Biomedical subjects

W S Moore

Publications and source records attributed to W S Moore.

At least 73 records · Page 4Linked to original sources

PubMed1996

Cigarette smoking increases the development of initial hyperplasia after vascular injury.

PURPOSE: Our purpose was to determine whether exposure to cigarette smoke increases the development of intimal hyperplasia (IH) after vascular injury. METHODS: Sixteen adult male Sprague-Dawley rats underwent standardized balloon catheter injury of the left common carotid artery. For 4 weeks before and 4 weeks after injury, animals in the experimental group (n=8) were exposed to cigarette smoke with an automated vacuum pump device. Animals in the control group (n=8) were restrained in the smoking device for an identical amount of time and underwent arterial injury at 4 vivo, prepared as histologic cross sections, and stained for elastin. IH was measured by planimetry and is reported both as the absolute area of IH and as the ratio (IH/IEL) of the absolute area of IH to the normalized area enclosed by the internal elastic lamina (expressed as a percent). RESULTS: The absolute area of IH was 2.09 +/- 0.34 for the experimental group compared with 0.94 +/- 0.25 for the control group; mean IH/IEL was 43% +/- 7.1% for the experimental group versus 17.7% +/- 4.7% for the control group (p < 0.05, two tailed unpaired t test. CONCLUSIONS: Inhalation of cigarette smoke increases the development of intimal hyperplasia in a rat model of a balloon catheter arterial injury.

Animals↗

PubMed1996

Transfemoral endovascular repair of abdominal aortic aneurysm: results of the North American EVT phase 1 trial. EVT Investigators.

PURPOSE: This report describes the results of a phase 1 trial of endovascular repair of abdominal aortic aneurysm, conducted under FDA protocol in 13 U.S. medical centers from February 1993 to December 1994. METHODS: Forty-six patients 54 to 84 years of age underwent endovascular repair of abdominal aortic aneurysm (diameter, 3.8 to 7.1 cm). Fifteen were treated with the original device (EGS-I), and 31 with a revised over-the-wire system (EGS-II). All patients were periodically observed with contrast-enhanced computed tomographic scan, color-flow duplex scan, and plain abdominal films to evaluate the stability of prosthetic location and to detect any vascular communication with or entry of blood into the aneurysm sac or change in aneurysm size. RESULTS: Thirty-nine implants (85%) were successful; average operating time was 194 minutes. Seven attempts were unsuccessful and were converted to open repair without complication (EGS-I, 5 of 15; EGS-II, 2 of 31). Conversions were caused by iliac stenosis in four patients, subintimal deployment in one, proximal displacement in one, and short distal neck in one. No patients died within 30 days of surgery. Complications included myocardial infarction in one patient, iliofemoral arterial injury in eight, wound infection in seven, required transfusion in eight, transient unexplained fever in nine, and minor emboli with foot petechiae in two. There were no amputations, major emboli, or episodes of mesenteric ischemia. Contrast enhancement outside the graft but within the aneurysm sac was detected initially in 17 grafts (44%), of which nine (53%) resolved spontaneously. Of eight persistent leaks into the aneurysm sac, one was controlled with transluminal balloon angioplasty and one required surgical explanation because of aneurysm enlargement. Six patients continued to have contrast enhancement, but had no evidence of aneurysm enlargement from 6 to 27 months after surgery. Hospital stay averaged 3.8 days (range, 1 to 13 days). Follow-up extends to 27 months, with one non-device related death of respiratory failure at 6 months. Metallic attachment system fracture, a device-related malfunction, was identified in nine implants (23%), which led to one removal; the remaining eight functioned normally with no untoward sequelae. The program was suspended while the defect was corrected. Preparations are complete for the phase 2 portion of the trial. CONCLUSIONS: Endovascular repair of abdominal aortic aneurysm appears to be safe and efficacious. Long-term results and late consequences of attachment system fracture have yet to be determined. The long-term results of perigraft leak into the aneurysm sac are unknown but worrisome in view of adverse outcomes reported by other investigators.

Aged↗

PubMed1996

Aspirin increases tissue oedema after skeletal muscle ischaemia and reperfusion.

PURPOSE: Skeletal muscle ischaemia reperfusion syndrome affects patients following lower limb revascularisation. Aspirin has the potential to attenuate these effects. METHODS: Using an established model of hind limb tourniquet ischaemia, the effects of oral and intravenous aspirin administration were observed after 6 h of ischaemia and 18 h reperfusion. Samples were obtained and analysed for muscle viability and oedema, and lung neutrophil infiltration. RESULTS: Aspirin, when compared to placebo and controls, significantly increased muscle interstitial oedema when given orally and intravenously. It had no effect on tissue viability or lung neutrophil infiltration. CONCLUSION: Aspirin increases tissue oedema after ischaemia and reperfusion but has no effect on tissue viability. Although its mechanism of action has not been clarified, aspirin may influence the no-reflow component of ischaemia-reperfusion syndrome.

Administration, Oral↗

PubMed1996

An analysis of perioperative surgical mortality and morbidity in the asymptomatic carotid atherosclerosis study. ACAS Investigators. Asymptomatic Carotid Atherosclerosis Study.

BACKGROUND AND PURPOSE: Our aim was to determine the perioperative morbidity and mortality rates of patients in the surgical arm of the multi-institutional, prospective, randomized Asymptomatic Carotid Atherosclerosis Study (ACAS). METHODS: Of 828 patients with carotid stenosis of 60% or more randomized to the surgical arm of ACAS, 721 underwent carotid endarterectomy (CEA). To qualify for participation, surgeons were required to have performed at least 12 CEAs per year with a combined neurological morbidity and mortality rate no greater than 3% for asymptomatic patients and 5% for symptomatic patients. Clinical centers had to demonstrate arteriographic morbidity less than 1% and mortality less than 0.1% per year. Primary events were stroke and death in the period between randomization and 30 days after surgery; secondary events were transient ischemic attack and myocardial infarction occurring in the same period. RESULTS: Of the 721 patients who underwent CEA, 1 died and 10 others had strokes within 30 days (1.5%). Of the 415 who underwent arteriography after randomization but before CEA, 5 (1.2%) suffered transient ischemic attack or stroke caused by arteriography. Thus, a nearly equal risk of stroke was associated with both CEA and carotid arteriography. In addition, 6 transient ischemic attacks and 3 myocardial infarctions could be directly linked to CEA, for a total CEA event rate of 2.6%. CONCLUSIONS: Patients with asymptomatic internal carotid artery stenosis exceeding 60% reduction in diameter who are acceptable candidates for elective operation may be considered for CEA if the combined arteriographic and surgical complication rates are 3% or less.

Anesthesia↗

PubMed1995

Guidelines for carotid endarterectomy. A multidisciplinary consensus statement from the Ad Hoc Committee, American Heart Association.

BACKGROUND AND PURPOSE: Indications for carotid endarterectomy have engendered considerable debate among experts and have resulted in publication of retrospective reviews, natural history studies, audits of community practice, position papers, expert opinion statements, and finally prospective randomized trials. The American Heart Association assembled a group of experts in a multidisciplinary consensus conference to develop this statement. METHODS: A conference was held July 16-18, 1993, in Park City, Utah, that included recognized experts in neurology, neurosurgery, vascular surgery, and healthcare planning. A program of critical topics was developed, and each expert presented a talk and provided the chairman with a summary statement. From these summary statements a document was developed and edited onsite to achieve consensus before final revision. RESULTS: The first section of this document reviews the natural history, methods of patient evaluation, options for medical management, results of surgical management, data from position statements, and results to date of prospective randomized trials for symptomatic and asymptomatic patients with carotid artery disease. The second section divides 96 potential indications for carotid endarterectomy, based on surgical risk, into four categories: (1) Proven: This is the strongest indication for carotid endarterectomy; data are supported by results of prospective contemporary randomized trials. (2) Acceptable but not proven: a good indication for operation; supported by promising but not scientifically certain data. (3) Uncertain: Data are insufficient to define the risk/benefit ratio. (4) Proven inappropriate: Current data are adequate to show that the risk of surgery outweighs any benefit. CONCLUSIONS: Indications for carotid endarterectomy in symptomatic good-risk patients with a surgeon whose surgical morbidity and mortality rate is less than 6% are as follows. (1) Proven: one or more TIAs in the past 6 months and carotid stenosis > or = 70% or mild stroke within 6 months and a carotid stenosis > or = 70%; (2) acceptable but not proven: TIAs within the past 6 months and a stenosis 50% to 69%, progressive stroke and a stenosis > or = 70%, mild or moderate stroke in the past 6 months and a stenosis 50% to 69%, or carotid endarterectomy ipsilateral to TIAs and a stenosis > or = 70% combined with required coronary artery bypass grafting; (3) uncertain: TIAs with a stenosis < 50%, mild stroke and stenosis < 50%, TIAs with a stenosis < 70% combined with coronary artery bypass grafting, or symptomatic, acute carotid thrombosis; (4) proven inappropriate: moderate stroke with stenosis < 50%, not on aspirin; single TIA, < 50% stenosis, not on aspirin; high-risk patient with multiple TIAs, not on aspirin, stenosis < 50%; high-risk patient, mild or moderate stroke, stenosis < 50%, not on aspirin; global ischemic symptoms with stenosis < 50%; acute dissection, asymptomatic on heparin. Indications for carotid endarterectomy in asymptomatic good-risk patients performed by a surgeon whose surgical morbidity and mortality rate is less than 3% are as follows. (1) Proven: none. As this statement went to press, the National Institute of Neurological Disorders and Stroke issued a clinical advisory stating that the Institute has halted the Asymptomatic Carotid Atherosclerosis Study (ACAS) because of a clear benefit in favor of surgery for patients with carotid stenosis > or = 60% as measured by diameter reduction. When the ACAS report is published, this indication will be recategorized as proven. (2) acceptable but not proven: stenosis > 75% by linear diameter; (3) uncertain: stenosis > 75% in a high-risk patient/surgeon (surgical morbidity and mortality rate > 3%), combined carotid/coronary operations, or ulcerative lesions without hemodynamically significant stenosis; (4) proven inappropriate: operations with a combined stroke morbidity and mortality > 5%.

Arterial Occlusive Diseases↗

PubMed1995

The role of endovascular grafting technique in the treatment of infrarenal abdominal aortic aneurysm.

The objective of this report is to review the author's initial clinical experience with screening a population of patients with abdominal aortic aneurysm, to describe the selection criteria for endovascular repair and to report results from a single institution. The technique of transfemoral repair of abdominal aortic aneurysm uses the endovascular graft system that is currently in a Food and Drugs Administration approved protocol for investigation in the United States. Some 69 patients with abdominal aortic aneurysm were screened in order to find ten suitable candidates. Ten implantations were carried out, of which eight were successful and two required conversion to conventional open aneurysm repair without complication. There were no deaths or complications. It is concluded that tube graft repair by the transfemoral route is feasible and applicable to approximately one patient in seven. The availability of a bifurcated graft will enhance the percentage of aneurysm patients treatable by this technique. Long-term results, at this time, are unknown.

Aortic Aneurysm, Abdominal↗

PubMed1995

Preliminary experience with the Endovascular Technologies bifurcated endovascular aortic prosthesis in a calf model.

PURPOSE: The purpose of this study was to develop a bifurcated endoluminal prosthesis for transfemoral placement in the aortoiliac position with a large-animal model that would simulate human implantation. METHODS: Fifteen calves (160 to 200 kg) underwent bilateral femoral artery exposure and transfemoral placement in the aortoiliac position of a bifurcated Dacron prosthesis, inserted through a 26F sheath with an over-the-bifurcation guide wire to retrieve the contralateral limb and secured proximally and distally with self-expanding attachment systems. The preferred location was determined before implantation and compared with final implant location by caliper measurements and angiography. Events during implantation, maneuvers used to accomplish accurate deployment, and final results, as judged by angiography and clinical evaluation, were recorded. Four animals survived and were used for chronic evaluation and healing by gross and microscopic studies. RESULTS: All grafts (n = 15) were patent at the end of the procedure. All (n = 7) noncrimped grafts had minor kinks in areas of curvature, whereas eight of eight crimped grafts (device modification) had none. Torque control of the body and individual limbs was necessary to correct twists before deployment in 10 of 15 grafts, with two greater than 30-degree twists remaining, which did not appear to affect flow. One implant was entirely deployed in the aorta because of parallax error, subsequently avoided by use of a marker board placed dorsally. Three premature deployments occurred, corrected by attachment system lock modification. The mean final implant position was within 2.9 +/- 1.4 mm (aortic), 1.6 +/- 1.1 mm, and 1.5 +/- 0.8 mm (contralateral and ipsilateral iliac limbs, respectively) of the intended position. Three of four animals intended for long-term evaluation were killed prematurely because of clinically evident spinal cord ischemia. Histologic sections at 2 weeks showed early wall repair without inflammatory cells and pannus ingrowth across the anastomosis. CONCLUSION: We conclude that implantation of a bifurcated endovascular prosthesis through the bilateral femoral approach is possible, provided the intended aortic implantation site (neck) is at least 12 mm in length (mean +/- 2 SD each direction). Torque control of each portion of the device will be needed in the majority of instances, with attention to parallax effect necessary for optimal placement. This animal model is not suitable for chronic graft evaluation because of its sensitivity for spinal cord ischemia. Healing data suggest graft incorporation similar to that of a surgically placed prosthesis.

Animals↗

PubMed1995

Correlation of striatal dopamine release and peripheral hypertension after transient ischemia in gerbils.

PURPOSE: Intracranial norepinephrine release has been associated with post-carotid endarterectomy hypertension in human beings. To study this phenomenon under more controlled conditions, we studied the relationship of cerebral catecholamines and blood pressure in gerbils, whose cerebral circulation is similar to that in human beings. METHODS: Twelve anesthetized gerbils underwent iliac artery blood pressure monitoring and in vivo electrochemistry catecholamine monitoring with use of catecholamine-specific electrodes placed stereotactically into the cerebral striatum. Six gerbils underwent 10 minutes of bilateral carotid artery occlusion (ischemic), whereas six underwent carotid artery dissection without occlusion (control). RESULTS: The control group demonstrated a continuous gradual decline in blood pressure and striatal catecholamine during the 150-minute observation period. In contrast the ischemic gerbils demonstrated a sharp catecholamine rise during ischemia, a marked catecholamine drop shortly after carotid artery unclamping, and then a secondary larger catecholamine release that peaks in 60 minutes and gradually returns to baseline in 120 minutes. The blood pressure closely followed the catecholamine levels, with a sharp 20 mm Hg rise in blood pressure above baseline during carotid artery occlusion, followed by a dramatic 10 mm Hg drop below baseline after carotid artery unclamping and then a gradual rise of the blood pressure 25 mm Hg above baseline, which peaks in 80 minutes, with a gradual decline to the same blood pressure as in the control subjects 120 minutes after ischemia. CONCLUSION: We conclude that striatal catecholamine release correlates with peripheral blood pressure during transient cerebral ischemia and reperfusion. This phenomenon may explain the mechanism of post-carotid endarterectomy hypertension in human beings, and this gerbil model can be used to study its prevention and treatment.

Animals↗

PubMed1995

Laparoscopic aortofemoral bypass. Initial experience in an animal model.

OBJECTIVE: The study objective was to evaluate the feasibility of laparoscopic aortofemoral bypass in a porcine model. SUMMARY BACKGROUND DATA: Laparoscopic techniques have been applied to numerous general and thoracic surgical procedures. Their application to vascular surgery has been virtually nonexistent. Open surgery for aortoiliac occlusive disease is accompanied by significant morbidity rates, and minimally invasive procedures have the disadvantage of reduced patency rates. Laparoscopic aortofemoral replacement has the theoretical advantage of long-term patency with reduced postoperative complications. METHODS: Between January and September 1993, laparoscopic surgery was performed on 16 pigs: 6 underwent transperitoneal laparoscopic aortic dissection and vessel control alone; 7 underwent complete transperitoneal laparoscopic aortofemoral bypass; and 3 underwent a retroperitoneal approach. The aortic anastomosis was performed using a combination of sutures and titanium clips in an end-to-side fashion in five pigs, and a custom-made nonsutured graft was secured with use of an end-to-end method in five pigs. Femoral anastomoses were performed with the standard open technique. RESULTS: Technical success was achieved in all 10 animals and with no major complications. Mean blood loss was 20 ml (range, 5-50 ml), and mean operative time was 2.45 hours (range, 2-4 hrs). On aortic-clamp release, 2 of the end-to-side anastomoses required additional sutures to stop bleeding between oversized staples, and 2 of the end-to-end anastomoses required additional ties to reinforce loose ties. All 10 grafts and anastomoses were patent and free of leaks after completion of the procedure. CONCLUSIONS: Laparoscopic aortofemoral bypass is technically feasible in a porcine model. Further experimental work with new instrumentation and technical refinement will make laparoscopic surgery feasible for the treatment of vascular disease in humans.

Anastomosis, Surgical↗

PubMed1995

Guidelines for carotid endarterectomy. A multidisciplinary consensus statement from the ad hoc Committee, American Heart Association.

BACKGROUND AND PURPOSE: Indications for carotid endarterectomy have engendered considerable debate among experts and have resulted in publication of retrospective reviews, natural history studies, audits of community practice, position papers, expert opinion statements, and finally prospective randomized trials. The American Heart Association assembled a group of experts in a multidisciplinary consensus conference to develop this statement. METHODS: A conference was held July 16-18, 1993, in Park City, Utah, that included recognized experts in neurology, neurosurgery, vascular surgery, and healthcare planning. A program of critical topics was developed, and each expert presented a talk and provided the chairman with a summary statement. From these summary statements a document was developed and edited onsite to achieve consensus before final revision. RESULTS: The first section of this document reviews the natural history, methods of patient evaluation, options for medical management, results of surgical management, data from position statements, and results to date of prospective randomized trials for symptomatic and asymptomatic patients with carotid artery disease. The second section divides 96 potential indications for carotid endarterectomy, based on surgical risk, into four categories: (1) Proven: This is the strongest indication for carotid endarterectomy; data are supported by results of prospective contemporary randomized trials. (2) Acceptable but not proven: a good indication for operation; supported by promising but not scientifically certain data. (3) Uncertain: Data are insufficient to define the risk/benefit ratio. (4) Proven inappropriate: Current data are adequate to show that the risk of surgery outweighs any benefit. CONCLUSIONS: Indications for carotid endarterectomy in symptomatic good-risk patients with a surgeon whose surgical morbidity and mortality rate is less than 6% are as follows. (1) Proven: one or more TIAs in the past 6 months and carotid stenosis > or = 70% or mild stroke within 6 months and a carotid stenosis > or = 70%; (2) acceptable but not proven: TIAs within the past 6 months and a stenosis 50% to 69%, progressive stroke and a stenosis > or = 70%, mild or moderate stroke in the past 6 months and a stenosis 50% to 69%, or carotid endarterectomy ipsilateral to TIAs and a stenosis > or = 70% combined with required coronary artery bypass grafting; (3) uncertain: TIAs with a stenosis < 50%, mild stroke and stenosis < 50%, TIAs with a stenosis < 70% combined with coronary artery bypass grafting, or symptomatic, acute carotid thrombosis; (4) proven inappropriate: moderate stroke with stenosis < 50%, not on aspirin; single TIA, < 50% stenosis, not on aspirin; high-risk patient with multiple TIAs, not on aspirin, stenosis < 50%; high-risk patient, mild or moderate stroke, stenosis < 50%, not on aspirin; global ischemic symptoms with stenosis < 50%; acute dissection, asymptomatic on heparin. Indications for carotid endarterectomy in asymptomatic good-risk patients performed by a surgeon whose surgical morbidity and mortality rate is less than 3% are as follows. (1) Proven: none. (As this statement went to press, the National Institute of Neurological Disorders and Stroke issued a clinical advisory stating that the Institute has halted the Asymptomatic Carotid Atherosclerosis Study (ACAS) because of a clear benefit in favor of surgery for patients with carotid stenosis > or = 60% as measured by diameter reduction. When the ACAS report is published, this indication will be recategorized as proven. (2) acceptable but not proven: stenosis > 75% by linear diameter; (3) uncertain; stenosis > 75% in a high-risk patient/surgeon (surgical morbidity and mortality rate > 3%), combined carotid/coronary operations, or ulcerative lesions without hemodynamically significant stenosis; (4) proven inappropriate: operations with a combined stroke morbidity and mortality > 5%.

Aspirin↗

PubMed1995

Cigarette smoking accelerates carotid artery intimal hyperplasia in a dose-dependent manner.

BACKGROUND AND PURPOSE: Intimal hyperplasia is the single most important cause of early restenosis after carotid endarterectomy. Cigarette smoking is an independent risk factor associated with peripheral vascular disease and cerebrovascular accidents. We undertook a dose-response experiment to determine the effect of cigarette smoke on development of intimal hyperplasia in a rat carotid artery intimal injury model. METHODS: Seventy-two rats were divided into six equal groups and underwent standardized balloon injury to the carotid artery. Each group received 0 (controls), 1, 2, 3, 6, or 8 cigarettes per day for 4 weeks. Resultant intimal hyperplasia was expressed as a percentage of original lumen replaced by intimal hyperplasia. RESULTS: Percent intimal hyperplasia development (+/- SD) was as follows: controls (0 cigarettes per day), 17.7 +/- 13.2; 1 cigarette per day, 22.8 +/- 15.0; 2 cigarettes per day, 20.0 +/- 14.7; 3 cigarettes per day, 19.2 +/- 12.1; 6 cigarettes per day, 43.5 +/- 15.5; and 8 cigarettes per day, 36.7 +/- 9.8. Six and 8 cigarettes per day significantly increased the development of intimal hyperplasia after intimal injury (P < .01). CONCLUSIONS: High-dose cigarette smoke accelerates development of intimal hyperplasia and may pose a significant risk factor in developing carotid restenosis.

Animals↗

PubMed1995

Carotid-subclavian bypass for brachiocephalic occlusive disease. Choice of conduit and long-term follow-up.

BACKGROUND AND PURPOSE: Atherosclerotic disease of the proximal brachiocephalic circulation may produce disabling symptoms referable to cerebral or upper extremity hypoperfusion and embolization. Bypass of occlusive lesions can provide durable relief of symptoms with minimal complications. The ideal conduit for carotid-to-subclavian and subclavian-to-carotid bypass remains controversial, and it is not clear whether the outflow vessel influences patency and survival. METHODS: We performed a retrospective analysis of 60 consecutive carotid-to-subclavian and subclavian-to-carotid bypass procedures. Occlusive lesions were documented preoperatively by arteriography. Patency was determined during follow-up by ultrasound or duplex examination. Actuarial patency, symptom-free survival, and overall survival rates were calculated by the life-table method and analyzed by log-rank test. RESULTS: Arterial transposition demonstrated the highest long-term patency rate (100.0 +/- 0.0%). Polytetrafluoroethylene grafts demonstrated the highest bypass graft patency rate (95.2 +/- 4.6%), followed by Dacron grafts (83.9 +/- 10.5%) and saphenous vein grafts (64.8 +/- 16.5%). Symptom-free survival paralleled patency rates, but these differences did not achieve statistical significance. While there were no differences in patency or symptom-free survival by outflow vessel, the overall survival of patients with common carotid lesions was significantly lower than that of patients with subclavian lesions (62.7 +/- 12.8% versus 100.0 +/- 0.0%; P < .05). CONCLUSIONS: The outflow vessel does not affect long-term patency in carotid and subclavian bypass procedures; however, patients with common carotid disease demonstrate significantly poorer long-term survival. Transposition results in superior long-term patency, with a trend toward lower results for synthetic grafts and relatively poor results for autogenous vein grafts.

Adult↗

PubMed1995

Display of cross sectional anatomy by nuclear magnetic resonance imaging. 1978.

High definition cross-sectional images produced by a new nuclear magnetic resonance (NMR) technique are shown. The images are a series of thin section scans in the coronal plane of the head of a rabbit. The NMR images are derived from the distribution of the density of mobile hydrogen atoms. Various tissue types can be distinguished and a clear registration of gross anatomy is demonstrated. No known hazards are associated with the technique.

Animals↗

PubMed1995

Pharmacologic suppression of intimal hyperplasia: a dose-response suppression by enalapril.

Intimal hyperplasia is an exaggerated proliferative response to arterial intimal injury. A successful means of limiting this hyperplastic response would significantly improve patency rates of vascular reconstruction. Angiotensin-converting enzyme (ACE) inhibitors decrease the proliferation and synthetic function of vascular smooth muscle cells in vitro, which have been implicated in the production of intimal hyperplasia. We performed a dose-response study of enalapril to assess the level at which maximal suppression of intimal hyperplasia occurs. Seventy male Sprague-Dawley rats weighing 250-300 grams underwent standardized carotid artery balloon catheter endothelial denudation to induce intimal hyperplasia. Six groups of ten animals each were treated with daily intramuscular injections of one of the following doses of enalapril (mg/kg): 0.025, 0.050, 0.075, 0.100, 0.125, and 0.150. A control group (n = 10) was treated with saline. Injections were started two days before injury and continued for 4 weeks, at which time the injured arteries were pressure-fixed in vivo and harvested. EVG-stained histologic cross-sections were measured by planimetry to determine the amount of intimal hyperplasia, which was calculated as the percentage of the arterial lumen replaced by the lesion. Enalapril suppresses the development of intimal hyperplasia in a dose-responsive manner in this model. No further suppression is achieved above a dose of 0.125 mg/kg.

Animals↗

PubMed1995

The American Heart Association Consensus Statement on guidelines for carotid endarterectomy.

The process by which a multidisciplinary, expert panel arrived at a Consensus Statement concerning indications for carotid endarterectomy was reviewed. It is important to point out that this represents an interpretation of currently available data by the individual members of the Committee as it pertains to 96 specific potential indications for carotid endarterectomy. Clearly, as more data become available, it is likely that there will be changes in the opinion of the Committee members. Therefore, this represents a current status that will require a periodic update.

American Heart Association↗

PubMed1994

Carotid endarterectomy with primary closure does not adversely affect the rate of recurrent stenosis.

OBJECTIVES: To review our results with carotid endarterectomy using primary closure and to study the incidence of true recurrence in this group of patients. A secondary objective was to review the effect of risk factors on recurrence of stenosis following carotid endarterectomy. DESIGN: Cohort study. SETTING: University hospital. PATIENTS: Over 3 years, 232 patients underwent 268 endarterectomies. INDICATIONS: Transient ischemic attacks developed in 119 patients, asymptomatic stenosis in 108 patients, and stroke in 41 patients. One hundred fifty-seven patients (184 operations) qualified for late analysis by completing all aspects of follow-up. OUTCOME MEASURES: Serial duplex scans recorded stenosis (> 50% diameter reduction). Clinical evaluation identified transient ischemic attacks and stroke. RESULTS: Overall, 12 recurrent stenoses developed in the 184 patients available for study during a follow-up of 24 months (6.5% incidence of late stenosis). Of these 12 patients, only eight had either a normal completion angiogram or a normal carotid duplex scan within 3 months of surgery, thus qualifying for analysis as having developed true recurrent stenosis. True recurrent stenosis occurred in eight (4.3%) of 184 patients. Risk factor analysis did not reveal a statistically significant impact on recurrent stenosis, but several trends were identified. Gender and consumption of tobacco may predispose toward the development of recurrent stenosis. CONCLUSION: Recurrent stenosis is sufficiently uncommon following primary closure to justify continued use of this technique. Patch angioplasty may be considered in women and smokers.

Angiography↗

PubMed1994

The effect of hypofibrinogenemia and fibrinolysis on skeletal muscle function after ischemia and reperfusion.

Isometric contraction to direct supramaximal tetanic stimulation of the anterior tibialis (AT) muscle was measured in 50 New Zealand White rabbits after ischemia and reperfusion. Ischemia was produced unilaterally by collateral ligation and temporary inflow control until AT muscle function decreased to < 5% of contralateral (control) AT muscle and the ischemic interval was recorded. Reperfusion was carried out in one of the following ways: group I (n = 20), release of vascular clamps (blood reperfusion [BR]); group II (n = 10), release of vascular clamps and simultaneous intraarterial administration of 50,000 units of urokinase (urokinase reperfusion [UR]); group III (n = 10), release of vascular clamps and simultaneous administration of 50,000 units of urokinase and 28 mg (5 units) of purified rabbit plasminogen (urokinase plasminogen reperfusion [UPR]); and group IV (n = 10), animals defibrinated to < 50 mg/dl with ancrod prior to ischemia and received BR (ancrod blood reperfusion [ABR]). During reperfusion, function was recorded every 60 min for 2 hr. Recovery of experimental muscle function is expressed as the percentage of contralateral control limb function. The mean ischemic interval (mean +/- SEM), to achieve < 5% of contralateral control limb function, was 206.7 +/- 9.9, 209.5 +/- 16.6, 221.7 +/- 12.5, and 272.0 +/- 14.2 min for animals in groups I-IV, respectively. The mean experimental muscle function (mean +/- SEM) following the ischemic interval was 3.2 +/- 0.8, 4.5 +/- 1.4, 4.4 +/- 1.2, and 3.3 +/- 1.0 for groups I-IV, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Afibrinogenemia↗

PubMed1994

Isolated limb thrombolysis with extracorporeal pump and urokinase.

In order to determine the effect of altering the method of delivery of lytic therapy, both hind limbs of 55 adult mongrel dogs were embolized to occlusion and divided into six different treatment groups. Each right limb received 100,000 units of urokinase (UK) intraarterially by one of six different treatment protocols: Group I (n = 10), 5-min infusion with control of arterial inflow (IC); Group II (n = 10), 5-min infusion without IC; Group III (n = 10), 30-min infusion with IC; Group IV (n = 10), 30-min infusion without IC (simulates percutaneous infusion); Group V (n = 10), isolated limb perfusion (ILP) with femoral arterial and venous cannulation and proximal tourniquet control using an extracorporeal circulating pump at a controlled rate and constant temperature (37 degrees C) for 30 min; Group VI (n = 5), underwent ILP without urokinase. A morphometric score was used to quantitate angiographic changes. Films were compared before and after treatment and the net difference for each animal was recorded. [table: see text] We conclude that maintenance of blood flow during urokinase infusion enhances its effectiveness and, contrary to previous recommendations, during intraoperative delivery, inflow should be maintained. Isolated limb perfusion alone was as effective as a 30-min infusion of urokinase without inflow control. Isolated limb perfusion plus UK was by far the most effective method of administering lytic therapy. These experiments suggest that the mechanical action of flowing blood enhances clot dissolution and significantly increases the effectiveness of pharmacologic lysis. Isolated limb fibrinolytic perfusion may have clinical potential in the surgical treatment of limb ischemia.

Angiography↗