Biomedical subjects

J Takagi

Publications and source records attributed to J Takagi.

112 records · Page 7Linked to original sources

PubMedDate not supplied

Noninvasive evaluation of systolic pressures of pulmonary artery and right ventricle using contrast-enhanced doppler echocardiography: comparative study using sonicated albumin or glucose solution.

Evaluation of pulmonary arterial pressure is essential for the diagnosis and management of patients with congenital heart disease; it is usually done by cardiac catheterization. An alternative, noninvasive method may be clinically more useful. The purpose of this study was to assess the usefulness of the noninvasive determination of systolic pressure of the pulmonary artery and right ventricle by contrast-enhanced Doppler echocardiography. We selected 30 pediatric patients (28 with trivial or nonsignificant tricuspid regurgitant Doppler signals and 2 with significant tricuspid regurgitant Doppler signals) aged 2 months to 21 years. The flow velocity of tricuspid regurgitation was measured with continuous-wave Doppler of the right ventricular inflow view or left parasternal or apical four-chamber view before and after injection of two types of contrast medium (hand-agitated 5% glucose or sonicated albumin). The systolic pressure of the pulmonary artery was assessed as the estimated right ventricular systolic pressure (albumin method) minus the peak pressure gradient across the pulmonary valve (nonenhanced Doppler method). After injection of hand-agitated 5% glucose and sonicated albumin, trivial tricuspid regurgitation signals were enhanced in 25 of 28 patients (89%). In two patients, spectral envelopes were well defined enough to obtain the peak systolic velocity of the tricuspid regurgitation jet without contrast medium injection. Peak velocity was not altered by injection of contrast medium in these patients. There was significant correlation between the estimation by contrast-enhanced Doppler using hand-agitated 5% glucose and the cardiac catheterization measurement of the transtricuspid pressure gradient (r = 0.88). The transtricuspid pressure gradients obtained by continuous-wave Doppler during sonicated albumin enhancement corresponded closely to those measured by cardiac catheterization (r = 0.95). Pulmonary arterial and right ventricular systolic pressures measured by Doppler using sonicated albumin and those obtained by cardiac catheterization were highly correlated (right ventricle, r = 0.96; pulmonary artery, r = 0.95). In conclusion, this technique may be a valuable noninvasive method for determining accurate right ventricular and pulmonary arterial systolic pressures.

Adolescent↗

PubMedDate not supplied

Carotid artery approach to balloon aortic valvuloplasty in infants with critical aortic valve stenosis.

We compare the clinical efficacy of two approaches for balloon aortic valvuloplasty (BAV) in infants with critical aortic valve stenosis. The approaches were through the carotid artery and the femoral artery. Eight catheterizations for BAV were performed in seven consecutive patients with critical aortic stenosis: four BAVs were approached through the femoral artery and four through the right common carotid artery. We inserted a 5F sheath into the right common carotid artery by a cutdown procedure; after BAV the sheath was removed and the carotid arteriotomy sutured with 7-0 monofilament. Two cases in which the femoral artery approach was used resulted in failure to perform BAV; two cases had complications. All four cases with the carotid artery approach were successful, with no complications; aortography performed 3 months after one balloon valvuloplasty revealed a smooth, unobstructed right carotid artery. Use of the carotid artery approach may reduce serious complications with BAV and offers quicker, easier maneuvering in infants and neonates with critical aortic valve stenosis.

Aortic Valve Stenosis↗

PubMedDate not supplied

Chemical compatibility of cefmetazole sodium with ranitidine hydrochloride during simulated Y-site administration.

The stability of cefmetazole sodium and ranitidine hydrochloride was studied under conditions simulating administration via a Y-injection site into a primary infusion line. Cefmetazole sodium was reconstituted with both 0.9% sodium chloride injection (50 mL or 100 mL) and 5% dextrose injection (50 mL) to produce premixing concentrations of cefmetazole 10 and 20 mg/mL. Ranitidine hydrochloride injection was diluted with 50 mL 0.9% sodium chloride injection to give premixing concentrations of ranitidine 1 mg/mL. To simulate Y-site administration, 2 mL of cefmetazole was mixed with 2 mL of ranitidine in a 10-mL glass test tube. All study mixtures were prepared in triplicate and stored at room temperature (22-23 degrees C) under normal fluorescent room lighting. Samples of these admixtures were inspected for visual changes and tested for pH. The concentrations of two drugs were immediately determined by stability-indicating high-performance liquid chromatographic assay methods after mixing and at 1, 2, and 4 hours. No visual changes were observed. The pH in the admixtures was influenced by concentrations of the two drugs. The pH of each single-drug solution did not change during the study period. On the other hand, the pH of any admixtures of cefmetazole and ranitidine solutions prepared with 0.9% sodium chloride or 5% dextrose injection, decreased. Cefmetazole in any of the admixtures with ranitidine retained greater than 95% of its original concentration for 4 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Cefmetazole↗

PubMedDate not supplied

Development of a novel polyimide hollow fiber for an intravascular oxygenator.

The authors have synthesized a novel fluorinated polyimide to develop a membrane material for oxygenators and fabricated polyimide hollow fibers for use in an intravascular oxygenator. A dry/wet phase inversion process has been applied to a spinning process to prepare an asymmetric polyimide hollow fiber. The outer surface of the hollow fiber consists of an ultrathin, dense skin layer, with a calculated apparent thickness of approximately 60 nm. The fiber diameter was 800 microns with a wall thickness of 130 microns. The asymmetric hollow fiber has two advantages because (a) the hollow fiber does not produce plasma leakage due to the dense skin layer of the surface and (b) O2 and CO2 transfer rates through the hollow fiber are enhanced due to the ultrathin skin layer and are significantly larger than those of presently available membrane oxygenators. The blood compatibility of the polyimide hollow fiber without heparinization has been evaluated in vitro. Deformation and aggregation of platelets adherent to the fibers were not observed, and the polyimide suppressed platelet activation. The polyimide significantly reduced the production of anaphylatoxin and also suppressed complement activation.

Carbon Dioxide↗