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Biomedical subjects

T Tanimoto

Publications and source records attributed to T Tanimoto.

At least 289 records · Page 16Linked to original sources
PubMed1982

[Myocardial imaging in patients with Kawasaki disease: exercise stress imaging and serial studies].

Thallium-201 myocardial imaging was performed in 80 children with coronary arterial lesions due to Kawasaki disease in order to assess the value of serial and exercise myocardial imagings. In eight of these children, abnormalities of the image were noted. Twenty children had serial thallium studies with an interval of three to 18 months, and five of these showed changes in the image including appearance of a new perfusion defect in one patient and improvement of perfusion defects in four. These changes of the myocardial image were correlated well with coronary angiographic findings obtained within a few days of the isotope studies. It was noted that the changes of the myocardial image were more frequently observed at relatively recent period recovered from Kawasaki disease. Exercise myocardial imaging using a bicycle ergometer was performed in eight children with coronary arterial lesions. In three an evidence of improvement of the myocardial perfusion was noted immediately after exercise as well as on the delayed image. In one patient, a decrease of the perfusion in the apex and inferior wall was noted immediately after exercise. On the observed image, image of the apex improved but that of the inferior wall remained hypoperfused. Thus thallium-201 myocardial imaging was considered to permit the best noninvasive documentation of ongoing myocardial perfusion abnormalities in patients with Kawasaki disease. Exercise myocardial imaging was found to be useful in differentiating the viable from nonviable myocardium. It was to be emphasized that quantitative evaluation by computer-assisted analysis was particularly valuable in detecting small areas and in a comparison of the myocardial images.

Adolescent↗
PubMed1982

[Myocardial imaging in patients with transposition of the great arteries: comparison between Mustard and Rastelli operations].

Thallium-201 myocardial imaging was performed in 21 patients with transposition of the great arteries (TGA). Thirteen patients were studied before operation, eight patients after Mustard operation and five patients after Rastelli operation. Five patients were studied sequentially before and after the surgery. Each image was compared with hemodynamic and angiographic findings in order to assess the usefulness of this method. In the 13 patients with preoperative TGA, it was possible to differentiate TGA with the intact ventricular septum from TGA with associated anomalies such as patent ductus arteriosus or ventricular septal defect, and also TGA with pulmonary hypertension or pulmonary stenosis from TGA without them by evaluating the degree of thallium uptake in the free wall of the pulmonary ventricle (anatomical left ventricle). The degree of thallium uptake was well correlated with systolic pressure of the pulmonary ventricle (r = 0.98). In the 13 patients with postoperative TGA, it was less correlated with the pulmonary ventricular systolic pressure (r = 0.83). Four cases sequentially studied showed a marked decrease in thallium uptake in the pulmonary ventricle 10 to 16 months after Rastelli operation. But the corrected thallium uptake (thallium activity/ventricular systolic pressure) was more increased compared with the uptake of the systemic ventricle after the surgery. This was probably related to a decrease of the pressure load to the pulmonary ventricle following the surgery and to the fact that there should be some delay of a decrease of the ventricular mass. An increased lung uptake of thallium was noted in the cases of tricuspid regurgitation after Mustard operation, but the degree of regurgitation was not clearly correlated with the increase of thallium uptake in the lung. In five cases after Rastelli operation, one patient showed a high degree of thallium uptake of the pulmonary ventricle (anatomical right ventricle), and the conduit valve calcification and severe pulmonary stenosis were confirmed by cardiac catheterization and angiography. Thus myocardial imaging provides a reliable mean for the qualitative and quantitative assessment of TGA before and after operation.

Child, Preschool↗
PubMed1981

Trapidil stimulation of slow Ca2+ current in cardiac muscle.

The effect of trapidil, a coronary vasodilator and positive inotropic agent (associated with elevated tissue cyclic AMP levels due to phosphodiesterase inhibition), was examined on the electrophysiological properties of cardiac muscle. Specifically, the trapidil was tested for its ability to induce slow action potentials (APs), and to affect the maximum upstroke velocity (+Vmax) of the slow APs in the ventricular myocardial cells of isolated perfused chick hearts. The effect of trapidil on the contractions accompanying the slow APs and on the tissue cyclic AMP levels was also examined. To study the slow channels exclusively, the fast Na+ channels were voltage-inactivated by elevated (25 mM) K+. In this condition of functional removal of the fast channels, the hearts could not be excited even by intense electrical stimulation. It was found that trapidil (10(-4)--10(-3) M) induced slow APs accompanied by contractions. Elevation of the trapidil concentration produced dose-dependent increases in +Vmax, dT/dt (first derivative of developed tension) and cyclic AMP. These effects of trapidil were not affected by propranolol, suggesting that they were not mediated by beta-adrenergic receptors. These results support the hypothesis that intracellular cyclic AMP levels regulate the number of available slow channels, thereby controlling contractile force in the heart muscle via the Ca2+ influx mediated by slow channels.

Action Potentials↗
PubMed1981

An autopsied case of an elementary school boy with sudden death four years after Kawasaki disease: on the problem of present method of cardiac mass screening of school children.

An 8 year-old boy died suddenly 4 years after the onset of Kawasaki disease. He was examined by a cardiac mass screening for school children one and a half year before the death, and was evaluated as having no sequela of Kawasaki disease. The autopsy showed coronary arterial aneurysms and obstruction with fresh and old myocardial infarction. One of the problems of the present method for cardiac mass screening for school children is that it is performed only with history taking, physical findings and electrocardiograms. This method is completely insufficient to find out coronary involvement as a sequela of Kawasaki disease. All the children with history of Kawasaki disease should be examined by two dimensional echocardiography, which is the most sensitive and specific noninvasive method to detect the coronary involvement in our experience.

Autopsy↗