Biomedical subjects

E D Endean

Publications and source records attributed to E D Endean.

At least 19 recordsLinked to original sources

PubMed1998

Process improvements reduce utilization of resources for aortic aneurysm repair.

In conjunction with the VA reorganization to promote greater efficiency of health care provision, ambulatory surgery (AS) programs have been created. These programs institute outpatient preoperative assessment and operative management. This study examines the impact of these process changes on resources utilized by patients requiring repair of abdominal aortic aneurysms (AAAs). The medical records of 15 consecutively treated patients undergoing elective, infrarenal AAA repair before (1992-1993) and after (1995-1996) AS implementation were reviewed. Resource utilization was assessed by evaluating preoperative tests performed (inpatient or outpatient), ICU days, and inpatient length of stay (LOS). Postoperative morbidity and mortality were noted. Patient age, AAA size, and prevalence of diabetes mellitus, hypertension, cardiac disease, COPD, and tobacco use were similar between the two groups. Abdominal ultrasound, CT scanning, and angiography were significantly more frequently performed on an outpatient basis after implementation of the AS program. The median preoperative LOS was reduced in the AS group (1 vs 6 days, P = 0.001, Student t test), resulting in a lower inpatient LOS (11 vs 16, P < 0.01, Student t test). All patients survived and the incidence of complications was similar between the groups. Hospital resource utilization was significantly decreased, largely by shifting preoperative assessment to the outpatient setting. This study illustrates that benefits of an ambulatory surgery program can be extended beyond facilitating outpatient operations and should result in decreased length of hospitalization for other major surgical procedures, such as abdominal aortic aneurysm repair.

Aged↗

PubMed1998

Nontraumatic lower-extremity acute arterial ischemia.

BACKGROUND: The outcome of arterial bypass reconstruction in the setting of acute arterial ischemia has not been well defined. METHODS: This retrospective review consists of 71 consecutive patients (54 with native arterial thrombosis, 17 with graft thrombosis) who underwent an urgent/emergent arterial bypass reconstruction for acute arterial ischemia with threatened limb viability. RESULTS: The 30-day mortality and major amputation rates were 9.9% and 7.1%, respectively. Death, limb loss, or both, were associated with a paralytic limb (P = 0.001) and congestive heart failure (P = 0.03). Overall, 45 of 71 (63%) patients were discharged with limb salvage and ambulatory function. Cumulative graft patency was 77% and 65% at 1 and 2 years, respectively, and closely approximated the 1- and 2-year limb-salvage rates of 76% and 63%, respectively. CONCLUSIONS: Arterial bypass reconstructions appear warranted in acute arterial ischemia, in that a majority of patients retain a functional viable limb. Late graft thrombotic complications limit long-term benefit.

Acute Disease↗

PubMed1998

Popliteal artery thrombosis associated with trampoline injuries and anterior knee dislocations in children.

Recent reports have emphasized the benign nature of trampoline-associated injuries. However, this study describes the limb-threatening problem of popliteal artery thrombosis occurring in association with anterior knee dislocation and trampoline injuries. Three children (ages 11, 13, and 17) were referred to the emergency room within the past 12 months with anterior dislocations of the knee, which occurred while jumping on trampolines. All patients had reduction of their dislocations at outside facilities and were referred within 6 to 12 hours after their injuries, with pulse, motor, and sensory deficits. All patients were taken directly to the operating room, where arteriography confirmed thrombosis of the popliteal artery below the knee. One patient had transection of the artery, whereas two patients had stretch injuries with intimal separation. Each patient required interposition grafting with reversed saphenous vein and underwent concomitant four-compartment fasciotomy. All patients had persistent sensory and motor deficits postoperatively, which were presumed to be a combination of ischemic injury and neuropraxia. All patients have functioning grafts with an average follow-up of 1 year (range, 9-15 months). One patient required a second interposition graft to treat an area of intimal hyperplasia, which developed at the proximal anastomosis, at 6 months postoperatively. Eighty per cent of trampoline injuries are associated with minor injuries with minimal long-term complications. However, dislocations of the knee may be associated with significant arterial injury and amputation rates of up to 30 per cent in many blunt trauma series. Based on our experience, physicians should recognize the possibility of significant arterial injuries occurring in children with anterior knee dislocations while jumping on trampolines.

Adolescent↗

PubMed1997

Intra-arterial urokinase versus surgery for acute peripheral arterial occlusion.

The outcomes of intra-arterial urokinase versus surgery for acute peripheral arterial occlusion (PAO) were compared. Patients at a university hospital who had received intraarterial urokinase for PAO were identified by computer and pair-matched on the basis of comorbidities, age, sex, and site of occlusion to computer-selected patients who had undergone surgery. Only patients with category I or II ischemia were considered. The study period for the urokinase group was February 1995 through January 1996, and the period for the surgery group was June 1993 through January 1996. Twenty-eight patients in each group met the selection criteria. Patients who had received urokinase had a significantly shorter median length of stay (8.5 days) than patients in the surgery group (13 days) and significantly fewer infectious complications (2 versus 10). No differences in amputation rates, total hospital costs, or mortality rates were detected. Patients who received intra-arterial urokinase for PAO had a shorter length of stay in the hospital and fewer infectious complications than those who underwent surgery.

Adult↗

PubMed1995

An angioscopic method for intraluminal aortic evaluation and stent placement.

PURPOSE: The purpose of this study was to develop an angioscopic technique to visualize the endoluminal surface of the aorta and to guide vascular stent placement. METHODS: A fiberoptic angioscope, fitted with a balloon at its tip, was passed via a carotid arteriotomy into the abdominal aorta of seven anesthetized pigs. Saline solution inflation of the balloon allowed for blood displacement and clear visualization of the endoluminal anatomy. After the left renal artery orifice had been identified with angioscopy, a catheter was inserted via a left femoral sheath to cannulate the orifice under direct visualization. The position of the catheter was verified angiographically. A vascular stent was loaded onto an angioplasty balloon, inserted through a right femoral arteriotomy, positioned by use of angioscopic visualization, and deployed immediately below the left renal artery orifice. RESULTS: The aortic trifurcation and the lumbar and renal artery orifices were clearly visualized in every animal. Vascular stents were placed in seven animals within an average of 3.14 +/- 1.14 mm (mean +/- SEM, range 0 to 8 mm) below the inferior rim of the left renal artery orifice. No stents were positioned above a renal artery orifice or obstructed blood flow. CONCLUSIONS: This angioscopic technique permitted detailed evaluation of aortic endoluminal anatomy and precise implantation of vascular stents. Direct endovascular visualization may facilitate other endovascular procedures, including endovascular grafting.

Angioscopy↗

PubMed1995

Carotid artery occlusion after dog bite.

The etiology of most penetrating neck injuries is caused by missiles or stabbings. Irrespective of the cause of injury, management strategies require that life-threatening injuries to underlying deep neck structures such as esophagus, trachea, or carotid artery be promptly identified. A case is reported in which occlusion of the common carotid artery resulted from a dog bite to the neck. The patient presented to the emergency department with four neck lacerations but lacked focal neurologic symptoms suggestive of such an underlying deep neck injury. The carotid injury was identified by preoperative angiography and was repaired with a reversed saphenous vein interposition graft. The patient had full recovery without neurologic sequela. While injuries to deep neck structures as a result of animal bites are rare, these patients should be evaluated according to accepted protocols to exclude or identify such life-threatening injuries.

Adult↗

PubMed1994

Characterization of polyamine transport in rat aortic smooth muscle cells.

Increased arterial wall polyamine content has been linked to intimal hyperplasia (IH) formation. Intracellular polyamine content may be regulated by a polyamine transmembrane transport mechanism, but the existence of such a system has not been demonstrated in systemic arterial smooth muscle cells. This study characterizes polyamine transport as found in rat aortic smooth muscle cells. Smooth muscle cells were isolated and cultured from Sprague-Dawley rat aortas. Polyamine transport was determined by adding [14C]-polyamines to the medium, calculating transport kinetic parameters, Vmax and Km. Competition studies with unlabeled polyamines and uptake in the presence of paraquat, a polyamine transport inhibitor, were done to test the specificity of the uptake system. We identified polyamine transporters in aortic smooth muscle cells which were temperature, concentration, and time dependent. Kinetic studies revealed that spermidine and spermine had greater affinity for the transporter(s) than putrescine (Km = 0.3, 0.3, and 3.7 microM respectively; P = 0.0001) while maximum uptake velocity was similar for all polyamines (26.6-31.0 pmole/mg protein/min). Inhibition of de novo polyamine synthesis upregulated polyamine transport 2.8-3.8 times (P = 0.0001) while transporter affinity (as reflected by Km) remained unchanged. Competition studies and paraquat treatment indicated the presence of two polyamine transporters: one shared by all polyamines, the other specific for spermine and spermidine. These data indicate that transmembrane polyamine transport occurs in arterial smooth muscle cells. Upregulation of this system may represent one control mechanism for IH development.

Animals↗

PubMed1994

Morphology predicts rapid growth of small abdominal aortic aneurysms.

This study evaluated CT scans of small abdominal aortic aneurysms (AAAs) (< 5 cm) to assess anatomic features associated with rapid expansion. Serial CT scans obtained at least 10 months apart (mean 15 months) from patients with small AAAs were reviewed. Each cross-sectional image of the AAAs was analyzed using a computer-assisted design program. The circumference of the AAA in each CT image was divided into eight equal arcs, from which the apparent radius of curvature (Rc) for each segment was calculated. Flattening of the wall curvature results in an increased segmental Rc. The CT scans of nine patients with expanding AAAs (expansion > or = 0.5 cm/yr) were compared to those of 10 patients with stable AAAs (expansion < or = 0.2 cm/yr). To adjust for differences in AAA size, the Rc for each segment was normalized by dividing each individual Rc by the average of the eight Rcs (RcAvg) calculated for that cross-sectional CT image. Analysis of variance showed that the left posterolateral segments in expanding AAAs had larger Rc/RcAvg ratios than those segments in stable AAAs (1.14 +/- 0.19 vs. 0.80 +/- 0.09, p < 0.02). Laplace's law indicates that the left posterolateral segment in AAAs that grow more rapidly is subjected to greater wall tension. Flattening in the curvature of the left posterolateral wall segment was significantly associated with an increased rate of expansion in small AAAs. This finding, readily derived from standard CT scan images, may predict which small AAAs are more prone to rapid expansion.

Aortic Aneurysm, Abdominal↗

PubMed1994

Performance of the vascular physical examination by residents and medical students.

PURPOSE: This study uses an objective structured clinical examination to evaluate the performance and interpretation of the vascular physical examination by interns and medical students. METHODS: A patient with lower extremity arterial occlusive disease findings was examined by 20 third-year students (M3), 23 physicians entering surgical internship (PGY1), and 7 individuals completing internship (PGY2). The test consisted of two sections: part A evaluated the individuals' ability to perform a pulse examination (data gathering); part B evaluated the interpretation of the physical examination findings (data interpretation). National Board of Medical Examiners Part II examination results were obtained for 84% of participants. RESULTS: All groups performed poorly, with overall correct percent scores being 43% (M3), 39% (PGY1), and 62% (PGY2). PGY2s performed significantly better than M3s or PGY1s (p = 0.0002). No statistical difference was noted between M3 and PGY1 scores. Overall, data gathering skills were significantly better than data interpretation skills (51% vs 37%, p = 0.0001). National Board of Medical Examiners Part II scores did not vary substantially among groups. CONCLUSIONS: Interns and medical students demonstrated considerable inaccuracy in both data gathering and data interpretation. A modest improvement was observed in individuals tested at the end of the internship year. This study suggests that increased attention should be directed toward instructing surgical residents and students how to perform an accurate peripheral vascular physical examination and how to interpret its significance.

Arterial Occlusive Diseases↗

PubMed1993

Thromboembolic complications of polycythemia: polycythemia vera versus smokers' polycythemia.

PURPOSE: This report compares patients with the hypercoagulable state of polycythemia vera to patients with secondary polycythemia caused by tobacco use to determine whether the incidence of thromboembolic events is equivalent. METHODS: The medical records of 146 patients with the diagnosis of polycythemia between 1977 to 1990 were reviewed. Patients with transient, relative, or stress polycythemia were excluded from this study as were patients with polycythemia as a result of cardiac or pulmonary anomalies or both. The diagnosis of polycythemia vera (n = 43) was verified by use of the guidelines of the Polycythemia Vera Study Group. The diagnosis of polycythemia caused by smoking (n = 27) was based on an elevated total red blood cell volume, decreased oxygen saturation on arterial blood gas measurement, evidence of chronic obstructive pulmonary disease, and elevated carboxyhemoglobin levels. RESULTS: Twenty-six patients (60%) with polycythemia vera and 11 patients (41%) with smoker's polycythemia had at least one thromboembolic problem. No significant differences existed between the groups with regard to age, hematocrit, or number of cardiac and cerebrovascular events. Overall, patients with polycythemia vera had a greater number of thromboembolic events per patient (p < 0.05) and more peripheral arterial thromboemboli (p < 0.005) than did patients with polycythemia as a result of smoking (Fisher's Exact Test). CONCLUSIONS: Thus the results of this study demonstrate that smokers' polycythemia does not represent a hypercoagulable state equivalent to that of polycythemia vera.

Analysis of Variance↗

PubMed1992

Recognition of arterial injury in elbow dislocation.

The clinical presentation of patients with elbow dislocations was reviewed to identify those factors indicating an increased risk for arterial injury. Sixty-two patients were treated for 63 elbow dislocations between January 1981 and July 1991. Eight patients (13%) sustained a concomitant arterial injury involving the brachial (7) and radial (1) arteries. Three clinical findings, absence of a radial pulse, open dislocation, and presence of systemic injuries, were correlated with arterial injury. A palpable radial pulse was absent in six (75%) patients with an arterial injury but in only two (4%) with normal vessels (p less than 0.0001, chi square). Five (33%) open dislocations had an associated arterial injury, whereas three (6%) arterial injuries occurred in closed dislocations (p less than 0.006, chi square). Systemic injury occurred in five dislocations (63%) with arterial injuries and 14 dislocations (25%) without arterial injury (p less than 0.04, chi square). Multivariate analysis showed that absence of a radial pulse was the only factor that significantly predicted arterial injury (p less than 0.0001). Although most elbow dislocations are not associated with arterial injury, absence of a radial pulse or presence of an open dislocation or both should alert the clinician to the increased possibility of an associated vascular injury.

Adult↗

PubMed1991

Intimal hyperplasia is reduced by ornithine decarboxylase inhibition.

Polyamines are intracellular cations that are thought to play a role in the regulation of cell growth and differentiation. This study was undertaken to determine if inhibition of ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine synthesis, suppresses formation of intimal hyperplasia (IH) after arterial injury. Twenty New Zealand white rabbits underwent balloon catheter deendothelialization of a common carotid artery. Treated animals (n = 10) were given alpha-difluoromethylornithine (DFMO), an inhibitor of ODC, ad lib in drinking water as a 2% solution. DFMO was begun 3 days prior to surgery and continued until vessel harvest. Vessels were perfusion-fixed at harvest, 2 (n = 10) and 4 (n = 10) weeks postoperatively. All arteries remained patent. There were no histologic differences in the IH between treated and untreated animals. The intima and media surface areas on serial arterial cross sections were determined using computer-assisted planimetry. There was a significant difference in the IH surface area of injured arteries between untreated and DFMO-treated animals at both 2 (17.6 +/- 2.0 vs 3.0 +/- 1.6 microns 2; P less than or equal to 0.001) and 4 weeks 27.4 +/- 5.6 vs 7.1 +/- 1.8 microns 2; P less than or equal to 0.008). No differences were seen in medial thickness. We conclude that ODC inhibition reduces early development of IH after arterial deendothelialization. These data support the hypothesis that polyamines may be cellular messengers involved in the regulation of IH formation.

Animals↗

PubMed1991

Effects of hypercholesterolemia on healing of vascular grafts.

Small-diameter vascular grafts woven from bioresorbable lactide/glycolide copolymers have been successfully interposed into aortas of normal NZW rabbits. The current study examines the histologic and functional reactions to these bioresorbable grafts in severely hypercholesterolemic rabbits, a standard animal model of atherosclerosis. Sixty rabbits were placed on a 2% cholesterol, 6% peanut oil atherogenic diet. Baseline serum cholesterols and triglycerides were measured and repeated at operation 3 months later. Woven polyglactin 910 (PG910) grafts were interposed into infrarenal aortas. Fifty-two rabbits died on the diet or within 3 days of surgery and eight survived operation (normal NZW rabbit operative mortality is less than 10%). Cholesterol levels rose from 63 to 1989, p less than .001. Of the eight survivors, five died after 3 weeks, and one died after 2 1/2 months. Two were sacrificed at 2 and 4 months. Four aortic disruptions with retroperitoneal hematomas, one pseudoaneurysm, and one diffuse aneurysm were observed, greater than in normal rabbits, p less than .001. Inspection revealed severe atherosclerosis. Histologically, 3-week explants showed only small areas of neointima with myofibroblasts and endothelial cells; the outer capsules were infiltrated by lipid-laden macrophages. Graft material in 2- to 4-month explants was replaced by tissue with histologic atherosclerosis. More severe atherosclerosis was observed in native aortas at the perianastomotic areas than the more distant aortic segments. Abundant intracellular lipid was seen also in splenic histiocytes and hepatic cells with evidence of micronodular cirrhosis. Macrophages phagocytizing bioresorbable prostheses may release growth factors mediating the formation of a cellular tissue conduit. Severe hypercholesterolemia may alter monokine release from macrophages resulting in a weakened prosthesis/tissue complex.

Animals↗

PubMed1991

Thallium redistribution does not predict perioperative cardiac complications following vascular surgery.

Utility of preoperative stress thallium scintigraphy (STS) was determined in 59 patients, thought to be at increased risk, prior to major vascular surgery from July 1987 to February 1990. Forty-seven had oral dipyridamole and 12 underwent exercise STS. Thallium redistribution (TR) was present in 61% (n = 36); fixed defects were present in 59% (n = 35); and some combination of defects was present in 76% (n = 45). Perioperative cardiac complications (CC = congestive heart failure [n = 3], ventricular arrhythmia [n = 2], and MI [n = 1]) were present in 8.5% (6 CC in 5 patients). Incidence of CC was 8.3% (3/36) in those with TR, and 8.7% (2/23) without TR (relative risk = 0.95). Perioperative MI was present in 2.8% (1/36) with TR vs. 0% (0/23) without. Though mortality was 3.4%, no perioperative deaths were from cardiac disease. Utility of STS is not clearly established for prediction of perioperative cardiac risk after major vascular surgery.

Adult↗

PubMed1991

Hip disarticulation: factors affecting outcome.

Hip disarticulation, especially in patients with peripheral vascular disease, has been associated with high morbidity and mortality rates. This report describes patient characteristics that influence the clinical outcome of hip disarticulation. The medical records of all patients undergoing hip disarticulation from 1966 to 1989 were reviewed for surgical indication, perioperative wound complications, and postoperative deaths. Fifty-three patients underwent hip disarticulation for limb ischemia (10), infection (12), infection and ischemia (14), or tumor (17). The overall incidence of wound complications was 60%, and no significant differences were found among the groups. Prior above-knee amputation and urgent/emergent operations were significantly associated with increased wound complications (p less than 0.05). The overall mortality rate was 21%, ranging from 0% (tumor) to 50% (ischemia) and differed significantly among the groups (p less than 0.02). Mortality was significantly associated with urgent/emergent operations (p less than 0.01). Age, diabetes mellitus, and previous inflow procedures did not influence mortality rates. The presence of limb ischemia influenced mortality rates to a greater extent than did infection, and a history of cardiac disease was statistically predictive of death. Wound complications frequently accompanied hip disarticulation, regardless of operative indication, and were significantly increased by urgent/emergent operations and prior above-knee amputation. Hip disarticulation can be performed with low mortality rates in selected patients. Both limb ischemia and infection substantially increase operative mortality rates.

Adult↗

PubMed1989

Hemodynamic effects on endothelial cell monolayer detachment from vascular prostheses.

The establishment of an early blood-contacting endothelialized surface may improve the graft-host relationship. This study evaluated the adherence of indium 111-radiolabeled endothelial cells that were cultured to confluence on fibronectin-treated polyester elastomer (Hytrel) grafts that were perfused for two hours on a pulse duplicator apparatus under high- and low-shear conditions. Perfusate samples were serially assayed for radioactivity. After perfusion, grafts were sectioned into four segments and assayed for retained radioactivity. All graft segments were hematoxylin stained and examined under light microscopy for evaluation of cell density. Excellent endothelial cell adherence (90%) was observed under both hemodynamic conditions at 120 minutes, with most losses occurring within the first 15 minutes. No differences were seen between high- and low-shear conditions or proximal vs distal graft segments.

Animals↗

PubMed1989

Macrophage/biomaterial interactions: the stimulation of endothelialization.

This current study analyzed macrophage/biomaterial interactions as modulators of endothelial cell proliferation. Rabbit peritoneal macrophages were harvested and seeded (1 x 10(6) cells/ml) into culture flasks with Dulbecco's modified Eagle medium and 10% platelet-poor, plasma-derived equine serum. Macrophages were identified by morphologic characteristics, nonspecific esterase, and Fc (immunoglobulin G) receptors on the cell membranes. Culture conditions were (1) no prosthetic material, (2) Dacron, or (3) Polyglactin 910 (PG910) (Ethicon, Inc., Somerville, N.J.). Both prosthetic materials were finely shredded into the media. After 5 weeks in culture, PG910 inclusions were seen within macrophage cytoplasm. No intracytoplasmic Dacron was observed. Conditioned media from all three groups were collected weekly from week 5 to week 10, centrifuged, filtered, and added in serial dilutions to cultured quiescent murine capillary lung endothelial cells. Quiescence was achieved by serum deprivation and verified by [3H]thymidine incorporation. Sixteen hours after addition of conditioned media, [3H]thymidine was measured in and expressed as percent increase above quiescent levels. Mitogenic activity in the PG910 group progressively increased from weeks 6 to 10. At week 10, the PG910 group (1:10 dilution) yielded a 620% increase in DNA synthesis. The Dacron group never varied from the control group (no prosthetic). The mean increases in [3H]thymidine incorporations over weeks 7 to 10 were PG910, 540% +/- 65%; Dacron, 323% +/- 65%, and control, 343% +/- 26% (PG910 vs Dacron, p less than or equal to 0.004). These studies suggest macrophage activation by bioresorbable prostheses, yielding growth factor release with subsequent enhanced endothelial cell proliferation.

Animals↗

PubMed1989

Effect of twist on flow and patency of vein grafts.

This article examines the effect of twist on flow through reversed vein segments in vitro and its effect on graft patency in vivo. Excised canine superficial femoral veins were perfused in vitro with normal saline solution or canine blood. Perfusion was carried out at five pressures and against three outflow resistances. Increasing increments of twist were applied to the outflow end of the vein. Flow was measured at each level of twist. With both saline solution and blood, flow was unaltered until twist reached 140 to 180 degrees. Flow then decreased sharply, stopping completely at 175 to 200 degrees of twist. In vivo experiments were then performed in 13 dogs. Reversed superficial femoral veins were used as end-to-end grafts to bypass the iliac arteries. Each graft was deliberately twisted 0, 45, 90, 135, or 200 degrees. All grafts were harvested 6 months after surgery. Eighteen of 20 grafts twisted 135 degrees or less remained patent. However, all five grafts twisted 200 degrees were thrombosed within 4 hours of surgery (p less than 0.05). These data suggest that in patients a slight amount of graft twist probably does not reduce flow; however, more than 135 degrees of twist will greatly reduce flow, leading to early graft thrombosis.

Animals↗