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Biomedical subjects

L Vanhees

Publications and source records attributed to L Vanhees.

48 records · Page 3Linked to original sources
PubMed1984

Influence of beta-adrenergic blockade on the hemodynamic effects of physical training in patients with ischemic heart disease.

Beta-blocking agents are widely used in the treatment of patients with coronary artery disease. Their negative chronotropic and inotropic actions may alter the effects of physical training in cardiac rehabilitation programs. Therefore, resting and exercise cardiac output, stroke volume, heart rate, and arteriovenous oxygen content difference were measured before and after training in 15 male patients with coronary artery disease, who were treated with beta blockers, and in a control group of 14 patients not treated with beta-blocking agents. At the end of a 3-month training period, oxygen uptake at peak exercise increased similarly in the two groups, 37% and 34%, respectively; this was related to increases in stroke volume and heart rate, and therefore cardiac output, and to increases in arteriovenous oxygen content difference. The effects were similar whether or not the patients were treated with beta blockers. Also, at rest and submaximal exercise, beta blockade did not affect the training-induced changes of cardiac output, heart rate, and arteriovenous oxygen content difference. In both groups heart rate decreased with training while stroke volume and cardiac output increased significantly. In conclusion, beta blockade did not significantly alter the hemodynamic effects of training.

Adrenergic beta-Antagonists↗
PubMed1984

Responses of the systemic circulation and of the renin-angiotensin-aldosterone system to ketanserin at rest and exercise in normal man.

The systemic circulation at rest and during exercise was studied in ten normal male volunteers, after placebo on one occasion and after acute intravenous administration of the serotonergic antagonist ketanserin on another occasion. The effects of ketanserin on the components of the renin-angiotensin-aldosterone system, on plasma catecholamines and on exercise capacity for graded uninterrupted exercise were also investigated. At rest in recumbency rapid intravenous injection of 10 mg of ketanserin, followed by a continuous infusion of 2 mg/h, produced an acute but transient fall in mean intra-arterial pressure of 6 mmHg compared with placebo. After 15 min the mean arterial pressure with ketanserin was within 2 mmHg of the mean pressure with placebo. In the sitting position both at rest and up to 30% of maximal work rate, the mean arterial pressure during ketanserin did not differ from the pressure on placebo. However, at higher levels of physical activity the rise in mean arterial pressure was lower with ketanserin; the pressure achieved with placebo was 7.5 mmHg higher at maximal work rate. Heart rate and cardiac output were significantly higher during ketanserin. When the subjects were lying down and resting, plasma noradrenaline and adrenaline levels, plasma renin activity and angiotensin II concentration were not affected by ketanserin; however, these values were higher in the sitting position both at rest and during exercise. Plasma aldosterone was reduced by ketanserin during exercise and also when the subject was resting in the recumbent position.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

The effects of beta blockers on exercise capacity and on training response in elderly subjects.

Treatment of 8 hypertensive elderly subjects with atenolol or with labetalol did not affect exercise performance, except after the development of circulatory congestion in 1 patient. Treatment with beta blockers did not alter the response to an exercise training programme in 15 elderly patients with ischaemic heart disease, as compared with 11 patients without such treatment.

Aged↗
PubMed1984

Cardiac structure and function in cyclists and runners. Comparative echocardiographic study.

Twelve cyclists and 12 long distance runners matched for age, height, and weight with two control groups of 12 non-athletes were studied echocardiographically to evaluate cardiac structure and function. Runners weighed 8 kg less than cyclists, but age and height were similar. Peak oxygen uptake per kg body weight was higher in athletes than in the control subjects but was similar in the cyclists and in the runners. The athletes' hearts had a larger end diastolic left ventricular internal diameter, mean wall thickness, and cross sectional area of the left ventricular wall than those of the respective control subjects. Nevertheless, whereas the left ventricular internal diameter was not different between the cyclists and runners, mean wall thickness and cross sectional area of the left ventricular wall were greater in the cyclists even after adjustment for weight. The ratio of wall thickness to left ventricular internal radius was significantly larger in cyclists than in their control group, but the ratio was similar in runners and their control group. The echocardiographic indices of left ventricular function were similar in the athletes and the control groups. Systolic left ventricular meridional wall stress was lower in the cyclists than in the runners. The data suggest that runners develop an increase in left ventricular wall thickness which is proportionate to the internal diameter but that in cyclists the increase is disproportionate because of the isometric work of the upper part of the body during cycling.

Adolescent↗
PubMed1984

Changes in systolic time intervals during physical training in patients with ischemic heart disease. Effect of beta-blockade.

Systolic time intervals (STI) were measured at rest before and after an exercise training programme in 37 patients with ischemic heart disease; 17 patients were treated with a beta-blocking drug (BB-group) and 20 were not (nBB-group). After the training period peak oxygen uptake had increased by 37% in the BB-patients and by 41% in the nBB-group. During the training period electromechanical systole (QS2) and pre-ejection period (PEP), when corrected for heart rate, shortened significantly in all 37 patients. Left ventricular ejection time (LVET) increased but when corrected for heart rate no significant changes occurred. The ratio of PEP/LVET decreased significantly. The changes in STI were similar in the patients treated with beta-blocking drugs than in those without such treatment. The changes in STI in both groups suggest that left ventricular function improves during the training period and that beta-adrenergic blockade does not alter this outcome.

Adrenergic beta-Antagonists↗
PubMed1983

The effect of physical training on the left apexcardiogram.

Indices of the first derivative and of the normalized first derivative of the left apexcardiogram were used to evaluate the contractile state of the left ventricle of cyclists in the competitive season compared to their resting season and of cardiac patients before and after a physical training program. In both groups exercise capacity increased after training (P less than 0.001). The normalized first derivative of the upstroke of the systolic wave and the time from the onset of electrical depolarization to the peak value of the first derivative of the upstroke of the systolic wave were unchanged after training in both groups. Also in both groups training did not alter the height of the A-wave in percentage of the amplitude of the systolic wave nor the normalized first derivative of the A-wave. These indices suggest that the compliance of the left ventricle was not decreased despite thickened left ventricular walls as reported in both groups. Thus physical training does not seem to alter the intrinsic myocardial contractile state, as far as reflected by these indices of the left apexcardiogram.

Adolescent↗
PubMed1982

Influence of beta adrenergic blockade on effects of physical training in patients with ischaemic heart disease.

Reduction in heart rate during submaximal exercise is often used to judge the progress of patients with ischaemic heart disease in the course of a physical training programme. Some patients, however, are treated with beta adrenergic blocking drugs and it remains controversial if chronic beta blockade influences the effects of training and if heart rate remains a useful guide in the evaluation of the state of training of these patients. Male postinfarction patients, 15 treated with and 15 without beta blockers, were trained for three months, three times a week. Cardiorespiratory results from uninterrupted incremental exercise tests before and after training were compared. In each subgroup, the heart rate and systolic blood pressure were significantly reduced. For heart rate the decrease after training became more pronounced with increasing work load and the overall reduction was significantly less in the beta blocker group compared with the patients not treated with beta blockers. For systolic blood pressure the training-induced reductions were more pronounced in the patients on beta blockers. The increase of peak oxygen uptake was similar in the patients with and without beta blockers, namely 36% and 34.5%. At submaximal exercise carbon dioxide output, pulmonary minute ventilation, and the respiratory exchange ratio were lower after training, and these effects of training were similar whether or not the patients were on beta blockers. The study shows that the usual effects of training are observed in patients on beta blockers, and that heart rate remains a useful guide to their evaluation throughout a physical training programme.

Adrenergic beta-Antagonists↗
PubMed1982

Hemodynamic response to converting enzyme inhibition at rest and exercise in humans.

The response of the systemic circulation to acute inhibition of the converting enzyme with 25 mg of oral Captopril (Squibb) was studied in six normal sodium-replete male volunteers at rest and during exercise, together with its effects on exercise capacity for graded uninterrupted exercise. In recumbent subjects at rest Captopril did not affect arterial pressure or heart rate, and plasma renin activity rose 2.5-fold (P less than 0.05). In subjects in the sitting position, at rest and during exercise until exhaustion, Captopril reduced mean brachial intra-arterial pressure by an average of 7 Torr in comparison to placebo (P less than 0.001). Captopril's hypotensive effect was caused by a reduction of systemic vascular resistance (P less than 0.01), without changes of cardiac output (measured by CO2 rebreathing), heart rate, or stroke volume. Plasma renin activity was significantly higher during Captopril (P less than 0.001). Peak oxygen uptake and exercise duration were the same after administration of Captopril or placebo. The data demonstrate that the renin-angiotensin system is not involved in the homeostasis of blood pressure in supine sodium-replete humans, but has a modest role in blood pressure regulation when posture is changed from supine to upright. The orthostatic effect of Captopril is maintained during upright exercise. Furthermore the reduction of systemic vascular resistance by Captopril does not affect peak oxygen uptake.

Adult↗
PubMedDate not supplied

Influence of beta 1- versus beta 2-adrenoceptor blockade on left ventricular function in humans.

Pharmacological and radio-ligand binding studies have recently indicated the existence of beta 2-adrenoceptors in the human heart. Their physiological role, however, remains to be elucidated. The present study investigated in 17 normal, young volunteers the effect on resting left ventricular (LV) function of two types of beta-blockers; a predominant beta 1-adrenoceptor antagonist (atenolol, 50 mg once daily) and ICI 118,551 (20 mg t.i.d.), a new, predominant beta 2-antagonist. LV function was assessed using M-mode echocardiograms and systolic time intervals. Atenolol, ICI 118,551, and placebo were given according to a randomized, double-blind, cross-over protocol. As compared with placebo, both drugs caused a decrease in resting heart rate, but the reduction by ICI 118,551 was less pronounced. Systolic blood pressure was only reduced by atenolol 8 mm Hg on average. Cardiac output was decreased to the same extent following treatment with atenolol (-20%) as after ICI 118,551 (-17%). These decreases in cardiac output were related to the beta-blocker-induced bradycardia, since stroke volumes were not affected during either selective beta 1- or beta 2-blockade. In addition, all other echocardiographic variables reflecting LV pump function, such as fractional shortening, velocity of diameter change and of displacements, pre-ejection period, and the ratio of PEP/LVET, were not different from placebo. We conclude that in normal young subjects, global LV pump function is not affected by beta 1- or by beta 2-blockade, despite the negative chronotropic effect of both drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Exercise performance and training in cardiac patients with atrial fibrillation.

PURPOSE: Exercise training in cardiac patients with chronic atrial fibrillation (AF) has received little attention in the literature. Therefore, this study compared exercise performance and the effect of an exercise training program over a period of 3 months in patients with and without AF. METHODS: Data in patients with AF (n = 19) were compared with a control group of patients in sinus rhythm (n = 44), drawn from a database of 2,116 patients. Patients performed a maximal exercise test on the bicycle until exhaustion before and after an ambulatory exercise training program where exercise training was offered 3 times a week for 3 months. RESULTS: Before training, peak oxygen uptake (VO2) was significantly lower in patients with AF compared with the control group (1271 +/- 368 versus 1496 +/- 414 mL/min, P < 0.05). Exercise training significantly increased peak VO2 in both groups (+31%, P < 0.001 in AF and +25%, P < 0.001 in the control group). The gain in peak VO2 did not significantly differ between both groups. A significant decrease in resting heart rate was achieved in both groups after exercise training. AF was also a significant and independent determinant of peak VO2 in the total database, but not of the change in peak VO2. CONCLUSIONS: Exercise training significantly improves exercise performance in cardiac patients with AF. AF affects exercise performance but does not impair the beneficial effects of training. Patients with chronic AF should therefore not be dissuaded from participating in exercise training after a cardiac event.

Aged↗