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Biomedical subjects

V Gahtan

Publications and source records attributed to V Gahtan.

At least 37 records · Page 2Linked to original sources
PubMed1998

Thrombospondin-1 is elevated with both intimal hyperplasia and hypercholesterolemia.

BACKGROUND: Thrombospondin-1 (TSP-1) is important in platelet adhesion and aggregation, inflammation, cell to cell interaction, angiogenesis, and smooth muscle cell (SMC) proliferation. TSP-1 expression increases rapidly with injury. Therefore, we hypothesize that TSP-1 may play a role in the development of intimal hyperplasia (IH). The purpose of this study is to examine the interaction between cholesterol and TSP-1 on SMC proliferation and to quantitatively assess TSP-1 expression in an established model of IH, with and without underlying cholesterol-induced atherosclerosis. MATERIALS AND METHODS: In vitro, rabbit aortic SMC culture studies were performed to see the effect of TSP-1 antibodies on PDGF and, separately, cholesterol-induced SMC proliferation. In vivo, 23 rabbits were fed either a regular or a high-cholesterol diet. Hypercholesterolemia was confirmed by measurement of serum levels. Subsets underwent intraluminal aortic injury. Aortas were harvested 8-10 weeks later. Arterial wall TSP-1 was evaluated immunohistochemically and quantified by computer image analysis. RESULTS: In vitro, TSP-1 antibodies were able to inhibit PDGF and cholesterol-induced SMC proliferation (P < 0.05). In vivo, TSP-1 was found predominantly in the extracellular matrix in the rabbit aorta. IH was uniformly seen status-post angioplasty. Hyperplasia was more prominent in samples from hypercholesterolemic animals. ANOVA and Student's t test analyses demonstrated significantly more TSP-1 in the high-cholesterol/angioplasty group than in all other groups (P = 0.0006 vs regular diet/no angioplasty group). CONCLUSIONS: These data are consistent with the hypothesis that TSP-1 contributes to the development of IH. This study suggests that injured arteries in hypercholesterolemic atherosclerotic rabbits overexpress TSP-1.

Animals↗
PubMed1998

Carotid endarterectomy outcome is not affected in patients with a contralateral carotid artery occlusion.

BACKGROUND: The purpose of this retrospective patient/control patient study was to determine perioperative risk and long-term benefits of carotid endarterectomy contralateral to an occluded internal carotid artery. METHODS: Thirty-seven patients undergoing carotid endarterectomy contralateral to an occluded internal carotid artery were each paired with two control group patients (n = 74) undergoing carotid endarterectomy contralateral to a patent internal carotid artery. Patients preferentially underwent electroencephalographic monitoring, selective shunting, and patch angioplasty for vessel closure. RESULTS: The perioperative rate of stroke or death was 5% (n = 2) in the occluded group and 3% (n = 2) in the control group. Ninety-two percent of the occluded group and 96% of the control patients were stroke-free over a mean follow-up of 23.8 and 27.2 months, respectively. No statistical difference was noted between groups for perioperative rate of stroke or death (P = 0.60), mean stroke-free rates (P = 0.37), stroke rate by life-table analysis (P = 0.33), or survival by life-table analysis (P = 0.43). CONCLUSIONS: Patients who have carotid endarterectomy performed contralateral to an occluded internal carotid artery showed no difference for perioperative stroke or death, late stroke, or survival.

Aged↗
PubMed1998

The noninvasive vascular laboratory.

The noninvasive vascular laboratory is an important resource in the management of patients with peripheral vascular disease. The commonly accepted uses of the vascular laboratory, including both indirect testing (segmental limb pressures, waveform analysis, digital pressures, exercise testing, reactive hyperemia) and direct vascular testing with CDI, have been reviewed. These techniques have changed how these patients are diagnosed, with less need for invasive diagnostic techniques. Patient management and intervention have also been altered by these advances. The use of noninvasive techniques and continue progress in this area should continue to advance patient care.

Amputation, Surgical↗
PubMed1998

Determination of carotid plaque risk by ultrasonic tissue characterization.

This in vitro study investigated the ability of ultrasonic tissue characterization (UTC) to discriminate between plaques from asymptomatic and symptomatic patients and to compare UTC findings with quantitative measurements of plaque morphology. A total of 34 plaque specimens removed at carotid endarterectomy were scanned transversely at intervals of 1 mm, and compared to tissue cross-sections examined by optical microscopy employing computer-assisted planimetry. UTC was performed by spectral analysis of backscattered radiofrequency signals. The slope, intercept and total power parameters of the spectrum were evaluated. Discriminant analysis was used to compare the ability of the UTC spectral parameters and morphological constituents to correctly classify plaques according to their symptom group membership. UTC correctly classified 88.2% of the plaques. Thrombus was present in 93.9% of the plaques, and there was little difference in the morphological constituents of plaques from asymptomatic and symptomatic patients. Morphological constituents correctly classified 60.7% of the plaques. We conclude, in this preliminary study, that UTC can discriminate between carotid plaques from asymptomatic and symptomatic patients with moderate accuracy, despite a similarity in their morphological composition. UTC discrimination is not related to differences in the type or amount of morphological constituents in the plaques.

Carotid Arteries↗
PubMed1998

Does renal failure influence infrainguinal bypass graft outcome?

The purpose of this study is to determine the role of renal failure (RF) in infrainguinal bypass graft outcome. From 1990 through 1996, 206 patients underwent 241 infrainguinal bypass grafts at two institutions. Thirty-three RF patients (42 bypasses) had a mean follow-up of 14.0 months and a mean age of 67.7 years, and 21 (64%) were male. Risk factors included hypertension (100%), diabetes (81.8%), and cardiac disease (75.8%). RF patients included 20 with end-stage renal disease (ESRD) and 14 with renal insufficiency (RI). One patient had RI during his first bypass and ESRD for his subsequent bypass. The major operative indication was limb salvage (90.5%). Total perioperative morbidity for ESRD was significantly higher than for RI and non-RF groups (P = 0.019). Early mortalities occurred in three ESRD, no RI, and seven non-RF patients. Life table analysis demonstrated no significant difference between primary patency (P = 0.56), secondary patency (P = 0.96), and limb salvage (P = 0.69) between ESRD and non-RF groups. However, there was an overall decreased survival rate in the ESRD group (P < 0.01). In conclusion, infrainguinal vein bypass grafting can be successfully performed in RF patients with comparable patency and limb salvage rates and therefore improve quality of life. However, perioperative morbidity was higher in ESRD and survival was significantly shorter for RF than for non-RF patients.

Aged↗
PubMed1998

Efficacy of anticoagulation post-inferior vena caval filter placement.

Anticoagulation with heparin or Coumadin is usually effective in the management of deep vein thrombosis; however, if anticoagulation treatment is contraindicated, is ineffective, or leads to adverse effects, inferior vena caval (IVC) placement of a filter is indicated. The purpose of this study is to determine whether increased early adverse effects are present in patients not given anticoagulation medication after placement of an IVC filter. The records of 240 consecutive patients who received IVC filter placement were reviewed for indications for placement, as well as for whether patients received anticoagulation medication on discharge. There were 41 in-patient mortalities. Of the remaining 199 patients, 100 were discharged and prescribed anticoagulation medication, and 99 were not. Patients were followed for 3 to 60 months. These results suggest that no early adverse effects are seen in patients who are not given anticoagulants after IVC filter placement.

Adult↗
PubMed1998

Understanding molecular biology.

Vascular disease is more commonly being studied at a molecular level. The knowledge derived is being applied to our understanding of clinical vascular disease processes and reconstruction outcome. Furthermore, applications are increasingly found for diagnosis and even intervention. The fundamental concepts and techniques involved in molecular biology are presented.

Animals↗
PubMed1997

Toe amputation in the diabetic patient.

BACKGROUND: We considered whether it is more practical to amputate the toe of a diabetic patient with osteomyelitis and good circulation or to treat the patient with antibiotics for a prolonged period. METHODS: We undertook a retrospective study of 141 diabetic patients who had undergone a toe-ray amputation for proven or documented osteomyelitis. RESULTS: The mean ankle/brachial index of all patients was 0.81 (range, 0.68 to 1.14); the mean functional days lost on antibiotic therapy was 39 (range, 7 to 84 days). The cost of 6 to 8 weeks of preoperative antibiotic therapy was $900 to $2240 (mean, $1440). CONCLUSIONS: Diabetic patients with good circulation and osteomyelitis of the toe may benefit from prompt toe amputation.

Amputation, Surgical↗
PubMed1997

Carotid plaque typing by multiple-parameter ultrasonic tissue characterization.

We evaluated the ability of ultrasonic tissue characterization (UTC), based on backscattered echo signals, to distinguish among the components of advanced carotid plaques. We performed spectral analysis of echo signals acquired from human carotid endarterectomy specimens in vitro to calculate three parameters of the calibrated power spectrum: slope, intercept and total power for fibrous, lipid pool and thrombus constituents of plaque. Plaque constituents were identified histologically. We evaluated classification efficacy by discriminant function analysis. Slope and intercept parameters alone provided correct classification in 92.5%, 57.6% and 72.4% of fibrous, lipid pool and thrombus plaque components, respectively. Slope, intercept and total power used in combination improved classification of the three tissue types to 93.0%, 69.7% and 81.0%. The overall proportion of correctly classified tissue regions increased from 84.5% to 88.0% by the combined use of the three parameters. The improvement in classification that occurred when we included total power as a third parameter suggests that ultrasound plaque components may not consist solely of small, randomly distributed isotropic scatterers. Our ability to identify plaque thrombi provides motivation for future studies of parameter-based imaging methods for identifying such plaque that presents an increased risk of embolic neurologic ischemic events.

Arteriosclerosis↗
PubMed1997

Body composition and source of weight loss after bariatric surgery.

BACKGROUND: Little is known about the composition and source of weight loss after bariatric surgery for morbid obesity. PURPOSE: This study was undertaken to determine changes in weight, body mass index (BMI), lean body weight (LBW), fat weight (FW) and left ventricular cardiac mass (LVM) following vertical banded gastroplasty (VBG). METHODS: After VBG for morbid obesity, 26 women and four men (mean age = 39.1 years) were weighed and had body composition analysis undertaken at intervals. Thirteen patients underwent echocardiography preoperatively and 1 year postoperatively to determine change in LVM and LVM index. RESULTS: Over 12 months there was significant weight loss for all weight parameters examined (p < 0.05). Fat weight loss was most significant; total weight loss and reduction of BMI were significant but less so than fat loss (Wilcoxon's signed ranks test). LBW loss had the smallest contribution to weight loss (p < 0.0001). There was a significant loss of LVM and posterior cardiac wall thickness (p < 0.05). CONCLUSIONS: VBG can lead to loss of lean body weight and left ventricular mass, and more dramatically, fat weight, body weight, and BMI. Cardiac mass and lean body mass are preferentially conserved relative to body fat with weight loss after VBG.

Adult↗
PubMed1997

In vivo detection of carotid plaque thrombus by ultrasonic tissue characterization.

The purpose of the study was to determine whether ultrasonic tissue characterization could detect carotid plaque thrombus in vivo. Patients undergoing carotid endarterectomy were examined preoperatively and the ultrasonic tissue characterization findings were compared to those of optical microscopy of the removed plaque specimens. Ten of 15 patients studied had plaque thrombus. Ultra-ultrasonic tissue characterization entailed an analysis of parameters obtained from the power spectrum of backscattered ultrasound signals. Data were obtained with a nominal 10 MHz sector scanning transducer with an effective bandwidth of 3 to 13 MHz. The parameters were the slope and intercept derived from the linear regression of the normalized spectrum and total power (log of the integrated power of the normalized spectrum over the effective bandwidth). The combined effect of the three parameters was determined by discriminant function analysis and showed a significant difference (P < 0.05) between nonthrombus and plaque thrombus in a small sample of patients with advance carotid atherosclerosis. These parameters applied singly could not provide such a distinction. Correct classification of carotid plaque thrombus using the multiple-parameter analysis revealed a sensitivity of 90%, specificity of 80%, and accuracy of 86.7%. This study demonstrates that analysis utilizing a combination of multiple spectral parameters was able to detect carotid plaque thrombus in vivo.

Aged↗
PubMed1996

Neurofibromatosis and arterial aneurysms.

Neurofibromatosis (NF) is a common autosomal dominant disease characterized by the development of hamartomatous or neoplastic lesions due to the proliferation of neural crest cells. An association of aneurysmal arterial lesions with NF, which may have catastrophic complications, has been rarely reported. Our recent experiences with the diagnosis and management of three male NF patients with aneurysms is described. A 19-year-old-man with refractory hypertension due to unilateral, complex, unreconstructable renal artery aneurysms was successfully treated by nephrectomy. Histopathology demonstrated intramural renal artery Schwann cell proliferation. A 44-year-old patient underwent ligation of a ruptured superior mesenteric artery aneurysm. Finally, a femoral-popliteal artery saphenous vein bypass graft with aneurysm exclusion was performed in a 58-year-old-man with a 3.5 cm symptomatic popliteal artery aneurysm. In NF, the underlying pathology in large arteries is intramuscular Schwann cell proliferation with secondary fibrosis. Mesodermal dysplasia may affect small arteries resulting in stenosis, post-stenotic dilatation, or aneurysmal degeneration. Clinicians should be aware of the unusual association of NF with aneurysms, particularly the occult development of visceral and renal artery aneurysms. These lesions are subject to sudden rupture with potentially devastating consequences, and they mandate a high index of suspicion in NF patients.

Adult↗
PubMed1996

Popliteal artery injury after total knee arthroplasty.

Total knee arthroplasty (TKA) is a commonly performed orthopedic procedure. The incidence of vascular complications after TKA is low. However, these complications may be debilitating, limb-threatening, and potentially avoidable. Our first patient, who had no preexisting vascular occlusive disease, developed an ischemic extremity after TKA. The second patient underwent TKA and was diagnosed with a severely ischemic limb 48 hours postoperatively. Both patients underwent above-knee to below-knee popliteal artery saphenous vein bypass grafting. Although limb salvage was obtained in both cases, one had a significantly neuropathic foot. In conclusion, long-term morbidity can be avoided by early identification and treatment of ischemia by bypass grafting.

Aged↗
PubMed1995

Antistaphylococcal activity of rifampin-bonded gelatin-impregnated Dacron grafts.

The affinity of rifampin to bond to Dacron permits implantation of a vascular prosthesis with anti-staphylococcal bioactivity. The performance of rifampin-bonded Dacron grafts was evaluated in vitro and in vivo to develop a bonding technique with optimal graft bioactivity which was then used for in situ reconstruction of a biofilm graft infection. In vitro bioactivity was measured at 24-hr intervals for three types of Dacron prostheses (plain, gelatin, and collagen-impregnated) exposed to rifampin at varied concentrations and immersion times. Gelatin-impregnated grafts demonstrated superior bioactivity (P < 0.05). Rifampin concentration and graft type had a greater effect on bioactivity than immersion time (P < 0.01). Gelatin-impregnated grafts immersed in a 60 mg/ml rifampin solution for 15 min produced optimum bioactivity. Six grafts prepared in this fashion were used to replace the canine aorta. The level and duration of in vivo antistaphylococcal activity to Staphylococcus aureus and Staphylococcus epidermidis were less (P < 0.05) than those measured in vitro, but rifampin levels exceeded the study strain maximum inhibitory concentration for up to 48 hr. In a canine model, the rifampin-bonded gelatin-impregnated (N = 14) or nonbonded control (N = 10) grafts were used as in situ replacement for an established aortic graft infection caused by S. epidermidis. Replacement with a rifampin-bonded graft resulted in successful anatomic healing of perigraft and anastomotic tissue. Persistent biofilm colonization was confirmed in 8 of 10 controls versus 4 of 14 rifampin-bonded grafts (P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

The origin of infrainguinal vein graft stenosis: a prospective study based on duplex surveillance.

PURPOSE: The purpose of this study was to determine the origin of vein graft lesions and their propensity for progression based on prospective duplex surveillance of 135 infrainguinal vein bypasses. METHODS: One hundred sixteen greater saphenous, 13 spliced, five cephalic, and one superficial femoral vein grafts were evaluated by color duplex imaging at surgical procedure, 1 and 6 weeks, 3 and 6 months, and every 3 to 6 months thereafter. Duplex-identified lesions were graded by peak systolic velocity and velocity ratio criteria and were either followed or subjected to revision. RESULTS: Early postoperative duplex surveillance allowed stratification of infrainguinal grafts into two subsets. Of 91 (67%) grafts with normal early scans (at 3 months), only two (2.2%) developed de novo stenoses (at 6 and 8 months) that required revision. Forty-four grafts with abnormal duplex scans had a focal flow abnormality (peak systolic velocity > 150 cm/sec, velocity ratio > 1.5) in the graft body (n = 24) or anastomotic region (n = 20). In 14 grafts the flow abnormality (mean peak systolic velocity = 217 cm/sec, velocity ratio = 2.3) normalized. Ten additional grafts exhibited a moderate, persistent graft stenosis (mean peak systolic velocity 248 cm/sec, velocity ratio = 3.3) that was not repaired. All 20 grafts with lesions that progressed to high-grade stenosis (mean peak systolic velocity = 362 cm/sec, velocity ratio = 7.2) and were revised had a residual flow abnormality confirmed at operation, or it appeared by 6 weeks. In the entire series six (4.4%) grafts failed during the mean 12-month follow-up interval (range 3 to 30 months), 4 with unrepaired defects and two after revision. CONCLUSIONS: Prospective duplex surveillance verified that de novo graft stenosis was uncommon (< 2.2%) after reversed and in situ saphenous vein bypass grafting. Graft stenoses developed at sites of unrepaired defects or early appearing conduit abnormalities. An early appearing duplex focal flow abnormality warranted careful surveillance, because one half of such sites progressed to a high-grade stenosis. Grafts with normal early duplex scans exhibited a low incidence of stenosis development or occlusion, and thus less intense postoperative surveillance can be recommended.

Adult↗
PubMed1995

Occult vascular injuries following gunshot wounds resulting in long bone fractures of the extremities.

The routine use of arteriography following penetrating injuries to the extremities has declined in popularity in recent years. A careful physical examination coupled with Doppler-derived blood pressure has been shown to be sufficient to determine the presence of significant vascular injuries in most circumstances. Evaluating for occult vascular injuries in the presence of a complex wound involving the fracture of a long bone, however, seems to be an exception to this trend in management. This study was undertaken to ascertain the incidence of occult versus clinically apparent vascular injuries in patients suffering gun shot wounds (GSW) to the extremities that were associated with a long bone fracture. To address the value of invasive arteriographic evaluation, physical examination (pulse palpation, Doppler-derived limb blood pressure) was compared to arteriography in 75 consecutive patients following a GSW that resulted in fracture of the tibia/fibula (n = 28), femur (n = 19), humerus (n = 17), or radius/ulna (n = 11). Fourteen patients (19%) had an abnormal physical examination, with 13 (93%) of these also having an abnormal arteriogram. Of the 61 (81%) patients with a normal physical examination, an occult vascular injury was found on subsequent arteriography in 17 (28%). These occult injuries were classified as minor (intimal flap less than one-fourth the diameter of the vessel, segmental narrowing, noncritical branch vessel injury) or major (large intimal flap, occlusion, pseudoaneurysm, A-V fistula). The majority (83%) of occult injuries were minor and did not require operative intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Intraoperative duplex scanning of arterial reconstructions: fate of repaired and unrepaired defects.

PURPOSE: Because unrecognized lesions can cause an arterial reconstruction to fail, duplex ultrasonography was evaluated as an intraoperative aid to assess technical adequacy and provide criteria for which lesions should be repaired immediately versus safely followed. METHODS: Since 1990 intraoperative color duplex scanning(7 to 10 MHz linear array probe, pulsed-wave Doppler test spectrum analysis) was used to assess the frequency and severity of residual lesions in 368 patients after carotid endarterectomy (n = 210), infrainguinal vein bypass (n=135) or visceral/renal reconstruction (n = 23). Duplex scan results were categorized as normal or abnormal, with immediate repair of lesions demonstrating both lumen reduction and severe focal flow abnormalities (peak systolic velocity [Vp] > 150 to 180 cm/sec;velocity ratio [Vr] > 2.4). Arteriography was also performed in 81% of lower limb bypass procedures. RESULTS: Duplex scanning identified technical (residual plaque, stricture) or intrinsic defects (platelet thrombus, distal thrombosis) requiring revision in 37 (10%) of the reconstructions. Infrainguinal bypass had the highest incidence of corrected defects (14%) and adverse events (3%). No adverse events occurred in patients with normal duplex scan results or after carotid endarterectomy. Overall, 76% of identified defects were corrected (carotid, 17 of 24; infrainguinal bypass, 19 of 24; visceral bypass, 1 of 1). Unrepaired flow defects (Vp = 150 to 190 cm/sec; Vr = 1.8 to 2.5) led to one graft occlusion and three early revisions. Postoperative duplex scanning demonstrated residual stenosis in seven of 12 patients with unrepaired defects, two of 36 patients with repaired defects, and five of 312 patients with normal scan results (p < 0.001). CONCLUSION: Based on the types of lesions corrected and the low (< 0.5%) complication rate after a normal or modified arterial reconstruction, duplex scanning was found to be a valuable intraoperative aid. Unrepaired defects require close surveillance for progression.

Algorithms↗