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Biomedical subjects

W S Moore

Publications and source records attributed to W S Moore.

At least 109 records · Page 6Linked to original sources
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↗
PubMed1991

Efficacy and duration of antistaphylococcal activity comparing three antibiotics bonded to Dacron vascular grafts with a collagen release system.

Type 1 collagen, minimally cross-linked, was used to bind one of three antibiotics (amikacin, chloramphenicol, or rifampin) to double-velour Dacron grafts to develop a prosthesis resistant to infection. Six millimeter disks of graft were placed in separate flasks (specific for each antibiotic) containing albumin in saline and continuously agitated. At daily intervals the solution was changed, and paired graft samples were removed and placed on a blood agar plate confluently streaked with bacteria. The initial zone of inhibition (centimeters squared), the time to 50% reduction of initial inhibition zone, and the overall duration of antibacterial activity were recorded on an exponential model. Grafts bonded with amikacin and chloramphenicol had an overall duration of activity of only 2 and 1 day, respectively, against Staphylococcus aureus. The collagen bonded rifampin grafts had an initial zone of 14.76 cm,2 took 3.92 days to reach 50% of initial inhibition, and had an overall duration of activity of 22.4 days. This was significantly better than grafts preclotted with 1.0 ml of rifampin (60 mg/ml) and 9 ml of blood (10.92 cm,2 1.06 days, and 5.6 days). When tested against a slime-producing Staphylococcus epidermidis (American Type Culture Collection No. 35983), the graft bonded with rifampin had inhibitory activity of up to 27.77 days with a 50% of activity eluted at 4.78 days, significantly better than the preclotted rifampin graft without collagen bonding. These data suggest that rifampin bonded by collagen can protect a vascular graft against infection from S. aureus and S. epidermidis for up to 3 weeks after implantation.

Amikacin↗
PubMed1991

Selection process for surgeons in the Asymptomatic Carotid Atherosclerosis Study.

BACKGROUND AND PURPOSE: The Asymptomatic Carotid Atherosclerosis Study is a prospective, multicenter, randomized clinical trial of carotid endarterectomy for the treatment of asymptomatic hemodynamically significant stenosis. This report describes the selection process for participating surgeons in the trial. METHODS: The Surgical Management Committee established guidelines for minimal annual experience and maximum neurological morbidity and mortality for surgeons to qualify to participate in the study. For approval, a surgeon must perform at least 12 carotid endarterectomies per year. Based on a review of the surgeon's last 50 consecutive endarterectomies, the combined neurological morbidity and mortality rate must be no greater than 5% for all indications and no greater than 3% for endarterectomies performed on asymptomatic patients. RESULTS: One hundred sixty-four surgeons from 48 centers applied for approval: 117 were approved, 17 were rejected, and 30 were not reviewed. The 117 approved surgeons submitted a total of 5,641 endarterectomies with a combined mortality and neurological morbidity rate of 2.3% for the variety of indications for operation. CONCLUSIONS: This overall experience with carotid endarterectomy is one of the largest series reported to date. The data from approved surgeons are well within the range of acceptable neurological morbidity and mortality rates recommended by the Stroke Council of the American Heart Association, which attests to the overall quality of the surgeons participating in the study.

Carotid Artery Diseases↗
PubMed1991

Biphasic striatal dopamine release during transient ischemia and reperfusion in gerbils.

To clarify the nature of ischemic striatal dopamine release during the earliest periods of neuronal injury, we used chronoamperometry to measure dopamine levels every 60 seconds during various durations of ischemia in 32 gerbils. Catecholamine-selective electrodes were implanted into the brains of anesthetized gerbils subjected to 2, 5, or 10 minutes of transient forebrain ischemia or permanent forebrain ischemia. Four control animals showed a stable chronoamperometric baseline. In the six gerbils subjected to permanent ischemia, dopamine release was rapid during early ischemia and slowed with time. The four animals subjected to 2 minutes of ischemia showed minimal dopamine release. The six gerbils subjected to 5 minutes of ischemia demonstrated a noticeable dopamine release during ischemia, and three of the six developed a massive secondary dopamine release during reperfusion. All six animals subjected to 10 minutes of ischemia demonstrated a similar biphasic dopamine release twice the size of that observed in the 5-minute group. Pretreatment with pargyline in six additional gerbils subjected to 10 minutes of ischemia failed to modify significantly this biphasic pattern of dopamine release. We conclude that dopamine release occurs very early during ischemia and that its magnitude correlates with the duration of an ischemia insult. Reperfusion is associated with an even larger striatal dopamine release. This previously unreported biphasic dopamine release phenomenon may have important clinical implications in the management of cerebral ischemia.

Animals↗
PubMed1991

Prevention of graft infection by use of prostheses bonded with a rifampin/collagen release system.

The objective of this study was to test the efficacy of bonding rifampin to double-velour Dacron grafts with collagen to prevent graft sepsis. Fifty 6.0 mm Dacron grafts (length 5.0 cm) impregnated with either collagen (control) or collagen plus rifampin (experimental) were implanted in dogs end-to-end into the infrarenal aorta. The dogs were divided into four groups (each with an experimental and control subdivision) as a function of time between grafting and bacterial challenge. At 2, 7, 10, or 12 days after graft implantation, sequential groups were challenged with 1.2 x 10(8) colony forming units of Staphylococcus aureus (clinical isolate) intravenously suspended in 250 ml normal saline. Three weeks after hematogenous seeding, the grafts were sterilely harvested. One-tailed Fisher's exact test was used to compare the patency and culture-proven infection of control and antibiotic coated grafts as a function of implantation time before bacteremic challenge. In the 2-day group, four of six control grafts were infected compared with zero of six experimental grafts (p less than 0.030). In the 7-day group, five of six control grafts were infected with S. aureus versus zero of six in the experimental group (p less than 0.008). In the 10-day group, one of six experimental grafts was infected, but the control group had only two of six graft infections. In the 12-day group two of six experimental grafts and one of five control grafts were infected. These results indicate that rifampin bonded with collagen to knitted Dacron grafts will protect the graft from bacteremic infection for 7 days after implantation in a highly challenging model.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗