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Biomedical subjects

J L Fleg

Publications and source records attributed to J L Fleg.

At least 19 recordsLinked to original sources
PubMed1992

Long-term prognostic significance of ambulatory electrocardiographic findings in apparently healthy subjects greater than or equal to 60 years of age.

To determine the long-term prognostic significance of frequent or complex ectopic beats and ST-segment changes on 24-hour ambulatory electrocardiogram (ECG) in apparently healthy older subjects, 98 volunteers were followed up from the Baltimore Longitudinal Study of Aging who were 60 to 85 years old and free of cardiac disease by history, physical examination and maximal treadmill testing at the time of ambulatory ECG between 1978 and 1980. Over a mean follow-up period of 10 years, coronary events developed in 14 subjects: angina pectoris in 7, nonfatal myocardial infarction in 3 and sudden cardiac death in 4. The incidence of coronary events did not differ significantly between subjects who developed the following arrhythmias and those who did not, respectively: greater than or equal to 30 supraventricular ectopic beats in any hour, 18 vs 13%; greater than or equal to 100 supraventricular ectopic beats in 24 hours, 20 vs 12%; paroxysmal atrial tachycardia, 15 vs 14%; greater than or equal to 30 ventricular ectopic complexes (VECs) in any hour, 17 vs 14%; greater than or equal to 100 VECs in 24 hours, 18 vs 14%; or repetitive VECs, 20 vs 13%. The mean 24-hour heart rate (75 +/- 8 vs 72 +/- 9 beats/min) as well as the maximal (116 +/- 20 vs 111 +/- 18 beats/min) and minimal (51 +/- 6 vs 53 +/- 7 beats/min) heart rate also did not differ between the coronary event and non-event groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Prevalence and prognostic significance of exercise-induced silent myocardial ischemia in apparently healthy subjects.

The addition of thallium-201 (201Tl) scintigraphy to traditional exercise electrocardiography (ECG) was assessed to determine whether the combination was a more accurate predictor of future coronary events than exercise ECG alone in an apparently healthy population. There were 407 participants enrolled in the Baltimore Longitudinal Study of Aging. The participants, who had no clinical or resting ECG evidence of coronary artery disease, underwent 201Tl scintigraphy immediately following maximal treadmill exercise. Four subsets of subjects were derived: (1) negative ECG and negative 201Tl; (2) positive ECG and negative 201Tl; (3) negative ECT and positive 201Tl; (4) positive ECG and positive 201Tl. A total of 66 individuals (16%) had positive ECGs and 55 (14%) had positive 201Tl scans. Concordant positive results in both tests were seen in 23 subjects (6%), with a 7-fold increase in prevalence from ages 40-59 years to greater than 80 years. Over a mean follow-up of 4.6 years, cardiac events (angina pectoris, myocardial infarction, or cardiac death) occurred in 40 of 407 volunteers (9.8%). Analysis revealed a 48% incidence of cardiac events in the subset with concordant abnormal ECG and 201Tl test results versus an event rate of 3-12% for the other 3 groups (p less than 0.001). By proportional hazards analysis, age, hypertension, exercise duration, and a concordant positive ECG and 201Tl scan were independent predictors of future coronary events. A concordant abnormal ECG and 201Tl response imparted a 3.6-fold relative event risk. Although not practical for screening the general population, combined exercise ECG and 201Tl scintigraphy warrants further investigation as a diagnostic strategy in high-risk subsets with additional coronary risk factors.

Adult↗
PubMed1992

Age-related decline in left ventricular filling at rest and exercise.

To determine whether the age-associated decline in resting left ventricular diastolic filling persists during aerobic exercise, rest and bicycle exercise filling indexes were measured from gated radionuclide blood pool scans in 88 healthy men aged 22-82 yr. To evaluate the effect of physical conditioning status on these age-related changes, a subset of the subjects consisted of endurance-trained senior athletes with a maximal O2 consumption of 50.5 +/- 5 compared with 32.6 +/- 7 ml.kg-1 x min-1 in age-matched controls. The contribution of beta-adrenergic stimulation to exercise-induced changes in filling was also evaluated by the administration of intravenous propranolol to another subset before testing. Peak filling rate increased progressively at all ages with increasing exercise work loads. The peak filling rates at rest, 50% maximal exercise, and maximum exercise inversely correlated with age (r = -0.64, -0.53, -0.64, respectively). Rest and exercise filling indexes in senior athletes were similar to those of sedentary older subjects. Propranolol decreased exercise peak filling rates in young (37.2 +/- 7.5 yr) but not in older (62.1 +/- 6 yr) subjects. Therefore, filling rates increase with exercise in both young and older healthy men, but age differences persist at comparable relative work loads. This decline is not secondary to a decline in physical conditioning status but appears to be related to a decrease in beta-adrenergic responsiveness in older individuals.

Adrenergic beta-Antagonists↗
PubMed1991

Frequency and importance of postprandial blood pressure reduction in elderly nursing-home patients.

OBJECTIVE: To determine the frequency and importance of postprandial reductions in systolic blood pressure in debilitated, elderly patients receiving nursing home care. DESIGN: Cohort study. SETTING: Community-based, university-affiliated, teaching nursing home. PATIENTS: A total of 113 volunteer nursing-home residents with a mean (+/- SD) age of 78 +/- 9 years; seven residents who refused the test meal served as controls. INTERVENTION: Participants had sequential blood pressure measurements for 90 minutes after the administration of a standardized meal. MEASUREMENTS AND MAIN RESULTS: Of 113 patients, 109 (96%) showed a postprandial reduction in systolic blood pressure (mean reduction, 17.9 +/- 15.5 mm Hg) within 75 minutes; 41 patients (36%) had a reduction in systolic blood pressure of more than 20 mm Hg. Twelve patients (11%) had a reduction in systolic blood pressure to less than 100 mm Hg (mean systolic blood pressure, 88 +/- 6.4 mm Hg); two of these patients became acutely symptomatic. Multiple regression analysis showed that higher premeal systolic blood pressure, a history of syncope, treatment with vasodilators, and dependent posture of the lower extremities during the postprandial period were all associated with a more severe postprandial decline in systolic blood pressure. Systolic blood pressure in noneating control subjects did not change during the same observation period. No significant differences in the mean systolic blood pressure nadir were found between the 14 patients who died during the follow-up period (mean follow-up, 6.1 +/- 3.8 months) and those who survived. CONCLUSION: Postprandial reductions in systolic blood pressure among elderly nursing-home patients are common, often large, and potentially symptomatic, but they do not generally presage subsequent intermediate-term mortality.

Aged↗
PubMed1991

Effect of maintenance digoxin therapy on aerobic performance and exercise left ventricular function in mild to moderate heart failure due to coronary artery disease: a randomized, placebo-controlled, crossover trial.

Despite 200 years of use, the ability of digitalis glycosides to improve exercise capacity in patients with congestive heart failure remains controversial, partly because of imprecise end points and suboptimal study design. Therefore, this question was examined in 10 ambulatory patients (8 men and 2 women) aged 46 to 70 years (mean 57.8) in sinus rhythm with mild to moderate chronic stable congestive heart failure due to coronary artery disease and systolic left ventricular dysfunction (ejection fraction 32 +/- 12). All underwent maximal treadmill exercise with respiratory gas analysis and upright cycle ergometry with gated radionuclide angiography after 4 weeks of digoxin or placebo therapy, administered in a randomized double-blind crossover protocol. Neither treadmill exercise duration (7.7 +/- 2.3 versus 7.3 +/- 2.7 min) nor peak oxygen consumption (18.7 +/- 3.7 versus 18.4 +/- 5.4 ml/kg per min) differed between digoxin and placebo regimens. However, the change in peak oxygen consumption induced by digoxin was inversely related to the peak oxygen consumption during placebo therapy (r = -0.64, p less than 0.05). At maximal treadmill effort, heart rate (138 +/- 16 versus 141 +/- 21 beats/min), oxygen pulse (10.3 +/- 2.1 versus 9.9 +/- 2.2 ml/beat), ventilation (40.3 +/- 10.6 versus 42.0 +/- 10.8 liters/min) and ventilatory equivalent (29.4 +/- 4.8 versus 31.5 +/- 6.8) did not differ between digoxin and placebo treatment, although systolic blood pressure was higher during digoxin therapy (163.0 +/- 23.1 versus 153.2 +/- 25.3 mm Hg, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Effect of age of entry to a longitudinal study on cross-sectional determination of cardiovascular disease.

Cross-sectional analysis from longitudinal studies for a specific age can include subjects who entered the study at different ages (i.e. younger individuals followed to the age of interest, and those who entered at the age of interest). This represents a potential source of bias, since the state of health at a given age may vary based on age at entry. We investigated such bias as it affected the prevalence of cardiovascular diagnoses in men from the Baltimore Longitudinal Study of Aging. Subjects who entered the study in either their 60's, 70's or 80's (New subjects) were compared to individuals who entered the study at an age at least 10 years younger and were followed into these same age decades (Continuing subjects). No differences were found between New and Continuing subjects for coronary heart or cerebrovascular diseases, but were present for hypertension. The greater prevalence of hypertension in Continuing subjects appeared to be of minor clinical importance because other diagnostic differences were absent. The study found evidence for potential selection bias based on age at entry, but the consequence of the bias appeared to be slight.

Age Factors↗
PubMed1991

Effect of postural stress on left ventricular performance using the continuous-wave Doppler technique.

To evaluate the effect of postural shifts on continuous-wave Doppler indices of left ventricular performance in normal man, we recorded Doppler signals suprasternally in 69 healthy volunteers, ranging in age from 20 to 86 years, in the supine position and 2 min after assumption of sitting and standing postures. All indices decreased progressively with increasing orthostasis: peak acceleration (PKA): 15.6 +/- 4.5 m/s2 to 14.0 +/- 4.0 m/s2 to 13.6 +/- 4.6 m/s2; peak velocity (PKV): 0.64 +/- 0.18 m/s to 0.58 +/- 0.17 m/s to 0.56 +/- 0.17 m/s; stroke distance (SD): 11.4 +/- 3.7 cm to 9.8 +/- 3.4 cm to 8.0 +/- 2.8 cm; SD x heart rate (VIH): 717 +/- 272 cm to 655 +/- 268 cm to 572 +/- 217 cm, from supine to sitting to standing, respectively (p less than 0.001). In contrast heart rate increased modestly from 62.4 +/- 10.0 bpm supine, to 66.9 +/- 12.4 bpm sitting, to 71.3 +/- 9.9 bpm standing (p less than .001). Similar postural changes in Doppler variables were seen in all three age groups (20 to 44 years; 45 to 64 years; and 65 to 86 years). Thus, orthostasis in normal subjects is accompanied by a reduction in all continuous-wave Doppler indices of left ventricular performance, regardless of age.

Adult↗
PubMed1991

Age as independent determinant of glucose tolerance.

It has been proposed that the decline in glucose tolerance with age is not a primary aging effect but is secondary to a combination of other age-associated characteristics, i.e., disease, medication, obesity, central and upper-body fat deposition, and inactivity. To test this hypothesis, we first eliminated from analysis the Baltimore Longitudinal Study of Aging participants with identifiable diseases or medications known to influence glucose tolerance. Seven hundred forty-three men and women, aged 17-92 yr, remained for analysis. As indices of fatness, body mass index and percent body fat were determined. As indices of body fat distribution, waist-hip ratio and subscapular triceps skin-fold ratio were calculated. As indices of fitness, physical activity level, determined by detailed questionnaire, and maximum 02 consumption were calculated. We tested whether the effect of age on glucose tolerance remains when data were adjusted for fatness, fitness, and fat distribution; 2-h glucose values were 6.61, 6.78, and 7.83 mM for young (17-39 yr), middle-aged (40-59 yr), and old (60-92 yr) men and 6.22, 6.22, and 7.28 mM for the three groups of women, respectively. The differences between the young and middle-aged groups were not significant, but the old groups had significantly higher values than young or middle-aged groups. Fatness, fitness, and fat distribution can account for the decline in glucose tolerance from the young adult to the middle-aged years. However, age remains a significant determinant of the further decline in glucose tolerance of healthy old subjects.

Adipose Tissue↗
PubMed1991

Angina pectoris in the elderly.

Although the ability to document angina pectoris in the elderly patient may be compromised by atypical symptoms, limited activity levels, and blunted recall, anginal symptoms convey a similar adverse prognosis regardless of age. In general, the therapeutic approach to the older anginal patient should be dictated more by achievement of symptomatic relief than by considerations of long-term survival. No randomized trial exists to guide the decision of medical versus coronary artery bypass surgery versus angioplasty in the older patient with coronary artery disease; symptomatic relief, however, appears greater after revascularization procedures.

Aged↗
PubMed1990

Age-associated changes in the components of atrioventricular conduction in apparently healthy volunteers.

The mechanism for the prolongation of P-R interval associated with advancing age is undefined. Using a high-resolution ECG (Marquette MAC-1) to signal average 512 cardiac cycles, we examined 185 healthy volunteers aged 20-83 years from the Baltimore Longitudinal Study of Aging with normal rest and exercise ECGs and a resting P-R interval less than 210 ms. Among the 161 subjects with visible His bundle activity, P-R interval increased with age (p less than .001). This increase was due entirely to prolongation of the interval between the P wave onset and His bundle potential, i.e., the P-H interval, (p less than .001) with no age-associated change in the H-V interval, p = NS. The P-H interval prolongation with age was localized to the P-R segment proximal to His bundle activation (p less than .001). In a separate group of 7 asymptomatic older men (mean age = 71 yr), with first-degree atrioventricular (A-V) block on standard ECG (mean PR = 238 +/- 14 ms), the P-H interval (193 +/- 21, vs 136 +/- 18 ms, p less than .001) and proximal P-R segment (82 +/- 19) vs 33 +/- 15 ms, p less than .001) but not the H-V interval (45 +/- 11 vs 40 +/- 9 ms, p = NS) were longer than in 25 age-matched men without A-V block. Thus, the modest age-associated prolongation of the P-R interval is localized to the proximal P-R segment, probably reflecting delay within the atrioventricular junction. A similar but more striking delay in the proximal P-R segment is responsible for first degree A-V block in apparently healthy older men.

Adult↗
PubMed1990

The age-associated decline in glomerular filtration in healthy normotensive volunteers. Lack of relationship to cardiovascular performance.

Whether the well-documented age-associated decline in the glomerular filtration rate, manifest as a decline in creatinine clearance, is secondary to an age-related change in cardiovascular performance is at present unknown. To answer this question, we measured arterial blood pressure, 24-hour creatinine clearance, and cardiac output determined from gated cardiac blood pool scans in the sitting position in healthy normotensive men (n = 75) and women (n = 42) (ages 25 to 82 years), from the Baltimore Longitudinal Study on Aging. These subjects were selected for the absence of cardiovascular disease, renal disease, and confounding medications. By linear regression analysis, creatinine clearance, expressed in mL/min/m2, declined cross-sectionally with age (creatinine clearance = 90 -0.33[age], r = .31, P less than .001), whereas systolic blood pressure in mm Hg increased with age (systolic blood pressure = 111 + 0.27[age], r = .30, P less than .001); cardiac output in L/min/m2 did not vary with age (r = .03, P = .74). In stepwise multiple regression analysis with age, cardiac index, and systolic blood pressure as independent variables and creatinine clearance as the dependent variable, only age was a significant predictor of creatinine clearance. (F = 11.31, DF + 116, r = .30, P less than .001). Thus, the age-associated decline in creatinine clearance is not modulated by changes in cardiac index or systolic blood pressure in healthy normotensive subjects.

Adult↗
PubMed1990

Interaction between left ventricular end-diastolic and end-systolic volumes in normal humans.

The extent to which the end-systolic volume (ESV) "follows" the end-diastolic volume (EDV) when the latter changes in response to various perturbations is a major determinant of the cardiac ejection fraction (EF) and has not been studied in humans. We measured EDV, ESV, and EF, determined by gated blood pool scans, during a change in posture from the supine to the upright seated position and during graded upright bicycle exercise. The experimental group consisted of 119 healthy individuals (79 males and 40 females) ranging in age from 21 to 81 yr and in physical-conditioning status (75-225 W maximum work load); rigorous screening excluded cardiac disease. Multiple regression analysis showed that the change in ESV (delta ESV) during a postural shift or during graded exercise was highly statistically correlated with the change in EDV (delta EDV) that occurred (r2 ranged from 0.34 to 0.49, correlation is positive) regardless of age, sex, or exercise work load. The correlation of delta ESV with delta EDV observed in this large sample, heterogeneous with respect to age, sex, and physical fitness, was also present in additional 31 subjects who exercised during beta-adrenergic blockade (propranolol 0.15 mg/kg). The delta EF with posture change and exercise in all subjects under all conditions was highly and inversely correlated with the delta ESV (r2 ranged from 0.38 to 0.81). Thus the delta ESV during the circulatory adaptive response to orthostatic and exercise stresses in humans is related to the delta EDV, and this relationship modulates the delta EF in response to these stresses.

Adult↗
PubMed1990

Can serial exercise testing improve the prediction of coronary events in asymptomatic individuals?

An abnormal ST segment response to treadmill exercise has a low predictive value for future coronary events (angina pectoris, nonfatal myocardial infarction, or cardiac death) in apparently healthy individuals. To determine whether the conversion from a normal to an abnormal ST segment response might identify individuals at high risk for a future coronary event, we analyzed the results of serial exercise tests performed at 2-4-year intervals in 726 male and female volunteers, aged 22-84 years (mean, 55.1 years), from the Baltimore Longitudinal Study of Aging (BLSA). All subjects were free of cardiovascular disease at entry by history, physical examination, and resting 12-lead electrocardiogram. Over a mean overall follow-up of 7.4 years, coronary events occurred in 34 of 178 (19.1%) of those with an abnormal ST response to exercise versus 30 of 548 (5.5%) in those with a normal response (p = 0.001). Angina pectoris was the most common presenting coronary event regardless of ST segment exercise response. Among individuals with an abnormal ST segment response, the incidence of events was virtually identical between those with an initially abnormal response (group 1) and those who converted from a normal to an abnormal response (group 2), 19.8% versus 18.5%. After adjustment for standard coronary risk factors by proportional hazards regression analysis, the risk of a coronary event relative to subjects with persistently normal ST segment responses (group 3) remained nearly identical in the two groups, 2.72 in group 1 (p less than 0.003) and 2.80 in group 2 (p less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Prevalence and prognostic significance of exercise-induced silent myocardial ischemia detected by thallium scintigraphy and electrocardiography in asymptomatic volunteers.

Although a silent ischemic electrocardiographic response to treadmill exercise in clinically healthy populations is associated with an increased likelihood of future coronary events (i.e., angina pectoris, myocardial infarction, or cardiac death), such a response has a low predictive value for future events because of the low prevalence of disease in asymptomatic populations. To examine whether detection of reduced regional perfusion by thallium scintigraphy improved the predictive value of exercise-induced ST segment depression, we performed maximal treadmill exercise electrocardiography (ECG) and thallium scintigraphy (201Tl) in 407 asymptomatic volunteers 40-96 years of age (mean = 60) from the Baltimore Longitudinal Study on Aging. The prevalence of exercise-induced silent ischemia, defined by concordant ST segment depression and a thallium perfusion defect, increased more than sevenfold from 2% in the fifth and sixth decades to 15% in the ninth decade. Over a mean follow-up period of 4.6 years, cardiac events developed in 9.8% of subjects and consisted of 20 cases of new angina pectoris, 13 myocardial infarctions, and seven deaths. Events occurred in 7% of individuals with both negative 201Tl and ECG, 8% of those with either test positive, and 48% of those in whom both tests were positive (p less than 0.001). By proportional hazards analysis, age, hypertension, exercise duration, and a concordant positive ECG and 201Tl result were independent predictors of coronary events. Furthermore, those with positive ECG and 201Tl had a 3.6-fold relative risk for subsequent coronary events, independent of conventional risk factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Prevalence and long-term significance of exercise-induced frequent or repetitive ventricular ectopic beats in apparently healthy volunteers.

Frequent or repetitive exercise-induced ventricular ectopic beats are often considered a marker for serious cardiac disease or sudden death, or both. However, the prognostic value of these arrhythmias in an unreferred asymptomatic community-dwelling population over a broad age range is unknown. Of 1,160 subjects aged 21 to 96 years who underwent maximal exercise treadmill testing an average of 2.4 times, 80 (6.9%) developed frequent (greater than or equal to 10% of beats in any 1 min) or repetitive (greater than or equal to 3 beats in a row) ventricular ectopic beats on at least one test. These 80 individuals were significantly older than the group without such arrhythmia (63.8 +/- 12.5 versus 50.0 +/- 16.1 years, p less than 0.0001). A striking age-related increase in the prevalence of frequent or repetitive exercise-induced ventricular ectopic beats was seen in men (p less than 0.0001) but not in women. The prevalence of electrocardiographic abnormalities at rest, exercise-induced ST segment depression and thallium perfusion defects, duration of treadmill exercise, maximal heart rate, systolic blood pressure and rate-pressure product did not differ between these 80 study subjects with frequent exercise-induced ventricular ectopic beats and a control group matched for age and gender. Furthermore, the incidence of cardiac events (angina pectoris, nonfatal myocardial infarction, cardiac syncope or cardiac death) (10% versus 12.5%) as well as noncardiac mortality (each 7.5%) was found to be similar for the study and control groups, respectively, over a mean follow-up period of 5.6 years. No study subjects required antiarrhythmic drugs over this time interval.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Physician utilization of laboratory procedures to monitor outpatients with congestive heart failure.

Little is known about how different types of physicians use laboratory procedures in the management of outpatients with congestive heart failure. We therefore analyzed data from a national survey of randomly selected general practitioners, internists, and cardiologists to assess their management of outpatients with New York Heart Association class II congestive heart failure. Most of the 2704 respondents (90%) scheduled office visits between two and four months apart. Body weight, serum electrolytes, and chest roentgenograms were followed regularly by 98% or more of respondents, at median intervals of one to two months, three to five months, and 12 to 17 months, respectively. Serum digoxin levels in patients taking digoxin were followed by 90% of respondents at a median interval of 12 months. Echocardiography, radionuclide ventriculography, and exercise testing were used by fewer respondents (81%, 61%, and 61%, respectively), each at a median interval of 18 months or longer. Cardiologists were significantly more likely to follow patients using either echocardiography, radionuclide ventriculography, or exercise testing. The estimated yearly cost of following a class II congestive heart failure outpatient varied nearly fourfold from the lowest quartile of physicians ($303) to the highest ($1167). Cardiologists were disproportionately represented among the high-cost users. In addition, physicians who were younger or who practiced in an urban setting were significantly more likely to be high-cost users. Thus, simple laboratory tests were used most frequently to follow patients with heart failure, but differences in use of more expensive tests led to large differences in cost. Test use for similar patients is affected by characteristics of both the physician and practice setting.

Ambulatory Care↗