Comparison of perioperative costs with fast-track vs standard endovascular aneurysm repair

Background

Perioperative health care utilization and costs in patients undergoing elective fast-track vs standard endovascular aneurysm repair (EVAR) remain unclear.

Methods

The fast-track EVAR group included patients treated with a 14 Fr stent graft, bilateral percutaneous access, no general anesthesia or intensive care monitoring, and next-day hospital discharge. The standard EVAR group was identified from Medicare administrative claims using a matching algorithm to adjust for imbalances in patient characteristics. Hospital outcomes included operating room time, intensive care monitoring, hospital stay, secondary interventions, and major adverse events (MAEs). Perioperative outcomes occurring from hospital discharge to 30 days postdischarge included MAE, secondary interventions, and unrelated readmissions.

Results

Among 1000 matched patients (250 fast-track; 750 standard), hospital outcomes favored the fast-track EVAR group, including shorter operating room time (2.30 vs 2.83 hrs, P<0.001), shorter hospital stay (1.16 vs 1.69 d, P<0.001), less need for intensive care monitoring (4.4% vs 48.0%, P<0.001), and lower secondary intervention rate (0% vs 2.4%, P=0.01). Postdischarge outcomes also favored fast-track EVAR with a lower rate of MAE (0% vs 7.2%, P<0.001) and all-cause readmission (1.6% vs 6.8%, P=0.001). The total cost to the health care system during the perioperative period was $26,730 with fast-track EVAR vs $30,730 with standard EVAR. Total perioperative health care costs were $4000 (95% CI: $3130–$4830) lower with fast-track EVAR vs standard EVAR, with $2980 in savings to hospitals and $1030 savings to health care payers.

Conclusion

A fast-track EVAR protocol using a 14 Fr stent graft resulted in shorter procedure time, lower intensive care utilization, faster discharge, lower incidence of MAE, lower readmission rates, and lower perioperative costs compared to standard EVAR.

Pediatric Vascular Surgical Practice Patterns

BACKGROUND

Vascular surgeons infrequently care for pediatric patients. As such, variability in operative management and available hospital resources at free-standing children's hospitals (CHs) may exist. The study aims were (1) to determine vascular surgeon comfort level with pediatric vascular surgery and (2) to determine variations in pediatric vascular surgery practice patterns.

METHODS

A survey composed of clinical vignettes emailed to all members of Vascular and Endovascular Surgery Society was designed to assess operative management of pediatric vascular conditions and hospital resources. Comparisons of surgeon satisfaction between free-standing CHs and a CH within an adult general hospital were made using Wilcoxon rank-sum tests. Comparison of surgeon comfort between hospital types was made using a McNemar's test. P-values less than or equal to 0.05 indicated statistical significance.

RESULTS

Response rate was 18% (93/525) with 96% (89/93) indicating completion of a 2 year vascular fellowship. Surgeon satisfaction with operative equipment (P = 0.002), support staff (P < 0.001), and vascular laboratory availability (P = 0.01) was significantly lower at CHs. Eighty-seven percent of surgeons operated on fewer than 2 children over the preceding 3 months. For the different clinical vignettes, there was a wide variation in practice patterns with a range of 50-89% of the surgeons performing fewer than 5 cases over the preceding 10 years. There was a significant decrease in surgeon's comfort level with elective pediatric vascular operations compared to the operative management of pediatric vascular trauma (P = 0.0025).

CONCLUSIONS

Most vascular surgeons do not feel comfortable in the operative management of pediatric vascular disease, and optimal resource availability within pediatric CHs may be lacking. Centralized care of this patient population may be warranted.

Perioperative Outcomes From the Prospective Multicenter Least Invasive Fast-Track EVAR (LIFE) Registry

Purpose: To determine the feasibility, perioperative resource utilization, and safety of a fast-track endovascular aneurysm repair (EVAR) protocol in well-selected patients. Methods: Between October 2014 and May 2016, the LIFE (Least Invasive Fast-track EVAR) registry ( ClinicalTrials.gov identifier NCT02224794) enrolled 250 patients (mean age 73±8 years; 208 men) in a fast-track EVAR protocol comprised of bilateral percutaneous access using the 14-F Ovation stent-graft, no general anesthesia, no intensive care unit (ICU) admission, and next-day discharge. The primary endpoint was major adverse events (MAE) through 30 days. The target performance goal for the MAE endpoint was 10.4%. Results: Vascular access, stent-graft delivery, and stent-graft deployment success were 100%. A total of 216 (86%) patients completed all elements of the fast-track EVAR protocol. Completion of individual elements was 98% for general anesthesia avoidance, 97% for bilateral percutaneous access, 96% for ICU avoidance, and 92% for next-day discharge. Perioperative outcomes included mean procedure time of 88 minutes, median blood loss of 50 mL, early oral nutrition (median 6 hours), early mobilization (median 8 hours), and short hospitalization (median 26 hours). Fast-track EVAR completers had shorter procedure time (p<0.001), less blood loss (p=0.04), faster return to oral nutrition (p<0.001) and ambulation (p<0.01), and shorter hospital stay (p<0.001). With 241 (96%) of the 250 patients returning for the 30-day follow-up, the MAE incidence was 0.4% (90% CI 0.1% to 1.8%), significantly less than the 10.4% performance goal (p<0.001). No aneurysm rupture, conversion to surgery, or aneurysm-related secondary procedure was reported. There were no type III endoleaks and 1 (0.4%) type I endoleak. Iliac limb occlusion was identified in 2 (0.8%) patients. The 30-day hospital readmission rate was 1.6% overall. Conclusion: A fast-track EVAR protocol was feasible in well-selected patients and resulted in efficient perioperative resource utilization with excellent safety and effectiveness.

Femorofemoral Arterial Bypass: Subcutaneous or Preperitoneal

A salutary, long-term result, using preperitoneal placement in a patient transferred after repeated failure of subcutaneous prosthetic femorofemoral bypass, prompted a review of this procedure by the authors.

From 1972 to 1996, 61 men and 1 woman, aged 28 to 80 years, received 67 initial or “redo” interpositions for unilateral, predominately-sinistral ischemia, 45% being operated on as emergencies. They were considered unfit for the preferred direct transabdominal reconstruction under general anesthesia because of cardiopulmonary comorbidity. Follow up, extending to 20 years, was complete in 93.5%. Operative mortality was 6.6%, all from cardiogenic shock after atherothromboembolism secondary to transfemoral intraaortic balloon pulsation after myocardial infarction (MI) or coronary artery bypass graft (CABG). Most bypasses were subcutaneous; however, 17% were preperitoneal. The author's cumulative initial patency was similar for those operated on with primary (23) and postaortofemoral bypass graft (post-AFBG) (29) ischemia. Preperitoneal placement (10) was associated with better primary prosthetic patency and less infection than subcutaneous (42) insertion.

Techniques for Managing Complications of Arterial Closure Devices

According to data reported by the American Heart Association, more than 5 million diagnostic and therapeutic catheterizations are performed each year in the United States. The number of catheterizations has tripled since 1979. It has been estimated that complications related to the access site result in more than 75,000 surgical procedures annually. Thus, improved management of the access site itself is essential to achieve the greater goals of improved care and reduced cost. Manual compression directly over the site of arterial puncture usually results in adequate hemostasis but has several significant drawbacks. Manual compression is uncomfortable for the patient, is fatiguing and time-consuming for staff, and necessitates several hours of costly in-hospital observation. In addition, it may be ineffective in achieving hemostasis, especially in the setting of systemic anticoagulation or following the use of large-bore devices. Based on the perceived need for an improved method of managing the arterial access site following catheterization, various vascular sealing devices have been developed. There are at least 8 (and the number is increasing) hemostatic vascular closure devices that are currently approved by the FDA for access site closure after femoral arterial catheterization. The chief advantage attributed to vascular sealing devices is accelerated access site hemostasis, even in the setting of anticoagulation, leading to earlier ambulation and hospital discharge following arterial catheterization. The most important drawbacks related to vascular sealing devices include the cost of the devices and the possibility of increased access site complications. Despite the paucity of properly designed studies supporting their use, it is estimated that over one million vascular sealing devices are used annually in the United States, a number that has increased dramatically in the past 5 years.In this review, we present a brief description of the design and function of the most widely used devices, describe the most common mechanisms of failure, and recommend strategies for management of access site complications including hemorrhage, arterial obstruction, and infection.

The Effects of Toradol on Postoperative Intimal Hyperplasia in a Rat Carotid Endarterectomy Model: Laboratory Research

Carotid endarterectomy (CEA) and more recently carotid artery stenting are the treatments of choice for atherosclerotic disease of the extracranial carotid arteries; however, early restenosis caused by neointimal hyperplasia confounds surgical therapy. Oxidative stress has been implicated in the progression of intimal hyperplasia. The authors hypothesized that ketorolac tromethamine (Toradol), a nonsteroidal antiinflammatory drug that is a potent cyclooxygenase inhibitor, would decrease oxidative stress and thereby reduce intimal hyperplasia in a rat CEA model. Twenty-nine male Sprague-Dawley rats underwent CEA and were divided into 3 treatment groups as follows: (1) control (placebo), (2) 7.5 mg/kg Toradol, and (3) 10 mg/kg Toradol. Toradol treatment began 2 days before CEA and continued for 2 weeks. Two weeks after endarterectomy, carotid arteries were fixed, harvested, and examined for platelet activity (platelet reactive units), oxidative stress (malondialdehyde and glutathione), and intimal hyperplasia (measured as percentage of luminal stenosis). Platelet activity, malondialdehyde and glutathione, and intimal hyperplasia were all significantly lowered in both 7.5- and 10-mg/kg doses of Toradol versus control. Toradol given daily beginning 2 days before CEA and ending 2 weeks after the procedure was effective at significantly reducing platelet activity, oxidative stress, and intimal hyperplasia development in the rat without any increase in bleeding. Although the mechanism of action of this reduction is not completely understood, one possible explanation may be through the inhibition of reactive oxygen species production.

Percutaneous Isolated Limb Perfusion with Thrombolytics for Severe Limb Ischemia

Patients with severe tibioperoneal disease are poor candidates for a distal bypass. Absence of a distal target, lack of conduit, or multiple medical problems can make these patients a prohibitive risk for revascularization. Acute on chronic ischemia in this group poses a greater challenge. Thrombolytic therapy for acute ischemia can be prolonged and carries a significant risk of bleeding if continued beyond 24 hours. However, if the ischemic limbs can be isolated from the systemic circulation, a higher dose of the lytic agent can be given with lower risk. These are the initial results of a series of 10 patients who underwent percutaneous isolated limb perfusion with a high dose of thrombolytics for severe ischemia. Ten patients (lower extremity 8 and upper extremity 2) presented with severe limb-threatening ischemia. Mean ankle/brachial index (ABI) was 0.15 for the lower extremity, and there were no recordable digital pressures in patients with upper extremity ischemia. No distal target was visible on the initial arteriogram. These patients were then taken to the operating room, and under anesthesia, catheters were placed in an antegrade fashion via femoral approach in the popliteal artery and vein percutaneously. For upper extremity, the catheters were placed in the brachial artery and vein. A proximal tourniquet was then applied. This isolated the limb from the systemic circulation. Heparinized saline was infused through the arterial catheter while the venous catheter was left open. A closed loop or an isolated limb perfusion was confirmed when effluent became clear coming out of the venous port. A high dose of thrombolytic agent (urokinase 500,000 to 1,000,000 U) was infused into the isolated limb via the arterial catheter and drained out of the venous catheter. After 45 minutes, arterial flow was reestablished. In 4 patients, Reopro ® was used in addition to thrombolytics. Postprocedure angiograms showed minimal changes, but patients exhibited marked clinical improvement. The ABI changed from 0.15 to 0.5 in the lower extremity and near-normal digital pressures in upper extremity ischemia. Limb salvage and symptomatic relief at 6 months was 90%. All patients except one were kept on anticoagulation postoperatively. No bleeding complications were observed from the procedure. Percutaneous isolated limb perfusion brought symptomatic relief to patients presenting with acute on chronic limb ischemia. This can be an alternate option for patients facing amputation with no revascularization options.

Pravastatin and Clopidogrel Combined Inhibit Intimal Hyperplasia in a Rat Carotid Endarterectomy Model

Intimal hyperplasia, resulting from a complex cascade of events involving platelets, leukocytes, and smooth muscle cells, may be inhibited by the HMG-CoA reductase inhibitor pravastatin, which demonstrates inhibition of platelet activity and leukocyte adhesion and may be associated with inhibition of vascular smooth muscle cell proliferation and migration. Clopidogrel, an adenosine diphosphate (ADP) receptor inhibitor, was shown to decrease platelet activity and aggregation but not intimal hyperplasia (IH). We postulated that the combination of both pravastatin and clopidogrel would significantly decrease IH in a rat carotid endarterectomy model. Male Sprague-Dawley rats (n = 18) divided by treatment regimen underwent treatment for 2 weeks both before and after an open carotid endarterectomy. Serum collected at the time of harvest was measured for C-reactive protein (CRP), platelet activity, and total serum cholesterol; carotid arteries were removed and processed for IH determination. Control rats (n = 7) received oral vehicle daily before and following endarterectomy. Pravastatin-alone rats (n = 6) received oral pravastatin (10 mg/kg/day) before and after endarterectomy. Pravastatin plus clopidogrel rats (n = 5) received oral pravastatin (10 mg/kg/day) plus a preendarterectomy bolus of oral clopidogrel (4.3 mg/kg) before endarterectomy and resumed pravastatin (10 mg/kg/day) plus oral clopidogrel (1 mg/kg/day) postendarterectomy. Pravastatin alone and pravastatin plus clopidogrel significantly decreased CRP compared to controls (120.2 ±11.2 and 134.1 ±9.9 vs 191.1 ±9.2 µg/mL, respectively p = 0.003 and p = 0.0024). CRP levels were not different between pravastatin alone and pravastatin plus clopidogrel (p = 0.35). Platelet activity was significantly decreased by pravastatin alone and pravastatin plus clopidogrel in comparison to controls (7.3 ±2.2 and 6.6 ±2.8 vs 19.2 ±6.1 platelet reactive units (PRU), respectively p = 0.048 and p = 0.045). No significant difference was noted in platelet activity between pravastatin alone and pravastatin plus clopidogrel (p = 0.89). Pravastatin plus clopidogrel significantly reduced serum cholesterol compared to control and pravastatin alone (84.0 ±6.6 vs 110.4 ±7.4 and 117.0 ±8.8 mg/dL, respectively p = 0.03 and p = 0.01). Pravastatin alone did not decrease serum cholesterol compared to controls (p = 0.54). IH was not reduced by pravastatin alone compared to controls (p = 0.61) but was significantly decreased by pravastatin plus clopidogrel in comparison to control and pravastatin alone (3.0 ±1.1 vs 46.3 ±13.7 and 37.4 ±14.6% luminal stenosis, respectively p = 0.01 and p = 0.05). Pravastatin plus clopidogrel significantly decreased CRP, platelet activity, total serum cholesterol, and IH while pravastatin alone decreased only CRP and platelet activity. Intimal hyperplasia reduction may therefore be dependent on other contributors, possibly growth factors, cytokines, and oxidative stress. The combination of pravastatin plus clopidogrel may have synergistic or even additional inhibitory effects on IH. Pravastatin plus clopidogrel was effective in decreasing IH in a rat carotid endarterectomy model and may prove a useful therapy for IH reduction in the clinical setting.

Assessment of Apparent Vena Caval Penetration by the Greenfield Filter

Purpose:

To examine and elucidate the mechanisms for apparent “penetration” by Greenfield vena caval filters.

Methods:

Two filters were placed in the inferior venae cavae (IVC) of four immature sheep and followed with cavography for 1 year. Two animals underwent computed tomography (CT) and laparoscopic examination. At necropsy, the vena cava and adjacent structures of all four animals were examined grossly and histologically.

Results:

Based upon cavography and CT imaging, all filters appeared to penetrate the vena cava at 12 months. However, at laparoscopy, no hooks or limbs were exposed, and the pericaval tissues remained intact; each hook or limb was within the adventitia or encapsulated in scar tissue. Histology of the tissue at the hook sites revealed remodeling of the intimal surface of the IVC and thinning of the adventitia.

Conclusions:

Based upon these data, we hypothesize that the vena cava gradually adapts by medial and adventitial thinning and myointimal remodeling to the radial force exerted by a filter. This process allows increase in the filter base diameter while maintaining the integrity of the cava and protecting adjacent structures.

Effect of Clopidogrel on Platelet Aggregation and Intimal Hyperplasia following Carotid Endarterectomy in the Rat

Intimal hyperplasia results in significant morbidity and mortality following vascular intervention. Both platelets and elevated homocysteine have been implicated in the development of intimal hyperplasia. We previously demonstrated that a locally applied antiplatelet agent decreases the development of intimal hyperplasia. We were therefore interested in a systemic antiplatelet agent, clopidogrel. We hypothesized that clopidogrel would decrease platelet aggregation and activity and intimal hyperplasia. Male Sprague-Dawley rats underwent carotid endarterectomy (CEA) and treatment with either placebo or varying regimens of clopidogrel, including chronic, pre-CEA bolus, chronic plus pre-CEA bolus, and chronic plus post-CEA bolus; a homocystine diet was used to elevate both plasma homocysteine and the degree of intimal hyperplasia. Platelet aggregation, platelet activity, and intimal hyperplasia were then assessed. Platelet aggregation was not decreased with chronic clopidogrel; however, it was decreased with pre-CEA bolus clopidogrel. Similarly, platelet activity was not inhibited by chronic clopidogrel but was inhibited by pre-CEA and chronic plus pre-CEA bolus clopidogrel. Neither chronic, pre-CEA bolus, chronic plus pre-CEA bolus, nor chronic plus post-CEA bolus clopidogrel resulted in a decrease in intimal hyperplasia. Although pre-CEA bolus clopidogrel resulted in a decrease in both platelet aggregation and activity, it was unable to decrease the development of intimal hyperplasia at any dose. Additional factors must therefore contribute to the pathologic development of intimal hyperplasia.

Outcomes after retroflexed gracilis muscle flap for vascular infections in the groin

OBJECTIVE

Multiple catheterizations and procedures on the femoral arteries can increase the risk of infection and eventual destruction of the overlying skin and subcutaneous tissue. Without adequate tissue coverage, vascular structures are exposed and, thus, vulnerable to disruption. This can lead to loss of limb and/or life and carries a significant mortality. We hypothesized that gracilis muscle flap (GMF) was a reliable adjunct in providing healthy tissue coverage for a complex surgical problem.

METHODS

Retrospective review of charts was performed on all patients who had undergone GMF for groin infections at a tertiary care medical center.

RESULTS

From 1997 to 2012, GMF was performed in 68 limbs (64 patients) by vascular surgeons for infectious etiology to cover the common femoral artery. At the time the GMF was placed, the femoral artery had synthetic graft/patch in 14 limbs, whereas 54 limbs had procedures with autologous conduit. Complete healing was achieved in 58 (85%) limbs. Treatment was deemed not successful in 10 limbs where patients continued to have persistent infection. Six out of 10 limbs had anastomosis disruption requiring emergent ligation of the common femoral artery. Nine patients died during the perioperative period (30-day). There were a total of 13 amputations in 12 patients. Limb salvage was achieved in 55 limbs (81%). Univariate analysis suggested that patients that had revascularization procedures with synthetic graft had a higher complication rate compared with autologous/vein reconstruction (24% vs 5%; P = .021). This group also has a higher rate of persistent infection compared with the autologous group (24% vs 2%; P = .006). Patients older than 75 years at the time of GMF had a higher incidence of GMF-related complications (57% vs 5%; P = .04). Multivariate analysis confirmed that presence of prosthesis led to higher incidence treatment failures and muscle flap complications at the surgical site (odds ratio, 6.6; P = .04; and odds ratio, 13.3; P = .03, respectively).

CONCLUSIONS

GMF is technically simple to perform and provides durable soft tissue coverage with a high rate of healing for complex groin wounds even in the presence of synthetic conduit.

Management of noninfected prosthetic aortic bypass failures using femoral vein

OBJECTIVE

The use of femoral-popliteal vein as a conduit to treat infected aortoiliac pathologies has been described extensively and is referred to as the neoaortoiliac system procedure. We examined our center's outcomes after using deep vein as a conduit for the salvage of failed aortofemoral prosthetic bypasses in patients without infection.

METHODS

Procedures using femoral vein as conduit at the University of Arkansas for Medical Sciences between January 2005 and July 2013 were retrospectively reviewed (n = 110). Patients were excluded if the reconstruction was for infectious etiologies (n = 71) or for nonaortofemoral reconstructions (n = 31). Operative variables, complications, and patency rates were collected.

RESULTS

Femoral vein was used to revascularize failed aortobifemoral bypasses in eight patients. Indications included rest pain (n = 7) and short-distance claudication (n = 1). Reconstructions identified two patients each with aortobifemoral bypass or aortofemoral bypass, and one patient each with aortofemoral bypass with femorofemoral bypass, aorotoiliac bypass, iliofemoral bypass with femorofemoral bypass, or ilioprofunda bypass. Mean follow up was 27.5 months. There were no major postoperative complications. Symptoms secondary to deep vein harvest (swelling/dermatitis) developed in three of eight patients. The average ankle-brachial index improved from 0.33 to 0.73 (P = .003), with a limb salvage rate of 100%. Kaplan-Meier analysis found primary patency was 70% at 1 year and 53% at 5 years, which improved to 100% and 75%, respectively, with secondary measures.

CONCLUSIONS

Despite a need for secondary interventions and venous hypertension syndromes, deep vein offers good patency and excellent limb salvage after failed prosthetic aortoiliac bypasses.

Preservation of pelvic perfusion in endovascular aneurysm repair

Endovascular aneurysm repair requires a suitable anatomy for placement of covered stent grafts, which includes a non-aneurysmal distal landing zone within the common iliac arteries. Patients with iliac artery aneurysms, thus, are often not candidates for this minimally invasive repair, as extension of the graft to an appropriate site would cover the internal iliac artery and result in significant symptoms related to poor pelvic perfusion. We present two cases of common iliac artery aneurysms treated by modified endovascular techniques with good results. Select patients with iliac artery aneurysms may be candidates for endovascular repair. These patients should be referred to centers familiar with these techniques.

Estrogen replacement attenuates exaggerated neointimal hyperplasia following carotid endarterectomy in rats

BACKGROUND

To investigate whether estrogen may attenuate neointima formation in hyperhomocysteinemic rat carotid endarterectomy.

METHODS

Rats were divided into 6 groups: ovariectomized estradiol-treated homocysteine or chow; ovariectomized placebo-treated homocysteine or chow; intact placebo-treated homocysteine or chow. Chow served as controls while homocysteine served as exaggerated intimal hyperplasia. Prior to endarterectomy, rats were implanted with estradiol mini-pump or placebo, diets given 2 weeks before and after surgery. Homocysteine, estrogen, and neointimal hyperplasia were determined.

RESULTS

Homocysteine was elevated in homocysteine groups versus controls except in estradiol-treated group. Intimal hyperplasia increased in placebo-treated ovariectomized homocysteine versus intact group. Exaggerated intimal hyperplasia in placebo-treated ovariectomized homocysteine was reduced by estrogen and so was homocysteine. Estrogen replacement in ovariectomized homocysteine group reduced intimal hyperplasia to that of intact or ovariectomized controls.

CONCLUSION

Estradiol treatment in this ovariectomized hyperhomocysteinemia carotid endarterectomy and resultant attenuation of homocysteine and neointima may have relevance to the beneficial effects of estrogen on hyperplastic response.

The effects of acarbose treatment on intimal hyperplasia in a rat carotid endarterectomy model of diet-induced insulin resistance

BACKGROUND

Increased carotid restenosis due to revascularization therapy is associated with insulin resistance. We hypothesize that glucose control using acarbose may attenuate intimal hyperplasia in rat carotid endarterectomy model of diet-induced insulin resistance.

METHODS

Rats were fed low-fat complex carbohydrate (control) or high-fat sucrose (insulin resistance) for 4 months. Three days preoperatively, some high-fat-sucrose rats were on acarbose, remainder of the rats received placebo. Rat carotids were assessed with duplex pre-and postoperatively. Acarbose and placebo continued for 2 weeks. Glucose, insulin, blood flow velocities and intimal hyperplasia were determined.

RESULTS

High-fat sucrose plus acarbose attenuated intimal hyperplasia. Post-drug high-fat sucrose glucose decreased. Blood flow velocities postoperatively elevated above baseline. High-fat sucrose increased blood flow velocities postoperatively, which was attenuated with acarbose.

CONCLUSION

Glucose control by acarbose in rat carotid endarterectomy model of diet-induced insulin resistance resulted in attenuation of intimal hyperplasia.

Definitive Test to Diagnose Median Arcuate Ligament Syndrome: Injection of Vasodilator During Angiography

The diagnosis of median arcuate ligament (MAL) syndrome and its correlation with symptoms has been controversial since the disease entity was described. The authors describe a technique that will identify patients who will benefit from intervention. Eight patients with isolated celiac artery compression from MAL were identified by the authors. Their technique involved selective cannulation of the superior mesenteric artery (SMA) and injection of a vasodilator during angiography. Symptom reproduction and loss of collateral filling of the celiac territory represented a positive test: 4 of the 8 patients had a positive test and underwent successful surgical treatment of the condition; 3 of them remained asymptomatic at follow-up; 1 patient continues to have mild abdominal discomfort. Of the 4 patients with a negative test, 2 were found to have other conditions causing their symptoms. Vasodilator injection into the SMA is a useful diagnostic test to identify patients with symptomatic MAL syndrome.

Delayed manifestation of abdominal aortic stenosis in a child presenting 10 years after blunt abdominal trauma

We report the case of a 13-year-old boy who, at 3 years of age, was a rear seat-restrained passenger in a high-speed motor vehicle crash necessitating segmental small-bowel resection. The patient remained well for 10 years; then he began to have exercise-induced fatigue in his lower extremities. Routine physical examination revealed a bruit and thrill in the mid abdomen and diminished femoral pulses. Aortic stenosis was diagnosed and treated surgically. We discuss the pathophysiology of the lesion and review the literature. This is the first report of abdominal aortic stenosis 10 years after blunt abdominal trauma in a child.

Homocysteine-induced vascular dysregulation is mediated by the NMDA receptor

Elevated plasma homocysteine accelerates myointimal hyperplasia and luminal narrowing after carotid endarterectomy. N-methyl D aspartate receptors (NMDAr) in rat cerebrovascular cells are involved in homocysteine uptake and receptor-mediated stimulation. In the vasculature, NMDAr subunits (NR1, 2A-2D) have been identified by sequence homology in rat aortic endothelial cells. Exposure of these cells to homocysteine increased expression of receptor subunits, an effect that was attenuated by dizocilpine (MK801), a noncompetitive NMDA inhibitor. The objective of this study was to investigate the existence of an NMDAr in rat vascular smooth muscle (A7r5) cells, and also the effect of homocysteine on vascular dysregulation as mediated by this receptor. Subunits of the NMDAr (NR1, 2A-2D) were detected in the A7r5 cells by using the reverse transcriptase polymerase chain reaction and Western blotting. Homocysteine induced an increase in A7r5 cell proliferation, which was blocked by MK801. Homocysteine, in a dose and time dependent manner, increased expression of matrix metallinoproteinase-9 and interleukin-1beta, which have been implicated in vascular smooth muscle cell migration and/or proliferation. Homocysteine reduced the vascular elaboration of nitric oxide and increased the elaboration of the nitric oxide synthase inhibitor, asymmetric dimethylarginine. All of these homocysteine mediated effects were inhibited by MK801. NMDAr exist in vascular smooth muscle cells and appear to mediate, at least in part, homocysteine-induced dysregulation of vascular smooth muscle cell functions.

Identification of a homocysteine receptor in the peripheral endothelium and its role in proliferation

BACKGROUND

Homocysteine, a risk factor for atherosclerosis, increases intimal hyperplasia after carotid endarterectomy with associated smooth muscle cell proliferation and modulation of cytokines. The N-methyl-D-aspartate receptor (NMDAr), a glutamate-gated ion channel receptor, is associated with homocysteine-induced cerebrovascular injury; however, the receptor has not been identified in peripheral vascular cells, nor has any interaction with homocysteine been clarified. Our objectives were first, to identify NMDAr in rat carotid artery and rat aorta endothelial cells (RAEC); and second, to determine whether homocysteine activates NMDAr in the endothelium.

METHODS

NR1 and NR2A, two NMDAr subunits, were probed in rat carotid arteries by immunohistochemistry. RNA was isolated from RAECs, and expression of all NMDAr subunits (NR1, 2A, 2B, 2C, and 2D) were examined by RT-PCR and sequencing. For receptor protein expression, RAEC were incubated with different homocysteine concentrations and incubation times and also were treated with 50 microM homocysteine and/or preincubated with 50 microM dizocilpine MK-801, an NMDAr inhibitor.

RESULTS

Both NR1 and NR2A were expressed in rat carotid arteries. All NMDAr subunits were expressed in the RAECs, and there was 92% to 100% similarity compared with rat NMDAr from the National Center for Biotechnology Information (NCBI) GenBank. Homocysteine upregulated NR1 expression and increased cell proliferation. RAEC pretreatment with MK-801 reduced homocysteine-mediated cell proliferation.

CONCLUSION

This study is the first to show that NMDAr exists in the peripheral vasculature, and that homocysteine may act via NMDAr to increase intimal hyperplasia.

CLINICAL RELEVANCE

Our objectives included the identification of a homocysteine receptor in the peripheral vasculature. The possible inhibition of a homocysteine receptor to prevent intimal hyperplasia rather than treat established stenosis would make a significant clinical impact. This will open further avenues of study in determining the role of homocysteine in the pathogenesis of intimal hyperplasia.

Saratin (an inhibitor of platelet-collagen interaction) decreases platelet aggregation and homocysteine-mediated postcarotid endarterectomy intimal hyperplasia in a dose-dependent manner

BACKGROUND

This study investigated Saratin's (Merck KGaA, Darmstadt, Germany) prevention of platelet adhesion and intimal hyperplasia at different doses and in the hyperhomocystinemia rat carotid endarterectomy (CEA) model.

METHODS

Rats were divided into two groups: (1) platelet adhesion or (2) luminal stenosis because of intimal hyperplasia. At CEA, rats received 0, 0.5, 5.0, 10.0, or 20.0 microg Saratin on the artery. Post-CEA platelet aggregation was evaluated by standard error of the mean. Intimal hyperplasia group received either (1) control or (2) 4.5 g/kg DL-homocystine diets for two weeks followed by CEA and treated with diluent or 5.0 microg Saratin. Endpoints included platelet adhesion, intimal hyperplasia, plasma homocysteine (HCys), and its metabolic enzymes cystathionine beta-synthase (CBS) and methylenetetrahydrofolate reductase (MTHFR).

RESULTS

Platelet adhesion: post-CEA, platelet adhesion was reduced by 63%, 67%, and 67% in Saratin doses > or =5.0 microg. Intimal hyperplasia: 5.0 microg Saratin in the HCys group decreased intimal hyperplasia by 45% compared with the non-Saratin-treated HCys group. Plasma HCys levels were not altered with Saratin treatment in the HCys groups nor were CBS or MTHFR.

CONCLUSIONS

Saratin significantly inhibited platelet adhesion at > or =5.0 microg, and Saratin at 5.0 microg attenuated luminal stenosis in a hyperhomocysteinemic rat CEA model.

Plasma homocysteine measurements after carotid artery manipulation and clamping in a rat CEA model

OBJECTIVE

The effect of a rat carotid endarterectomy (CEA) on homocysteine and the metabolic enzymes methylenetetrahydrofolate reductase (MTHFR) and cystathionine beta-synthase (CBS) was studied.

METHODS

Rats were placed into 7 groups: (1) no anesthesia (NA), (2) anesthesia only (AO), (3) skin opened and closed (O/C), (4) skin opened with exposure of the carotid artery and closed (O/E/C), (5) carotid isolated and clamped (CO), (6) open CEA, and (7) open femoral endarterectomy (FEA). End points included homocysteine, hepatic MTHFR, and CBS activity.

RESULTS

Homocysteine in the NA, AO, O/C, O/E/C, and FEA were low and not different. CEA produced a 6-fold increase in homocysteine when compared with non-CEA groups. Specifically, CEA produced an increase in homocysteine versus the AO group at 2 weeks (11.3 +/- 0.7 vs 2.1 +/- 0.9 micromol/L;P < .001), 4 weeks (8.9 +/- 0.7 vs 3.5 +/- 0.9 micromol/L; P = .004) and 6 weeks (7.7 +/- 0.9 vs 3.1 +/- 1.5 micromol/L; P = .03). The CO group had increased homocysteine versus the O/C, O/E/C, and FEA, but was lower than the CEA group. CEA produced an increase in MTHFR and CBS versus the AO group.

CONCLUSIONS

CEA resulted in elevated levels of homocysteine; however, when broken down into its component parts, no elevation was observed except for a small increase with the CO procedure. Manipulation of the femoral artery did not raise homocysteine levels. The increase in homocysteine is possibly due to the combination of vessel wall damage and changes in cerebral blood flow dynamics.

Cigarette smoke increases intimal hyperplasia and homocysteine in a rat carotid endarterectomy

BACKGROUND

Homocysteine and smoking are independent risks for CVD; however their importance in post-CEA intimal hyperplasia is unclear. We performed a CEA in rats exposed to cigarette smoke with the hypothesis that smoking would increase intimal hyperplasia that may be associated with an elevated serum homocysteine. Folic acid (FA) and the homocysteine metabolic enzymes MTHFR and CBS were used to test for the significance of homocysteine elevation.

MATERIALS AND METHODS

Rats underwent an open CEA. N = 13 rats received smoke exposure 2 weeks prior, and 2 weeks post-CEA and N = 12 received no smoke. Each group was divided into either control or an FA-added diet resulting in four groups. Rats were sacrificed at 2 weeks post-CEA; liver, urine, blood, and carotid arteries samples were obtained.

RESULTS

Smoked rats had increased urinary peak and trough cotinine levels versus non-smoke rats, which decreased with FA. Smoke exposure increased intimal hyperplasia versus non-smoke controls by nearly 120% (57.8 +/- 6.2 versus 26.8 +/- 5.4% luminal stenosis, P = 0.005). Smoke-exposed rats had an increased serum homocysteine versus non-smoke controls (8.3 +/- 0.8 versus 5.7 +/- 0.8 microm, P = 0.014). Smoked rats given FA had decreased serum homocysteine compared to the smoke group. Along with reductions in homocysteine, FA eliminated the increase in intimal hyperplasia seen with smoke exposure (33.5 +/- 6.1 versus 57.8 +/- 6.2% luminal stenosis, P = 0.03). CBS activity decreased in smoked rats by nearly 20% versus non-smoke rats. FA supplementation in smoked rats both (1) increased CBS activity and (2) decreased MTHFR compared to control non-smoke-exposure levels.

CONCLUSION

Smoking increases plasma homocysteine and post-CEA intimal hyperplasia. This suggests homocysteine has an etiological role in the intimal hyperplasia increase observed with smoking, since both were negated with FA.

Major lower extremity amputations at a Veterans Affairs hospital

BACKGROUND

This study was made to evaluate the experience at a Department of Veterans Affairs (VA) hospital with consecutive major lower extremity amputations over a period of 7 years.

METHODS

The records of 229 patients (221 male and 8 female) who underwent 296 consecutive major lower extremity amputations (119 above-knee amputations [AKA] and 177 below-knee amputations [BKA]) over a period of 86 months (September 1994 to October 2001) were retrospectively analyzed. All amputations were performed by members of the vascular surgery department.

RESULTS

Forty of the 229 patients (17%) eventually required a contralateral amputation, 27 patients (12%) had BKAs that eventually necessitated conversion to AKA, and 44 amputations (15%) required an initial guillotine amputation. The 30-day mortalities for BKA, AKA, and BKA to AKA operations were 12%, 17%, and 7%, respectively. Eighty-eight of the amputations (30%) developed wound complications, and required 137 revisions. Seventy-seven of the amputations (26%) had undergone prior revascularization, of which 31 (48%) had an early failed bypass. The average preoperative ankle/brachial index (ABI) was 0.57. Of the patients undergoing amputation, 97 (42%) complained of rest pain, 91 (40%) complained of claudication, and 158 (69%) had tissue loss or gangrene at the time of their operation. One hundred and forty-six patients (64%) were diabetic. Twenty-two patients (9%) were dialysis dependent and 81 patients (35%) admitted to smoking. Of the known causes of death, 21 resulted from myocardial infarction, 22 from congestive heart failure, 14 from respiratory failure, 13 from disseminated cancer, 10 from sepsis, 7 from stroke, and 6 from renal failure. Preoperative functional status determinations revealed that of 272 patients with enough information to assess functional status, 43 were totally dependent, 97 were partially independent, and 132 were independent. Of the 229 patients, 168 (73%) were ambulatory prior to their amputation, and at the completion of this review only 53 patients (23%) were ambulatory.

CONCLUSIONS

Most patients undergoing major lower extremity amputations have many comorbidities; hence morbidity and mortality rates are high, with the most common causes of death being cardiac and respiratory in nature. These data suggest that major lower extremity amputations highlight a very high-risk population with only 39% survival at 7 years, as well as a costly subset secondary to prolonged hospitalization times (average 15 days, range 3 to 105), in addition to the extraordinary cost associated with diminished functional status.

Saratin, an inhibitor of collagen-platelet interaction, decreases venous anastomotic intimal hyperplasia in a canine dialysis access model

Prosthetic dialysis access thrombosis and/or stenosis is the most common cause of graft impairment or loss and is primarily attributed to venous outflow stenosis due to intimal hyperplasia. Intimal hyperplasia is thought to result from interactions between areas of exposed subendothelial collagen in an injured vessel and platelets, resulting in platelet adhesion. Saratin, an inhibitor of the vWF-dependent binding of platelet to collagen interaction, has been shown in vitro to reduce the adhesion of platelets to collagen. In the current study, the authors investigated the effects of topical saratin administration in a canine dialysis access model in regard to intimal hyperplasia development at the venous anastomosis. Fourteen female mongrel dogs underwent placement of a femoral polytetrafluoroethylene (PTFE) dialysis access graft and were placed into 1 of 2 groups: 1) control or 2) experimental with topical saratin application. The experimental group had 600 microg of saratin (1 microg/microL) applied for 5 minutes directly onto the venous anastomosis before restoration of blood flow;control groups received vehicle control. At 4 weeks postoperative, a portion of the graft was removed along with a segment of the outflow vein. Veins were subsequently processed, sectioned, and analyzed along the length of the excised segment and divided into blocks that included the area of the graft toe, midanastomotic region and heel, and blocks A-E. Intimal hyperplasia was assessed by a computer-assisted morphometric analysis. Platelet counts and bleeding times were also measured. Vein segments in the control group (n=7) showed pronounced intimal hyperplasia in blocks B, C, and D as compared to the saratin group (n=6). Distribution of intimal hyperplasia by blocks between control and saratin groups were as follows: block [A] 8.6 +/- 1.9 vs 9.7 +/- 3.0% (p=NS), [B] 32.7 +/- 6.3 vs 10.7 +/- 3.5% (p=0.01), [C] 44.8 +/- 6.2% vs 10.3 +/- 1.5% (p=0.0004), [D] 40.8 +/- 11.0 vs 9.1 +/- 4.2% (p=0.02), [E] 7.5 +/- 5.5 vs 2.7 +/- 0.4% (p=NS). Intimal hyperplasia normalized to vein wall thickness also showed a significant reduction with saratin application. Bleeding times and platelet counts obtained at different time points during the experiment showed no difference between control and saratin groups. In a canine dialysis access model using PTFE grafts, topical application of saratin at the venous anastomosis decreased intimal hyperplasia development by as much as 77% when compared with control animals. Saratin provides for a method of substantially reducing intimal hyperplasia by direct local application without systemic side effects.

Intimal hyperplasia following carotid endarterectomy in an insulin-resistant rat model

Hyperhomocysteinemia, a known risk factor for cardiovascular disease, results in an elevation of intimal hyperplasia (IH) following a carotid endarterectomy (CEA) in a rat model. An exaggerated IH response following CEA has been observed in rats with dietary induced hyperhomocysteinemia. Type 2 diabetics often present with hyperhomocysteinemia and are at higher risk for developing vascular blockage following surgical procedures. To determine if insulin resistance increases IH risks following endarterectomy, the 3 goals of this study were: (1) to establish plasma homocysteine concentrations in dietary induced insulin-resistant rats and their controls, (2) to investigate whether a positive correlation of IH and plasma homocysteine response occurs following CEA in the insulin-resistant rat model, and (3) if so, to attempt to decrease IH by supplementation with folic acid, a known enzymatic cofactor in the homocysteine metabolic pathway. To achieve these aims, male rats (275 to 300 g) were fed 1 of 4 diets for a 4-month period: (1) high-fat sucrose (HFS), (2) low-fat complex carbohydrate (LFCC), (3) HFS + 25 mg/kg folic acid (HFS+F), or (4) LFCC + 25 mg/kg folic acid (LFCC+F). At the end of the 4-month period the rats underwent an open (non-balloon) unilateral CEA. Two weeks post-endarterectomy, blood, liver and carotid tissue were removed to measure plasma insulin, folic acid, and homocysteine, 2 key enzymes of homocysteine metabolism-methylenetetrahydrofolate reductase (MTHFR) and cystathionine beta-synthase (CBS)-and percent lumenal stenosis (IH%). Computer-assisted morphometric analysis was used to measure the percentage of IH in the carotid artery. Plasma homocysteine was significantly higher in the HFS group when compared with the LFCC group (11.3+/-1.3 micromol/L v 7.4+/-0.6 mircomol/L, P=.008) as was post-endarterectomy IH producing lumenal stenosis (30.7%+/-4.2% v 14.0%+/-4.3%, P=.008). Plasma insulin in the HFS group was higher than the LFCC (control) group and was significant (36.3+/-3.0 microU/mL v 21.1+/-0.8 microU/mL, P=.0004). Folic acid supplementation in the HFS group resulted in reductions of plasma homocysteine (HFS v HFS+F, 11.3+/-1.3 micromol/L v 7.95+/-1.0 micromol/L, P=.02) and post-endarterectomy IH (HFS v HFS+F, 30.7%+/-4.2 % v 10.4%+/-1.6%, P=.0001). The control or LFCC group was not statistically different from the HFS+F group in homocysteine or IH. Folate supplementation did not decrease insulin concentrations in the HFS+F group compared to the LFCC group. We conclude that the HFS diet produced an insulin-resistant state with an elevated plasma homocysteine and an exaggerated IH response following carotid endarterectomy in this rat model. Dietary folate supplementation reduced plasma homocysteine concentrations in the HFS diet, which implicates hyperhomocysteinemia as an etiologic factor in the development of post-CEA IH in this insulin-resistant rat model.

Infectious complications resulting from use of hemostatic puncture closure devices

BACKGROUND

Femoral access site complications have increased as the fields of invasive cardiology, radiology, and endovascular surgery have emerged. In order to address one of these complications, hemorrhage, the hemostatic puncture closure devices were developed.

METHODS

Retrospective review of cardiac catheterizations performed at a single institution to investigate infectious groin complications related to use of the Perclose Prostar and Techstar devices.

RESULTS

Infectious groin complications were significantly higher in the Perclose group as compared with manual compression. Three patients had clinical and laboratory evidence of arterial infection whereas 2 had soft tissue infections. All 5 required operative intervention ranging from incision and drainage to arterial reconstruction. Hemorrhagic complications were not significantly different between the two groups.

CONCLUSIONS

The Perclose devices provide hemostasis after femoral artery catheterization similar to manual compression. However, infectious groin complications appear to be more common with these devices.

Saratin, an inhibitor of von Willebrand factor-dependent platelet adhesion, decreases platelet aggregation and intimal hyperplasia in a rat carotid endarterectomy model

PURPOSE

Post-carotid endarterectomy, thrombosis, and intimal hyperplasia may be decreased by the inhibition of platelet adhesion and activation. In this study, a novel agent, saratin, was used to inhibit platelet-to-collagen adhesion in a rat carotid endarterectomy model. Saratin is a recombinant protein isolated from the saliva of the medicinal leech Hirudo medicinalis, which is thought to act by binding to collagen, and inhibits von Willebrand factor-collagen interaction under conditions of increased shear and therefore, the adherence and activation of platelets at the vessel wall. Saratin has the advantage of being a nonsystemic, site-specific topical application.

METHODS

A rat carotid endarterectomy model was used in which an open technique with arteriotomy and intimectomy was used. Saratin was applied to the endarterectomized surface of the carotid artery before arterial closure. End point measurements included platelet adhesion, thrombosis rate, intimal hyperplasia development, bleeding times, and platelet counts. Electron micrographs of carotid arteries were used for quantitative analysis of platelet aggregation and platelet counts. Intimal hyperplasia and thrombosis were assessed with computer-assisted morphometric analysis of elastin-stained carotid artery sections with direct measurement of the intimal hyperplasia area.

RESULTS

The topical application of saratin significantly decreased platelet adhesion compared with controls at 3 hours after carotid endarterectomy (64 +/- 17 vs 155 +/- 33 platelets per grid, P = .05), and 24 hours after carotid endarterectomy (35 +/- 11 vs 149 +/- 37 platelets per grid, P = .0110), respectively. A percent luminal stenosis, as a measure of intimal hyperplasia, was significantly decreased with saratin application compared with controls (10.9% +/- 1.8% vs 29.8% +/- 6.8%, P = .0042). This decrease in intimal hyperplasia formation correlated with the inhibition of platelet adhesion. Thirty-three percent of control arteries were found to be thrombosed 2 weeks after carotid endarterectomy compared with a 0% thrombosis rate in the saratin-treated group (P = .0156). No increased bleeding was encountered along the arterial suture line in the saratin group. Bleeding times and systemic platelet counts were not found to change significantly in the saratin-treated rats compared with control rats at 3 and 24 hours after endarterectomy.

CONCLUSION

Saratin significantly decreased platelet adhesion, intimal hyperplasia, luminal stenosis, and thrombosis after carotid endarterectomy in rats. Saratin did not increase suture line bleeding or bleeding times, and did not decrease platelet counts. Saratin may serve as a topical agent to be used for the site-specific inhibition of thrombosis and intimal hyperplasia after vascular manipulation.

Increasing levels of dietary homocystine with carotid endarterectomy produced proportionate increases in plasma homocysteine and intimal hyperplasia

PURPOSE

The role that homocysteine may play in post-carotid endarterectomy (CEA) restenosis due to intimal hyperplasia is not well understood. This study was designed to investigate the effects of different levels of dietary homocystine on: (1) plasma homocysteine; (2) post-CEA intimal hyperplasia; and (3) levels of the methyl donor S-adenosylmethionine (SAM) and its counterpart S-adenosylhomocysteine (SAH) in the homocysteine pathway.

METHODS

Male rats were fed specialized diets for 2 weeks pre- and post-CEA. Groups included control (0 homocystine added, n=9), 1.5 (1.5 g/kg homocystine added, n=10), 3.0 (3.0 g/kg homocystine added, n=9), and 4.5 (4.5 g/kg homocystine added, n=11). The rats underwent a surgical carotid endarterectomy. Endpoints included; plasma homocysteine, intimal hyperplasia, replicative index using with alpha-SM actin and BrdU, hepatic SAM levels, SAH levels, and the hepatic activities of methylenetetrahydrofolate reductase (MTHFR) and cystathionine beta-synthase (CBS).

RESULTS

Increasing dietary homocystine produced a proportionate increase in plasma homocysteine and an increase in intimal hyperplasia. Regression analysis of plasma homocysteine levels and intimal hyperplasia showed a significant correlation (r=0.71,P=0.003). Plasma homocysteine levels above 15 microM were associated with significant increases in intimal hyperplasia above 6.5% (P=0.04). Elevation of plasma homocysteine levels to moderate levels (5-25 microM) resulted in significant post-CEA intimal hyperplasia. Cellular analysis of the area of intimal hyperplasia in all diet groups showed comparable amounts of cells positive for alpha-SM actin. However, with increasing levels of dietary homocystine and plasma homocysteine there was an increase in replicative index (P<0.001) as determined by BrdU staining. Increasing dietary homocystine increased plasma homocysteine and was followed by increases in the replicative index thus producing increased intimal hyperplasia and lumenal stenosis. In hepatic measurements the 1.5 and 3.0 g/kg homocystine diets caused: increased liver activity of MTHFR (P=0.03) and decreased hepatic levels of SAM, SAH and SAM/SAH ratios compared to controls. Homocystine treatment did not cause significant alterations in CBS levels (P=0.992). These studies also showed no correlation of the MTHFR and CBS enzymes with plasma homocysteine levels or intimal hyperplasia. However, hepatic levels of SAM showed significant negative correlations with plasma homocysteine (r=-0.58; P=0.006) and with BrdU percentages of cellular proliferation (r=-0.69; P=0.06).

CONCLUSION

The degree of post-CEA intimal hyperplasia in a rat model is directly related to the plasma level of homocysteine. The hyperplastic effects of homocysteine may be mediated in part by a physiological insufficiency of methyl donors as shown by decreases in SAM. Thus, increasing levels of plasma homocysteine enhanced and accelerated the smooth muscle cell response after CEA which led to increased intimal hyperplasia and lumenal stenosis.

Abdominal aortic aneurysm repair

Newer, minimally invasive catheter-based endovascular technology utilizing stent grafts are currently being evaluated for abdominal aortic aneurysm (AAA) repair. A retrospective review of all (3 years) consecutive, non-ruptured elective AAA repairs was undertaken to document the results of AAA surgical repair in a modern cohort of patients to allow a contemporary comparison with the evolving endoluminal data. One hundred twenty-one AAAs were identified in a male veteran population. Mean age was 68.5 +/-7.7 years. Medical history review showed hypertension in 55%, heart disease in 73.5%, peripheral vascular disease in 21%, stroke and transient ischemic attacks in 22%, diabetes mellitus in 7%, renal insufficiency in 10%, and smoking history in 80%. The AAA size was documented with ultrasound (5.2 +/-1.3 cm, n=40) and computed tomography (5.6 +/-1.3 cm, n=100). Fifty-nine percent had angiography. Intraoperative end points included an operative time of 165 +/-6.3 minutes from incision to dressing placement. A Dacron tube graft was used in 78%, the remaining were Dacron bifurcated grafts. A suprarenal clamp was used in 8% for proximal aortic control with juxtarenal aneurysms. A pulmonary-artery catheter was placed in 69%. A transverse incision was used in 69% of patients and a midline incision was used in the rest. Estimated blood loss was 1505 +/-103 mL; cell saver blood returned 754 +/-53 mL; crystalloid/Hespan 4771 +/-176 mL; banked packed red blood cells 0.75 +/-0.11 U. Time to extubation was, in the operating room (78.5%), on the day of the operation (5.0%), postoperative day (POD) 1 (12.4%), POD2 (1.7%), POD3 (0.8%), and one case was performed with epidural anesthesia only. Postoperative end points included a 30-day mortality rate of 1.6% (two patients). Postoperative morbidity included wound dehiscence 0.8%; sepsis, urinary tract infection, wound infection, leg ischemia, ischemic colitis, and stroke each had an incidence of 1.6%; myocardial infarction, congestive heart failure, pneumonia, re-operation for suspected bleeding, and ileus or bowel obstruction occurred with an incidence of 3.3%. No significant increase in serum creatinine levels was noted. Time to enteral fluids/nutrition was 3.5 +/-0.08 days. Patients were out of bed to a chair or walking by 1.3 +/-0.06 days postoperatively. The length of stay in the intensive care unit (ICU) was 2.0 +/-0.12 days and postoperative hospital stay was 6.6 +/- 0.33 days. Transfusion requirement for the hospital stay was 1.6 +/-0.2 U per patient. This review highlights a cohort of male veteran patients with significant cardiac co-morbidity who have undergone repair with a conventional open technique and low mortality and morbidity rates. This group had rapid extubation, time to oral intake, and ambulation. In addition, ICU and hospital stays were relatively short.

Folate supplementation inhibits intimal hyperplasia induced by a high-homocysteine diet in a rat carotid endarterectomy model

OBJECTIVE

Hyperhomocysteinemia has been implicated as a causative factor in intimal hyperplasia development. The addition of dietary folate in a hyperhomocysteinemia, carotid endarterectomy rat model is postulated to decrease plasma homocysteine levels and, in turn, reduce post-carotid endarterectomy intimal hyperplasia.

METHODS

Each rat was fed one of six diets: (1) lab chow with no folate (n = 7), (2) lab chow with 10 mg/kg folate added (n = 3), (3) lab chow with 25 mg/kg folate added (n = 3), (4) a homocysteine diet with no folate (n = 7), (5) a homocysteine diet with 10 mg/kg folate added (n = 5), or (6) homocysteine diet with 25 mg/kg folate added (n = 5). Each rat then underwent an open carotid endarterectomy. In 2 weeks, intimal hyperplasia in the carotid artery was measured. Plasma homocysteine and folate levels were measured.

RESULTS

Plasma folate levels rose with folate administration. Plasma homocysteine in the lab chow group was 5.4 +/- 0.5 micromol/L and did not change with the addition of folate. In the homocysteine diet group, plasma homocysteine rose 10-fold over the lab chow group (51.9 +/- 6.5 vs 5.4 +/- 0.5, micromol/L, P <.0001). In the group fed a homocysteine diet with 10 mg/kg folate added, a significant decrease in plasma homocysteine was observed (17.5 +/- 8.5 vs 51.9 +/- 6.5, micromol/L, P =.0003). In the group fed a homocysteine diet with 25 mg/kg folate added, plasma homocysteine levels were further reduced to levels seen in the lab chow group (12.6 +/- 2.6 vs 5.4 +/- 0.5, micromol/L, P = not significant). The relationship between plasma folate and homocysteine was inverse (R = 0.39, P =.0036). Luminal stenosis due to intimal hyperplasia was minimal in lab chow groups and unaffected by folate. The homocysteine diet group demonstrated post-carotid endarterectomy luminal stenosis due to intimal hyperplasia (60.9% +/- 9.2%). In the group fed a homocysteine diet with 10 mg/kg folate added, intimal hyperplasia was reduced, compared with the homocysteine diet group (32.6% +/- 7.4% vs 60.9% +/- 9.2%, P =.009). In the group fed a homocysteine diet with 25 mg/kg folate added, intimal hyperplasia was reduced to lab chow group levels (10.8% +/- 0.8% vs 4.8% +/- 1.0%, P = not significant) and was reduced, compared with the group fed a homocysteine diet with 10 mg/kg folate added.

CONCLUSION

The use of folate in this hyperhomocysteinemia carotid endarterectomy model and the resultant attenuation of plasma homocysteine elevation and intimal hyperplasia development lend strong support to homocysteine being an independent etiologic factor in post-carotid endarterectomy intimal hyperplasia.

Increased intimal hyperplasia after carotid endarterectomy in spontaneously hypertensive rats

This study evaluated the effects of hypertension on postoperative intimal hyperplasia using a rat carotid endarterectomy (CEA) model with spontaneously hypertensive rats (SHR) and normotensive Sprague-Dawley rats (SD). SHR and SD rats underwent left carotid exposure and CEA via an arteriotomy, scoring and removal of the intima, followed by arteriotomy closure. The rats were then sacrificed two weeks postoperatively. The left carotid artery was harvested and underwent elastin and double immunohistochemical staining. The percent of lumenal stenosis was calculated using morphometric measurements, and stained cells within the intimal hyperplasia were counted. The means and standard deviation of the means were calculated, and the two groups were compared using a 2-sample t test. The systolic blood pressure was 228 +/-35 mm Hg in the SHR group and 108 +/-8 mm Hg in the SD group (p<0.00001). The percent of lumenal stenosis was 82.6 +/-17.1% in the SHR group and 21.2 +/-13.7% in the SD rats (p value <0.0001). The percentage of cells staining for a-SM actin was equal in the SHR group and the SD group (> 91%) but the percentage of these cells staining for BrdU was 38.2 +/-8.4% in the SHR group and 10.7 +/-5.8% in the SD group (p< 0.00001). Hypertension in the SHR rats was associated with an increased lumenal stenosis due to increased intimal hyperplasia. The increased intimal hyperplasia was due to enhanced and accelerated replication of smooth muscle cells. Hypertension may be associated with increased restenosis rates after CEA.

Blue toe syndrome: treatment with intra-arterial stents and review of therapies

PURPOSE

To determine if intra-arterial stent placement can adequately treat lesions producing microemboli to the lower extremities.

MATERIALS AND METHODS

During a 6.5-year period, 15 patients presenting with blue toe syndrome had 16 presumed embolic lesions treated with intra-arterial stents. These patients were evaluated during routine clinical follow-up during a 6-month period. This evaluation included physical and noninvasive arterial examinations. When patients could not return for follow-up, hospital, clinical, vascular laboratory, and radiology records were reviewed to assemble the appropriate information. Outcomes included symptoms of recurrent emboli, amputation, and death.

RESULTS

Treated embolic lesions included two aortic stenoses, three bilateral iliac artery stenoses, nine unilateral iliac artery stenoses (one patient received separate treatment of unilateral iliac lesions), and two superficial femoral artery stenoses. Patients were followed-up for a mean of 18 months. Eight of 15 patients (53%) were improved or stable without complications. There were eight negative outcomes experienced in seven patients. Three patients (20%) were deceased at follow-up. Four patients (27%) had undergone amputation; one transmetatarsal amputation and three below-the-knee amputations. Only one of these was related to progressive disease in the treated extremity (7%). One patient (7%) experienced recurrent embolic symptoms. Stents were patent in all patients.

CONCLUSION

Patients with blue toe syndrome are at high risk of limb loss and mortality despite treatment. Intra-arterial stent placement provides an alternative to standard surgical treatment. Further studies are needed to define the optimum therapy.

Hyperhomocysteinemia increases intimal hyperplasia in a rat carotid endarterectomy model

PURPOSE

This preliminary study investigated the ability to elevate the serum homocysteine (H[e]) levels and investigated the increases in postoperative neointimal hyperplasia (IH) in an environment with hyperhomocysteinemia and the resultant restenosis in a rat carotid endarterectomy (CEA) model.

METHOD

The 9 rats for the control group were fed rat chow, and the 8 rats for the H(e) group were fed H(e)-supplemented rat chow for 2 weeks before and after CEA. The animals underwent anesthesia, and a left common CEA was performed. After 14 days, the serum H(e) levels were measured and the left carotid artery was harvested and elastin stained. Morphometric measurements were used to calculate the area of stenosis of the lumen. The mean and the standard deviation of the mean were determined. The 2 groups were compared with the Mann-Whitney test and a linear regression model. Three additional rats per group were studied, with carotid artery sectioning with double immunohistochemical staining for 5-bromodeoxyuridine (BrdU) and alpha-smooth muscle (alpha-SM) actin.

RESULTS

The serum H(e) level in the H(e) group was 36.32 micromol/L +/- 15.28, and in the control group the level was 5.53 micromol/L +/- 2.06 (P =.0007). IH presented as percent lumen stenosis was 21.89% +/- 4.82% in the H(e) group and 4.82% +/- 1.64% in the control group (P =.0007). The linear regression model of the serum H(e) levels and the percent stenosis showed a linear relationship (r2 =.72). The alpha-SM actin staining revealed that nearly all of the cells in the IH area were of smooth muscle or myofibroblast origin and that 10.1% +/- 2.6% of the cells were stained for BrdU in the control group versus 23% +/- 7.1% in the H(e) group. Also, 9.3% +/- 2.6% of the cells in the IH area were stained for BrdU and for alpha-SM actin versus 19.1% +/- 5. 6% stained for both BrdU and alpha-SM actin in the H(e) group.

CONCLUSION

This is the first study to examine IH after CEA and hyperhomocysteinemia in rats. The study shows that the elevation of serum H(e) levels can be obtained by feeding rats modified diets with added H(e). The consistent elevation of serum H(e) levels was associated with more than 4 times the amount of IH after a CEA in a rat model.

Assessment of apparent vena caval penetration by the Greenfield filter

PURPOSE

To examine and elucidate the mechanisms for apparent "penetration" by Greenfield vena caval filters.

METHODS

Two filters were placed in the inferior venae cavae (IVC) of four immature sheep and followed with cavography for 1 year. Two animals underwent computed tomography (CT) and laparoscopic examination. At necropsy, the vena cava and adjacent structures of all four animals were examined grossly and histologically.

RESULTS

Based upon cavography and CT imaging, all filters appeared to penetrate the vena cava at 12 months. However, at laparoscopy, no hooks or limbs were exposed, and the pericaval tissues remained intact; each hook or limb was within the adventitia or encapsulated in scar tissue. Histology of the tissue at the hook sites revealed remodeling of the intimal surface of the IVC and thinning of the adventitia.

CONCLUSIONS

Based upon these data, we hypothesize that the vena cava gradually adapts by medial and adventitial thinning and myointimal remodeling to the radial force exerted by a filter. This process allows increase in the filter base diameter while maintaining the integrity of the cava and protecting adjacent structures.

Azotemia: gadopentetate dimeglumine as contrast agent at digital subtraction angiography

In an azotemic patient with suspected renal artery stenosis, undiluted gadopentetate dimeglumine was administered in an aortic bolus to provide contrast at digital subtraction angiography of the aorta and renal arteries. The contrast material (5 mmol/mL) was power injected (rate, 15 mL/sec; total dose, 30 mL). Selective renal arteriography was also performed with 5 mL of undiluted gadopentetate dimeglumine hand injected into each renal artery (total dose, 40 mL). The patient tolerated the procedure without complication or worsening of renal function, and diagnostic angiographic images were obtained.