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Biomedical subjects

T Isshiki

Publications and source records attributed to T Isshiki.

At least 91 records · Page 5Linked to original sources
PubMed1990

Postoperative angiographic evaluation of gastroepiploic artery grafts: technical considerations and short-term patency.

Follow-up angiography was performed in 37 patients with right gastroepiploic artery (GEA) grafts at 27 +/- 32 days postoperatively. By the femoral approach, a 5F cobra or twist catheter was advanced selectively into the gastroduodenal artery (GDA) over a plastic-coated guidewire. In 29 patients, the GDA was successfully catheterized, and the GEA grafts were clearly visualized by the injection of 3-7 ml of contrast medium. GDA catheterization was unsuccessful in 8 patients, but in 4 of them the grafts were well visualized when 15-20 ml of contrast was injected. In the other 4 patients, visualization of the GEA grafts was poor, but the distal portions were outlined by retrograde perfusion from the native right coronary arteries. A total of 34 GEA grafts were patent (92%), and the diameters of these grafts were adequate when compared with respective recipient coronary arteries (2.8 +/- 0.9 and 2.3 +/- 0.6 mm, respectively; P less than .05). No complications were noted except for transient vasospasm (3 patients) in the GEA, hepatic artery, or both, which was relieved by the intra-arterial injection of isosorbide dinitrate (2.5 mg). Thus, the over-the-wire technique allows simple and safe GDA catheterization, which is essential for obtaining good visualization of GEA grafts.

Adult↗
PubMed1990

Angioplasty of stenoses adjacent to aneurysmal coronary artery disease.

We examined the effectiveness and safety of performing angioplasty on stenoses adjacent to aneurysmal coronary artery disease. Out of 386 consecutive lesions (270 patients) on which we performed angioplasty, 13 lesions (13 patients) were within one balloon length of aneurysmal disease (group A) and 373 lesions (257 patients) were not (group NA). Angioplasty had previously been performed on 10 lesions (77%) in group A but only on 112 lesions (30%) in group NA (p less than 0.01). In group A the angioplasty success rate was 100% (13/13). The maximum inflation pressure was 6.5 +/- 1.1 atm, the frequency of inflation was 6.1 +/- 2.8, the average inflation duration was 60 +/- 0 sec, and the balloon/artery ratio was 1.20 +/- 0.11. There were no major complications. Restenosis occurred in only one lesion. There were no significant differences in the angioplasty results, procedures, complications and the incidence of restenosis between both groups. The ratio of the diameter of the aneurysmal disease to the mean diameter of the normal adjacent segments remained unchanged throughout the follow-up period. These data suggest that angioplasty may be an effective and safe treatment for those stenoses that are adjacent to aneurysmal coronary artery disease.

Angioplasty, Balloon, Coronary↗
PubMed1989

High-resolution transmission electron microscopy of inorganic materials in cellular and topological random systems.

The structure of amorphous Se films, in the topological random system, has been studied by the computer-simulation, electron diffraction (ED), and high-resolution transmission electron microscopy (HRTEM). As an example of HRTEM of the cellular random system, our recent investigation on Ba-ferrites is reviewed beforehand. In HRTEM images of spin-glass BaTi2-xSnxFe4O11 (x less than 0.6), magnetic clusters or clusters of FeO6-octahedra surrounded by TiO6-octahedra have been found. The structure of BaSn2Fe4O11 (x = 2) has been determined. The ordering of Sn (Ti) and Fe ions increases with increasing x, which interprets the change from the spin-glass state to nonspin-glass state at x = 0.6. It is shown that a cluster of polarized lattice ions is detectable in images of polar-glass BaxK2-xFexTi6-xO13 (x greater than or equal to 1.2). The structure models of amorphous Se films forming on a substrate have been constructed on a computer, and their radial distribution function (RDF) and HRTEM images have been calculated. Experimental RDF and HRTEM images have been obtained from vacuum-deposited amorphous Se films and are compared with the calculated ones. It is concluded that in the as-deposited films most of Se molecules may be composed of Se atoms as small as three and that by the electron-beam irradiation the molecules link to form spiral chains in amorphous state and then arrange to have the hexagonal crystal structure.

Chemical Phenomena↗
PubMed1988

Hemodynamic comparison of diltiazem and TA-3090 in spontaneously hypertensive and normal Wistar-Kyoto rats.

Systemic and regional hemodynamic effects of 2 benzothiazepine derivatives, diltiazem and its congener TA-3090, were studied both acutely and chronically in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. All hemodynamic data were obtained in the conscious state using the reference sample radiomicrosphere method. Mean arterial pressure was reduced significantly with both immediate and more long-term treatment with both drugs in the SHR. The hypotensive action of TA-3090 was about 3 times as potent as diltiazem. The pressure reduction with both drugs was associated with a decrease in total peripheral resistance. TA-3090 seemed to have lesser effect on heart rate than diltiazem, although its net effect on cardiac output was similar, remaining unchanged in each study group. After intravenous injection, both diltiazem and TA-3090 significantly reduced vascular resistances of the major target organs of hypertension: heart, brain and kidneys in SHR. However, with prolonged treatment, organ vascular resistances seemed to be nonuniformly distributed. Intrarenal hemodynamics revealed significant differences between SHR and WKY rats after intravenous diltiazem and prolonged treatment with TA-3090. Thus, efferent as well as afferent arteriolar resistance decreased and therefore calculated glomerular capillary hydrostatic pressure decreased in SHR; however, efferent resistance and glomerular pressure remained unchanged in WKY rats. In contrast, intravenous TA-3090 evoked no such differences. Thus, diltiazem as well as TA-3090 dilated efferent as well as afferent arterioles in the SHR but not in the WKY rats. This effect was associated with a reduction in glomerular capillary pressure, preventing glomerular hyperfiltration through efferent arteriolar dilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Immediate and prolonged hemodynamic effects of TA-3090 on spontaneously hypertensive (SHR) and normal Wistar-Kyoto (WKY) rats.

Systemic and regional hemodynamic effects of the new effects of the new calcium antagonist TA-3090, a benzothiazepine derivative that is similar to diltiazem, were studied both acutely (0.3 and 0.6 mg/kg IV) and chronically (30 mg/kg by once-daily gastric gavage for 3 weeks) in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. All hemodynamic data were obtained in the conscious state using the reference sample radiomicrospheres method. Mean arterial pressure was reduced significantly by both immediate and long-term treatment in both rat strains. Stroke index remained unchanged in each study group, but the heart rate of the SHR and WKY decreased and increased, respectively, with the higher dose in the intravenous aspect of this study. As a result, total peripheral resistance decreased significantly in all groups, normotensive or hypertensive, although this fall was not distributed uniformly throughout the body. Intrarenal hemodynamics revealed significant differences between SHR and WKY by prolonged treatment with TA-3090. Efferent as well as afferent glomerular arteriolar resistances decreased and therefore calculated glomerular capillary hydrostatic pressure decreased in SHR; however, efferent glomerular arteriolar resistance and glomerular pressure remained unchanged in WKY. By contrast, in the acute study, no such differences were obtained. Further, 3 weeks' treatment did not alter cardiac mass in either rat strain. Thus, TA-3090 decreased arterial pressure through a fall in total peripheral resistance without major cardiac effects in both rats strains. In contrast, the agent reduced vascular resistances only in the SHR; and this was achieved with dilation of both the afferent and efferent glomerular arterioles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Comparison of functional responses of canine coronary artery and saphenous vein.

Functional responses of canine circumflex coronary arteries and saphenous veins before and after grafting surgery were assessed following physiologic and pharmacologic interventions. Developed tension of ringed segments of vessels was recorded isometrically. Dose-dependent responses to norepinephrine revealed significantly greater responses of saphenous veins than coronary arteries (maximal responses were 2.79 +/- 0.45 and 0.44 +/- 0.34 g, respectively; p less than 0.001). Sensitivity to norepinephrine [as evaluated by 50% effective dose (ED50) value] was 3.3 times greater in the saphenous veins (p less than 0.001). STA2, a synthetic thromboxane A2 analog (see Methods), produced similar contractions of both vessels [maximal responses were 2.13 +/- 0.37 g in saphenous vein and 1.64 +/- 0.85 g in coronary artery; p less than not significant (NS)], while sensitivity to STA2 of saphenous veins was 3.1 times greater than that of coronary arteries (p less than 0.001). In contrast to the foregoing responses, coronary arteries demonstrated significantly greater responses to potassium than saphenous veins (maximal responses were 2.16 +/- 0.71 g and 1.40 +/- 0.56 g, respectively; p less than 0.001). Moreover, coronary arteries revealed 1.6 times greater sensitivity than saphenous veins (p less than 0.001). When saphenous veins were transplanted into the femoral artery, the segments of the grafts (2 weeks or 3 months after surgery) revealed 4.0 and 1.7 times greater sensitivity (denervation supersensitivity) to norepinephrine and potassium than those of the control veins (p less than 0.01, respectively). Contractile tension response, however, decreased by at least 50% 3 months after surgery, most probably due to a thickened vessel wall and a reduced compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Diltiazem maintains renal vasodilation without hyperfiltration in hypertension: studies in essential hypertension man and the spontaneously hypertensive rat.

The systemic and renal hemodynamic effects of diltiazem were determined in patients with mild to moderately severe essential hypertension and in rats with spontaneous hypertension (SHR). Seven patients were treated for one full year (300 mg/day, average dose) and 10 SHR and 10 normotensive Wistar-Kyoto (WKY) rats received 1 and 2 mg/kg, intravenously. In both man and rat with genetic hypertension, arterial pressure was reduced through a fall in total peripheral resistance without associated reflexive increases in heart rate and cardiac index; and the patients demonstrated no change in plasma volume. In both man and the SHR: renal blood flow increased (in SHR not statistically significant) as arterial pressure and renal vascular resistance fell; glomerular filtration rate (GFR) remained unchanged and the filtration fraction (FF) significantly fell; and calculated intrarenal hemodynamic indices (using the Gomez formulae) demonstrated falls in afferent and efferent glomerular arteriolar pressures and resistances and in intraglomerular pressures, thereby explaining the unchanged GFRs and the decline in FF. These findings in both hypertensive man and rat are in contrast with those of the normotensive WKY that only demonstrated a fall in afferent glomerular arteriolar resistance. Thus, these data demonstrate that diltiazem controlled arterial pressure in both forms of genetic hypertension associated with falls in systemic and renal arteriolar resistances and with improved intrarenal hemodynamics without glomerular hyperfiltration.

Adult↗
PubMed1986

Periodic fluctuation of blood pressure in a case of norepinephrine secreting extra-adrenal pheochromocytoma.

A rare case of pheochromocytoma with wide fluctuation of blood pressure at regular 7-min intervals is described. Direct blood pressure monitoring revealed periodic changes between 120/80 mmHg and 220/130 mmHg. The plasma norepinephrine concentration increased selectively in parallel with the elevation of the blood pressure. The tumor was found adjacent to the left kidney, and all abnormal data improved after its resection.

Adrenal Gland Neoplasms↗
PubMed1985

Immobile right aortic leaflet in a case of the aortitis syndrome complicated by a left coronary sinus aneurysm.

A 37-year-old housewife had the aortitis syndrome complicated by acute aortic regurgitation and severe coronary insufficiency. Her echocardiogram at the level of the aortic valve ring revealed an enlarged left aortic sinus and an oscillating membranous structure centrally in the lumen of the aorta. At emergency surgery, there was no intimal flap in the ascending aorta, but there was a 4 cm diameter aneurysm of the left aortic sinus. The leaflets of the aortic valve per se were normal. Following its surgical repair and an aortic valve replacement, prednisolone was administered, and all abnormal laboratory data were corrected. The oscillating structure in the ascending aorta was considered to be the right aortic leaflet whose reduced mobility was caused by a distorted aortic valve ring due to the aneurysm. An immobile aortic leaflet is an extremely rare echocardiographic finding worthy to be reported.

Adult↗
PubMed1984

Intravenous leiomyomatosis of the uterus with continuous extension into the pulmonary artery.

A 56-year-old woman presented with an intracardiac tumor, as shown by two-dimensional echocardiography. Surgical treatment, undertaken in two stages, revealed a tumor which arose in the uterus, passed through both ovarian veins, the inferior vena cava, the right atrium and ventricle, and the pulmonary trunk, and extended to both pulmonary arteries. The upper portion of the tumor was removed in the first surgical operation, and the remaining tumor was removed during a second operation 1 year later. Both specimens were identical in appearance, and a pathohistological diagnosis of benign leiomyoma was made.

Echocardiography↗
PubMed1982

[Effects of beta-blockers and Ca antagonists on diastolic function of the hypertrophied left ventricle: an echocardiographic study].

Left ventricular (LV) relaxation was studied in patients with hypertensive heart disease with LV hypertrophy (HHD, n = 25) and hypertrophic cardiomyopathy (HCM, n = 9), and these data were compared with that of normal controls (n = 20). The effects of oral administration of propranolol (n = 11), pindolol (n = 3), nifedipine (n = 6) and diltiazem (n = 5) in patients with HHD and that of propranolol (n = 9) in patients with HCM were also studied. Isovolumic relaxation time (IRT) was measured using dual M-mode echocardiography and peak normalized rate of change of the LV cavity in early diastole (peak dD/dt/D) was calculated by M-mode echocardiography using a digitizer and microcomputer system. IRT was significantly longer in HHD (112 +/- 24 msec, p less than 0.001) and in HCM (85 +/- 40 msec, p less than 0.05) compared with that of normal subjects (64 +/- 24 msec). The normal value of peak dD/dt/D was 3.8 +/- 0.7 sec-1, and it was significantly lower in HHD (2.7 +/- 0.8 sec-1, p less than 0.001). It was also lower in HCM (3.2 +/- 0.8 sec-1), but without a statistical significance. In HHD there was a significant relationship (r = -0.611, p less than 0.01) between peak dD/dt/D and wall thickness of the LV (interventricular septum + LV posterior wall). There was no significant change in IRT before and after the administration of beta-blockers and calcium antagonists except nifedipine in HHD (before: 116 +/- 28 msec, after: 80 +/- 14 msec, p less than 0.005). It was probably due to the effect of an accompanied decrease in heart rate. However, peak dD/dt/D was significantly increased in both HHD and HCM groups after the administration of propranolol, pindolol, nifedipine and diltiazem. These data show that LV relaxation is abnormal in the hypertrophied LV. Although the genesis of this abnormality is not clear, there seems to be a close relationship between the relaxation abnormality and increased LV mass in HHD. Oral administration of propranolol, pindolol and diltiazem for patients with HHD and propranolol for patients with HCM seems to improve the abnormal LV relaxation of each disease.

Adrenergic beta-Antagonists↗
PubMed1981

[Two-dimensional echocardiographic observation of ruptured chordae tendineae of the mitral valve: Its localization and uneven development of papillary muscles (author's transl)].

Twenty-three cases with ruptured chordae tendineae (RCT) of the mitral valve and 9 normal control cases were studied by two-dimensional echocardiography. Mitral valve replacement (MVR) was performed in 13 of the 23 cases. The preoperative diagnosis of RCT was proven accurately at operation in all except 2 cases with bacterial endocarditis. Whether RCT occurred in the antero-lateral or in the postero-medial commissural side could be determined perfectly. RCT was observed in the postero-medial side more often than in the anterolateral side, i.e., postero-medial side in 16 (9 operated) and antero-lateral side in 5 (2 operated). This tendency has also been noted in other Japanese reports regardless of the cause of RCT. In the short axis view at the level of the papillary muscles, the area of the posterior papillary muscles was smaller than the area of the anterior papillary muscles in the RCT cases. It is speculated that the smaller size of the posterior papillary muscles has a certain relation with the more frequent RCT in the postero-medial commissural side.

Adolescent↗
PubMed1980

Cross-sectional echocardiographic observation of the short axis views of the left ventricle in hypertrophic cardiomyopathy.

Short axis views of the left ventricle were studied in 68 patients with hypertrophic cardiomyopathy (HCM) and 20 healthy persons using cross-sectional echocardiography. Configurations of the short axis view of the left ventricular cavity at the level of the papillary muscles in HCM were classified into 2 types, dumbbell and mushroom, which were formed by the position of papillary muscles. Antrior dislocation of the papillary muscles was seen in the dumbbell type, and marked hypertrophy of the papillary muscles in the proper position was seen in the mushroom type. Dumbbell shape (50 patients) was observed in the patients with marked hypertrophy in the basal protion of interventricular septum. Mushroom shape (18 patients) was seen in the patients with hypertrophy around the apex of the heart except for in a few patients. Areas of the papillary muscles (AP) and the left ventricular cavity (ALV) were measured and AP/ALV + AP ratio was calculated. The AP/ALV + AP ratio in HCM was significantly larger than that in the healthy persons, but no difference was seen between these 2 groups of HCM. It should be noted that the position of the hypertrophied papillary muscles is closely related to the distribution of hypertrophy in HCM.

Adult↗
PubMedDate not supplied

Emergent right coronary artery thrombectomy with a jet aspiration thrombectomy catheter.

A saline-jet aspiration thrombectomy (JAT) catheter was used in a patient with acute myocardial infarction. A right coronary arteriogram showed complete thrombotic occlusion at the proximal segment. With this catheter the thrombus was removed without complications in 5 sec. The patient underwent percutaneous transluminal coronary angioplasty and placement of a Palmaz-Schatz stent after successful thrombectomy. Thrombectomy with a JAT catheter was very useful in this patient.

Aged↗