Richard F. Kempczinski

Kinetics of endothelial cell seeding

Endothelial cell seeding improves patency of small-diameter Dacron grafts and facilitates the development of a complete endothelial flow surface. However, the ideal number of cells relative to the length of graft to be seeded has not been determined. With a canine model previously shown to result in a well-endothelialized graft within 4 to 6 weeks, this study measured the quantity of autogenous endothelial cells labeled with indium 111-oxine that initially adhered to 10 cm long, experimental, porous 4 mm I.D. polytetrafluoroethylene grafts and then calculated their subsequent disappearance following implantation as carotid interposition grafts. Graft radioactivity was monitored with a gamma camera and compared with that of control vials of indium 111 implanted in the same animals. Counts were measured immediately at implantation and for up to 72 hours following restoration of flow. Data were analyzed by linear regression. The mean number of harvested endothelial cells was 6.2 X 10(5). A mean of 19.8% of the harvested cells were adherent to the grafts initially after seeding. In the first 30 minutes following restoration of flow, there was a rapid loss of these cells to a mean value, which was 70.2% of those initially present. From 30 minutes to 24 hours, cell losses continued at a constant rate of 3.7%/hr (r = -0.922, p less than 0.001). Beyond 24 hours, further loss was insignificant. Consequently, approximately 2.72 X 10(4) cells, or only 4.4% of all cells originally harvested, appear adequate to seed 12.5 cm2 of graft.(ABSTRACT TRUNCATED AT 250 WORDS)

Suggested standards for reports dealing with cerebrovascular disease

The evaluation of clinical reports on vascular disease is often made difficult by variations in descriptive terms, clinical classification, and outcome criteria. In 1983 the Joint Council of the Society for Vascular Surgery and the North American Chapter of the International Society for Cardiovascular Surgery created the Ad Hoc Committee on Reporting Standards to address these problems and recommend solutions. Some general problems were addressed in the initial report dealing with lower extremity ischemia. This article concerns clinical standards for reports dealing with cerebrovascular disease, suggests a scheme for clinical classification, and recommends standardized reporting practices for grading risk factors, angiographic and other diagnostic findings, and the results and complications of therapeutic intervention.

The effect of fibronectin coating on endothelial cell kinetics in polytetrafluoroethylene grafts

Despite the proven experimental success of endothelial cell seeding of prosthetic vascular grafts, the process has not been widely accepted for clinical use because of its complexity and the need for a relatively large length of autologous vein to provide the requisite number of cells. Using autologous endothelial cells radiolabeled with indium 111-oxine, we studied the effect of fibronectin coating of polytetrafluoroethylene grafts in a canine carotid interposition model on initial endothelial cell adherence and subsequent cell retention for up to 72 hours following restoration of blood flow. Since the number of harvested endothelial cells varied widely depending on the diameter and length of available vein, cellular adherence was best expressed as a percentage of the original cell harvest. More than twice as many (46.7% vs. 19.8%) endothelial cells initially adhered to fibronectin-coated grafts compared with uncoated control grafts. Fibronectin did not appear to influence the loss of cells within the first 30 minutes following restoration of blood flow. However, over the next 24 hours, it clearly reduced the mean cell loss from 3.7%/hr to 2.2%/hr and resulted in a sixfold increase (21.3% vs. 3.4%) in the number of retained cells at the end of a 24-hour period. When the endothelial cell preclot was performed with a solution of culture medium 199, as opposed to heparinized whole blood, there was no significant difference in endothelial cell retention.(ABSTRACT TRUNCATED AT 250 WORDS)

Endothelial cell seeding of a new PTFE vascular prosthesis

Previous attempts to line polytetrafluoroethylene (PTFE) prostheses with enzymatically derived endothelial cells have not been as successful as similar work with Dacron grafts because of the failure of such prostheses to develop a satisfactory subendothelium. This article reports our experience with a new, highly porous, unreinforced PTFE prosthesis that appears to circumvent this problem. Segments (4 mm I.D., 10 cm in length) of this new graft were implanted in 41 mongrel dogs as carotid interposition grafts. One graft in each dog was seeded with the dogs own endothelial cells, whereas the contralateral graft was treated in an identical fashion except for the inclusion of endothelium. After a mean period of 7 weeks of implantation, the grafts were harvested, their patencies were noted, the thrombus-free area of their luminal surface was calculated with computerized quantitative planimetry, and graft segments were submitted for scanning and transmission electron microscopy. In seven dogs the luminal surface was scraped from each graft and measured quantitatively. Although seeded grafts failed to show a statistically significant increase in patency during the short course of this experiment, a trend in that direction was quite striking. Furthermore, seeded grafts had a significant increase in thrombus-free area on their luminal surface as well as a significant reduction in the volume of luminal thrombus. Histologically, seeded grafts developed a substantial 75 to 100 microns cellular subendothelium beneath a confluent endothelial lining. No endothelial lining was noted in control grafts. We believe that the superior handling characteristics of this new prosthesis and its ability to develop a substantial subendothelium with a confluent endothelial lining suggest potential future applications and warrant further investigation.

The influence of surgical specialty and caseload on the results of carotid endarterectomy

Carotid endarterectomy is rapidly becoming one of the most commonly performed major surgical operations in the United States, in part because of the greater availability of noninvasive techniques to accurately diagnose extracranial carotid arterial disease and a low reported morbidity and mortality. We retrospectively reviewed the records for all carotid endarterectomies performed in the greater Cincinnati area for a recent 12-month period and examined the impact of surgical specialty and operative caseload on the results. Altogether, 750 operations were performed on 656 patients by 61 surgeons working in 16 general medical-surgical hospitals. Overall, strokes occurred in 5.1% of all patients; 2.3% of patients died. Symptomatic patients had a significantly higher risk of suffering a postoperative stroke compared with asymptomatic patients (6.5% vs. 3.7%), although the risk of death was virtually identical (2.4% vs. 2.1%). When the operating surgeons were classified into four types on the basis of their previous training, no statistically significant differences in either postoperative stroke or death could be identified. Furthermore, when the surgical caseloads of these physicians were grouped into three categories (i.e., less than 12 each year, more than 50 each year, and a group between these two extremes), no significant differences in outcome were seen. We concluded that our community-wide results for carotid endarterectomy were not comparable to those previously published from specialized centers and that these results did not appear to be influenced by the type of formal surgical specialty or operative caseload.

Role of the vascular diagnostic laboratory in the evaluation of male impotence.

Penile systolic pressures, penile volume waveforms, and postischemic reactive hyperemia were measured in 106 patients (38 potent and 68 impotent). With such testing the vascular laboratory can clearly identify those impotent patients in whom penile blood flow is normal and who would not benefit from direct arterial surgery. Unfortunately, abnormal results give no assurance that ischemia is responsible for a given patients impotence and a multimodal approach is necessary to further evaluate such patients.

Impact of endothelial cell seeding on long-term patency and subendothelial proliferation in a small-caliber highly porous polytetrafluoroethylene graft * **

Previous reports have demonstrated that endothelial cell seeding of polytetrafluoroethylene (PTFE) grafts enhances short-term patency. This experiment was undertaken to study its impact on the long-term patency of a highly porous, experimental PTFE graft and to determine whether increasing the internodal distance of the graft material resulted in increased proliferation of the subendothelium. Ten centimeter long, 4 mm internal diameter segments of an unreinforced, experimental PTFE graft were implanted into 36 mongrel dogs as carotid interpositions. In each animal, one graft was seeded with autologous endothelial cells, enzymatically derived from the external jugular veins, whereas the contralateral graft was treated in identical fashion except that endothelial cells were not added to the preclot mixture. Nineteen animals were killed at 12 weeks; six at 22 weeks; eight at 26 weeks; and three at 52 weeks. The mean follow-up period was 20.1 weeks. The overall patency rate was 58.3% (21 of 36 grafts) for seeded grafts vs. 27.8% (10 of 36 grafts) for control grafts (p less than 0.01). The thrombus-free area was planimetrically measured at 83.4% +/- 4.5% in seeded grafts vs. 55.1% +/- 9.7% in control grafts (p less than 0.05). Scanning electron microscopy confirmed the presence of a confluent cellular monolayer in seeded grafts, whereas control grafts exhibited a variable coagulum of fibrin, platelets, and endothelial cells. The thickness of the subendothelial layer varied from 56 to 95 micron with no progressive increase in thickness between 12 and 52 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial adherence to vascular grafts after in vitro bacteremia

All currently used arterial prosthetics have a greater susceptibility to infection following bacteremia than does autogenous tissue. This experiment compares quantitative bacterial adherence to various prosthetic materials after bacteremia carried out in a tightly controlled and quantitative fashion. Ten centimeters long, 4 mm i.d. Dacron, umbilical vein (HUV), and polytetrafluoroethylene (PTFE) grafts, as well as PTFE grafts with a running suture line at the midportion were tested. Each graft was interposed into a pulsatile perfusion system modified from a Waters MOX 100 TM renal transplant pump. Indium-111-labeled Staphylococcus aureus were added to heparinized canine blood to give a mean concentration of 4.7 X 10(6) bacteria/cc. This infected blood was recirculated through each graft for 30 min at a rate of 125 cc/m, 100 Torr (sys), 60 beats/min. The gamma counts/graft were used to calculate the number of bacteria/cm2 of graft surface. After nine experiments, a mean of 9.63 X 10(5) bacteria/cm2 were adherent to the Dacron, 1.04 X 10(5) bacteria/cm2 to the HUV, and 2.15 X 10(4) bacteria/cm2 to the PTFE. These differences were all significant at the 0.05 level. The addition of a suture line increased bacterial adherence to the PTFE graft by 50%. These results suggest that PTFE is the vascular graft material of choice when a prosthetic graft must be implanted despite a high risk of subsequent clinical bacteremia. Our in vitro, pulsatile perfusion model gave accurate and reproducible results, and appears well suited for further studies of bacterial, or platelet adherence to grafts, as well as the biomechanics of vascular conduits.

Surveillance venous scans for deep venous thrombosis in multiple trauma patients

The high reported incidence of deep venous thrombosis (DVT) in trauma patients has prompted surveillance venous duplex scanning of the lower extremities. We report our retrospective experience with 183 multiple trauma patients who were admitted to the surgical intensive care unit and underwent 261 surveillance venous scans. There were 122 men and 61 women whose average age was 38 years. All patients were treated prophylactically with either extremity pneumatic compression or subcutaneous heparin to prevent DVT. Most (87%) patients suffered blunt trauma and had either head (3%), spinal (3%), intra-abdominal (9%), or lower extremity (17%) injuries or a combination of injuries (68%). Almost two thirds of the patients had no symptoms suggestive of possible DVT. Of the 261 venous scans performed, 239 (92%) were normal, 16 (6%) were positive for proximal lower extremity DVT, and six (2%) showed thrombus limited to the calf veins. Patients with symptoms of lower extremity DVT were significantly more likely to have proximal DVT compared to those without symptoms (15% vs. 5%,p <0.05).Patients with spinal injuries also had a higher incidence of proximal DVT (18% vs. 6%,p <0.05).At current hospital charges, the cost to identify each proximal DVT was

Mycotic aneurysm of the tibioperoneal trunk: Case report and review of the literature

6688. If surveillance duplex scans were performed on all trauma patients in the surgical intensive care unit, the national annual expense would be