Regional Angiogenesis With Vascular Endothelial Growth Factor in Peripheral Arterial Disease

Background— “Therapeutic angiogenesis” seeks to improve perfusion by the growth of new blood vessels. The Regional Angiogenesis with Vascular Endothelial growth factor (RAVE) trial is the first major randomized study of adenoviral vascular endothelial growth factor (VEGF) gene transfer for the treatment of peripheral artery disease (PAD).

Methods and Results— This phase 2, double-blind, placebo-controlled study was designed to test the efficacy and safety of intramuscular delivery of AdVEGF121, a replication-deficient adenovirus encoding the 121-amino-acid isoform of vascular endothelial growth factor, to the lower extremities of subjects with unilateral PAD. In all, 105 subjects with unilateral exercise-limiting intermittent claudication during 2 qualifying treadmill tests, with peak walking time (PWT) between 1 to 10 minutes, were stratified on the basis of diabetic status and randomized to low-dose (4×10 9 PU) AdVEGF121, high-dose (4×10 10 PU) AdVEGF121, or placebo, administered as 20 intramuscular injections to the index leg in a single session. The primary efficacy end point, change in PWT (ΔPWT) at 12 weeks, did not differ between the placebo (1.8±3.2 minutes), low-dose (1.6±1.9 minutes), and high-dose (1.5±3.1 minutes) groups. Secondary measures, including ΔPWT, ankle-brachial index, claudication onset time, and quality-of-life measures (SF-36 and Walking Impairment Questionnaire), were also similar among groups at 12 and 26 weeks. AdVEGF121 administration was associated with increased peripheral edema.

Conclusions— A single unilateral intramuscular administration of AdVEGF121 was not associated with improved exercise performance or quality of life in this study. This study does not support local delivery of single-dose VEGF 121 as a treatment strategy in patients with unilateral PAD.

The 2020 update of the CEAP classification system and reporting standards

The CEAP (Clinical-Etiology-Anatomy-Pathophysiology) classification is an internationally accepted standard for describing patients with chronic venous disorders and it has been used for reporting clinical research findings in scientific journals. Developed in 1993, updated in 1996, and revised in 2004, CEAP is a classification system based on clinical manifestations of chronic venous disorders, on current understanding of the etiology, the involved anatomy, and the underlying venous pathology. As the evidence related to these aspects of venous disorders, and specifically of chronic venous diseases (CVD, C2-C6) continue to develop, the CEAP classification needs periodic analysis and revisions. In May of 2017, the American Venous Forum created a CEAP Task Force and charged it to critically analyze the current classification system and recommend revisions, where needed. Guided by four basic principles (preservation of the reproducibility of CEAP, compatibility with prior versions, evidence-based, and practical for clinical use), the Task Force has adopted the revised Delphi process and made several changes. These changes include adding Corona phlebectatica as the C4c clinical subclass, introducing the modifier "r" for recurrent varicose veins and recurrent venous ulcers, and replacing numeric descriptions of the venous segments by their common abbreviations. This report describes all these revisions and the rationale for making these changes.

Rupture rate of large abdominal aortic aneurysms in patients refusing or unfit for elective repair

CONTEXT

Among patients with abdominal aortic aneurysm (AAA) who have high operative risk, repair is usually deferred until the AAA reaches a diameter at which rupture risk is thought to outweigh operative risk, but few data exist on rupture risk of large AAA.

OBJECTIVE

To determine the incidence of rupture in patients with large AAA.

DESIGN AND SETTING

Prospective cohort study in 47 Veterans Affairs medical centers.

PATIENTS

Veterans (n = 198) with AAA of at least 5.5 cm for whom elective AAA repair was not planned because of medical contraindication or patient refusal. Patients were enrolled between April 1995 and April 2000 and followed up through July 2000 (mean, 1.52 years).

MAIN OUTCOME MEASURE

Incidence of AAA rupture by strata of initial and attained diameter.

RESULTS

Outcome ascertainment was complete for all patients. There were 112 deaths (57%) and the autopsy rate was 46%. Forty-five patients had probable AAA rupture. The 1-year incidence of probable rupture by initial AAA diameter was 9.4% for AAA of 5.5 to 5.9 cm, 10.2% for AAA of 6.0 to 6.9 cm (19.1% for the subgroup of 6.5-6.9 cm), and 32.5% for AAA of 7.0 cm or more. Much of the increased risk of rupture associated with initial AAA diameters of 6.5-7.9 cm was related to the likelihood that the AAA diameter would reach 8.0 cm during follow-up, after which 25.7% ruptured within 6 months.

CONCLUSION

The rupture rate is substantial in high-operative-risk patients with AAA of at least 5.5 cm in diameter and increases with larger diameter.

Regional Angiogenesis with Vascular Endothelial Growth Factor (VEGF) in peripheral arterial disease: Design of the RAVE trial

BACKGROUND

Patients with intermittent claudication caused by infrainguinal atherosclerosis have limited pharmacologic options "Therapeutic angiogenesis" is a novel treatment approach that seeks to improve perfusion of ischemic limbs by the induction of collateral vessel formation. This trial is a phase 2 randomized double-blind placebo-controlled proof of concept trial that will use an intramuscular adenoviral gene transfer approach of vascular endothelial growth factor, 121 isoform (Ad(GV)VEGF(121.10)) to patients with severe IC caused by infrainguinal disease.

METHODS

This is a phase 2, double-blind, randomized, placebo-controlled, dose-finding, multicenter study. Patients with severe intermittent claudication caused by infrainguinal atherosclerosis predominantly involving the superficial femoral artery confirmed with imaging studies that meet inclusion criteria will be stratified on the basis of the presence or absence of diabetes mellitus and randomized in a 1:1:1 fashion to low dose (4 x 10(9) particle units), high dose (4 x 10(10) particle units), or placebo arms (35-36 patients per group). Subjects are required to have exercise-limiting IC in the index extremity during 2 qualifying exercise treadmill tests, with peak walking times between 1 and 10 minutes. A single dose of Ad(GV)VEGF(121.10) will be administered as 20 intramuscular injections throughout the area of the lower limb requiring collateralization.

RESULTS

The primary efficacy parameter for the Regional Angiogenesis With Vascular Endothelial Growth Factor (RAVE) trial is the change in peak walking time at 12 weeks compared with baseline. The sample size is expected to provide an 80% power to detect a difference of 1.5 minutes between any of the 2 treatment groups and the placebo group. Secondary efficacy parameters include claudication onset time, hemodynamic effects of therapy assessed with ankle-brachial index, assessment of physical impairment, and health-related quality of life as measured with the Walking Impairment Questionnaire and SF-36 Health Survey. All randomized patients will also be evaluated for safety.

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.

Aortoiliac Occlusive Disease in Patients with Known or Suspected Peripheral Vascular Disease: Safety and Efficacy of Gadofosveset-enhanced MR Angiography—Multicenter Comparative Phase III Study

PURPOSE

To prospectively determine the safety and efficacy of the gadolinium-based blood pool magnetic resonance (MR) imaging contrast agent gadofosveset in patients known to have or suspected of having peripheral vascular disease.

MATERIALS AND METHODS

Ethical committee approval and patient written informed consent were obtained. This study was compliant with the Health Insurance Portability and Accountability Act. Adults known or suspected to have peripheral vascular disease received gadofosveset (0.03 mmol per kilogram of body weight) for MR angiography of the aortoiliac region. Gadofosveset-enhanced MR angiography and unenhanced two-dimensional time-of-flight MR angiography were compared with the reference standard, conventional angiography, for the presence of vascular stenosis. All patients were monitored for adverse events with hematologic analysis, analysis of blood chemistry, urinalysis, and electrocardiographic parameters; these methods were analyzed to determine safety.

RESULTS

A total of 274 patients were enrolled at 37 centers. Gadofosveset-enhanced MR angiography showed significant improvement (P < .001) compared with unenhanced MR angiography for each of the readers for diagnosis of clinically significant (> or = 50%) stenosis. Specificity and accuracy were significantly greater for three readers, and sensitivity increased significantly for two readers. For all readers, the area under the receiver operator characteristic curve for both quantitative and qualitative measures of significant disease increased (P < .001) for gadofosveset-enhanced MR angiography versus two-dimensional time-of-flight MR angiography. All readers also expressed more confidence in diagnosis (P < .001) and found fewer images to be uninterpretable (0.5% vs 11.0%). The most common adverse events were as follows: feeling hot, 12 (4.4%) patients; nausea, 10 (3.6%) patients; headache, nine (3.3%) patients; and burning sensation, eight (2.9%) patients. Only four serious adverse events were reported, in three patients, and all events were rated as unlikely related to the drug. No patients were excluded because of adverse events or laboratory abnormalities. There were no clinically important trends in the findings of hematologic analysis, blood chemistry, urinalysis, electrocardiography, or physical examination.

CONCLUSION

On the basis of substantial improvements over non-contrast MR angiography in efficacy and a minimal and transient side-effect profile, gadofosveset was found to be safe and effective for MR angiography in patients known or suspected to have peripheral vascular disease.

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.

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.

Recognition and management of major vessel injury during laparoscopy

Laparoscopy is one of the most commonly performed procedures in the United States. Injury to a major retroperitoneal vessel occurs in 0.3% to 1.0% of procedures, most commonly during laparoscopic entry while placing the Veress needle or primary trocar. Fatal outcome can be related to massive gas embolism or exsanguination. Recommended treatment for gas embolism can range from supportive measures to external chest compression and insertion of a central line to withdraw gas from the right side of the heart. Recommended treatment of major vessel injury with massive hemorrhage consists of rapid laparotomy and control of hemorrhage using direct pressure until a surgeon experienced in vascular procedures arrives. When a major vessel injury occurs in a surgical facility distant from a medical center and without an available surgeon with vascular experience, based on the trauma literature, we recommend temporary control of blood loss using abdominal packing and closure (i.e., "damage control surgery") and judicious resuscitation (i.e., "damage control resuscitation") before transportation to a medical center.

Quantitative histochemical evaluation of skeletal muscle ischemia and reperfusion injury

Acute arterial obstruction to the extremities is associated with significant morbidity and mortality. The evaluation of accompanying skeletal muscle injury has thus far been indirect and imprecise. Triphenyltetrazolium chloride (TTC) is an oxidation-reduction indicator which allows for the histochemical quantitation of skeletal muscle injury. In 21 anesthetized nonheparinized adult mongrel dogs, the isolated in vivo gracilis muscle underwent 4, 6, or 8 hr of ischemia with and without reperfusion. The muscles were excised and cut into 1-cm segments, representative muscle biopsies for electron microscopy were taken, each segment was stained in 1% TTC, and the total area of staining was measured with computerized planimetry. All control muscles stained completely with a dark red color. After 4, 6, or 8 hr of ischemia, quantitative measurements of muscle staining indicative of normal tissue were present in 98 +/- 1%, 59 +/- 5%, and 23 +/- 9% of the total muscle areas, respectively. Six hours of ischemia followed by reperfusion was associated with only 36 +/- 9% of the muscle being stained. Segmental TTC staining demonstrated that reperfusion was associated with greater injury, and less TTC staining, in the proximal portion of the gracilis muscle at the site of entry of the major arterial pedicle. The distal muscle did not demonstrate increased damage with reperfusion. It is hypothesized that protection of the distal muscle from reperfusion injury may be due to an absence of reflow farther away from the artery.

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.

Improvement in the visualization of superficial arm veins being evaluated for access and bypass

OBJECTIVES

Duplex ultrasound mapping of arm veins is being performed with increasing frequency. Unlike ultrasound testing in other areas, this has never been subjected to a gold standard invasive test to determine accuracy. Duplex mapping appears to have a good predictive value whenever large veins are demonstrated preoperatively, but its ability to accurately measure minimum-sized veins is unproven. In this study, we compared diameter measurements obtained under six different conditions and used the maximum diameter as the comparison gold standard.

METHODS

A 12-MHz linear probe was used to measure the cephalic and basilic vein cross-sectional diameters at the wrist level in 24 normal volunteers under the following conditions: (1) resting supine with a room temperature of 23 degrees to 24 degrees C, (2) supine with a tourniquet inflated to 65 mm Hg, (3) sitting with the arm dangling, (4) sitting with a tourniquet, (5) sitting after a 2-minute immersion in warm water (44 degrees C), and (6) same with tourniquet. Half the subjects underwent the protocol in a different order.

RESULTS

Vein diameters were significantly larger after submersion in warm water compared with supine (P < .05, pair-wise multiple comparison procedure, Student-Newman-Keuls method). Assuming the sitting position (from supine) resulted in a decreased arm vein diameter 58% of the time. In 25% of the normal subjects, the cephalic vein size was <2 mm, which increased to >2 mm after warming. All subjects had either a cephalic or a basilic vein at the wrist that was >3.1 mm after warming.

CONCLUSION

Use of warm water immersion before vein diameter measurement in a sitting position, without a tourniquet, will result in significantly larger diameter findings in normal arm veins. These diameters are likely to more closely resemble the venous diameter after distension with arterial pressure. Further studies are needed to see if warming in patients could result in increased utilization of autogenous arm vein for dialysis access and bypass.

Iloprost attenuates the increased permeability in skeletal muscle after ischemia and reperfusion

Increased vascular permeability is an early and sensitive indicator of ischemic muscle injury, occurring before significant histologic or radionuclide changes are evident. We investigated the effect of iloprost, a stable prostacyclin analog, on microvascular permeability in a rat striated muscle model. In six control and six experimental animals the cremaster muscle was dissected, placed in a closed-flow acrylic chamber, and suffused with a bicarbonate buffer solution. Dextran labeled with fluorescein was injected intravenously as a macromolecular tracer, and microvascular permeability was determined on the basis of clearance of the fluorescent tracer. Two hours of ischemia were followed by 2 hours of reperfusion. In the experimental group iloprost (0.5 microgram/kg/min) was given in a continuous intravenous infusion. Microvascular permeability increased significantly during reperfusion in both control and experimental animals (p less than 0.0001). Treatment with iloprost, however, significantly attenuated this response compared to the control group, 4.8 +/- 0.3 versus 7.3 +/- 0.5 microliters/gm/min, respectively (p less than 0.0001). Iloprost decreases the rise in vascular permeability after ischemia and reperfusion. Experimental clinical use of iloprost under controlled conditions in the treatment of patients with acute skeletal muscle ischemia appears justified.

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.

A phase I trial of alfimeprase for peripheral arterial thrombolysis

PURPOSE

To evaluate the safety profile, pharmacokinetics, and thrombolytic activity of alfimeprase, a novel direct-acting thrombolytic agent, in patients with chronic peripheral arterial occlusion (PAO).

MATERIALS AND METHODS

In this multicenter, open-label, single-dose, dose-escalation study, 20 patients with worsening symptoms of lower extremity ischemia within 6 months of enrollment were treated with alfimeprase in five escalating dose cohorts (0.025 mg/kg, 0.05 mg/kg, 0.1 mg/kg, 0.3 mg/kg, and 0.5 mg/kg) by means of intraarterial and sometimes intrathrombic pulsed infusion. The primary endpoint was safety assessed by adverse event rates. Additional safety assessments included vital sign monitoring, serum chemistry testing, hematologic testing, and coagulation testing for 28 days after the procedure, as well as alpha2-macroglobulin and antialfimeprase antibody testing for as long as 3 months after treatment. Pharmacokinetic parameters were evaluated with use of an assay that measures free and alpha2-macroglobulin-bound (ie, total) alfimeprase.

RESULTS

No patient experienced a hemorrhagic adverse event. Mean plasminogen and fibrinogen concentrations were not substantially altered by treatment. Three transient treatment-related adverse events were reported in the same patient: one incidence each of increased blood fibrinogen level, skin rash, and headache. All three adverse events were graded as mild. The pharmacokinetic profile of alfimeprase suggested that the half-life for total alfimeprase ranges from 11 to 54 minutes (median, 25 min) in patients with PAO. The serum alpha2-macroglobulin concentrations decreased transiently in a dose response-like manner between 12 and 24 hours and returned to within normal limits approximately 14 days after alfimeprase exposure.

CONCLUSIONS

Alfimeprase in doses as high as 0.5 mg/kg was generally well-tolerated in patients with chronic PAO. No bleeding complications were noted. The stable fibrinogen concentrations suggest that the activity of alfimeprase may be limited to the target thrombus. Alfimeprase holds the potential to achieve dissolution of thrombus with a diminished risk of hemorrhage.

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.

Clinical gene therapy for nonmalignant disease

Gene therapy is envisioned as a potentially definitive treatment for a variety of diseases that have a genetic etiology. We reviewed trials of clinical gene therapy for nonmalignant, single-gene, and multifactorial disorders and infectious diseases, and found limited evidence suggesting that gene therapy may benefit patients who have severe, combined, immunodeficiency disorder; cystic fibrosis; coronary artery disease or peripheral arterial disease; or hemophilia. Effective gene therapy requires the targeted transfer of exogenous genetic material into human cells and the subsequent regulated expression of the corresponding gene product. Because no phase 3 randomized controlled trials have been completed that fulfill these criteria, it is difficult to correlate signs of clinical benefit with the administration of gene therapy in any disease. Additional clinical and basic research is needed to determine the future role of gene therapy.

Differential effects of vascular growth factors on arterial and venous angiogenesis

OBJECTIVE

Angiogenesis, the development of new blood vessels, has become an area of increased interest for both scientific and clinical application purposes. Proangiogenic agents, such as vascular endothelial growth factor (VEGF) and naltrexone, have been shown to effectively induce new blood vessel growth. Other growth factors, such as the endogenous opioid growth factor (OGF; [Met(5)]-enkephalin) and retinoic acid, are inhibitors of angiogenesis. The differential effects on veins and arteries, however, by any vascular growth factor, have not previously been investigated.

METHODS

The chick chorioallantoic membrane (CAM) assay was used for the in vivo quantitation of angiogenesis. After 3 days of incubation, fertilized chick embryos were explanted, and a 3.2-mm methylcellulose disk containing either the known angiogenic stimulators VEGF (0.2 microg, 1.0 microg) or naltrexone (0.1 microg, 5.0 microg), or the angiogenic inhibitors OGF (1.0 microg, 5.0 microg) or retinoic acid (1.0 microg) was placed onto the CAM surface. An equal volume of distilled water served as a control. After 2 days of growth, the CAM arteries and veins were identified, and images were obtained with a digital camera. Quantitative analysis of angiogenesis was performed on a 100-mm(2) area surrounding the applied disk, and the number and length of the veins and arteries were measured.

RESULTS

The angiogenic stimulators VEGF and naltrexone markedly increased both the total number and length of all blood vessels as compared with control values. The mean length of blood vessels decreased, suggesting the induction of new vessel growth. VEGF and naltrexone proportionately increased vein and arterial angiogenesis, maintaining artery/vein ratios for vessel number and length that were unchanged compared with controls. The angiogenic inhibitors, OGF and retinoic acid, notably decreased the total number and length of blood vessels in the CAM preparations. However, these compounds had a disproportionately greater inhibitory effect on arterial angiogenesis as reflected in decreased artery/vein ratios for vessel number and length.

CONCLUSIONS

The angiogenic stimulators VEGF and naltrexone induce development of veins and arteries in a proportional manner. In contrast, the angiogenic inhibitors OGF and retinoic acid demonstrated a greater inhibitory effect on arterial as compared with venous angiogenesis. Such differential effects on angiogenesis may be important in both defining mechanisms of action and designing therapeutic interventions.

Factors influencing resilience and burnout among resident physicians - a National Survey

BACKGROUND

Residency training exposes young physicians to a challenging and high-stress environment, making them vulnerable to burnout. Burnout syndrome not only compromises the health and wellness of resident physicians but has also been linked to prescription errors, reduction in the quality of medical care, and decreased professionalism. This study explored burnout and factors influencing resilience among U.S. resident physicians.

METHODS

A cross-sectional study was conducted through an online survey, which was distributed to all accredited residency programs by Accreditation Council of Graduate Medical Education (ACGME). The survey included the Connor-Davidson Resilience Scale (CD-RISC 25), Abbreviated Maslach Burnout Inventory, and socio-demographic characteristics questions. The association between burnout, resilience, and socio-demographic characteristics were examined.

RESULTS

The 682 respondents had a mean CD-RISC score of 72.41 (Standard Deviation = 12.1), which was equivalent to the bottom 25th percentile of the general population. Males and upper-level trainees were more resilient than females and junior residents. No significant differences in resilience were found associated with age, race, marital status, or training program type. Resilience positively correlated with personal achievement, family, and institutional support (p <  0.001) and negatively associated with emotional exhaustion and depersonalization (p <   0.001).

CONCLUSIONS

High resilience, family, and institutional support were associated with a lower risk of burnout, supporting the need for developing a resilience training program to promote a lifetime of mental wellness for future physicians.

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.

Specialty differences in resident resilience and burnout - A national survey

BACKGROUND

Burnout is widespread among resident physicians, but higher resilience is associated with lower burnout. This study characterizes the relationship between resilience and burnout in medical (MR) and surgical (SR) resident physicians.

METHODS

A cross-sectional survey was distributed to all ACGME-accredited residency programs with the Connor-Davidson Resilience Scale and Abbreviated Maslach Burnout Inventory.

RESULTS

Of the 682 respondents, both Medical and Surgical Residents with higher resilience had lower burnout. Higher resilience was seen in Surgical Residents who were men, had greater family support, more residency program support, and enjoyed greater autonomy. Burnout was greater in women, Caucasians, those in an academic setting, and with less autonomy and program support. Burnout was similar among the medical and surgical groups, but surgical trainees had higher resilience. Overall, family and institutional support was associated positively with high resilience and decreased burnout.

CONCLUSIONS

Increasing resilience and program support can decrease burnout, especially for high-risk subgroups.

Contrast enhanced duplex ultrasound imaging of the mesenteric arteries

Duplex ultrasound of the visceral arteries is a technically challenging procedure. We examined the clinical usefulness of perflutren intravenous ultrasound contrast to improve the diagnostic accuracy of such studies. Seventeen patients were prospectively studied. A color duplex imaging study of the visceral vasculature was performed with and without the contrast agent. Vessels were imaged and peak systolic velocity and Doppler waveforms of the aorta, celiac artery, superior mesenteric artery, and the inferior mesenteric artery were examined. These results were independently compared to those of contrast angiography. From this analysis we concluded contrast-enhanced duplex imaging of the mesenteric arteries is safe but not routinely required when performed by an experienced sonographer. Ultrasound contrast may be helpful in difficult patients when the vessels are not initially successfully visualized.

Prevention of vascular access hand ischemia using the axillary artery as inflow

BACKGROUND

Avoiding dialysis access-associated ischemic steal syndrome (DASS) in patients with upper extremity peripheral vascular occlusive disease while creating a functional hemodialysis vascular access may be challenging. We constructed an autogenous access with primary proximalization of the arterial inflow to prevent hand ischemia in patients at high risk for this complication.

METHODS

Patients requiring hemodialysis access with physical findings suggesting a high risk of access-related hand ischemia (absent radial, ulnar, and brachial palpable pulses associated with small calcified vessels by ultrasound examination) underwent a primary arteriovenous fistula transposition procedure utilizing the axillary artery for inflow. The arteriovenous fistula was either a reversed flow basilic vein transposition supplemented by valvulotomy (n = 22); a translocated reversed basilic vein (n = 4); a cephalic vein harvested into the forearm and placed in a loop configuration for axillary artery inflow (n = 3); or a translocated reversed saphenous vein (n = 1).

RESULTS

Thirty patients with a mean age of 60 years (range, 31-83 years) underwent successful primary axillary artery inflow procedures during a 3-year period. Of these, 23 (77%) were female and 25 (83%) were diabetic. Twenty-one (70%) had previous vascular access procedures and 10 (33%) were obese. No patient developed postoperative ischemia. Three individuals died 2, 14, and 19 months following surgery, none related to vascular access. Three accesses failed after 1, 5, and 7 months and could not be salvaged. Life-table primary, primary assisted, and cumulative patency rates were 57%, 78%, and 87% respectively at 1 year with a mean follow-up of 7 months (range, 1-25 months). Cephalic vein outflow was associated with fewer access failures, fewer interventions postoperatively, and lower rates of arm swelling (P < .01).

CONCLUSIONS

Creating a basilic vein transposition for vascular access utilizing axillary artery inflow is a good option for patients with severe peripheral vascular disease. It offers a high patency rate and the prevention of DASS. Retrograde basilic vein outflow through the median cubital and cephalic vein is associated with the best outcome and is the recommended configuration.

Intestinal ischemia secondary to thromboangiitis obliterans

A 38-year-old woman presented with a 10-month history of postprandial abdominal pain and weight loss. She smoked two packs of cigarettes a day, but her history did not indicate diabetes mellitus, hyperlipidemia, or hypercoagulability. A lateral aortogram documented complete occlusion of all three mesenteric arteries but showed no evidence of atherosclerosis, arteritis, or medial fibroplasia. Two retrograde aortomesenteric grafts, one to the superior mesenteric artery and another to the meandering mesenteric artery, utilizing the greater saphenous vein were placed. Pathologic examination of the inferior mesenteric artery demonstrated changes that were considered diagnostic of thromboangiitis obliterans. We found only 10 confirmed cases of thromboangiitis obliterans involving the mesenteric vessels in the English language literature. The present case appears to be the first involving a woman and the only one in which the main trunk of all three mesenteric vessels was involved.