Biomedical subjects

F Clubb

Publications and source records attributed to F Clubb.

3 recordsLinked to original sources

PubMed1998

Percutaneous Application of Fibrin Sealant to Achieve Hemostasis Following Arterial Catheterization.

OBJECTIVES: The present study sought to investigate the safety and efficacy of a new fibrin sealant using percutaneous delivery techniques. BACKGROUND: The femoral approach has become the preferred means of access for percutaneous diagnostic and interventional procedures. Control of access site bleeding following catheterization, however, remains a significant problem in interventional cardiology. METHODS: Adult mongrel dogs were used in this study. Series 1 compared the effectiveness of fibrin sealant vs. manual compression alone in the presence of anticoagulants, thrombolytic, and antiplatelet agents. Series 2 assessed fibrin sealant safety. Series 3 examined fibrin sealant performance under elevated blood pressure levels. RESULTS: Series 1: Hemostasis was achieved in all fibrin sealant sites in significantly less time (8.5 +/- 4.3 min) with no major complications compared to manual compression sites (65.2 +/- 19.3 min) accompanied by serious complications. For all adjunctive agents employed, hemostasis was achieved in fibrin sealant sites in significantly less time (warfarin 9.9 +/-.2, urokinase 11.2 +/- 5.6, ReoProª 10.5 +/- 6.3 min) than for manual compression sites (warfarin 86.5 +/- 21.4, urokinase 89.8 +/- 36.3, ReoPro 77.9 +/- 26.5 min). Series 2: I25 iodine-labeled fibrinogen sealant was applied to puncture sites with no traces of circulating radioactivity observed over a one-hour period. Series 3: hemostasis was achieved under elevated blood pressure conditions in all animals. Histologic studies showed complete re-absorption of fibrin sealant 28 days post-procedure with no evidence of foreign body reaction. CONCLUSIONS: Percutaneous application of fibrin sealant to achieve hemostasis following catheterization appears to be a simple, safe, and highly effective procedure in a canine model.

Journal Article↗

PubMed1986

Chronic antithrombogenic biomaterials screen.

The widespread usage of chronic implantable sensors in cardiac device systems has been hampered by both sensor technology issues and the lack of surface passivations with chronic antithrombogenic capabilities. In this study, dummy pacing leads with six types of passivations were implanted for 17 weeks in 36 dogs to assess thrombogenic character, degree of tissue growth and encapulation, and general performance in providing optically clear windows into the blood or body tissues. Asceptic surgical procedures were used and complete blood work-up was performed every two weeks postop. Two dogs served as surgical shams to monitor system artifacts. At explant the devices fairly clearly divided themselves into two groups based on the percent of exposed surface area covered by gross macroscopic tissue accumulations. There were three passivated types in each group. Scanning electron microscopy (SEM) and energy dispersive analysis of x-rays (EDAX) techniques were used to investigate further the samples from the three passivation types that performed "better" based on percent surface area analysis. Issues that became prominent were substrate surface finish and topography, and some mineralization phenomena. Some of the evidence raises the possibility that processes that provide chronic antithrombogenic performance might also enhance mineralization or propensity toward natural breakdown processes. These questions are now being more closely addressed in follow-up studies now in progress.

Animals↗

PubMedDate not supplied

A bovine model for detecting high intensity transient signals originating from mechanical heart valves.

In patients with mechanical heart valves (MHVs), transcranial Doppler methods commonly detect high intensity transient signals (HITS) representing microemboli. These microemboli, which are presumably gaseous, may cause stroke and cognitive deterioration. A bovine model was therefore developed for studying the relationship between mitral MHV induced HITS and potential etiogenic factors. We placed an 18 mm, 4 MHz Doppler probe in the brachiocephalic artery to detect MHV induced microbubbles at baseline (rest) and under 9 other conditions. To elucidate the gas composition (CO2 or N2) of the microbubbles, we administered 1%, 3%, and 5% CO2, and 100% O2. To determine effect of the heart rate, we paced the heart at 120, 160, and 180 bpm. To alter the myocardial contractility, we gave dobutamine and esmolol. Two independent, blinded observers counted the HITS from recorded doppler spectra. HITS were defined by an initial unidirectional spectral deviation, a signal power of >8 dB relative to the background power, and lack of a cyclic appearance. The electrocardiogram, aortic and LV pressures, and LV dP/dt were obtained telemetrically. The calves were studied 4 to 6, 8 to 10, and 12 to 14 weeks postoperatively, after which the animals were sacrificed at an approximate 4 month study duration, and a postmortem evaluation of the heart and the main viscera was performed. In all, 27 HITS recordings were made in 10 calves. Myocardial contractility was the only factor to significantly affect HITS frequency; the heart rate and blood gas concentrations had minimal effect on HITS frequency. Our bovine model will be useful for assessing valve designs, as well as the mechanism of HITS, the composition of the microemboli, and their possible pathophysiologic effects on the kidneys and brain.

Adrenal Glands↗