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Biomedical subjects

J Blebea

Publications and source records attributed to J Blebea.

At least 19 recordsLinked to original sources
PubMed2000

Opioid growth factor modulates angiogenesis.

OBJECTIVE: Induced angiogenesis has recently been attempted as a therapeutic modality in patients with occlusive arterial atherosclerotic disease. We investigated the possible role of endogenous opioids in the modulation of angiogenesis. METHODS: Chick chorioallantoic membrane was used as an in vivo model to study angiogenesis. Fertilized chick eggs were incubated for 3 days, explanted, and incubated for an additional 2 days. Three-millimeter methylcellulose disks were placed on the surface of the chorioallantoic membrane; each disk contained opioid growth factor ([Met(5)]-enkephalin; 5 microgram), the short-acting opioid receptor antagonist naloxone (5 microgram), opioid growth factor and naloxone together (5 microgram of each), the long-acting opioid antagonist naltrexone (5 microgram), or distilled water (control). A second series of experiments was performed with distilled water, the angiogenic inhibitor retinoic acid (1 microgram), and vascular endothelial growth factor (1 microgram) to further evaluate our model. The developing vasculature was imaged 2 days later with a digital camera and exported to a computer for image analysis. Total number of blood vessels, total vessel length, and mean vessel length were measured within a 100-mm(2) region surrounding each applied disk. Immunocytochemical analysis was performed with antibodies directed against opioid growth factor and its receptor (OGFr). RESULTS: Opioid growth factor had a significant inhibitory effect on angiogenesis, both the number of blood vessels and the total vessel length being decreased (by 35% and 20%, respectively) in comparison with control levels (P <.005). The simultaneous addition of naloxone and opioid growth factor had no effect on blood vessel growth, nor did naloxone alone. Chorioallantoic membranes exposed to naltrexone displayed increases of 51% and 24% in blood vessel number and length, respectively, in comparison with control specimens (P <.005). These results indicate that the opioid growth factor effects are receptor mediated and tonically active. Immunocytochemistry demonstrated the presence of both opioid growth factor and OGFr within the endothelial cells and mesenchymal cells of the developing chorioallantoic membrane vessel wall. Retinoic acid significantly reduced the number and the total length of blood vessels, whereas vascular endothelial growth factor increased both the number and the length of blood vessels in comparison with the controls (P <.0001). The magnitude of opioid growth factor's effects were comparable to those seen with retinoic acid, whereas inhibition of opioid growth factor with naltrexone induced an increase in total vessel length comparable to that for vascular endothelial growth factor. CONCLUSIONS: These results demonstrate for the first time that endogenous opioids modulate in vivo angiogenesis. Opioid growth factor is a tonically active peptide that has a receptor-mediated action in regulating angiogenesis in developing endothelial and mesenchymal vascular cells.

Allantois↗
PubMed1999

Risk factors and outcomes following revascularization for chronic mesenteric ischemia.

Revascularization for chronic mesenteric ischemia is an infrequent vascular procedure whose objective long-term patency results have been described in relatively few patients. We reviewed our experience with such procedures and report on the objective and symptomatic long-term results. We retrospectively reviewed a consecutive series of 42 patients who underwent mesenteric arterial reconstruction of 66 vessels during an 11-year period from 1986 to 1997. All patients were treated for symptomatic chronic mesenteric ischemia. The results support the clinical efficacy and durability of visceral artery bypass procedures for patients with symptomatic chronic mesenteric ischemia. Patency rates for females were better than for males independent of graft type.

Angioplasty↗
PubMed1999

Deep venous thrombosis after percutaneous insertion of vena caval filters.

PURPOSE: A large multicenter study has recently questioned the overall clinical efficacy of vena caval filters, especially when inserted prophylactically, because of the subsequent development of deep venous thrombosis (DVT) at the insertion site. We examined the incidence of this complication with newer, smaller diameter percutaneous devices. METHODS: We reviewed our vascular surgery and interventional radiology clinical registries to identify patients in whom a femoral percutaneous vena caval filter had been placed from 1993 to 1998. This list was cross referenced with patients who had undergone lower extremity venous ultrasound scan examinations for the diagnosis of DVT in the vascular laboratory within a 60-day period before and after the insertion of the filter device. RESULTS: A total of 35 patients during this 5-year period had timely follow-up venous duplex scan studies performed. The indications for filter placement were DVT in 16 patients (46%), pulmonary embolus in 13 patients (37%), DVT and pulmonary embolus in three patients (9%), and prophylactically in three patients (9%) at high risk for thromboembolization. Of the patients with documented thromboembolic events, 91% (29 of 32) had contraindications to anticoagulation therapy, and the remaining 9% (3 of 32) represented failure of anticoagulation therapy. A Greenfield filter was used in 13 patients (37%), a Simon Nitinol filter was used in 11 patients (31%), and a VenaTech filter was used in nine patients (26%). The other two patients (6%) had a Bird's Nest filter inserted. At a mean follow-up period of 12 +/- 2 days (median, 6 days), there was a 40% (14 of 35) incidence of proximal DVT in venous segments without evidence of thrombus before filter insertion. The majority (71%; 10 of 14) occurred in the common femoral vein, with three located in the superficial femoral vein and one in the external iliac vein. The lowest incidence of DVT was seen with the Greenfield and Bird's Nest filters as compared with the smaller Simon Nitinol and VenaTech filters (20% vs 55%; P < .05). The highest incidence of thrombosis occurred in patients with pre-insertion pulmonary emboli (50%; 8 of 16) as compared with those patients with DVT (38%; 6 of 16) and prophylactic insertion (0%; 0 of 3). However, the subgroups were too small to attain statistical significance. CONCLUSION: There is a continuing and significant incidence of new DVT development ipsilateral to the percutaneous femoral insertion site of vena caval filters. The smaller diameter filters are not associated with a lower incidence of femoral thrombosis.

Anticoagulants↗
PubMed1999

Thigh isosulfan blue injection in the treatment of postoperative lymphatic complications.

Postoperative lymphatic complications after infrainguinal revascularization are troublesome and potentially serious complications. Vital dye injection into the web spaces of the foot has been recommended as a simple and reliable method to identify lymphatic channel disruption before groin exploration. Such distal injections, however, are not always successful. We describe a modified technique using a proximal thigh injection with isosulfan blue, which is faster and more useful than the distal web space method.

Embolism, Cholesterol↗
PubMed1999

A national survey of practice patterns in the noninvasive diagnosis of deep venous thrombosis.

PURPOSE: Recent studies have recommended unilateral venous duplex scanning for the diagnosis of deep venous thrombosis (DVT) in patients who are unilaterally symptomatic. Vascular laboratory accreditation standards, however, imply that bilateral leg scanning should be performed. We examined whether actual practice patterns have evolved toward limited unilateral scanning in such patients. METHODS: A questionnaire was mailed to all 808 vascular laboratories in the United States that were accredited by the Intersocietal Commission for the Accreditation of Vascular Laboratories (ICAVL). To encourage candid responses, the questionnaires were numerically coded and confidentiality was assured. RESULTS: A total of 608 questionnaires (75%) were completed and returned. Most of the respondents (442; 73%) were either community-hospital or office-based laboratories, and the remaining 163 (27%) were university or affiliated-hospital laboratories. Most of the laboratories (460; 76%) had been in existence for 9 years or more, and 65% had been ICAVL-accredited in venous studies for 3 years or more. Board-certified vascular surgeons were the medical directors in 54% of the laboratories. Duplex ultrasound scanning was the diagnostic method used by 98% of the laboratories. In patients with unilateral symptoms, 75% of the laboratories did not routinely scan both legs for DVT. A large majority (75%) believe that bilateral scanning is not clinically indicated. Only 57 laboratories (14%) recalled having patients return with a DVT in the previously unscanned leg, with 93% of these laboratories reporting between one and five such patients. This observation correlated with larger volumes of venous studies performed by those laboratories (P <.05). Similarly, only 52 laboratories (12%) recalled having patients return with subsequent pulmonary emboli. Of these laboratories, only five reported proximal DVT in the previously unscanned legs of such patients. Of all these laboratories, therefore, only 1% (5 of 443) have potentially missed the diagnosis of a DVT that caused a preventable pulmonary embolus with such a policy. Among those laboratories that always perform bilateral examinations, 41% do so because of habit. Most (61%) of the laboratories that perform bilateral scanning would do unilateral scanning if it were specifically approved by ICAVL. CONCLUSION: Three quarters of the ICAVL-accredited vascular laboratories perform limited single-extremity scanning for the diagnosis of DVT in patients with unilateral symptoms. This broad clinical experience suggests that this practice is widespread in selected patients. Clinical protocols should be established to provide guidelines for local laboratory implementation.

Health Care Surveys↗
PubMed1997

Automatic postoperative monitoring of infrainguinal bypass procedures.

OBJECTIVE: To evaluate the usefulness of a portable, computer-based, oscillometric, noninvasive blood pressure monitor for the automatic surveillance of postoperative infrainguinal bypasses. DESIGN: Prospective unblinded study. SETTING: Regional tertiary care Veterans Affairs medical center. PATIENTS: A total of 60 limbs were examined in 3 groups (n = 20 in each group): normal, asymptomatic volunteers; older patients with symptomatic peripheral vascular disease; and patients who had undergone infrainguinal bypass procedures. INTERVENTIONS: Noninvasive blood pressure monitor pressures, complete lower extremity arterial studies with Doppler ankle-brachial index (ABI), segmental pressures, and pulse volume recordings were performed in all groups. The patients who had undergone surgery also had hourly noninvasive blood pressure measurements taken. MAIN OUTCOME MEASURES: Ankle-brachial indices obtained with the noninvasive blood pressure monitor were compared with simultaneous manual Doppler ABIs and pulse volume recordings. RESULTS: There was a significant overall correlation between the Doppler-derived ABIs and automatic oscillometric values (r = 0.89, P < .001). Although there was a slight difference in absolute values (+/-SEM) (0.90 +/- 0.03 vs 0.84 +/- 0.03, respectively), an excellent correlation was found between the 2 methods in the clinically relevant range of ABI values between 0.60 and 1.10. The oscillometric method, however, overestimated the ABI when it was less than 0.60 by the Doppler method (0.61 +/- 0.02 vs 0.44 +/- 0.03, P < .001) and underestimated it when it was more than 1.10 (1.05 +/- 0.02 vs 1.16 +/- 0.01, P < .001). (All values given as +/-SEM.) Oscillometric overestimation correlated with depressed pulse volume recording waveforms (P < .001) or diminished pulse volume recording amplitudes of less than 10 mm (P < .001). CONCLUSION: The automatic oscillometric monitor provides a useful, accurate, objective, and quantitative method for postoperative bypass graft surveillance.

Adult↗
PubMed1997

Blunt carotid artery injuries.

BACKGROUND: Blunt carotid artery trauma remains a rare but potentially devastating injury. Early detection and treatment remain the goals of management. Our objective was to identify patients sustaining blunt carotid injuries at a regional trauma center and report on the incidence, demographics, diagnostic workup, management, and outcome. STUDY DESIGN: A retrospective chart review was performed of patients sustaining blunt carotid artery injury between 1990 and 1996. RESULTS: Twenty patients were identified during the 7-year period. All patients suffered blunt trauma, with motor vehicle accidents being the most common mechanism, and the internal carotid the most frequently injured vessel. Associated injuries were present in all patients, with head (65%) or chest (65%) injuries being the most common. The combination of head and chest trauma (45%) was found to be associated with a 14-fold increase in the likelihood of carotid injury. Cerebral angiography was diagnostic in all patients and the majority were treated nonoperatively with anticoagulation. Twenty percent of patients were discharged with a normal neurologic exam, while 45% left with a significant neurologic deficit. Overall mortality was 5%. CONCLUSIONS: Blunt carotid injuries are rare but are associated with significant morbidity and mortality. The combination of craniofacial and chest wounds should raise the index of suspicion for blunt carotid injury. Anticoagulation was associated with the least morbidity.

Adolescent↗
PubMed1996

Decreased nitric oxide production following extremity ischemia and reperfusion.

BACKGROUND: Nitric oxide (NO), the endogenous vasodilator, is an important regulator of vascular tone. We investigated NO production following lower extremity ischemia. METHODS: Rabbits underwent 6 hours of bilateral leg ischemia followed by unrestricted reperfusion. Physiologic parameters were continuously measured and blood was assayed for NO2 and NO3. RESULTS: Acute ischemia of the lower extremities produced an immediate increase in mean arterial blood pressure while later reperfusion induced a significant decrease (P < 0.0005). There was a fall in femoral blood flow during reperfusion. NO2/ NO3 concentrations decreased significantly to 89% of baseline values after ischemia and 77% after 1 hour of reperfusion (P < 0.005). A significantly higher mortality was found in association with decreased NO2/NO3 concentrations. CONCLUSIONS: Nitric oxide appears to be a regulator of regional blood flow during reperfusion following extremity ischemia. Decreased NO production may contribute to impaired regional blood flow and mortality.

Animals↗
PubMed1996

Inappropriate use of venous duplex scans: an analysis of indications and results.

PURPOSE: The increasing demand for venous duplex scans despite the relative rarity of detecting acute deep venous thrombosis (DVT) prompted us to review our experience with this diagnostic method. METHODS: We retrospectively analyzed the results and indications of 2993 lower extremity venous duplex scans performed between July 1, 1992, and June 30, 1994, at our institution. The indication for the study and the results were prospectively recorded in a computerized data bank. The indications for these studies were leg pain (34%), leg swelling (24%), surveillance for DVT in a patient at high risk (23%), searching for a source of pulmonary embolism (14%), follow-up of previously diagnosed DVT (3%), and other indications (i.e., varicose veins, venous ulcer, 2%). RESULTS: Overall, 74.1% of all scans were completely normal, and only 13.1% detected acute proximal (popliteal vein or higher) DVT. Scans performed for surveillance (87.3% normal) or source of pulmonary embolism (79.6% normal) were significantly more likely to be normal than when performed for any other indication (p < 0.01). When leg edema or calf tenderness was present, the incidence of acute DVT was significantly greater for all indications (p < 0.0001). CONCLUSIONS: The high percentage of normal venous scans implies that this diagnostic method is being inappropriately used. In the current climate of cost containment our data suggest that indications for venous duplex scans must be better defined and that improved education for referring physicians is needed.

Acute Disease↗
PubMed1995

Multicenter trial to evaluate vascular magnetic resonance angiography of the lower extremity. American College of Radiology Rapid Technology Assessment Group.

OBJECTIVES: To assess the value of magnetic resonance angiography (MRA) in presurgical evaluation of patients with severe lower limb atherosclerotic occlusive disease and to assess the feasibility of rapidly conducting rigorous technology assessment. DESIGN: Blinded, prospective study of consecutive patients with signs or symptoms of severe infrainguinal peripheral vascular disease who were candidates for percutaneous or surgical intervention. Using both descriptive statistics and multivariate logistic analyses, MRA was compared with contrast arteriography (CA) (the current technique) for imaging 15 arterial segments of the leg and foot. Intraoperative contrast angiography was the "gold" standard. Also studied was the effect of adding MRA to the information used in planning treatment. SETTING: Six US hospitals, one a community hospital. PATIENTS: A total of 155; 84% with either rest pain or tissue loss. RESULTS: Sensitivity in distinguishing patent segments from completely occluded segments was 83% for CA and 85% for MRA; both had 81% specificity. For distinguishing near-normal segments (suitable as bypass graft termini), CA was less sensitive than MRA (77% vs 82%), but more specific (92% vs 84%). After adjusting for same-reader effects, odds of correctly distinguishing patent segments were 1.6 times as great for MRA as for CA (P < .01); for distinguishing near-normal segments, the odds for CA were 1.5 times as great as for MRA (P < .05). The addition of MRA changed the treatment plan in 13% of patients; in 86% of these cases, the surgery actually performed indicated that the MRA-inclusive plan was superior. CONCLUSIONS: Individually, MRA and CA are approximately equivalent in diagnostic accuracy. The addition of MRA to treatment plans based only on CA and other diagnostic information clearly improves the plans. Completed in 15 months (as planned), our study demonstrates the feasibility of conducting rigorous technology assessment rapidly enough to be timely even in fields in which diagnostic and treatment techniques are rapidly changing.

Adult↗
PubMed1995

Surveillance venous scans for deep venous thrombosis in multiple trauma patients.

The high reported incidence of deep venous thrombosis (DVT) in trauma patients has prompted surveillance venous duplex scanning of the lower extremities. We report our retrospective experience with 183 multiple trauma patients who were admitted to the surgical intensive care unit and underwent 261 surveillance venous scans. There were 122 men and 61 women whose average age was 38 years. All patients were treated prophylactically with either extremity pneumatic compression or subcutaneous heparin to prevent DVT. Most (87%) patients suffered blunt trauma and had either head (3%), spinal (3%), intra-abdominal (9%), or lower extremity (17%) injuries or a combination of injuries (68%). Almost two thirds of the patients had no symptoms suggestive of possible DVT. Of the 261 venous scans performed, 239 (92%) were normal, 16 (6%) were positive for proximal lower extremity DVT, and six (2%) showed thrombus limited to the calf veins. Patients with symptoms of lower extremity DVT were significantly more likely to have proximal DVT compared to those without symptoms (15% vs. 5%, p < 0.05). Patients with spinal injuries also had a higher incidence of proximal DVT (18% vs. 6%, p < 0.05). At current hospital charges, the cost to identify each proximal DVT was $6688. If surveillance duplex scans were performed on all trauma patients in the surgical intensive care unit, the national annual expense would be $300,000,000. Routine DVT surveillance is expensive and should be reserved for symptomatic patients or those with spinal injuries.

Adult↗
PubMed1995

Contralateral duplex scanning for deep venous thrombosis is unnecessary in patients with symptoms.

PURPOSE: Bilateral lower extremity venous duplex scanning for acute deep venous thrombosis (DVT) has been advocated because of the high incidence of occult contralateral leg involvement. We investigated the clinical necessity of such a policy. METHODS: The results from 2996 venous duplex studies performed during the past 2 years were retrospectively reviewed. A total of 1694 of these scans were performed on patients with symptoms, of whom 248 (15%) were found to have an acute DVT. Symptoms were limited to one side in 198 patients, whereas bilateral complaints were noted in 50 patients. RESULTS: Among the patients with symptoms of acute DVT, 72 (29%) had bilateral involvement. Bilaterality was more likely in patients with bilateral symptoms than in those with only unilateral symptoms (56% vs 22%; p < 0.005). Of the patients with unilateral symptoms and bilateral DVT, all of them had either acute (80%) or acute and chronic (20%) thrombosis in the symptomatic leg. The contralateral asymptomatic limb had fewer acute and more chronic DVT (41% and 55%, respectively). No patient from the entire group admitted with symptoms had an acute DVT in the asymptomatic limb without a concomitant acute DVT in the symptomatic leg. Unilateral scanning would decrease the examination time by 21% and potentially increase total reimbursement for symptomatic venous scans by 9% compared with routine bilateral duplex scanning. CONCLUSIONS: Although bilateral involvement is frequent in patients with symptoms of acute DVT, treatment in these patients is not altered by this finding. We conclude that contralateral venous scanning in patients with unilateral symptoms is not clinically indicated and that unilateral scanning would result in improved cost-efficiency for vascular laboratories.

Acute Disease↗
PubMed1995

Vascular impingement by external fixator pins: a case report.

Associated vascular injuries after external fixation of the tibia are rarely encountered. We report a case of impingement of the anterior tibial artery after application of an external fixator. The extrinsic compression disappeared after pin removal. Proper technique of pin placement is re-emphasized.

Adult↗
PubMed1994

Preoperative duplex venous mapping: a comparison of positional techniques in patients with and without atherosclerosis.

PURPOSE: Preoperative duplex venous mapping is the preferred modality to measure the diameter of the greater saphenous vein and its suitability as an arterial conduit for infrainguinal bypass. We wanted to determine the optimal mapping technique and maximal venous diameter in patients with and without atherosclerosis. METHODS: Three groups of patients were prospectively studied: younger control subjects (n = 20), preoperative atherosclerotic patients (n = 10), and older control subjects (n = 10). All patients underwent greater saphenous vein duplex mapping in a standardized manner. Maximal internal vein diameters were measured with the subjects in the supine position in bed, in the 20 degree reversed Trendelenburg position, sitting on the edge of the bed, standing, and in the supine position with a high-thigh, low-pressure tourniquet. Measurements were taken just beyond the saphenofemoral junction, in the distal thigh, below the knee, at midcalf, and superior to the medial malleolus. RESULTS: In younger control subjects an increasingly more erect position resulted in progressively larger measured vein diameters at all levels along the length of the leg. Both patients with atherosclerosis and older control subjects had no such increase in venous diameter with any positional change from the supine position to standing. Patients with atherosclerosis also had significantly smaller measured veins than either younger or older control subjects. A high-thigh tourniquet significantly increased vein diameters in the atherosclerotic group to the size of vein diameters in the older control group, although the absolute size differences were not large. CONCLUSIONS: The optimal position for venous mapping is with the patient in a supine position. If the internal vein diameter is below an acceptable minimum size, a high-thigh tourniquet will maximally distend the vein in patients with atherosclerosis. Vein diameter decreases with age and is less distended in patients with atherosclerosis compared with older patients without atherosclerosis.

Adult↗