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Biomedical subjects

H D Royal

Publications and source records attributed to H D Royal.

At least 19 recordsLinked to original sources
PubMed1992

Thyroid nodules in the population living around Chernobyl.

OBJECTIVE: To determine the baseline incidence, prevalence, and characteristics of thyroid nodules in the population living around the Chernobyl nuclear power plant and to compare the findings with unexposed populations. DESIGN: Prevalence study. Population samples from seven highly contaminated villages were compared with six nearby control villages of the same size and type. The data were obtained as part of the International Chernobyl Project conducted in 1990. SETTING: The study was conducted 4.5 years after the Chernobyl reactor accident that released large quantities of radionuclides, including radioiodine. PATIENTS OR OTHER PARTICIPANTS: Population samples of approximately 100 persons residing in both highly contaminated villages and control villages since the accident were compared. Individuals were selected on the basis of birth date as being 5, 10, 40, or 60 years old at the time of the study. All persons selected underwent a thyroid examination. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Two main outcome measures were used, both for thyroid nodularity: clinical palpation and high-resolution ultrasonography. RESULTS: There was no significant difference in thyroid nodularity between the study groups. Nodules were palpated in 0.7% of children and 2.9% of adults. Discrete nodules were found by ultrasonography in 0.5% of children and 14.9% of adults. Multinodular goiter was found in 3% of adults. Nodules were more common in females. CONCLUSIONS: Four and a half years after the Chernobyl accident, the incidence, prevalence, and characteristics of thyroid nodules were the same in population samples from both highly contaminated and control settlements and similar to results reported for unexposed populations in other countries.

Accidents↗
PubMed1992

Blinded clinical evaluation of positron emission tomography for diagnosis of probable Alzheimer's disease.

We evaluated the sensitivity and specificity of positron emission tomography for diagnosis of probable Alzheimer's disease under conditions similar to those encountered in the routine clinical practice of nuclear medicine. We obtained tomographic images of regional cerebral blood flow from three groups of subjects: (1) 13 subjects, ages 69 to 84, who had probable Alzheimer's disease diagnosed by validated clinical criteria; (2) 15 subjects, ages 57 to 77, who had Parkinson's disease without dementia; and (3) 11 subjects, ages 65 to 83, who were normal. Three blinded reviewers, who had not previously seen the images, categorized them as normal, bilateral temporoparietal flow defects typical of Alzheimer's disease, or other abnormality. Consensus interpretation demonstrated sensitivity of 0.38 (5/13) and specificity of 0.88 (23/26) for identifying patients with probable Alzheimer's disease. Thus, the criterion of bilateral temporoparietal reduction in cerebral blood flow used in this study did not have sufficient sensitivity to be of clinical value. While other criteria may be developed to improve diagnostic accuracy, clinical utility can be established only by testing for validity in patients with a full spectrum of complicating neurologic and psychiatric conditions for whom diagnosis is uncertain and who are then followed longitudinally to determine clinical outcome or pathologic findings.

Aged↗
PubMed1992

Evaluation of a single injection of 99mTc-labeled diethylenetriaminepentaacetic acid for measuring glomerular filtration rate in horses.

Glomerular filtration rate (GFR) was measured in 12 clinically normal horses, using the standard inulin clearance method, and values were compared with values for 2 methods, using a single rapid IV injection of 99mTc-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA). The first 99mTc-DTPA method used a 2-compartment model to calculate GFR blood clearance of the tracer. The second method used sequential digital gamma camera images of the kidneys to determine fractional accumulation of the total dose of the tracer in the kidneys (percentage of injected dose, gamma camera) from 0 to 10 minutes after radionuclide administration. Linear correlation among the 3 methods was determined. Mean (+/- SD) GFR, using the inulin clearance method, was 154.67 +/- 42.28 ml/min/100 kg of body weight. Mean GFR, using the 2-compartment blood clearance curve, was 146.92 +/- 27.49 ml/min/100 kg. Mean GFR, using percentage of injected dose (gamma camera method) was 154.7 +/- 22.00 ml/min/100 kg. The percentage of injected dose (gamma camera method) did not correlate significantly to the inulin clearance results. However, a significant (r = 0.666, P less than 0.018) correlation was observed between the inulin method and the 99mTc-DTPA blood clearance method. Significant (P less than 0.0001) difference also was observed in the split function of the equine kidneys, with GFR of the right kidney contributing 60.1 +/- 9.12% of the total function, as determined by 99mTc-DTPA gamma camera imaging. Because the 99mTc-DTPA blood clearance method does not require urine collection, it may be a more practical procedure to measure GFR in the horse.

Animals↗
PubMed1991

Comparison of differences in the hemodynamic response to passive postural stress in healthy subjects greater than 70 years and less than 30 years of age.

To test the hypothesis that age-related increases in arterial pressure alter the cardiovascular response to physiologic stress, 9 healthy elderly volunteers (74 +/- 2 years) and 7 young subjects (27 +/- 3 years) were subjected to a standard 60 degrees upright tilt. Cardiac volumes were measured with patients in the supine position and 5 minutes after they assumed an upright posture using radionuclide ventriculography, while heart rate, blood pressure and forearm cutaneous flow were recorded continuously and simultaneously. Only the expected age-related increase in mean arterial pressure (young subjects, 79 +/- 1 mm Hg; elderly subjects, 99 +/- 3 mm Hg; p less than 0.001) distinguished the 2 groups at baseline. However, during upright tilt, elderly subjects had significant decreases in stroke volume (supine [108 +/- 9 ml] vs upright [78 +/- 9 ml]; p less than 0.01) and cardiac index (supine [3.4 +/- 0.2 liters/min/m2] vs upright [2.8 +/- 0.2 liters/min/m2]; p less than 0.05) because of an inability to reduce end-systolic volume (supine, 44 +/- 6 ml; upright, 51 +/- 7 ml); however, mean arterial pressure was maintained through an increase in peripheral resistance. In contrast, the young relied solely on cardiac adaptations to postural stress by decreasing end-systolic volume (supine, 62 +/- 5 ml; upright, 39 +/- 5 ml; p less than 0.01) and increasing heart rate (57 +/- 2 min-1 to 71 +/- 3 min-1, p less than 0.01), whereby cardiac output and mean arterial pressure were maintained during tilt.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Utility of radioisotopic filtration markers in chronic renal insufficiency: simultaneous comparison of 125I-iothalamate, 169Yb-DTPA, 99mTc-DTPA, and inulin. The Modification of Diet in Renal Disease Study.

Assessment of glomerular filtration rate (GFR) with inulin is cumbersome and time-consuming. Radioisotopic filtration markers have been studied as filtration markers because they can be used without continuous intravenous (IV) infusion and because analysis is relatively simple. Although the clearances of 99mTc-diethylenetriamine-pentaacetic acid (DTPA), 169Yb-DTPA, and 125I-iothalamate have each been compared with inulin, rarely has the comparability of radioisotopic filtration markers been directly evaluated in the same subject. To this purpose, we determined the renal clearance of inulin administered by continuous infusion and the above radioisotopic filtration markers administered as bolus injections, simultaneously in four subjects with normal renal function and 16 subjects with renal insufficiency. Subjects were studied twice in order to assess within-study and between-study variability. Unlabeled iothalamate was infused during the second half of each study to assess its effect on clearances. We found that renal clearance of 125I-iothalamate and 169Yb-DTPA significantly exceeded clearance of inulin in patients with renal insufficiency, but only by several mL.min-1.1.73m-2. Overestimation of inulin clearance by radioisotopic filtration markers was found in all normal subjects. No differences between markers were found in the coefficient of variation of clearances either between periods on a given study day (within-day variability) or between the two study days (between-day variability). The true test variability between days did not correlate with within-test variability. We conclude that the renal clearance of 99mTc-DTPA, 169Yb-DTPA, or 125I-iothalamate administered as a single IV or subcutaneous injection can be used to accurately measure GFR in subjects with renal insufficiency; use of the single injection technique may overestimate GFR in normal subjects.

Creatinine↗
PubMed1990

Reduced supine cardiac volumes and diastolic filling rates in elderly patients with chronic medical conditions. Implications for postural blood pressure homeostasis.

Very elderly individuals with multiple chronic illnesses are at high risk of orthostatic hypotension, falls, and associated morbidity and mortality. Alterations in cardiac volumes and filling characteristics may contribute in part to an increased prevalence of orthostatic hypotension and falls in these people. In this study cardiac function was evaluated with gated radionuclide ventriculography in eight healthy young subjects (19-38 years) and 25 elderly persons with stable chronic illnesses (73-96 years), 14 of whom had a history of recurrent falls. Blood pressure was measured supine during the radionuclide ventriculography, then after one minute of standing. Supine stroke volume index, end diastolic volume index, cardiac index, and peak filling rates were significantly lower in elderly subjects compared to young, and ejection fraction and end systolic volume index (measures of systolic function) were the same in young and old. Compared to the young, elderly subjects had a reduction in ventricular filling during the first third of diastole, but an augmentation in the last third, during atrial contraction. Within the group of elderly subjects, the directional change in systolic blood pressure during orthostasis was significantly correlated with basal supine systolic blood pressure (R = 0.81, P less than .0001) and supine cardiac index (R = 0.66, P = .002). Thus, very old people representative of those seen in clinical practice have reduced cardiac volumes and impaired early diastolic filling, a result possibly related to elevations in systolic blood pressure. These changes in cardiac structure and function may contribute, in part, to orthostatic hypotension in advanced age.

Accidental Falls↗
PubMed1988

Myocarditis presenting as acute myocardial infarction.

Ten patients with acute myocarditis, who were initially seen with clinical signs of acute myocardial infarction, will be discussed. All had symptoms and seven had laboratory evidence of an acute viral infection. Acute cardiac findings consisted of chest pain in nine patients, compatible ECGs and elevated creatine kinase levels in 10, positive MB fractions in eight, and regional wall motion abnormalities in eight. Acutely, the left ventricular ejection fraction was less than 55% in six patients; ventricular ectopy occurred in five patients, bundle branch block in four, transient junctional escape rhythm in three, and congestive heart failure in three. Among the nine patients followed-up for 1 to 14 months there was one death, five patients had normal results of exercise tests, and three had normal coronary angiograms. Wall motion abnormalities persisted in four patients; ejection fraction improved in five and was less than 55% in three. These findings suggest that focal myocardial damage may occur during acute viral myocarditis and mimic acute myocardial infarction resulting from atherosclerotic coronary artery disease.

Adult↗
PubMed1988

Time course of left ventricular dilation after myocardial infarction: influence of infarct-related artery and success of coronary thrombolysis.

Dilation of the left ventricle after myocardial infarction is common, occurs rapidly (within 2 weeks of infarction) and may be self-limited. To evaluate the time course of postinfarction left ventricular dilation and to assess the impact of successful coronary thrombolysis, serial radionuclide left ventricular volume analyses were performed in 36 patients undergoing attempted thrombolysis for acute transmural myocardial infarction. All patients underwent cardiac catheterization, coronary angiography and attempted thrombolysis within 7 h of the onset of symptoms. The site of coronary occlusion was the left anterior descending coronary artery in 17 patients, the right coronary artery in 18 and, in 1 patient, occluded bypass grafts to the right and left circumflex coronary arteries. Attempted reperfusion using a thrombolytic agent was successful in 22 individuals, occurring 5 +/- 1 h after the onset of symptoms. Gated radionuclide ventriculography was performed early (mean time 1 day after admission, n = 36), subacutely (mean time 11 days postinfarction, n = 36) and late after infarction (mean time 10.5 months, n = 25), and a geometric technique was used to measure serial left ventricular end-diastolic volume. Left ventricular end-diastolic volume for the entire group increased significantly (p less than 0.01) from 153 +/- 30 ml at baseline to 172 +/- 45 ml (at 11 days) to 220 +/- 63 ml (at 10.5 months). Twenty of 36 patients showed greater than 20% increase in left ventricular end-diastolic volume (dilation) with time. This appeared early in seven patients, occurred remote from infarction in seven others and showed a progressive pattern in six.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Diastolic function in patients with aortic stenosis: influence of left ventricular load reduction.

Pressure overload hypertrophy of the left ventricle due to aortic stenosis is associated with abnormalities of left ventricular isovolumic relaxation and early diastolic filling. The relative contribution of the hemodynamic load on the left ventricle to the impairment of diastolic function observed in this disorder remains poorly understood. To study this relation, the vasodilator nitroprusside was administered to eight patients with aortic stenosis and normal systolic function. The effect of a short-term reduction in left ventricular preload and afterload on left ventricular isovolumic relaxation and early diastolic filling was assessed by analysis of simultaneous micromanometer left ventricular pressure and radionuclide angiographic volume measurements. At baseline, left ventricular systolic and end-diastolic pressures were markedly elevated, and associated with prolongation of the time constant of left ventricular relaxation and depression of the left ventricular peak filling rate. Infusion of nitroprusside resulted in reduction of left ventricular systolic (204 +/- 31 to 176 +/- 31 mm Hg, p less than 0.05) and end-diastolic (31 +/- 8 to 18 +/- 6 mm Hg, p less than 0.05) pressures, with no associated improvement in time constant of left ventricular pressure decay (T) (68 +/- 25 to 80 +/- 37 ms, p = NS), T 1/2 (34 +/- 8 to 34 +/- 14 ms, p = NS), left ventricular peak filling rate (2.3 +/- 0.5 to 2.3 +/- 0.8 end-diastolic volume/s, p = NS) or time to left ventricular peak filling rate (150 +/- 50 to 144 +/- 37 ms, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Pulmonary perfusion after rt-PA therapy for acute embolism: early improvement assessed with segmental perfusion scanning.

To determine if pulmonary perfusion was improved in acute pulmonary embolism after therapy with recombinant human tissue-type plasminogen activator (rt-PA), lung scans were obtained before and a mean of 22 hours after therapy in 19 patients. The posttherapy lung scans were compared with baseline, pretherapy scans with use of two semiquantitative methods--an anteroposterior view method, similar to that used in the Urokinase Pulmonary Embolism Trial, and a segmental method that emphasized pulmonary anatomy. There was an improvement in the defect score from 0.35 to 0.14 (P less than .01) when the anteroposterior view method was used and from 0.37 to 0.16 (P less than .01) when the segmental method was used. These encouraging results in the early posttherapy period suggest that rt-PA is especially effective in improving regional perfusion after pulmonary embolism and that a larger controlled trial of therapy with rt-PA for acute pulmonary embolism should be performed. Scoring lung scans with a segmental method is feasible and appropriate for present-day lung scan technique and should be considered in future studies.

Adult↗
PubMed1988

Depression of systolic and diastolic myocardial reserve during atrial pacing tachycardia in patients with dilated cardiomyopathy.

Previous reports have shown that increases in heart rate may result in enhanced left ventricular (LV) systolic and diastolic performance. To assess whether this phenomenon occurs in the presence of depressed LV function, the effects of pacing on LV pressure and volume were compared in seven patients with dilated cardiomyopathy (LV ejection fraction 0.19 +/- 0.11) and six patients with no or minimal coronary artery disease (LV ejection fraction 0.69 +/- 0.11). Patients with normal LV function demonstrated significant increases in LV peak-positive dP/dt, LV end-systolic pressure-volume ratio, LV peak filling rate, and a progressive leftward and downward shift of their pressure-volume diagrams, compatible with increased contractility and distensibility in response to pacing tachycardia. There was no change in LV peak-negative dP/dt or tau. Patients with dilated cardiomyopathy, in contrast, demonstrated no increase in either LV peak-positive dP/dt or the end-systolic pressure-volume ratio, and absence of a progressive leftward shift of their pressure-volume diagrams. Moreover, cardiomyopathy patients demonstrated no increase in LV peak-negative dP/dt or LV peak filling rate and a blunted downward shift of the diastolic limb of their pressure-volume diagrams. Tau, as determined from a derivative method, became abbreviated although never reaching control values. We conclude that patients with dilated cardiomyopathy may demonstrate little or no significant enhancement in systolic and diastolic function during atrial pacing tachycardia, suggesting a depression of both inotropic and lusitropic reserve.

Cardiac Output↗
PubMed1988

Noninvasive external cardiac pacing for thallium-201 scintigraphy.

Improvements in noninvasive external cardiac pacing have led to a technique with reliable electrical capture and tolerable patient discomfort. To assess the use of this modality of pacing in combination with thallium scintigraphy as a noninvasive pacing stress test, we applied simultaneous noninvasive cardiac pacing, hemodynamic monitoring, and thallium-201 scintigraphy in 14 patients undergoing cardiac catheterization for chest pain syndromes. Two patients had normal coronary arteries, while the remaining 12 had significant coronary artery disease. Thallium scintigraphic responses to pacing were compared to routine exercise thallium stress testing in nine of these 14 patients. All patients were noninvasively paced to more than 85% of the age-predicted maximum heart rate. Twelve patients demonstrated reversible thallium defects, which corresponded in 11 cases to significant lesions seen on coronary angiography. Of nine patients who underwent both pacing and exercise thallium stress tests, comparable maximal rate-pressure products were achieved. Moreover, thallium imaging at peak pacing and during delayed views did not differ significantly from exercise thallium scintigraphy. A limiting factor associated with the technique was local patient discomfort, which occurred to some degree in all patients. We conclude that noninvasive external cardiac pacing together with thallium scintigraphy is capable of detecting significant coronary artery disease and may be comparable to routine exercise thallium stress testing. This new modality of stress testing could be useful in patients unable to undergo the exercise required for standard exercise tolerance testing, particularly if improvements in the technology can be found to reduce further the local discomfort.

Cardiac Catheterization↗
PubMed1987

Balloon dilation of mitral stenosis in adult patients: postmortem and percutaneous mitral valvuloplasty studies.

Preliminary reports have documented the utility of percutaneous balloon valvuloplasty of the mitral valve in adult patients with mitral stenosis, but the mechanism of successful valve dilation and the effect of mitral valvuloplasty on cardiac performance have not been studied in detail. Accordingly, mitral valvuloplasty was performed in five postmortem specimens and in 18 adult patients with rheumatic mitral stenosis, using either one (25 mm) or two (18 and 20 mm) dilation balloons. Postmortem balloon dilation resulted in increased valve orifice area in all five postmortem specimens, secondary to separation of fused commissures and fracture of nodular calcium within the mitral leaflets. In no case did balloon dilation result in tearing of valve leaflets, disruption of the mitral ring or liberation of potentially embolic debris. Percutaneous mitral valvuloplasty in 18 patients with severe mitral stenosis (including 9 with a heavily calcified valve) resulted in an increase in cardiac output (4.3 +/- 1.1 to 5.1 +/- 1.5 liters/min, p less than 0.01) and mitral valve area (0.9 +/- 0.2 to 1.6 +/- 0.4 cm2, p less than 0.0001), and a decrease in mean mitral pressure gradient (15 +/- 5 to 9 +/- 4 mm Hg, p less than 0.0001), pulmonary capillary wedge pressure (23 +/- 7 to 18 +/- 7 mm Hg, p less than 0.0001) and mean pulmonary artery pressure (36 +/- 12 to 33 +/- 12 mm Hg, p less than 0.01). Left ventriculography before and after valvuloplasty in 14 of the 18 patients showed a mild (less than or equal to 1+) increase in mitral regurgitation in five patients and no change in the remainder.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Intracoronary thallium-201 scintigraphy after thrombolytic therapy for acute myocardial infarction compared with 10 and 100 day intravenous thallium-201 scintigraphy.

Thallium-201 imaging has been utilized to estimate myocardial salvage after thrombolytic therapy for acute myocardial infarction. However, results from recent animal studies have suggested that as a result of reactive hyperemia and delayed necrosis, thallium-201 imaging may overestimate myocardial salvage. To determine whether early overestimation of salvage occurs in humans, intracoronary thallium-201 scans 1 hour after thrombolytic therapy were compared with intravenous thallium-201 scans obtained approximately 10 and 100 days after myocardial infarction in 29 patients. In 10 patients with angiographic evidence of coronary reperfusion, immediate improvement in thallium defects and no interim clinical events, there was no change in imaging in the follow-up studies. Of nine patients with coronary reperfusion but no initial improvement of perfusion defects, none showed worsening of defects in the follow-up images. Six of these patients demonstrated subsequent improvement at either 10 or 100 days after infarction. Seven of 10 patients with neither early evidence of reperfusion nor improvement in perfusion defects had improvement of infarct-related perfusion defects, and none showed worsening. In conclusion, serial scanning at 10 and 100 days after infarction in patients with no subsequent clinical events showed no worsening of the perfusion image compared with images obtained in acute studies. Therefore, there is no evidence that thallium-201 imaging performed early in patients with acute myocardial infarction overestimates improvement.

Acute Disease↗
PubMed1987

Supine versus upright anterior images: comparison in T1-201 myocardial scintigraphy.

In patients undergoing exercise thallium-201 myocardial scintigraphy, activity in the inferior wall on anterior images may appear diminished when the standard supine view is used, but normal when the view is acquired with the patient upright. To determine the clinical significance of this observation, the distribution of thallium-201 activity was semiquantitatively assessed in supine and upright anterior images obtained immediately after exercise in 93 patients (65 men, 28 women). The presence of inferior wall and coronary artery disease was established with coronary angiography or from documentation of previous myocardial infarction. Supine and upright images were compared with use of receiver operating characteristic curves. In male patients diagnostic accuracy for identification of both inferior wall and coronary artery disease was improved through the use of the upright anterior image. In women, there was no significant difference in reader performance with upright and supine images. Upright anterior images should be routinely obtained in men in order to reduce the frequency of false-positive identification of inferior wall defects.

Adult↗
PubMed1987

Assessment of left ventricular and aortic valve function after aortic balloon valvuloplasty in adult patients with critical aortic stenosis.

Preliminary reports have documented the utility of balloon aortic valvuloplasty as a palliative treatment for high-risk patients with critical aortic stenosis, but the effect of this procedure on cardiac performance has not been studied in detail. Accordingly, 32 patients (mean age 79 years) with long-standing, calcific aortic stenosis were treated at the time of cardiac catheterization with balloon dilatation of the aortic valve, and serial changes in left ventricular and valvular function were followed before and after valvuloplasty by radionuclide ventriculography, determination of systolic time intervals, and Doppler echocardiography. Prevalvuloplasty examination revealed heavily calcified aortic valves in all patients, a mean peak-to-peak aortic valve gradient of 77 +/- 27 mm Hg, a mean Fick cardiac output of 4.6 +/- 1.4 liters/min, and a mean calculated aortic valve area of 0.6 +/- 0.2 cm2. Subsequent balloon dilatation with 12 to 23 mm valvuloplasty balloons resulted in a fall in aortic valve gradient to 39 +/- 15 mm Hg, an increase in cardiac output to 5.2 +/- 1.8 liters/min, and an increase in calculated aortic valve area to 0.9 +/- 0.3 cm2. Individual hemodynamic responses varied considerably, with some patients showing major increases in valve area, while others demonstrated only small increases. In no case was balloon dilatation accompanied by evidence of embolic phenomena. Supravalvular aortography obtained in 13 patients demonstrated no or a mild (less than or equal to 1+) increase in aortic insufficiency. Serial radionuclide ventriculography in patients with a depressed left ventricular ejection fraction (i.e., that less than or equal to 55%) revealed a small increase in ejection fraction from 40 +/- 13% to 46 +/- 12% (p less than .03). In addition, for the study group as a whole there was a decrease in left ventricular end-diastolic volume index (113 +/- 38 to 101 +/- 37 ml/m2, p less than .003), a fall in stroke-volume ratio (1.49 +/- 0.44 to 1.35 +/- 0.33, p less than .04), and no immediate change in left ventricular peak filling rate (2.05 +/- 0.77 to 2.21 +/- 0.65 end-diastolic counts/sec, p = NS). Serial M mode echocardiography and phonocardiography showed an increase in aortic valve excursion (0.5 +/- 0.2 to 0.8 +/- 0.2 cm, p less than .001), a decrease in time to one-half carotid upstroke (80 +/- 30 to 60 +/- 10 msec, p less than .001), and a small decrease in left ventricular ejection time (0.44 +/- 0.03 to 0.42 +/- 0.02 sec, p less than .001).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗