Long-term intermittent compression increases arteriographic collaterals in a rabbit model of femoral artery occlusion.

OBJECTIVES: To assess the effects of intermittent limb compression on arterial collateral formation in a rabbit-model. DESIGN: Animal study. MATERIAL AND METHODS: New Zealand rabbits (n=11), aged 2-years, weight of at least 4.0 kg, underwent bilateral superficial femoral artery ligation. In ten of these, the experimental leg underwent 60 minutes of daily intermittent compression for a ten week period with 3 sec/90 mmHg pressure inflation and a cycle of 3 times per minute. The contra-lateral limbs were not treated. At the end of the ten-week period, high-resolution angiograms were obtained by barium infusion into the aorta. The angiograms were analyzed in a blinded manner and the number of collateral arteries larger than 100 microns, was counted. Following perfusion-fixation, histological specimens of transverse sections of the compressed semi-membranous muscle were examined. RESULTS: The compressed limbs demonstrated a significantly (8.1+/-.87 vs 6.0+/-.97; p<0.005) greater number of collateral vessels, ranging in size from 100-700 microns, as compared to the control sides. The mean size of collaterals in the compressed limbs was not significantly different (0.33+/-0.17 vs 0.31+/-0.16). Microscopic examination of the collaterals confirmed remodeling by a typical neo-intima consisting of 6-7 cell-layers. CONCLUSIONS: Intermittent limb compression increases the number of angiographical collateral arteries.

CT angiography: in vitro comparison of five reconstruction methods.

OBJECTIVE: Five image reconstruction techniques have been used with CT angiography: axial (cross-sectional), maximum intensity projection (MIP), curved multiplanar reconstruction (MPR), shaded-surface display, and volume rendering. This study used a phantom to compare the accuracy of these techniques for measuring stenosis. SUBJECTS AND METHODS: A 19-vessel phantom containing various grades of concentric stenoses (0-100%) and three lengths (5, 7.5, and 10 mm) of stenoses was used for this study. Scans were obtained with a slice thickness of 2.0 mm, slice interval of 1.0 mm, pitch of 1.0, 120 kVp, 200 mA, and with the vessels oriented parallel to the z-axis and opacified with nonionic contrast material. CT angiography images were produced using five optimized techniques: axial, MIP, MPR, shaded-surface display, and volume rendering; and measurements were made with an electronic cursor in the normal lumen and mid stenosis by five separate investigators who were unaware of vessel and stenosis diameters. Each of the techniques was first optimized according to the radiology literature and our own preliminary testing. RESULTS: For vessels greater than 4 mm in diameter, axial, MIP, MPR, shaded-surface display, and volume-rendering CT angiography techniques all had a measurement error of less than 2.5%. However, axial, MIP, MPR, and shaded-surface display techniques were less accurate in estimating smaller (

Knee in early juvenile rheumatoid arthritis: MR imaging findings.

PURPOSE: To determine the magnetic resonance (MR) imaging findings in the knee in early juvenile rheumatoid arthritis. MATERIALS AND METHODS: MR imaging (1.5 T) was performed in the more symptomatic knee in 30 children with juvenile rheumatoid arthritis with a symptom duration 1 year or less. Conventional, fast spin-echo, three-dimensional gradient-echo, and gadolinium-enhanced T1-weighted images were assessed. Two radiologists independently read the images, and a third resolved disagreements. These images were compared with knee radiographs in 27 children. RESULTS: Mean maximal synovial thickness was 4.8 mm +/- 2.4 (SD). Mean synovial volume was 15.4 mL +/- 10.8. Suprapatellar joint effusions were seen in 26 (87%) of 30 knees, meniscal hypoplasia in 11 (37%) of 30 knees, and abnormal epiphyseal marrow in eight (27%) of 30 knees. Three knees had articular cartilage contour irregularity, fissures, and/or thinning. One knee had a bone erosion. Knee radiographs showed suprapatellar fullness in 78% of the knees, joint space narrowing in one knee, and no bone abnormalities. CONCLUSION: Synovial hypertrophy and joint effusions are the most frequent MR imaging findings of knees in early juvenile rheumatoid arthritis. Early in the disease, radiographically occult cartilage and bone erosions are uncommonly seen at MR imaging. The potential relationship of synovitis to cartilage abnormalities deserves further study.

Comparative assessment of CT and sonographic techniques for appendiceal imaging.

OBJECTIVE: We performed a comparative assessment of CT and sonographic techniques used to assess appendicitis. MATERIALS AND METHODS: One hundred patients with clinically suspected acute appendicitis were examined with sonography, unenhanced focused appendiceal CT, complete abdominopelvic CT using IV contrast material, focused appendiceal CT with colonic contrast material, and repeated sonography with colonic contrast material. Each sonogram was videotaped for subsequent interpretation by three radiologists and two sonographers. The mean sensitivity, specificity, positive and negative predictive values, inter- and intraobserver variability, and diagnostic confidence scores of all observers were used for comparative performance assessments. The three CT examinations were filmed and interpreted separately by four radiologists. Patient discomfort was assessed on a 10-point scale for each radiologic study. Diagnoses were confirmed by pathologic evaluation of resected appendixes or clinical follow-up for a minimum of 3 months after presentation. RESULTS: Twenty-four of the 100 patients had positive findings for acute appendicitis. Both sonographic techniques had high specificity (85-89%) and comparable accuracy (73-75%) but low sensitivity (33-35%) and inter- and intraobserver variability (kappa = 0.15-0.20 and 0.39-0.42, respectively). Unenhanced focused appendiceal CT, abdominopelvic CT, and focused appendiceal CT with colonic contrast material all significantly outperformed sonography (p <0.0001), with sensitivities of 78%, 72%, and 80%; specificities of 86%, 91%, and 87%; and accuracies of 84%, 87%, and 85%, respectively. Abdominopelvic CT gave the greatest confidence in cases with negative findings (p = 0.001), and focused appendiceal CT with colonic contrast material gave the greatest confidence for cases with positive findings (p = 0.02). In terms of inter- and intraobserver variability, focused appendiceal CT with colonic contrast material yielded the highest, and unenhanced focused appendiceal CT the lowest, agreement (interobserver kappa = 0.45 vs. 0.36 and intraobserver kappa = 0.85 vs. 0.76, respectively) (p <0.05). Colonic contrast material was unsuccessfully advanced into the cecum in 18% of patients and leaked in another 24%. Patient discomfort was greatest with focused appendiceal CT using colonic contrast material and least with unenhanced focused appendiceal CT (p <0.05). CONCLUSION: A standard abdominopelvic CT scan is recommended as the initial examination for appendicitis in adult patients. However, focused appendiceal CT with colonic contrast material material should be used as a problem-solving technique in difficult cases.

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.

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.

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.

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.

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.

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.

Fibrolipoma of the median nerve: MRI.

The MRI findings of two patients with fibrolipoma of median nerve are presented. A characteristic 'cable-like' appearance of the tumour was present on T1-weighted images. Unique imaging features of these cases included extension of the lesion into the radial digital nerve of the index finger in case 1 and extraneuronal extension of a exophytic fatty mass from the median nerve into the thenar eminence in case 2.

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.

Magnetic resonance imaging in juvenile rheumatoid arthritis.

OBJECTIVES: This study was undertaken to examine the role of magnetic resonance imaging (MRI) in the management of patients with juvenile rheumatoid arthritis (JRA). METHODS: A Medline search was performed to identify all publications pertaining to MRI in JRA. Further searches and identification of articles from bibliographies identified articles pertaining to plain radiograph imaging in JRA and MRI in adult rheumatoid arthritis. RESULTS: Studies in both children and adults have shown superiority of MRI to plain radiography in detecting synovial hypertrophy and articular cartilage abnormalities. Several studies in adults have shown a good correlation of MR images with gross anatomic as well as histological findings at arthroscopy. Biochemical changes that occur before structural changes within the joint may even be detectable with magnetic resonance spectroscopy. CONCLUSIONS: MRI holds promise for the assessment of disease progression in JRA and may be useful in serial evaluation, as in clinical trials.

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.

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.