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Biomedical subjects

W S Moore

Publications and source records attributed to W S Moore.

At least 19 recordsLinked to original sources
PubMed1992

Intraoperative peripheral rotary atherectomy: early and late clinical results.

Early and late clinical results of intraoperative peripheral atherectomy using the Auth Rotablator are analyzed. Twenty patients (15 males and 5 females age 39-89 years, mean 70 years) underwent 25 atherectomy procedures for peripheral arterial occlusive disease from August 1987 to October 1989. All patients underwent serial history, physical exam, and Doppler pressure measurements preoperatively and then postoperatively at 24 hours, one week, one month, and six months during a follow-up period of 15 to 41 months, mean 27 months. Preoperative and intraoperative completion follow-up arteriography was done in all cases and follow-up arteriography in 19 of 25 cases. Initial arteriographic success was achieved in 23/25 (92%) cases and in 39/41 (93%) arterial segments (superficial femoral artery 12/13, popliteal 14/15, tibial 12/13, profunda-femoral 1/1). Complications included intimal dissection (1), equipment breakage (2), minor emboli (3), major emboli with thigh skin loss (1), transient hemoglobinuria (4), wound hematoma (1), wound infection (1), and limb loss (1). Early thrombosis occurred in five cases to give an in-hospital success rate of 18/25 (72%). Primary patency was 66% at six months but only 12% at two years. Rotary atherectomy effectively recanalizes femoral, popliteal and tibial arteries. However, early thromboembolic complications occurred frequently, and the two year patency was dismal. Rotary atherectomy is not recommended for general use until problems of thromboemboli and intimal hyperplasia are solved.

Adult↗
PubMed1992

Standardization of skeletal muscle ischemic injury.

Observations on skeletal muscle function after a timed ischemic interval suggests significant interanimal variability. The purpose of this study is to compare the use of function versus time as a method for standardizing the degree of ischemic injury. Muscle function was measured by recording the isometric contraction to direct supramaximal tetanic stimulation of the anterior tibialis muscle (AT). Muscle cell viability was determined by the reduction of triphenyltetrazolium chloride (TTC)/g tissue measured by a spectrophotometric assay. Twenty-four New Zealand White rabbits underwent an interval of ischemia to one anterior tibialis muscle produced by collateral ligation and unilateral inflow control, using the contralateral AT as a control. The duration of ischemia was determined by one of three methods: Group I, n = 8, underwent ischemia for 3 hr (3 hr); Group II, n = 8, underwent ischemia until AT muscle function decreased to 20% of control (20%); and Group III, n = 8, underwent ischemia until AT muscle function decreased to less than 5% of control (less than 5%). Following the ischemic injury, both physiologic function and cellular viability were measured and expressed as a percentage of control. After 3 hr of ischemia, the mean function was 15.5 with a standard deviation of 20.2, and the TTC reduced/g tissue was 24.7 with a standard deviation of 24.8. When the ischemic interval was determined by a decline of muscle function to 20% of control, the mean TTC reduced was 33.4 +/- 7.6. The mean TTC reduced, when the ischemic interval was terminated when muscle function reached less than 5% of control, was 13.5 +/- 7.2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Inhibition of intimal hyperplasia by photodynamic therapy using photofrin.

Photodynamic therapy using photofrin and light energy inhibits human myofibroblast proliferation in cell culture. The purpose of this study is to evaluate its influence on intimal hyperplasia in vivo. Twenty New Zealand White rabbits underwent a standardized intimal injury to both common carotid arteries with a 2 Fr balloon catheter. One week later, half of the animals received photofrin (5 mg/kg) intravenously. The remaining 10 rabbits received no photofrin. Two days later, all neck incisions were reopened and a 1-cm segment of each of the 40 carotid arteries was exposed for 5 min to 80 mW of 630 nm light energy from a continuous wave tunable dye laser (fluence = 7.6 J/cm2). All vessels were harvested 5 weeks post-laser treatment following in vivo fixation with formalin. From each artery, separate cross-sections taken from both the lasered and non-lasered regions of each vessel were mounted and stained for histologic evaluation. Analyzed segments were then divided into four different treatment groups: group I segments consisted of arterial cross-sections which were taken from vessel regions that were injured but received neither photofrin nor laser treatment (group I, n = 20); group II segments also did not receive photofrin but were exposed to light energy (group II, n = 20); group III segments received photofrin but no light energy (group III, n = 20); and cross-sections in group IV were taken from those segments which received both photofrin and laser treatment. Using planimetry, the ratio of the area of intimal hyperplasia (IH) to the area enclosed by the internal elastic lamina (IEL) was measured for each specimen (IH/IEL).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Alteration of neutrophil (PMN) function by heparin, dexamethasone, and enalapril.

The aim of this study is to investigate the effect of a seemingly divergent class of pharmacologic agents, each having been reported to suppress intimal hyperplasia, on neutrophil (PMN) function. Human PMNs were isolated and exposed for 30 min to either saline or one of three different pharmacologic agents, each tested at three different concentrations: Group 1, saline (control, n = 14); Groups 2-4, heparin (5000 units, n = 8; 2500 units, n = 6; 1250 units, n = 6) respectively; Groups 5-7, dexamethasone (4 mg, n = 8; 2 mg, n = 6; 1 mg, n = 6), respectively; and Groups 8-10, enalapril (1.25 mg, n = 8; 0.62 mg, n = 6; 0.31 mg, n = 6). Superoxide anion production was measured by the reduction of cytochrome c in a spectrophotometric assay. Chemotaxis was evaluated by the number of PMNs migrating across a filter using a Neuro Probe chamber. Phagocytosis was determined by the ingestion of opsonized zymosan particles by PMNs. Serum obtained from each PMN donor was used both to opsonize the zymosan and as a chemoattractant in the chemotaxis assay. No agent, at any dose, significantly changed superoxide production when compared to control cells. All three agents significantly inhibited PMN chemotaxis at every dose tested (P less than 0.01). In the phagocytosis assay, both heparin (at high and intermediate doses) and enalapril (at all doses) significantly reduced phagocytic activity (P less than 0.01); however, dexamethasone (at high and intermediate doses) produced a marked stimulation (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Anions↗
PubMed1992

Dose responsive suppression of myointimal hyperplasia by dexamethasone.

The effect of increasing doses of dexamethasone on the development of myointimal hyperplasia in the rabbit carotid artery was studied by use of a balloon catheter injury model. Seventy New Zealand white rabbits underwent a standardized 2F balloon catheter stripping of the left carotid intima. The animals were randomly assigned to one of seven groups, each receiving daily injections of either saline (group I, N = 10) or graded doses of dexamethasone: 0.025 mg/kg (group II, N = 10); 0.050 mg/kg (group III, N = 10); 0.075 mg/kg (group IV, N = 10); 0.100 mg/kg (group V, N = 10); 0.125 mg/kg (group VI, N = 10); 0.150 mg/kg (group VII, N = 10). Injections were started 2 days before the intimal injury and continued daily, five times a week, for 8 weeks. The vessels were harvested 12 weeks after injury, and the ratio of the absolute area of intimal hyperplasia to the normalized area enclosed by the internal elastic lamina was measured as an index of myointimal hyperplasia. Also, at the time of harvest, blood flow (ml/min) was measured and the resistance delta P/flow (mm Hg/ml/min) calculated for each vessel in vivo. Twelve-week patency rates were 60% in the control group I, 90% in groups II and III, and 100% in groups IV, V, VI, and VII. The value for the intimal hyperplasia/internal elastic lamina index, expressed as a percent, was 22.2 +/- 3.7 for control group I, 17.7 +/- 2.1 group II, 14.8 +/- 3.0 group III, 12.8 +/- 2.4 group IV, 11.5 +/- 1.8 group V, 5.4 +/- 1.3 group VI, and 3.9 +/- 1.1 for group VII.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

Heparin, urokinase, and ancrod alter neutrophil function.

Neutrophils (polymorphonuclear neutrophils [PMNs]) have been implicated as mediators of reperfusion injury. Heparin, urokinase, and ancrod are agents used routinely to prevent and treat thrombosis, yet their effects on PMN function are unknown. Therefore human PMNs were obtained and incubated for 30 minutes with either saline solution or one of the following pharmacologic agents, each tested at three different concentrations: group 1, saline solution (control, n = 14); groups 2 through 4, heparin (5000 units/ml, n = 8; 2500 units/ml, n = 6; and 1250 units/ml, n = 6, respectively); groups 5 through 7, urokinase (50,000 units/ml, n = 8; 25,000 units/ml, n = 6; and 12,500 units/ml, n = 6, respectively), and groups 8 through 10, ancrod (70 units/ml, n = 8; 35 units/ml, n = 6; and 17.5 units/ml, n = 6). Superoxide anion production was measured by the reduction of cytochrome c in a spectrophotometric assay. Chemotaxis was evaluated by the number of PMNs migrating across a filter with a Neuro Probe chamber (Neuro Probe, Cabin John, Md.). Phagocytosis was determined by the ingestion of opsonized zymosan particles by PMNs. Serum obtained from each PMN donor was used both to opsonize the zymosan and as a chemoattractant in the chemotaxis assay. Statistical comparison was evaluated by analysis of variance, and post hoc comparisons for each agent with control were performed with the unpaired Student t test. No agent, at any dose, significantly changed superoxide anion production compared with control cells. All three agents significantly inhibited PMN chemotaxis (p < 0.01). In the control group the number of PMNs counted was 27.6 +/- 4.9.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

Use of an antibiotic-bonded graft for in situ reconstruction after prosthetic graft infections.

We have developed an infection resistant vascular prosthesis by bonding rifampin to Dacron grafts with the use of a collagen matrix release system. The purpose of this study was to determine the efficacy of this antibiotic-bonded graft in resisting infection after an in situ reconstruction of a previously infected prosthetic bypass. Eighty-three adult mongrel dogs underwent implantation of a 3 cm untreated Dacron graft into the infrarenal aorta. This initial graft was deliberately infected, at the time of operation, with 10(2) organisms of Staphylococcus aureus by direct inoculation. One week later, the dogs were reexplored, the retroperitoneum debrided, and the animals randomized to undergo an end-to-end in situ graft replacement with either one of two types of prosthetic grafts: group I (collagen, n = 36) received control collagen-impregnated knitted Dacron grafts; group II (rifampin, n = 47) received experimental collagen-rifampin-bonded Dacron grafts. Each group of animals was then subdivided to receive one of four treatment protocols: (a) no antibiotic therapy, (b) cephalosporin peritoneal irrigation solution (cefazolin 500 mg/1000 ml) during operation and two doses of cephalosporin (cefazolin, 500 mg intramuscularly) postoperatively, (c) treatment as in protocol group b plus 1 week of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily), and (d) treatment as in protocol group b plus 2 weeks of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily). All grafts were sterilely removed between 3 and 4 weeks after implantation. There were no anastomotic disruptions and all grafts were patent at the time of removal.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Endovascular surgery for peripheral arterial occlusive disease. A critical review.

Endovascular surgery is a new multidisciplinary field that applies the recently innovated techniques of angioscopy, intraluminal ultrasound, balloon angioplasty, laser, mechanical atherectomy, and stents. This field can be defined as a diagnostic and therapeutic discipline that uses catheter-based systems to treat vascular disease. As such, it integrates the subspecialties of vascular surgery, interventional radiology, interventional cardiology, and biomedical engineering for the common purpose of improving arterial hemodynamics. Endovascular surgery offers many potential benefits: long incisions are replaced with a puncture wound, the need for postoperative intensive care is significantly reduced, major cardiac and pulmonary complications from general anesthesia are side stepped, and the dollar savings could be dramatic as the need for intensive care unit and in-hospital stay diminishes. Despite these technological advancements, endovascular surgery is still in its infancy and currently has limited applications. This review provides an updated summary of endovascular surgery today and addresses some of the obstacles still preventing its widespread use.

Angioplasty, Balloon↗
PubMed1992

Improved prognosis for asymptomatic carotid stenosis with prophylactic carotid endarterectomy.

BACKGROUND AND PURPOSE: The value of carotid endarterectomy in asymptomatic patients with high-grade stenosis is controversial. The objective of this study is to compare the immediate and long-term outcome of patients after carotid endarterectomy for asymptomatic carotid stenosis (greater than 75%) with the reported natural history of patients followed nonoperatively to determine whether carotid endarterectomy reduces the subsequent neurological event rate. METHODS: The data from 141 carotid endarterectomies performed in 123 patients between January 1980 and December 1986 were reviewed from the perspective of perioperative results and long-term follow-up to January 1990, providing a follow-up ranging from 3 to 10 years. The mean follow-up was 56.6 months (range 27-117 months). RESULTS: There were no perioperative deaths. There were two postoperative stokes: one in the cerebellar distribution and one in the middle cerebral distribution. During the course of follow-up, no patient suffered a stroke in the hemisphere ipsilateral to carotid endarterectomy. One patient developed ipsilateral transient ischemic attacks 24 months after surgery associated with carotid restenosis. A total of three patients developed four recurrent carotid stenoses, for an incidence of 2.8%. All four recurrences were corrected surgically. CONCLUSIONS: These findings are in marked contrast to the reported natural history of patients with greater than 75% stenosis in which the 1-year neurological event rate is 18% and the 1-year stroke rate is 5%. Although final proof of efficacy for prophylactic carotid endarterectomy in asymptomatic patients will await the outcome of randomized trials, until these data are available, prophylactic carotid endarterectomy is justified in centers of excellence that can perform the surgery with low perioperative risk.

Adult↗
PubMed1992

Long-term results of infrainguinal revascularization with polytetrafluoroethylene: a ten-year experience.

Two hundred fifty-eight patients underwent 322 infrainguinal revascularizations with use of polytetrafluoroethylene (PTFE) between 1978 and 1988. The indication was limb salvage in 190 (59%) reconstructions. Two hundred nineteen (68%) were above-knee, and 75 (23%) were below-knee femoropopliteal bypasses. Twenty-eight (8.6%) were femoral-infrapopliteal bypasses, all done for limb salvage. Follow-up ranged from 24 to 144 months (mean, 66 months). The perioperative mortality rate (1 to 30 days) was 3.4% (9 patients), with no significant difference according to indication (2.9% vs 3.7%). Actuarial primary patency at 8 years for the entire series of femoropopliteal bypasses was 53% (above knee 53%; below knee 39%; p less than 0.05), and improved with additional procedures for a secondary patency of 72%. Femoropopliteal bypasses done for severe claudication had an 8-year actuarial primary patency of 63%, compared with 38% for limb salvage (p less than 0.02). Actuarial limb salvage in the latter group at 8 years was 66%. Femoral-infrapopliteal reconstructions with PTFE had a significantly lower primary patency at 3 years (22%, with a 37% limb salvage). Sixty-four percent of the failures for all reconstructions (N = 111) occurred within 12 months, with remarkable stabilization of patency curves beyond that interval. This experience represents the largest reported series of PTFE reconstruction with longest follow-up to date and may serve as a basis for comparison of other conduits. These results suggest an important role for PTFE in femoropopliteal revascularization and a limited role of this prosthetic conduit in femoral-infrapopliteal arterial reconstructions.

Adult↗
PubMed1991

Long-term results following surgical management of aortic graft infection.

Between January 1970 and June 1988, a total of 45 patients with aortic prosthetic graft infection underwent removal of the infected aortic prosthesis. In addition, 36 of these patients also underwent revascularization via an extra-anatomic bypass. We analyzed the early and long-term results with respect to survival, limb salvage, freedom from infection, and extra-anatomic graft patency. The 30-day mortality was 24% (11/45), and the amputation rate was 11% (8/73). During a mean follow-up of 36 months (range, 2 to 144 months), 80% (24/30) of the patients remained free of infection and are considered cured. Infection in the extra-anatomic bypass graft was the most common cause of recurrent sepsis and the leading cause of late amputations (four of seven). By life-table methods, 1-year survival was 63% and 5-year survival was 49%. Limb salvage rates at 1 and 5 years were 79% and 66%, respectively. The primary patency rate of extra-anatomic bypass was 43% at 3 years, with the secondary patency rate improved to 65%. These early and late results are in marked contrast to the natural history of untreated aortic graft infection. Nonetheless, a perioperative mortality rate of 24%, a 5-year limb loss rate of 33%, and 3-year graft thrombosis rate of 35% are testimony to the serious nature of aortic graft infection and the need to develop better methods to prevent this complication.

Actuarial Analysis↗
PubMed1991

Failure of PTFE infrainguinal revascularization: patterns, management alternatives, and outcome.

This review identifies the causes of PTFE infrainguinal bypass graft failure and compares the results of management alternatives. In 322 infrainguinal reconstructions 111 failures occurred over a ten year interval (1978-1988). Sixty-four percent of all failures occurred within the first year, most within the first six months due to severity or progression of distal disease (56%), which suggests that patient selection is an important factor. Only 8% of cases had intimal hyperplasia as a cause of failure without evidence of distal disease progression, and all occurred within the first twelve months. Progression of inflow disease occurred in 25% of instances and was most commonly seen as progression of iliac disease in patients operated upon to relieve claudication and thrombosis of inflow reconstructions in limb salvage patients. Infection was the cause of failure in 5.5% of failed grafts (1.8% of the series) and was associated with multiple reoperations. Management consisted of conservative treatment in 15 cases, with amputation resulting in seven (46%) of these. Operative treatment consisted of (A) thrombectomy with or without patch (N = 56); (B) extension with vein (N = 12); (C) replacement with vein (N = 11); or (D) extension or replacement with PTFE (N = 17). Primary patency and limb salvage of secondary procedures at 30 months after the reoperation was (A) 40%/45%; (B) 32%/43%; (C) 55%/72%; and (D) 30%/38%, respectively. Patients in Group C (replacement with vein) had an 88% 30-month patency when this was the first procedure after the failure, with limb salvage in all cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1991

Which asymptomatic patients should undergo routine screening carotid duplex scan?

The benefits of obtaining a routine screening carotid duplex scan have not been established for patients with peripheral vascular disease but no signs or symptoms of carotid artery disease. We retrospectively reviewed all carotid duplex scans (4,000) performed at our institution between 1985 through 1989 and found for analysis 91 scans in 78 patients who underwent a screening duplex scan because of the presence of peripheral vascular disease. Patients with carotid bruits, abnormal carotid pulses, and focal or nonspecific neurologic symptoms were excluded. Thirty-three percent of these patients had carotid stenosis of 16% to 50%, 14% had carotid stenosis greater than or equal to 50%, and 5% had stenosis greater than or equal to 75%. Individual risk factors for atherosclerosis, including elderly age, coronary artery disease, hypertension, diabetes, smoking, and a recent or past history of cardiac or vascular surgery, did not predict the detection of high-grade carotid stenosis. However, all 11 of the patients with carotid stenosis greater than or equal to 50% were 68 years of age and older, and this age range, in combination with the various risk factors, increased the incidence of significant carotid artery stenosis (greater than or equal to 50%) to as high as 45%. We conclude that routine screening carotid duplex scan is indicated in elderly patients (age greater than or equal to 68 years) with peripheral vascular disease, even in the absence of any signs or symptoms of carotid artery disease, when other atherosclerotic risk factors are present.

Adult↗
PubMed1991

Skeletal muscle function after ischemia: "no reflow" versus reperfusion injury.

The isometric contraction (supramaximal tetanic stimulation) of anterior tibialis muscle was studied in 32 New Zealand white rabbits after 5 hr of ischemia. Reperfusion was achieved after systemic heparinization (100 U/kg) by removal of vascular clamps (normal reperfusion, NR, N = 10); isolated pump perfusion at 15 cc/min for 30 min followed by normal reperfusion (controlled reperfusion, CR, N = 8); CR with a Sepacell 500 filter in the circuit (leukopenic, thrombocytopenic, controlled reperfusion, L/TR, N = 9); or adding 25,000 U of urokinase to the initial reperfusate (UKR, N = 5). Experimental muscle is compared to control nonischemic contralateral muscle in each animal and expressed as percentage of control function. Specimens were studied by light microscopy. No significant difference in mean function at 2 hr was seen between the four groups, with NLR having 53% of control function, CR 55% of control function, L/TR 61% of control function, and UKR 48% of control function. "No reflow," as defined by the absence of Doppler flow signals over the muscle pedicle with no recovery of function during reperfusion and continued incidence of persistent ischemia, was seen in NLR 4/10, CR 5/8, and L/TR 6/9 preparations with arteriolar, capillary, and venule thrombi documented by light microscopy. In contrast, "no reflow" was not seen in UKR (0/5, P less than 0.05). Peak function at any interval (potential maximal recovery) in muscles that adequately reperfused was best in CR (73%) and L/TR (73%). No difference in the degree of injury in adequately reperfused muscles was seen between the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗