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Biomedical subjects

W H Edwards

Publications and source records attributed to W H Edwards.

At least 37 records · Page 2Linked to original sources
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

Effects of vesicocolic anastomosis on the proliferation of colonic mucosa in a rat model.

The effects of diverting the urinary stream into a defunctioned segment of the distal colon has been studied in a rat model. Distal rat colon was defunctioned using the Hartmann's procedure and a vesicocolic anastomosis was performed 14 days later. The distal colon was harvested after 10 days following the administration of a vinblastine mitotic block either 1 or 3 h before death. Both the mean crypt cell proliferation and the crypt length were increased significantly in the colonic mucosa exposed to urine when compared with the control defunctioned colon or to the functional unexposed proximal colon. An active fraction was obtained from human urine by elution from a diethylaminoethyl sepharose column using 1 mol/L NaCl. This fraction was administered intraluminally to defunctioned rat colons using Alzet minosmotic pumps. In these animals the crypt cell production rate was significantly increased compared with the control animals. Although the crypt length did not increase significantly in these animals the atrophy normally seen in defunctioned colonic mucosa did not occur. The identity of the active molecule in this urine fraction is still being determined.

Analysis of Variance↗
PubMed1995

An unsuspected cause for recurrent angina: subclavian artery stenosis.

The advantages of internal mammary artery (IMA) grafts over saphenous vein grafts (SVG) for coronary artery bypass grafting have been extensively recorded in the literature. Operative results and postoperative mortality in patients with IMA versus SVG are comparable. The relative risks of thrombosis, however, of an SVG are four to five times greater than an IMA graft, and the probability of recurrent angina or need for reoperation is significantly less in IMA grafted patients. Coltharp et al. also showed that the risks of reoperation for recurrent angina were decreased by a previously constructed IMA graft.

Adult↗
PubMed1994

Case management in cerebral revascularization.

PURPOSE: We examined the clinical and financial outcomes of case management coupled with the initiation of selective use of the intensive care unit (ICU) in all cerebral revascularization procedures. METHODS: Three hundred eighty-four procedures in 331 patients were retrospectively reviewed. Morbidity and mortality rates, hospital length of stay, cost, and ICU or hospital readmissions were examined. Hypertension was examined as an independent variable for its effect on patient outcome. RESULTS: Cerebral revascularization, including carotid endarterectomy, vertebral-carotid artery transposition, and subclavian-carotid artery transposition, yielded a 0.78% stroke rate and 0.26% perioperative death rate in this series. ICU admission was necessary in nine patients (2.3%) for cardiac or respiratory instability. Three patients (0.78%) required transfer to the ICU for management of hypertension or hypotension. The mean hospital length of stay after institution of case management was reduced by 2.1 days, and the mean cost was decreased by $1987, a savings of 28.9% of total hospital cost. CONCLUSION: The dual approach of case management and selective use of the ICU promotes quality patient care, conserves financial resources without adversely affecting morbidity or mortality rates, enhances physician/nurse collaboration, and improves patient satisfaction.

Aged↗
PubMed1994

Cryopreserved saphenous vein allografts for below-knee lower extremity revascularization.

OBJECTIVE: Cryopreserved saphenous vein allografts have been offered as an alternative conduit for bypass in ischemic limbs. The authors examined the efficacy of this conduit for arterial bypass to the distal popliteal and tibial arteries in patients in whom autogenous vein was not available. SUMMARY BACKGROUND DATA: Previous experience with arterial and venous allografts has been unsatisfactory because of aneurysmal degeneration and poor patency. Endothelial loss and host rejection have been suggested as mechanisms of graft failure. Cryopreservation by modern techniques with rate controlled freezing, dimethyl sulfoxide (DMSO), and other cryopreservants, has addressed these issues and rekindled interest in vein allografts. METHODS: Over a period of more than 5 years, 115 cryopreserved vein allografts were implanted in 87 limbs to the distal popliteal (14) or tibial (101) arteries. The indication for surgery was rest pain in 56 procedures (49%), gangrene in 36 (31%), claudication in 21 (18%), and replacement of aneurysmal allografts in 2. Follow-up was 1 to 61 months (mean 25 months). RESULTS: There was no significant difference in patency related to site of proximal or distal anastomosis, patency of runoff vessels, use of anticoagulation, age, sex, diabetes, hypertension, smoking, indication, source of graft, or use of multiple segments. Revision was required in six grafts for aneurysmal dilatation. Histologic examination of explanted sections of allografts showed no immune response, and immunosuppressive drugs were not used. CONCLUSIONS: Although limb salvage has been satisfactory, long-term patency rates for cryopreserved vein allografts are poor when compared with autogenous vein. The cost of cryopreserved allografts far exceeds that of prosthetic grafts, for which comparable and superior results have been reported. Use of cryopreserved vein allografts should be reserved for situations in which adequate lengths of autogenous vein do not exist and the risk of infection of prosthetic grafts is high.

Adult↗
PubMed1994

Subclavian revascularization. A quarter century experience.

OBJECTIVE: Twenty-five years of experience with subclavian revascularizations were reviewed to determine the long-term patency rates of different extrathoracic approaches. SUMMARY BACKGROUND DATA: Although it is generally agreed that proximal subclavian stenosis should be treated by an extrathoracic route whenever possible, the optimum procedure is debated. Alternatives include subclavian carotid bypass, subclavian-to-subclavian or axillo-axillary bypasses, and the authors' preferred technique of subclavian carotid transposition (SCT). METHODS: Records were researched for the past 25 years in a single specialty surgical clinic for extrathoracic subclavian revascularizations. One hundred ninety such procedures were identified, and hospital charts and office medical records were reviewed for procedure, preoperative symptoms, blood pressure differentials, and postoperative complications. Patency was determined by physical examination, differential blood pressures, Doppler spectral analysis, duplex examinations, and arteriography. RESULTS: Bypass procedures were used infrequently, and although the results are reported, they are excluded from any analysis. Subclavian carotid transposition was used in 178 procedures. All anastomoses were found to be patient at follow-up, except for one, which failed at 26 months. Mean follow-up was 46 months, with five patients lost to follow-up. Overall mortality rate was 2.2%, with the mortality falling to 1.1% if only subclavian carotid transposition patients are included. CONCLUSIONS: Subclavian carotid transposition should be the treatment of choice for routine subclavian carotid occlusive disease because of its exceptional long-term patency and low morbidity.

Adult↗
PubMed1994

Recurrent aortic occlusion.

In a review of 134 aortic occlusions in 123 patients, there were 10 patients that suffered recurrent aortic occlusions (RAO). These patients developed RAO after revascularization for primary aortic occlusion and presented with signs and symptoms of acute lower extremity ischemia. The recurrent occlusions occurred in one native aorta and in 10 aortobifemoral grafts. The etiology of the primary aortic occlusion included chronic aortic occlusion in eight patients and acute aortic occlusion and aortic graft occlusion in one patient each. Original primary operations performed included aortoiliac thromboendarterectomy with Dacron patch aortoplasty (1 patient), AF bypass (8 patients), and aortofemoral graft thrombectomy (1 patient). All of the grafts had end-to-end proximal anastomoses, the diameter of which ranged from 12 to 16 mm. Secondary operations performed for RAO included six axillofemoral bypasses, four redo aortobifemoral bypasses, and one graft thrombectomy. All patients were managed with immediate anticoagulation, expeditious arteriography, and revascularization. There were no perioperative deaths, and no limbs were lost. No patient was lost to follow-up (mean 10 years). Extra-anatomic bypass has proved durable. Redo aortobifemoral bypass is useful in selected patients with surgically correctable lesions.

Acute Disease↗
PubMed1993

Neonatal pain: a comprehensive survey of attitudes and practices.

We surveyed 352 physicians board certified in neonatal-perinatal medicine on their attitudes and practices in the area of pain and pain management in neonates and infants. In contrast to earlier surveys of this type, almost all respondents indicated that even the youngest and most premature infants are able to perceive pain, and most reported that they always advocated anesthesia during the intraoperative period. The use of analgesic agents in the postoperative period, however, was more variable. Respondents who indicated that neonates perceived less pain than adults reported seeing fewer signs of pain and using less analgesia in the postoperative period. They were also more likely to believe that analgesics are too dangerous to use in neonates and that physiologic factors such as incomplete myelination of the pain pathways and neural/physical immaturity (factors now known not to play a role) contribute to diminished pain sensitivity. Conversely, respondents who indicated that neonates do not perceive less pain than adults, the majority of respondents, reported seeing more signs of pain and using more medication in the postoperative period. These physicians also believed that the physiologic stress associated with pain can be more dangerous than the analgesics. We conclude that attitudes and reported practices have changed in the area of neonatal pain and pain management. Furthermore, our data indicate that these attitudes significantly predict reported postoperative medicating practices.

Attitude of Health Personnel↗
PubMed1993

Surgical treatment of common carotid artery occlusion.

Eight patients with common carotid artery (CCA) occlusion underwent bypass with saphenous vein to either the carotid bifurcation (five), the internal carotid artery (two), or the external carotid artery (one). Indications included ipsilateral transient ischemic attack (two), recent nondisabling hemispheric stroke (two), and transient nonhemispheric cerebral symptoms (two). Two asymptomatic patients with CCA occlusion and contralateral internal carotid stenosis underwent prophylactic revascularization prior to planned aortic surgery. There were no perioperative strokes, occlusions, or deaths. Late ipsilateral stroke occurred in two patients, and one patient had a single transient ischemic attack after 2 years. The four patients with preoperative transient cerebral ischemia experienced relief of their symptoms. Duplex ultrasound is an accurate screening modality for distal patency. Collateral filling of the internal or external carotid artery can usually be demonstrated after aortic arch or retrograde brachial contrast injection. End-to-end distal anastomosis after endarterectomy eliminates the original occlusive plaque as a potential source of emboli. The subclavian artery is preferred for inflow on the left. The CCA origin is easily accessible for inflow on the right. Bypass of the occluded CCA is safe and may be effective in relieving transient cerebral ischemic symptoms, although long-term ipsilateral neurologic sequelae may still occur.

Aged↗
PubMed1993

Suprarenal aortic occlusion.

PURPOSE: This report was designed to elucidate the clinical manifestations of suprarenal aortic occlusion (SRAO) and determine the efficacy of surgical treatment. METHODS: A retrospective review of 135 patients with aortic occlusion was undertaken from which the 16 patients (12%) with SRAO were found. RESULTS: Analysis yielded two subsets of patients based on the time-frame over which SRAO developed. Group I (n = 13) had chronic aortic occlusion with proximal propagation of thrombus to involve the suprarenal aorta. They had uncontrolled hypertension and claudication. Surgical treatment included 16 renal reconstructions (nine patients), two nephrectomies, 10 aortobifemoral bypasses, and three extra-anatomic procedures. The operative mortality rate was 23%. In contrast, group II (n = 3) had acute SRAO, manifest by profound lower extremity ischemia and acute renal failure after cardiac dysrhythmias. Two patients were moribund and died shortly after extraanatomic "salvage" procedures. One patient survived aortobifemoral and bilateral renal artery bypass. CONCLUSION: Chronic SRAO should be suspected in patients with absent femoral pulses and refractory hypertension. Aortic and renal reconstruction offers long-term improvement in hypertension control and relief of claudication. Acute SRAO is a multisystem disorder that is ineffectively managed with extraanatomic "salvage" procedures.

Acute Disease↗
PubMed1993

Cefamandole versus cefazolin in vascular surgical wound infection prophylaxis: cost-effectiveness and risk factors.

PURPOSE: Recent studies of perioperative antimicrobial prophylaxis have indicated an improved efficacy of beta-lactamase-stable cephalosporins compared with cefazolin, the most commonly used prophylactic agent. Previous studies in our institution have revealed a superiority of cefamandole to cefazolin in patients undergoing heart surgery, although there was no difference between cefazolin and cefuroxime in patients undergoing peripheral vascular surgery. This study was therefore designed to compare cefamandole with cefazolin in wound infection prophylaxis in clean vascular surgery. METHODS: The study was conducted from August 1990 through May 1992 and consisted of 893 patients with aortic or infrainguinal arterial procedures randomized to receive either cefamandole or cefazolin. RESULTS: The difference in infection rates associated with cefamandole versus cefazolin prophylaxis (3.2% vs 1.9%, respectively) was not significant (p = 0.42). A cost savings of approximately $95,000 per year at our institution favors the continued use of cefazolin over cefamandole. Risk factor analysis was carried out for preoperative and postoperative events that might have predisposed to infection. Only preoperative use of aspirin and the postoperative finding of a lymphocele correlated with a higher infection rate. CONCLUSIONS: Cefazolin continues to be the most cost-effective antibiotic for prophylaxis in clean vascular surgical procedures.

Adult↗
PubMed1993

Dysphagia lusoria: aberrant right subclavian artery with a Kommerell's diverticulum.

A retroesophageal right subclavian artery, the most common congenital aortic arch abnormality, is an unusual cause of dysphagia in adults. The embryologic abnormality of the aortic arch is involution of the fourth vascular arch, along with the right dorsal aorta, leaving the seventh intersegmental artery attached to the descending aorta. This persistent intersegmental artery assumes a retroesophageal position as it proceeds out of the thorax into the arm. Since compression of the esophagus by this right subclavian artery may produce dysphagia, the term "dysphagia lusoria" ("dysphagia by freak of nature"), has been used to describe the symptom complex. The presence of an aneurysm of the artery or Kommerell's diverticulum at its aortic origin is more likely to produce symptoms from esophageal compression. This case presents a middle aged adult with an associated Kommerell's diverticulum and dysphagia. Surgical correction was used to relieve his symptoms and to correct the diverticulum of the proximal right subclavian artery. The embryologic changes that occur are discussed in detail.

Aorta, Thoracic↗
PubMed1992

Cefuroxime versus cefazolin as prophylaxis in vascular surgery.

Although cefazolin prophylaxis has proven efficacy in vascular surgery, Staphylococcus aureus wound infections are still an important postoperative complication. In cardiac surgery, cefazolin's susceptibility to hydrolysis by staphylococcal beta-lactamase has been proposed to account for some prophylaxis failures. To determine whether the incidence of vascular wound infections can be reduced by administering a more beta-lactamase-stable cephalosporin, we undertook a prospective, randomized trial of cefuroxime versus cefazolin. Cefuroxime was administered as a 1.5 gm dose before operation and 750 mg every 3 hours during operation. Cefazolin was given as 1 gm before operation and 500 mg every 4 hours during operation. Both agents were continued every 6 hours after operation for 24 hours. Deep wound infections developed in seven of 272 (2.6%) cefuroxime and three of 287 (1.0%) cefazolin recipients (p = 0.2). Staphylococcus aureus wound infections occurred in five cefuroxime versus two cefazolin recipients. In vitro evaluation of six of the study isolates plus an additional eight S. aureus strains from vascular wound infections showed greater susceptibility of the strains to cefazolin than cefuroxime (median minimal inhibitory concentrations of 0.5 and 2.0 micrograms/ml, respectively, p less than 0.05). Furthermore, despite its more frequent intraoperative redosing, cefuroxime exhibited lower trough serum concentrations than cefazolin. Among cefuroxime recipients, infection-associated procedures were significantly longer than infection-free procedures (p less than 0.05), suggesting that low tissue antibiotic concentrations may have contributed to the pathogenesis of these infections. In contrast, the length of the procedure was not a risk factor for infection among cefazolin recipients.(ABSTRACT TRUNCATED AT 250 WORDS)

Cefazolin↗
PubMed1992

Juxtarenal aortic occlusion.

The authors' experience with 113 aortic occlusions in 103 patients during a 26-year period (1965 to 1991) is reviewed. The authors found three distinct patterns of presentation: group I (n = 26) presented with acute aortic occlusion, group II (n = 66) presented with chronic aortic occlusion, and group III (n = 21) presented with complete occlusion of an aortic graft. Perioperative mortality rates were 31%, 9%, and 4.7% for each respective group and achieved statistical significance when comparing group I with group II (p = 0.009) and group I with group III (p = 0.015). Group I presented with profound metabolic insults due to acute ischemia and fared poorly. Group II presented with chronic claudication and did well long-term. Group III presented with acute ischemia but did well because of established collateral circulation. The treatment and expected outcome of aortic occlusion depends on the cause.

Actuarial Analysis↗
PubMed1992

Surviving gastrointestinal infarction due to polyarteritis nodosa: a rare event.

Poly arteritis nodosa (PAN) is a systemic vasculitis with a male: female ratio of 2:1 and a peak incidence in the fifth decade. Small to medium-sized arteries are involved by focal transmural inflammatory necrosis. Aneurysms with inflammatory destruction of the media also occur. The most frequently involved organs are the kidney, heart, lung, liver, and gastrointestinal tract. There are few reported cases of ischemic necrosis of the intestine and even fewer survivors. A 22-year-old woman was transferred to St. Thomas Hospital (Nashville, TN) after resection of 80 per cent of the small bowel for ischemic necrosis. She had a history of juvenile onset diabetes mellitus, recurrent abdominal pain, and splinter hemorrhages. Emergency aortogram and selective mesenteric arteriogram were performed. The celiac artery was not visualized and small aneurysms were present in the mesenteric and renal arteries. The patient was successfully resuscitated from a cardiac arrest in x ray from a cardiac tamponade. Laparotomy was performed to determine the viability of the bowel. The celiac, hepatic, and splenic arteries were found to be chronically occluded. Pathology of these arteries revealed a nonspecific arteritis. At a third operation, several more inches of small bowel were removed. Characteristic changes of PAN were present on all small bowel specimens. She was treated with high-dose cyclophosphamide and steroids for 6 months and has continued on low-dose cyclophosphamide. She is now 36 months from her original operation and is doing well on oral nutrition. Intestinal hemorrhage from aneurysm rupture or gangrene with perforation are gastrointestinal complications of PAN that the surgeon may be called upon to treat.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The evolving surgical management of recurrent carotid stenosis.

The traditional approach to recurrent carotid stenosis has been repeat endarterectomy or patch angioplasty. Concern with the durability of repeat carotid endarterectomy has resulted in our use of carotid resection with autogenous graft interposition. This study was designed to determine the outcome and efficacy of carotid resection compared with repeat carotid endarterectomy in the management of recurrent carotid stenosis. From 1974 to 1991, 162 operations (repeat carotid endarterectomy 105, carotid resection 57) were performed for recurrent carotid stenosis. Indication for operation was hemispheric symptoms in 63% of patients, nonlateralizing symptoms in 25%, asymptomatic stenosis in 7%, and previous stroke in 5%. Ninety-one percent of patients had stenosis greater than 90% on arteriography. The perioperative stroke rate for carotid resection was 3.5%, with a subsequent rate of 0.0064 strokes per year. For repeat carotid endarterectomy, the perioperative stroke rate was 1.9% with a subsequent rate of 0.011 strokes per year. Graft patency after carotid resection was 93% (mean follow-up, 35 months). Four patients treated with carotid resection had graft thrombosis, and two of the four remained asymptomatic. After repeat carotid endarterectomy, one patient had carotid thrombosis, and recurrent stenosis greater than 50% developed in 23 patients (mean follow-up, 64 months). Twenty patients treated with repeat carotid endarterectomy underwent an additional operation for further symptomatic recurrent carotid stenosis. We conclude carotid resection is a safe and effective alternative to repeat carotid endarterectomy for patients undergoing operation for recurrent carotid stenosis.

Aged↗