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Biomedical subjects

H Kambara

Publications and source records attributed to H Kambara.

At least 109 records · Page 6Linked to original sources
PubMed1987

Early estimation of acute myocardial infarct size soon after coronary reperfusion using emission computed tomography with technetium-99m pyrophosphate.

Early appearance of positive findings on a technetium-99m pyrophosphate scan has been shown to be associated with the presence of a reperfused acute myocardial infarction (AMI). Early technetium-99m pyrophosphate imaging was performed by emission computed tomography to evaluate reperfusion and to test the feasibility of estimating infarct size soon after coronary reperfusion based on acute positive tomographic findings. Twenty-seven patients with transmural AMI who were treated with intracoronary urokinase infusion followed by percutaneous transluminal coronary angioplasty underwent pyrophosphate imaging 8.7 +/- 2.1 hours after the onset of AMI. None of the 8 patients in whom reperfusion was unsuccessful had acute positive findings. Of 19 patients in whom reperfusion was successful, 17 had acute positive findings (p less than 0.001). In these 17, tomographic infarct volumes were determined from reconstructed transaxial images. The threshold for areas of increased pyrophosphate uptake within the infarct was set at 60% of peak activity by the computerized edge-detection algorithm. The total number of pixels in all transaxial sections showing increased tracer uptake were added and multiplied by a size factor and 1.05 g/cm3 muscle to determine infarct volume. The correlations of tomographic infarct volumes with peak serum creatine kinase (CK) levels (r = 0.82) and with cumulative release of CK-MB isoenzyme (r = 0.89) were good. Moreover, the time to positive imaging was significantly shorter than that to peak CK level (8.5 +/- 2.3 vs 10.4 +/- 2.2 hours, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Interventricular septal motion in acute myocardial infarction with proximal and distal left anterior descending coronary lesions.

To evaluate the ability of echocardiography to detect and localize lesions of the proximal and distal left anterior descending (LAD) coronary arteries, the systolic excursion of the left side of the septum and the ratio of septal to posterior wall excursion (IVS/PW) were measured in 26 patients with acute myocardial infarction (AMI) and nine normal control subjects. The patients with proximal LAD lesions had septal wall excursions of less than 3 mm, whereas in those with distal LAD lesions septal wall excursions were more than 3 mm. All patients with proximal LAD lesions showed an IVS/PW ratio of less than 0.4, but in those with distal LAD lesions the ratio was 0.4 or greater. We conclude that reduced or absent interventricular septal motion in anterior AMI suggests an LAD lesion, and a septal excursion of less than 3 mm suggests involvement of the proximal LAD artery, whereas septal excursion of 3 mm or more indicates involvement of the distal LAD artery.

Adult↗
PubMed1987

Detection of coronary artery disease with 13N-ammonia and high-resolution positron-emission computed tomography.

In order to evaluate the detectability of coronary artery disease (CAD) with positron-emission computed tomography (PET), we performed 13N-ammonia myocardial PET scanning at rest and with exercise loading in 20 normal subjects and 40 patients with CAD, by means of a high-resolution, multi-slice, whole-body PET scanner. Myocardial PET scanning was performed 3 minutes after injection of 13N-ammonia at rest and during exercise. The circumferential profile analysis of resting PET images revealed regional hypoperfusion in 96% of CAD patients with previous myocardial infarction and in 29% of those without infarction. Exercise PET studies showed high sensitivity (93%) in detecting CAD without myocardial infarction, whereas no abnormal hypoperfusion was detected in normal subjects. Segmental analysis of regional myocardial perfusion with exercise stress identified 67 of 75 stenosed vessels (89%). We conclude that 13N-ammonia myocardial PET with exercise loading provides high-quality tomographic images of regional myocardial perfusion and is a valuable technique for detecting CAD.

Adult↗
PubMed1987

Randomized double-blind trial of intracoronary urokinase for acute myocardial infarction: multicenter study.

The efficacy of intracoronary urokinase (UK) in an acute myocardial infarction has not been firmly established in a randomized fashion. Two hundred and ten patients were randomized to UK therapy (107 patients) and placebo (103 patients). Successful recanalization was achieved in 74% of the UK group vs 17% in the placebo group (p less than 0.01). The success rate was dose dependent up to 960,000 I.U. Clinical course was favorable and left ventricular enddiastolic pressure was reduced significantly in the UK group compared with the placebo group (p less than 0.05). Ejection fraction one month after the study was better in the reopened group than in the occluded group. Thus, early administration of UK can establish coronary reflow in a high proportion of patients and appears to favor the clinical course.

Aged↗
PubMed1987

Beneficial effects of nicorandil on cardiovascular hemodynamics and left ventricular function.

The effects of sublingual nicorandil (5 mg), an antianginal drug, were investigated in pacing-induced ischemia in 11 patients with coronary artery disease. Hemodynamic parameters were measured, and single-plane left ventriculograms were obtained in control and postpacing periods both before and after pretreatment with nicorandil. Regional wall motion of the left ventricle was assessed by measuring shortening of the radial axes originating from the center of the gravity of the end-diastolic silhouette. Heart rate, left ventricular (LV) systolic pressure, and end-diastolic volume index were not changed in immediate postpacing with or without medication. The LV end-diastolic pressure decreased from 22.0 +/- 1.8 (SEM) to 18.4 +/- 1.7 mm Hg (p less than 0.01) and LV systolic volume index from 48.5 +/- 7.1 to 37.4 +/- 7.7 ml/m2 (p less than 0.01). Ejection fraction increased from 42.2 +/- 3.7 to 56.7 +/- 3.7% (p less than 0.01), stroke index (SI) from 34.5 +/- 3.7 to 43.1 +/- 2.2 ml/beat/m2 (p less than 0.01), and cardiac index (calculated from heart rate and SI) from 2.49 +/- 0.30 to 3.09 +/- 0.19 L/min/m2 (p less than 0.01). With rapid right ventricular pacing, dyskinesis of the left ventricle increased in both area and degree, but was improved with premedication with nicorandil. Thus, nicorandil has salutary effects on ventricular contractile and hemodynamic responses to transient ischemia induced by pacing stress.

Angina Pectoris↗
PubMed1987

[Evaluation of coronary reperfusion for acute myocardial infarction by emission CT using technetium-99m pyrophosphate].

Twelve patients with acute transmural myocardial infarction (AMI) were treated with percutaneous transluminal coronary angioplasty (PTCA) following intracoronary thrombolysis using urokinase, and underwent technetium-99m stannous pyrophosphate (Tc-99m-PPi) imaging 9.2 +/- 2.1 hours after the onset of chest pain. The imaging was performed with emission computed tomography (ECT). Compared to planar imaging, this allowed more accurate detection of small myocardial infarcts and accurate measurements of infarcts irrespective of their location was also made. Early Tc-99m-PPi images were obtained to test the hypothesis that an early, abnormal Tc-99m-PPi image suggest successful reperfusion. The results were presented for two groups of patients: three with unsuccessful reperfusion (Group A) and nine with successful reperfusion (Group B). Eight of the nine patients with successful reperfusion had positive acute Tc-99m-PPi images. On the contrary, all the three patients for whom reperfusion failed had negative acute Tc-99m-PPi images. We also examined the feasibility of estimating infarct size using positive Tc-99m-PPi images in patients with successful reperfusion during the early phase of AMI. The Tc-99m-PPi uptake score (Tc-US) was used to measure infarct size in this study. Areas of increased Tc-99m-PPi uptake within myocardial infarcts were threshold at 60% of the peak activity. The Tc-US of each patient was obtained to sum the scores of all myocardial segments using a scoring system with a maximum score of 108. Using this method, Tc-US ranged from 2 to 39. The correlation of Tc-US with the peak serum creatine kinase level was significant (r = 0.91).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Exercise 13NH3-positron emission computed tomography (PET) versus exercise single photon emission computed tomography (SPECT)].

The value of exercise positron emission computed tomography (PET) was determined by comparing it with exercise T1-201 single photon emission computed tomography (SPECT) using graded ergometer exercise in 10 anginal patients with left anterior descending coronary (LAD) involvement (stenosis greater than or equal to 75%) with or without other coronary stenosis. The distribution of N-13 ammonia or T1-201 was determined and expressed as percent count ot the highest count on the circumferential profile curve (CPC) in the transaxial image. Two standard deviations below the mean counts of six normal hearts for PET and ten for SPECT were considered as the lower limit of normal, and these were determined separately during exercise and at rest. The ischemic areas per total myocardial areas (%C), the accuracy in diagnosing coronary involvement and the identification of coronary branch involvement were determined by CPC analysis in three corresponding slices. Regional analyses revealed that accuracy in diagnosing proximal left anterior descending artery (LAD) involvement was higher with PET (9/10) than with SPECT (7/10), but the difference was not statistically significant. The accuracy in diagnosing right coronary or circumflex artery stenosis was 9/10 with PET and 8/10 with SPECT (NS); the %C was significantly higher with PET than with SPECT during exercise (PET: mean +/- SD = 56 +/- 21%, SPECT: 35 +/- 21%, p less than .01) in spite of smaller double products (x10(3] (PET: 18.9 +/- 4.7, SPECT: 23.5 +/- 5.7, p less than .02). Thus, exercise PET was more reliable in evaluating regional ischemia and in semiquantifying the ischemic area in the myocardium.

Ammonia↗
PubMed1987

[Colored spatial mapping electrocardiography for detecting myocardial infarction].

Colored spatial mapping electrocardiography (ECG) was developed for practical use from Frank lead vectorcardiography using a microcomputer system (CERX-CQ3001). Compared to body surface electrocardiography this new device facilitated easy recording and analysis for display on eight-colored spatial mapping electrocardiography at points equivalent to those on a terrestrial globe at intervals of 20 degrees longitude and 10 degrees latitude. In this study, the extent and direction of the Q waves were easily recognized with the aid of a colored display and mapping electrocardiography. To quantitatively evaluate infarct size, the total Q wave area (sigma Aq) was calculated from the mapping electrocardiograms of 12 patients with anteroseptal myocardial infarction, and compared with thallium defect scores obtained by single photon emission CT (SPECT) and the left ventricular ejection fraction (EF). Defect scores were calculated using short-axis images. Sigma Aq was correlated with defect scores and EF (r = 0.83, 0.45, respectively). This new type of colored spatial mapping electrocardiography proved useful for detecting myocardial infarction and for evaluating infarct size.

Color↗
PubMed1986

Detection and evaluation of tricuspid regurgitation using a real-time, two-dimensional, color-coded, Doppler flow imaging system: comparison with contrast two-dimensional echocardiography and right ventriculography.

To detect and evaluate regurgitant flow in tricuspid regurgitation (TR) with a newly developed, realtime, 2-dimensional (2-D), color-coded, Doppler flow imaging system (Doppler 2-D echo), 27 patients (18 with suspected TR and 9 normal subjects) were examined and the findings were compared with those obtained using contrast 2-D echocardiography (contrast 2-D echo) and right ventriculography. In 16 of 18 patients with suspected TR, Doppler 2-D echo easily visualized the color-coded regurgitant flow in the right atrium and estimated the severity of TR from the distance of the visible TR jet. On the basis of the QRS synchronized appearance of contrast in the inferior vena cava by the subxiphoid approach or of the negative contrast effect above the tricuspid valve just after the contrast entered the right ventricle with its subsequent back-and-forth movements across the tricuspid valve, Doppler 2-D echo was more sensitive and specific in detecting TR (100% and 100%) than contrast 2-D echo (75% and 82% in the subxiphoid view, 56% and 100% in the 4-chamber view) when the fast Fourier transformation frequency analysis was used as the standard of TR, and it was more sensitive in detecting TR (85%) than contrast 2-D echo (69% in the subxiphoid approach, 46% in the 4-chamber view) when right ventriculography was used as the standard of TR. Additionally, the severity of TR as shown by Doppler 2-D echo correlated fairly well with that shown by right ventriculography. Thus, Doppler 2-D echo is clinically useful for detecting and evaluating TR.

Adult↗
PubMed1986

Asynchronous filling in ischemic heart disease and hypertrophic cardiomyopathy.

A multigated blood-pool study was performed to assess regional and global emptying and filling in 16 patients with hypertrophic cardiomyopathy (HCM), 43 patients with ischemic heart disease (IHD), and 14 controls. The regional volume curve was fitted using second-order harmonics in the Fourier series, while the global left-ventricular volume curve was fitted using third-order harmonics. As asynchronous indices, the standard deviations (SD) in distribution histograms of time to end-systole (TES), time to peak ejection (TPE), and time to peak filling (TPF) were obtained in the left ventricle. In patients with IHD, the TPF-SD was higher (14.4 +/- 11.3 degrees) than the TES-SD (7.8 +/- 5.1 degrees) and TPE-SD (8.1 +/- 5.9 degrees), suggesting the presence of asynchronous filling. In patients with HCM, the TPF-SD was also higher (11.6 +/- 11.1 degrees) than the TES-SD (3.5 +/- 2.4 degrees) and TPE-SD (6.2 +/- 4.4 degrees). The phase delay was localized in the anteroseptal or apical region in all 5 HCM patients with abnormal wall motion, while it corresponded with the region of abnormal wall motion in the patients with IHD. The TPF-SD was inversely correlated with the left-ventricular ejection fraction (r = -0.46), peak filling rate (r = -0.50), and the ratio of peak filling rate to peak ejection rate (r = -0.52), suggesting that asynchronous filling is related to global diastolic disturbance. We conclude that asynchronous filling is often present in patients with IHD and HCM, and that our technique can be used to obtain a quantitative assessment of regional asynchronous emptying and filling in these diseases.

Adult↗
PubMed1986

Quantification of thallium-201 myocardial uptake using serial dynamic imaging at rest and during exercise.

The thallium-201 myocardial uptake ratio was measured using serial dynamic imaging of the initial uptake phase following an intravenous bolus injection. It revealed no significant difference at rest between non-coronary heart disease and coronary artery disease, while it was greater in cases with left ventricular hypertrophy. With exercise loading, this value significantly increased in non-coronary heart disease, whereas less increase was observed in coronary artery disease. This increasing capability was lower in multivessel disease compared with single-vessel disease.

Adult↗
PubMed1986

Interpolating scan and oblique-angle tomograms in myocardial PET using nitrogen-13 ammonia.

The effect of low sensitivity areas or gaps between adjacent slices of the multislice positron emission tomography on detection of myocardial perfusion abnormality with 13NH3 was evaluated segmentally in 36 patients with coronary artery disease at rest or during exercise. The detectability of the defects in RCA or LAD region was 80% in single-position scans in stress studies. The false-negative defects were located mainly in the inferior wall, apicoinferior wall, or high anterior wall. When the patients were moved half the slice interval to perform the interpolating scan, and the two sets of images were interlaced with each other, the detectability increased to 88%. The interpolating scan also allowed reconstruction of long-axis and short-axis tomograms in high quality, which further improved the detectability of perfusion defects (100% for RCA or LAD and 75% for LCX lesion) and helped in understanding the anatomic relationships to the coronary artery territories.

Ammonia↗