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Biomedical subjects

W L Ashburn

Publications and source records attributed to W L Ashburn.

At least 37 records · Page 2Linked to original sources
PubMed1983

Radionuclide analysis of peak filling rate, filling fraction, and time to peak filling rate. Response to supine bicycle exercise in normal subjects and patients with coronary disease.

Using gated equilibrium radionuclide angiography, variables of diastolic filling were analyzed at rest and during supine bicycle exercise in normal subjects (Group 1, n = 18), coronary patients with normal resting ejection fractions (Group 2, n = 26), and coronary patients with reduced resting ejection fractions (Group 3, n = 8). Indexes analyzed were peak filling rate and filling fraction during the first third of diastole. At rest, the peak filling rate was significantly lower in coronary patients than in normal subjects (3.18 +/- 0.82 end-diastolic volume [EDV]/s in Group 1 versus 2.41 +/- 0.66 EDV/s in Group 2, p less than 0.005; and 1.34 +/- 0.26 EDV/s in Group 3, p less than 0.001 versus Group 1). These differences persisted at peak exercise. Coronary patients also had significantly lower filling fractions at rest and during exercise than did normal control subjects. The time from end-systole to peak filling rate was longer at rest in patients in Group 2 (203 +/- 52 ms) than in subjects in Group 1 (172 +/- 50 ms, p less than 0.025). This remained true when the time to peak filling was normalized by the R-R interval. Although the exercise time to peak filling was longer in coronary patients in both Groups 2 and 3 than in Group 1, these differences were not apparent when the interval was normalized by the R-R interval. Thus, abnormalities in peak filling rate and filling fraction exist in patients with coronary disease both at rest and during exercise, but large overlaps exist between normal and coronary patients. Caution is advised in comparing the timing of events during diastole because apparent group differences may be related in part to rest or exercise heart rate.

Adult↗
PubMed1983

Radionuclide analysis of ejection time, peak ejection rate, and time to peak ejection rate: response to supine bicycle exercise in normal subjects and in patients with coronary heart disease.

Using equilibrium radionuclide angiography, we evaluated the ejection time (ET), peak ejection rate (PER), and time to peak ejection rate (TTp) at test and during supine bicycle exercise in 39 subjects, divided into three groups: group 1 = 13 normal subjects; group 2 = 10 patients with a previous infarction (MI); and group 3 = 16 patients with coronary disease without a previous MI. Normal subjects had greater ejection fractions and PERs than the other two groups at rest or peak exercise (p less than 0.05). PER was no more useful than ejection fraction in identifying cardiac dysfunction at either rest or exercise. The time of its occurrence varied with the group studied, and was slightly but significantly later in systole in groups 2 and 3 when compared to normals (p less than 0.05), though substantial overlap between groups occurred. During exercise, absolute ET shortened in all groups, but actually increased as a function of the R-R interval. The time to peak ejection rate (normalized for the R-R interval) was greater in the noninfarct group (group 3) patients (p less than 0.05) when compared to the group 1 or group 2 individuals at peak exercise. In conclusion, equilibrium radionuclide angiography is a useful technique for the quantification and characterization of events during systole, and is capable of providing information on the timing of events during ejection. Tardokinesis, or the delay of ventricular ejection, is not seen in the response of global indices of left ventricular function to exercise stress. While global early systolic indexes may not detect regional dyssynchrony, their timing during stress may occasionally aid in discerning the presence of cardiac dysfunction.

Adult↗
PubMed1983

Quantitative phase analysis of exercise radionuclide left ventriculography in normals and patients with coronary artery disease.

Using multigated radionuclide ventriculography (RNV), the left ventricular (LV) phase histogram (PH) was used to quantitate LV synchrony at rest and at submaximal and maximal supine exercise in 10 normal and 10 coronary (CAD) patients. Each LV PH was obtained by masking the phase image with an LV region, generated semiautomatically and modified if necessary to minimize ambiguity of LV delineation. The shape and spread of each histogram was characterized by its standard deviation (SD) and skewness (SK). Normals had a tight resting PH with slight negative skewness (SD = 9.06 +/- 0.22 (mean +/- SEM; SK = -0.53 +/- 0.05). CAD patients had a wider resting PH with a larger SD and a significantly more positive skewness reflecting greater contractile asynchrony (SD = 16.53 +/- 2.26; SK = 0.35 +/- 0.22). With exercise the PH distribution for the normals remained tight (SD = 8.1 +/- 0.24) while SK changed little (SK = -0.29 +/- 0.04). In contradistinction, with exercise CAD patients markedly increased the spread of their LV PH (SD = 27.42 +/- 3.77) and increased the number of late pixels (SK = 0.75 +/- 0.15). It is concluded that quantitative PH analysis is a useful adjunct for the analysis of regional asynergy during resting or exercise radionuclide left ventriculography.

Coronary Disease↗
PubMed1983

Quantitative assessment of segmental wall motion abnormalities at rest and after atrial pacing using digital intravenous ventriculography.

Digital intravenous ventriculography lends itself readily to quantitative assessment of ventricular wall motion with computer algorithms. Forty-five patients referred for cardiac catheterization were studied by digital intravenous ventriculography (mask mode) and direct ventriculography in the 30 degrees right anterior oblique position. Quantitative wall motion was analyzed by a radial shortening method applied to both studies. Lower limits of normal radial shortening were determined for each technique and used to determine the presence or absence of wall motion disorders. The inter- and intraobserver variability of radial shortening measurements was +/- 5.3 and +/- 8.8%, respectively, with maximal discrepancies of -6 and +7% fractional shortening units. The overall agreement between the two techniques in wall motion assessment was 87% (274 of 315 radii). A subset of patients also underwent atrial pacing, and a second digital intravenous ventriculogram was obtained (5 normal subjects and 15 patients with coronary artery disease). Although analysis of wall motion at rest showed a poor sensitivity for detection of significant coronary stenoses, nine of nine patients with coronary artery disease and normal wall motion at rest showed a quantitative decrease in radial wall motion after atrial pacing. Thus, digital intravenous ventriculograms can be used to provide quantitative wall motion analyses that show a high degree of agreement with those of standard, direct left ventriculography. Atrial pacing can be used to increase the sensitivity of wall motion analysis for the detection of significant coronary disease.

Aged↗
PubMed1983

Patterns of pulmonary perfusion scans in normal subjects. III. The prevalence of abnormal scans in nonsmokers 30 to 49 years of age.

The prevalence of abnormal pulmonary perfusion (Q) scans in persons without cardiopulmonary disease has not been well defined; this prevalence could impact on the current diagnostic approach to those in whom pulmonary embolic disease is suspected. In prior studies, we found that Q scan defects, particularly lobar or segmental defects, are rarely present in normal young smokers and nonsmokers. To determine if normal nonsmokers of an older age group have a higher prevalence of Q defects, we performed 6-view Q scans in 40 subjects 32 to 49 yr of age who had no known cardiopulmonary disease. Each subject had undergone a history, physical examination, electrocardiogram, spirometry, and posteroanterior chest roentgenogram prior to scanning. All Q scans were interpreted blindly and independently by 2 experienced readers. No subject demonstrated a lobar or segmental defect on 2 views. One subject with scoliosis had a subsegmental defect corresponding to a prominent aortic arch on the chest roentgenogram. We conclude that abnormal Q scans are extremely uncommon among normal nonsmokers 30 to 49 yr of age.

Adult↗
PubMed1982

Right and left ventricular response to subcutaneous terbutaline in patients with chronic obstructive pulmonary disease: radionuclide angiographic assessment of cardiac size and function.

To assess the response of the right and left ventricles to the subcutaneous administration of terbutaline sulfate, a beta-2 selective agonist, we evaluated 14 patients with chronic obstructive pulmonary disease (COPD) with equilibrium radionuclide angiography (RNA). Prior to injection, eight patients (57%) had an abnormal right ventricular ejection fraction (RVEF), four (29%) had a low left ventricular ejection fraction (LVEF), and three (21%) had low ejection fractions of both ventricles. After terbutaline injection, RVEF increased in 13 of 14 patients (93%) by 17 +/- 8% (p less than 0.001) while LVEF increased in all patients by 15 +/- 7% (p less than 0.001). Both left and right ventricular end-diastolic volumes decreased (p less than 0.01), while stroke volume was unchanged. Cardiac output rose by 0.8 +/- 1.3 L/min (p less than 0.05), primarily due to the increase in heart rate (10 bpm, p less than 0.001), since stroke volume did not significantly change. We conclude that in patients with COPD subcutaneous terbutaline has significant beta-1 cardiac effects; it increases the heart rate and decreases cardiac size.

Aged↗
PubMed1982

Validation of cardiac output estimates by digital video subtraction angiography in dogs. Correlation with thermodilution values.

To determine the validity of cardiac output estimates obtained by digital video subtraction angiography (DVSA), they were compared with thermodilution values in 6 anesthetized dogs. Multiple levels of cardiac output were produced in each dog by graded openings of peripheral arteriovenous fistulas. Both direct contrast and mask-mode images were evaluated. There was good correlation between thermodilution and direct contrast values (r = 0.88) as well as between thermodilution and mask-mode values (r = 0.89), though the mask-mode outputs were 12 +/- 1.1% less than the direct contrast values (p less than 0.05). Direct contrast and mask-mode values correlated well (n = 6; r greater than or equal to 0.95). Digital outputs exhibited little variation, indicating excellent reproducibility. These results demonstrate the validity of area-length estimates of cardiac output by DVSA.

Angiocardiography↗
PubMed1982

A noncomputerized count-based technique for the determination of resting left ventricular ejection fraction.

A noncomputerized, count-based technique for the determination of left ventricular ejection fraction (LVEF), which does not use geometric assumptions of left ventricular shape, was developed. The noncomputerized technique and computerized multigated ventriculography using both fixed and variable region-of-interest (ROI) methods were performed on 16 patients. The LVEFs obtained with the noncomputerized technique correlated well with both the fixed ROI computerized technique (r = .87) and the variable ROI computerized technique (r = .86). It is concluded that when a computer is not available, the noncomputerized technique is a valid alternative for the determination of LVEF in resting patients in stable sinus rhythm.

Cardiac Output↗
PubMed1982

Quantitation of left ventricular dimensions and function by digital video subtraction angiography.

Digital video subtraction angiography (DVSA) after central intravenous administration of contrast media was used in experimental animals and in patients with suspected coronary artery disease to quantitate left ventricular dimensions and regional and global contractile function. In animals, measurements of left ventricular (LV) volumes, wall thickness, ejection fraction, segmental contraction, and cardiac output correlated closely with sonocardiometry or thermodilution measurements. In patients, volumes and ejection fractions calculated from mask mode digital images correlated closely with direct left ventriculography. Global and segmental contractile function was displayed in patients by ejection shell images, stroke volume images, and time interval difference images. Central cardiovascular function was also quantitated by measurement of pulmonary transit time and calculation of pulmonary blood volume from digital fluoroscopic images. DVSA was shown to be useful and accurate in the quantitation of central cardiovascular physiology.

Angiocardiography↗
PubMed1982

Patterns of pulmonary perfusion scans in normal subjects.

The prevalence of abnormal pulmonary perfusion (Q) scans in persons without cardiopulmonary disease could condition the usefulness of the Q scan in the evaluation of patients in whom pulmonary embolism is suspected. In a recent study, we found that Q scan defects, particularly lobar or segmental defects, are rarely present in normal young nonsmokers. To determine if normal smokers of the same age group have a higher prevalence of Q defects, we performed 6 view Q scans in 40 subjects 18 to 29 yr of age who had no known active cardiopulmonary disease. Each subject had undergone a history, physical examination, electrocardiogram, spirometry, and posteroanterior chest roentgenogram prior to scanning. All Q scans were interpreted blindly and independently by 2 experienced readers. None of the 40 subjects was found to have an abnormal Q scan defined as the presence of a lobar, segmental, or subsegmental defect on 2 views. When these data were compared with our previous study, statistical analysis found no difference in the prevalence of abnormal Q scans in the 2 groups. We conclude that among young normal persons, abnormal Q scans are extremely uncommon and the prevalence of significant Q defects is not influenced by smoking.

Adolescent↗
PubMed1982

Longterm follow-up of patients with suspected pulmonary embolism and a normal lung scan. Perfusion scans in embolic suspects.

There is widespread acceptance of the thesis that in a patient with suspected embolism, a normal perfusion lung scan excludes the diagnosis of acute pulmonary embolism. However, limited published data exist which validate this thesis. We have explored this question by longitudinal follow-up of 68 patients who were referred for lung scanning to rule out embolism and proved to have normal perfusion lung scans. Risk factors for venous thromboembolism among these patients were similar to those reported in prior series of patients with pulmonary embolism. Our data support the widely-held views that: 1) a normal perfusion lung scan excludes the diagnosis of clinically significant pulmonary emboli; 2) the diagnostic work-up for suspected pulmonary embolism need not extend beyond a normal perfusion scan; 3) anticoagulant therapy can be discontinued after a normal perfusion scan, except in the presence of documented venous thrombosis; and 4) a normal lung scan has the same value in ruling out embolism in man as does a normal pulmonary angiogram.

Adult↗
PubMed1981

The value of nuclear bone imaging in advanced prostatic cancer.

The nuclear bone scan is a highly sensitive means of detecting skeletal metastasis in patients with prostatic cancer. Serial bone imaging provides an accurate method to follow the response of osseous metastases to treatment and to detect relapsing disease in the skeleton. In selected instances the nuclear bone scan can provide information about vertebral metastases that can be important for planning palliative treatment of pain.

Bone Neoplasms↗
PubMed1981

Gallium-67-citrate uptake in a case of acne vulgaris.

A case of increased Ga-67 uptake in a patient with active acne vulgaris is reported. The scan was requested in a search for metastatic testicular carcinoma or bleomycin pulmonary toxicity. Careful clinical evaluation including physical examination was necessary in order to avoid an erroneous scan interpretation.

Acne Vulgaris↗
PubMed1981

Patterns of pulmonary perfusion scans in normal subjects.

A vital factor conditioning the usage of the pulmonary perfusion (Q) scan in the evaluation of patients suspected of pulmonary embolism is the prevalence of abnormal Q scans in subjects free of cardiopulmonary disease. Because this prevalence has not been well defined, we performed Q scans in 80 nonsmoking subjects 18 to 29 yr of age having no known active cardiopulmonary disease. Each subject underwent a history, physical examination, electrocardiogram, spirometry, and PA chest roentgenogram, followed by a 6-view Q scan. Two subjects in whom a Q defect was suspected underwent a 133Xe equilibrium-washout ventilation (V) scan. All Q scans were interpreted blindly and independently by 2 experienced readers. Seventy-nine of the 80 Q scans were read as normal. No subject demonstrated a lobar or segmental defect. One of the 80 subjects, who had a mild pectus excavatum, had a left upper lobe subsegmental defect, which was not seen on the V scan. Based on the statistical analysis of these data, no more than 3.68% of normal nonsmoking persons in this age group may have a lobar or segmental Q scan defect and no more than 6.77% may have a subsegmental defect (with 95% confidence). Therefore, our study indicated that Q scan defects, particularly lobar or segmental, are rarely present among normal nonsmokers in this age group.

Adolescent↗
PubMed1980

Right and left ventricular dysfunction in patients with chronic obstructive lung disease. Assessment by first-pass radionuclide angiography.

To evaluate the relationship between right and left ventricular function in patients with obstructive lund disease, we studied 10 normal subjects (group 1) and 37 patients with chronic obstructive pulmonary disease by first pass radionuclide angiography. These 37 patients were divided into three groups: nine with mild chronic obstructive pulmonary disease (group 2), 20 with severe chronic obstructive pulmonary disease (group 3) and eight with severe chronic obstructive pulmonary disease and primary left ventricular disease (group 4). In each subject right ventricular ejection fraction (RVEF), left ventricular ejection fraction (LVEF) and ejection fraction during first third of systole (first third LVEF) were calculated. (For table: see text.) p less than 0.05 versus 1. All subjects in group 2 had normal left ventricular and right ventricular function. In group 3, 11 of 10 (55 per cent) had a low RVEF and three of 20 (15 per cent) a low LVEF. However eight of 20 in this group (40 per cent) had a depressed first-third LVEF. The correlation between decline in RVEF and first-third LVEF was good r = 0.73. We conclude that (1) certain indices of early systolic left ventricular ejection are abnormal in many patients with chronic obstructive pulmonary disease and correlate with the decline in right ventricular function; (2) this is not seen in patients with mild chronic obstructive pulmonary disease and is worse in patients with underlying left-sided heart disease.

Adult↗
PubMed1980

Comparison of rest/exercise ECG, thallium-201 scans and radionuclide angiography in patients with suspected coronary artery disease.

The results of rest and exercise ECG, 201Tl myocardial perfusion imaging and equilibrium radionuclide angiography were analyzed in 71 consecutive patients referred for diagnosis or evaluation of coronary artery disease (CAD). In 45 patients the diagnosis was established either by catheterization or typical history. In this group the overall sensitivity for rest/exercise ECG was 66%, for 201Tl scans 74%, for both combined 79% and for the ejection fraction response to exercise determined by radionuclide angiography 97%. If only the exercise response was considered, the corresponding sensitivity values were 58% (ECG), 50% (201Tl scans), 71% (ECG + 201Tl) and 97% (radionuclide angiography). The specificity for coronary artery disease was determined to be 71% for ECG, 86% for 201Tl scans and 42% for radionuclide angiography. All patients with false-positive results by radionuclide angiography had cardiomyopathies, thus this test has a high specificity for left ventricular dysfunction rather than for CAD alone. Criteria developed from the analysis of the test results in the 45 patients with definite diagnoses were then applied to the evaluation of 26 additional patients with atypical chest pain. A diagnosis could be made in all but 5 of them and radionuclide angiography was again the single most reliable test. Based on this study a new approach for the noninvasive evaluation of patients with suspected coronary artery disease is proposed.

Angiography↗