Short-term patency and safety of an expanded polytetrafluoroethylene encapsulated endoluminal device at the venous anastomosis of a canine arteriovenous graft model.

PURPOSE: To determine the safety and short-term patency of a polytetrafluoroethylene (PTFE)-encapsulated carbon-lined endoluminal device (ED) deployed across the venous anastomosis of arteriovenous conduits. MATERIALS AND METHODS: Arteriovenous grafts (n = 16) were created between femoral arteries and veins in eight female canines and allowed to mature 30 days +/- 5 (SD). Five were excluded before implantation because of thrombosis or intragraft stenosis. Deployment was conducted in the remaining 11 anastomoses. Fistulography and intravascular ultrasound (IVUS) were performed before and after the procedure and 1 month postimplantation. Stent migration, apposition, and stenosis were evaluated. The angle of the anastomosis was compared before and after deployment and at follow-up. Mural thrombus thickness, percentage of surface covering, and percentage of endothelialization within the device were measured histologically. RESULTS: There was no significant migration. By explant, all devices were completely apposed. Stenosis occurred in three of nine grafts. The angle of the venous anastomosis decreased by 29.5 degrees (posteroanterior) and 32.4 degrees (oblique) after ED deployment. There was a further decrease of 6.1 degrees (posteroanterior) and 3.2 degrees (oblique) during the 4-week follow-up period. Hemostasis was difficult to achieve in this animal model. Five required more than 1 hour to achieve hemostasis manually. Six in three animals were closed with a Perclose device, achieving immediate hemostasis; however, three (one in each animal) re-bled intermittently 2 weeks after implantation for an average of 9.3 days. The puncture site of each graft that bled was radiographically shown abnormal. CONCLUSION: The ED can be deployed without stent migration and is completely apposed and patent after 4 weeks. Although bleeding was a problem with this animal model, delayed bleeding complications associated with puncture site abnormalities were seen only in grafts closed with a percutaneous suturing device.

Brachytherapy for the prevention of stenosis in a canine hemodialysis graft model: preliminary observations.

PURPOSE: To determine whether gamma brachytherapy can prevent in-stent stenosis in hemodialysis grafts. MATERIALS AND METHODS: Six-millimeter polytetrafluoroethylene arteriovenous grafts were created bilaterally in six dogs. After 1 month, Wallstents spanning the venous anastomosis were placed to accelerate restenosis. Gamma irradiation (12 Gy) was delivered endoluminally to one of the two grafts by using an iridium 192 source; thus, each animal served as its own control. Fistulography was performed monthly for 10 months or until graft thrombosis, with measurement of stenosis at each time point. At the conclusion of the study period, the treated area was examined histologically, and a computer model was used to calculate the volume of intimal hyperplasia. RESULTS: Delayed stent migration resulted in exclusion of one dog. In the remaining five dogs; maximum stenosis across all time intervals was less for the treated side (P < .04), and the volume of intimal hyperplasia was less for the treated side (P < .045). In one animal studied at 1 year, this trend reversed in terms of percentage stenosis but not total neointimal volume. CONCLUSION: Brachytherapy with 192Ir (gamma) delivered at the time of stent placement reduces restenosis in this hemodialysis graft model, but, depending on the parameter evaluated (stenosis vs total volume of neointima), the benefit may wane or even reverse with time.

Preclinical in vivo testing of a rotational mechanical thrombolytic device.

PURPOSE: To establish the safety and efficacy of the Arrow Trerotola mechanical percutaneous thrombolytic device (PTD) for restoring patency of thrombosed hemodialysis grafts. MATERIALS AND METHODS: The hindlimb model of dialysis grafts was created in six dogs. Animals had either unilateral (n = 4) or bilateral (n = 2) polytetrafluoroethylene grafts, totaling eight grafts. Grafts were deliberately clotted 48 hours before thrombolysis. Thrombolysis was performed with five different versions of the PTD constructed of stainless steel (n = 12) or nitinol (n = 26) and rotated with use of a hand-held motor drive. After thrombolysis, fistulography was performed. RESULTS: Thirty-eight procedures were performed with the PTD, with 100% success. Thirty-day patency, evaluated in a subset of 15 procedures, was 100%. Complications included a single arterial embolus (2.6%) and eight device breakages (21%, all but two with the stainless steel version); none had any clinical consequences. A final modification of the nitinol device yielded 11 consecutive procedures without further breakage. No residual thrombus occurred in any procedure. Pathologic examination showed no significant injury to the vessels or neointima. CONCLUSION: The PTD is highly effective for mechanical thrombolysis in an animal model of clotted dialysis grafts. Based on this animal model, the device appears safe in its final modified form.

Pulmonary emboli from pulse-spray and mechanical thrombolysis: evaluation with an animal dialysis-graft model.

PURPOSE: To compare pulmonary emboli resulting from pulse-spray pharmacomechanical thrombolysis (PSPMT) and mechanical thrombolysis performed to declot dialysis-access grafts. MATERIALS AND METHODS: Polytetrafluoroethylene arteriovenous shunts were created in eight dogs and were deliberately clotted at monthly intervals. Animals were randomly assigned to treatment with pulse-spray urokinase thrombolysis or a low-speed rotational percutaneous thrombolytic device. Perfusion imaging, pulmonary-artery pressure measurements, and pulmonary arteriography were performed before and after each procedure. RESULTS: A total of 22 procedures were performed (11 PSPMT and 11 mechanical thrombolysis). Declotting was successful in all procedures, with 100% 30-day patency. Segmental defects were seen on perfusion images after 10 (91%) of 11 PSPMT procedures and two (18%) of 11 mechanical thrombolysis procedures (P < .002). Transient increases in pulmonary-artery pressure occurred in the PSPMT group. Complete resolution of emboli and return to baseline pressures were seen in all cases, even after multiple (up to four) procedures in the same animal. There was no histologic evidence of pulmonary infarction in either group. CONCLUSION: The percutaneous thrombolytic device is effective for declotting dialysis grafts in dogs and results in statistically significantly fewer pulmonary emboli compared with PSPMT.

Presenting problems of substance abusers in treatment: implications for service delivery and attrition.

This study used the Addiction Severity Index (ASI) to identify the various problems substance abuse clients present when seeking treatment at a Department of Veterans Affairs Medical Center. The sample was 98% male and 73% African-American, with a mean age of 37 years. Cluster analysis was used to identify commonalities and divergences in self-reported employment, legal, family, substance abuse, psychological, and medical problems. Four distinct clusters emerged, each of which could be characterized by a dysfunctional pattern. The utility of this approach in designing treatment regimens, addressing client problems in addition to their substance abuse, increasing client satisfaction with service provided, and decreasing treatment attrition is discussed.

High-risk behaviors for transmission of syphilis and human immunodeficiency virus among crack cocaine-using women. A case study from the Midwest.

This study examines the drug use patterns, sexual practices, condom use, knowledge and attitudes toward sexually transmitted diseases (STD)s and AIDS, and seroprevalence of human immunodeficiency virus (HIV) and syphilis among women who use crack in Dayton, Ohio. In 1990, two indigenous outreach workers recruited 150 participants who were not in drug treatment programs, who were 18 years of age or older, and had used crack in the previous 3 months. Structured interviews revealed that 90% of the sample were black, 78% used crack "daily," 93% had multiple sexual partners, and 49% had 10 or more male sexual partners in the last 3 months. A majority (67%) of the women felt they were in need of drug treatment. No reactive syphilis serologies were detected in 138 serum samples; 2 women (1.4%) were HIV seropositive. This case study provides insight into the high-risk sexual behaviors of crack users in a medium-sized, midwestern city. The study demonstrates the value of indigenous outreach prevention and STD screening initiatives in reaching this segment of our society, which has a high risk of acquiring STDs.

Exchanging sex for crack-cocaine: a comparison of women from rural and urban communities.

Studies of the HIV risks of crack-cocaine using women have focused on those living in the inner city, urban areas of the country. However, reports indicate that the rates of syphilis and HIV infection have shown greater increases in rural areas than in urban ones. This paper reports the findings of a comparative study of 60 female crack-cocaine users, 25 from rural southeast Georgia and 35 from Miami, Florida, to determine their drug using and sexual practices, as well as their knowledge about AIDS and HIV transmission. Their patterns of initial and continuous drug use were similar, as were their sexual practices. However, the Miami women were more likely to have had a greater number of sexual partners than the Georgia women. Both groups were knowledgeable about AIDS and the transmission of HIV, yet all participated in activities that put them at high risk for HIV infection and transmission. Some 12 percent of the 60 respondents reported testing positive for HIV. The study suggests that at least within these populations, there are few differences between rural and urban crack using women in terms of their crack use, sexual practices, and potential for HIV infection and transmission.

HIV infection and risk behaviors among intravenous drug users in low seroprevalence areas in the Midwest.

We studied behavioral factors that place intravenous drug users at risk for the acquisition and transmission of the human immunodeficiency virus (HIV) in a sample of 855 individuals not in drug treatment, living in central and southwestern Ohio. The HIV seropositivity rate for the sample was 1.5%. Three factors were significantly related to HIV infection: homeless shelter residence (odds ratio [OR] = 7.7, 95% confidence interval (CI) = 3.0-20.0), travel to northeastern HIV hyperendemic areas (OR = 5.2, 95% CI = 1.8-15.4), and recent male homosexual or bisexual behavior (OR = 11.2, 95% CI = 2.9-43.9).

Predictor variables of adolescent drinking.

A survey was conducted to determine which socio-cultural and psychosocial variables had the ability to discriminate adolescent drinking behavior at four different age groups. A total of 3,017 sixth, eighth, tenth, and twelfth grade students in the Southeast participated in the study. Those students who were classified as moderate to heavy drinkers were more likely to be White, male, had higher scores on an alcohol knowledge test, were more liberal in their attitudes toward alcohol use, drank at an earlier age, and had friends who drank. When all predictor variables were considered as a group, the two most predominant characteristics for explaining student drinking behavior were peer behavior and attitudes toward alcohol. Parental drinking behaviors were significant for the younger students, but compared to the peer and attitude variables, their contributions to group separation were minor. Efforts to curb moderate or heavy drinking among adolescents should focus on the peer influences of adolescent drinking and related risk factors associated with problem drinking.

Profile of an adolescent problem drinker.

A study was conducted to determine what sociocultural and demographic variables can be used to identify potential problem drinkers among adolescents in middle school and high school. Three thousand seventeen students were administered an in-depth questionnaire regarding their knowledge, attitudes, and behavior toward the use of alcohol. Twenty schools in six school districts in the two-state area of Georgia and South Carolina participated in the study. A number of analyses indicated that the student heavy drinker was most typically male, white, and between the ages of 14 and 15 years with an above average knowledge about alcohol and liberal attitudes toward alcohol use. The adolescent heavy drinker is more likely to have parents and best friends who are heavy drinkers, to have had his first encounter with alcohol at an early age, to drink with friends his own age, and to feel that almost all of his friends drink. Results of this study can be used by family physicians in the management of potential alcohol abusers. Early recognition and intervention by the family physician may help to reduce the alarming number of adolescents who are struggling with problems related to alcohol.

A profile and prediction study of problem drinking among first-year medical students.

A study was conducted to determine to what extent first-year medical students are engaged in alcohol use and if specific sociocultural and self-reported behavior characteristics can be used to develop a profile and to predict potential problem drinkers. Four geographically distinct medical schools participated in the study, with a total of 341 students completing a questionnaire regarding current alcohol use and other risk-taking behaviors. Chi-square analyses, analyses of variance, and a discriminant analysis indicated that there is a high occurrence of frequent and heavy drinking among first-year medical students. Potential problem drinkers appear to be White males whose fathers are heavy drinkers. They seem prone to a nonpassive life-style and attend church infrequently. Prevention/intervention programs in medical school can utilize these results to identify high-risk individuals early in their medical career and target them for counseling.

Alcohol and adolescents. Knowledge, attitudes, and behavior.

Students (n = 3017) from the 6th, 8th, 10th, and 12th grades in six school districts throughout Georgia and South Carolina completed a questionnaire to determine their knowledge, attitudes, and behavior regarding alcohol use. Results suggest that knowledge, attitudes, and behavior are significantly correlated. Two distinct attitudes were discovered: acceptable use of alcohol and unacceptable uses of alcohol, and these interacted with knowledge and behavior in different ways. Students who reported school as their major source of information about alcohol were more knowledgeable and had the most conservative attitudes toward unacceptable use of alcohol (p less than 0.001). White students scored higher on the knowledge test and had more liberal attitudes than minority students (p less than 0.001). Females were more conservative than males (p 0.001), and older students had more liberal attitudes (p less than 0.001). Our results suggest that efforts to educate youth about alcohol should incorporate acceptable uses as well as the negative aspects of drinking.

Evaluation of In-111 labeled lymphocytes in an acute rejection model.

Four days after surgery, canine renal allografts were studied with 290-500 microCi of In-111/10(8) lymphocytes. All transplants were visualized, implying that it may not be necessary to harvest large numbers of lymphocytes from immunosuppressed patients. On the day of renal transplant, a second set of dogs were injected with 80-150 microCi of In-111/10(8) lymphocytes. No delayed visualization could be seen 2-4 days later when rejection commenced. Cellular damage, even at this lower level of labeling, may require injection of labeled lymphocytes after the onset of the rejection process in order to visualize the rejection organ.