Iliac Artery Endoconduits Should be the Preferred Adjunctive Access Procedure to Facilitate Complex Endovascular Aortic Aneurysm Repair

BACKGROUND

Iliac artery anatomy can have a dramatic impact on the success of endovascular complex aortic aneurysm (CAA) procedures as endograft delivery systems need to be advanced and manipulated through these access vessels. The aim of this study was to evaluate the outcomes of iliac artery conduits with emphasizes on open vs endovascular conduits performed to facilitate CAA endovascular repair.

METHODS

All patients who had open or endovascular iliac conduits prior to endovascular CAA repair to treat thoracoabdominal, juxtarenal, or suprarenal aneurysms at the University of Colorado Hospital from January 2009 through January 2019 were included. Patients who presented with symptomatic or ruptured aortic aneurysms were excluded. Outcomes of interest included postoperative complications and mortality in patients undergoing iliac conduits.

RESULTS

Twenty-seven patients with a total of 42 conduits were included in the study. The majority of patients (N = 15, 56%) were female and the average age was 72 ± 9 years. The calculated VQI cardiac index was .6% (range, .3%-.8%). Eighteen (43%) endovascular and 24 (57%) open iliac conduits were performed during the study period. Thirty (71%) conduits were performed in a staged fashion, while 12 (29%) were performed at the same time as endovascular CAA repair. The mean time between conduit and definitive aneurysm repair surgery was 130 ± 68 days in the endovascular and 107 ± 79 days in the open groups (P = .87). No aneurysm rupture occurred during the staging period in either group. The median follow-up for the entire cohort was 18 ± 22 months. The median length of hospital stay for patients undergoing endovascular and open ICs was 6 (ranging, 1-28 days) and 7 days (ranging, 3-18 days), respectively. Patients undergoing open conduits had significantly more complications than those undergoing endovascular conduit (endoconduit) creation. A total of 4 (15%) patients died within 30 days after aneurysm repair. Out of 23 survivors, 18 (78%) patients were discharged home, 4 (18%) patients were discharged to a skilled nursing facility, and 1 (4%) patient was discharged to an acute rehabilitation facility. No mortality difference based on type of conduit was found.

CONCLUSIONS

Overall complication rate associated with creation of open iliac artery conduits is not negligible. Endoconduits, which carry less morbidity than open conduits, are preferred as a first-line adjunctive access procedure to facilitate complex endovascular aortic aneurysm repair.

Critical Appraisal of the Contemporary Use of Atherectomy to Treat Femoral-Popliteal Atherosclerotic Disease

OBJECTIVE

Atherectomy has become increasingly used as an endovascular treatment of lower extremity atherosclerotic disease in the United States. Concerns and controversies about its indication and outcomes exist. The goal of this systematic review and meta-analysis was to investigate the outcomes and complications related to atherectomy to treat femoropopliteal atherosclerotic disease.

METHODS

A systematic review following the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was performed. Four major scientific repositories, MEDLINE, EMBASE, The Cochrane Library, and Thompson Web of Sciences were queried from their inception to April 5, 2020. Data was reviewed and entered in a dedicated dataset by the investigators. Outcomes included patency rates, clinical and hemodynamic improvement, and morbidity and mortality associated with atherectomy interventions.

RESULTS

Twenty-four studies encompassing 1900 patients met inclusion criteria for this study. 74.3% of patients presented with Rutherford class (RC) 1-3 and 25.7% presented with RC class 4-6. 1445 patients underwent atherectomy, and 455 patients were treated without atherectomy. Atherectomy patients underwent directional atherectomy (DA, n = 851), rotational atherectomy (RA, n = 851), laser atherectomy (LA, n = 201), and orbital atherectomy (OA, n = 78). The majority of patients additionally received adjunct treatments which were variable across studies and included a combination of stenting, balloon angioplasty (BA), or drug coated balloon (DCB) angioplasty. Technical success was achieved in 92.3% of cases. Distal embolization, vessel perforation, and dissection occurred in 3.4%, 1.9%, and 4% of cases respectively. Initial patency was 95.4% and at 12-month median follow up primary patency was 72.6%. ABI improved from pre-operative mean of 0.6 to post-operative mean of 0.84. Incidence of major amputation and mortality over the follow up period was 2.2% and 3.4% respectively.

CONCLUSIONS

This review of the published data suggests that femoropopliteal atherectomy can be completed safely while modestly improving ABIs and maintaining one-year patency in nearly three out of four patients; however, this is based on heterogeneous studies that skew generalizable conclusions about atherectomy's efficacy. Atherectomy places a high cost burden on the healthcare system and is utilized in the United States at a higher rate than in other countries. Our review of the literature does not demonstrate clear atherectomy superiority to alternatives that would warrant pervasive and increasing use of this costly technology. Future work should focus on developing high quality randomized controlled trials to determine specific patient and lesion characteristics in which atherectomy can add value.

Iliac Conduits for Endovascular Treatment of Aortic Pathologies: A Systematic Review and Meta-analysis

PURPOSE

The treatment of thoracoabdominal aortic aneurysm has largely shifted to endovascular techniques. However, severe iliofemoral arterial disease often presents a challenge during these interventions. As a result, iliac conduits have been introduced to facilitate aortic endovascular therapy. The goal of the current study was to gauge utilization and to analyze iliac artery conduit outcomes to facilitate endovascular therapy to treat aortic pathologies.

MATERIALS AND METHODS

A meta-analysis of 14 studies was conducted with the use of random effects modeling. The incidence of periprocedural adverse events was gauged based on iliac conduit vs nonconduit cases and planned vs unplanned iliac conduit placement. Outcomes of interest included length of hospital stay, morbidity and mortality associated to conduits, and all-cause mortality.

RESULTS

Iliac conduits, either open or endo-conduits, were utilized in 17% (95% CI: 9%-27%) of 16,855 cases, with technical successful rate of 94% (95% CI: 80%-100%). Periprocedural complications occurred in 32% (95% CI: 22%-42%) of the cases, with overall bleeding complication rate being 10% (95% CI: 5%-16%). Female patients, positive history for smoking, pulmonary disease, and peripheral artery disease at baseline were associated with more frequent utilization of iliac conduits. Conduit use was associated with longer hospitalization, higher periprocedural all-cause mortality (OR: 2.85; 95% CI: 1.75-4.64; p<0.001), and bleeding complication rate (OR: 2.38; 95% CI: 1.58-3.58; p<0.001). Sensitivity analysis among conduit cases showed that planned conduits were associated with fewer periprocedural complications compared to unplanned conduits (OR: 0.38; 95% CI: 0.20-0.73; p=0.004).

CONCLUSION

Iliac conduit placement is a feasible strategy, associated with high technical success to facilitate complex aortic endovascular repair. However, periprocedural adverse event rate, including bleeding complications is not negligible. All-cause mortality and morbidity rates among cases that require iliac conduits should be strongly considered during clinical decision making. High-quality comparative analyses between iliac conduit vs nonconduit cases and between several types of iliac conduit grafts aiming at facilitating endovascular aortic repair are still needed to determine the best strategy to address challenging iliac artery accesses.

A systematic review and meta-analysis of outcomes after acute limb ischemia in patients with cancer

BACKGROUND

Cancer results in a hypercoagulable state that is associated with both venous and arterial thromboses. However, little is known about the effects of acute limb ischemia (ALI) in this cohort of patients. In the present systematic review and meta-analysis, we analyzed the available clinical data on cancer and its association with ALI and evaluated the outcomes in these patients after a diagnosis of ALI.

METHODS

Three databases, including PubMed, EMBASE, and the Cochrane Library, were queried. Studies that met the inclusion criteria were included regardless of the publication year, language, sample size, or follow-up length. All the steps of the meta-analysis were conducted in accordance with the PRISMA (preferred reporting items for systematic reviews and meta-analyses) and MOOSE (meta-analysis of observational studies in epidemiology) guidelines.

RESULTS

Seven studies from 6222 references with a total of 2899 patients were included. Of the 2899 patients, 1195 (41%) had had a diagnosis of ALI before their cancer diagnosis, and 1704 (59%) had presented with ALI after a cancer diagnosis. Nearly three quarters of ALI events were among patients with cancer of the skin and soft tissue (19%), genitourinary (18%), lung (17%), and gastrointestinal (16%) systems. ALI recurrence was similar between the two groups, and major amputation was more likely in patients with a diagnosis of ALI after a cancer diagnosis (7.4% vs 4.6%; P < .01). The incidence of mortality at 1 year was significantly greater for patients with established cancer who had presented with ALI compared with the patients who had presented with ALI before a cancer diagnosis (50.6% vs 29.9%; P < .01). After adjusting for study variability using the random effects model, the mortality at 1 year for all patients was 52.3% (95% confidence interval, 37.7%-66.5%). No significant heterogeneity (P = .73) was found between the two groups of patients, which varied by the timing of the ALI diagnosis in relation to the cancer diagnosis.

CONCLUSIONS

The 1-year mortality after the development of ALI in patients with cancer was >50%. For patients presenting with ALI of unclear etiology, the presence of an underlying cancer should be considered.

Exercise Training and Revascularization in the Management of Symptomatic Peripheral Artery Disease

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In the management of symptomatic peripheral artery disease, aerobic exercise therapy and lower extremity revascularization are the mainstays of therapy.

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In this structured review, the most effective therapies, with 6 to 18 months of follow-up, indicated that exercise therapy and lower extremity revascularization each independently improve peak walking performance.

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The combination of therapies was superior to either therapy alone and may decrease the need for subsequent revascularization.

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Further research is needed to evaluate the long-term durability of these interventions, their impacts on subsequent invasive procedures, and predictors of response.

Exercise therapy and lower extremity revascularization both improve walking performance in symptomatic patients with peripheral artery disease. The combination of therapies provides greater benefit than either alone and may reduce the need for subsequent revascularization procedures, but further trials with longer follow-up are needed for the outcome of subsequent revascularization.

Sharp Recanalization with the Upstream GoBack Catheter for Chronic Occlusive Ilio-Caval Thrombosis

Recanalization of chronic iliofemoral deep vein thrombosis is indicated to reduce symptoms and improve quality of life. However, recanalization is dependent on the ability to cross chronic obstructions. We present a case of chronically thrombosed inferior vena cava and common iliac veins that failed conventional crossing techniques but were successfully recanalized using the recently approved Upstream GoBack Crossing Catheter.

The utilization of intravascular lithotripsy to facilitate transcarotid artery revascularization

Carotid artery disease and stroke account for the second cause of mortality in worldwide. Recently, transcarotid artery stenting (TCAR) has emerged as a treatment modality that carries a very low stroke rate. However, there are limitations to TCAR, such as heavily calcified plaques that might preclude optimal stent expansion. We describe a successful transcarotid artery stenting with flow reversal performed in an independent and active nonagenarian with focal, circumferentially calcified carotid artery plaque, for which intravascular lithotripsy was utilized.

Percutaneous Endovascular Repair of a Ruptured Extent III Thoracoabdominal Aortic Aneurysm with Bilateral Large Common Iliac Aneurysms and Aortocaval Fistula

Ruptured thoracoabdominal aneurysms (rTAAAs) are rare and carry a significant rate of morbidity and mortality. Aortocaval fistula secondary to rTAAA is even more infrequent. We describe an urgent and staged endovascular treatment of a ruptured extent III thoracoabdominal aortic aneurysm with an aortocaval fistula by performing vena cava stenting to treat aortocaval fistula as a damage control maneuver prior to transfer and subsequent TAAA repair with a physician-modified endograft at a quaternary level hospital.

Outcomes of Endovascular AAA Repair in Patients with Hostile Neck Anatomy Using Adjunctive Balloon-Expandable Stents

Hostile neck anatomy remains the predominant reason that patients are denied endovascular aneurysm repair (EVAR). We reviewed our experience of EVAR with use of prophylactic adjunctive proximal balloon-expandable stents in patients with hostile neck anatomy and adjunctive proximal balloon-expandable stents in patients with type I endoleaks. Of 140 patients who underwent EVAR between 2000 and 2004, we reviewed data for 19 patients in whom we used proximal balloon-expandable stents. By high-resolution computed tomography scan or angiography, hostile neck anatomy was classified as length <15 mm, neck diameters = 26 mm, circumferential thrombus at the proximal neck, angulated neck =60 degrees, and neck bulge or reverse taper necks. Patients were considered to have hostile anatomy if they met 1 or more of the above-cited criteria. All patients underwent AAA repair with commercially available endograft systems, Zenith (Cook, Bloomington, IN) and AneuRx (Medtronic/AVE, Minneapolis, MN). Balloon-expandable stents utilized included Cordis-Palmaz stents (17/19) and eV3 Max stents (2/19). Stents were deployed in the proximal graft with transrenal extension. AneuRx (18/19) and Zenith (1/19) endografts were used in all of the patients. Of the 19 patients, 15 had prophylactic stent placement for known hostile neck anatomy and 4 patients had stent placement for type I endoleak. Assisted primary technical success was achieved in all patients. Three patients had maldeployment of the endograft or proximal stent requiring additional endovascular interventions at the time of surgery. No endografts were deployed too low requiring stent placement. Procedure-related complications occurred in 2 of 19 patients. These included 1 operative death secondary to pneumonia and 1 patient who developed progressive renal failure. Short-term clinical success was achieved in 17 of 19 patients. Two patients required secondary interventions, 1 due to device migration with secondary conversion to open repair, and an endoleak, which, on angiogram, was a large type II endoleak successfully treated with coiling of the inferior mesenteric artery. One patient was observed to have a type II endoleak with no associated aneurysm enlargement. Short-term results suggest the use of prophylactic adjunctive balloon-expandable stents may decrease the incidence of secondary interventions related to hostile neck anatomy when used as an adjunctive measure with EVAR. Based on our experience, we feel EVAR may be offered to an expanded patient population with hostile neck anatomy with use of prophylactic balloon-expandable stents.

Stenting of femoropopliteal lesions using interwoven nitinol stents

OBJECTIVE

The Supera stent (Abbott Laboratories, Abbott Park, Ill) has a unique biomimetic design allowing axial and longitudinal flexibility and fracture resistance. The aim of this retrospective study was to assess the midterm patency of Supera stents used to treat patients with superficial femoral and popliteal arterial disease by a single practice.

METHODS

From April 2010 to December 2011, 53 patients and 59 limbs with symptomatic femoropopliteal lesions underwent angioplasty and stenting with the Supera stent. Five patients had no follow-up and were excluded. Demographics of the patients, radiographic images, morphologic features of the lesions, procedural reports, reinterventions, and follow-up clinical visit notes were reviewed. Primary patency was defined as clinical resolution of symptoms with no secondary interventions. Primary and secondary patency rates at 12, 24, and 36 months were estimated by Kaplan-Meier analysis.

RESULTS

A total of 48 patients (42 men, six women; 54 limbs; mean age, 64.3 years [range, 51-87]) received Supera stents and had at least one follow-up visit as part of their treatment for femoropopliteal disease. Primary indications for intervention included claudication, rest pain, and tissue loss, at rates of 54% (29 of 54), 26% (14 of 54), and 20% (11 of 54), respectively; 22% of lesions were TransAtlantic Inter-Society Consensus type A or B and 78% were type C or D. Mean lesion length was 24.0 cm (range, 3-51). Mean follow-up was 27.5 months (range, 1-45). The ankle-brachial index increased from 0.58 ± 0.20 preoperatively to 0.77 ± 0.18 postoperatively (P = .00004). Primary, primary assisted, and secondary patency rates at latest follow-up were 79.6%, 88.9%, and 92.3%, respectively. Cumulative primary patency rates by Kaplan-Meier analysis at 12, 24, and 36 months were 85.6%, 83.1%, and 76.7%, respectively. Secondary patency rates by Kaplan-Meier estimates at 12, 24, and 36 months were 93.8%, 93.8%, and 89.3%, respectively. No stent fractures were found at the time of any reinterventions. Long lesions >30 cm (n = 18) showed equivalent patency to lesions of 1 to 15 cm (n = 18) and lesions 15 to 30 cm in length (n = 18).

CONCLUSIONS

Our midterm results show that Supera stents are durable in treating femoropopliteal lesions, with notably high patency rates in patients with long lesion lengths.

Endovascular repair of a para-anastomotic pseudoaneurysm after renal autotransplantation: an alternative to open reconstruction

Renal artery anastomotic pseudoaneurysms are rare after renal transplantation. The etiology tends to be technical, infectious, or degenerative, and repair is difficult with a high postsurgical complication rate. We report the first case of a complex autotransplant renal artery pseudoaneurysm repaired with kissing covered stents. A 52-year-old woman presented with severe left lower quadrant abdominal pain 6 years after a renal autotransplant for ureteral stenosis and recurrent pyelonephritis. A computed tomographic angiography (CTA) scan revealed a bilobed aneurysm arising at the anastomosis between the renal and common iliac arteries. Kissing covered stents were placed within the common iliac artery proximally and extending into the transplant renal artery and external iliac artery. Postdeployment angiography confirmed complete exclusion of the pseudoaneurysm and excellent flow into the transplant kidney and left lower extremity. A follow-up CTA scan at 1 month revealed continued stent-graft patency and complete exclusion of the pseudoaneurysm. An endovascular approach to transplant anastomotic pseduoaneurysms using kissing covered stents is a viable option to exclude aneurysmal changes and preserve flow to the transplanted organ in carefully selected patients.

Treatment of chronic venous stent occlusion with a Wildcat catheter

A 47-year-old female with an occluded iliac vein stent originally placed for deep venous thrombosis and May-Thurner syndrome presented to our clinic with complaints of left lower extremity pain and swelling. Multiple previous attempts had been made to cross this lesion with guidewire and catheter techniques without success. We were able to cross the lesion with the Wildcat catheter. Subsequent directional laser atherectomy and balloon angioplasty followed by stent placement resulted in a patent stent and resolution of her symptoms. This is the first reported use of the Wildcat catheter in chronic venous stent occlusions.

AMP-activated protein kinase response to contractions and treatment with the AMPK activator AICAR in young adult and old skeletal muscle

One characteristic of ageing skeletal muscle is a decline in mitochondrial function. Activation of AMP-activated protein kinase (AMPK) occurs in response to an increased AMP/ATP ratio, which is one potential result of mitochondrial dysfunction. We have previously observed higher AMPK activity in old (O; 30 months) vs young adult (YA; 8 months) fast-twitch muscle in response to chronic overload. Here we tested the hypothesis that AMPK would also be hyperactivated in O vs YA fast-twitch extensor digitorum longus muscles from Fischer(344) x Brown Norway (FBN) rats (n = 8 per group) in response to high-frequency electrical stimulation of the sciatic nerve (HFES) or injection of AICAR, an activator of AMPK. Muscles were harvested immediately after HFES (10 sets of six 3-s contractions, 10 s rest between contractions, 1 min rest between sets) or 1 h after AICAR injection (1 mg (g body weight)(-1) subcutaneously). The phosphorylations of AMPKalpha and acetyl-CoA carboxylase (ACC2; a downstream AMPK target) were both greatly increased (P <or= 0.05) in response to HFES in O muscles, but were either unresponsive (AMPK alpha) or much less responsive (ACC) in YA muscles. AMPK alpha2 activity was also greatly elevated in response to HFES in O muscles (but not YA muscles) despite a lower total AMPK alpha2 protein content in O vs YA muscles. In contrast, AMPK alpha2 activity was equally responsive to AICAR treatment in both age groups. Since mitochondrial content and/or efficiency could potentially underlie AMPK hyperactivation, we measured levels of mitochondrial proteins as well as citrate synthase (CS) activity. While CS activity was increased by 25% in O vs YA muscles, uncoupling protein-3 (UCP-3) protein level was upregulated with age by 353%. Thus, AMPK hyperactivation in response to contractile activity in aged fast-twitch muscle may be the result of compromised cellular energetics and not necessarily due to an inherent defect in responsiveness of the AMPK molecule per se.

Bedside vena cava filter placement with intravascular ultrasound: a simple, accurate, single venous access method

Two techniques of vena cava filter placement with intravascular ultrasound (IVUS) guidance have been described previously. Placement with real-time IVUS imaging requires two venous access sites, one for the filter delivery system and one for the IVUS catheter, which makes the procedure more invasive. Alternatively, a single-access technique of IVUS imaging of the vena cava requires measuring the distance from the access site to the desired location for filter placement and then delivering the filter to that distance blindly, risking filter misplacement. We describe in this article a single puncture technique that allows for real-time imaging to position the filter delivery sheath using IVUS and reduces the uncertainty of the blind positioning of the filter delivery system.

True lumen re-entry devices facilitate subintimal angioplasty and stenting of total chronic occlusions: Initial report

OBJECTIVE

The acute technical failure of endovascular treatment of chronic total occlusions (CTOs) is most often due to the inability to re-enter the true lumen after occlusion is crossed in a subintimal plane. This study reports our initial experience with true lumen re-entry devices in the treatment of CTOs.

METHODS

Patients with treatment of CTOs were identified from our vascular registry. All patients in whom the Pioneer catheter or the Outback catheter were used were also identified from a prospectively maintained separate database of cases in which true lumen re-entry devices were used. We used procedural data from the prospective database and reviewed the medical records. Lesion character and location, access type, location of true lumen re-entry, stent usage, procedural times, and complications, were tabulated.

RESULTS

From August 2003 to December 2004, endovascular techniques were used to treat 87 CTOs in 58 iliac and 29 superficial femoral arteries. In 24 (26%), the true lumen could not be re-entered by using standard catheter and wire techniques. The true lumen was not initially re-entered in 20 (34%) of 58 of treated iliac CTOs and four (13%) of 29 of treated superficial femoral artery CTOs (73% TASC C and D lesions). Intravascular ultrasound-guided true lumen re-entry using the Pioneer catheter (21 CTOs), or fluoroscopic-guided true lumen re-entry using the Outback catheter (3 CTOs) was successful in achieving true lumen re-entry in all cases at the location desired. Total time of re-entry catheter manipulation required to achieve re-entry was <10 minutes and was routinely accomplished in <3 minutes. All occlusions were stented. No cases were converted to open repair. Bleeding from the recanalization and angioplasty site occurred in four patients (15%). It was controlled with use of covered stents in two cases, and resolved after placement of uncovered stents in the other two. No significant bleeding occurred at the sites of true lumen re-entry needle deployment. All occlusions treated with true lumen re-entry devices remain clinically patent at a mean follow-up of 5.8 months.

CONCLUSIONS

Endovascular treatment of chronic total occlusions is often limited by the inability to re-enter the true lumen after subintimal crossing of the occluded segment. This occurs more commonly with treatment of iliac occlusions than in superficial femoral artery occlusions. True lumen re-entry catheters are very effective at gaining wire passage back to the true lumen and facilitating successful endovascular treatment of chronic total occlusions that would otherwise require open bypass.

Crossing Chronic Total Occlusions of the Iliac and Femoral-Popliteal Vessels and the Use of True Lumen Reentry Devices

Treatment of chronic total occlusions of the iliac and femoral-popliteal vessels with endovascular techniques has become the standard approach for shorter lesions and is increasingly applied to long, complex arterial occlusive lesions. As the complexity of the arterial occlusions increases, the demands for technical skills and devices needed to successfully cross and treat the occlusion also increases. We describe here our technique for treatment of iliac and femoral-popliteal occlusions. Important aspects of that that have allowed for a high technical success include (1) the use of hydrophilic wires and catheters to traverse occlusions in the subintimal plane, (2) femoral access with axially supported catheters or sheaths to apply the force needed for successful recanalization, and (3) the use of true lumen reentry devices when, after crossing the occlusion, the wire or catheter cannot be manipulated into the true lumen beyond the occlusion.

Ischemic colitis: spectrum of disease and outcome

BACKGROUND

The aim of this study was to identify risk factors, clinical characteristics, and outcome of patients with colon ischemia.

METHODS

A 10-year (1992-2002) retrospective study was undertaken. Patients were identified from computerized hospital discharge information. Patient variables were entered into a computerized database and analyzed.

RESULTS

One hundred twenty-nine patients were identified. The mean age was 66 years (range, 29-98 years); 47% were male. Forty-three patients (33%) had chronic renal failure; 73 patients (57%) were receiving vasoactive drugs, and 72 patients (56%) had atherosclerosis. Fifty-four of 129 patients (42%) had ischemic colitis in-hospital. Fifty-six of 129 patients (43%) had melena; 49 of 56 patients (88%) survived. Forty-three of 129 patients (33%) had an acute abdomen; 22 of 43 patients (51%) died. Seventy of 129 patients (54%) were treated nonoperatively initially; the condition of 17 of 70 patients (24%) required surgery. Of 76 patients who were treated operatively, 31 patients (41%) died. Eleven patients at operation had ischemia without colon infarction or perforation; 5 of these patients (45%) died. The overall mortality rate was 29% (37/129 patients).

CONCLUSION

Ischemic colitis is associated with chronic renal failure and atherosclerosis. Patients commonly have an acute abdomen. The absence of colonic infarction does not ensure a favorable outcome. Patients who are felt to be candidates for nonoperative therapy have significant mortality rates. Mortality rates remain high, despite treatment.

Analysis of various nucleosides in plasma using solid phase extraction and high-performance liquid chromatography with UV detection

The National Cancer Institute (NCI) has screened many nucleosides for antiviral activity to the HIV-1 virus. Drugs demonstrating antiviral activity are tested in animal models to evaluate their toxicity and pharmacokinetic characteristics. These drugs are subsequently evaluated for efficacy in human clinical trials. Sensitive analytical methodology is needed to quantify nucleosides in plasma and other biological matrices in support of these studies. Battelle has modified and validated a reversed phase high-performance liquid chromatography (HPLC) method for several of these nucleosides that could be easily adapted for similar compounds. Methods have been validated for 6-chloro-2',3'-dideoxyguanosine (6ClddG), 6-chloro-2',3'-dideoxyinosine (6ClddI) and their primary metabolites 2',3'-dideoxyguanosine (ddG) and 2',3'-dideoxyinosine (ddI) in both rat and dog plasma containing EDTA. The method has also been validated for 2'-fluoro-2',3'-dideoxyara-adenosine (betaFlddA) and its primary metabolite 2'-beta-fluorodideoxyinosine (betaFddI) in rat plasma containing heparin. Calibration plasma standards were prepared over ranges of 0.1-10 microg ml(-1) for betaFlddA and betaFddI, 0.1-50 microg ml(-1) for 6ClddG and ddG, and 0.25-50 microg ml(-1) for 6ClddI and ddI in plasma containing 4 microg ml(-1) pentostatin. The addition of pentostatin to the plasma samples inhibits in-vitro deamination of the drug after collection. Quality control (QC) standards were prepared containing the appropriate anticoagulant and 4 microg ml(-1) pentostatin at concentrations within each of the bracketed calibration ranges in plasma. These methods have been successfully applied to plasma samples generated during various animal studies.

Hypoxia-reoxygenation potentiates zymosan activated plasma-induced endothelial injury

The pathophysiology of ischemia-reperfusion injury and the role played by the interaction of plasma proteins, including complement, with reperfused endothelium remains incompletely understood. Venular endothelial changes due to hypoxia followed by reoxygenation (H-R) are vital because venules are the primary site of fluid accumulation and polymorphonuclear leukocyte deposition due to inflammation. This investigation focused on whether H-R potentiates the response to permeability inducing agents found in activated plasma. Activated complement was studied by using zymosan activated plasma (ZAP). Permeability changes were assessed by quantitating rate of clearance of albumin across the monolayers. H-R alone did not change permeability relative to the normoxic condition. ZAP at 2% in normoxic cells increased albumin clearance from 2 +/- 0.2 to 9 +/- 1. 0 microL/h, which increased significantly to 13.5 +/- 2.0 microL/h when given to hypoxia-reoxygenation challenged monolayers. The permeability response to ZAP was dose related and not present with heat inactivated ZAP. ZAP at 2% altered the structure of the cytoskeleton of the human umbilical vein endothelial cells (HUVEC). However, addition of monoclonal anti-complement antibodies or addition of soluble complement receptor-1 did not attenuate ZAP-induced HUVEC permeability. Addition of zymosan-activated serum did not alter the permeability and addition of heparin inhibited the ZAP-induced changes in permeability, suggesting that these changes were mediated via thrombin and not complement. The increase in monolayer permeability due to ZAP was prevented by increasing intracellular adenosine-3',5'-cyclic monophosphate. These findings suggest that HUVEC monolayers challenged with H-R are more susceptible to increases in permeability induced by activated plasma components.

Outcome of abdominal aortic aneurysm repair in patients with previous spinal cord injury in the Department of Veterans' Affairs hospitals

A retrospective review was carried out to determine the morbidity and mortality of abdominal aortic aneurysm repair in patients with previous spinal cord injury. A population-based study utilizing computer records on all patients in Department of Veterans' Affairs medical centers from 1987-1991 identified 31 patients with spinal cord injury who underwent subsequent infrarenal abdominal aortic aneurysm repair. Additional information was obtained from individual medical records. Some twenty patients (65%) were paraplegics and 11 (35%) were quadriplegics. Aneurysms were most commonly discovered incidentally during work-up of other conditions. All patients had no symptoms referable to their abdominal aortic aneurysm. In total, 29 patients (94%) underwent elective operations. The complication rate (57%) involved mostly pulmonary, cutaneous or urinary tract morbidity. The 30-day mortality rate was 3% for elective abdominal aortic aneurysm repair. Two patients were operated upon as emergencies for rupture, with one operative death. Long-term follow-up revealed a median survival duration of 5.4 years after aneurysm repair. In conclusion, abdominal aortic aneurysm repair in patients with previous spinal cord injury has a low mortality rate. Postoperative complications are often related to spinal cord injury and are potentially preventable; thus, such injury should not preclude surgical intervention for abdominal aortic aneurysm.

Ischemic colitis complicating abdominal aortic aneurysm surgery in the U.S. veteran

Ischemic colitis (IC) is an infrequent but serious complication of abdominal aortic surgery. Prior reports have generally described small, selected populations. The aim of this paper is to evaluate characteristics of clinically diagnosed IC in a large non-referral-based population. Using national Veterans Affairs (VA) computer data sets, we identified all patients with the diagnostic codes for both prosthetic replacement of aorta for abdominal aortic aneurysm and subsequent vascular insufficiency of the intestine in the entire VA population from 1987 to 1991. Clinical information on these patients was then requested from the VA Medical Centers where they received care. Patients demographics, clinical data regarding both the aortic surgery and IC, and survival data were extracted from patient charts and computer records. Of 4957 patients who underwent surgery of the abdominal aorta for infrarenal abdominal aortic aneurysm, 58 (1.2%) also had the code for subsequent IC. In 49/58 (74%), sufficient chart-derived and computer-derived data were available for analysis. The mean age was 69 (range 57-95); all were males. Bloody diarrhea was the most frequent symptom and colonoscopy the most common means of diagnosis. Mean time to diagnosis of IC was 5.5 days after aortic surgery (range 1-21 days). Aneurysmal rupture or perioperative hypotension were present in 35/49 patients. Bowel resection with fecal diversion was required in 32/49 (65%). The overall mortality was 54% but it was 89% if bowel resection for bowel infarction was required. Only 2/12 (16%) of those who required fecal diversion and survived underwent eventual stoma closure. Among 7 patients who received second-look laparotomy for IC, additional bowel resection was required in 6. No patient had aortic graft infection diagnosed during the index hospitalization. The overall mean hospitalization duration after the diagnosis of IC was 38 days (range 1-164). IC following aortic aneurysm surgery in this national patient population is infrequently diagnosed. Emergency aneurysm operation and perioperative hypotension are common in patients who develop IC. The majority of patients diagnosed receive surgical intervention. Most patients who undergo fecal diversion retain their stomas.

Acute aortic dissection into a preexisting abdominal aortic aneurysm

Acute aortic dissection and abdominal aortic aneurysm presenting as coexistent conditions is rare. We report a patient with a history of hypertension and acute severe back pain who had an acute aortic dissection extending into a preexisting 8 cm abdominal aortic aneurysm that was diagnosed by CT scan. There was no evidence of aortic rupture or leakage. The patient was treated with antihypertensive medication for 2 months to allow maturation of the acute dissection prior to elective repair of the abdominal aortic aneurysm. The repair was constructed to allow continued perfusion of both the true and false lumina by fenestration of the aortic septum at the proximal anastomosis. There were no postoperative complications. This case illustrates an unusual combination of aortic diseases. A management plan is described that safely treats both pathologic conditions.

Epithelioid sarcoma in childhood: An immunohistochemical, electron microscopic, and clinicopathologic study of 11 cases under 15 years of age and review of the literature

Epithelioid sarcoma in a rare tumor and most of the cases occur in young adults. It is rare in childhood. We have been able to obtain data and histologic material for 11 patients with this disease. The primary sites were head and neck in three patients, inguinal region in one, and extremities in seven. The age range of the patients was 12 weeks to 13 years. There was a preponderance of males over females with a ratio of 1.75. The tumors presented with a typical nodular necrotizing pattern. In three cases giant osteoclast-like cells were present. The immunohistochemistry and electron microscopy showed features consistent with previous observations on epithelioid sarcomas. In one case islands of small dark cells noted on light microscopy were surrounded by basal lamina on electron microscopy. The cells inside the nests were undifferentiated. Six tumors studied by flow cytometry were in DNA diploid range. On follow-up, five children are alive and well 2 to 7 years after treatment. Three children died of tumor progression with metastases to lymph nodes and lungs. One child had been diagnosed only recently, and in one the disease has run a protractive course with multiple recurrences. The behavior of these epithelioid sarcomas in children is similar to that seen in adults, the prognosis being dependent on radical tumor surgery preventing recurrent disease. Long-term follow-up is necessary because the tumor may recur many years after the primary tumor was removed.

Childhood rhabdomyosarcoma with anaplastic (pleomorphic) features. A report of the Intergroup Rhabdomyosarcoma Study

The pleomorphic subtype of rhabdomyosarcoma (RMS) is now rarely diagnosed in both children and adults. Most cases previously called pleomorphic RMS are probably diagnosed as something else, most often embryonal RMS in children and malignant fibrous histiocytoma in adults. To analyze the concept of pleomorphic RMS in children, we reviewed the tumors of patients entered on the Inter-group Rhabdomyosarcoma Study (IRS I, II, and III). The presence of cells with lobated, hyperchromatic nuclei at least three times larger than the common tumor cell population (anaplastic cells) was selected as the main criterion. Of about 3,000 cases, 110 showed these types of cells, had sufficient histologic material, and had available follow-up data. These tumors were divided into two subgroups: Subgroup I tumors contained only scattered anaplastic cells, and tumors with foci or large sheets of anaplastic cells were classified as subgroup II. Besides the anaplastic-pleomorphic areas, most of these tumors had distinctive features of embryonal RMS (105 cases) and rarely had characteristics of alveolar RMS (five cases). The age distribution of these patients did not differ significantly from those whose tumors did not show the anaplastic features, the average being 6 years and the median 4 years. Lower extremity, retroperitoneum, and the head and neck region were the most common primary tumor sites. The 5-year survival rate was 60% for subgroup I tumors and 45% for subgroup II tumors compared with the survival rate of 68% for 482 IRS II embryonal RMS cases with no anaplastic-pleomorphic features. The lower survival rate for patients in subgroup II was statistically significant (p = 0.004) and similar to the unfavorable survival of patients with alveolar RMS and undifferentiated sarcoma. Because anaplastic cells are seen in many soft tissue sarcomas and in both embryonal and alveolar RMS in children, this feature is not sufficiently unusual to separate a pleomorphic subtype of RMS. The presence of anaplastic cells in aggregates or diffuse sheets throughout the tumor, however, portends a poor survival for these patients.

Gastric compliance and motility in the portal hypertensive rat

In an ex vivo rat model, we compared the intraluminal pressure response of both the whole stomach and the antrum to progressive intraluminal distension in portal hypertensive and sham-operated rats. In both groups, this response featured a biphasic change in tone with superimposed phasic pressure waves. While the tonic pressure response to distension (reflecting gastric compliance) was similar in both groups, the frequency and amplitude of antral phasic pressure waves (reflecting antral motility) were greater in the portal hypertensive animals. These studies indicate that portal hypertension does not alter gastric compliance but is associated with an exaggerated antral motor response to distension, suggesting that this latter mechanism, rather than impaired accommodation, may explain the accelerated gastric emptying described previously in the portal hypertensive rat.

Indications and results of shunt operations in the treatment of patients with recurrent variceal hemorrhage

None of the portasystemic shunts are ideal for all patients with recurrent variceal hemorrhage. Hemodynamic and clinical status should determine the type of shunt selected. Patients with a compatible anatomy, hepatopetal protal flow and controlled ascites are best served by a distal splenorenal shunt. Patients with variceal hemorrhage and medically resistant ascites are candidates for a side-to-side shunt, with consideration being given to an operation that avoids dissection of the porta hepatis. The end-to-side portacaval shunt should be used only in the emergency situation when other options are not available. However, due to the effectiveness of other therapies, such as sclerotherapy, in controlling bleeding, emergency shunts are rarely required. On the basis of the controlled trials of distal splenorenal shunt versus sclerotherapy, the latter is the initial treatment of choice with distal splenorenal shunt used promptly when sclerotherapy fails. Patients who live in remote areas, and noncompliant individuals may be best served with a distal splenorenal shunt as initial therapy.

The effect of mesenteric venous hypertension on gut motility and absorption

The effects of portal hypertension on gut function may be mediated by venous congestion and altered circulating levels of enteric hormones and neuropeptides. We designed this study to determine the effects of chronic intestinal venous hypertension (VHT), in isolation, on gut motility and absorption. In 10 dogs, a 20- to 25-cm loop of jejunum was isolated from the fecal stream, but myoneural continuity was maintained with the proximal bowel by a seromuscular bridge. In 5 dogs, VHT was created in the loop by a fixed stenosis of its venous drainage; a sham procedure was performed in a further 5 animals. Serosal monopolar electrodes were placed in all animals. Absorptive function and myoelectrical activity were studied over a 4-week period. Venous hypertension was achieved and sustained in the VHT animals; loop vein pressures for VHT vs control in cm H2O (means +/- SEM) are: initial--29.8 +/- 1.8 vs 7.5 +/- 0.4 (P less than 0.01), and at 4 weeks--17.6 +/- 6.88 vs 7.3 +/- 0.2 (P less than 0.01). Absorption of Na+, Cl-, glucose, and water was impaired in VHT loops. Normal patterns of fasting and postprandial myoelectrical activity were preserved in the VHT animals. We conclude that chronic VHT, in the absence of portosystemic shunting, results in impaired absorption of water, glucose, and electrolytes without any change in intestinal motility.

Redox reactions associated with iron release from mammalian ferritin

The early redox events involved in iron reduction and mobilization in mammalian ferritin have been investigated by several techniques. Sedimentation velocity measurements of ferritin samples with altered core sizes, prepared by partial reduction and Fe2+ chelation, suggest two different events occur during iron loss from the ferritin core. Reductive optical titrations confirm this biphasic behavior by showing that the first 20-30% of core reduction has different optical properties than the latter 70-80%. Proton uptake during initial core reduction is near zero, but as the percent core reduction increases, the proton uptake (H+/e) values increase to 2 H+/e (2 H+/Fe3+ reduced) as core reduction approaches 1 e/Fe3+. Coulometric reduction of ferritin by mediators of different redox potential and different cross-sectional areas show a two-phase sigmoidal reaction pattern in which initial core reduction occurs at a slower rate than later core reduction. The above experiments were all conducted in the absence of iron chelators so that the observed results were all attributed to core reduction rather than the combined effects of core reduction accompanied by Fe2+ chelation. The coulometric reduction of ferritin by various mediators shows a correlation more with reduction potential than with molecular cross-sectional area. The role of the ferritin channels in core reduction is considered in terms of the reported results.

Effects of enteral vs parenteral nutrition on reticuloendothelial function

Previous investigations have shown that animals maintained with enteral nutrition are better able to survive an intraperitoneal bacterial challenge than animals receiving parenteral nutrition. The aim of this study was to assess the effects of enteral and parenteral nutrition on reticuloendothelial function. Eighteen enteral-fed male Sprague-Dawley rats had access to a standard hyperalimentation solution via a sipper tube ad libitum. Seventeen parenteral-fed animals received the same solution at an infusion rate determined by the volume ingested by the pair-fed enteral animals. All animals had central venous catheters. After 12 days, reticuloendothelial function was assessed by measuring the clearance rate (K) and the organ distribution of intravenous 51Cr-labeled sheep red blood cells and by plasma fibronectin levels. Nutritional status was assessed by body weight and nitrogen balance. K values in enteral and parenteral animals were similar (0.110 +/- 0.011 and 0.140 +/- 0.012, respectively, mean +/- SEM) as were plasma fibronectin levels (196 +/- 22 and 228 +/- 15 micrograms, respectively). Organ distribution of the 51Cr-labeled sheep red blood cells was the same in both groups. Nitrogen balance and body weights were also similar in both groups. These data demonstrate that in this experimental model enteral nutrition and parenteral nutrition were equally effective at maintaining reticuloendothelial function and nutritional status.

The effect of the route of nutrient delivery on gut structure and diamine oxidase levels

Diamine oxidase (DAO) is an intestinal mucosal enzyme which serves as a marker of cellular maturity and integrity in ontogeny and after mucosal injury in the gastrointestinal tract. Since total parenteral nutrition is known to result in intestinal hypoplasia, this study was done to determine the effect of enteral and parenteral delivery of nutrients on gut structure and DAO levels. Central venous catheters were placed in 27 Sprague-Dawley rats (180-260 g), which received nutrients for 12 days via parenteral nutrition (GpI n = 10), oral intake of the parenteral solution (GpII n = 8), or standard rat chow (GpIII n = 9). Gross and microscopic measurements were made at sacrifice. Mucosal DAO levels were determined by metabolism of [3H] putrescine. Group III animals had a greater caloric intake than groups I and II, and were the only group with a significant increase in body weight. Gut weight, mucosal weight, and villous height were significantly less in group I vs groups II and III; group II values were less than group III (p less than 0.05). Both DAO specific activity and total gut DAO were significantly less in group I and group II. Mucosal DAO content correlated with total gut and mucosal weight. DAO mucosal levels decrease with parenteral nutrition, reflecting the intestinal hypoplasia that occurs. Mucosal DAO content may be dependent on both caloric intake and diet composition. Since serum DAO levels are known to correlate with mucosal DAO content, DAO activity may prove useful as a circulating marker of the effect of nutritional therapy on the intestinal mucosa.

Solubilization of the iron molybdenum cofactor of Azotobacter vinelandii nitrogenase in dimethylformamide and acetonitrile

The iron molybdenum cofactor of Azotobacter vinelandii nitrogenase has been solubilized for the first time in dimethylformamide and acetonitrile. These solutions have the ability to reconstitute the inactive nitrogenase of the UW 45 mutant of A. vinelandii and exhibit an S = 3/2 EPR signal similar to that for the cofactor in N-methylformamide. Our ability to obtain solutions of FeMoco in these solvents seemingly refutes a previous hypothesis concerning the necessity of solvents with a dissociable proton for iron molybdenum cofactor solubility and should facilitate the spectroscopic characterization of this important species.

An inhibitory effect of sulfhydryl compounds in the assay of rat and mouse thymic terminal deoxynucleotidyl transferase (TdT)

Terminal deoxynucleotidyl transferase (TdT) was assayed in 100,000 X g supernatants of homogenized thymus using 3H-dGTP and an oligo p(dA)12-18 primer. 2-Mercaptoethanol (2-ME) caused a depression of activity with rat and mouse thymus extracts but increased activity using bovine or lamb thymus extracts. Glutathione (GSH), L-cysteine and dithiothreitol (DTT) also showed an inhibitory effect with the rat thymus extract. Inhibition was significant at concentrations of sulfhydryl compounds commonly included in TdT assays (1 mM-2 mM).

In vivo and in vitro effects of 1,1-dimethylhydrazine on selected immune functions

The in vivo phase of the experiments reported here include the evaluation of immune function after short-or long-term treatment of mice with 1,1-dimethylhydrazine (UDMH). Long-term exposure (3 injections/week for 14 weeks) resulted in increased numbers of Jerne plaque-forming cells, a trend toward decreased induction of suppressor cell activity by concanavalin A (Con A), and no effects on mitogen-induced lymphocyte blast transformation (LBT), compared to saline-treated control mice. These effects were greatest at doses of 10 or 50 mg/kg, while higher doses had less of an effect. In vitro experiments were performed by adding UDMH to normal murine splenocytes in the LBT assay and con A-induced suppressor cell assay. The UDMH induced a significant enhanced response to lipopolysaccharide (LPS) at 10 and 50 micrograms/ml, and a suppressed response to both Con A and LPS at higher concentrations. The UDMH also caused a decrease in suppressor cell activity at 25 micrograms/ml. Selective abrogation of suppressor activity or alteration of the suppressor cell-helper ratio were suggested as possible mechanisms for the enhancement effect associated with UDMH.