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Biomedical subjects

H Kambara

Publications and source records attributed to H Kambara.

At least 127 records · Page 7Linked to original sources
PubMed1986

[201Tl myocardial scintigraphy and 13N-NH3 positron computed tomography in evaluating myocardial blood flow].

The early distribution of thallium-201 (Tl-201) is related to blood flow within the limits of the physiological range. We examined the ratio of myocardial uptake of Tl-201 to the total dose administered at rest and during exercise, in order to assess myocardial blood flow. The usual dose of Tl-201 (2-3 mCi) was diluted to 20 ml of normal saline and 15 ml were injected intravenously as a bolus. Subsequently the remaining 5 ml were injected in the same manner. Myocardial Tl-201 uptakes after the first dose were comparable to those of the second dose at rest when myocardial uptake immediately before the second injection was subtracted and multiplied by 3 (r = 0.98). This technique was applied during exercise to evaluate coronary reserve. Symptom-limited exercise was performed using a sitting ergometer and the first dose of Tl-201 was administered. After the routine scintigraphy with multiple views was completed, a second dose was given at rest. Myocardial uptake was greater during exercise than at rest by 32.6 +/- 15.1% (mean +/- SD) in 18 normal subjects. This was significantly greater than that of 20 patients with coronary artery disease (5.8 +/- 15.3%; p less than 0.005). Tl-201 scintigraphy has inherent limitations as to its quantitation, while positron scintigraphy using 13N-NH3 has some advantages for calculations. Percent myocardial uptake of 13N during exercise was practically equal to that at rest in six normal subjects (97.1 +/- 25.0%), but it was slightly reduced in patients with coronary artery disease (90.1 +/- 18.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Circulation↗
PubMed1986

[Asynchronous wall motion in patients with ischemic heart disease assessed by higher-order harmonics of the Fourier series].

To assess regional cardiac function in patients with ischemic heart disease (IHD), multigated blood-pool studies using higher-order harmonics of the Fourier series were performed for 14 normal persons and 37 patients with IHD. IHD was further divided into IHD (I) (EF greater than or equal to 50%) and IHD (II) (EF less than 50%). A pixel-by-pixel volume curve was simulated using second order harmonics of the Fourier series to create functional images of the following parameters: time to endosystole (TES), peak ejection rate (PER), time to PER (TPE), peak filling rate (PFR), and time to PFR (TPF). TES (SD), TPE (SD), and TPF (SD) were calculated as the standard deviations of left ventricular (LV) histograms of each phase, representing indexes of asynchronous wall motion. An LV volume curve was simulated using third order harmonics to calculate PFR, PFR/PER, and TPF/TPE, representing indexes of diastolic function. TES (SD) was abnormal in 10 cases (50%), and TPE (SD) was abnormal in seven cases (35%) of IHD (II). On the contrary, TPF (SD) was abnormal in three cases (18%) of IHD (I) and 15 cases (75%) of IHD (II), indicating that diastolic asynchronous indexes are more sensitive than systolic asynchronous indexes in detecting IHD. IHD (I) and IHD (II) showed lower PFR (2.32 +/- 0.55, 1.64 +/- 0.46 EDV/sec) and lower PFR/PER (0.84 +/- 0.15, 0.68 +/- 0.26) than those in normals (3.25 +/- 0.98 EDV/sec, 0.99 +/- 0.19), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Volume↗
PubMed1985

Detection of intracardiac shunt flow in atrial septal defect using a real-time two-dimensional color-coded Doppler flow imaging system and comparison with contrast two-dimensional echocardiography.

To evaluate the noninvasive detection of shunt flow using a newly developed real-time 2-dimensional color-coded Doppler flow imaging system (D-2DE), 20 patients were examined, including 10 with secundum atrial septal defect (ASD) and 10 control subjects. These results were compared with contrast 2-dimensional echocardiography (C-2DE). Doppler 2DE displayed the blood flow toward the transducer as red and the blood flow away from the transducer as blue in 8 shades, each shade adding green according to the degree of variance in Doppler frequency. In the patients with ASD, D-2DE clearly visualized left-to-right shunt flow in 7 of 10 patients. In 5 of these 7 patients, C-2DE showed a negative contrast effect in the same area of the right atrium. Thus, D-2DE increased the sensitivity over C-2DE for detecting left-to-right shunt flow (from 50% to 70%). However, the specificity was slightly less in D-2DE (90%) than C-2DE (100%). Doppler 2DE could not visualize right-to-left shunt flow in all patients with ASD, though C-2DE showed a positive contrast effect in the left-sided heart in 9 of 10 patients with ASD. Thus, D-2DE is clinically useful for detecting left-to-right shunt flow in patients with ASD.

Adolescent↗
PubMed1985

Septal Q wave in exercise testing: evaluation by single-photon emission computed tomography.

Changes of septal Q waves in lead V5 by exercise were evaluated with single-photon emission computed tomography. Coronary artery disease was present in 66 patients, 48 of whom had left anterior descending coronary artery (LAD) involvement. Forty-one subjects had normal coronary arteries. All patients under investigation were classified into 3 groups: group A (18 patients)--regression of Q amplitude during exercise; group B (48 patients)--progression or no change of Q wave or a new Q wave during exercise; and group C (41 patients)--no Q waves at rest and during exercise. Perfusion defects of the septum were calculated 3-dimensionally and expressed as a percent of the total septum. Seventeen patients (94%) in group A showed septal perfusion defects by exercise and all of them had LAD stenosis. Forty-three patients (90%) in group B showed no septal perfusion defects, but the others with perfusion defects had LAD stenosis. In group C, 23 of 41 patients (56%) had an LAD lesion, of whom 91% showed septal perfusion defects; none of the remaining 18 patients without LAD stenosis showed perfusion defects. The area of septal perfusion defects during exercise was larger in group A (62 +/- 19%) and in group C (52 +/- 19%) than in group B (23 +/- 9%) (groups A vs B, p less than 0.001; groups C vs B, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Circulation↗
PubMed1985

Coronary thrombolysis with urokinase infusion in acute myocardial infarction: multicenter study in Japan.

The efficacy of intracoronary administration of urokinase was evaluated in 514 patients with acute myocardial infarction (anterior, 296 patients; inferior, 195; lateral or posterior, 18; and anterior and inferior, five). The time between onset of chest pain and coronary arteriography was 0.5 to 81.0 hr with an average of 5.0 hr. Initial administration of nitrates resulted in recanalization of the coronaries in 9.3%. Subsequently, urokinase was infused into the coronary arteries, and coronary thrombolysis was successfully achieved in 66.8%. The success rate was low in a group with average infusion speed of more than 30,000 units/min or with a total dose of urokinase of 480,000 units or less. Complications, mainly arrhythmias, were present in 111 patients (33.2%) of the 334 who had successful thrombolysis and in 18 patients (10.8%) of the 166 with unsuccessful thrombolysis, but serious hemorrhage was rare and no fatal case was reported. Patients who had successful thrombolysis had less in-hospital mortality than those who did not (6.3 vs 13.3%). Thus, coronary thrombolysis can be achieved effectively and relatively safely with a sufficient amount of intracoronary urokinase administration in acute myocardial infarction.

Adult↗
PubMed1985

Myocardial positron computed tomography with 13N-ammonia at rest and during exercise.

To assess the value of myocardial-perfusion positron computed tomography (PCT) for the evaluation of coronary artery disease (CAD), 13N-ammonia PCT using a whole-body multislice PCT device was performed at rest and during exercise in 6 normal subjects and 19 patients with angiographically documented CAD. The 13N-ammonia distribution in the myocardium was assessed both qualitatively and quantitatively. At rest and during exercise, the tracer distribution was homogeneous in the 6 normal cases. In the 19 patients with CAD, regional hypoperfusion was observed in 14 cases (74%) at rest and in 18 cases (95%) during exercise. Additional perfusion abnormalities were detecting during exercise in 12 cases. Segmental analysis of the myocardial perfusion identified 30 out of 34 stenosed vessels (88%) during exercise, with only one false-positive finding of diseased vessels (specificity, 98%). For the quantitative analysis of myocardial perfusion by PCT, the percentage of change in the tracer concentration in the same region between the rest and stress images was calculated. The concentration was slightly increased in normal myocardial segments (14.4% +/- 5.8%; P less than 0.001), whereas in CAD, it was significantly decreased in segments with stenosed vessels (-18.0% +/- 18.3%; P less than 0.02). We conclude that 13N-ammonia PCT at rest and during exercise provides high-quality images, and is a sensitive and effective technique for detecting CAD and identifying individual stenosed vessels. Furthermore, this technique makes possible quantitative assessment of the coronary reserve function.

Adult↗
PubMed1985

Thallium-201 myocardial perfusion imaging in myocarditis.

TI-201 myocardial perfusion imaging was performed in six patients with clinically documented myocarditis. Each case manifested electrocardiographic abnormalities with elevation of serum cardiac enzymes and no significant stenosis of the coronary arteries observed on angiogram. Resting TI-201 images were visually assessed by three observers. Focal perfusion defects were observed in three cases (50%), among which two showed multiple perfusion defects. Emission computed tomography using TI-201 clearly delineated multifocal lesions in the first case. On the other hand, no significant perfusion defects were noted in the remaining three cases. Thus, myocarditis should be considered as one of the disease entities that may produce perfusion defects on TI-201 myocardial imaging.

Adolescent↗
PubMed1985

Effects of intracoronary thrombolysis on infarct size and left ventricular function in patients with anterior myocardial infarction--enzymatic, electrocardiographic, radionuclide and hemodynamic evaluations.

The influence of the duration of ischemia on infarct size and left ventricular function (LV) was assessed in 30 patients with a first anterior myocardial infarction (MI) and intracoronary thrombolysis (ICTL) on admission. The occlusion time of the left anterior descending coronary artery (LAD) was 4 hours or less in 11 patients (group I), 4-10 hours in 11 (group II) and 10 hours or more in eight (group III). Serial measurements of serum creatine kinase-MB were carried out during the acute phase. Four weeks after the procedure, electrocardiographic pathological Q waves on 34-lead precordial mapping were scored, viable left ventricular myocardial volume and the ratio of infarcted to total left ventricular myocardial volume was estimated by myocardial emission computed tomography (ECT) with thallium-201. In the acute phase enzymatic estimation of infarct size showed a significant difference between group I and the other two groups but not between groups II and III; there were no significant differences in the degree of left ventricular asynergy among the three groups. In the chronic phase infarct sizes evaluated by both Q wave mapping and ECT were smaller in group I than those in group II, which were smaller than those in group III; there were significant differences in the degree of LV asynergy among the three groups (group I less than II less than III). LV function was nearly normal in group I, moderately impaired in group II, but severely depressed in group III 4 weeks later. The present study indicates that infarct size extends and LV function deteriorates with the duration of occlusion of the LAD and that not only early (less than or equal to 4 hours) but also later (4-10 hours) reperfusion is beneficial to prevent the extension of MI and deterioration of LV function in patients with anterior MI.

Adult↗
PubMed1985

Left ventricular responses to supine bicycle exercise assessed by radionuclide angiocardiography and a Swan-Ganz catheter.

Left ventricular responses to supine bicycle ergometer exercise were studied by gated radionuclide angiocardiography (RNA), in 12 normal subjects (group A), 11 coronary patients without effort angina (group B) and 17 coronary patients with effort angina (group C). In the serial measurement of global ejection fraction (EF) there was a significant increase during peak exercise (PEx) in group A and B. In group C, global EF during mild exercise (MEx) did not increase, but decreased significantly during PEx. These results suggest the necessity of achieving adequate exercise loading in the diagnosis of exercise-induced ischemia, and also, that the serial measurement of global EF during exercise appears to be highly valuable. In the assessment of regional wall motion on the basis of regional EF, abnormal responses to exercise were highly inducible in the anteroseptal region in coronary patients with left anterior descending artery involvement. Abnormal wall motion in the other regions was less indicative for right coronary or left circumflex artery dysfunction. We examined hemodynamic responses to exercise by a Swan-Ganz catheter during RNA study in 5 patients of group A, 5 of group B, and 9 of group C. There was a large increase in left ventricular stroke work index (LVSWI) with a small rise in pulmonary capillary wedge pressure (PCWP) in group A. In group B LVSWI increased with a moderate rise in PCWP during PEx. In group C there was a negligible increase of LVSWI despite a marked rise in PCWP. A similar relationship was present between the LVSWI and the end-diastolic count (EDC) in the left ventricular region of interest. In MEx, however, the rise in PCWP in group C was more prominent than the increase in EDC. Thus, the present data indicate that the left ventricle in group C operates on a steeper portion of the diastolic pressure-volume curve than that in group A or B.

Adult↗
PubMed1985

Dynamic positron computed tomography of the heart with a high sensitivity positron camera and nitrogen-13 ammonia.

Dynamic positron computed tomography (PCT) of the heart was performed with a high-sensitivity, whole-body multislice PCT device and [13N]ammonia. Serial 15-sec dynamic study immediately after i.v. [13N]ammonia injection showed blood pool of the ventricular cavities in the first scan and myocardial images from the third scan in normal cases (n = 4). In patients with myocardial infarction (n = 8) and mitral valve disease (n = 2), tracer washout from the lung and myocardial peak time tended to be longer, suggesting presence of pulmonary congestion. PCT delineated tracer retention in the dorsal part of the lung. Serial 5-min late dynamic study in nine cases showed gradual increase in myocardial activity for 30 min in all normal segments and 42% of infarct segments, while less than 13% activity increase was observed in 50% of infarct segments. Thus, serial dynamic PCT with [13N]ammonia assessing tracer kinetics in the heart and lung is a valuable adjunct to the static myocardial perfusion imaging for evaluation of various cardiac disorders.

Ammonia↗
PubMed1985

[Evaluation of myocardial viability in myocardial infarction by thallium-201 emission computed tomography].

Stress thallium-201 emission computed tomography (ECT) was performed for 24 patients with myocardial infarction for quantitative evaluation of regional thallium redistribution and washout. ECT was performed using a rotating gamma camera 10 minutes and 2.5 hours after thallium injection during maximal exercise. Three short-axis sections and one central long-axis section were selected for the circumferential profile curves. Redistribution (%) and washout (%) were calculated from the stress and redistribution profile curves in each section. These parameters were evaluated by comparison with regional wall motion on radiographic contrast ventriculography. Forty-eight of the 52 segments (92%) with normal thallium uptake showed normal wall motion. Among the segments with abnormal thallium uptake, normal or hypokinetic wall motion was observed in 12 of 13 segments (92%) with more than 20% redistribution and in 16 of 19 segments (84%) with 10-20% redistribution, while it was observed in only 15 of 36 segments (42%) without redistribution (p less than 0.001). Among 48 infarcted segments, 16 segments (33%) showed significant redistribution on ECT analysis. Normal or hypokinetic wall motion was observed in three of five segments (60%) with more than 20% redistribution, and in 10 of 11 segments (91%) with 10-20% redistribution, while it was seen in only eight of 30 segments (17%) without redistribution (p less than 0.005).

Heart↗
PubMed1985

[Myocardial positron computed tomography using N-13 ammonia for evaluating coronary artery disease: comparison with thallium-201 emission computed tomography].

To assess myocardial perfusion in patients with coronary artery disease (CAD), N-13 ammonia positron computed tomography (PCT) was performed for 32 cases, and the PCT images were compared with those of single-photon emission computed tomography (SPECT) using thallium-201. Myocardial perfusion images were obtained with a whole-body multislice PCT device following the intravenous injection of 10 to 20 mCi N-13 ammonia at rest (32 cases) and during exercise (23 cases). Eleven cases underwent serial 15-20 second dynamic studies immediately following the N-13 ammonia injection. Serial dynamic study showed the blood-pool images in the first scan, and enabled assessment of tracer washout from the blood-pool, and the lung as well as washin into the myocardium. PCT provided clear resting myocardial perfusion images in all cases. PCT images were of higher quality than those of SPECT due to higher spatial resolution with less statistical noise, allowing delineation of the right ventricular myocardium and papillary muscles in many cases. Both PCT and SPECT detected perfusion abnormalities in 18 of the 19 cases with myocardial infarction, without false positive findings. PCT yielded stress myocardial images and permitted comparative evaluations of myocardial perfusions at rest and during exercise in all 23 cases. Perfusion abnormalities were detected in 14 cases (74%) at rest and in 18 cases (95%) during exercise among 19 patients with CAD. No false positives were observed, either by resting or stress PCT imaging. Stress myocardial PCT identified regional perfusion abnormalities in 30 of the 34 regions supplied by stenosed vessels (88%). High resolution PCT images enabled precise evaluation of myocardial perfusions which proved valuable for assessing myocardial perfusions before and after aorto-coronary bypass surgery. The present study proved advantages of N-13 ammonia PCT in creating three-dimensional high resolution images of the myocardium, which facilitates precise evaluation of myocardial perfusions. Furthermore, its potential capabilities in quantifying coronary reserve function will be very useful. This method should provide valuable pathophysiological information for CAD, as well as for metabolic PCT imaging.

Ammonia↗