Biomedical subjects
Publications and source records attributed to M Yamamuro.
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The clinical usefulness of radionuclide ventriculography (RNV) was evaluated in patients with right ventricular ischemia. The subjects consisted of 25 patients with acute inferior myocardial infarction, 19 patients with old myocardial infarction and six patients with angina pectoris who had severe stenosis of the right coronary artery. In patients with acute inferior myocardial infarction, follow-up radionuclide studies were performed during the recovery periods on the first, 7th-14th, and 30th hospital day. Fifteen of the 25 patients initially had decreased right ventricular ejection fractions (evidence of right ventricular infarction). The mean value was 28 +/- 8% on the initial day, but 7-14 days and 30 days after the acute attack, it improved markedly to 36 +/- 9% and 39 +/- 9%, respectively. Regional wall motion abnormality resolved in 10 of the 15 patients on the 30th hospital day. In 25 patients with old myocardial infarction or with angina pectoris, RNV was performed at rest and during supine exercise to determine the influence or right coronary artery disease. Right ventricular ejection fraction was changed by exercise from 42 +/- 7% to 44 +/- 10% in patients with proximal artery lesions, and from 45 +/- 7% to 50 +/- 10% in patients with distal artery lesions. Right ventricular ejection fraction increased in patients with isolated right coronary artery disease (rest: 44 +/- 8%, exercise: 49 +/- 9%), decreased in patients with combined left anterior descending artery disease (rest: 40 +/- 6%, exercise: 38 +/- 11%) and increased in patients with combined circumflex artery disease (rest: 43 +/- 5%, exercise: 47 +/- 6%). We concluded that right ventricular infarction is a frequent complication in patients with inferior myocardial infarction. However, right ventricular ejection fraction and right ventricular regional wall motion abnormality improve dramatically within one month. Stress-induced ischemia would be rare in patients with isolated right coronary artery disease. The above findings support the notion that the right ventricular myocardium has peculiar coronary perfusions.
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In this study, the clinical utility of phase analysis using gated blood pool scintigraphy to detect aortic regurgitation (AR) was assessed. The study population included 33 patients with AR documented by cineaortography, and 53 patients without AR diagnosed by clinical features and pulsed Doppler echocardiography or cineaortography. Gated blood pool images were stored in modified left anterior oblique views by the multiple gated method (28 frames per beat) after the in vivo labeling of erythrocytes using 25 mCi 99m-Tc. Amplitude was depressed at the subaortic region toward the apex in patients with AR, and occasionally the phase angle occurred earlier in the same region. This is because diastolic filling began earlier and stroke count was decreased more in the subaortic region than in other regions of the left ventricle in examining the regional time-activity curve. Based on this characteristic finding in the amplitude image, the specificity was 81% and the sensitivity was 79% in the diagnosis of AR. The degree of AR was estimated using the amplitude image as follows: grade 1, depression of amplitude localized to the subaortic region; grade 2, depression of amplitude detected from the subaortic region to the midportion of the left ventricle; grade 3, depression of amplitude detected beyond the midportion of the left ventricle. We compared results with those of the radionuclide (RI's classification) and angiographic methods (Sellers' classification) as to the severity of AR. AR could not be detected using the radionuclide method in all four patients with Sellers' grade 1, and in three of nine patients with Sellers' grade 2.(ABSTRACT TRUNCATED AT 250 WORDS)
For 52 patients with cardiac disease and 11 patients with vascular disease, In-111-oxine platelet scintigraphy was performed to assess its clinical usefulness for detecting thrombi. Using Hayashida's method, platelets were separated in 43 ml peripheral blood, washed and labeled with 1 mCi In-111-oxine. In addition to planar images in the anterior, 45 degrees left anterior oblique and left lateral views, single photon emission computed tomography (SPECT) was performed in some cases by rotating a dual gamma camera 24 and 72 hours after labeled platelet injection. The functions of platelet and coagulability were examined 36 hours after the injection of labeled platelets. Medical therapy was not changed during this study. Intracardiac thrombi were documented in 16 of 52 cases with cardiac disease and intravascular thrombi in 10 cases with vascular disease by angiography, CT and two-dimensional echocardiography. Positive images were obtained in 10 cases with cardiac disease and in eight cases with vascular disease by scintigraphy. Therefore, sensitivity, specificity, and overall accuracy were 63%, 100% and 88% in intracardiac thrombi; 80%, 100% and 82% in intravascular thrombi; and totally 69%, 100% and 87%, respectively. In the detection of intracardiac thrombi by scintigraphy, the sensitivity seemed to be lower and the specificity higher than those by other graphic studies. In 52 cases with cardiac disease, five out of six cases with false negative images had received antiplatelet and/or anticoagulant drugs, and in these cases, platelet and coagulation functions tended to be decreased compared with those of true positive cases or true negative cases. We conclude that positive images in scintigraphy indicate the existence of growing thrombi, and that In-111-oxine platelet scintigraphy has clinical usefulness, not only for detecting thrombi, but for estimating platelet activity and effect of medical therapy.
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A technique employing a nerve stimulator and an insulated needle was used for supraclavicular brachial plexus block in 71 patients using 0.5% plain bupivacaine 15-20 ml. The mean minimal stimulating current to produce paraesthesia was 0.09 mA. The plexus was identified at a mean depth of 27 mm below the skin. The block was successful in 98% of patients when the stimulation was felt in the index, middle or ring finger, but was often incomplete when felt in the thumb or little finger.
The effect of indomethacin, a prostaglandin (PG) synthesis inhibitor, on the hemodynamics and survival rates of Escherichia coli endotoxin-administered animals (dog and Rat) was studied. Indomethacin post-treatment significantly elevated aortic pressure, cardiac output, and left ventricular isometric tension elevated aortic pressure, cardiac output, and left ventricular isometric tension rise (LVP dp/dt max) following endotoxin administration in the dog. In dogs in a hyperdynamic state due to indomethacin administration treated with phenoxybenzamine (COB) and alprenolol, aortic pressure and cardiac output fell to pre-indomethacin administration values. In reserpine-administered and bilaterally adrenalectomized dogs, hemodynamic states were not altered by indomethacin administration during endotoxin shock. These results suggest that indomethacin potentiates the responses of catecholamines induced by endotoxin shock. Pretreatment with indomethacin alone did not increase the survival rates in endotoxin-administered rats. However, pretreatment and posttreatment with indomethacin combined with POB significantly increased the survival rate over untreated controls (LD 80) given endotoxin alone. Cyclic adenosine monophosphate (cAMP) levels in liver tissue decreased significantly in untreated controls and rats pretreated with indomethacin alone. In contrast, tissue cAMP levels remained within normal values in rats pretreated with indomethacin combined with POB. These results indicate that indomethacin may make a significant contribution as an antishock agent when peripheral circulation is maintained.
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