In vivo quantification of the apical fixation forces of different mitral valved stent designs in the beating heart.

The aim of this study was the quantification of the apical fixation forces of mitral valved stents for the first time. A test set-up was developed to measure the forces acting on the apical fixation of mitral valved stents. Twenty pigs received a self-expanding valved stent in the mitral position via a transapical approach in an off-pump procedure. Following stent deployment in the beating heart, the apical fixation forces were recorded following a standardized protocol and normalized. The apical fixation force of two different valved stent designs (AP: sole apical fixation, n = 10; SA: additional sub-annular fixation, n = 10) was compared to quantify the impact of the design change. Force measurement was successfully conducted in 18 of 20 animals (design AP: n = 10; design SA: n = 8). Evaluation showed higher mean forces and amplitude in the group with sole apical fixation (p = 0.046; Table 1). The impact of the additional sub-annular fixation was shown by a significant reduction of the force acting upon the apex of the heart. Quantification of these in vivo forces provides important information about the impact of different stent designs and might provide an objective parameter for stent performance evaluation in clinical application.

Transapical mitral valve implantation: the Lutter valve.

  The development of transcatheter techniques for treatment of severe mitral valve regurgitation in the beating heart is focus of recent research. An off-pump treatment technique poses great benefits, particularly for multimorbid patients, often being non-compliant to the gold standard treatment, being open heart surgery with use of a cardiopulmonary bypass. Thereto, two approaches are being followed: transcatheter valve repair and transcatheterimplantation of a valved stent into the native mitral valve annulus. A valved stent has to provide safe and secure fixation within the high pressure system of the left heart. One of the main challenges in the development of such a valved stent is the complex anatomy of the mitral valve, with no clearly defined structures for device anchorage. Our group has developed a self-expanding nitinolvalved stent for transapical implantation in the beating heart. During the development process of thevalved stent, different design iterations were conducted to decrease the risk of paravalvular leakages, to enhance the reproducibility and to improve the overall stent performance. This article reviews the major milestones passedin the development process of our mitral valved stent and advances achieved withinthe last years. Multiple design iterations lead to a prototype providing secure stent deployment, hig h reproducibility, low paravalvular leakages and only mild stent deformation in the beating heart. In future, further long-term in vivo trials have to be conducted before attempting the step towards clinical application of this novel device.

Current smoking among young adolescents: assessing school based contextual norms.

OBJECTIVE: To extend research on the relation of school based contextual norms to current smoking among adolescents by using three analytic techniques to test for contextual effects. It was hypothesised that significant contextual effects would be found in all three models, but that the strength of these effects would vary by the statistical rigor of the model. DESIGN: Three separate analytic approaches were conducted on baseline self report student survey data from a larger study to test the relation between school level perceived peer tobacco use and individual current smoking status. PARTICIPANTS: A representative sample of 5399 sixth through eighth grade students in 14 midwestern middle schools completed the survey. All enrolled sixth through eighth grade students were eligible to participate in the survey. The student participation rate was 91.4% for the entire sample, and did not differ significantly between the schools (range 82-100%). MAIN OUTCOME MEASURE: Thirty day cigarette smoking prevalence. RESULTS: A level 2 only model based on aggregated individual responses indicated that students in schools with higher average reported peer tobacco use were more likely to be current smokers than students in schools with lower average peer tobacco use. Using a level 1 only model based on individual responses indicated that the effect of school level perceived peer tobacco use on current smoking was significant when individual perceived peer tobacco use was excluded from the model but was non-significant when individual perceived peer tobacco use was added to the model. A multilevel model also indicated that the effect of school level perceived peer tobacco use on current smoking was not significant when individual perceived peer tobacco use was added to the model. CONCLUSION: The analytic approach used to examine contextual effects using individuals' reports of peer tobacco use norms that were aggregated to obtain a context measure of the school norms may produce statistical artefacts that distort the association of the school context in general, and peer tobacco use norms in particular, with increased risk for current smoking beyond the risk associated with individual factors.

Eliminating invalid self-report survey data.

A sample of 6,370 students in Grades 6 to 8 completed a questionnaire on their attitudes and use of alcohol, tobacco, and other drugs. A subsample showed questionable data based on three criteria: missing responses, invalid responses, and inconsistent responses. Analysis indicated that this subsample was significantly different from the main group on demographic variables and self-reported life-time tobacco use. Results support efforts to identify and eliminate invalid data.

Do participation rates change when active consent procedures replace passive consent.

Researchers face considerable ambiguity and controversy regarding the issue of informed consent. Decisions about consent procedures can affect study participation rates and prevalence estimates among specific populations. Changing from passive to active parental consent procedures was examined in a case study with an anonymous survey of sixth- through eighth-grade students' substance use. Four types of procedures for obtaining parental consent were examined. Results suggest that certain types of consent procedures can yield high levels of participation. This study also demonstrates that low participation rates with some active consent procedures can cause biases in sample characteristics and outcome data.

The relationship between youth tobacco control enforcement and crime rates in a midwestern county.

The crime rate in 29 counties was compared with the level of enforcement of laws restricting youth purchases. There was a linear relationship between crime rate and enforcement. Communities with the highest enforcement policies had the lowest crime rates.

Circumferential hymen elasticity. A marker of physiologic maturity.

OBJECTIVE: To study the relationship between anatomic changes in the peripubertal female and sex hormonal maturation. STUDY DESIGN: Medical records were reviewed on virginal females whose first gynecologic examination occurred between ages 9 and 20 and who were examined at least twice by the same gynecologist. Speculum sizes at each visit were surrogate measures of circumferential hymenal elasticity, the anatomic change of interest. RESULTS: Mean ages at the two visits for the 35 patients were 14.6 and 16.7 years, respectively, with substantial overlap in ages between visits. Average Tanner breast and pubic hair stages and speculum sizes were greater at the second visit (P < .001). At first visit, age, Tanner breast and pubic hair stages, and time elapsed from menarche, thelarche and pubarche correlated positively with larger speculum sizes (P < .10). Change in speculum size between visits was associated with younger age and lower Tanner pubic hair stages at first visit and with increases between visits in age, body mass index and Tanner pubic hair stages. Larger changes were associated with shorter elapsed time between the first visit and menarche, thelarche and pubarche. CONCLUSION: Circumferential hymenal elasticity increases during adolescence. This anatomic change, the surrogate measure of which is specula diameter, can be used along with Tanner staging as a measure of physiologic maturity in adolescent women.

Implementing means restriction education in urban EDs.

This study evaluated the impact of a mail information campaign on emergency department (ED) professionals' knowledge about the lethal role of firearms in suicide, knowledge of appropriate strategies for warning caregivers of adolescents who have attempted suicide about firearms, and practices with respect to the delivery of such warnings. Responses obtained from physicians and nurses working in ED sites within the targeted city (Chicago) were compared with responses from ED professionals employed in a comparison city (Detroit). In Chicago, the percentage of respondents recommending firearm removal strategies increased from 60% at pretest to 76% at posttest. Individual reports of caregiver warnings per adolescent suicide exposure showed a significant decline in Chicago and a marginally significant decline in Detroit. Gains in knowledge about firearm warning strategies persisted in multivariate analyses controlling for subject demographic characteristics. The pattern of results suggests that the intervention may have effected changes in knowledge while having little impact on behavior. More intensive, interactive educational strategies may be needed to effect behavioral changes among ED professionals.

Long-term intravaginal presence of foreign bodies in children. A preliminary study.

The similar clinical features of childhood sexual abuse, isolated premature menarche and intravaginal foreign objects prompted a preliminary study of the anatomic features of intravaginal foreign objects in premenarchal females.

The genital examination of the infant through adolescence.

The genital examination of the young female is a relatively new procedure for many clinicians. It was not felt important until physicians became involved with the examination of survivors of childhood sexual abuse; from these examinations it is apparent that young females also have a broad array of genital conditions which need clinical evaluation and intervention. This review of the recent literature on the techniques employed by a variety of clinicians demonstrates the limitations placed on our knowledge of pediatric and adolescent gynecologic conditions by technical and psychosocial parameters.

Acute genital injury in the prepubertal girl.

In an effort to develop guidelines for the management of acute genital injuries in prepubertal girls, we categorized 32 cases by the object that allegedly caused the injury: straddle injuries, nonpenetrating injuries, penetrating injuries, and torque injuries. Using these categories and the anatomic features of symmetry and/or hymenal transection, we determined that the most dangerous injuries were the penetrating injuries that were symmetric and transected the hymen; in this series these were all the result of sexual assault. Future studies are needed to determine if these unique injuries can be managed with less physical and psychosocial trauma to the young patient.

Prepubertal vulvovaginopathies.

The vast majority of prepubertal gynecologic problems fall into three categories. The most serious category includes those "things that bleed": sarcoma botryoides, trauma (including sexual abuse), vaginal foreign objects, condylomata, urethral prolapse, and single organism vaginitis. Very rarely, the clinician will see precocious menarche, metastatic Crohn's disease, vascular vulvar lesions, and factitious cases. The next category contains entities that have an abnormal appearance: ambiguous genitalia, periurethral cysts of the newborn, hymenal variants, and agglutination of the labia and vulva. Rarely, an underlying skin disorder such as lichen sclerosus, seborrhea, or atopic vulvitis will be seen. The last and most bothersome category, distinguished by its symptoms of pruritus and discharge, includes the most common types of vulvovaginitis.

Prevalence of cytomegalovirus antibody in subjects between the ages of 6 and 22 years.

We determined the prevalence of antibody to cytomegalovirus (CMV) in three groups between 1985 and 1987. Group I consisted of 511 subjects 6-22 y old, group II consisted of 920 subjects 18-21 y old, and group III of 113 subjects 18-22 y old. The overall prevalence of antibody in these three groups was 34%, 24%, and 28%, respectively. Prevalence of antibody in white subjects (24%, 21%, and 24%, respectively) was significantly lower than that in nonwhite subjects. In group I, there was no increase in prevalence with age in white subjects, but the percentage of individuals with antibody increased with age among nonwhite subjects. It is of obvious concern that a large proportion of white women entering childbearing years lack CMV antibody.

Child abuse and infections.

Although our understanding of sexually transmitted diseases in children is rudimentary, we cannot ignore the long-term consequences that the pathophysiologic process can have. This article reviews the role of the health care provider to the sexually abused child and discusses the documentation and treatment of sexually transmitted diseases.

Ultrasound examination of adolescent females with lower abdominal pain.

We evaluated pelvic ultrasound examination in adolescent females as an aid in the diagnosis of acute and chronic lower abdominal pain resulting from suspected gynecologic disease. Of 41 subjects, 35 (85.4%) had a final diagnosis of a gynecologic disorder. Pelvic ultrasound examination was positive in 19 of 35 (54.3%). Ten positive tests had relatively specific findings that supported (seven) or helped change (three) the initial clinical diagnosis. Nine positive tests had nonspecific findings that were consistent with (six) or helped change (three) the initial diagnosis. Twenty-one negative tests helped change the initial diagnosis (13); ruled out complications of acute salpingitis (five); or discriminated between alternative diagnoses (three). One test was falsely positive. Ultrasonography was most clearly cost-effective when surgery was being considered. We conclude that pelvic ultrasound examination may be a useful diagnostic adjunct in this type of adolescent patient.