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Biomedical subjects

R Nohara

Publications and source records attributed to R Nohara.

161 records · Page 9Linked to original sources
PubMed1983

Collateral function in early acute myocardial infarction.

The role of the collateral circulation less than 6 hours after the onset of acute myocardial infarction (MI) was evaluated in 34 consecutive patients without previous MI. There were 19 patients with and 15 without collaterals. The group was subdivided into those with nonjeopardized collaterals (group A, 14 patients) and those with jeopardized collaterals (group B, 5 patients), and the group without collaterals into those with partially obstructed coronary arteries (group C, 5 patients) and those with totally obstructed coronary arteries (group D, 10 patients). These groups had similar sites of coronary stenoses and MI. Eleven of 14 collaterals in group A were poor, but MI mass measured by peak creatine kinase (CK) was smaller in group A than in group B (p less than 0.01) or group D (p less than 0.01), and cardiac function was significantly better in group A than in group D (cardiac index, p less than 0.05; stroke index, p less than 0.01; ejection fraction, p less than 0.01; regional wall motion, p less than 0.01). Group C was not statistically different from group A in myocardial function and CK. Group B was similar to group D in MI mass and cardiac function (cardiac index, stroke index, ejection fraction and regional wall motion). Thus, patients with nonjeopardized collaterals and those with partially obstructed coronary arteries had less myocardial damage and better cardiac function than did those with jeopardized collaterals and those with totally obstructed coronary arteries. A nonjeopardized collateral circulation may play a role in limiting MI mass and preserving myocardial function in the early stages of acute MI.

Adult↗
PubMed1983

Effects of coronary artery reperfusion on relation between creatine kinase-MB release and infarct size estimated by myocardial emission tomography with thallium-201 in man.

The quantitative relations between serum creatine kinase-MB isoenzyme (CK-MB) release and the final infarct size estimated by myocardial emission computed tomography with thallium-201 was assessed in 37 patients with a first acute transmural myocardial infarction who underwent intracoronary thrombolysis using urokinase 4.6 +/- 1.9 hours after the onset of symptoms. Serial CK-MB determinations were used to calculate the accumulated release of CK-MB (sigma CK-MB). Myocardial emission tomography with thallium-201 was performed 4 weeks after the onset, and infarct volume was measured from reconstructed tomographic images by computerized planimetry. The results are presented for two groups of patients: 11 patients with unsuccessful thrombolysis (group A) and 26 patients with successful thrombolysis (group B). An excellent linear relation was found for group A (sigma CK-MB = 6.4 X infarct volume + 47.7, r = 0.91), whereas a different linear relation was observed for group B (sigma CK-MB = 10.5 X infarct volume + 89.1, r = 0.80). Moreover, serum CK-MB activity reached a peak at 21.1 +/- 2.2 hours after the onset in group A and reached an earlier peak at 12.5 +/- 2.9 hours in group B (p less than 0.001). These data suggest that acute coronary recanalization alters the kinetics of CK-MB release, resulting in greater CK-MB release into the serum for equivalent infarct volume estimated by myocardial emission tomography with thallium-201. Thus, serum CK-MB time-activity curves after acute myocardial infarction may be influenced considerably by acute reperfusion, which is an important factor that should be incorporated in the interpretation of enzymatic estimates of infarct size in human patients.

Adult↗
PubMed1983

Giant coronary-to-bronchial arterial anastomosis complicated by myocardial infarction.

A patient with giant extracardiac coronary anastomosis connecting the proximal right coronary artery and the right bronchial artery of the right middle and lower lobes had an inferior myocardial infarction. The pulmonary arteries were hypoplastic and those of the right middle and lower lobes were completely occluded. Left pulmonary arteries were also diffusely hypoplastic. Furthermore, this patient with rare coronary-to-bronchial arterial anastomosis and pulmonary arterial occlusion suffered from inferior myocardial infarction in the distal area of the anastomosis. This appears to be the first case of myocardial infarction reported in this type of anomaly.

Adult↗
PubMed1983

[Stress thallium-201 myocardial emission CT: comparative evaluation with coronary arteriography and left ventriculography].

Thallium-201 emission computed tomography (ECT) using a rotating gamma camera was performed during stress and redistribution phases in 70 cases admitted for cardiac catheterization. A series of transaxial, ventricular short-axis, and long-axis sections were reconstructed, and segmental analysis was performed to predict individual coronary artery involvement. A perfusion defect was observed in 54 of 57 cases with coronary artery disease (95%). Ninety of 108 diseased coronary arteries (83%) were correctly identified (91% of single-vessel disease, 82% of two-vessel disease and 80% of three-vessel disease). No significant perfusion defect was seen in 11 of 13 cases with normal coronary arteries (specificity 85%). Number of diseased coronary arteries was accurately predicted in 78% of those with single-vessel disease, 65% of those with two-vessel disease and 47% of those with three-vessel disease, indicating relatively poor accuracy for predicting multivessel disease. The sensitivity for detecting individual coronary artery involvement was 90% for the right coronary artery (RCA), 89% for the left anterior descending artery (LAD) and 67% for the left circumflex artery (LCX). The specificity was 87%, 91%, and 100%, respectively. Even in those with three-vessel disease, a perfusion defect was seen in 82% of RCA and LAD segments, and 76% of LCX segment. Thus, there were high sensitivity and specificity for detecting individual coronary involvement by ECT imagings. Segmental analysis of ECT imagings was comparatively performed with the findings of contrast ventriculography. Normal wall motion was seen in 95% of normally perfused myocardial segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1982

[Evaluation of left ventricular diastolic chamber stiffness by the apexcardiogram and echocardiogram].

This study was made to evaluate left ventricular (LV) chamber stiffness noninvasively utilizing the apexcardiogram and echocardiogram. Subjects were 13 patients with left ventricular hypertrophy (LVH) and 17 patients without LVH. Cardiac catheterization and LV angiography were also performed in all patients. In the apexcardiogram, as shown in Figs. 1 and 2, the ratios of an amplitude to the total amplitude were measured at the onset of left atrial systole (H1) (80 msec after the onset of the P wave) and the peak of A wave (H2). In the echocardiogram, LV internal diameters were determined at 80 msec after the onset of the P wave (D1) and the peak of the R wave of ECG (D2). In addition left ventricular volumes, V1 and V2, were calculated by D1 and D2 using Teichholz's method. Increments of the ratio of an amplitude of the ACG wave (delta H = H2-H1) and LV volume changes (delta V = V2-V1) which are associated with left atrial systole were calculated. The ratio of delta H to delta V (delta H/delta V) was defined as a measure of LV diastolic chamber stiffness. On the other hand, various parameters (delta P/delta V, K, dV/dP, dV/VdP) which represent LV diastolic properties were determined by LV pressure curves and LV cineangiograms. delta H/delta V by noninvasive method showed good correlations with delta P/delta V (r = 0.83), K (r = 0.68), dV/dP (r = -0.80) and dV/VdP (r = -0.75), respectively. The correlations were much better between delta H/delta V and these parameters than between A/Eo and these parameters. Patients with LVH had much greater diastolic stiffness (delta H/delta V = 2.03 +/- 1.10) than those without LVH (delta H/delta V = 0.60 +/- 0.29, p less than 0.01). It is concluded that delta H/delta V obtained from ACG and the echocardiogram is a useful parameter to evaluate LV diastolic chamber stiffness noninvasively and this ratio is well correlated with LVH.

Adolescent↗
PubMedDate not supplied

Significance of myocardial uptake of iodine 123-labeled beta-methyl iodophenyl pentadecanoic acid: comparison with kinetics of carbon 11-labeled palmitate in positron emission tomography.

BACKGROUND: A radioactively labeled beta-methyl branched fatty acid analog, 123I-15-(p-iodophenyl)-3-methyl pentadecanoic acid (BMIPP), has been developed to probe regional myocardial fatty acid metabolism. However, the significance of BMIPP uptake in the myocardium remains unclear. METHODS AND RESULTS: To evaluate the significance of BMIPP uptake, single-photon emission computed tomography was performed 30 minutes after injection of BMIPP, and 201Tl-labeled single-photon emission computed tomography was taken on a separate day in 10 patients. Findings of BMIPP and 201Tl-labeled imaging were compared with the data obtained from positron emission tomography with 11C-labeled palmitate. The BMIPP uptake (percent of maximum) was significantly correlated with the early uptake (percent) and delayed uptake (percent) of 11C-labeled palmitate (r = 0.659 and r = 0.687, respectively) (p < 0.01 each), whereas it was not significantly correlated with the residual fraction (r = 0.205) or the clearance half-time of the early component (r = 0.138) of 11C-labeled palmitate as a marker of beta-oxidation of the fatty acid. CONCLUSIONS: These data indicate that, although the myocardial uptake of BMIPP may not directly reflect beta-oxidation of fatty acids, its uptake may reflect both regional myocardial blood flow and fatty acid extraction.

Adult↗
PubMedDate not supplied

Combined assessment of regional perfusion and wall motion in patients with coronary artery disease with technetium 99m tetrofosmin.

BACKGROUND: Technetium 99m tetrofosmin is a new 99mTc-labeled myocardial perfusion agent that can be labeled easily and provides excellent myocardial perfusion images. In addition, bolus administration of the tracer allows first-pass radionuclide ventriculography. METHODS AND RESULTS: This study examined the diagnostic value of combined assessment of regional perfusion by tetrofosmin tomography and wall motion by first-pass radionuclide ventriculography both at rest and during stress in 24 patients suspected of having coronary artery disease. All patients underwent stress-rest tetrofosmin tomography, stress-delayed thallium 201 tomography, and coronary angiography. Stress tetrofosmin tomography showed abnormal perfusion in all 23 patients with angiographic evidence of coronary artery disease, whereas stress 201Tl tomography showed abnormal perfusion in 22 of the 23 patients. For detection of significant (> or = 50% diameter stenosis) stenotic coronary arteries, the two perfusion studies showed similar sensitivities (62% with 201Tl and 69% with tetrofosmin) and specificities (88% and 100%, respectively). When analysis of regional wall motion was combined with perfusion study, a slightly higher sensitivity was obtained (77%), with similar specificity. The regional wall motion score was concordant with the regional perfusion score in only 42% of the segments at rest and 50% during exercise. CONCLUSIONS: These results suggest that stress tetrofosmin perfusion tomography and stress 201Tl tomography provided similar diagnostic accuracy for detection of coronary artery disease. The combined assessment of perfusion and function that is feasible with tetrofosmin may enhance diagnostic accuracy in patients with coronary artery disease.

Aged↗
PubMedDate not supplied

Evaluation of myocardial infarct size in rat heart by pinhole SPECT.

BACKGROUND: High-resolution single photon emission computed tomography (SPECT) with a pinhole collimator is a new method for evaluating the regional properties of radiopharmaceuticals in small laboratory animals in vivo. Although several reports of normal images of rat taken by this new technique are available, there are as yet few reports on its use in disease models, such as myocardial infarction. In this study, we clearly visualized myocardial flow in the rat heart with myocardial infarction using this system, and evaluated the relationship between SPECT images and histologic analysis. METHODS AND RESULTS: For visualization of myocardial flow in rat heart, 201Tl images were taken just before and 24 days after left coronary artery ligation. The images were taken using a 4-head SPECT scanner with pinhole collimators. The percent infarct size on 201Tl-SPECT imaging (%SI) and the defect score were then assessed and compared with the percent infarct size on histologic analysis (%HI). Both the %SI and defect score correlated well with %HI (r = 0.97 and 0.74, respectively). CONCLUSION: Serial SPECT imaging using pinhole collimators permits estimates of myocardial flow even in small laboratory animals noninvasively in vivo.

Animals↗
PubMedDate not supplied

Serial evaluation of fatty acid metabolism in rats with myocardial infarction by pinhole SPECT.

BACKGROUND: Iodine 123-labeled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) is mainly trapped in the myocardium as triglyceride, depending on the adenosine triphosphate level. Ten percent to 20% of it is metabolized through alpha-oxidation after beta-oxidation; however, the precise mechanism of the regulatory pathways of BMIPP is yet to be clarified. METHODS AND RESULTS: A brief left coronary artery occlusion (10-30 minutes) was performed in 28 male Wistar-Kyoto rats. Dual single photon emission computed tomography images of BMIPP and thallium 201 were obtained 3 days and 24 days after the operation. The activities of 3-hydroxyacyl-coenzyme A dehydrogenase (HAD), citrate synthase (CS), and alpha-glycerol-phosphate dehydrogenase (GPD) were then measured in both ischemic and nonischemic regions. BMIPP and Tl-201 chloride severity scores were also evaluated conventionally. CS and HAD levels were significantly lower in the ischemic region than in the nonischemic region in the chronic group (CS, 102.9 +/- 28.1 vs 138.7 +/- 33.7 micromol/g/min, respectively, P =.0051; HAD, 54.7 +/- 20.1 vs 78.6 +/- 18.7 micromol/g/min, respectively, P =.0031). There was no difference in GPD between the ischemic and nonischemic regions. The BMIPP severity score had closer inverse relations with HAD (acute, r = -0.82; chronic, r = -0.80) and CS (acute, r = -0.87; chronic, r = -0.81), but not with GPD, than did Tl-201 chloride severity score. CONCLUSIONS: BMIPP imaging correlates well with the activities of HAD and CS, suggesting that a decrease in BMIPP uptake reflects deterioration of both fatty acid metabolism and citrate cycle and shows information other than regional myocardial perfusion.

3-Hydroxyacyl CoA Dehydrogenases↗