior exposure to whole blood, plasma, or albumin.

On hundred forty six (146) vascular graft insertions have been examined to determine the best exposure media, the mode of exposure, and the time of exposure required to change the TP of knitted dacron fabric. Whole blood, plasma, albumin, and Ringer's lactate (as control) were the media used. The mode of exposure was by either simple soaking or physiological perfusion with the appropriate media. The time of exposure was from one hour to 7 days. Simple soaking in species-specific albumin was found to be highly effective in lowering the TP of knitted dacron and we advocate this as the initial step in preclotting dacron grafts. This step is equally critical in the smaller vascular replacements and should lead to improved patency of these dacron vascular grafts.

Animals↗
PubMed1978

Thromboresistance of pyrolytic carbon grafts.

This study reports in vivo testing of ULTI carbon coated dacron grafts in the dog's 4 mm carotid artery, and showed 97.5% patency at 21 days in 40 grafts compared to 33% in 6 control grafts. Physical properties of the dacron substrates were not altered after ULTI carbon deposition. The carbon coated grafts must be carefully cleaned and maintained in that condition. This initial study with the modified pyrolytic carbon adds a new dimension to vascular prosthetics and artificial organ development.

Animals↗
PubMed1978

Pyrolytic carbon-coated Dacron grafts.

A new pyrolytic carbon surface (ULTI) was tested on a loosely knitted dacron substrate in dogs. Patency was 97.5% as compared with a control of 33%. Physical properties of the dacron were not altered by the ULTI carbon deposition process. This modified pyrolytic carbon on a dacron substrate is a very promising vascular biomaterial for small vessel replacement.

Animals↗
PubMed1976

Endothelial-cell development: pressure-flow phenomena.

Scanning electron micrographs showed directional orientation and cytoplasmic changes in the seeded cells after 21 days of perfusion. From this evidence it is theorized that human fibroblasts, exposed to physiological pressures and flows, exhibit morphological characteristics similar to arterial endothelial cells. Conceivably, cells other than fibroblasts (i.e., multipotential cells) would show the same response to these pressure and flow conditions.

Blood Circulation↗