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Biomedical subjects

J L Fleg

Publications and source records attributed to J L Fleg.

108 records · Page 6Linked to original sources
PubMed1985

Age-related augmentation of plasma catecholamines during dynamic exercise in healthy males.

Although plasma norepinephrine (NE) increases with age in response to a variety of submaximal adrenergic stimuli, the effect of age on plasma catecholamine levels during maximal aerobic effort and during submaximal work at a fixed percent of peak O2 consumption (VO2) is unknown. We therefore measured NE, epinephrine (E), and VO2 at rest and during graded maximal treadmill exercise in 24 healthy male volunteers (ages 22-77 yr) from the Baltimore Longitudinal Study of Aging who were rigorously screened to exclude the presence of cardiovascular disease. At rest neither heart rate (HR) nor VO2 were age related. Resting NE (pg/ml) was not age related, but resting E (pg/ml) was higher in male subjects 68-77 yr old (group III) than in those aged 22-37 (group I) or 44-55 yr (group II), P less than 0.01. Maximal HR (beats/min) showed a strong inverse relationship to age (203.5 - 0.65 age, r = -0.80, P less than 0.001). Peak VO2 in milliliters per kilogram total body weight per minute decreased with age (47.7 - 0.23 age, r = -0.71, P less than 0.001). At maximal effort both NE (P less than 0.01) and E (P less than 0.05) were higher in group III than in either of the younger groups. At submaximal work levels NE and E also increased with age, and when normalized for relative effort at loads between 45 and 80% of peak VO2 both NE and E were higher in the group III male subjects, although statistical significance was reached for NE (P less than 0.01) but not for E (P = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Prevalence and prognosis of exercise-induced nonsustained ventricular tachycardia in apparently healthy volunteers.

Although exercise-induced ventricular tachycardia (VT), whether sustained or nonsustained, is usually associated with significant organic heart disease, its prevalence, associated characteristics and prognostic significance in an asymptomatic, unreferred community-dwelling population are unknown. Therefore, the prevalence of VT associated with maximal treadmill exercise was assessed in 597 male and 325 female volunteers, aged 21 to 96 years (mean +/- standard deviation 54 +/- 16), from the Baltimore Longitudinal Study on Aging who were without apparent heart disease. Ten subjects, 7 men and 3 women, with exercise-induced VT were identified, representing 1.1% of those tested; only 1 was younger than 65 years. All episodes of VT were asymptomatic and nonsustained. In 9 of 10 subjects, VT developed at or near peak exercise. The longest run of VT was 6 beats; multiple runs of VT were present in 4 subjects. Two subjects had exercise-induced ST-segment depression, but subsequent exercise thallium scintigraphic results were negative in each. Compared with a group of age- and sex-matched control subjects, those with asymptomatic, nonsustained VT displayed no difference in exercise duration, maximal heart rate, or the prevalence of coronary risk factors or exercise-induced ischemia as measured by electrocardiography and thallium scintigraphy. Over a mean follow-up period of 2 years, no subject has developed symptoms of heart disease or experienced syncope or sudden death. Thus, exercise-induced VT in apparently healthy subjects occurs almost exclusively in the elderly, is limited to short, asymptomatic runs of 3 to 6 beats usually near peak exercise, and does not portend increased cardiovascular morbidity or mortality rates over a 2-year period of observation.

Adult↗
PubMed1984

Insensitivity of the electrocardiogram in apical myocardial infarction.

The ability of the standard ECG to identify myocardial infarction (MI) involving primarily the left ventricular (LV) apex is controversial. Therefore, the ECGs of 62 consecutive patients with acute infarction and isolated akinesia or dyskinesia of the LV apex on gated blood pool scintigraphy performed at rest 9 +/- 4 days after MI, were reviewed. The following distribution of Q waves was found: none, 26%; inferior leads only, 23%; anterior leads only, 32%; inferior + 1 or more V leads, 13%; lead I and/or aVL + 1 or more V leads, 6%. Only 12 patients (19%) demonstrated one of the "combination" Q-wave patterns thought to indicate apical infarction. Although the 20 patients with a history of MI did not differ in age or ejection fraction from those with a first MI, the combination of inferior and anterior Q waves was present in 6 of them (30%), vs only 2 of the remaining 42 patients (5%) (p less than 0.02). The 24 patients with apical dyskinesia had a lower ejection fraction (36 +/- 14 vs 48 +/- 12, p less than 0.001), a lower prevalence of isolated inferior Q waves (8 vs 32%, p less than 0.05) and a greater prevalence of isolated anterior Q waves (46 vs 24%, p = 0.09) than those with akinesia. Thus, in patients with recent MI localized to the LV apex on radionuclide ventriculography, pathologic Q waves are commonly confined to the anterior or inferior leads or absent altogether. The insensitivity of the various proposed criteria for the electrocardiographic diagnosis of apical MI emphasizes the value of imaging techniques in detecting this common clinical entity.

Adult↗
PubMed1984

Exercise cardiac output is maintained with advancing age in healthy human subjects: cardiac dilatation and increased stroke volume compensate for a diminished heart rate.

To assess the effect of age on cardiac volumes and function in the absence of overt or occult coronary disease, we performed serial gated blood pool scans at rest and during progressive upright bicycle exercise to exhaustion in 61 participants in the Baltimore Longitudinal Study of Aging. The subjects ranged in age from 25 to 79 years and were free of cardiac disease according to their histories and results of physical, resting and stress electrocardiographic, and stress thallium scintigraphic examinations. Absolute left ventricular volumes were obtained at each workload. There were no age-related changes in cardiac output, end-diastolic or end-systolic volumes, or ejection fraction at rest. During vigorous exercise (125 W), cardiac output was not related to age (cardiac output [1/min] = 16.02 + 0.03 [age]; r = .12, p = .46). However, there was an age-related increase in end-diastolic volume (end-diastolic volume [ml] = 86.30 + 1.48 [age]; r = .47, p = .003) and stroke volume (stroke volume [ml] = 85.52 + 0.80 [age]; r = .37, p = .02), and an age-related decrease in heart rate (heart rate [beats/min] = 184.66 - 0.70 [age]; r = -.50, p = .002). The dependence of the age-related increase in stroke volume on diastolic filling was emphasized by the fact that at this high workload end-systolic volume was higher (end-systolic volume [ml] = 3.09 + 0.65 [age]; r = .45, p = .003) and ejection fraction lower (ejection fraction = 88.48 - 0.18 [age]; r = -.33, p = .04) with increasing age. These findings indicate that although aging does not limit cardiac output per se in healthy community-dwelling subjects, the hemodynamic profile accompanying exercise is altered by age and can be explained by an age-related diminution in the cardiovascular response to beta-adrenergic stimulation.

Adult↗
PubMed1983

Right bundle branch block: long-term prognosis in apparently healthy men.

The long-term cardiac prognosis of 24 clinically healthy men with complete right bundle branch block, identified from the 1,142 men constituting the population of the Baltimore Longitudinal Study on Aging, was assessed over a follow-up period averaging 8.4 years. When compared with a control group matched for age at which right bundle branch block appeared (mean +/- standard deviation 64.0 +/- 13.5 years), men with right bundle branch block showed no difference in the prevalence of antecedent coronary risk factors or obstructive lung disease. The incidence of angina pectoris, myocardial infarction, valvular heart disease, cardiomegaly, congestive heart failure, advanced heart block or cardiac death in these men did not differ from that of the control group over the observation period. Furthermore, at the latest follow-up study, maximal aerobic exercise tolerance and chronotropic response to maximal exercise were not impaired in men with right bundle branch block relative to control men (9.1 +/- 2.2 versus 7.3 +/- 3.0 minutes and 150.3 +/- 23.5 versus 147.7 +/- 20.7 beats/minute, respectively). However, axis deviation leftward of -30 degrees was present in 46% of men with right bundle branch block but in only 15% of control subjects at latest follow-up (probability [p] less than 0.01). Although the PR interval lengthened by 40 ms or more developed in only 6% of control subjects over the observation period, such prolongation occurred in 29% of men with right bundle branch block (p less than 0.05). These results support the concept that right bundle branch block in these asymptomatic men is a manifestation of a primary abnormality of the cardiac conduction system but has no demonstrable adverse effect on long-term cardiac morbidity or mortality.

Aged↗
PubMed1983

Longitudinal chest x-ray changes in normal men.

To determine the changes on chest x-ray attributable to the aging process, we evaluated cardiovascular and pulmonary structures on two standard postero-anterior chest x-rays taken at least 10 years apart (M = 16.9 years) in 67 carefully screened healthy men initially aged 23 to 76 years. The aortic knob diameter increased in 79% of subjects. Although mean cardiothoracic ratio increased overall, only 3% of men developed a cardiothoracic ratio greater than .50, and none exceeded .51. Pulmonary abnormalities on initial chest x-ray consisted mainly of hyperinflation (27%) and increased markings (19%), both of which doubled in prevalence during follow-up. Kerley B lines and enlarged pulmonary arteries were rare initially but increased three- to five-fold. The prevalence of these findings did not differ between smokers and nonsmokers. Based on commonly accepted x-ray criteria, chronic obstructive lung disease was suggested in 15% of the initial films and 21% of the final films despite the absence of clinical or spirometric abnormalities.

Adult↗
PubMed1983

Asystole following treadmill exercise in a man without organic heart disease.

A 52-year-old man without evidence of organic heart disease by clinical and extensive noninvasive examination experienced an 11-s episode of asystole ten minutes after completing a maximal treadmill test. Four years previously, symptomatic sinus bradycardia and hypotension had also followed cessation of treadmill exercise. This case illustrates that vagally mediated complications of treadmill exercise occurring in persons without apparent heart disease may be potentially life-threatening and can be elicited on repeated testing.

Arrhythmias, Cardiac↗
PubMed1982

Is digoxin really important in treatment of compensated heart failure? A placebo-controlled crossover study in patients with sinus rhythm.

To assess the efficacy of digitalis in patients with chronic clinically compensated congestive heart failure and normal sinus rhythm, we performed a double-blind crossover study with digoxin and placebo in 30 consecutive outpatients fulfilling these criteria; serum digoxin levels, clinical symptoms and signs, and objective indexes of cardiac function were monitored. No patient's clinical condition deteriorated during three months of placebo administration. Discontinuation of digoxin resulted in a small increase in echocardiographically determined resting left ventricular end-diastolic dimension (1.8 +/- 0.6 mm, p less than 0.001) and a similar decrease in velocity of circumferential fiber shortening (-0.08 +/- 0.04 circ/sec, p less than 0.05) from the corresponding values of 55.8 +/- 2.3 mm and 0.90 +/- 0.08 circ/sec during digitalis therapy. Resting left ventricular ejection time and pre-ejection period were prolonged by digoxin withdrawal. Maximal exercise capacity was unchanged. No clinical exacerbation of heart failure attributable to digitalis withdrawal occurred over a follow-up period averaging 19 months. The results indicate that long-term digoxin therapy has only a minor effect on cardiac performance that is without apparent clinical importance in a representative population of ambulatory patients treated with cardiac glycosides.

Adult↗
PubMed1982

Cardiac arrhythmias in a healthy elderly population: detection by 24-hour ambulatory electrocardiography.

Twenty-four hour ambulatory electrocardiographic examination was preformed in 98 healthy active subjects, ages 60 to 85 years, who were participants in a longitudinal study on aging. Normal health was confirmed by noninvasive testing, including maximal treadmill exercise (98/98) and thallium scintigraphy (38/98). Our studies indicated that a healthy population of elderly subjects shows a substantial prevalence of supraventricular ectopic beats and ventricular ectopic beats, both isolated and complex. High degree AV block, profound sinus bradycardia, abnormal sinus pauses and sinus arrest are rare in normal elderly subjects.

Aged↗
PubMed1978

99mTc-pyrophosphate imaging in acute pericarditis: a clinical and experimental study.

Fifteen patients with clinical and electrocardiographic features of acute pericarditis underwent myocardial scintigraphy using 99mTc-pyrophosphate. All had normal images. In 5 additional patients with acute pericarditis and evidence of ischemic heart disease, 99mTc-pyrophosphate images showed focal abnormalities in 2 patients and equivocal findings in 2. Serial myocardial radionuclide images were obtained 2 to 18 days after induction of pericarditis in 8 dogs; all images were normal. No stainable tissue calcium was demonstrated histochemically in the pericardium or myocardium of these dogs. Our results suggest that 99mTc-PYP myocardial radionuclide images are normal in acute pericarditis in the absence of ischemic heart disease.

Acute Disease↗
PubMedDate not supplied

Do echocardiographic changes explain the age-associated increase in exercise-induced supraventricular arrhythmias?

Although exercise-induced supraventricular arrhythmias (EISVA) increase with advancing age, it is unclear whether age-associated changes in cardiac structure or function play a major role in this increase. To address this question, we examined the relationship between M-mode echocardiographic variables and EISVA occurring during maximal treadmill exercise in 366 healthy volunteers aged 20 to 90 years from the Baltimore Longitudinal Study of Aging. Simple (i.e., isolated) EISVA were detected in 69 subjects (19%), and complex EISVA (i.e., comprising > 10% of beats in any minute or occurring in runs) in another 29 subjects (8%). Univariate predictors of any EISVA, whether simple or complex, were older age (p < 0.0001), male gender (p < 0.05), greater left atrial size (p < 0.01), left ventricular mass index (p < 0.0001), interventricular septal thickness (p < 0.001), isovolumic relaxation time (p < 0.01), atrial filling fraction (p < 0.01), reduced mitral E-F closure slope (p < 0.001), peak E velocity (p < 0.02), and peak E/A ratio (p < 0.0001). Lesser exercise duration (p < 0.01), lower maximal heart rate (p < 0.0001), and higher peak systolic and diastolic blood pressures (p < 0.001) were also associated with EISVA. However, by multiple logistic regression analysis, age (p < 0.0001) was the only independent predictor of any EISVA. Univariate predictors of complex EISVA were greater age (p < 0.0001), and atrial filling fraction (p < 0.001), diastolic blood pressure (p < 0.05), lesser mitral E-F slope (p < 0.004), exercise duration (p < 0.005) and maximal heart rate (p < 0.01). However, only age (p < 0.0001) independently predicted complex EISVA. Thus, in healthy volunteers undergoing maximal treadmill exercise. EISVA are associated with greater left ventricular wall thickness, reduced early diastolic performance, diminished exercise capacity and elevated exercise blood pressure. However, none of these variables are independent predictors of EISVA over and above the powerful effect of age.

Adult↗
PubMedDate not supplied

Cholesterol as a risk factor for coronary heart disease in elderly men. The Baltimore Longitudinal Study of Aging.

In order to explore the relationship of cholesterol to coronary heart disease (CHD), defined as angina pectoris, myocardial infarction, and sudden coronary death, in older men, a group of 1052 men, participants in the Baltimore Longitudinal Study on Aging, were examined. Subjects were stratified into three age groups, 28 to 64, 65 to 74, and 75 to 97 years old. In all three age groups, cholesterol was a significant risk factor for CHD. In the oldest age group (n = 250), the relationship between cholesterol and risk was linear (P = .003) as opposed to younger age groups where the relationship was exponential. This study extends the age range in which hypercholesterolemia has been shown to be associated with CHD to include the 75- to 97-year range.

Adult↗
PubMedDate not supplied

Stress testing in the elderly.

The ever-increasing number of older patients requiring diagnostic and prognostic assessment for coronary artery disease has necessitated accurate, noninvasive techniques applicable to this age group. Exercise testing, either alone or with radionuclide or echocardiographic imaging, remains a useful tool in elderly patients capable of performing vigorous treadmill or cycle exercise. Fortunately, for the large elderly subset incapable of such exercise, pharmacologic stress testing with dipyridamole, adenosine, or dobutamine offers an excellent alternative. Choosing the most appropriate stress testing modality for a given patient from among the many choices available remains the clinician's challenge.

Adult↗
PubMedDate not supplied

Plasma levels of estradiol, testosterone, and DHEAS do not predict risk of coronary artery disease in men.

Prior studies have reported men with coronary artery disease (CAD) to have elevated plasma levels of estrogens and reduced concentrations of dehydroepiandrosterone (DHEA) or DHEA-sulfate (DHEAS). We investigated whether gonadal steroids or DHEAS are risk factors for CAD in men, using a prospective design, in a well characterized population studied at regular intervals. We studied 46 men (Cardiac group) who developed CAD and 124 men (Control group) who remained free of CAD (mean follow-up, 9.5 years). We measured testosterone (T), estradiol (E2), and DHEAS, as well as plasma binding of T and E2, in samples stored before the onset of CAD (Cardiac group) or at matched times (Control group). Body mass index, blood pressure, and total serum cholesterol were measured at each visit. Both systolic blood pressure (SBP; P less than 0.001) and cholesterol (P less than 0.001) were increased in the Cardiac group, but no significant differences were found in total or free T or E2, the ratio of E2/T, or DHEAS between the two groups. The difference in cholesterol was significant only in men less than or equal to 65 years old (P less than 0.001), and SBP only in men greater than 65 years old (P less than 0.005). Cholesterol (P less than 0.05) and E2 (P less than 0.001) appeared to decrease with age in the Cardiac, but not the Control, group. Moreover, total (P less than 0.01) and free E2 (P less than 0.05) were lower only in Cardiac men less than or equal to 55 years old.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗