Ideational factors associated with consistent use of insecticide-treated nets: a multi-country, multilevel analysis

BACKGROUND

Malaria remains a major cause of morbidity and mortality in sub-Saharan Africa. Using insecticide-treated nets (ITNs) every night, year-round is critical to maximize protection against malaria. This study describes sociodemographic, psychosocial, and household factors associated with consistent ITN use in Cameroon, Côte d'Ivoire and Sierra Leone.

METHODS

Cross-sectional household surveys employed similar sampling procedures, data collection tools, and methods in three countries. The survey sample was nationally representative in Côte d'Ivoire, representative of the North and Far North regions in Cameroon, and representative of Bo and Port Loko districts in Sierra Leone. Analysis used multilevel logistic regression and sociodemographic, ideational, and household independent variables among households with at least one ITN to identify correlates of consistent ITN use, defined as sleeping under an ITN every night the preceding week.

FINDINGS

Consistent ITN use in Côte d'Ivoire was 65.4%, 72.6% in Cameroon, and 77.1% in Sierra Leone. While several sociodemographic and ideational variables were correlated with consistent ITN use, these varied across countries. Multilevel logistic regression results showed perceived self-efficacy to use ITNs and positive attitudes towards ITN use were variables associated with consistent use in all three countries. The perception of ITN use as a community norm was positively linked with consistent use in Cameroon and Côte d'Ivoire but was not significant in Sierra Leone. Perceived vulnerability to malaria was positively linked with consistent use in Cameroon and Sierra Leone but negatively correlated with the outcome in Côte d'Ivoire. Household net sufficiency was strongly and positively associated with consistent use in all three countries. Finally, the findings revealed strong clustering at the household and enumeration area (EA) levels, suggesting similarities in net use among respondents of the same EA and in the same household.

CONCLUSIONS

There are similarities and differences in the variables associated with consistent ITN use across the three countries and several ideational variables are significant. The findings suggest that a social and behaviour change strategy based on the ideation model is relevant for increasing consistent ITN use and can inform specific strategies for each context. Finally, ensuring household net sufficiency is essential.

Malaria care-seeking and treatment ideation among gold miners in Guyana

Background

Although miners are a priority population in malaria elimination in Guyana, scant literature exists on the drivers of malaria-related behaviour. This study explores the relationship between gold miners’ malaria-related ideation and the adoption of malaria care-seeking and treatment behaviours including prompt care-seeking, malaria testing, and self-medication.

Methods

Data are from a cross-sectional quantitative survey of 1685 adult miners between the ages of 18–59 years who live in mining camps in Regions 1, 7, and 8. The analysis focused on miners who reported an episode of fever in the past year (n = 745). Malaria care-seeking and treatment ideation was defined as a composite additive score consisting of the following variables: general malaria knowledge, perceived severity, perceived susceptibility, beliefs, perceived self-efficacy, perceived norms, interpersonal communication, and perceived response efficacy. Multivariable logistic regressions explored the relationship between ideation on care-seeking/treatment behaviours, controlling for confounding variables.

Results

Most miners with a recent episode of fever had perceived risk (92%), self-efficacy (67%), susceptibility (53%) and high malaria knowledge (53%). Overall, miners' care-seeking/treatment ideation score ranged from 0 to 8 with a mean of 4.1. Ideation scores were associated with higher odds of care-seeking for fever (aOR: 1.19; 95% CI 1.04–1.36), getting tested for malaria (aOR: 1.22; 95% CI 1.07–1.38) and lower odds of self-medication (aOR: 0.87; 95% CI 0.77–0.99).

Conclusions

A national community case management initiative is using study findings as part of its scale-up, using volunteers to make testing and treatment services more accessible to miners. This is complemented by a multi-channel mass media campaign to improve miners’ ideation. Communication messages focus on increasing miners’ knowledge of malaria transmission and symptoms, encourage positive beliefs about malaria testing and volunteer testers, promote evidence about the effectiveness of testing, and reminders of how quick and easy it is to get a malaria test with the community case management initiative. Study findings also have implications for efforts to eliminate malaria across the Guiana Shield.

A qualitative study of community perspectives surrounding cleaning practices in the context of Zika prevention in El Salvador: implications for community-based Aedes aegypti control

Background

In El Salvador, Aedes aegypti mosquitoes transmitting Zika and other arboviruses use water storage containers as important oviposition sites. Promotion of water storage container cleaning is a key element of prevention programs. We explored community perceptions surrounding cleaning practices among pregnant women, male partners of pregnant women, and women likely to become pregnant.

Methods

Researchers conducted 11 focus groups and 12 in-depth interviews which included individual elicitations of Zika prevention measures practiced in the community. Focus group participants rated 18 images depicting Zika-related behaviors according to effectiveness and feasibility in the community context, discussed influencing determinants, voted on community intentions to perform prevention behaviors, and performed washbasin cleaning simulations. In-depth interviews with male partners of pregnant women used projective techniques with images to explore their perceptions on a subset of Zika prevention behaviors.

Results

General cleaning of the home, to ensure a healthy environment, was a strong community norm. In this context, participants gave water storage container cleaning a high rating, for both its effectiveness and feasibility. Participants were convinced that they cleaned their water storage containers effectively against Zika, but their actual skills were inadequate to destroy Aedes aegypti eggs. A further constraint was the schedule of water availability. Even during pregnancy, male partners rarely cleaned water storage containers because water became available in homes when they were at work. Furthermore, prevailing gender norms did not foster male participation in domestic cleaning activities. Despite these factors, many men were willing to provide substantial support with cleaning when their partners were pregnant, in order to protect their family.

Conclusions

Behavior change programs for the prevention of Zika and other arboviruses need to improve community members’ mosquito egg destruction skills rather than perpetuate the promotion of non-specific cleaning in and around the home as effective. Egg elimination must be clearly identified as the objective of water storage container maintenance and programs should highlight the effective techniques to achieve this goal. In addition, programs must build the skills of family members who support pregnant women to maintain the frequency of effective egg destruction in all water storage containers of the home.

Community Perspectives on Zika Virus Disease Prevention in Guatemala: A Qualitative Study

Zika virus, which is transmitted by Aedes aegypti mosquitoes and through sexual transmission, disproportionally affects the human fetus. Guatemala experienced a surge of Zika cases beginning in 2016. We conducted a qualitative study of community perceptions of the seriousness of Zika, as well as the effectiveness, feasibility, and collective efficacy of Zika prevention actions. Free listing elicited the preventive actions salient for 68 participants comprising pregnant women, men with a pregnant partner, and women likely to become pregnant; 12 focus group discussions in a highland and a lowland town explored other concepts through rank orderings of prevention practices depicted on cards. Participants' initial concern about Zika, based on recent experience with chikungunya and high media coverage, diminished because of its mild symptoms and reduced media coverage. Participants identified more than 32 salient preventive actions, many of which are considered effective by programs. Participants ranked water storage container cleaning and regular unspecified cleaning of the house and its surroundings as highly effective, feasible, and of high collective efficacy; however, the actions lacked the specificity needed to effectively destroy mosquito eggs. Community-level removal of tires and discarded containers had lower collective efficacy than household-level implementation because of the municipal and community cooperation needed. Condom use, although salient for Zika prevention, was hindered by gender roles. The findings indicate space for increasing self-efficacy for condom use among fathers-to-be, abandoning nonspecific terms such as "cleaning" and "standing water," increasing people's skills in using bleach as an ovicide, and promoting antenatal care and family planning counseling.

Barriers to dog rabies vaccination during an urban rabies outbreak: Qualitative findings from Arequipa, Peru

Background

Canine rabies was reintroduced to the city of Arequipa, Peru in March 2015. The Ministry of Health has conducted a series of mass dog vaccination campaigns to contain the outbreak, but canine rabies virus transmission continues in Arequipa’s complex urban environment, putting the city’s 1 million inhabitants at risk of infection. The proximate driver of canine rabies in Arequipa is low dog vaccination coverage. Our objectives were to qualitatively assess barriers to and facilitators of rabies vaccination during mass campaigns, and to explore strategies to increase participation in future efforts.

Methodology/Principal findings

We conducted 8 focus groups (FG) in urban and peri-urban communities of Mariano Melgar district; each FG included both sexes, and campaign participants and non-participants. All FG were transcribed and then coded independently by two coders. Results were summarized using the Social Ecological Model. At the individual level, participants described not knowing enough about rabies and vaccination campaigns, mistrusting the campaign, and being unable to handle their dogs, particularly in peri-urban vs. urban areas. At the interpersonal level, we detected some social pressure to vaccinate dogs, as well as some disparaging of those who invest time and money in pet dogs. At the organizational level, participants found the campaign information to be insufficient and ill-timed, and campaign locations and personnel inadequate. At the community level, the influence of landscape and topography on accessibility to vaccination points was reported differently between participants from the urban and peri-urban areas. Poor security and impermanent housing materials in the peri-urban areas also drives higher prevalence of guard dog ownership for home protection; these dogs usually roam freely on the streets and are more difficult to handle and bring to the vaccination points.

Conclusions

A well-designed communication campaign could improve knowledge about canine rabies. Timely messages on where and when vaccination is occurring could increase dog owners’ perception of their own ability to bring their dogs to the vaccination points and be part of the campaign. Small changes in the implementation of the campaign at the vaccination points could increase the public’s trust and motivation. Location of vaccination points should take into account landscape and community concerns.

Canine rabies was reintroduced in Arequipa, Peru in March 2015, a rare event in an area previously declared free of transmission. In Arequipa, annual mass dog vaccination is practiced as a preventive strategy, with additional campaigns being implemented since the recent detection of the virus. However, these additional efforts have not quelled the outbreak and low dog vaccination coverage is driving ongoing transmission. We conducted focus groups in urban and peri-urban areas of Arequipa to identify barriers to and facilitators of canine vaccination during mass campaigns. Based on our findings, communication campaigns should seek to increase knowledge about canine rabies and the vaccination campaign, and provide timely messages on where and when vaccination is occurring. Small changes at the campaign’s vaccination points could increase public’s trust. Finally, there are differences between urban and peri-urban areas, such as landscape and topography that affect participation in mass vaccination campaigns and that should be considered when selecting locations for vaccination points.

To spray or not to spray? Understanding participation in an indoor residual spray campaign in Arequipa, Peru

Current low participation rates in vector control programmes in Arequipa, Peru complicate the control of Chagas disease. Using focus groups (n = 17 participants) and semi-structured interviews (n = 71) conducted in March and May 2013, respectively, we examined barriers to and motivators of household participation in an indoor residual spray (IRS) campaign that had taken place one year prior in Arequipa. The most common reported barriers to participation were inconvenient spray times due to work obligations, not considering the campaign to be necessary, concerns about secondary health impacts (e.g. allergic reactions to insecticides), and difficulties preparing the home for spraying (e.g. moving heavy furniture). There was also a low perception of risk for contracting Chagas disease that might affect participation. The main motivator to participate was to ensure personal health and well-being. Future IRS campaigns should incorporate more flexible hours, including weekends; provide appropriate educational messages to counter concerns about secondary health effects; incorporate peer educators to increase perceived risk to Chagas in community; obtain support from community members and leaders to build community trust and support for the campaign; and assist individuals in preparing their homes. Enhancing community trust in both the need for the campaign and its operations is key.

"We are supposed to take care of it": a qualitative examination of care and repair behaviour of long-lasting, insecticide-treated nets in Nasarawa State, Nigeria

Background

The longevity of long-lasting insecticidal nets (LLIN) under field conditions has important implications for malaria vector control. The behaviour of bed net users, including net care and repair, may protect or damage bed nets and impact the physical integrity of nets. However, this behaviour, and the motivating and inhibiting factors, is not well understood.

Methods

Qualitative research methods were used to examine behaviour, attitudes and norms around damage, care and repair of LLINs. Eighteen in-depth interviews (IDI) and six focus group discussions (FGD) were conducted with LLIN users in two local government areas of Nasarawa State, Nigeria. A brief background questionnaire with the 73 participants prior to IDIs or FGDs collected additional data on demographics, net use, and care and repair behaviour.

Results

Respondents cited that the major causes of damage to bed nets are primarily children, followed by rodents, everyday handling that is not gentle, and characteristics of sleeping spaces. Caring for nets was perceived as both preventing damage by careful handling and keeping the net clean, which may lead to over-washing of LLINs. Repairing a damaged net was considered something that net users should do and the responsibility of adults in the household. Despite this, reported frequency of net repair was low (18%). Motivations for taking care of and repairing nets centred around caring for one’s family, avoiding mosquito bites, saving money, and maintaining the positive opinion of others by keeping a clean and intact net. Barriers to net care and repair related to time availability and low perceived value of bed nets or of one’s health.

Conclusion

This study provides novel and valuable insights on the perceptions and attitudes of LLIN users in Nasarawa, Nigeria on the durability of bed nets, how to care for and repair nets, and for what reasons. Communication around net care should stress proper daily storage of nets, regular net inspections, prompt repairs, and clarify misconceptions about proper washing frequency and technique. These messages should include compelling motivators, such as local social norms of household hygiene.

Provision of private, piped water and sewerage connections and directly observed handwashing of mothers in a peri-urban community of Lima, Peru

OBJECTIVES

To estimate the association between improved water and sanitation access and handwashing of mothers living in a peri-urban community of Lima, Peru.

METHODS

We observed 27 mothers directly, before and after installation of private, piped water and sewerage connections in the street just outside their housing plots, and measured changes in the proportion of faecal-hand contamination and hand-to-mouth transmission events with handwashing.

RESULTS

After provision of water and sewerage connections, mothers were approximately two times more likely to be observed washing their hands within a minute of defecation, compared with when they relied on shared, external water sources and non-piped excreta disposal (RR = 2.14, 95% CI = 0.99-4.62). With piped water and sewerage available at housing plots, handwashing with or without soap occurred within a minute after 48% (10/21) of defecation events and within 15 min prior to 8% (11/136) of handling food events.

CONCLUSIONS

Handwashing increased following installation of private, piped water and sewerage connections, but its practice remained infrequent, particularly before food-related events. Infrastructural interventions should be coupled with efforts to promote hygiene and ensure access to water and soap at multiple on-plot locations convenient to mothers.

A field trial of alternative targeted screening strategies for Chagas disease in Arequipa, Peru

BACKGROUND

Chagas disease is endemic in the rural areas of southern Peru and a growing urban problem in the regional capital of Arequipa, population ∼860,000. It is unclear how to implement cost-effective screening programs across a large urban and periurban environment.

METHODS

We compared four alternative screening strategies in 18 periurban communities, testing individuals in houses with 1) infected vectors; 2) high vector densities; 3) low vector densities; and 4) no vectors. Vector data were obtained from routine Ministry of Health insecticide application campaigns. We performed ring case detection (radius of 15 m) around seropositive individuals, and collected data on costs of implementation for each strategy.

RESULTS

Infection was detected in 21 of 923 (2.28%) participants. Cases had lived more time on average in rural places than non-cases (7.20 years versus 3.31 years, respectively). Significant risk factors on univariate logistic regression for infection were age (OR 1.02; p = 0.041), time lived in a rural location (OR 1.04; p = 0.022), and time lived in an infested area (OR 1.04; p = 0.008). No multivariate model with these variables fit the data better than a simple model including only the time lived in an area with triatomine bugs. There was no significant difference in prevalence across the screening strategies; however a self-assessment of disease risk may have biased participation, inflating prevalence among residents of houses where no infestation was detected. Testing houses with infected-vectors was least expensive. Ring case detection yielded four secondary cases in only one community, possibly due to vector-borne transmission in this community, apparently absent in the others.

CONCLUSIONS

Targeted screening for urban Chagas disease is promising in areas with ongoing vector-borne transmission; however, these pockets of epidemic transmission remain difficult to detect a priori. The flexibility to adapt to the epidemiology that emerges during screening is key to an efficient case detection intervention. In heterogeneous urban environments, self-assessments of risk and simple residence history questionnaires may be useful to identify those at highest risk for Chagas disease to guide diagnostic efforts.

Chagas disease, migration and community settlement patterns in Arequipa, Peru

BACKGROUND

Chagas disease is one of the most important neglected tropical diseases in the Americas. Vectorborne transmission of Chagas disease has been historically rare in urban settings. However, in marginal communities near the city of Arequipa, Peru, urban transmission cycles have become established. We examined the history of migration and settlement patterns in these communities, and their connections to Chagas disease transmission.

METHODOLOGY/PRINCIPAL FINDINGS

This was a qualitative study that employed focus group discussions and in-depth interviews. Five focus groups and 50 in-depth interviews were carried out with 94 community members from three shantytowns and two traditional towns near Arequipa, Peru. Focus groups utilized participatory methodologies to explore the community's mobility patterns and the historical and current presence of triatomine vectors. In-depth interviews based on event history calendars explored participants' migration patterns and experience with Chagas disease and vectors. Focus group data were analyzed using participatory analysis methodologies, and interview data were coded and analyzed using a grounded theory approach. Entomologic data were provided by an ongoing vector control campaign. We found that migrants to shantytowns in Arequipa were unlikely to have brought triatomines to the city upon arrival. Frequent seasonal moves, however, took shantytown residents to valleys surrounding Arequipa where vectors are prevalent. In addition, the pattern of settlement of shantytowns and the practice of raising domestic animals by residents creates a favorable environment for vector proliferation and dispersal. Finally, we uncovered a phenomenon of population loss and replacement by low-income migrants in one traditional town, which created the human settlement pattern of a new shantytown within this traditional community.

CONCLUSIONS/SIGNIFICANCE

The pattern of human migration is therefore an important underlying determinant of Chagas disease risk in and around Arequipa. Frequent seasonal migration by residents of peri-urban shantytowns provides a path of entry of vectors into these communities. Changing demographic dynamics of traditional towns are also leading to favorable conditions for Chagas disease transmission. Control programs must include surveillance for infestation in communities assumed to be free of vectors.

Direct observation of hygiene in a Peruvian shantytown: not enough handwashing and too little water

OBJECTIVE

To document frequency of hygiene practices of mothers and children in a shantytown in Lima, Peru.

METHODS

Continuous monitoring over three 12-h sessions in households without in-house water connections to measure: (i) water and soap use of 32 mothers; (ii) frequency of interrupting faecal-hand contamination by washing; and (iii) the time until faecal-hand contamination became a possible transmission event.

RESULTS

During 1008 h of observation, 55% (65/119) of mothers' and 69% (37/54) of children's faecal-hand contamination events were not followed within 15 min by handwashing or bathing. Nearly 40% (67/173) of faecal-hand contamination events became possible faecal-oral transmission events. There was no difference in the time-until-transmission between mothers and children (P = 0.43). Potential transmission of faecal material to food or mouth occurred in 64% of cases within 1 h of hand contamination. Mean water usage (6.5 l) was low compared to international disaster relief standards.

CONCLUSIONS

We observed low volumes of water usage, inadequate handwashing, and frequent opportunities for faecal contamination and possible transmission in this water-scarce community.

Predicting smoking stage of change among emergency department patients and visitors

OBJECTIVES

Little is known about whether emergency department (ED) patients or those who accompany them (visitors) are interested in smoking cessation. The authors hypothesized that several variables would be associated with stage of change, including nicotine dependence, self-efficacy, presence of a smoking-related illness, and anticipated cessation-related health improvement.

METHODS

For two 24-hour periods, consecutive patients and visitors aged 18 years and older presenting to four Boston EDs were interviewed. The authors assessed a range of smoking-related constructs. Exclusion criteria included severe illness, cognitive insufficiency, and acute distress.

RESULTS

One thousand ten subjects were screened (56% patients, 44% visitors). Two hundred thirty-seven (23%) subjects were current smokers, with 57% being in precontemplation, 31% in contemplation, and 12% in preparation stages. When ordinal regression was used, the variables most strongly associated with stage of change were as follows: self-efficacy (odds ratio [OR] = 5.1; p < 0.001), anticipated cessation-related health improvement (OR = 2.7; p = 0.02), and having a smoking-related health problem (OR = 1.9; p = 0.08).

CONCLUSIONS

Because many disenfranchised Americans use the ED as a regular source of health care, increased attention to smoking in the ED setting holds tremendous public health potential. This study's results reinforce the validity of the stage-of-change model within the ED setting. Developers of ED-initiated interventions will have to consider the heterogeneity in stage of change when designing their treatments.

T-lymphocyte Apoptosis Is Increased by Non-Interleukin-2-Dependent Induction in Human Mixed Lymphocyte Cultures

INTRODUCTION

Transplant tolerance is dependent on the apoptotic deletion of allospecific T lymphocytes following interleukin-2 (IL-2)-dependent T-lymphocyte activation. Current immunosuppressive strategies block IL-2 and may prevent T-cell activation. We examined apoptotic alterations in mixed lymphocyte culture (MLC), a model of allospecific lymphocyte activation, by polyclonal rabbit antithymocyte antibody thymoglobulin (rATG) and monoclonal anti-IL-2 receptor antibody basiliximab.

METHODS

Human lymphocytes were isolated using Ficoll-Paque gradient. Cesium-irradiated (2500 rad) stimulator cells (10(6) cells/mL) were cocultured with equal numbers of responder cells. Apoptosis was measured using annexin-V staining and propidium iodide exclusion using flow cytometry. Isolated protein was analyzed using Western blotting with densitometry.

RESULTS

Apoptosis increased at days 3 and 7 in rATG MLC compared with control and basiliximab MLC. Fas was up-regulated in rATG MLC in a dose-dependent manner, whereas basiliximab did not alter fas. FasL was increased initially and at late time points in rATG MLC.

CONCLUSIONS

Polyclonal rATG increased apoptosis and production of the proapoptotic proteins fas and fasL. In contrast, monoclonal basiliximab did not change lymphocyte apoptosis or apoptotic protein production. These results suggest that a specific IL-2 pathway blockade may prevent allospecific tolerance and that a non-IL-2 pathway blockade may encourage apoptosis of allospecifically activated T cells.

Effects of Rapamycin on the Arterial Inflammatory Response in Atherosclerotic Plaques in Apo-E Knockout Mice

Because of its antiproliferative properties and its known effects on plasma lipids, we evaluated the mechanisms underlying the effect of rapamycin (RPM) on endothelial nitric oxide synthase (eNOS) and matrix metalloproteinases in Apo-E knockout mice. Apo-E-/- mice fed a high-cholesterol diet were given RPM (3 mg/kg per day intraperitoneally) or no treatment for 10 weeks (n = 8 each). Blood was drawn for serum lipid analysis. Protein was extracted from the abdominal aortas for Western immunoblotting and zymography. Cellular localization was assessed by histology and immunohistochemistry. The data, expressed as mean +/- SEM, were compared by Student's t test or analysis of variance (ANOVA). Lipid levels at 10 weeks were similar in both groups except for higher triglyceride levels in RPM-treated animals. RPM-treated mice expressed greater amounts of eNOS and p-eNOS compared with controls (P < .05). Akt, p-Akt, Caveolin-1, and p-Caveolin-1 were not significantly affected by RPM treatment. RPM treatment was associated with increased activation of pro-MMP-9, a significant decrease in MMP-2 tissue levels, and corresponding increases in TIMP-2 and TIMP-3 expression. The increased expression and phosphorylation of eNOS with RPM appears to be regulated by mechanisms other than Akt or Caveolin-1. Alterations in eNOS expression, in addition to changes in MMP/TIMP ratios and MMP-2 and MMP-9 activation, may partially explain the changes observed in the aorta of treated Apo-E-/- mice induced by RPM.

Conversion From Cyclosporine to Tacrolimus Results in Improved Creatinine But Does Not Alter Lipid Profile

INTRODUCTION

While cyclosporine and tacrolimus use results in similar renal graft survival, the side effect profiles of the drugs are substantially different. We examined the electrolyte and lipid alterations that occurred in our patient population following conversion from cyclosporine to tacrolimus.

METHODS

Data for electrolytes, lipid profile, and immunosuppression were analyzed from 98 patients with kidney or kidney-pancreas transplants who were converted from cyclosporine to tacrolimus between October 1994 and June 2001. Results, expressed as mean +/- SEM, were compared to baseline values using the Wilcoxon signed-rank test (P < .05 considered significant).

RESULTS

Among these patients, there were 56 men, 42 women, 75 primary transplants, 15 repeat transplants, and 26 multiorgan transplants. The mean time to tacrolimus conversion was 769 +/- 122 days. Creatinine, BUN, and glucose improved after conversion to tacrolimus. Surprisingly, cholesterol, low-density lipoproteins, and high-density lipoproteins levels were not significantly altered, although triglyceride levels demonstrated a significant difference at 1 year.

CONCLUSION

Significant improvements in creatinine and BUN were observed following conversion from cyclosporine to tacrolimus. While hypomagnesemia was also seen, there was surprisingly little alteration in lipid profile.

Vein adaptation to arterialization in an experimental model

PURPOSE

The events preceding myointimal thickening in vein grafts after vascular reconstructions are not well characterized. Indeed, the injury response associated with vein graft arterialization may be different than that observed in the balloon angioplasty model. Therefore, we used a rat model to study the early cellular response after arterialization of vein grafts.

METHODS

Epigastric veins were placed as femoral artery interposition grafts in 37 male Lewis rats (weight range, 350-400 g). Vein grafts and contralateral epigastric veins were harvested at different time points (6 hours, 1 day, 2 days, 3 days, 7 days, 14 days, 21 days, 30 days, and 70 days). Tissue specimens were processed for histology and immunohistochemistry with antibodies for the proliferating cell nuclear antigen (PCNA) and for different cell types. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay was used as a means of determining the presence of apoptosis. Electron microscopy was used as means of assessing the integrity of the endothelial cell surface (SEM) and confirming the presence of apoptosis (TEM). Specimens were also snap frozen in liquid nitrogen for RNA isolation and molecular analysis.

RESULTS

At 1 day, endothelial denudation with platelet deposition on the surface was shown by means of SEM. Both apoptosis and necrosis of smooth muscle cells (SMCs) were present in the media, along with monocyte infiltration. Cellular proliferation and apoptosis were most intense within the first week of implantation. PCNA staining was first seen in the adventitial fibroblasts and microvessels, then in the medial SMCs at 3 days. With reverse transcriptase polymerase chain reaction, upregulation of vascular endothelial growth factor (VEGF) messenger RNA (mRNA) was noted at 1 day. Myointimal thickening progressively developed, with no apparent diminution of the luminal area as long as 70 days after implantation. By means of the analysis of the transforming growth factor beta1, mRNA showed expression during intimal thickening and accumulation of extracellular matrix. Reendothelialization was complete at 30 days.

CONCLUSIONS

These observations indicate that the cellular composition in our vein graft model is similar to human stenotic explants. Endothelial denudation is observed in rat vein grafts with complete regeneration by 30 days. VEGF mRNA is upregulated at 1 day, followed by proliferation of microvessel endothelial cells in the adventitia. Cellular proliferation and apoptosis are minimal after 21 days, with progressive intimal thickening likely to be the result of matrix accumulation.

Intimal growth and neovascularization in human stenotic vein grafts

BACKGROUND

Myointimal thickening and microvessel ingrowth are commonly observed in vein graft stenosis, which complicates a third of infrainguinal bypass procedures. But a direct correlation between these two features has not been established. Our purpose was to analyze the relationship between neovascularity and intimal thickness in human vein grafts.

STUDY DESIGN

Twenty-two explant stenotic vein grafts (STVG), 8 nonstenotic arterialized vein grafts (AVG), and 20 age-matched control greater saphenous veins (CGSV) were analyzed histologically and compared morphologically by light microscopy. Digitized computer image analysis was used to measure intimal thickness and quantitate microvessel ingrowth. Immunolocalization of endothelial cells around the lumen and in microvessels was determined using antibodies to factor VIII and to endothelial nitric oxide synthase (eNOS), respectively.

RESULTS

Focal areas of endothelial disruption and thrombus deposition were present in 23% (5 of 22) of stenotic vein grafts. The neointima of STVG grafts was two- and fourfold thicker than that of AVG and CGSV, respectively (p < 0.0001). Microvessels were most frequently observed in the adventitia and media of STVG and increased in number with increasing intimal thickness (p < 0.001 by ANOVA).

CONCLUSIONS

A fourfold increased neointimal thickness in critically stenotic vein grafts is associated with increased medial and adventitial neovascularization. Remodeling alone with doubling of the intimal thickness in nonstenotic arterialized vein grafts does not appear to be associated with enhancement of the graft microvasculature. More specific observations using an experimental model may allow us to further define the role of angiogenesis in vein graft stenosis and to determine the therapeutic implications of such observations.

The contribution of inducible nitric oxide and cytomegalovirus to the stability of complex carotid plaque

BACKGROUND

Although the association between inflammation and atherosclerosis is well established, the biologic events that trigger the local inflammatory response within plaque are not fully understood. Cytotoxic free radicals and infectious agents, both of which are associated with an inflammatory response, have previously been implicated in the initiation and progression of atherosclerosis. In this study, we analyzed carotid plaque for evidence of oxidative vascular injury by determining the presence and distribution of inducible nitric oxide synthase (iNOS) expression and nitrotyrosine formation and for evidence of infection with cytomegalovirus.

METHODS

Carotid plaque from 51 patients who underwent endarterectomy for either primary (n = 37) or recurrent (n = 14) stenosis were examined histologically (hematoxylin-eosin staining and Masson's trichrome staining) and with immunohistochemistry with specific antibodies to alpha-smooth muscle actin, macrophages (CD68), T-lymphocytes (CD3), and T-cell activation (human leukocyte antigen-DR). Twenty-eight specimens from patients with primary (n = 15) and recurrent (n = 13) stenosis were examined for the presence of iNOS and nitrotyrosine with immunohistochemistry and in situ hybridization (iNOS). Twenty-three additional specimens (22 primary, and 1 recurrent) were analyzed with antibodies to p53, cytomegalovirus, and the polymerase chain reaction (cytomegalovirus, n = 8).

RESULTS

Primary atherosclerotic lesions were either complex heterogenous cellular plaques (n = 29) or relatively acellular fibrous plaques (n = 8). Ten of 14 recurrent plaques were either complex or fibrous lesions, and the remaining four were typical of myointimal thickening. CD68-positive staining cells were detected in all specimens regardless of their structural morphology. CD3-positive cells were interspersed between macrophages in all heterogeneous cellular plaques and only infrequently noted in fibrous plaques. iNOS and nitrotyrosine immunoreactivity were detected in macrophages and smooth muscle cells in all complex and fibrous plaques and in two of four myointimal plaques. The presence of iNOS and nitrotyrosine in plaque correlated with the existence of symptoms in 80% of primary and 62% of recurrent lesions. Cytomegalovirus was detected in only two of 23 carotid specimens (9%).

CONCLUSION

The association between ischemic cerebrovascular symptoms and iNOS and nitrotyrosine immunoreactivity in complex primary and recurrent carotid plaque and the infrequent occurrence of cytomegalovirus in primary carotid lesions suggests that ongoing free radical oxidative damage rather than viral infection may contribute to plaque instability in patients with complex and fibrous carotid plaques.

Antioxidant enzyme activity in human abdominal aortic aneurysmal and occlusive disease

The present study further investigates evidence for lipid peroxidation in atherosclerotic aortic tissue by determining the activity of antioxidant enzymes and concentrations of lipid peroxide fluorochromes in abdominal aortas from 15 patients with abdominal aortic aneurysms (AAA), an additional 7 patients with ruptured abdominal aneurysms, and 12 patients with atherosclerotic occlusive disease (AOD). Aortas from nonatherosclerotic organ donors served as nondiseased controls. Cu, Zn-superoxide dismutase (Cu,Zn-SOD) activities in AAA and AOD tissues were 16% and 25% of control activity, respectively. Mn-SOD activity in diseased aortae were about 65% of controls. CuZn-SOD protein in AAA and AOD was 56% and 100% of controls, respectively, resulting in significantly lower CuZn-SOD specific activity in these tissues. Ruptured AAA tissue also had low SOD activity and protein. Glutathione peroxidase (GPx) activity in AAA and AOD aortas was 70% and 65% of controls, respectively, and glutathione reductase (GR) activity in AAA and AOD aortas was 80% and 65% of control activities, respectively. These results were associated with significantly higher lipid peroxide fluorochromes, expressed as U/g aorta, in both groups of atherosclerotic aortas than in controls. AOD aortas had 33% higher fluorescence than AAA aortas, but the highest levels were seen in ruptured AAA. These data further support the involvement of free radicals and lipid peroxidation in atherosclerotic aortic disease, but do not indicate that these mechanisms are specifically involved in aneurysm formation versus development of occlusive disease.

Topography of cell replication in human vein graft stenoses

BACKGROUND

Analysis of the cellular composition of human autogenous vein graft lesions at the time of revision provides an opportunity to identify the cellular processes leading to the development of stenosis in humans after vascular reconstruction.

METHODS AND RESULTS

Human vein graft-threatening stenotic lesions were identified by duplex scanning within 3 to 18 months after infrainguinal bypass and surgically removed. They were serially studied by immunocytochemistry for expression of the proliferating cell nuclear antigen (PCNA) in different cell types: alpha-actin-positive smooth muscle cells (SMCs), endothelial cells (ECs), monocytes, and macrophages. Proliferation indexes were separately obtained for each layer of the vessel wall by determining the mean percentage of PCNA-positive nuclei among the total number of nuclei present within the intima, the media, and the adventitia, respectively. The percentage distribution of the replicating cell types was also determined. We report that in autogenous vein graft (n = 14) the intima of the lesion displayed fewer PCNA + nuclei (1.03 +/- 0.88) than the underlying media (3.14 +/- 0.74) or the adventitia (3.01 +/- 0.74). Replicating SMCs were predominantly in the medial layer (68% of PCNA + cells) of stenotic vein grafts. In the adventitia, the proliferation was most intense in the endothelium of microvessels (65% of PCNA + nuclei).

CONCLUSIONS

Our findings reveal a 3-fold greater proliferative activity in the media and the adventitia as compared with the intima of autogenous vein graft lesions, in contrast to cellular proliferation identified in recurrent coronary stenotic plaques. Moreover, there are distinctive patterns of distribution of the different cell populations among the 3 layers. The results indicate a proliferative response of the media and the adventitia of autogenous vein grafts transplanted into the arterial circulation, in addition to the cellular proliferation observed in the intima of the lesion.

Current trends in the detection and management of carotid body tumors

PURPOSE

Because the natural history of carotid body tumors is believed to be unpredictable, immediate surgical removal has been recommended. The present study reviews our experience in the diagnosis and treatment of these uncommon lesions.

METHODS

The medical records of patients who appeared for treatment with carotid body tumors between 1981 and 1997 were reviewed. Patients demographics, mode of presentation, imaging and treatment modalities, Shamblin classification, and neurologic complications (stroke, cranial nerve injuries) were analyzed.

RESULTS

Over the past 16 years, 31 patients with 32 carotid body tumors have been evaluated, with an average follow-up of 3.2 years. The patients were arbitrarily classified into two groups on the basis of the mode of detection. Seventy percent (23 of 32) of the tumors discovered on clinical or self-examination were classified as Group 1; 28% (9 of 32) of the tumors detected during duplex scanning for carotid artery disease (8) or MRI (1) were classified as Group 2. The mean size of chemodectomas found on palpation (4.3 +/- 1.7 cm) was larger than that of those detected by duplex ultrasound (2.7 +/- 1.0 cm; p < 0.05, by paired t test). Preoperative embolization was successfully performed in 5 of 6 instances of large tumors; the remaining patient suffered a procedure-related stroke. Thirty-one carotid body tumors were resected. In one case, the tumor was felt by the primary surgeon to be too small (0.9 x 0.7 cm on duplex scan) to warrant immediate excision; this patient is being followed by periodic duplex scanning. Five neurologic complications were noted in Group 1, one after preoperative embolization and four after surgery. One cranial nerve injury occurred in Group 2. One patient had a large recurrent chemodectoma with clinical evidence of metastatic disease.

CONCLUSION

The increasing use of sophisticated imaging modalities may allow earlier discovery of carotid body tumors before they can be clinically detected. Resection of carotid body tumors of all sizes in appropriate surgical candidates remains the standard of care. Unfortunately, resection of even small tumors is associated with a low but constant incidence of neurologic complications.

The histologic characteristics of primary and restenotic carotid plaque

BACKGROUND

Although smooth muscle cell proliferation is a prominent feature of restenosis in experimental models, the role of cellular proliferation in the initiation and progression of carotid restenosis is not well documented.

METHODS

Between 1985 and 1995, 35 carotid endarterectomies (CEA) in 34 patients were performed for restenosis. Patient risk factors, cerebrovascular symptoms, and operative findings were recorded. Tissue specimens from 29 of these cases and 14 original specimens from the same patient were examined by light microscopy (H&E, trichrome, elastochrome, and Alcian blue) and immunohistochemistry (alpha actin, CD 68, vWF, and proliferating nuclear cell antigen (PCNA)) in order to determine the morphologic characteristics and cellular proliferative activity of the plaque.

RESULTS

Hemodynamically significant recurrent stenosis occurred in the 29 patients (69% symptomatic) between 2 months and 30 years after their initial CEAs. Eleven of 29 (38%) lesions were removed early (< 3 years). Recurrent lesions were characterized based on their components as neointimal thickening, 24% (7/29), neointimal thickening and atherosclerosis, 55% (16/29), or atherosclerotic, 21% (6/29). Nineteen of 29 (66%) plaques were complicated by mural thrombus or intraplaque hemorrhage. An inflammatory cell infiltrate consisting of macrophages and T lymphocytes was observed adjacent to areas of recurrent atherosclerosis and macrophages in regions of intimal thickening. Although infrequently present (generally 1-3% of cells) PCNA-positive cells were detected in 41% (12 of 29) of recurrent and 14% (2 of 14) of primary plaques. No PCNA-positive cells were detected in the remaining 67% (29 of 43) of specimens. There was no statistical difference in the number of PCNA-positive cells in early recurrent lesions compared to those recurring after 3 years (36% vs 44%). PCNA immunoreactivity when present was most commonly noted in macrophages associated with thrombus or atheroma rather than smooth muscle cells.

CONCLUSIONS

Although evidence of cellular proliferation was observed in 40% of recurrent carotid endarterectomy lesions, the proliferation rate was low (1-3%) and unrelated to the time interval of recurrence. Proliferative activity was most pronounced in macrophages associated with intraplaque hemorrhage or atheroma. The contribution of inflammatory cells to the biologic behavior of restenotic lesions requires further investigation.

Free tissue transfer to extend the limits of limb salvage for lower extremity tissue loss

BACKGROUND

The extent of tissue loss amenable to primary healing after revascularization is unknown. Salvage of limbs with large soft-tissue defects with exposed tendon, joint, or bone lies beyond the limits of conventional techniques. We report our results using free tissue transfer as an adjunct to lower extremity vascular reconstruction in patients with complex ischemic or infected wounds.

METHODS

Retrospective chart review of patient and wound characteristics.

RESULTS

From January 1992 to June 1996, 585 procedures were performed in 544 patients, including 27 free flaps in 26 patients: 17 free flaps combined with distal bypass (7 staged, 10 simultaneous) and 10 isolated free flaps. Flap donor sites included radial forearm (8), latissimus dorsi (7), rectus abdominus (9), and scapula (3). Surgical indications included extensive ischemic/neurotrophic ulcers, and nonhealing vein graft harvest incision or transmetatarsal amputation site. Mean area of tissue loss was 70 cm2, mean ulcer duration was 5 months, and 92% of patients had exposed tendon, joint, or bone. During a mean follow-up of 14 months, 2 patients died of cardiopulmonary disease and 3 flaps failed, resulting in below-knee amputation. Six flaps were revised for graft stenosis (1), venous thrombosis (1), or flap edge necrosis (4). Limb salvage rate was 70% at 24 months by life-table analysis. Functional ambulation was achieved in 21 of 24 (88%) patients, including 7 of 8 with diabetes, end-stage renal disease, and heel ulcers.

CONCLUSION

In select ambulatory patients with large soft-tissue defects and exposed deep structures, functional limb salvage is obtainable in more than 80% of patients. For lesions not amenable to vascular reconstruction with conventional methods of wound coverage, free tissue transfer extends the limits of limb salvage and is a viable alternative to amputation.

Edgar J. Poth Memorial/W.L. Gore and Associates, Inc. Lectureship. The clinical and pathological spectrum of recurrent carotid stenosis

BACKGROUND

Hemodynamically significant (> or =50%) carotid restenosis occurs in approximately 10% to 12% of individuals undergoing carotid endarterectomy. The underlying pathology is usually neointimal thickening within 3 years and recurrent atherosclerosis thereafter. Although a number of etiologic factors have been implicated in the development of restenosis, the etiology remains unclear and preventative measures relatively ineffective.

METHODS

A review of the English literature was undertaken to determine the incidence, clinical presentation, and pathologic features of carotid restenosis.

CONCLUSIONS

Carotid restenosis is the major factor limiting long-term patency after carotid endarterectomy. Although drug therapy has been shown to be effective in preventing restenosis in animal models, the results of clinical human trials have been disappointing. Delineation of the biochemical and molecular mechanisms contributing to the development of restenosis is essential if effective therapeutic interventions are to be developed.

Distal revascularization-interval ligation for limb salvage and maintenance of dialysis access in ischemic steal syndrome

PURPOSE

Traditional options for treating ischemic steal syndrome related to a functioning dialysis access graft or fistula include banding or ligation. Unfortunately, these techniques usually result in inconsistent limb salvage, loss of a functional access, or both. We report our experience with an alternative method of limb revascularization that eliminates steal while maintaining continuous dialysis access.

METHODS

Patients who had critical limb ischemia and functioning arteriovenous fistulae (AVF) underwent color-flow duplex scanning, digital photoplethysmography, and arteriography. Arterial ligation distal to the AVF origin eliminated the steal physiologic mechanism while arterial bypass grafting from above to below the AVF revascularized the extremity (distal revascularization-interval ligation [DRIL] procedure).

RESULTS

From March 1994 through December 1996, 21 patients with functioning extremity AVFs presented with critical ischemia and steal syndrome. Eleven patients had chronic ischemia with rest pain, paresthesias, or ulcerations related to nine native fistulae (six brachiocephalic, two basilic vein transpositions, one radiocephalic) and two prosthetic bridge grafts (one upper arm, one lower extremity). Acute ischemia developed in 10 patients related to three native fistulae (two brachiocephalic, one radiocephalic) and seven prosthetic bridge grafts (three forearm, three lower extremity, one upper arm). All 21 patients were treated with the DRIL technique. Three of these patients required treatment for ischemia at the time of AVF construction. Nineteen of 21 bypass procedures were performed with autogenous vein, including nine brachial-brachial, three brachial-radial, two radial-radial, two brachial-ulnar, one popliteal-popliteal, one femoral-popliteal, and one femoral-peroneal. Polytetrafluoroethylene grafts were used for one external iliac-popliteal bypass graft and one axillary-brachial bypass graft. Limb salvage and maintenance of a functional fistula were achieved in 100% and 94%, respectively, at 18 months by life-table analysis.

CONCLUSION

The DRIL technique reliably restores antegrade flow to the ischemic limb, eliminates the potential pathway for the steal physiologic mechanism, and maintains continuous dialysis access in these difficult patients.

Identification of predictors for lower extremity vein graft stenosis

BACKGROUND

The cause of intrinsic vein graft stenosis, which develops in at least 20% of infrainguinal autogenous bypass grafts during the intermediate follow-up interval, is unknown. We performed standard duplex surveillance of all lower extremity bypass grafts and evaluated the potential of comorbid patient risk factors that might predict development of vein graft flow disturbance or high-grade graft stenosis.

METHODS

Patients with at least 6 months of postoperative duplex surveillance were identified through our vascular registry. The association of clinical and hemodynamic profiles of graft performance were compared with specific patient risk factors, including demographics, cigarette smoking, antihypertensive medical therapy, type and quality of conduit, degree of ischemia, bypass run-off, and presence of infection, using stepwise logistic regression analysis.

RESULTS

Ninety-three patients (55 male, 38 female; mean age 69) underwent 100 infrainguinal bypasses. Twenty-six high-grade graft stenoses (>70%) were identified in 26 patients during follow-up (mean 21 months) by graft-flow peak systolic velocity (PSV) >300 cm/sec on more than one duplex examination, and were electively revised. Graft flow disturbances (180 cm/sec >PSV <300 cm/sec) were identified in an additional 13 grafts (6 regressed, 7 observed). The need for graft revision was associated with an early graft flow disturbance (P = 0.02), or drop in ankle-brachial index >0.15 (P = 0.03), and the use of an alternative conduit in 13 of 100 grafts (P = 0.04). Only smoking was associated with the development of a duplex detected graft flow disturbance during follow up (P = 0.03).

CONCLUSION

Grafts with early flow disturbances warrant close duplex surveillance to identify graft-threatening stenosis. Risk factors that may predict future lower extremity bypass graft stenosis are smoking and the use of alternative bypass conduits.

MRI and NMR spectroscopy of the lipids of atherosclerotic plaque in rabbits and humans

The early stages of atherosclerosis are characterized by the deposition of cholesteryl esters and triglycerides into the arterial wall. In the excised human atherosclerotic plaque these lipids are in a liquid-like state at body temperature and observable via MRI and NMR spectroscopy. To assess the ability of MRI to quantitatively image the lipids of atherosclerotic plaque in vivo, we have investigated eight New Zealand White rabbits fed atherogenic diets (2 weight (wt)% cholesterol, 1 wt% cholesterol + 6 wt% peanut oil, and 1 wt% cholesterol + 6 wt% com oil). Postmortem examination indicated that all rabbits developed atherosclerosis in the aorta. Except for one animal, magnetic resonance angiography showed no noticeable obstruction in the aorta. MRI was carried out in an attempt to image atherosclerotic plaque lipids directly, but no signal was detected in vivo. However, a plaque lipid signal was observed from excised tissue using a small diameter RF coil. 1H NMR spectroscopy of the atherosclerotic plaque from excised aortas indicated that the major fraction of plaque lipids in rabbits is not in a liquid state at physiological temperature and are only marginally MRI-visible compared to human plaque lipid. The differences in the MRI characteristics of rabbit and human plaque are due to differences in the fatty acid profile of the cholesteryl esters, chiefly a decrease of linoleic acid in rabbit lesions.

Lower extremity iatrogenic nerve injury due to compression during intraabdominal surgery

BACKGROUND

latrogenic nerve injury due to poor positioning and external compression is a common surgical complication. However, sciatic neuropathy from external compression and femoral nerve injury after self-retaining retraction are less-published complications.

METHODS

Surgical Morbidity and Mortality Reports from 1986 through 1995 were reviewed to identify femoral and sciatic neuropathies following intraabdominal vascular and general surgeries.

RESULTS

Two sciatic and 5 femoral neuropathies were reported, an incidence of approximately 0.17% of abdominal cases. Sciatic injuries were attributed to external compression, whereas femoral neuropathies were due to compression by self-retaining retraction. The 3 female and 4 male patients had a mean age of 53.4 years, and no patient had a prior history of peripheral neuropathy. Mean operating time for sciatic injuries was 8.2 hours, versus 4.3 hours for femoral neuropathies. Both patients with sciatic neuropathy had complete resolution of symptoms, compared with 1 femoral neuropathy patient. Two femoral neuropathies were permanent, 1 had partial resolution and 1 had improvement at 4 months but was lost to follow-up.

CONCLUSIONS

Sciatic and femoral compression neuropathies are rare but serious complications of abdominal surgery. When retracting in the deep pelvis, consideration should be given to using small, well-padded retractor blades and repositioning these regularly. Prevention of sciatic nerve compression requires careful padding of the table surface, especially for longer cases.

Endothelium on the flow surface of human aortic Dacron vascular grafts

PURPOSE

We have previously observed endothelium on two human vascular prostheses explanted under optimal conditions for flow surface preservation. In this study we sought to further verify the hypothesis that endothelialization can occur on clinical grafts and that it can be detected in specimens that have been promptly removed and properly preserved in a timely manner.

METHODS

We studied 29 aortic grafts. Of these, 11 Dacron bypass grafts were in a condition suitable for analysis with light microscopy and immunocytochemistry staining, and scanning and transmission electron microscopy.

RESULTS

Three grafts had endothelium beyond the pannus, identified by factor VIII/ vWF, Ulex europaeus agglutinin, and collagen IV positivity. Specimen A, a knitted 6-year implant, was preserved by embalming 3 hours after the patient's death and had a firmly attached outer capsule with fibroblasts, collagen, giant cells, and microvessels in the interstices. Specimen B, a woven 18-year implant, was retrieved at reoperation and immediately fixed in 10% formalin; it had no outer capsule and no tissue ingrowth. Specimen C, a woven 7-year implant, was removed and fixed 5 hours after the patient's death; it had a firmly attached outer capsule but no tissue ingrowth beyond the outer portion of the wall.

CONCLUSIONS

The rapidity with which the specimens were fixed probably enabled identification of endothelium. These findings suggest that endothelialization of synthetic arterial grafts may occur more frequently in human beings than previously recognized.

Immunocytochemical determination of cell type and proliferation rate in human vein graft stenoses

PURPOSE

Vascular reconstructions are prone to fail as a result of the development of stenotic lesions, which have historically been attributed to myointimal hyperplasia. In animal models, these lesions are associated with marked proliferative smooth muscle cell (SMC) response to vascular injury. However, recent studies using sensitive immunocytochemical techniques in human lesions have generally failed to detect significant cellular proliferation. To clarify the role of cellular proliferation in humans, we characterized the cellular composition and proliferative index of 14 early infrainguinal vein graft stenoses.

METHODS

All infrainguinal vein grafts at our institution are prospectively enrolled in a duplex surveillance protocol, the details of which have been previously reported. Among 98 grafts placed within the last year, 11 patients were identified with 14 progressive, focal, high-grade lesions that met previously established threshold criteria for prophylactic revision to prevent graft thrombosis. Lesions were first detected from 1 week to 7 months after surgery and were removed and replaced with segmental interposition grafts (1.5 to 10 months). Freshly excised lesions were placed in Methyl Carnoy's fixative, paraffin embedded, and serially sectioned. The cellular composition of each lesion was determined with cell-specific immunochemical reagents: alpha SMC actin, von Willebrand factor (endothelial cell), CD 68 (macrophage), and CD 45RB (monocyte). Actively proliferating cells were identified using antibody to proliferating cell nuclear antigen (PCNA). The identity of PCNA-positive cells was determined by double-label immunocytochemical staining, and the proliferative index (PCNA-positive cells/total cells x 100) was calculated by computer-assisted counts of representative gridded cross-sections of each lesion.

RESULTS

All excised lesions demonstrated marked thickening with severe luminal encroachment and were highly cellular, with a predominance of alpha SMC actin+. Endothelial cells on the blood flow surface were present to a variable degree, and seven lesions exhibited striking numbers of macrophages and monocytes. The latter cell types were most abundant near microvessels in the deep neointima and adventitia. Active cellular proliferation was identified primarily in SMCs, with a mean PCNA index of 1.34%. However, significant PCNA reactivity was not limited to SMCs, but was also identified in macrophages and monocytes, particularly in lesions greater than 3 months old.

CONCLUSIONS

Previous immunocytochemical studies of human coronary restenosis atherectomy specimens have generally detected low rates of cellular proliferation (0.5%), but these lesions may not truly represent myointimal hyperplasia, rather a mixture of atherosclerosis, thrombosis, and "restenosis." In contrast, the present study of early human vein graft lesions detected by duplex surveillance indicates that significant cellular proliferation occurs, although rates are lower than those obtained in animals such as the rat carotid injury model. In addition, although SMCs are the predominant proliferating cell type in human vein grafts, our identification of proliferating monocytes and macrophages raises the question of the contribution of an inflammatory component to the development of human lesions. The present study represents the first report of PCNA determination in a series of human infrainguinal vein grafting procedures.

The influence of routine completion arteriography on outcome following carotid endarterectomy

The necessity for routine completion arteriography (RCA) following carotid endarterectomy (CEA) is controversial, with the reported yield of clinically significant findings varying from 3% to 16%. In order to determine the utility of RCA, we reviewed completion studies in 154 consecutive CEAs, defined the frequency and characteristics of arteriographic defects, and correlated RCA defects with early outcome (internal carotid artery [ICA] occlusion, stroke) and late restenosis. All intraoperative RCAs were reviewed by two blinded observers and categorized into three subsets: Group A (n = 69) normal; Group B (n = 29), abnormal, severe defects; Group C (n = 56), abnormal, mild-moderate defect. RCA detected 32 defects in Group B: 10 internal carotid (ICA), seven endpoint flaps, two kinks, one dissection; 16 external carotid (ECA), 10 severe endpoint defects and six total occlusion; six common carotid (CCA), five irregular proximal shelfs, one web. Thirty of 32 defects were successfully repaired as confirmed by normal repeat RCA studies; one ECA defect was not repaired and the ICA dissection was irreparable. In Group C, 67 mild-moderate defects were identified, but not corrected. These included < 30% stenosis in the ICA (12), ECA (18), CCA (24), and vein patch corrugation or irregularity (13). For the entire series the postoperative ICA occlusion rate was 2% (3/154), stroke rate 2.6% (4/154), and a subsequent > 50% restenosis rate of 7% (11/154). The yield from routine carotid completion arteriograms was significant, with 19% of studies identifying a severe defect that required repair. Although the difference in stroke rates and restenosis between the different groups did not reach statistical significance, patients with normal intraoperative arteriograms initially or after correction of a significant RCA defect had no early carotid occlusion (p = 0.05, Fisher's exact test) compared to patients with residual RCA defects. All early carotid occlusions occurred in patients with unrepaired defects. We conclude that RCA is an important method of quality control after CEA and exerts a subtle, but real, reduction in postoperative complications.

Prospective validation of threshold criteria for intervention in infrainguinal vein grafts undergoing duplex surveillance

Although color flow duplex surveillance (CFDS) of infrainguinal vein grafts has gained wide acceptance, definitive criteria mandating graft revision remain to be established. We prospectively evaluated 101 infrainguinal vein grafts undergoing CFDS in order to validate threshold duplex criteria for intervention which were derived from our previous experience and that reported by others. Complete CFDS of the bypass conduit and adjacent inflow and outflow arteries and Doppler-derived ankle brachial indices (ABI) were obtained every 3 months x 4 and every 6 months thereafter. The following threshold criteria mandating further evaluation and intervention to prevent graft occlusion were applied: high-velocity criteria (HVC) defined as peak systolic velocity (PSV) > 300 cm/sec and velocity ratio (Vr) > 3.5; low-velocity criteria (LVC) defined as PSV < 45 cm/sec; an ABI decrease > 0.15. Fifty-one grafts had normal serial CFDS and ABI; none subsequently occluded or required revision. Stenosis was detected by CFDS in 43 grafts (PSV > 180 cm/sec, Vr > 1.5). Within this subgroup, 54% of grafts subsequently required revision (20/43) or occluded (3/43). All grafts in this subgroup with stenoses progressed to PSV > 300 or Vr > 3.5 prior to revision or occlusion. Ten lesions (23%) regressed spontaneously without intervention (mean PSV 252 cm/sec, mean Vr 3.2); 10 lesions (23%) are stable, non-progressive, and remain under surveillance. Two grafts were abnormal by LVC; one was successfully revised, the other occluded prior to intervention. Five grafts had normal CFDS and ABI decrease > 0.15. Four were revised (three inflow lesions, one outflow lesion) and one occluded (missed lesion by CFDS). Only five graft occlusions occurred in the entire series: three grafts met HVC and occluded prior to intervention; one developed an ABI drop of 0.4 due to graft stenosis missed by CFDS and uncovered following thrombolysis, and the other graft met LVC and occluded prior to intervention. Infrainguinal vein grafts with normal serial CFDS and ABI are at minimal risk of spontaneous graft occlusion. When CFDS is abnormal (PSV > 180 cm/sec, Vr > 1.5), over 50% of grafts will ultimately require revision or progress to occlusion. Grafts with such lesions can be safely monitored by CFDS until progression to lesions meeting HVC occurs with minimal risk of graft occlusion. A decrease in ABI > 0.15 with normal CFDS mandates arteriography to identify inflow and outflow lesions or a missed graft stenosis. The present study prospectively validates threshold intervention criteria for graft lesions meeting HVC (PSV > 300 cm/sec, Vr > 3.5), LVC (PSV < 45 cm/sec throughout graft) or an ABI decrease > 0.15.

Clinical presentation and management of iatrogenic colon perforations

BACKGROUND

Because iatrogenic colonic perforation is uncommon, surgical management of this complication has been based on the civilian trauma experience. In this study, we determine the incidence, clinical presentation, and management of colonic perforations resulting from colonoscopy or barium enema.

PATIENTS AND METHODS

The medical records of all patients with colorectal perforations due to barium enema or colonoscopy seen over a 5-year period were reviewed.

RESULTS

Twenty-one patients, 12 males and 9 females aged 66 +/- 16 years, undergoing evaluation for polyps and bleeding (11), diverticulosis (4), diarrhea (2), or miscellaneous indications (4) sustained colonic perforation from colonoscopy (18; 0.20%) or barium enema (3; 0.10%). Abdominal pain, 66% (13), and fever, 24% (5), were the most frequent symptoms encountered and extraluminal air, 67% (14), the most common radiologic finding. The site of perforation was the rectosigmoid in 62% (13) of patients. Eighteen patients underwent surgery; 11 within 24 hours (group I) and 7 patients within 6.0 +/- 4 days (group II). Fifty percent (9 of 18) had primary repair or resection with anastomosis without mortality. Of the 6 patients initially treated nonoperatively, 3 subsequently underwent surgery. Both deaths, one in group I and one in group II, occurred in patients who had colonic diversion for perforation following colonoscopy.

CONCLUSION

We conclude that in the absence of significant contamination either primary repair or resection and anastomosis can be performed with acceptable morbidity for iatrogenic perforations of the colon.

Vitamin E levels in human atherosclerotic plaque: the influence of risk factors

Recent studies suggest that vitamin E may be an important preventative factor in the development and progression of atherosclerosis. In order to more clearly define the role of vitamin E in atherosclerosis, we measured vitamin E, conjugated diens, and lipid flurochromes, as well as cholesterol, triglycerides and phospholipid in arterial and venous tissue of 83 patients. Serum cholesterol and triglyceride levels were significantly higher (P < 0.05) in patients with aortic occlusive (AIOD) and aneurysmal (AAA) disease than in control organ donors (OD). Tissue cholesterol concentrations were significantly elevated in AAA tissue when compared to OD and tissue from patients with peripheral occlusive disease (POD). Tissue from patients with AIOD contained greater concentrations of phospholipid (PL) than were measured in patients with POD and in OD. Vitamin E concentrations were highest in POD tissue and approximately 3.0, 2.0, and 1.6 fold greater than OD, AIOD and AAA tissue respectively. Diene conjugates and lipid flurochromes, measures of early and intermediate products of lipid peroxidation, were markedly elevated in all diseased arterial tissue compared to controls. There were no significant differences in tissue or serum lipid levels between saphenous vein (SVBG) and diseased vein grafts (DVG). However, conjugated diene concentrations were elevated in DVG compared to SVBG. Vitamin E levels were significantly elevated in diseased arterial and venous tissue (AIOD, AAA, POD, DVG) removed from patients with diabetes (P = 0.013) and hypertension (P = 0.049) compared to those without these risk factors. Diabetes was the only risk factor associated with significantly increased (P = 0.005) levels of vitamin E when only data from atherosclerotic arterial tissue (AAA, POD, AIOD) were analyzed. These preliminary data provide additional evidence of altered vitamin E metabolism and free radical processes in the tissues of patients with various manifestations of atherosclerosis.

Incidence and histologic characteristics of blebs in patients with abdominal aortic aneurysms

PURPOSE

Aortic blebs-focal outpouchings within aortic aneurysms-may contribute to their eventual rupture. In this study we determine the incidence of aortic blebs and describe their microscopic features.

METHODS

Computed tomographic scans of the abdominal aorta were obtained in 188 patients with aortic diameters measuring > or = 3 cm and were independently evaluated by a radiologist. The number and location of blebs were recorded, and each was measured with calipers. Sixteen blebs, with an adjacent uninvolved aneurysmal segment of aorta, and tissue from two patients with ruptured aneurysms were examined by light microscopy and immunohistochemical analysis. Specimens from six blebs and five aneurysms were examined for alpha 1 (I) procollagen messenger RNA by in situ hybridization.

RESULTS

Twenty blebs, ranging in size from 5 to 30 mm (mean, 12 +/- 7 mm), were detected in 11% (20 of 188) of computed tomographic scans. Blebs were observed in 10% (11 of 111) of patients with aortic diameters between 3.0 and 4.9 cm, 10% (6 of 61) of patients with aneurysms between 5.0 and 6.9 cm, and 19% (3 of 16) of patients with aortic diameters > or = 7 cm. Histologically, the major difference between the aneurysmal aortic wall and blebs was found in the media. In aneurysmal aortas, the media consisted of multiple layers of fragmented elastic lamellae, whereas the number of elastic tissue elements along the circumference of the blebs progressively decreased; only a few isolated fragments of elastic tissue were present at the apices. Histologic evidence of rupture was evident in two specimens. A chronic inflammatory cell infiltrate composed of T and B lymphocytes, plasma cells, and macrophages, common to both the aneurysmal and the blebs, was most prominent in the adventitia of aneurysmal tissue, but involved both the media and adventitia of the blebs. In situ hybridization demonstrated the presence of alpha 1 (I) procollagen messenger RNA in four of the five aneurysm segments that were evaluated, compared with only one of six blebs.

CONCLUSIONS

Blebs were discovered in aneurysms of all sizes; their frequency appeared to be unrelated to aneurysm size. The presence of inflammatory cell infiltrates and absence of alpha 1 (I) procollagen messenger RNA in five of six blebs suggest that a local imbalance of matrix degradation and repair plays a role in the cause of these lesions. Attenuation of the aortic wall accompanying the formation of blebs may predispose these sites to rupture.

The relative contributions of carotid duplex scanning, magnetic resonance angiography, and cerebral arteriography to clinical decisionmaking: a prospective study in patients with carotid occlusive disease

PURPOSE

Recent reports suggest that 80% to 90% of patients can safely undergo carotid endarterectomy on the basis of duplex scanning alone without cerebral angiography. Other investigators have recommended that a complementary imaging study such as magnetic resonance angiography (MRA) also be obtained.

METHODS

We prospectively evaluated 103 consecutive patients with carotid occlusive disease. Eighty percent of patients were symptomatic. All 103 patients underwent duplex scanning and arteriography. Additional noninvasive tests included computed tomography, magnetic resonance imaging, and MRA in 50%, 56%, and 48% of patients, respectively. At a multispecialty conference all studies except angiograms were reviewed, and a treatment decision was made by a panel of attending vascular surgeons, neurosurgeons, and neurologists. The cerebral angiograms then were reviewed and changes made to final treatment plans were noted.

RESULTS

After review of noninvasive studies, 30 of 103 of patients (29%) were believed to require arteriography because of diagnostic uncertainty of carotid occlusion in three patients, suggestion of nonatherosclerotic disease in four, suggestion of proximal disease in two, suboptimal noninvasive studies in one, and uncertainty of therapy despite good-quality noninvasive studies in 20 patients primarily with borderline stenoses and unclear symptoms. In 10 of these 30 patients (33%) management decisions were changed on the basis of angiogram results. Of the remaining 73 patients (71%) in whom the panel felt comfortable proceeding with operative or medical therapy without angiography, only one patient (1.4%) would have had management altered by results of angiography. MRA results concurred with duplex findings in 92% of studies, but did not alter management in any patient.

CONCLUSIONS

In patients with good-quality duplex images, focal atherosclerotic bifurcation disease, and clear clinical presentation, treatment decisions can be made without arteriography. In 30% of patients angiography is useful in clarifying decisionmaking. MRA is unlikely to influence management decisions and is thus rarely indicated.

Comparative analysis of percutaneous transluminal angioplasty and operation for renal revascularization

Contemporary patients requiring renal revascularization often have diffuse atherosclerosis, and increasingly undergo intervention for salvage of renal function rather than control of hypertension alone. Risk-benefit analyses and outcome data are difficult to obtain, since few reports have analyzed a modern, unselected series of consecutive patients subjected to renal revascularization by surgical as well as interventional techniques. We reviewed our 5-year experience with 76 consecutive renal revascularizations in 63 patients. Indications for intervention were hypertension and renal salvage, 60 percent (n = 38); hypertension, 24 percent (n = 15); renal salvage, 9.5 percent (n = 6); and other, 6.5 percent (n = 4). Ninety-four percent (n = 59) of patients had atherosclerotic occlusive disease of the renal arteries. Percutaneous transluminal angioplasty (PTA) was initially performed on 18 renal arteries in 16 patients, of whom 56 percent (n = 9) subsequently required surgical reconstruction. Fifty-eight surgical reconstructions were performed in 56 patients and consisted of aortorenal bypass (n = 27), aortorenal endarterectomy (n = 18), and extra-anatomic bypass (n = 13). Concomitant aortic replacement was required in 57 percent (n = 32) of patients. Preoperative risk factors and operative indications did not differ between the PTA and surgical reconstruction groups. Morbidity and mortality rates associated with PTA were 33 percent and 4.8 percent, respectively, while for surgical treatment the morbidity rate was 7 percent and the mortality rate 5.3 percent (P = NS). Functional improvement was achieved in 74 percent of surgically treated patients compared with 22 percent of PTA-treated patients (P < 0.01). Actuarial renal artery primary patency at 48 months was 81 percent for the surgery group and 17 percent for the PTA group (P < 0.01). Aortorenal bypass, endarterectomy, and extra-anatomic bypass were equally efficacious (P > 0.05). The results of surgical reconstruction are excellent, offering more durable patency and functional improvement than PTA, without increased risk. The operation should be tailored to fit the individual patient's disease, since the results of endarterectomy and bypass procedures are equivalent.

Aspiration pneumonia following surgically placed feeding tubes

BACKGROUND

The enteral route is preferred in surgical patients requiring nutritional support; however, controversy surrounds the choice of location of feeding tube placement. Although jejunostomy has been commonly accepted as superior to gastrostomy for long-term nutritional support because of an assumed lower risk of aspiration pneumonia, recent studies suggest that reevaluation of common practices of surgical tube placement is warranted.

PATIENTS AND METHODS

We conducted a retrospective chart review of gastrostomy and jejunostomy procedures from 1986 to 1993. Demographic information and complications related to the procedure were reviewed. Aspiration pneumonia was defined as respiratory symptoms, leukocytosis, and infiltrate on chest radiograph.

RESULTS

Sixty-nine gastrostomies and 86 jejunostomies were performed during the study period. Six patients were diagnosed with aspiration pneumonia; 2 cases of which occurred with jejunostomy and 4 cases occurred with gastrostomy (P = not significant).

CONCLUSIONS

There was no difference in rates of pulmonary aspiration or other complications between gastrostomy and jejunostomy. We suggest that when a surgically placed feeding tube is required, the determination of appropriate procedure be based on clinical factors such as the technical difficulty of the operation or long-term feeding goals.

Abdominal wall hernias in patients with abdominal aortic aneurysmal versus aortoiliac occlusive disease

BACKGROUND

This study was undertaken to determine the incidence of ventral incisional hernias (VIHs) and inguinal hernias (IHs) in patients with abdominal aortic aneurysmal (AAA) versus those with aortoiliac occlusive disease (AIOD).

PATIENTS AND METHODS

The medical records of 193 patients (128 with AAA and 65 with AIOD) who had undergone elective aortic reconstruction were reviewed to determine the number and location of abdominal wall hernias (AWHs).

RESULTS

Forty-one AWHs (28 IHs and 13 VIHs) were detected in patients with AAA compared to 13 (11 IHs and 2 VIHs) in patients with AIOD. There was a significantly greater incidence of VIHs in patients with AAA versus patients with AIOD (10% versus 3%, P < 0.05) and recurrent AWHs (28% versus 19%, P < 0.01), but not of IHs (22% versus 17%).

CONCLUSION

Patients with AAA have a higher incidence of VIHs and recurrent AWHs--without a corresponding increase in patient-related risk factors--than patients without aneurysm, suggesting that as yet unidentified etiologic factors may contribute to the development of AWHs in these patients.

Prospective evaluation of peripheral vascular disease in heart transplant recipients

PURPOSE

Retrospective reviews suggest that the progression of peripheral vascular disease (PVD) may be accelerated in heart transplant recipients. This study was undertaken to determine the incidence and to identify those risk factors that may be associated with the development or progression of PVD in these patients.

METHODS

Between January 1990 and December 1993 a prospective vascular screening protocol including abdominal ultrasonography, Doppler-derived ankel-brachial pressure indexes (ABI), and carotid artery duplex imaging was added to the routine preoperative and annual postoperative evaluation of 239 heart transplant recipients.

RESULTS

Thirty-one significant vascular lesions were detected in 10% (24 of 239) of patients 52 +/- 9 years of age at a mean of 3.2 years after transplant. The distribution of lesions included carotid artery stenosis (11), femoropopliteal occlusive disease (10), aortoiliac occlusive disease (five), aortic aneurysm (four), and renal artery stenosis in one patient. Revascularization procedures were performed in 12 (50%) patients (carotid endarterectomy (four), aortobifemoral bypass grafting (three), abdominal aortic aneurysm repair (two), transluminal angioplasty (two), splenorenal bypass (one), and femorotibial bypass grafting (one)). One patient with diabetes mellitus (DM) was found to have noncompressible vessels during pretransplant evaluation. An additional 26 patients (11%), seven with DM, had noncompressible vessels in the lower extremities during the follow-up period. Logistic regression analysis revealed that the development of posttransplant PVD was associated with smoking (p < 0.05) and ischemic cardiomyopathy as an indication for transplantation (p < 0.05). The development of noncompressible vessels was associated with younger age (p < 0.05) and the presence of diabetes (p < 0.05).

CONCLUSION

Posttransplant peripheral vascular disease occurred in 10% of heart transplant recipients and is associated with pretransplant ischemic cardiomyopathy and smoking. A previously unrecognized subgroup of patients who have noncompressible vessels after operation is described. If the long-term survival of the heart transplant recipient is to be improved, routine follow-up to identify and treat those patients at greater risk appears justified.

Clinical and CT evaluation of a new stretch polytetrafluoroethylene aortic graft

A new stretch polytetrafluoroethylene (PTFE) aortic graft became available for clinical use in early 1991. We prospectively evaluated our first 107 stretch aortic PTFE grafts by means of serial CT imaging and compared them with a cohort of concurrently placed Dacron grafts. Stretch PTFE requires no preclotting and is claimed to resist long-term dilation and conform well to anastomoses. Consecutive patients undergoing placement of stretch PTFE grafts were seen at least yearly. Within the first 2 years after implantation, contrast-enhanced CT scans of the abdomen and pelvis were obtained. Caliper measurements were made of the native arteries and the body and any limbs of the aortic grafts. Graft elongation was assessed by noting distortions from the normally circular or minimally ovoid configuration of the grafts on transverse CT images. Indications for grafting were elective repair of abdominal aortic aneurysm in 60 patients, aortoiliac occlusive disease in 31, both aneurysm and occlusive disease in eight, and ruptured abdominal aortic aneurysm in eight. The overall operative mortality rate was 6.5%. There were two early postoperative graft limb thromboses resulting from hypercoagulable states, and there was one graft infection. Mean follow-up was 14.1 months (range 1 to 34 months). CT scans were obtained from 61 patients with stretch PTFE grafts and 10 with concomitantly placed Dacron grafts. Ten patients had two or more postoperative CT scans. Primary stretch PTFE patency was 98% and secondary patency, 100%. There was significantly less dilation of both the graft body and limbs in the stretch PTFE group (body mean 16.5%, range 6.3% to 28.1%; limb mean 19.3%, range 10% to 43%) compared to the Dacron group (body mean 33%, range 22% to 78%; limb mean 62%, range 12.5% to 88.9%) (p < 0.01, unpaired t test).(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical treatment of symptomatic biliary stones in patients with cystic fibrosis

Patients with cystic fibrosis have a high incidence of cholelithiasis. However, few studies have addressed the operative therapy for cholelithiasis in this group of patients with poor pulmonary function. We reviewed six patients with cystic fibrosis who were treated for symptomatic biliary stones. Five patients underwent cholecystectomy for chronic cholecystitis. One patient with extremely poor pulmonary status presented with choledocholithiasis and cholangitis, which was successfully treated with endoscopic sphincterotomy followed by ursodeoxycholic acid therapy. Five of these six patients had significant relief of their symptoms. One patient never recovered completely from the operation and eventually died from continued pulmonary deterioration. We conclude that in patients with cystic fibrosis and symptomatic biliary stones, careful attention to pulmonary care can afford safe, elective cholecystectomy. More conservative treatment is indicated in patients with marginal pulmonary reserve.

Application of computed tomography for surveillance of aortic grafts

BACKGROUND

This study was undertaken to assess the application of computed tomography (CT) for surveillance of aortic grafts.

METHODS

Demographics, operative technique, and graft type and size at the time of implantation of aortic grafts in 178 patients were recorded. CT measurements of graft diameters were made with calipers. Data were analyzed by analysis of variance, multiple regression, and chi-squared methods.

RESULTS

One hundred twenty-eight (72%) bifurcated grafts and 50 (28%) tube grafts were placed for aneurysmal disease (49%), aortoiliac occlusive disease (47%), ruptured aneurysm (2.3%), anastomotic aneurysm (1%), and graft aneurysm (0.6%). Mean implant time was 43.3 +/- 3.2 months. A total of 143 Dacron prostheses (74 woven, 69 knitted) and 35 polytetrafluoroethylene prostheses were placed. Mean percentage dilation was 49.2 +/- 4.0 for knitted prostheses, 28.5 +/- 3.0 for woven prostheses, and 20.6 +/- 1.9 for polytetrafluoroethylene prostheses compared with the graft implant size. A significant correlation was seen between graft dilation (more than 50%) and graft construction with knitted prostheses (p < 0.01, Tukey's range test). Complications detected by CT occurred in 24 (13.5%) patients including supragraft aneurysms (seven), distal anastomotic aneurysms (five), proximal anastomotic aneurysms (three), graft infections (two), perigraft fluid collections (two), graft aneurysm with thrombus and distal embolization (two), and nonvascular complications (three).

CONCLUSIONS

CT is a useful modality for postoperative imaging of aortic prostheses. Routine surveillance may detect complications before they become clinically apparent.

Distinguishing carotid artery pseudo-occlusion with color-flow Doppler

BACKGROUND AND PURPOSE

This study was undertaken to determine the impact of color-flow Doppler on the accuracy of noninvasive carotid imaging for distinguishing an internal carotid artery pseudo-occlusion (string sign) from a complete occlusion.

METHODS

From January 1985 to January 1994, review of noninvasive vascular studies, arteriograms, and operative reports of 26 consecutive patients undergoing 27 carotid endarterectomies for carotid pseudo-occlusion was performed. Further review was conducted of all patients identified with carotid occlusion by noninvasive testing who underwent confirmatory arteriography during the same interval.

RESULTS

Conventional gray-scale duplex scanning (January 1985 to December 1989) correctly identified 3 of 11 (27%) pseudo-occluded internal carotid arteries compared with 15 of 16 (94%) internal carotid artery pseudo-occlusions correctly identified by color-flow Doppler (January 1990 to June 1994) (P < .01). Similarly, carotid occlusion was more accurately identified by color-flow Doppler (33 of 33, 100%) compared with gray-scale duplex scanning (19 of 27, 90%) (P < .01).

CONCLUSIONS

The addition of color-flow Doppler to the duplex evaluation of the extracranial carotid circulation improves the accuracy of distinguishing carotid pseudo-occlusion from the occluded internal carotid artery and may obviate the need for arteriography to identify patients with this critical level of carotid stenosis.

MR angiography of the foot and ankle

To better understand the use of magnetic resonance angiography (MRA) in evaluating peripheral vascular disease, the authors studied arteries in the foot and ankle. Twenty patients with arterial occlusive disease of the lower extremity were studied with two-dimensional time-of-flight MRA, and the results were compared with those of 10 conventional x-ray arteriograms, four digital subtraction arteriograms, and three intraoperative arteriograms. The studies were reviewed and rated by three radiologists blinded to the patients' clinical history. Also, the first 16 patients were examined with MRA before and after intravenous injection of gadopentetate dimeglumine. The mean confidence levels for the reviewers' interpretations of the MRA studies were significantly higher than those for the conventional arteriograms for the medial plantar, lateral plantar, and plantar arch arteries of the feet (P < or = .005). Postcontrast MRA images were inferior to precontrast images because of overlapping of veins and arteries. Time-of-flight MRA without gadolinium can serve as a useful complementary study for evaluating patients with peripheral vascular disease in the foot and ankle.

Cellular origin and rate of endothelial cell coverage of PTFE grafts

To determine the origin, cell type present, and rate of endothelial cell coverage of PTFE grafts, 5-cm segments of 4-mm-diameter, 60-microns PTFE grafts were implanted end-to-end bilaterally in the carotid arteries of greyhound dogs. An external jugular vein wrap was applied to the outer surface of one of the PTFE grafts; the contralateral PTFE graft, which was unwrapped, served as its control. Two dogs each were sacrificed at 3, 5, 7, 14, 21, 28, and 35 days postimplantation. Anastomotic endothelial ingrowth was analyzed using scanning electron microscopy. Microvessel ingrowth was documented in longitudinal H&E sections. Cell identity was established by immunohistochemistry with factor VIII antibody, Ulex europaes, leukocyte common antigen, and antibodies to alpha-actin, desmin, vimentin, and basic fibroblast growth factor. All grafts were patent at the time of harvest. Endothelial cell migration from the native artery adjacent to the anastomosis commenced at 7 days, extended to 5 mm beyond the proximal and distal anastomoses by 14 days and to 1.0 cm by 35 days. Endothelialization of the mid-portion of the wrapped grafts occurred via microvessel ingrowth, a process which began at 7 days. Microvessels reached the luminal surface by 28 days and an endothelial cell monolayer was established by 35 days. Wrapping the external surface of the graft with vein increased the rate of graft healing. Basic fibroblast growth factor was detectable by immunohistochemistry at the vein wrap-graft interface in the first 14 days.

Contraindications and complications of laparoscopic cholecystectomy

Laparoscopic cholecystectomy is a commonly performed procedure for the removal of symptomatic gallstones. Compared with open cholecystectomy, laparoscopic cholecystectomy is associated with less postoperative pain, earlier discharge from the hospital and a more rapid recovery. However, there are specific contraindications to the procedure, including empyema of the gallbladder, gangrenous cholecystitis, coagulopathy, portal hypertension and peritonitis. Complications from laparoscopic cholecystectomy include common duct injury, bleeding, bile leakage and wound infection. An understanding of these issues allows the family physician to more appropriately select patients for laparoscopic removal of the gallbladder.

Stereotactic fine-needle aspiration cytology of nonpalpable breast lesions: an analysis of 258 consecutive aspirates

BACKGROUND

The role of stereotactic fine-needle aspiration cytology (SFNAC) in the diagnosis of nonpalpable breast lesions is poorly defined.

PATIENTS AND METHODS

Data were prospectively collected from 225 consecutive patients with nonpalpable breast lesions who had aspiration cytology followed by immediate surgical excision.

RESULTS

Between 1988 and 1993, 258 such procedures were performed. The results of 84 (33%) were interpreted as benign, 84 (33%) as atypical, 28 (11%) as suspicious for malignancy, and 49 (19%) as malignant. In all, 88 (34%) surgical specimens were malignant. SFNAC had an 80% sensitivity, a 96% specificity, a 91% positive predictive value, and an 89% negative predictive value. There were 18 false-negative and 7 false-positive aspirates.

CONCLUSIONS

SFNAC for diagnosing nonpalpable breast lesions is moderately sensitive and highly specific, and has a high positive and negative predictive value. In conjunction with mammography and clinical assessment, the procedure is useful for determining which patients with nonpalpable breast lesions may require surgical biopsy.