Search PubMed⌕ Search

Biomedical subjects

W S Moore

Publications and source records attributed to W S Moore.

At least 127 records · Page 7Linked to original sources
PubMed1991

Reducing the risk of stroke: identifying patients to refer for carotid endarterectomy.

The most common causes of stroke are two diseases of aging: hypertension and atherosclerosis. Therefore, although stroke may occur at any age, the incidence is highest among the elderly population. Noninvasive efforts to reduce the risk of stroke in the elderly include control of hypertension and diabetes, smoking cessation, low-cholesterol dietary habits, and moderate exercise. Routine low-dose aspirin also provides some protective effect. High-risk patients (with asymptomatic high-grade stenosis, TIAs, or prior stroke) should be considered candidates for carotid endarterectomy in the absence of contraindications to surgery.

Arteriosclerosis↗
PubMed1991

An argument against all-autogenous tissue for vascular bypasses below the inguinal ligament.

1. Femoropopliteal bypass, regardless of the conduit used, has a 5-year failure rate. 2. The majority of patients with initial reconstruction failure will require secondary repair. 3. Recognition of the ultimate need for secondary repair justifies a long range planning approach for the management of patients who require femoropopliteal reconstruction. 4. Secondary repairs have a dramatically higher patency rate when performed with autogenous saphenous vein than they do with PTFE grafts. 5. Patients who had the initial operation performed with PTFE will have autogenous saphenous vein available for secondary repair, in contrast to the patients who had saphenous vein used in the initial operation; they must rely upon second-best choices including amputation. 6. The greatest and longest term of effective palliation, relief from disabling claudication, or limb salvage will be achieved when PTFE is used preferentially for the first femoropopliteal reconstruction. In the majority of patients, this will be the only operation necessary; they will have had a simple operation, requiring a short period of time, and probably reduced hospitalization. For those who require secondary repair, autogenous saphenous vein is available for that purpose and will yield the best long-term results in comparison to the other alternatives including amputation. Thus, the concept of staged infrainguinal repair using first PTFE and, if necessary, saphenous vein for the secondary repairs provides the longest term palliation for patients with lower extremity arterial occlusive disease.

Arterial Occlusive Diseases↗
PubMed1990

Carotid endarterectomy without angiography.

Carotid endarterectomy without preoperative angiography is a viable alternative that avoids the risk of angiography and potentially reduces the overall morbidity and mortality associated with the workup of patients with carotid artery disease and surgical management. The success of this approach is dependent upon the accuracy of the history and physical examination, acquisition of a CT head scan, and the validity of the duplex scan in a given laboratory.

Carotid Arteries↗
PubMed1990

Histologic and morphologic effects of rotary atherectomy on human cadaver arteries.

Intimal splitting and medial dissection caused by balloon angioplasty and thermal burns and subintimal vacuolization caused by laser angioplasty have been proposed as potential causes of failure from these respective procedures. The purpose of this study was to evaluate the histologic and morphologic effects of a new high speed rotary atherectomy device (the Rotoblator) on human cadaver arteries. Fifteen stenotic human cadaver superficial femoral and popliteal arteries were harvested and atherectomized using the Rotoblator. Histologically, on cross-section, the atherectomized arteries exhibited a denuded endothelial layer, a smooth rounded luminal contour, minute plaque separation from the media, absence of plaque fragmentation, and variable remaining rim of atheromatous plaque. The media showed variable loss of the internal elastic lamina, normal remaining elastin, and normal smooth muscle cells. The adventitia was normal and completely intact in all sections with no media/adventitia separation or perforations. Scanning electron microscopy revealed endothelial peeling, etching from the atherectomy devices within the smooth muscle layer, and a tapered atherectomy distal endpoint. The arterial branches were preserved without evidence of any disruption of the branch artery orifice. Compared to balloon angioplasty and laser angioplasty, the Rotoblator atherectomy device appears to leave a smoother, more rounded luminal surface that may result in less risk of embolic complications and arterial wall damage.

Angioplasty, Balloon↗
PubMed1990

Clinical experience with a collagen-impregnated knitted Dacron vascular graft.

This report describes our first clinical experience with collagen-impregnated Dacron grafts in the aortic position. Fifty-four consecutive patients (43 men and 11 women), average age 67.5 years (44-84), received 11 tube grafts and 23 bifurcated grafts for abdominal aortic aneurysm replacement, 17 bifurcated grafts for aortic occlusive disease, two grafts for aortic pseudoaneurysm, and one graft for thoracoabdominal aneurysm repair. No preclotting maneuvers were used and there was no blood leak from the fabric upon restoration of blood flow, in spite of the use of systemic heparin. The hospital transfusion rate averaged 1.2 units in patients with occlusive disease and 2.7 units in patients undergoing aneurysm resection, which were similar to the transfusion rate in patients receiving standard knitted grafts prior to this study. There were two postoperative deaths from a myocardial infarction and a cerebral hemorrhage and no perioperative thromboembolic events. During a follow-up averaging 41.5 months (26-59), there were two late graft limb thromboses secondary to outflow disease progression. One patient died of aspiration two months postoperatively. Four patients died secondary to cardiac disease in at 13 and 21 months with functioning grafts. The rest of the patients are alive with functioning grafts. We conclude that the collagen-impregnated Dacron graft obviates the need for preclotting maneuvers because of a zero functional porosity.

Adult↗
PubMed1990

Etiologic importance of the intimal flap of the external carotid artery in the development of postcarotid endarterectomy stroke.

A technically unsatisfactory end point (transition from the removed diseased plaque to normal distal intima) leading to an intimal flap of the external carotid artery has been identified as a source of perioperative stroke. The mechanism involves thrombus formation with retrograde propagation of the thrombus and subsequent embolization of the internal carotid artery. This report describes three cases illustrating this mechanism and methods of identification and correction. This mechanism of postoperative stroke adds further justification for the routine use of intraoperative surveillance studies to document the technical result of endarterectomy involving the internal and external carotid arteries. When an unsatisfactory end point is identified in the external carotid artery, it should be corrected with the same sense of concern as a similar finding in the internal carotid artery.

Aged↗
PubMed1990

Diagnosis and management of patients with asymptomatic carotid artery bruit.

Asymptomatic lesions cause approximately 150,000 strokes in the U.S. each year. Lesions associated with significant risk of stroke include atherosclerotic plaques of the carotid bifurcation that compromise the lumen of the internal carotid artery by 75% or more, particularly if the plaque consists of soft material. A group of individuals with significant risk are those with atherosclerotic plaques containing large ulcerations. The risk of carotid endarterectomy is lower for patients with critical lesions that are asymptomatic than for patients with any other surgical indication, and averages a combined risk of morbidity and mortality of less than 1%. Two randomized, prospective studies are currently underway to compare the risks and the benefits of medical and of surgical management of this disease. Until the results of the randomized studies are available, prophylactic carotid endarterectomy for critical lesions is justified if the risk of surgery in the hands of an individual surgeon is less than 3% combined morbidity and mortality.

Arterial Occlusive Diseases↗
PubMed1990

An overview of intimal hyperplasia.

Many hypotheses have been postulated for the development of intimal hyperplasia in vein and prosthetic grafts. In these hypotheses, the central theme seems to be endothelial injury, but not always denuding injury. As we progress into the biologic era with more sophisticated research tools, the study of the endothelial cell may give us the answers to the problem of intimal hyperplasia. In addition, the leukocyte is still a relatively unknown entity and further modification of their function may hold promise.

Animals↗
PubMed1990

Retrograde aortic dissection with bilateral renal artery occlusion after repair of infrarenal aortic aneurysm.

After aortic aneurysmectomy, early postoperative anuric renal failure developed when a retrograde aortic dissection occluded both renal arteries in a 71-year-old woman. Preoperative renal function was retrieved by use of prompt angiography and reconstruction. We are aware of no other reports describing retrograde aortic and bilateral renal artery dissection after aortic aneurysm repair. The case is presented to call attention to this unusual complication and to provide a discussion of acute postoperative renal failure and recommendations for the management of the described complication.

Acute Kidney Injury↗
PubMed1989

Differential recovery of skeletal muscle and peripheral nerve function after ischemia and reperfusion.

Recovery of skeletal muscle function is of prime importance in revascularization of acutely ischemic extremities. In order to study the effect of ischemia and reperfusion on peripheral nerve and skeletal muscle function, temporary unilateral hindlimb ischemia (1 or 3 hr) was induced in 12 rabbits by temporary arterial occlusion of common iliac and femoral arteries and collateral ligation. The control limb was similarly prepared without interruption of blood flow. Both anterior tibialis muscles were attached to force transducers, and the twitch and tetanic tensions were measured at the end of the ischemic interval and during reperfusion (2 hr) by either direct muscle stimulation or stimulation of the deep peroneal nerve. The ischemic limb was reperfused by removal of arterial clamps and reperfusion documented by Doppler flow over the vascular pedicle. The recovery of muscle function of the ischemic/reperfused limb relative to that of the contralateral control limb was used as the index of recovery. By the end of the ischemic interval, no contractile activity was elicited with nerve stimulation for either the 1- or the 3-hr group. After 2 hr of reperfusion, the 1-hr group regained 0.558 +/- 0.116 (mean +/- SEM) of control function with nerve stimulation, while the 3-hr group regained only 0.016 +/- 0.005 of control function (P less than 0.01). In contrast, with direct muscle stimulation, the 1-hr group produced 0.580 +/- 0.015 compared to 0.286 +/- 0.042 (P less than 0.001) after 3 hr of ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Efficacy of corticosteroids in suppression of intimal hyperplasia.

The effect of steroids and immunosuppression on the development of intimal hyperplasia was studied in 24 New Zealand white rabbits. Staged bilateral arteriotomy and stripping of intima of the common carotid artery was performed by means of a 2F balloon catheter under 700 mm Hg of pressure. At 3 months, after the control side artery was harvested (N = 24), the rabbits were assigned to three groups of eight animals each: (1) dexamethasone 0.1 mg/kg, (2) cyclophosphamide (Cytoxan) 1 mg/kg, or (3) azathioprine 1 mg/kg intramuscularly. The animals were treated on the day before the contralateral intimal stripping and then were treated six times a week for 8 weeks; the vessels were harvested at 3 months. Twelve-week patency rates were 62.5% in the control group, 83.3% in the dexamethasone group, 100% in the Cytoxan group, and only 33.3% in the azathioprine group. The ratio of the luminal area to the area enclosed by the internal elastic lamina was used as an index of intimal hyperplasia, with a higher ratio indicating less intimal thickening. This ratio of the patient vessels was 0.74 +/- 0.14 (N = 15) for the controls, 0.79 +/- 0.11 (N = 6) for the Cytoxan group, and 0.91 +/- 0.06 (N = 5, p less than 0.05) for the dexamethasone group, which is statistically significant by means of analysis of variance. Occluded vessels had evidence of organized thrombus without any intimal hyperplasia. The decrease in intimal hyperplasia seen in the steroid group suggests a potential role for steroids in small vessel revascularization, but further studies are required.

Animals↗
PubMed1989

Guidelines for hospital privileges in vascular surgery.

This is a report by an ad hoc committee to the Joint Council of the Society for Vascular Surgery and the International Society for Cardiovascular Surgery (North American Chapter) concerning guidelines that hospitals may use or modify when judging individual applicants for hospital and operating room privileges in vascular surgery. The committee recognizes that the completion of training and obtaining a board certificate is testimony to the qualification but not necessarily the competence of an individual to practice vascular surgery. This report identifies three categories of applicant for privileges in vascular surgery; the surgeon who just completed training, the surgeon who completed training after 1984, and the surgeon who completed training before 1984. In addition, the committee recognizes the importance of periodic vascular surgery privileges renewal for established surgeons. Several pathways are defined for use by hospital privilege committees to evaluate the competence of an individual to be granted privileges in general vascular surgery. The ad hoc committee also has outlined a program for evaluation of established surgeons for renewing privileges in vascular surgery using a mechanism of case outcome audit. Finally, a review mechanism, potential corrective actions, and an appeals mechanism are also suggested. This report represents optimal criteria that may require modification by individual hospitals to meet local community needs and standards. It is the hope of the ad hoc committee that this report will help hospitals and practicing physicians improve the quality of care and treatment outcome in patients with vascular disease.

Credentialing↗
PubMed1989

Post-carotid endarterectomy hypertension: association with elevated cranial norepinephrine.

The cause and mechanism of post-carotid endarterectomy hypertension remains unknown. To determine the influence of the sympathetic and renin-angiotensin system, we measured cranial and peripheral plasma levels of catecholamine and renin in patients undergoing carotid endarterectomy. Baseline samples were drawn just before carotid clamping (sample I) and compared with study samples drawn immediately after clamp release (sample II), 2 to 6 hours after surgery (sample III), and then 18 to 24 hours after surgery (sample IV). The patients with post-carotid endarterectomy hypertension had an associated increase of cranial and peripheral norepinephrine levels in the postoperative hypertensive period whereas the patients without post-carotid endarterectomy hypertension did not. This association was most pronounced and statistically significant in cranial samples II (p = 0.032) and III (p = 0.005). Epinephrine and dopamine values did not correlate with post-carotid endarterectomy hypertension. Renin values were higher in cranial than in peripheral samples at time period 2 (p = 0.011), suggestive of a central nervous system Goldblatt phenomenon. However, the renin values did not correlate with post-carotid endarterectomy hypertension. We conclude that post-carotid endarterectomy hypertension is associated with elevated cranial norepinephrine levels, suggestive of a central nervous system sympathomimetic mechanism. Optimal prevention and treatment of this brief but frequently occurring hypertension should include a central-acting sympatholytic agent.

Aged↗
PubMed1989

Assessing risk associated with carotid endarterectomy. A statement for health professionals by an Ad Hoc Committee on Carotid Surgery Standards of the Stroke Council, American Heart Association.

This position statement provides guidelines for assessing risk associated with carotid endarterectomy and defines the point at which risk is too high to perform surgery for specific indications described below. Morbidity and mortality levels are discussed. This statement does not address indications for surgery or merits of specific medical or surgical treatments. Results of current studies that compare relative risk of various treatments for carotid artery disease are not yet available.

Brain Ischemia↗
PubMed1989

Intraoperative infusion of lytic drugs for thrombotic complications of revascularization.

Between August 1983 and December 1987, 23 patients received a 30-minute intraoperative, intraarterial infusion of streptokinase (seven patients) or urokinase (16 patients) because of residual thrombus or persistent ischemia or both after thromboembolectomy. Ages ranged from 21 to 77 years (mean, 58 years). In 15 patients intraoperative lytic therapy was part of the initial operation, whereas in eight patients intraoperative lytic therapy was performed during a secondary operation to treat thrombosis of a recently placed graft. Seven patients in the latter group had hypercoagulable conditions (five had heparin-induced thrombosis; one had protein C deficiency; one had polycythemia with thrombocytosis). Improvement after intraoperative lytic therapy was seen on angiography performed after infusion in 13 of 17 (76%) patients in whom angiography was performed both before and after intraoperative lytic therapy. Grafts in 12 of these patients remained patent without additional intervention, and in one graft thrombus formed again. In contrast, among four patients without angiographic evidence of improvement, thrombus formed again in four grafts (p less than 0.004). Intraoperative lytic therapy was considered successful in 74% of instances (17/23), including four of seven patients with hypercoagulable states. Three of six patients whose grafts failed had major amputations, whereas there were no amputations after successful infusions. Twelve patients were heparinized after intraoperative lytic therapy. Ten patients in this group were considered treatment successes, and two were considered treatment failures. Three of 11 patients not heparinized after intraoperative lytic therapy were considered treatment failures. Four hematomas occurred in the former group and none in the latter (p less than 0.03). No hematomas occurred in the heparin-induced thrombosis group in spite of anticoagulation with sodium warfarin (Coumadin). Only one hematoma occurred within 6 hours of intraoperative lytic therapy, and thus it was attributable to the infusion. We conclude that intraoperative lytic therapy is an effective adjunct to manage residual thrombus or persistent ischemia or both after lower extremity revascularization. Postinfusion angiography is of prognostic value. Heparinization after intraoperative lytic therapy seems beneficial but significantly increases the risk of bleeding complications.

Adult↗
PubMed1988

Cost of treating advanced leg ischemia. Bypass graft vs primary amputation.

We compared the hospital costs of 94 patients undergoing femoropopliteal bypass grafts with those of 53 patients undergoing primary amputation. The total cost of uncomplicated bypass surgery averaged +20,300, compared with +14,000 for uncomplicated below-knee amputation. However, including the cost of prosthesis and rehabilitation, the total cost of primary amputation was +20,400, equivalent to that of the bypass operation. Complications requiring revision of a bypass graft increased hospitalization by 4.5 days with the total cost rising to +28,700; complications that ended with major amputation added 15 hospitalization days and had an average cost of +42,200. In contrast, complicated below-knee amputation cost +40,600 and added 12.5 hospitalization days. There is therefore no cost-benefit in primary amputation when compared with arterial reconstruction, and cost should not be used to deny a patient the opportunity for limb salvage.

Amputation, Surgical↗
PubMed1988

Carotid endarterectomy: what is its current status?

The plethora of recent articles regarding carotid endarterectomy has tended to confuse rather than clarify its indications, efficacy, and acceptability. The National Institutes of Health has recently funded two large multicenter controlled clinical trials, one including asymptomatic persons with carotid stenoses, and the other, patients having transient ischemic episodes or minor strokes. Eight academic professors of neurology (four), neurosurgery (two), and vascular surgery (two) with a long and abiding interest in cerebrovascular disease prepared a statement delineating acceptable levels of mortality and morbidity from this procedure. These might serve as guidelines until the large trials have been completed.

Arteriosclerosis↗