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PubMed1978

EXERCISE TESTING AND LEFT MAIN CORONARY ARTERY DISEASE: EXPERIENCE WITH 57 PATIENTS.

Results of multistage treadmill tests (TMT) of 57 patients with critical stenosis (>/= 50%) of the left main coronary artery were analyzed. Additional disease was present in the major vessel in three patients (5%), two vessels in 18 patients (32%), and three vessels in 35 patients (61%). The TMT was negative for ischemia in only two patients (4%), positive in 51 (89%), and undetermined in 4 (7%). TMT was strongly positive (>/= 2 mm ST segment depression) in 40 patients (70%), and in 11 (19%) of these, ST depression was >/= 3 mm. Hypotension with exercise was rare and was encountered in only one patient. Arrhythmias were induced with exercise in six patients (10%) and resulted in premature termination of TMT in four. TMT was terminated due to early ST segment depression in 40 patients (70%), in 17 (30%) without chest pain-an unusual finding. Exercise was limited to stage I (Bruce protocol) in 16 (28%), stage II in 26 (46%), stage III in ten (17%), and stage IV in five (9%). Mean exercise tolerance was 298 +/- 22 seconds (SEM). Maximum heart rate (HR) achieved was 76 +/- 2% of their maximal predicted values. Peak double product (systolic BP x HR) was 20490 +/- 830. The data suggest that the TMT is rarely negative in the presence of LM lesions. An early strongly positive response with or without pain should lead one to suspect LM disease. Exercise-induced hypotension is rare. Limited exercise tolerance and/or early ST segment depression in stages I and II of TMT seem to be predictive of the severity of LM lesions.

Journal Article↗

PubMed1996

Carnitine-related alterations in patients with intermittent claudication: indication for a focused carnitine therapy.

BACKGROUND: Carnitine metabolism is altered in peripheral arterial disease. L-carnitine supplementation may correct these alterations and improve walking performance. METHODS AND RESULTS: Plasma levels of carnitine and its esters were measured at rest and after maximally tolerated exercise in 22 claudicant patients and 8 normal subjects. One week later, this protocol was repeated in patients after random administration of placebo or L-carnitine (500 mg IV as a single bolus). Two groups of patients emerged. In 10 patients (group IC1), the plasma level of acetylcarnitine at rest was 3.7 +/- 0.2 micromol/L and increased significantly (P<.01) at maximally tolerated exercise. In 12 patients (group IC2), the resting level of plasma acetylcarnitine was elevated (7.9 +/- 0.7 micromol/L, P<.01) and decreased with exercise. Furthermore, group IC2 patients had a significantly lower walking capacity than group IC1 patients. In both groups, placebo did not affect the metabolic profile, nor did it improve exercise performance. Conversely, after L-carnitine administration, all but one patient in group IC2 (n=7) showed an increase in plasma acetylcarnitine concentration during exercise versus the decrease observed without L-carnitine. This metabolic effect was accompanied by a significant increase (P<.01) in walking capacity. Interestingly, in group IC1 patients (n=5), L-carnitine neither improved walking capacity nor modified the metabolic profile. Statistical analysis showed that changes in walking capacity with L-carnitine treatment were influenced exclusively by exercise-induced changes in plasma acetylcarnitine. CONCLUSIONS: In patients with intermittent claudication, assessment of plasma acetylcarnitine at rest and after exercise may be a means to select a target population for L-carnitine therapy.

Acetylcarnitine↗

PubMed1998

Differences between male and female patients with regard to baseline demographics and clinical outcomes in the Asymptomatic Cardiac Ischemia Pilot (ACIP) Trial.

BACKGROUND: Coronary artery disease (CAD) is a common problem in men and women; however, men and women with similar clinical presentations of myocardial ischemia may receive different revascularization treatments. HYPOTHESIS: Using the data base of the Asymptomatic Cardiac Ischemia Pilot (ACIP) trial, this study was undertaken to compare by gender the baseline demographic data and the clinical outcome results in patients randomized to various treatments in the ACIP study. METHODS: This randomized trial compared three treatment regimens [pharmacologic management of angina, pharmacologic management of angina and ambulatory electrocardiographic (ECG) evidence of ischemia, and revascularization--that is, angioplasty and coronary artery bypass surgery], in patients with known CAD, positive stress ECG tests, and ECG evidence of ischemia during 48 h ambulatory monitoring. In all, 558 patients were randomized, 79 of whom were women (mean age: men 61.6 years, women 60.6 years) Ambulatory ECG evidence of ischemia, clinical events, that is, death, myocardial infarction, hospital admission for coronary events, and exercise performance were monitored. RESULTS: Although of the same age as men at baseline, women had a higher prevalence of hypertension and diabetes. Women had less severe CAD by angiography and higher left ventricular ejection fractions. Men had longer exercise tolerance times on the treadmill. However, men and women had similar numbers and duration of ambulatory ECG ischemic abnormalities. Regarding revascularization, men more commonly underwent coronary artery bypass surgery (p = 0.025) while women underwent percutaneous transluminal coronary angioplasty more frequently (p = 0.10). Clinical outcomes were comparable in men and women, although the numbers of events were relatively small. CONCLUSIONS: Men and women of comparable age manifest CAD with similar ischemic ECG abnormalities seen on both exercise tolerance and ambulatory ECG examinations. In ACIP, women tended to have more risk factors for CAD and less severity in anatomical disease, which may explain why women are less likely than men to have coronary bypass surgery.

Coronary Disease↗

PubMed1992

Tolerance, rebound, and time-zero effect of nitrate therapy.

Both nitroglycerin and long-acting nitrates have proved effective in treating acute anginal pain. In recent years, however, development of tolerance with the continuous use of these agents has been documented. A pilot study demonstrated attenuation of the therapeutic effect of high-dose, continuous transdermal nitroglycerin therapy, despite adequate plasma nitroglycerin levels. In a subsequent, larger Transdermal Nitroglycerin Cooperative Study, evidence of tolerance was detected within 24 hours of initiation of continuous nitroglycerin patch therapy at several different dose levels. Sustained pharmacologic activity has been achieved with the intermittent use of transdermal nitroglycerin, usually for 12 hours followed by a 12-hour drug-free period. When the patch is discontinued, however, some patients experience exacerbation, or rebound, of anginal symptoms and a worsening of exercise tolerance at the end of the drug-free period. Additional clinical research is therefore needed to determine the optimal intermittent dosing strategy.

Administration, Cutaneous↗

PubMed1990

Interval treatment of coronary artery disease with sustained-release isosorbide-5-mononitrate.

The possibility of maintaining preload reduction and enhancement of exercise tolerance during an interval treatment with 50 mg/day of sustained-release isosorbide-5-nitrate (IS-5-N) was investigated in 13 patients (aged 54.4 +/- 7.9 years [mean +/- standard deviation]) with angiographically confirmed coronary artery disease and chronic stable angina pectoris. The effects of a single dose (acute test) were compared with those following an 8-day (chronic) regimen of mononitrate administration. Two hours after administration of 50-mg sustained-release IS-5-N, mean resting pulmonary arterial pressure (PAP), measured with a Swan-Ganz catheter, was reduced by 27% (p less than 0.01), and at submaximal exercise level (50 W, 3 minutes) by 34% (p less than 0.001). At individually highest comparable work loads mean PAP was reduced by 28% (p less than 0.01), and at maximal work load the PAP reduction was 21% (p less than 0.05). At the end of 1 week of therapy with sustained-release IS-5-N a slight, clinically irrelevant reduction of hemodynamic effects was recorded. Work capacity increased after 1 hour by 60% (408 +/- 104 vs 653 +/- 147 W x min, p less than 0.001)--still significantly above baseline 10 hours after nitrate administration. No difference from baseline was demonstrable 24 hours after medication. During interval therapy the improved work capacity was fully maintained (chronic, 1 hour: 417 +/- 93 vs 679 +/- 160 W x min, p less than 0.001). During interval therapy with sustained-release IS-5-N, hemodynamics and exercise tolerance were durably improved.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Left ventricular pressure-volume and Frank-Starling relations in endurance athletes. Implications for orthostatic tolerance and exercise performance.

BACKGROUND: Endurance athletes have a high incidence of orthostatic intolerance. We hypothesized that this is related to an abnormally large decrease in left ventricular end-diastolic volume (LVEDV) and stroke volume (SV) for any given decrease in filling pressure. METHODS AND RESULTS: We measured pulmonary capillary wedge (PCW) pressure (Swan-Ganz catheter), LVEDV (two-dimensional echocardiography), and cardiac output (C2H2 rebreathing) during lower body negative pressure (LBNP, -15 and -30 mm Hg) and rapid saline infusion (15 and 30 ml/kg) in seven athletes and six controls (VO2max, 68 +/- 7 and 41 +/- 4 ml/kg/min). Orthostatic tolerance was determined by progressive LBNP to presyncope. Athletes had steeper slopes of their SV/PCW pressure curves than nonathletes (5.5 +/- 2.7 versus 2.7 +/- 1.5 ml/mm Hg, p less than 0.05). The slope of the steep, linear portion of this curve correlated significantly with the duration of LBNP tolerance (r = 0.58, p = 0.04). The athletes also had reduced chamber stiffness (increased chamber compliance) expressed as the slope (k) of the dP/dV versus P relation (chamber stiffness, k = 0.008 +/- 0.004 versus 0.031 +/- 0.004, p less than 0.005; chamber compliance, 1/k = 449.8 +/- 283.8 versus 35.3 +/- 4.3). This resulted in larger absolute and relative changes in end-diastolic volume over an equivalent range of filling pressures. CONCLUSIONS: Endurance athletes have greater ventricular diastolic chamber compliance and distensibility than nonathletes and thus operate on the steep portion of their Starling curve. This may be a mechanical, nonautonomic cause of orthostatic intolerance.

Adult↗

PubMed1999

Survivors of childhood cancer: long-term endocrine and metabolic problems dwarf the growth disturbance.

The long-term effects of radiotherapy and chemotherapy are becoming increasingly recognized as the cure rates of certain childhood malignancies improve. The endocrine system is particularly sensitive to cancer therapies. Long-term survivors of childhood cancer who received cranial irradiation have been shown to have lower than predicted height, an increased prevalence of obesity and reductions in strength, exercise tolerance, bone mineral density, quality of life and academic achievement. Growth hormone deficiency (GHD) is the most frequent endocrine deficiency observed following cranial irradiation. Adults with GHD resulting from primary hypothalamic-pituitary disease during childhood have been shown to exhibit a clinical picture similar to that described in long-term survivors of childhood cancer: increased fat mass and reduced lean mass, strength, exercise tolerance, bone mineral density and quality of life. This review considers the possible contribution of GHD to the adverse sequelae observed in long-term survivors of childhood malignancy and includes our preliminary experience in treating 14 adults with GHD resulting from the treatment of childhood malignancies.

Adult↗

PubMed1997

Comparison of changes in respiratory function and exercise oxygen uptake with losartan versus enalapril in congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

In congestive heart failure (CHF), some of the effects of angiotensin-converting enzyme (ACE) inhibitors, such as an increase in exercise oxygen uptake (VO2), are mediated through prostaglandins. Angiotensin (AT1) receptor blockers apparently do not share potentiation of this biosystem. We tested whether losartan improves exercise VO2 in CHF and if the effect is the same as for enalapril. Sixteen men with CHF and 8 volunteers, all nonsmokers and not taking ACE, AT1 receptor, or cyclooxygenase inhibitors, were randomized to receive placebo, enalapril (10 mg 2 times daily), losartan (50 mg/day), each of these 2 drugs plus aspirin (325 mg/day), aspirin, or the same preparations in a reverse order, each for 3 weeks, with a 3-week washout period between treatments. Pulmonary function and VO2 were assessed at the end of each treatment. In CHF, losartan and enalapril caused a similar improvement of VO2 and exercise tolerance, which was absent in controls and was counteracted by aspirin (prostaglandin inhibition) when obtained with enalapril and not with losartan. While on enalapril, we also detected an increase in the diffusing lung capacity for carbon monoxide, which correlated with changes in VO2 and was antagonized by aspirin, suggesting the possibility that a prostaglandin-mediated functional improvement of the alveolar capillary membrane contributes to the rise in VO2. Thus, losartan is as effective as enalapril for exercise VO2 and exercise tolerance, but the mechanism seems to be dissociated from a prostaglandin biosystem activation. Losartan may represent an advancement in CHF because its efficacy on VO2 is similar to that of enalapril, but is not antagonized by aspirin.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1990

Antianginal efficacy of exercise training: a comparison with beta blockade.

Forty men with chronic stable angina and no prior myocardial infarction were studied. Exercise tolerance testing was carried out off treatment and after beta blockade. beta Blockers were stopped and the patients were randomised to a control group and a study group of patients who undertook a one year high intensity training programme. The groups were then restudied. Submaximum heart rate was reduced by 13 beats per minute by training and by 23 beats per minute by atenolol. Training increased the maximum heart rate by 10 beats per minute and atenolol reduced it by 29 beats per minute. The double produce ST threshold was increased from 183 to 205 by training but reduced to 143 by atenolol. Maximum ST depression was similarly reduced by both training and atenolol. As a result of the effects on maximum heart rate, training produced a greater improvement in exercise tolerance than atenolol with a treadmill time increased from 741 seconds to 1272 seconds with training compared with 974 seconds with atenolol. Other variables were similarly affected. Thus the antianginal efficacy of exercise training is as good as that achieved by beta blockade and represents an alternative to such treatment.

Angina Pectoris↗

PubMed1992

Nasal cannula and transtracheal oxygen delivery. A comparison of patient response after 6 months of each technique.

The purpose of this study was to compare the efficacy of transtracheal (TT) oxygen delivery to that of nasal cannula delivery in subjects with chronic obstructive pulmonary disease (COPD). Twenty subjects (14 men, 6 women) were followed for 6 months during nasal cannula delivery. A TT catheter was then inserted, and measurements were repeated during TT use. With TT delivery, subjects required 45% less oxygen at rest and 39% less during exercise (p less than 0.0001). Oxygen use, measured by pounds of oxygen delivered to the home, also decreased, but the magnitude of change was less than anticipated (mean, 14%; range, +4% to -32%). Hospital days decreased from 12 +/- 10 during nasal cannula use to 4 +/- 6 during TT use (p less than 0.002). Exercise tolerance, as measured by a 12-min walk distance, was greater during TT use (p less than 0.0001). No change was seen in spirometry or acid-base balance. Also, no change was seen in Profile of Mood States, Sickness Impact Profile or Katz Adjustment Scale scores. Some problems were encountered relating to use of the catheter (displacement, mucus balls), but they were minor, and most were confined to the initial 2 months of TT use when the tract was immature. Our experience suggests that, in addition to decreasing oxygen flow rate, use of TT delivery may confer benefits that result in improved exercise tolerance and decreased hospitalization in patients with COPD.

Catheterization↗

PubMed1982

The measured effect of stopping smoking on intermittent claudication.

One hundred and twenty-four limbs in patients suffering from intermittent claudication were studied over 10 months. Changes in ankle pressure and treadmill exercise tolerance over the period were compared between two groups, one of patients who continued to smoke (group 1) and the other of those who gave up (group 2). Resting ankle systolic pressure fell in smokers' limbs by a mean of 10.2 mmHg (t = 3.56, P less than 0.001), and rose in those patients who stopped smoking by a mean 8.7 mmHg (P = n.s.). Ankle pressures after exercise and maximum treadmill walking distance did not change in smokers but significantly improved in past smokers. Stopping cigarette smoking increased the chance of improvement in ankle pressure and exercise tolerance in intermittent claudication.

Ankle↗

PubMedDate not supplied

How physicians use the stress test for the management of angina.

The authors examined physicians' reasons for ordering an exercise tolerance test and the influence of the test results on management decisions. Subjects of this study included 265 family physicians in Pennsylvania who completed a questionnaire on the management of a patient with typical chronic stable angina. Eighty-one percent of the respondents reported they would order a noninvasive stress test as a first step in the management of the patient. Of these physicians, 40% would refer the patient to a cardiologist only if the exercise tolerance test were strongly positive, 8% would refer only if it were negative, and 53% would not change their referral decisions on the basis of test results. No more than 57% of the physicians rated as very important any given reason for ordering a noninvasive diagnostic test. The results suggest that a test may be ordered routinely but without a consensus as to why it is ordered and without an effect on clinical management decisions.

Angina Pectoris↗

PubMedDate not supplied

Chronic atrial fibrillation. Success of serial cardioversion therapy and safety of oral anticoagulation.

BACKGROUND: Serial electrical cardioversion is often used for treatment of atrial fibrillation, but its long-term efficacy has not been determined prospectively. OBJECTIVES: To determine the long-term success rate of the serial electrical cardioversion approach in patients with chronic atrial fibrillation, to identify factors that predict its success, and to assess the efficacy and safety of oral anticoagulation in these patients. METHODS: Patients with chronic (> 24 hours) atrial fibrillation received anticoagulant therapy for at least 4 weeks prior to electrical cardioversion. No prophylactic antiarrhythmic agent was given after the first shock. Relapses were managed by using repeated cardioversions, after which serial antiarrhythmic drug therapy was started. Treatment with anticoagulants was withdrawn after 4 weeks of sinus rhythm. RESULTS: Two hundred thirty-six patients were followed up for a mean +/- SD of 3.7 +/- 1.6 years. The actuarial cumulative percentages of patients who maintained sinus rhythm after serial cardioversion treatment was 42% and 27% after 1 and 4 years, respectively. Multivariate analysis showed that factors that were associated with failure of this approach included duration of atrial fibrillation that exceeded 36 months (risk ratio, 5.0; P < .001), poor exercise tolerance (functional class III; risk ratio, 1.8; P = .001), and age older than 56 years (risk ratio, 1.5; P = .04). The anticoagulation level (international normalized ratio, 2.4-4.8) was associated with an incidence of thromboembolic events and bleeding complications of 0.2% and 1.5%, respectively. CONCLUSIONS: Many patients with chronic atrial fibrillation failed to respond to the serial electrical cardioversion strategy. However, in younger patients with a fair exercise tolerance and a duration of atrial fibrillation shorter than 36 months, this approach may be worthwhile. In addition, thromboembolic events were infrequent in the patients who were subjected to this regimen.

Administration, Oral↗

PubMed1999

Why is environmental tobacco smoke more strongly associated with coronary heart disease than expected? A review of potential biases and experimental data.

Despite exposure levels estimated to be equivalent to smoking only 0. 1-1.0 cigarettes per day, exposure to environmental tobacco smoke (ETS) is estimated to increase the risk of death from coronary heart disease (CHD) between 25 and 35% above the risk of nonexposed persons. This surprisingly large risk associated with a seemingly small exposure has raised doubts about the validity of attributing the increased CHD risk to ETS exposure. This paper reviews various biases that have been hypothesized to account for the increased CHD risk associated with ETS in the epidemiologic studies and characterizes the adverse effects of ETS on thrombosis, vascular endothelium, and exercise tolerance observed in experimental studies of humans and laboratory animals. None of the identified factors that has been proposed to introduce a spurious association between ETS and heart disease seem to invalidate the epidemiologic findings, either separately or in combination. In addition, experimental studies of ETS and heart disease demonstrate that acute exposure of humans and other species to ETS affects platelet function, vascular endothelium, and myocardial exercise tolerance at exposure concentrations widely prevalent in the workplace. Because exposure to ETS affects multiple physiologic pathways, it appears biologically plausible that ETS could cause the substantial increase in CHD risk that has been observed in epidemiologic studies.

Animals↗

PubMed2003

[Effects of a short-term home-based pulmonary rehabilitation program in patients with chronic lung disease].

PURPOSE: The purpose of this study is to exam the effects of a short-term pulmonary program on lung function, exercise tolerance, and quality of life in chronic lung patients. METHOD: Randomized controlled pre-post test design was used. The outcome measures were forced expiratory volume in one second (FEV1, % predicted), 6 min walking distance (6MWD), Borg score after 6MWD, and Chronic Respiratory Disease Questionnaire (CRDQ). Experimental group performed the 4-week home-based pulmonary rehabilitation program composed of inspiratory muscle training, upper and lower extremity exercise, relaxation, and telephone visit. Patients in control group were only given education about self-management strategies. Thirty four patients with moderate-to-severe respiratory impairment were recruited, and 28 patients (19 in experiments, 15 in control) completed the study. RESULT: Significant improvements in lung function, exercise tolerance, and health related quality of life were found only in the experiment group. CONCLUSION: This study yielded evidence for the potential and beneficial effects of home-based pulmonary rehabilitation program in patients with moderate to severe chronic lung disease. The program could be adequately utilized for improvement of health related quality of life in chronic lung patients.

Clinical Trial↗

PubMed2006

Acquired idiopathic laryngeal paralysis as a prominent feature of generalised neuromuscular disease in 39 dogs.

A retrospective evaluation of 17 dogs treated surgically for idiopathic acquired laryngeal paralysis demonstrated a marked variability in outcome, with many dogs continuing to exhibit weakness and exercise tolerance. In a subsequent prospective study, 22 consecutive affected dogs were tested for neurological deficits by neurological examination, electrodiagnostic evaluation, and blood analysis to measure thyroxine and thyroid-stimulating hormone and to detect any evidence of myasthenia gravis. Clinical neurological deficits and/or electrodiagnostic abnormalities were found in each case. There was limited evidence that specific neurological deficits were associated with a poor prognosis for full recovery of exercise tolerance. None of the dogs was positive for anti-acetylcholine receptor antibodies, and only three showed evidence of thyroid dysfunction.

Animals↗

PubMed2000

Myasthenia gravis in a collegiate football player.

A 17-yr-old Division I-AA collegiate offensive lineman developed unilateral ptosis shortly after minor head trauma during a scrimmage. The subsequent temporal profile of the ptosis, a history of a similar event lasting a short period of time 2 yr earlier, and the results of his clinical and electrophysiologic examinations established a diagnosis of very mild, generalized, antibody-negative myasthenia gravis (MG). His desire to continue playing football posed several additional management problems for which there was no published guidance. We started him on alternate-day, high-dose prednisone therapy with potassium and calcium supplementation, and allowed him to partake in conditioning but no contact. Except for residual decreased exercise tolerance, he improved symptomatically and experienced no serious adverse effects from the illness or the treatment during his first season, despite imperfect drug compliance. His MG eventually came under excellent symptomatic control, allowing initiation of a slow taper of the prednisone before his second season. Shortly thereafter, he abruptly stopped the prednisone without seeking medical advice. He continued to experience mild left ptosis and a mild decrease in intense exercise tolerance. He decided to forego his senior season of collegiate football after a bout of severe mechanical low-back pain incurred during spring football practice and limited his athletic activity thereafter to recreational sports.

Adolescent↗

PubMed1987

[Evaluation of right ventricular function in severe left ventricular failure: comparison of old myocardial infarction with dilated cardiomyopathy].

To evaluate right ventricular (RV) function in severe left ventricular (LV) failure, we measured RV and LV ejection fractions (EF) in 18 patients with old myocardial infarction (OMI) and in 18 with dilated cardiomyopathy (DCM) using cardiac blood pool scintigraphy. In patients with OMI, RVEF was significantly greater in stage II LV failure than in stage III (functional class of the New York Heart Association, 47 +/- 8% and 28 +/- 12%, respectively: p less than 0.01), and this correlated well with exercise tolerance by bicycle ergometer and mean pulmonary artery pressure (r = 0.83 and r = -0.71, respectively). In patients with DCM, however, there was no correlation between RVEF and these indexes. After the oral administration of denopamine (beta 1 effector), both RVEF and LVEF increased in patients with OMI (35 +/- 13% to 45 +/- 12%, and 27 +/- 9% to 30 +/- 10%: p less than 0.01), but they did not change significantly in patients with DCM. These results indicate that RVEF in patients with OMI correlates well with subjective symptoms, exercise tolerance and RV afterload, but these correlations were not apparent in patients with DCM. We concluded that RV function in cases of severe LV failure has a different meaning between OMI and DCM.

Adult↗