Control of intravascular catheters using an array of active steering coils.

PURPOSE: To extend the concept of deflecting the tip of a catheter with the magnetic force created in an MRI system through the use of an array of independently controllable steering coils located in the catheter tip, and to present methods for visualization of the catheter and/or surrounding areas while the catheter is deflected. METHODS: An array of steering coils made of 42-gauge wire was built over a 2.5 Fr (0.83 mm) fiber braided microcatheter. Two of the coils were 70 turn axial coils separated by 1 cm, and the third was a 15-turn square side coil that was 2 x 4 mm2. Each coil was driven independently by a pulse width modulation (PWM) current source controlled by a microprocessor that received commands from a MATLAB routine that dynamically set current amplitude and direction for each coil. The catheter was immersed in a water phantom containing 1% Gd-DTPA that was placed at the isocenter of a 1.5 T MRI scanner. Deflections of the catheter tip were measured from image-based data obtained with a real-time radio frequency (RF) spoiled gradient echo sequence (GRE). The small local magnetic fields generated by the steering coils were exploited to generate a hyperintense signal at the catheter tip by using a modified GRE sequence that did not include slice-select rewinding gradients. Imaging and excitation modes were implemented by synchronizing the excitation of the steering coil array with the scanner by ensuring that no current was driven through the coils during the data acquisition window; this allowed visualization of the surrounding tissue while not affecting the desired catheter position. RESULTS: Deflections as large as 2.5 cm were measured when exciting the steering coils sequentially with a 100 mA maximum current per coil. When exciting a single axial coil, the deflection was half this value with 30% higher current. A hyperintense catheter tip useful for catheter tracking was obtained by imaging with the modified GRE sequence. Clear visualization of the areas surrounding the catheter was obtained by using the excitation and imaging mode even with a repetition time (TR) as small as 10 ms. CONCLUSIONS: A new system for catheter steering is presented that allows large deflections through the use of an integrated array of steering coils. Additionally, two imaging techniques for tracking the catheter tip and visualization of surrounding areas, without interference from the active catheter, were shown. Together the demonstrated steerable catheter, control system and the imaging techniques will ultimately contribute to the development of a steerable system for interventional MRI procedures.

Development of gold standard ion-selective electrode-based methods for fluoride analysis.

BACKGROUND/AIMS: Currently available techniques for fluoride analysis are not standardized. Therefore, this study was designed to develop standardized methods for analyzing fluoride in biological and nonbiological samples used for dental research. METHODS: A group of nine laboratories analyzed a set of standardized samples for fluoride concentration using their own methods. The group then reviewed existing analytical techniques for fluoride analysis, identified inconsistencies in the use of these techniques and conducted testing to resolve differences. Based on the results of the testing undertaken to define the best approaches for the analysis, the group developed recommendations for direct and microdiffusion methods using the fluoride ion-selective electrode. RESULTS: Initial results demonstrated that there was no consensus regarding the choice of analytical techniques for different types of samples. Although for several types of samples, the results of the fluoride analyses were similar among some laboratories, greater differences were observed for saliva, food and beverage samples. In spite of these initial differences, precise and true values of fluoride concentration, as well as smaller differences between laboratories, were obtained once the standardized methodologies were used. Intraclass correlation coefficients ranged from 0.90 to 0.93, for the analysis of a certified reference material, using the standardized methodologies. CONCLUSION: The results of this study demonstrate that the development and use of standardized protocols for F analysis significantly decreased differences among laboratories and resulted in more precise and true values.

Comparative efficacy of colestipol and clofibrate in type IIa hyperlipoproteinemia.

A multiclinic study was performed comparing colestipol hydrochloride, clofibrate, and placebo in 245 patients with type IIa hyperlipoproteinemia. Eighty-five subjects took colestipol hydrochloride in progressive doses of 15, 20, and 30 g/day; 87 took 2.0 g/day of clofibrate; and 73 took placebo over the six months of study. Colestipol lowered total cholesterol level 20.9% in comparison with clofibrate (14.6%) (statistically significant at months 3, 5, and 6), and lowered low-density lipoprotein cholesterol level 28.8% in comparison with clofibrate (14.8%) (significant at months 2, 4, and 6, all times measured). High-density lipoprotein cholesterol level remained unchanged in all groups. Clofibrate lowered total triglyceride levels 22.5%, compared with an increase of 12.5% in the colestipol group and 11.1% in the placebo group (significant at all time intervals). Colestipol was more effective than clofibrate in lowering the cholesterol fractions associated with increased cardiovascular risk.

Pedal symphalangism in modern American and Japanese skeletons.

Pedal symphalangism is a surprisingly common heritable trait of the human foot. In individuals exhibiting the trait, the joint between the intermediate and distal phalanges of one or more lateral toes never develops, resulting in toes with two phalanges rather than three. This study was undertaken to explore variation in the frequency of pedal symphalangism among groups with widely different geographic ancestry, and to consider the applicability of this trait to skeletal biological distance studies. A total of 460 Euro-American, 191 African-American and 99 Japanese skeletons were examined for presence of pedal symphalangism. The American individuals date to the first half of the 20th c, while the Japanese individuals date to the late 19th and early 20th c. Although the country of ancestry is unknown for most of the American individuals, the Euro-Americans appear to be largely northern European, with roots in Germany, Ireland and Scandinavia, while the African-Americans are primarily descendants of slaves with roots in west African countries such as Nigeria, Benin, Togo, Ghana and Sierra Leone. Frequencies of fifth toe pedal symphalangism were calculated and compared among all three samples and found to be significantly higher in modern Japanese (83.7%) than in either Euro-Americans (46.4%) or African-Americans (44.0%). The Euro- and African-American frequencies were statistically indistinguishable for symphalangism of the fifth toe. In the fourth toe, however, the opposite result was found. The African-American frequency (7.9%) was significantly higher than the Euro-American frequency (2.6%), while no difference was found between the African-Americans and Japanese (11.7%). Since fourth toe pedal symphalangism has never been observed in the absence of fifth toe involvement, some of the same genes are clearly involved in producing the trait in both toes. However, differences in the pattern of fourth and fifth toe expression among the three groups identified in this study suggest that additional genetic or developmental factors may play a role in expression of pedal symphalangism in each of the toes.

Safety and utility of flecainide acetate in the routine care of patients with supraventricular tachyarrhythmias: results of a multicenter trial. The Flecainide Supraventricular Tachycardia Study Group.

Patients with supraventricular arrhythmias have been safely and effectively treated with flecainide. We conducted an open-label, 20-center trial to define further the safety and efficacy profile of oral flecainide in patients with supraventricular arrhythmias, including atrial tachycardias (ectopic or multifocal), atrial-ventricular tachycardias (reentrant), paroxysmal atrial fibrillation/flutter (PAF), and chronic atrial fibrillation (CAF). Our study population of 151 patients with documented supraventricular arrhythmias requiring treatment included 67 with paroxysmal supraventricular tachycardia (PSVT), 67 with PAF (symptoms < 15 days), and 17 with CAF (symptoms > of = 15 days)> The initial flecainide dose of 100 mg twice daily could be increased by 50 mg bid every 4 days to a maximum of 200 mg twice daily. Patients who were effectively treated could receive flecainide for 1 year. The study was terminated April 26, 1989, in response to interim results reported by the Cardiac Arrhythmia Suppression Trial (CAST). All patients were removed from the study by August 1989. At study termination 87% of PSVT, 73% of PAF, and 56% of CAF patients had improved symptomatically while on flecainide therapy. Eleven patients experienced cardiac adverse experiences: proarrhythmic events (3 patients), new or worsened congestive heart failure (7 patients), sinus pauses (1 patient). Cardiac side effects appeared to be more frequent in patients in the CAF group (5/17 patients), all of whom had structural heart disease. Overall, 45 (67%) PSVT, 43 (64%) PAF, and 9 (56%) CAF patients reported at least 1 noncardiac adverse experience; the most common were abnormal vision, dizziness, and headaches. One patient from the CAF group died; the death was considered to be unrelated to flecainide. Flecainide appears to be safe and effective treatment for patients with supraventricular arrhythmias of a variety of mechanisms and appears particularly effective for patients with PSVT. The efficacy is lowest and side effects most frequent in patients with CAF, as seen with other trials of antiarrhythmic medication in these patients. In the context of the CAST experience and other trials of antiarrhythmic drugs in patients with CAF, the balance of risk and benefit of therapy should be considered carefully before initiating treatment.

Heart transplant coronary artery disease detected by coronary angiography: a multiinstitutional study of preoperative donor and recipient risk factors. Cardiac Transplant Research Database.

BACKGROUND: Controversy exists regarding donor and recipient factors that promote the development and progression of coronary artery disease after heart transplantation and the likelihood of coronary artery disease causing death or retransplantation. METHODS: To investigate this issue in a large cohort of patients, we analyzed 5963 postoperative angiograms performed in 2609 of the 3837 patients undergoing heart transplantation at 39 institutions between January 1990 and December 1994. Coronary artery disease was classified as mild, moderate, or severe on the basis of left main involvement, primary vessel stenoses, and branch stenoses. Coronary artery disease was considered severe if left main stenosis was > 70% or 2 or more primary vessels stenoses were > 70% or branch stenoses were > 70% in all 3 systems. RESULTS: By the end of 5 years after heart transplantation, coronary artery disease was present in 42% of the patients, mild in 27%, moderate in 8%, and severe in 7%. Coronary artery disease-related events (death or retransplantation) had an actuarial incidence of 7% at 5 years and occurred in 2 of 3 of the patients with development of angiographically severe coronary artery disease. By multivariable logistic analysis, risk factors for donor coronary artery disease included older donor age (P < .0001) and donor hypertension (P=.0002). By multivariable analysis in the hazard function domain, risk factors identified for the earlier onset of allograft coronary artery disease included older donor age (P < .0001 ), donor male sex (P=.0006), donor hypertension (P=.07), recipient male sex (P=.02), and recipient black race (P=.01). The actuarial incidence of severe coronary artery disease was 9% at 5 years. CONCLUSIONS: Angiographic coronary artery disease is very common after heart transplantation, occurring in approximately 42% of the patients by 5 years. Older donor age, donor hypertension, and male donor or recipient predict earlier onset of angiographic allograft coronary artery disease. Although severe angiographic allograft coronary artery disease occurs in only 7% of the patients at 5 years, its presence is highly predictive of subsequent coronary artery disease-related events or retransplantation.

Evaluation of a waterless, scrubless chlorhexidine gluconate/ethanol surgical scrub for antimicrobial efficacy.

A new waterless surgical hand preparation containing 1% chlorhexidine gluconate (CHG) and 61% ethyl alcohol was evaluated for antimicrobial efficacy in comparison with a standard 4% CHG surgical scrub and a 61% ethyl alcohol control. Clinical studies were based on the Tentative Final Monograph for Health-Care Antiseptic Drug Products (TFM) (proposed rule) and the Standard Test Method for Evaluation of Surgical Hand Scrub Formulations (ASTM E1115-91). Two randomized, blinded, well-controlled clinical studies involving 137 healthy subjects were conducted to evaluate the antimicrobial effectiveness of the CHG/ethanol hand preparation in producing an immediate and persistent reduction in the normal bacterial flora of the hands. The CHG/ethanol hand preparation was applied without scrubbing or the use of water, and a standard 4% CHG reference product was applied with a scrub brush in 2 traditional 3-minute surgical scrubs. In 1 study, a 61% ethanol vehicle control treatment was applied without scrubbing or use of water. During a 5-day period, each study subject performed a series of 11 surgical scrubs with 1 of the test treatments. After the first treatment on days 1, 2, and 5, surgical gloves were worn for 3 or 6 hours. Bacterial samples were taken with the glove-juice technique at 1 minute, 3 hours, and 6 hours after treatment. The immediate bactericidal effect of the CHG/ethanol hand preparation after a single application resulted in a 2.5-log reduction in normal flora. This bactericidal effect persisted throughout the studies and eventually increased to a 3.6-log reduction after the 11th scrub on day 5. The log reductions of the CHG/ethanol hand preparation proved to be significantly better (P <.05) than that of the 4% CHG product at each sampling interval on days 1 and 2 and the sampling at 6 hours on day 5 and significantly better than the 61% ethanol vehicle at all times. The combination of 1% CHG and 61% ethanol had significantly greater microbial reduction than either the 4% CHG (without ethanol) or the 61% ethanol vehicle (without CHG).

Methods for evaluating changes in skin condition due to the effects of antimicrobial hand cleansers: two studies comparing a new waterless chlorhexidine gluconate/ethanol-emollient antiseptic preparation with a conventional water-applied product.

BACKGROUND: Hand-cleansing products that are milder to the skin of health care personnel are being developed, but the available methodologies to appropriately evaluate these products and quantify differences are not generally being applied in well-controlled studies. METHODS: Two randomized, blinded, bilateral comparison studies evaluated skin condition during use of 2 antiseptic hand preparation products: a new 1% chlorhexidine gluconate (CHG)/61% wt/wt ethanol antiseptic hand preparation in a unique emollient system for waterless/brushless application and a conventional 4% CHG antimicrobial product that is applied with water and a scrub brush. Trained technicians applied treatments 6 times (for a surgical scrub study) or 24 times (for a personnel handwash study) daily to the hands of healthy volunteers during 5 days of controlled washing. An expert grader evaluated skin for dryness, erythema, and roughness. Subjects completed a self-assessment questionnaire on skin condition. Transepidermal water loss was measured by an evaporimeter, and the skin surface hydration level was measured by an electrical conductance meter. RESULTS: Fifty-eight subjects were enrolled in the 2 studies and received both treatments. In general, skin treated with the waterless CHG/ethanol product scored significantly (P <.004) better on evaluations of visual dryness and erythema and showed greater improvement in the level of hydration (P <.003). In the health care personnel handwash study, transepidermal water loss was less than that for skin treated with the conventional CHG product (P <.002). Subject assessments showed similar results (total score, P <.007). CONCLUSIONS: All 3 approaches of expert grader evaluation, subject assessment, and instrumentation were in concordance, demonstrating that the waterless CHG/ethanol product was gentler to skin than the conventional CHG product.

Infants' fluoride intake from drinking water alone, and from water added to formula, beverages, and food.

In infants, the majority of total ingested fluoride is obtained from water, formula and beverages prepared with water, baby foods, and dietary fluoride supplements. Few studies have investigated the distribution of fluoride intake from these sources among young children at risk for dental fluorosis. The purpose of this study was to assess estimated water fluoride intake from different sources of water among a birth cohort studied longitudinally from birth until age 9 months. Parental reports were collected at 6 weeks, 3 months, 6 months, and 9 months of age for water, formula, beverage, and other dietary intake during the preceding week. Fluoride levels of home and child-care tap and bottled water sources were determined. This report estimates daily quantities of fluoride ingested only from water--both by itself and used to reconstitute formula, beverages, and food. Daily fluoride intake from water by itself ranged to 0.43 mg, with mean intakes < 0.05 mg. Water fluoride intake from reconstitution of concentrated infant formula ranged to 1.57 mg, with mean intakes by age from 0.18 to 0.31 mg. Fluoride intake from water added to juices and other beverages ranged to 0.67 mg, with means < 0.05 mg. Estimated total daily water fluoride intake ranged to 1.73 mg fluoride, with means from 0.29 to 0.38 mg.

Fluoride concentrations of infant foods.

Infants who ingest high amounts of fluoride can be at risk of dental fluorosis. The authors analyzed the fluoride concentration of 238 commercially available infant foods. Fluoride concentrations ranged from 0.01 to 8.38 micrograms of fluoride per gram, with the highest fluoride concentrations found in infant foods containing chicken. Infant foods, especially those containing chicken, should be considered when determining total fluoride intake.

Infants' fluoride ingestion from water, supplements and dentifrice.

Concerns about dental fluorosis and the paucity of detailed fluoride intake data prompted this longitudinal study of fluoride intake in infants from birth to 9 months of age. On average, water fluoride intake greatly exceeded that from dietary fluoride supplements or fluoride dentifrice. However, fluoride supplements and dentifrice contributed substantial proportions of fluoride intake among children using them. Some children had estimated fluoride intake from water, supplements and dentifrice that exceeded the recommended "optimal" intake (a level that has yet to be determined scientifically). Practitioners should estimate fluoride ingestion from all these sources if considering systemic fluoride supplementation.

Assessing fluoride levels of carbonated soft drinks.

BACKGROUND: Dental fluorosis occurs as a result of excessive total fluoride intake during tooth development. Some children may receive substantial intake from soft drinks, but few studies have reported fluoride levels in soft drinks. The authors examined the fluoride concentrations of 332 soft drinks. METHODS: Soft drinks were purchased from Iowa grocery stores. To identify production sites, the authors recorded product details and batch numbers. After decarbonating the drinks, the authors assayed samples for fluoride content using a fluoride ion-specific electrode, and reported the results in parts per million, or ppm, using appropriate standards and duplicate assessments. Descriptive statistics were used to summarize the findings. RESULTS: The fluoride levels of the products ranged from 0.02 to 1.28 ppm, with a mean level of 0.72 ppm. Fluoride levels exceeded 0.60 ppm for 71 percent of the products. Results varied substantially by production site, even within the same company and for the same product. There were no substantial differences between flavors or between diet and regular soft drinks. CONCLUSIONS: The majority of soft drinks had fluoride levels exceeding 0.60 ppm. Variation in fluoride levels probably is due largely to the different water sources used in production. CLINICAL IMPLICATIONS: With no fluoride levels marked on the soft drink products or easily available from the manufacturers, it is not possible for clinicians or consumers to directly estimate fluoride ingestion from carbonated beverages. Therefore, to reduce the risk of dental fluorosis, dental and medical practitioners should be cautious about prescribing dietary fluoride supplements to preschool-aged children in nonfluoridated areas who consume large quantities of carbonated soft drinks.

Assessing fluoride concentrations of juices and juice-flavored drinks.

Few studies have investigated fluoride exposures from juices and juice-flavored drinks manufactured with water. In this study, the authors analyzed 532 juices and juice drinks for fluoride. Fluoride ion concentrations ranged from 0.02 to 2.80 parts per million, in part because of variations in fluoride concentrations of water used in production. Children's ingestion of fluoride from juices and juice-flavored drinks can be substantial and a factor in the development of fluorosis.

Factors affecting dentifrice use and ingestion among a sample of U.S. preschoolers.

PURPOSE: This study was performed to assess the actual amount of dentifrice used and ingested and factors associated with use/ingestion among 28 U.S. preschoolers aged 40 to 48 months. METHODS: Using their regular dentifrice brands/flavors and small child-sized toothbrushes (Oral -B 5), the participants or their parents placed dentifrice on toothbrushes three times to assess the quantity used and its consistency. Their brushing behaviors were observed and the amounts of dentifrice ingested were indirectly measured. Afterward, the parents and children placed a "pea-sized" amount of dentifrice on their toothbrushes. RESULTS: The participants were generally consistent in quantity applied, averaging 0.256 g (range 0.035 g-0.620 g; standard deviation 0.177 g) of dentifrice per brushing. Children, either alone or with parental assistance, placed more dentifrice than either mother or father alone (P = 0.007). The estimated mean ingested fluoride was 0.17 mg F per brushing, an average of 62% of the amount of dentifrice used (range up to 98%). Amount of ingested fluoride was positively associated (P < 0.05) with the amount of dentifrice used, and negatively associated with parental assistance in brushing. When asked to apply a pea-sized quantity, the mean quantity applied was 0.314 g (range 0.064 g-0.521 g). CONCLUSIONS: This study further supports the use of small amounts of dentifrice in young children, because they ingest substantial proportions of dentifrice.

Water and formula fluoride concentrations: significance for infants fed formula.

The independent contributions of formula and water to the total fluoride (F) intake from the diet of formula-fed infants is not fully documented. Although the precise timing and mechanism by which dental fluorosis occurs has not been fully defined, water F levels can be an important consideration in the risk of dental fluorosis for formula-fed infants. An assessment of 1,308 participants younger than 2 years old revealed that: 81% of homes received public water; 19% received well water; 26% of participants used bottled water; and 11% used some kind of filtration system. In this study, virtually all formulas consumed by the birth cohort and water sources used in the reconstitution of these formulas were assayed for F using a F ion specific electrode and direct read method, except for soy-based formulas, which were analyzed by microdiffusion (modified Taves). Among 78 commercially available bottled waters in Iowa, F levels ranged from 0.02 to 1.36 ppm (mean 0.18 ppm), 83% from 0.02 to 0.16 ppm, 7% from 0.34 to 0.56 ppm, 1% had a F level of 0.88, and 9% had F levels > 1.0 ppm. Among 47 casein (milk)-based formulas, 16 ready-to-feed (RTF) formulas had levels of 0.04-0.55 ppm F (mean 0.17 ppm), 14 liquid concentrates (LC) reconstituted with distilled water had levels of 0.04-0.19 ppm F (mean 0.12 ppm), and 17 powdered concentrates (PC) reconstituted with distilled water had levels of 0.05-0.28 ppm F (mean 0.14 ppm). The 17 soy-based formulas had a range of 0.04-0.47 ppm F (mean 0.26 ppm).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of different regimens for surgical hand preparation.

Twenty surgical staff members participated in a clinical trial to compare the microbiology and skin condition of hands when using a traditional surgical scrub (TSS) with a detergent-based antiseptic containing 4% chlorhexidine gluconate (CHG) and a short application without scrub of a waterless hand preparation (HP) containing 61% ethyl alcohol, 1% CHG, and emollients. The HP was associated with less skin damage (P = .002) and lower microbial counts postscrub at days five (P = .002) and 19 (P = .02). The HP protocol had shorter contact time (HP mean [M] = 80.7 seconds; TSS M = 144.9 seconds; P < .0001), and more subjects preferred the HP regimen (P = .001). The HP performed better than the TSS, was less costly, and should be evaluated in larger trials and considered for widespread implementation.

A uniform with uniformity.

Clothing is a powerful form of non-verbal communication, conveying socio-economic status, occupational role and even the authority and power vested in that role. The traditional hospital nursing uniform reflects its historic military and religious foundations, and, many would say, the servile rank of the wearer.

Natural root caries: a histologic and microradiographic evaluation.

The purpose of this study was to obtain information about the detailed histopathology of naturally occurring root caries. Fifty extracted human teeth exhibiting some degree of root caries were sectioned longitudinally and examined with transmitted light, polarized light and microradiography. The occurrence of the histological zones of dentinal caries was tabulated and revealed a lesion body in all cases. Light microscopy showed the same basic features as microradiography and was most useful when the sections were imbibed in quinoline. A structureless area below the main body of the lesion was observed in 77% of the cases when using quinoline. This fluid more clearly defined the extent of the lesion and may show a "phenolic reaction" when using polarized light microscopy. Partial radiopaque surface layers were observed in almost 80% of the sections. This study has described the detailed histopathology of root caries, and aids in the development of model systems to evaluate this emerging dental health problem.