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Biomedical subjects

S L Bacharach

Publications and source records attributed to S L Bacharach.

At least 55 records · Page 3Linked to original sources
PubMed1992

Regional left ventricular wall thickening. Relation to regional uptake of 18fluorodeoxyglucose and 201Tl in patients with chronic coronary artery disease and left ventricular dysfunction.

BACKGROUND: In previous studies comparing regional 201Tl (201Tl) and 18fluorodeoxyglucose (FDG) activity in patients with chronic coronary artery disease and left ventricular dysfunction, we hypothesized that regions with mild-to-moderate reduction in FDG activity and regions with mild-to-moderate irreversible 201Tl defects after 3- to 4-hour redistribution represent viable myocardium. In the present study, regional FDG and 201Tl activities were compared with regional systolic wall thickening by gated magnetic resonance imaging (MRI) to confirm the presence of viable myocardium in these territories. METHODS AND RESULTS: Twenty-five patients with chronic stable coronary artery disease and left ventricular dysfunction (ejection fraction, 28 +/- 10) underwent exercise 201Tl tomographic imaging (SPECT), using a reinjection protocol, positron emission tomography (PET) with FDG and H2(15)O, and gated MRI. Matched SPECT, PET, and MRI tomograms were analyzed. From the PET data, 105 regions had matched reduction in FDG and blood flow, of which 69 regions had moderately reduced FDG uptake (50-79% uptake relative to a normal reference region) and 36 had severely reduced FDG uptake (less than 50% of normal activity). Regions with moderately reduced as compared with severely reduced FDG activity had greater end-diastolic wall thickness (9.4 +/- 2.6 versus 8.0 +/- 3.7 mm; p less than 0.05) and regional systolic wall thickening (1.7 +/- 2.7 versus -0.7 +/- 2.1 mm; p less than 0.01). From the SPECT data, 169 irreversible 201Tl defects after 3-4 hour redistribution were identified, of which 70 were mild (greater than 65 to less than 85% of maximal 201Tl activity), 52 were moderate (50-65% of maximal activity), and 47 were severe (less than 50% of maximal activity). Regional systolic wall thickening was greater in regions with normal 201Tl uptake (3.3 +/- 2.3 mm) as compared with all other regions. Regions showing only mild or moderate irreversible defects at redistribution, however, showed wall thickening (2.4 +/- 2.4 and 2.2 +/- 2.5 mm, respectively), which was similar to that observed in regions with reversible 201Tl defects (2.1 +/- 2.2 mm). Only regions with severe irreversible defects at redistribution showed absence of thickening (-0.1 +/- 2.9 mm, p less than 0.01 versus all other groups). After 201Tl reinjection, 12 of 47 (26%) regions with severe irreversible defects showed enhanced 201Tl uptake. The impairment in regional systolic wall thickening was not significantly different between 201Tl defects with and without enhanced 201Tl uptake after reinjection. FDG activity, however, was present in all 12 regions (100%) with enhanced 201Tl uptake after reinjection as compared with only five of 35 (14%) that were unchanged after reinjection (p less than 0.01). CONCLUSIONS: Therefore, preserved wall thickness and systolic wall thickening in regions with moderate reduction in blood flow and FDG activity, and in irreversible 201Tl defects that are only mild-to-moderate, provide additional evidence that such regions represent viable myocardium. Moreover, the finding of metabolic activity and 201Tl uptake in regions with reduced blood flow and absent wall thickening provides clinical evidence of hibernating myocardium in humans.

Adult↗
PubMed1992

Spatially dependent deadtime losses in high count rate cardiac PET.

Cardiac PET scans result in nonhomogeneous distributions of activity within the body, which might lead to great variations in singles rates around the detector ring. Conventional deadtime correction algorithms assume that the singles rates are uniform. This paper investigates singles nonuniformities during several typical cardiac scanning protocols (bolus injections of 15O-water and 82Rb, slow infusion of 18F-FDG and static imaging with FDG) and estimates how such nonuniformities might affect quantitative data. Nonuniformity was observed in all studies and was described by an asymmetry index which increased to 58% during bolus water injection, the most inhomogeneous study. These results are valid for any scanner with a ring diameter of approximately 78 cm and are independent of the amount of activity injected. Deadtime losses depend on the amount of activity and on the scanner type. Nonhomogeneities in singles can be shown to produce spatially dependent deadtime correction factors; for our scanner, these were seen to differ by up to 16% from the mean deadtime correction during bolus water injection. To demonstrate the distortions generated by average deadtime correction, the activity distribution during a clinical cardiac study was simulated using a phantom. A simple local deadtime correction and its implementation on our system are described, and the resulting improvements in both absolute and relative quantitation of the phantom study are shown.

Deoxyglucose↗
PubMed1992

Misalignment between PET transmission and emission scans: its effect on myocardial imaging.

Patient movement between PET scanning sequences can produce misalignment between attenuation and emission scans. Such misalignment introduces errors in the emission image. This study evaluates the severity of these errors and their effect upon quantitation of regional myocardial activity. Myocardial FDG scans from 14 patients were reconstructed with simulated translational, rotational and out-of-plane patient movement. Eight myocardial regions from each patient were examined to determine the effect such misalignment might have on regional myocardial activity. A 2-cm shift between attenuation and emission scans produced up to a 30% change in regional activity. Some regions of the myocardium increased while others decreased for a given magnitude and direction of shift, producing anomalous regional myocardial inhomogeneities in the image. Such changes could easily cause qualitative and quantitative misinterpretations. We present data permitting the reader to assess the magnitude of this effect in his/her own clinical setting.

Cardiomyopathy, Hypertrophic↗
PubMed1991

Comparison of exercise radionuclide angiography with thallium SPECT imaging for detection of significant narrowing of the left circumflex coronary artery.

Although quantitation of exercise thallium tomograms has enhanced the noninvasive diagnosis and localization of coronary artery disease, the detection of stenosis of the left circumflex coronary artery remains suboptimal. Because posterolateral regional wall motion during exercise is well assessed by radionuclide angiography, this study determined whether regional dysfunction of the posterolateral wall during exercise radionuclide angiography is more sensitive in identifying left circumflex disease than thallium perfusion abnormalities assessed by single-photon emission computed tomography (SPECT). One hundred ten consecutive patients with CAD were studied, of whom 70 had a significant stenosis of the left circumflex coronary artery or a major obtuse marginal branch. Both regional function and segmental thallium activity of the posterolateral wall were assessed using visual and quantitative analysis. Left ventricular regional function was assessed objectively by dividing the left ventricular region of interest into 20 sectors; the 8 sectors corresponding to the posterolateral free wall were used to assess function in the left circumflex artery distribution. Similarly, using circumferential profile analysis of short-axis thallium tomograms, left ventricular myocardial activity was subdivided into 64 sectors; the 16 sectors corresponding to the posterolateral region were used to assess thallium perfusion abnormalities in the left circumflex artery territory. Qualitative posterolateral wall motion analysis detected 76% of patients with left circumflex coronary artery stenosis, with a specificity of 83%, compared with only 44% by qualitative thallium tomography (p less than 0.001) and a specificity of 92%. Whereas quantitation of thallium activity increased the sensitivity for detecting left circumflex coronary artery stenosis to 80% with a specificity of 55%, it did not achieve statistical significance when compared with qualitative wall motion analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Impaired left ventricular filling and regional diastolic asynchrony at rest in coronary artery disease and relation to exercise-induced myocardial ischemia.

Impaired left ventricular (LV) diastolic filling at rest is frequently observed in patients with coronary artery disease (CAD) who have normal LV systolic function and no previous infarction. To test the hypothesis that abnormal diastolic function at rest might reflect the functional severity of CAD, as estimated by exercise-induced ischemia, the relation between regional and global LV diastolic function at rest and during exercise-induced ischemia was evaluated in 49 patients with radionuclide angiography. All patients had normal systolic function at rest. Group 1 (n = 26) patients manifested a normal ejection fraction response to exercise and group 2 (n = 23) patients an abnormal response. Data obtained from 22 age-comparable normal volunteers were used for comparison. Although regional and global diastolic function were not different between normal subjects and group 1 patients, peak filling rate was lower in group 2 patients than in normal subjects (2.5 +/- 0.8 vs 3.2 +/- 0.6 end-diastolic counts/s; p less than 0.01). Moreover, regional diastolic asynchrony, as assessed from the radionuclide data by using a regional sector analysis of the LV region of interest, was greater in group 2 patients (46 +/- 44 ms) than in both normal subjects (25 +/- 16 ms; p less than 0.05) and group 1 patients (23 +/- 16 ms; p less than 0.05). Thus, among patients with CAD and with normal LV systolic function at rest, impaired LV filling and regional asynchrony predict a greater degree of exercise-induced ischemia, suggesting a greater extent of jeopardized myocardium.

Coronary Circulation↗
PubMed1991

Identification of viable myocardium in patients with chronic coronary artery disease and left ventricular dysfunction. Comparison of thallium scintigraphy with reinjection and PET imaging with 18F-fluorodeoxyglucose.

In patients with chronic coronary artery disease and left ventricular dysfunction, the distinction between ventricular dysfunction arising from myocardial fibrosis and ischemic, but viable, myocardium has important clinical implications. By positron emission tomography (PET), enhanced fluorine-18-labeled fluorodeoxyglucose (FDG) uptake in myocardial segments with impaired function and reduced blood flow is evidence of myocardial viability. Reinjection of thallium-201 at rest immediately after stress-redistribution imaging may also provide evidence of myocardial viability by demonstrating thallium uptake in regions with apparently "irreversible" defects. To compare these two methods, we studied 16 patients with chronic coronary artery disease and left ventricular dysfunction (ejection fraction, 27 +/- 9%), all of whom had irreversible defects on standard exercise-redistribution thallium single-photon emission computed tomography (SPECT) imaging. Thallium was reinjected immediately after the redistribution study, and SPECT images were reacquired. The patients also underwent PET imaging with FDG and oxygen-15-labeled water. A total of 432 myocardial segments were analyzed from comparable transaxial tomograms, of which 166 (38%) had irreversible thallium defects on redistribution images before reinjection. FDG uptake was demonstrated in 121 (73%) of these irreversible defects. Irreversible defects were then subgrouped according to the degree of thallium activity, relative to peak activity in normal regions. Irreversible defects with only mild (60-85% of peak activity) or moderate (50-59% of peak) reduction in thallium activity were considered viable on the basis of FDG uptake in 91% and 84% of these segments, respectively. In contrast, in irreversible defects with severe reduction in thallium activity (less than 50% of peak), FDG uptake was present in 51% of segments. In such severe defects, an identical number of segments (51%) demonstrated enhanced uptake of thallium after reinjection. In these severe "irreversible" defects, data on myocardial viability were concordant by the two techniques in 88% of segments, with 45% identified as viable and 43% identified as scar on both PET and thallium reinjection studies. These observations suggest that thallium imaging can be used to identify viable myocardium in patients with chronic coronary artery disease and left ventricular dysfunction. Most irreversible defects with only mild or moderate reduction in thallium activity represent viable myocardium as confirmed by FDG uptake.(ABSTRACT TRUNCATED AT 400 WORDS)

Coronary Disease↗
PubMed1991

A theoretical comparison of first-pass and gated equilibrium methods in the measurement of systolic left ventricular function.

First-pass and gated equilibrium radionuclide studies of left ventricular function have proven extremely useful in the detection and management of patients with heart disease. Despite this practical experience, however, comparison of these methods generally has been confined to procedural differences that do not reflect the intrinsic properties of the methods. Here, we describe the results of a simple theoretical calculation from first principles that compares the methods based on their relative statistical precision. This analysis assumes that each procedure is carried out with the same tracer dose in the same hypothetical patient under identical conditions and with the same ideal imaging equipment. Results obtained with this model suggest that the imaging time required for a gated equilibrium study to achieve the same statistical precision as a first-pass study is typically less than 2 min in resting subjects and less than 1 min during stress. The analysis also indicates that gated equilibrium studies will tend to possess the greater statistical precision when cardiac output is elevated, such as when the heart is imaged during exercise. On the other hand, this analysis indicates that the first-pass method will tend to possess the greater precision when cardiac output is low and when imaging time is highly constrained.

Gated Blood-Pool Imaging↗
PubMed1991

[Identification of viable myocardium in patients with chronic ischemic disease and left ventricular dysfunction: correlations between blood flow, metabolic activity and regional function].

To identify the presence of viable myocardium in areas of severe systolic dysfunction, we studied 22 patients (age 45 to 78 years) with chronic coronary artery disease and left ventricular dysfunction (mean ejection fraction 29 +/- 9%). All subjects underwent thallium-201 single photon emission computed tomography (SPECT), using the reinjection technique, positron emission tomography (PET) with H2(15)O and 18-fluorodeoxyglucose (FDG) to measure regional blood flow and exogenous glucose uptake, respectively, and nuclear magnetic resonance imaging (MRI). From matched transaxial PET, SPECT and MRI tomograms, a total of 290 left ventricular myocardial regions were analyzed. According to the regional wall thickening, measured from MRI, 3 groups of myocardial regions were identified: akinetic-dyskinetic (n = 60), showing either absence of systolic thickening or systolic thinning; hypokinetic (n = 97), showing an absolute wall thickening less than or equal to 2 mm; normal (n = 133), showing an absolute wall thickening greater than 2 mm. Of the 60 akinetic or dyskinetic regions, 3 were normal by SPECT and 37 corresponded to either a total or partially reversible thallium defect: 34 of these 40 regions also showed presence of FDG uptake by PET. The remaining 20 akinetic or dyskinetic regions showed a thallium defect that remained irreversible after reinjection: in 7 of these 20 regions, however, there was evidence of metabolic activity, as expressed by FDG uptake. Thus, 47 (78%) of the myocardial akinetic or dyskinetic regions showed presence of viable tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Left ventricular hypertrophy and impaired diastolic filling in essential hypertension. Diastolic mechanisms for systolic dysfunction during exercise.

Left ventricular ejection fraction is normal at rest but may respond abnormally to exercise in many patients with essential hypertension. To assess the determinants of the abnormal ejection fraction response to exercise, we performed radionuclide angiography at rest and during exercise in 41 hypertensive patients without coronary artery disease. In 22 patients (group 1), the ejection fraction increased more than 5% during exercise; in the other 19 patients (group 2), the ejection fraction either increased by less than 5% or decreased with exercise. Left ventricular diastolic filling was impaired at rest in patients in group 2 compared with group 1, with reduced peak filling rate (2.5 +/- 0.4 vs. 3.1 +/- 0.7 end-diastolic volume/sec; p less than 0.01) and prolonged time to peak filling rate (175 +/- 28 vs. 153 +/- 22 msec; p less than 0.01). Impaired diastolic filling in group 2 was associated with less augmentation in end-diastolic volume during exercise compared with group 1 (p less than 0.01). These observations were not dependent on the threshold value that was arbitrarily chosen to define an abnormal ejection fraction response, as there were significant correlations for the entire group between the magnitude of change in ejection fraction with exercise and both the resting peak filling rate (r = 0.46) and the change in end-diastolic volume with exercise (r = 0.62).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomegaly↗
PubMed1990

Minimum left ventricular pressure during beta-adrenergic stimulation in human subjects. Evidence for elastic recoil and diastolic "suction" in the normal heart.

The influence of elastic recoil and restoring forces on diastolic left ventricular pressure decay and minimum left ventricular pressures has been demonstrated in animal models but has not been studied in the human heart. To investigate this issue in the normal human left ventricle, we studied eight patients with chest pain and normal coronary arteries with simultaneous measurement of left ventricular volume (by radionuclide angiography) and pressure (by micromanometer catheter) and coronary sinus blood flow. Electrocardiographic-gated data were obtained in the basal state, during rapid atrial pacing, and during isoproterenol infusion to a similar heart rate. Compared with pacing, isoproterenol increased ejection fraction and reduced end-systolic volume (p less than 0.005), end-systolic pressure (p less than 0.005), and the half-time of pressure decline after peak negative dP/dt (T1/2) (p less than 0.001). Negative diastolic pressure developed in seven of eight patients during isoproterenol (range, -0.5 to -2.4 mm Hg) but in only one of eight during pacing (-0.2 mm Hg). These reduced diastolic pressures during isoproterenol were accompanied by increased stroke volume (reflecting increased transmitral flow) and diminished pulmonary wedge pressure (reflecting left atrial pressure). The magnitude of reduction in minimum diastolic pressure during pacing and isoproterenol was related to the change in end-systolic volume (r = 0.79, p less than 0.001), ejection fraction (r = -0.74, p less than 0.001), T1/2 (r = -0.57, p less than 0.02), and coronary sinus flow (r = 0.73, p less than 0.005). Stronger correlations were observed in analyzing changes during isoproterenol alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗
PubMed1990

Comparison of fixed and variable temporal resolution methods for creating gated cardiac blood-pool image sequences.

In each of 50 resting subjects, two gated blood-pool image sequences were created from the same LIST mode data set. One sequence was created using a sorting method that spans each individual cardiac cycle with the same number of images (the "variable temporal" or VT method), while the other (the "fixed temporal" or FT method) spans the average cardiac cycle with images of fixed temporal duration. Left ventricular time-activity curves were extracted from each sequence using identical regions-of-interest and analyzed with identical methods to obtain estimates of ejection fraction, peak ejection rate, peak filling rate, and the times of occurrence of these peak rates. Differences among certain of these parameters in kind and amount support the hypothesis that estimates of resting cardiac function are more accurately portrayed by the FT method. The magnitudes of these differences are small for systolic parameters but large for early diastolic parameters. Thus, although both methods might be used for measuring systolic function, the FT method will yield a more accurate estimate of peak filling rate in resting subjects.

Gated Blood-Pool Imaging↗
PubMed1989

Influence of temporal smoothing on quantitation of left ventricular function by gated blood pool scintigraphy.

Frequently, indexes of systolic and diastolic left ventricular (LV) function obtained from radionuclide angiography are computed after the LV time-activity curve has been temporally smoothed. This smoothing process may introduce important systematic errors into the analysis. To assess this potential effect, high temporal resolution time-activity curves (20 ms/point) were obtained in 113 normal subjects, 175 patients with coronary artery disease and 171 patients with hypertrophic cardiomyopathy. The curves were then subjected to 0-, 3-, 5-, 7- and 9-point temporal smoothing. In each group, increased smoothing progressively and consistently underestimated ejection fraction by up to 5% (p less than 0.001) and peak ejection rate by up to 14% (p less than 0.001). A greater effect on peak filling rate was observed: 5-point and 9-point smoothing reduced peak filling rate by 10% and 23% in normal subjects, 3% and 10% in patients with coronary artery disease and 7% and 15%, respectively, in patients with hypertrophic cardiomyopathy (all p less than 0.001). These errors were compounded further when the same data obtained at lower temporal resolution (40 ms/point) were analyzed: 5-point and 9-point smoothing resulted in underestimation of peak filling rate by 20% and 46% in normal subjects, 13% and 43% in coronary artery disease and 16% and 34% in hypertrophic cardiomyopathy. The underestimation was not uniform, and its magnitude varied considerably among individuals in each of the 3 groups. Thus, smoothing of LV time-activity curves may result in significant systematic errors in computation of indexes of LV systolic and diastolic function, especially in data with poor temporal resolution. These concepts apply to other imaging methods, such as magnetic resonance imaging and cine-computed tomography, that assess LV function from the LV volume curve. Although ejection fraction is affected only mildly by these errors, both peak filling rate and peak ejection rate may be severely underestimated.

Algorithms↗
PubMed1989

Comparative effects of verapamil and nitroprusside on left ventricular function in patients with hypertension.

The effects of verapamil were compared with those of nitroprusside at matched mean arterial pressures and heart rates in 10 symptomatic hypertensive patients during cardiac catheterization. Simultaneous radionuclide angiography and micromanometer pressure measurements were obtained to assess left ventricular pressure-volume relations. Compared with control conditions, verapamil increased left ventricular end-diastolic volume index from 57 +/- 16 to 70 +/- 28 ml/m2 (p = 0.05) without a significant increase in left ventricular end-diastolic pressure (from 10 +/- 4 to 13 +/- 6 mm Hg). Despite a downward and rightward shift in the end-systolic pressure-volume relation indicating negative inotropic effects, ejection fraction did not decrease significantly (from 52 +/- 9% to 46 +/- 9%); cardiac index and stroke volume index remained unchanged. The change in stroke volume index with verapamil was directly related to the magnitude of change in end-diastolic volume index (r = 0.82, p less than 0.005), suggesting that the increase in end-diastolic volume did not arise purely from negative inotropic effects. Systemic vascular resistance index decreased from 42 +/- 8 to 34 +/- 7 mm Hg.min.m2/liter (p less than 0.05). In contrast, nitroprusside decreased left ventricular end-diastolic volume index from 57 +/- 16 to 41 +/- 10 ml/m2 (p less than 0.05), cardiac index from 3.2 +/- 0.7 to 2.8 +/- 0.6 liters/min per m2 (p less than 0.05) and stroke volume index from 28 +/- 6 to 24 +/- 5 ml/m2 (p less than 0.01), with no change in systemic vascular resistance index (40 +/- 10 mm Hg.min.m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Beta-adrenergic stimulation with isoproterenol enhances left ventricular diastolic performance in hypertrophic cardiomyopathy despite potentiation of myocardial ischemia. Comparison to rapid atrial pacing.

Impaired left ventricular relaxation and filling is an important pathophysiologic mechanism in hypertrophic cardiomyopathy. To determine whether isoproterenol, known to improve relaxation in isolated cardiac muscle, could favorably modify this effect, we assessed simultaneous left ventricular volume and regional systolic asynchrony (by radionuclide angiography), left ventricular pressure (by micromanometer catheters), and lactate metabolism in 12 patients with hypertrophic cardiomyopathy. Pressure-volume relations were studied during atrial pacing stress to induce myocardial ischemia and during isoproterenol infusion to similar heart rates. Angina occurred in 10 patients with pacing and in 11 patients during isoproterenol infusion; lactate consumption was reduced in nine patients during isoproterenol compared with pacing, including five patients who produced lactate with isoproterenol. During isoproterenol compared with pacing, peak left ventricular pressure was higher (205 +/- 33 vs. 142 +/- 21 mm Hg, p less than 0.001), ejection fraction was higher (77 +/- 10% vs. 71 +/- 12%, p less than 0.02), and regional systolic nonuniformity was diminished. Despite ischemia, these changes in load and nonuniformity during isoproterenol were associated with enhanced diastolic function compared with pacing tachycardia: isoproterenol reduced T 1/2, the half-time of pressure decline after peak negative dP/dt (from 46 +/- 10 to 33 +/- 6 msec, p less than 0.001), shifted the diastolic pressure-volume curve downward and rightward in 10 of 12 patients, and increased end-diastolic volume (from 77 +/- 18% to 100 +/- 11% of control values, p less than 0.001) with no change in end-diastolic pressure (19 +/- 7 to 19 +/- 5 mm Hg, p = NS). Thus, despite ischemia, isoproterenol improved left ventricular relaxation and filling compared with tachycardia in the absence of beta-adrenergic stimulation. Although isoproterenol is detrimental in hypertrophic cardiomyopathy by provoking ischemia, these data suggest that the adverse effects of ischemia on ventricular relaxation and distensibility may be alleviated by beta-adrenergic stimulation, possibly as a result of enhanced inactivation and restored load sensitivity.

Adult↗
PubMed1989

Verapamil prevents silent myocardial perfusion abnormalities during exercise in asymptomatic patients with hypertrophic cardiomyopathy.

Recent studies indicate that reversible 201Tl perfusion defects, compatible with silent myocardial ischemia, commonly develop during exercise in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy (HCM). To determine whether this represents a dynamic process that may be modified favorably by medical therapy, we studied 29 asymptomatic or minimally symptomatic patients with HCM, aged 12-55 years (mean, 28), with exercise 201Tl emission computed tomography under control conditions and again after 1 week of oral verapamil (mean dosage, 453 mg/day). Treadmill time increased slightly during verapamil (21.0 +/- 3.6 to 21.9 +/- 2.7 minutes, p less than 0.005), but peak heart rate-blood pressure product was unchanged (26.3 +/- 6.0 X 10(3) compared with 25.0 +/- 6.4 X 10(3). Two midventricular short-axis images per study were divided into five regions each, and each of these 10 regions was then analyzed on a 0-2 scale by three observers blinded with regard to the patients' therapy. Average regional scores of 1.5 or less were considered to represent perfusion defects, and a change in regional score of 0.5 or more was considered to constitute a significant change. During control studies, 15 patients (52%) developed perfusion defects with exercise (average, 3.7 regions per patient). In 14 of these patients, all perfusion defects completely reversed after 3 hours of rest; one patient had fixed defects. After administration of verapamil, exercise perfusion scores improved in 10 of the 14 patients (71%) with reversible defects; there was overall improvement in 34 of 50 (68%) regions with initially reversible perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Diagnosis of coronary artery disease by radionuclide angiography: effect of combining indices of left ventricular function.

The aim of this study was to determine whether the diagnostic capability of radionuclide angiography (RNA) in detecting coronary artery disease (CAD) might be improved by using several indices of left ventricular (LV) function in concert. Three different models (rest data, exercise data, and rest plus exercise data) were derived by stepwise multivariate discriminant analysis of RNA data in 65 normal volunteers and 111 patients with CAD and normal ejection fraction (EF) at rest. The model with only resting indices yielded a diagnostic capability comparable to the simple measure of EF response to exercise (area under receiver operating characteristic curve = 89% and 91%, respectively). Both the exercise and rest plus exercise models gave better results (area = 94% and 97%, respectively), but only the rest plus the exercise model was better than the EF response alone (p less than 0.001). Thus (a) if resting studies alone are performed, the diagnostic potential of RNA may be improved by combining several indices of resting function; and (b) combined rest and exercise data may improve the sensitivity of RNA in detecting CAD over what could be obtained with the EF response to exercise alone.

Adult↗