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Biomedical subjects

K Kadota

Publications and source records attributed to K Kadota.

At least 181 records · Page 10Linked to original sources
PubMed1984

Clinical evaluation of 99mTc-pyrophosphate myocardial emission computed tomography: comparison with planar imaging.

To depict the three-dimensional distribution of 99mTc-pyrophosphate in the heart, emission computed tomography (ECT) was performed, following the conventional planar imaging, in 32 cases with suspected acute myocardial infarction (AMI). There were 23 cases with evidence of AMI, 7 with unstable angina (UA), and 2 with dilated cardiomyopathy (DCM). While the planar images showed discrete cardiac activity in only 11 of the 23 cases (48%) with AMI, the ECT images delineated focal myocardial uptake clearly in 20 of them (87%). On the other hand, the ECT images revealed cardiac blood-pool activity without significant myocardial uptake in all cases with UA and DCM in which the planar images showed diffuse activity. Thus, the ECT imaging of 99mTc-pyrophosphate seems to be a valuable technique for assessing the presence and localization of myocardial necrosis, especially in cases showing diffuse cardiac activity in the planar imaging.

Adult↗
PubMed1984

Stress thallium-201 transaxial emission computed tomography: quantitative versus qualitative analysis for evaluation of coronary artery disease.

Stress thallium-201 myocardial distribution was quantitatively evaluated by emission transaxial tomography in 104 patients who underwent coronary arteriography. The initial uptake and percent washout of thallium were assessed by the circumferential profile curves of the three short-axis sections and one middle right anterior oblique long-axis section. This quantitative tomographic analysis showed abnormal distribution in all but two patients (98%) with coronary artery disease, whereas qualitative analysis showed abnormality in 76 of the patients (93%). Quantitative analysis showed better sensitivity (91%) for detecting involved coronary vessels than qualitative analysis (80%, p less than 0.01), especially in three vessel disease (82 versus 67%, p less than 0.05). For localization of individual vessel involvement, quantitative analysis showed high sensitivity (right coronary artery: 96%, left anterior descending artery: 90% and left circumflex artery: 88%) as compared with qualitative analysis (88, 83 and 63%, respectively, p less than 0.05), while similar specificity was observed (92% for quantitative and 93% for qualitative analyses). Furthermore, in the study of patients without infarction, myocardial segments supplied by coronary vessels with moderate stenosis (51 to 75%) revealed abnormality more often with quantitative (81%) than with qualitative (56%) analysis. Thus, quantitative analysis of stress thallium emission tomography provides improved sensitivity for the detection of diseased coronary vessels in patients with three vessel disease and those with moderate stenosis. It is a valuable technique for the evaluation of coronary artery disease.

Cardiac Catheterization↗
PubMed1984

Emission computed tomography with technetium-99m pyrophosphate for delineating location and size of acute myocardial infarction in man.

Emission computed tomography with technetium-99m pyrophosphate was used to delineate the location and estimate the size of myocardial infarcts in 20 patients with documented acute myocardial infarction. Tomography was performed after planar imaging within 2-5 days after the onset of infarction. A series of transaxial, frontal, and sagittal tomograms were reconstructed from 32 views imaged from the left side of the patient's chest with a rotating gammacamera. Infarct volume was measured from the tomographic images by computerised planimetry and was compared with the cumulative release of creatine kinase MB isoenzyme. The planar images showed discrete myocardial uptake in 13 of the 20 patients and diffuse uptake throughout the cardiac region in the remaining seven. In contrast, the tomographic images clearly delineated discrete myocardial uptake by avoiding confusion of myocardial activity with that of surrounding structures, particularly bones, in all patients. For the 10 patients whose infarct size was assessed by analysis of the creatine kinase MB curve there was a close correlation between infarct volume estimated by tomography and by cumulative creatine kinase MB release. Thus emission computed tomography can provide a three dimensional map of technetium-99m pyrophosphate distribution within the heart and is thus able accurately to localise and estimate the size of myocardial infarcts in man.

Adult↗
PubMed1984

Improved detection of myocardial infarction by emission computed tomography with thallium-201. Relation to infarct size.

Emission computed tomography with thallium-201 was compared with planar imaging in its ability to detect myocardial infarctions of various sizes four weeks after the onset. Tomography was performed after planar imaging at rest in 160 patients with a first myocardial infarction, in whom infarct size was prospectively estimated by the peak value of creatine kinase activity at the time of the acute episode and in 39 patients without infarction. The planar images and the transaxial, short axial, and long axial tomograms were interpreted qualitatively. Tomography was significantly more sensitive than planar imaging in detecting anterior (87% v 96%), inferior (73% v 97%), and non-transmural (47% v 87%) infarcts. The increased sensitivity was confined to detecting small infarcts as assessed by the peak creatine kinase value (44% v 89% when peak creatine kinase activity was less than or equal to 1000 IU/l). The overall sensitivity was 96% for tomography and 78% for planar imaging. The specificity was similar (92%) with the two techniques. Thus emission computed tomography can improve the detection rate of small infarcts that cannot be identified on planar images, by showing the three dimensional distribution of thallium-201, and increases the diagnostic value of thallium-201 scintigraphy.

Adult↗
PubMed1984

Effect on exercise tolerance and pharmacokinetics of conventional and sustained release preparations of propranolol in patients with angina pectoris--a double-blind cross-over study.

Ten patients with effort angina were studied in a randomized double-blind cross-over trial in order to investigate the effect of sustained release propranolol (LA) and conventional propranolol (Prop) formulations on exercise tolerance. LA was given once daily and Prop three times daily. Treadmill exercise tests were performed using the Bruce protocol and the plasma propranolol levels were measured. The following results were obtained: LA proved to have an anti-anginal effect similar to Prop. No adverse reactions were observed after administration of either of the drugs. Similar suppressive effect of the heart rate, blood pressure and double product at rest and on exercise was seen after LA and Prop while the exercise capacity was increased. The plasma level of propranolol was higher at 2 hours after Prop than LA administration, but there was no difference between LA and Prop at 4 and 24 hours after administration. The plasma propranolol level at 4 hours after LA correlated with the percent reduction in exercise heart rate and with the percent reduction in the double product. Our study suggested that once-a-day administration of LA could improve patients' compliance and adds another choice to the list of clinically useful beta-blockers for the treatment of angina pectoris on effort.

Aged↗
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

Multiaxial tomography of heart chambers by gated blood-pool emission computed tomography using a rotating gamma camera.

Fifteen patients and three volunteers underwent radionuclide blood-pool cardiac studies with electrocardiographic gating. Following conventional planar-gated imaging (anterior and left anterior oblique projections), emission computed tomography (ECT), using a rotating gamma camera, was performed. A series of transaxial tomograms of the cardiac chambers was obtained. The left ventricular short-axis plane, long-axis plane, and four-chamber-view plane were then reorganized; each chamber was visualized separately. Compared to gated planar imaging, this technique showed regional asynergy more clearly in patients with myocardial infarction and demonstrated dilatation of the atria and ventricles more accurately in patients with an atrial septal defect and valvular heart diseases. In addition, when a section of the heart is obtained at any angle with gated blood-pool ECT, three-dimensional assessment of cardiac chambers in motion is more precise; mutual superimposition becomes unnecessary.

Adult↗
PubMed1983

Radiocardiographic assessment of dobutamine and isosorbide dinitrate therapy in patients with mitral stenosis and pulmonary congestion.

Simultaneous hemodynamic and radiocardiographic measurements were performed on 10 patients with mitral stenosis and pulmonary congestion for evaluating the acute effects of dobutamine (DB, 5 micrograms/kg/min), isosorbide dinitrate (ISD, 10 mg sublingually) or a combination of the two. DB alone produced a significant increase of the cardiac index (CI) from 2.9 +/- 0.1 to 3.7 +/- 0.2 L/in/m2 (p less than 0.01), but a modest increase in pulmonary artery diastolic pressure (PADP) and in pulmonary blood volume by approximately 15%, respectively. ISD alone caused a decline in PADP from 26 +/- 2 to 18 +/- 1 mmHg (p less than 0.001), in right heart volume from 300 +/- 36 to 215 +/- 18 ml/m2 (p less than 0.05) and in left heart volume from 321 +/- 28 to 248 +/- 20 ml/m2 (p less than 0.05), but no change in the CI. Combined administration of the two agents resulted in favorable alterations in both hemodynamic variables: PADP decreased from 26 +/- 2 to 20 +/- 1 mmHg (p less than 0.01) and the CI increased from 2.9 +/- 0.1 to 3.3 +/- 0.1 L/min/m2 (p less than 0.05). Thus, DB alone had a tendency to aggravate pulmonary venous congestion in our patients, while ISD is effective in reducing the congestive manifestations of heart failure due to its venodilating effects but less beneficial in increasing the CI. The combined therapy of DB and ISD appears to be extremely effective in restoring an adequate cardiac output and in relieving the symptoms of pulmonary vascular congestion in the presence of mitral stenosis.

Adult↗
PubMed1983

Unstable angina--clinical course and medical management including antiplatelet treatment.

One hundred patients with unstable angina who were treated medically were classified into 2 groups of non-crescendo and crescendo angina and reviewed regarding their clinical course for 24 months on the average. Thirty-four patients with non-crescendo angina had an occurrence of recurrent angina in 7 patients (21%), myocardial infarction in 2 (6%) and death in none, while 66 patients with crescendo angina had a significantly higher occurrence of recurrent angina in 29 (44%) and myocardial infarction in 14 (21%), p less than 0.05 in both angina and infarction. There were 4 (6%) deaths in patients with crescendo angina in spite of similar clinical backgrounds. Modern medical treatments of unstable angina include nitrates, beta blockers, calcium antagonists as well as antiplatelet and thrombolytic therapy. We conclude that our patients under active medical treatment have more favorable prognosis than once thought and that classification of unstable angina into non-crescendo and crescendo angina according to the early clinical course appears to be useful both for a selection of treatments and for an assessment of prognosis.

Adenosine Diphosphate↗
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↗