Development of a highly efficient implanted thermal ablation device: in vivo experiment in rat liver.

OBJECTIVES: To evaluate an implanted thermal ablation device that can be heated with high efficiency using a resonant circuit as the implant. METHODS: 16 rats were used. The implants, adjusted at a resonance frequency of 4 MHz, were fixed on the surface of the liver of rats under laparotomy. In 14 of 16 rats, an alternating magnetic field (AMF) was applied for 6 min with an output of 300 W from outside the body using a ferrite core applicator. The implant temperature during AMF exposure was measured. The 14 rats were divided into 5 groups, depending on time from AMF application until they were sacrificed (1 h, 1 day, 3 days, 7 days and 1 month after application). Two rats not exposed to AMF were used as controls. Livers were removed and evaluated; the cross-sectional area and width of the ablated region were measured. RESULTS: During AMF exposure, the implant temperature rose to 127.8±39.3 °C (mean±standard deviation). The cross-sectional area of the ablated region was largest after 1 day and tended to decrease with time. The widths of the ablated region were 4.87±0.22 mm, 4.15±0.36 mm, 3.67±0.58 mm and 3.24±0.16 mm in the 1 day, 3 day, 7 day and 1 month groups, respectively. No significant differences (p<0.05) were seen in either cross-sectional area or width of the ablated region. CONCLUSION: Sufficient heat for ablation was obtained in vivo using a newly developed implanted thermal ablation device. This device may be a new option for thermal ablation therapy.

Effect of antenatal dexamethasone treatment on Ca2+-dependent nitric oxide synthase activity in rat lung.

We investigated the effects of dexamethasone on nitric oxide synthase activity, nitrate/nitrite concentration, and cGMP concentration in the lungs of premature and full-term neonate rats. Dexamethasone or vehicle alone was administered to the mother (1 mg/kg/d, s.c., 2 d), and the neonate was killed 24 h after birth. Ca2+-dependent nitric oxide synthase activity and nitrate/nitrite and cGMP concentrations in lungs of dexamethasone-treated neonates, both premature and full-term, were significantly higher than those in the lungs of the control rats. Ca2+-dependent nitric oxide synthase activity, nitrate/nitrite concentration, and cGMP concentration in the lungs of control rats showed developmentally associated increases during late gestation and in the early postnatal period. The activation of the nitric oxide synthasenitric oxide-cGMP system by antenatal dexamethasone treatment may be related to the improvement of pulmonary function by antenatal glucocorticoid therapy to minimize respiratory distress syndrome.

Conformational studies on the four stereoisomers of the novel anticholinergic 4-(dimethylamino)-2-phenyl-2-(2-pyridyl)pentanamide.

To interpret differences in the anticholinergic activity among the four stereoisomers of 4-(dimethylamino)-2-phenyl-2-(2-pyridyl)pentanamide (1-4), we performed conformational studies using the semiempirical molecular orbital method. The structures of the global minimum-energy conformations obtained for 1-4, however, could not explain the different activities, particularly in terms of distances between the essential pharmacophores. We thus implemented superimposition studies, using the energetically stable conformations of the most active stereoisomer, 1(2S,4R), as a template. The energy penalties for a conformation change of the less active stereoisomers 2-4 from their global minimum-energy structure to a new conformation, fitting onto the global minimum-energy conformation of 1, appear to account for the differences in the pharmacological potency better than using the other conformations of 1 as a template. We thus presume that the global minimum-energy conformation of 1 is closely related to the bioactive conformation for these anticholinergics, and also that the pharmacological potency is linked to how readily these substances can change their conformations to fit the muscarinic receptor.

[Myocardial imaging with 123I-metaiodobenzylguanidine (123I-MIBG) in essential hypertension: does the 123I-MIBG imaging have the ability to predict its prognosis?].

To study myocardial norepinephrine (NE) activity in essential Hypertension 9HT) and to clarify its prognostic significance, we performed myocardial imaging with 123I-metaiodobenzylguanidine (123I-MIBG) and 201Tl at rest in 16 patients with HT and 9 normal subjects. In addition to ordinary tomograms, whole body images were obtained in both 123I-MIBG and 201Tl imaging. From the whole body image, a ratio of myocardial radionuclide accumulation to total injected dose was calculated (%Uptake). And Uptake Ratio (%Uptake of 123I-MIBG/%Uptake of 201Tl) was used as an index of myocardial 123I-MIBG uptake. Reduction of myocardial 123I-MIBG during 3 hours was calculated and expressed as washout rate (WOR). From the Bull's-eye map, the extent of defect was quantitatively assessed (Defect Score) and the homogeneity of the radionuclide distribution within the myocardium (CV) was calculated. In 123I-MIBG imaging, defect appeared in 12 patients with HT (75%), but in normal subject no one showed defect. Patients with HT were divided into two groups according to left ventricular ejection fraction (EF) responses to exercise stress which were obtained by 99mTc blood pool imaging. Group 1 consisted of 8 patients who showed EF elevation (5-10%) by exercise and group 2 consisted of 6 patients with depression of EF (-4-6%) by exercise. Rest EF, peak filling rate, exercise heart rate, exercise blood pressure and left ventricular mass were identical between two groups. Uptake Ratio in Group 2 (0.67 +/- 0.04) was significantly smaller (p < 0.05) than those in Group 1 (0.75 +/- 0.05) and normal subject (0.75 +/- 0.06). And in Group 2, WOR of 123I-MIBG was greater than that of Group 1. In Group 2, defect of 123I-MIBG appeared in all patients, but in Group 1 defect developed in 50%, besides Defect Score was significantly greater in Group 2 than in Group 1 (3.8 +/- 1.4 vs. 1.5 +/- 1.8, p < 0.05). The unhomogeneity of 123I-MIBG distribution was significantly greater in Group 2 (CV; 30 +/- 5%) than in Group 1 (21 +/- 4%) and in normal subjects (18 +/- 4%). These results suggested that quantitative analysis of 123I-MIBG imaging may be helpful for assessing the prognosis of HT.

[Quantitative analysis of 123I-metaiodobenzylguanidine myocardial imaging: assessment of its usefulness in patients with congestive heart failure].

To investigate the usefulness of the quantitative analysis of 123I-metaiodobenzylguanidine (123I-MIBG) myocardial uptake, we studied 9 normal subjects and 18 patients with congestive heart failure (CHF). Rest myocardial imaging with 123I-MIBG was performed at 20 minutes and 3 hours (delayed image) after 123I-MIBG injection. Rest 201Tl imaging was obtained at 20 minutes after 201Tl injection. In addition to ordinary tomograms, a planar anterior image and a whole body image were supplemented in each imaging. In patients with CHF fractional shortening (%FS) was calculated from echocardiography and left ventricular ejection fraction was obtained from cardiac blood pool imaging with 99mTc at rest. We calculated H/M (heart to mediastinum count ratio) from the anterior planar image and %Uptake (percentage of cardiac uptake of the isotope to total injected dose) from the whole body image. H/M of 123I-MIBG in delayed images separated patients with CHF from normal subjects (2.00 +/- 0.19 vs. 2.56 +/- 0.13, p < 0.01). H/M Ratio (H/M of 123I-MIBG divided by H/M of 201Tl) in delayed image could distinguish these two groups poorly (0.72 +/- 0.12 vs. 0.88 +/- 0.14, p < 0.05). On the other hand, %Uptake of 123I-MIBG was not different between two groups (3.49 +/- 0.60% in CHF, 3.54 +/- 0.34% in normal). But %Uptake of 201Tl was greater in CHF than in normal (5.96 +/- 1.09% vs. 4.70 +/- 0.30%, p < 0.05). When myocardial 123I-MIBG uptake was normalized by myocardial perfusion (%Uptake of 123I-MIBG divided by %Uptake of 201Tl, Uptake Ratio), Uptake Ratio in delayed image could distinguish theses two groups as same as H/M (0.60 +/- 0.05 in CHF, 0.75 +/- 0.05 in normal, p < 0.01). In patients with CHF, H/M of 123I-MIBG did not reflect LV function and serum norepinephrine (NE) level. But Uptake Ratio and H/M Ratio in delayed image correlated well with %FS (r = 0.88, r = 0.65), EF (r = 0.80, r = 0.68) and NE level (r = -0.77, r = -0.75). Although the calculation of Uptake Ratio is time consuming and expensive, it was assumed that Uptake Ratio is an useful index to quantitate myocardial 123I-MIBG uptake.

CS-045, a new oral antidiabetic agent, stimulates fructose-2,6-bisphosphate production in rat hepatocytes.

Fructose-2,6-bisphosphate is a potent activator of 6-phosphofructo-1-kinase, a key enzyme in glycolysis. We previously revealed that sulfonylureas stimulate fructose-2,6-bisphosphate production in the rat liver by activating 6-phosphofructo-2-kinase. In the present study, we show that CS-045, a new antidiabetic agent, activated 6-phosphofructo-2-kinase and raised fructose-2,6-bisphosphate levels in dispersed rat hepatocytes. This action was time- and dose-dependent. Ten micromolar CS-045 raised the fructose-2,6-bisphosphate content linearly to the submaximal level in 20 min. Dose dependency was observed in the range of 1-30 microM. Thirty micromolar CS-045 completely reversed the inhibitory effect of 0.1 nM glucagon on fructose-2,6-bisphosphate production. CS-045 activated 6-phosphofructo-2-kinase by decreasing the Km value for the substrate (fructose-6-phosphate) without affecting the Vmax. The combination of suboptimal doses of CS-045 and tolbutamide increased fructose-2,6-bisphosphate content more than that induced by each agent alone. These results indicate that CS-045 may reduce plasma glucose by facilitating glycolysis in the liver.

[Assessment of myocardial viability by exercise stress-redistribution myocardial scintigraphy with thallium-201: the usefulness of C-map].

Standard exercise (Ex)-redistribution (RD) myocardial imaging with thallium-201 (201Tl) may not differentiate viable myocardium from necrosis. This study was intended to clarify whether 201Tl washout rate (WOR) abnormality after Ex can detect myocardial viability in the myocardium with perfusion defect using routine RD image. We performed Ex-RD (three hours after) myocardial tomography with 201Tl in 29 patients with coronary artery disease. From myocardial tomography, 201Tl distribution Bull's-eye maps (Ex and RD) and WOR Bull's-eye map were made. At RD image before PTCA, by referring to the original image, the activity of the myocardial region below 40% to 55% of the maximal 201Tl activity was considered as perfusion defect (RD-Map). Then we constructed a new image (C-Map) by adding the location of WOR abnormality (< or = 30%) to the RD-Map and each map was divided into 17 segments. If the defect-segment in the RD-Map corresponded to WOR abnormality, the segment in the C-Map was judged as viable (no defect). The C-Map and myocardial imaging after PTCA (Post-Map) were compared. In the RD-Map before PTCA, defect was found in 152 segments but in the C-Map they decreased to 59 segments, while defect was found in 62 segments in the Post-Map. In 23 patients the number of defect-segments in the C-Map decreased as compared with those in the RD-Map. And in 22 of them, the Post-Map showed the reduction of defect-segments in comparison with the RD-Map, but in one of them defect did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on neurokinin antagonists. 3. Design and structure-activity relationships of new branched tripeptides N alpha-(substituted L-aspartyl, L-ornithyl, or L-lysyl)-N-methyl-N-(phenylmethyl)-L-phenylalaninamides as substance P antagonists.

As an extension of our study on discovering a novel substance P (SP) antagonist, we designed new branched tripeptides containing L-aspartic acid (2 and 5), L-ornithine (3 and 6), and L-lysine (4 and 7) by reconstructing the structure of the previously reported tripeptide SP antagonist [Ac-Thr-D-Trp(CHO)-Phe-NMeBzl (1), FR113680]. The strategy for this design was based on the postulate that the dipeptide half D-Trp(CHO)-Phe-NMeBzl in 1 is essential for receptor recognition. Molecular modeling studies implied that these newly designed tripeptides could mimic the spatial orientations of the essential dipeptide structure. As expected, all of these compounds potently inhibited 3H-SP (1 nM) binding to guinea pig lung membranes in the 10(-8) M range. The 1H-indol-3-ylcarbonyl derivatives (5-7) were slightly more potent than the corresponding 1H-indol-2-ylcarbonyl derivatives (2-4), as predicted by the molecular modeling studies. The structure-activity relationships studies on the selected 1H-indol-3-ylcarbonyl derivatives indicated that the threonine moiety at the side chain can be modified into a variety of structures without any significant loss of the activity. Furthermore in the L-lysine series, even dipeptide compounds having nothing or a simple acyl group at the epsilon-amino group, such as N alpha-[N alpha-(1H-indol-3-ylcarbonyl)-L-lysyl]-N-methyl-N-(phenylmethyl)- L-phenylalaninamide (18b), exhibited potent activity. These dipeptides belong to a new structural class of SP antagonist.

[Relationship of left ventricular wall motion to myocardial viability in patients with recent myocardial infarction].

The influence of left ventricular myocardial perfusion on left ventricular wall motion in patients with recent myocardial infarction was studied to try to differentiate viable myocardium from necrotic myocardium in 21 patients with initial myocardial infarction who received successful percutaneous transluminal coronary angioplasty (PTCA) 5-8 weeks after the onset. Exercise stress myocardial tomography with 201Tl (Ex-Tl) was performed before (3-5 weeks after acute onset) and after PTCA. Myocardial images were reconstructed into a bull's eye map which was divided into 17 segments. Rest ECG-gated cardiac blood pool tomography with 99mTc was performed before PTCA, and the left ventricular wall was divided into the same 17 segments used in Ex-Tl. The % shortening in each segment was calculated. Myocardial perfusion and % shortening were compared in each myocardial segment. Myocardial perfusion was classified into 4 types by considering whether exercise induced myocardial perfusion abnormality was transient (RD(+)) or persistent (RD(-)) in delayed image; 1) normal perfusion, 2) redistribution (+); RD(+): transient or viability exercise-induced perfusion defect before PTCA, 3) RD(-)/viable: fixed defect before PTCA but normal perfusion after PTCA, and 4) necrosis: fixed defect before and after PTCA. Most normal perfusion segments (88% of 184) showed normal wall motion and mean % shortening was 42 +/- 11%. Only 13 of 73 RD(+) segments showed normal wall motion. Thirty-eight and 19 RD(+) segments showed moderate hypokinesis and severe hypokinesis or akinesis, respectively. Mean % shortening in RD(+) segments was 19 +/- 13%. Thirty-seven of 38 RD(-)/viable segments had wall motion abnormalities, and 20 showed severe hypokinesis or akinesis. Mean % shortening in RD(-) segments was 12 +/- 8%. All 62 necrosis segments showed wall motion abnormalities including 10 with dyskinesis and 42 with akinesis or severe hypokinesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Distributions of the calcitonin gene-related peptide and substance P in the monkey larynx.

The distribution of calcitonin gene-related peptide (CGRP)- and substance P (SP)-like immunoreactivity in the monkey larynx was studied with light microscopy using the immunofluorescence method. We divided the larynx into the following six regions: epiglottis, arytenoid region, false cords, ventricle, vocal cords and subglottis. The distribution of immunoreactivity in the epithelium and subepithelial layer was determined. CGRP- and SP-like immunoreactive nerve fibers were observed in all regions of the laryngeal epithelium except in the vocal cords. In the epithelium of the epiglottis and arytenoid region, numerous taste buds containing several CGRP- and SP-like immunoreactive nerve fibers were observed. In the subepithelial layer, CRGP- and SP-like immunoreactive nerve fibers were observed in all regions of the larynx. In order of decreasing density, these fibers were found in the arytenoid region (especially the corniculate tubercle), the epiglottis, the false cords, the subglottis, the ventricle, and the vocal cords. In the corniculate tubercle, CGRP- and SP-like immunoreactive nerve fibers formed a network, whereas around the cuneiform tubercle, dense CRPG- and SP-like immunoreactive nerve fibers were noted parallel to the basement membrane. SP-like immunoreactive nerve fibers showed a very similar distribution to the CRPG fibers in the epithelium and the subepithelial layer, but SP-like fibers were sparser in all regions of the larynx. These results, together with previous findings indicate that the arytenoid region and the epiglottis of the monkey larynx play very important roles in airway protection, swallowing, and respiration.

[Myocardial perfusion in patients with left bundle branch block and without coronary artery disease].

For the evaluation of myocardial perfusion in patients with left bundle branch block (LBBB), we performed exercise stress (Ex)-redistribution (RD) myocardial tomography with thallium-201 (201Tl) in 23 patients with LBBB and without coronary artery disease (CAD). Myocardial images in patients with LBBB were compared with those of 9 patients with CAD who showed Ex induced transient septal defect. Bull'-eye maps (201Tl distribution maps at Ex and RD and 201Tl washout rate [WOR] map) were made from myocardial tomograms. In 23 patients with LBBB, 15 patients (65%) developed myocardial perfusion abnormality. In 10 (67%) of these 15 patients, transient perfusion defect appeared in the entire septum (diffuse type). On the other hand in 5 patients (33%), localized fixed perfusion defect developed at the boundary between septum and anterior wall (focal type). In focal type, every patient had other disease such as hypertension, aortic stenosis or sick sinus syndrome. While in patients with diffuse type, other diseases were observed in 30% (p less than 0.05) and they were limited to hypertension or diabetes mellitus. These facts suggested that mechanisms of perfusion abnormalities might be different between these two groups. We compared the perfusion abnormality between LBBB diffuse type and CAD. The extent of the defects was not different between two groups. Although apex was included within the defect in 89% of CAD population, apical defect was observed in only 20% of diffuse type (p less than 0.05). Minimal 201Tl WOR and 201Tl uptake ratio of septum to lateral wall indicated that exercise induced septal defect was slighter in diffuse type than CAD.(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of myocardial viability by exercise stress myocardial tomography with 201Tl--the usefulness of 201Tl washout rate].

Exercise stress (Ex) and redistribution (RD) myocardial tomography with thallium-201 (Tl-201) has been widely used for evaluating myocardial viability. But recent studies have demonstrated that reinjection (ReI) study following RD study is necessary for detecting reversible ischemic myocardium. On the other hand, decreased myocardial washout of Tl-201 after Ex is an indicator of myocardial ischemia. So we have studied the usefulness of myocardial Tl-201 washout rate (WOR) for the evaluation of myocardial viability by comparing it with ReI images. Ex and RD myocardial tomographies were obtained immediately after Ex and 3 hours later. After RD study a small amount of Tl-201 was injected and ReI imaging was repeated. We studied 64 myocardial segments (in 58 patients with coronary artery disease) in which Ex-induced perfusion defects persisted in RD images. According to the changes of perfusion defects between Ex, RD and ReI images, they were classified into 3 types: Type I; perfusion defect on the RD image was identical to ReI image (75%) Type I was divided into 2 subgroups whether perfusion defect at Ex was unchanged (Ia, 42%) or improved (Ib, 33%) on the RD image. Type II; perfusion defect at Ex was reduced on the RD image and it improved furthermore at ReI image (17%). Type III; perfusion defect was the same at Ex and RD but it was reduced on the ReI image (8%). WOR less than 30% was defined as abnormal when Ex heart rate exceeded 120 bpm and lung-myocardial Tl-201 uptake ratio was less than 0.45.(ABSTRACT TRUNCATED AT 250 WORDS)

[Left ventricular function assessed by multigated blood pool single photon emission computed tomography with 99mTc].

To evaluate the usefulness of gated blood pool single photon emission computed tomography with 99mTc (gated SPECT) for assessing left ventricular function, we performed gated SPECT in 2 normal subjects and 18 patients including 13 with ischemic heart disease, 3 with hypertrophic cardiomyopathy and 2 with dilated cardiomyopathy. Left ventricular end-diastolic volume (LVEDV), left ventricular ejection fraction (LVEF) and regional wall motion obtained by gated SPECT were compared with the results of contrast left ventriculography (contrast LVG), echocardiography and planar multigated blood pool imaging (planar blood pool). After the patients' red blood cells were labelled with 30 mCi (1,110 MBq) 99mTc in vivo, gated SPECT was performed in each of 32 projections through a 360 degree arc for each of the cardiac cycle divided into 16. From these images, the left ventricular vertical long-axis image, the horizontal long-axis and short-axis images were reconstructed. To calculate LVEDV, we used serial short-axis images which were composed of the left ventricle. To define left ventricular and left atrial borders, we used amplitude images and cinematic displays of the vertical long-axis image. The level of the optimal cut for delineating the left ventricular border was determined from the volume-cut-level-graph at each background activity, which was constructed by a phantom study. Left ventricular wall motion by gated SPECT was compared with the results of contrast LVG according to segmental analysis. LVEDV obtained by gated SPECT showed an excellent linear correlation with LVEDV calculated by echocardiography (r = 0.98, p < 0.01) and by contrast LVG (r = 0.89, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

[Three-dimensional display and its quantification of exercise stress myocardial tomography using thallium-201].

For accurate and stereoscopic delineation of the location and extent of perfusion abnormality by exercise stress myocardial emission tomography using thallium-201, three-dimensional myocardial images (3D image) were reconstructed from ordinary tomograms. We also quantitated perfusion abnormality, with myocardial thickness taken into consideration. We evaluated the usefulness of these 2 methods in patients with coronary artery disease (CAD). Sixty-one patients with 75% or more narrowing of at least one of their major coronary arteries were studied. Myocardial imaging was performed with thallium-201 immediately after exercise stress, and 3 hours thereafter (redistribution) using a rotating gamma camera. We reconstructed 3 routine oblique images and bull's eye maps which included myocardial thallium-201 washout rate maps. In addition to visual interpretation, washout rate abnormality (< 30%) was used as a criterion for exercise-induced myocardial ischemia. For reconstruction of 3D image, we used short-axis images. To identify the cardiac surface, an appropriate count threshold level was determined and image elements exceeding the threshold level were considered the cardiac surface. The heart was observed from 16 points around it and the brightness of the cardiac surface was adjusted in accordance with the distance between the observation point and the cardiac surface. Gradient shading was added and a stereoscopic 3D image was obtained. For the quantitative analysis of the perfusion abnormality, we selected short-axis images. By approximating each short-axis image using 2 circles which contacted the epicardial and endocardial surfaces, we readily calculated the total left ventricular myocardial voxel numbers and the perfusion abnormality voxel numbers. The ratio between these 2 parameters was expressed as % defect. The sensitivity of the 3D image for detecting CAD was 84%, which was similar to that of routine oblique images and the bull's eye method. We also detected the location and extent of perfusion abnormalities and their changes between exercise stress and redistribution in real size and stereoscopically. In patients who had initial myocardial infarction and one-vessel disease but no exercise-induced additional perfusion abnormalities, % defect correlated linearly with the left ventricular ejection fraction (r = -0.85, p < 0.005) and the peak level of the serum cardiac myosin light chain I in the acute phase of myocardial infarction (r = 0.81, p < 0.01). In addition, the relationship between % defect and the number and/or location of coronary artery stenosis in 22 patients with CAD, in whom exercise-induced perfusion defects had completely resolved at redistribution, showed that % defect is a useful indicator for quantitating perfusion abnormalities. In conclusion, the extent of perfusion abnormalities can be expressed in the unit of gram with this method.

[Usefulness of serum cardiac myosin light chain I for the estimation of acute myocardial infarction size].

To evaluate the usefulness of serum level of cardiac myosin light chain I (LC I) for the estimation of the extent of acute myocardial infarction (AMI), peak LC I level was compared with myocardial infarction weight (AMI weight) which was obtained by myocardial emission tomography with Tc-99m pyrophosphate (PYP). In 11 patients with AMI, serum LC I levels were measured once a day in most cases, and plasma CPK levels were measured serially (every 4 hours at least 48 hours after admission). Tc-99m PYP imagings were performed at second or third day of AMI, and AMI weight was calculated from the voxel numbers of myocardial hot spot in which Tc-99m PYP had accumulated. Peak LC I level correlated well with AMI weight (r = 0.72, p less than 0.02). As well as peak LC I level, peak CPK level correlated well with AMI weight (r = 0.68, p less than 0.05). But the estimation of the infarct size from peak LC I level had the following advantages over the estimation from peak CPK level. 1) We could compare peak LC I level with AMI weight in all 11 patients, but peak CPK level was able to compared with AMI weight in only 9 of them. This was because CPK level changed rapidly and reached maximum within 24 hours after the onset of AMI, while LC I level peaked after 3 to 5 days. 2) A good correlation between LC I and AMI weight was obtained by the determination of serum LC I level once a day.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical implications of diffuse slow washout of thallium-201 in exercise stress myocardial SPECT].

Clinical implications of diffuse slow washout of thallium-201 (DSWO) in exercise-redistribution myocardial SPECT were studied. Thallium-201 washout rate was calculated by Bull's-eye method. DSWO was defined as having abnormal thallium-201 washout rate (less than 30% per 3 hours) in more than two thirds of each coronary artery (CA) area. OF 974 patients whose exercise heart rate exceeded 120/min, 51 (5.2%) showed DSWO and coronary angiography was performed in 43. Twenty-three patients (53%) showed triple vessel disease (3VD), 8 (19%) showed single or double vessel disease (1VD/2VD) and 12 (28%) showed normal CA. Patients with normal CA consisted of 6 patients with hypertrophic cardiomyopathy (HCM), 5 with hypertension (HT) and one with electrocardiographic abnormality only. The causes of DSWO were assessed from the history of effort angina (EA) and congestive heart failure (CHF), delayed fill-in of the perfusion defect and the ratio of lung to heart thallium-201 activity (L/M) at exercise as an indicator of the left ventricular (LV) function. High prevalence of EA (74%), high incidence of scintigraphic delayed fill-in (83%) and normal L/M suggested diffuse LV ischemia as the cause of DSWO in 3VD. On the other hand in patients with 1VD/2VD, LV dysfunction at exercise was considered as the cause of DSWO because of low prevalence of EA (13%) and scintigraphic delayed fill-in (13%) (p less than 0.01, p less than 0.005 each vs 3VD), and high L/M (p less than 0.001 vs 3VD) and high prevalence of CHF (38%, NS).(ABSTRACT TRUNCATED AT 250 WORDS)

[Myocardial perfusion abnormality and chest pain in patients with hypertrophic cardiomyopathy].

To investigate the role of myocardial ischemia in the development of chest pain in patients with hypertrophic cardiomyopathy (HCM), exercise stress (Ex) redistribution myocardial single photon emission CT's (SPECT's) with thallium-201 (Tl) were obtained in 27 patients with HCM. In all patients, coronary arteries were normal arteriographically. Patients were classified into NYHA Class I, II and III according to the frequency and severity of the chest pain during daily life. In these 3 groups, age, sex and intraventricular septal thickness measured by echocardiography were not different. Types of myocardial perfusion obtained by myocardial SPECT's were divided into 5: 1) normal perfusion, 2) no perfusion defect with abnormal myocardial Tl washout rate (WOR) during 3 hours (less than 30%) [Def(-)/WORabn], 3) reversible perfusion defect (RD), 4) fixed defect with abnormal WOR (FD/WORabn), 5) fixed defect with normal WOR (FD/WORnl). In 14 patients with Class I, 9 patients (64%) showed normal perfusion but the rest showed perfusion abnormality (def(-)/WORabn in 3 and RD in 2). In Class II and III, all patients showed perfusion abnormalities of RD, FD/WORabn or FD/WORnl. As the functional class progressed from Class II to III, the ratio of fixed defect (both WORnl and WORabn) to RD increased, but it was not statistically significant. In 2 patients in whom Ex SPECT's were repeated because of the progression of the chest pain, the severity of the perfusion abnormality also progressed. Perfusion abnormalities were observed most frequently in anterior (35%), then inferior/posterior (20%) and septal wall (18%).(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of left ventricular function by gated cardiac blood-pool emission computed tomography using a rotating gamma camera].

To elucidate the usefulness of gated cardiac blood-pool single photon emission CT (SPECT) with Tc-99m for the evaluation of left ventricular (LV) global and regional functions, 18 patients with coronary artery disease were studied. Thirty-two gated projection images were obtained over 360-degree at 16 frames per cardiac cycle. As LV volume was calculated by integrating the numbers of voxels which constituted LV and multiplying by the volume of a single voxel (0.1143 ml), we performed phantom studies to determine the appropriate cut-off level to detect LV outline. These cut-off levels were affected by the background activity and organ volume itself. So we constructed Volume-Cut-Level-Curve at each background activity. In clinical studies, short axis images which constituted LV were selected and provisional LV volumes were calculated at the cut-off levels of 45, 50 and 55%. These volumes were plotted on the Volume-Cut-Level-Curve and the true cut-off levels were obtained to calculate LV end-diastolic or end-systolic volume (EDV, ESV). The cut-off levels were different at every patient and ED or ES. EDV, ESV and LV ejection fraction obtained by SPECT were correlated well with those obtained by contrast ventriculography (LVG) (r = 0.89, 0.94, 0.94 each, p less than 0.01). For the LV wall motion analysis, LVGs obtained at two projections were compared with SPECT or gated cardiac blood-pool planar imaging (Planar) in 5 segments. In addition to visual comparison, wall motion scores (WMS) based on the degree of wall motion abnormality were calculated in each segment. Correlation of WMS between LVG and SPECT (r = 0.84) was significantly (p less than 0.01) superior to that between LVG and Planar (r = 0.62). Especially in SPECT, wall motion analyses at septal and infero-posterior segments were superior to those in Planar. Although gated SPECT requires relatively long time to perform, it is a useful method to detect LV global and regional functions.