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PubMed1988

Hemodynamic effects of celiprolol at rest and during exercise; a comparison with enalapril.

The antihypertensive effects of once-daily administration of celiprolol 400 mg were compared with those of once-daily enalapril 20 mg in 20 mild to moderate essential hypertensives in a single-blind study in which the subjects were randomized to 2 weeks' treatment with either drug, preceded by 2 weeks of placebo administration. Supine and standing systolic blood pressure (SBP), diastolic pressure (DBP), and heart rate (HR) were measured at rest and during exercise (exercise bicycle with increasing work loads up to 100 watts) at the end of either period, 20 to 24 hr after drug or placebo administration. Compared to placebo, both celiprolol and enalapril reduced resting supine and standing SBP and DBP to a marked and similar extent; resting HR was unaffected by enalapril, while celiprolol produced modest reductions. During exercise, however, celiprolol significantly attenuated rises in SBP and HR, while enalapril did not. Indexes of cardiac function at rest obtained by echocardiography and systolic time intervals were unaffected by either drug. Thus, despite similar reductions by both drugs in resting blood pressures, celiprolol produced better antihypertensive effects during exercise than enalapril.

Adrenergic beta-Antagonists↗

PubMed1995

Experimental acute hypoxia in healthy subjects: evaluation of systolic and diastolic function of the left ventricle at rest and during exercise using echocardiography.

To clarify whether or not systolic and diastolic function of the human left ventricle (LV) were decreased during acute hypoxia, at rest and with exercise, 14 healthy male volunteers [age 25.9 (SD 3.0) years, height 182.9 (SD 7.1) cm, body mass 75.9 (SD 6.9)kg] were examined using M-mode and 2D-mode echocardiography to determine the systolic LV function as well as Doppler-echocardiography for the assessment of diastolic LV function on 2 separate test days. In random order, the subjects breathed either air on 1 day (N) or a gas mixture with reduced oxygen content on the other (H; oxygen fraction in inspired gas 0.14). Measurements on either day were made at rest, several times during incremental cycle exercise in a supine position (6-min increments of 50 W, maximal load 150 W) and in 6th min of recovery. Corresponding measurements during N and H were compared statistically. Arterial O2 tension (PaO2) was normal on N-day. All subjects showed a marked acute hypoxia at rest [PaO2, 54.5 (SD 4.6) mmHg], during exercise and recovery on H-day. The latter was associated with tachycardia compared to N-day. All echocardiographic measurements at rest were within the limits of normal values on both test days. Ejection time, end-systolic and end-diastolic left ventricular dimensions as well as the thickness of left posterior wall and of interventricular septum showed no statistically significant influence of H either at rest or during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

Plasma vasopressin, neurophysin, renin and aldosterone during a 4-day head-down bed rest with and without exercise.

The purpose of this study was to investigate the main renal and hormonal responses to head-down bed rest, which is currently considered a reliable experimental model for the simulation of weightlessness. Urinary output and electrolytes, plasma renin activity (PRA), aldosterone (PA), antidiuretic hormone (ADH) and immunoreactive neurophysin-I (Np) were measured in eight adult volunteers submitted to a 4-day head-down bed rest (-6 degrees) after a 24-h control period in the horizontal position (day 0). Four of the eight subjects were submitted to two 1-h periods of controlled muscular exercise (50% VO2max) from day 1 to day 4. Throughout the head-down bed rest period, urinary output remained stable, although lower than in the control period (day 0), but the urinary Na/K ratio decreased. Plasma electrolytes and osmolality, and creatinine clearance remained unchanged. There was no significant difference between exercising and non-exercising subjects. At the hormonal level, PRA and PA increased during the head-down bed rest. This increase was more pronounced in the group with exercise. At the end of the tilt period, PRA and PA were about 3 times higher than on day 1. No significant changes could be observed for ADH and Np. It is concluded that a 4-day head-down bed rest results in no apparent changes in neurohypophyseal secretory activity, and in a progressive secondary hyperaldosteronism.

Adult↗

PubMed1985

Haemodynamic effects of indenolol at rest and after a submaximal workload in essential hypertension.

The effect of indenolol on heart rate and blood pressure at rest and after submaximal workload has been studied in 19 patients with established essential hypertension. A stepwise increase from moderate to submaximal exercise was chosen to mimic challenges normally occurring in daily life. After 4 weeks of once a day indenolol therapy a significant, gradual reduction in the following cardiovascular parameters was observed: heart rate at rest fell by 20%, 30% after exercise and 31% after recovery; systolic blood pressure showed a fall of 15% at rest, 19% after workload and 14% after recovery; the reduction in diastolic blood pressure was 15% at rest, 11% after exercise and 12% after recovery. The rate-pressure product was decreased by 32% at rest, 43% after exercise and 42% after recovery. It is concluded that the most important pharmacological effect of indenolol is the significant decrease in myocardial oxygen demand. In patients with essential hypertension indenolol not only produces a definite antihypertensive effect, but it also increases workload tolerance and decreases subjective symptoms during physical activity. Compliance was good and no severe side effects were observed.

Adult↗

PubMed1995

Clinical significance of the resting heart rate in the assessment of autonomic function by cardiovascular reflex tests.

The effect of the resting heart rate on heart rate responses in standard cardiovascular autonomic function tests was studied in a sample of 845 subjects. The responses, which were calculated using instantaneous heart rate changes and R-R interval ratios, were divided into quantiles according to their absolute values. The effect of resting heart rate on each cardiovascular index was studied by linear regression analysis, first in the whole group and then in the group with responses belonging to the lowest quantile. As regards the whole group, eight out of ten indices diminished significantly with increasing resting heart rate. However, no response-attenuating effect of increasing resting heart rate could be found among the responses in the lowest quantile. Since particularly low heart rate responses in cardiovascular reflex testing are of clinical importance when autonomic neuropathy is diagnosed, it can be concluded that the usefulness of standard cardiovascular reflex test based on heart rate changes is not limited by the level of the resting heart rate.

Adolescent↗

PubMed1996

Effects of age on aortic blood velocity at rest and during exercise in patients with coronary artery disease.

The effect of age on aortic blood velocity has been studied in 100 patients with angiographically-documented coronary artery disease, 500 of whom were receiving beta-adrenergic blocking agents. Using continuous-wave Doppler ultrasound, the aortic blood velocity signals, both at rest and at maximal-tolerated supine exercise, were obtained. From the Doppler signals the peak velocity (Vp), stroke distance (Sd; the velocity-time integral) and minute distance (Md = Sd x heart rate) were calculated. The measurements were repeated 6 weeks after coronary artery bypass grafting (CABG), performed in 30 patients. No relationship with age (p < 0.01) was found for any of the indices, either at rest or during exercise, except for the resting Md in patients not on beta-blockers, (p < 0.02). No difference in the slope of the relationship with age was found between patients on or not on beta-blockers, except for the resting Md (p < 0.02). Following CABG, a significant age relationship with Vp, Sd and Md was restored, during both resting and exercise, suggesting improvement of systolic left ventricular function following myocardial revascularization. In conclusion, the normal age relationships of the derivatives of aortic blood velocity Doppler ultrasound signals were not seen in patients with coronary artery disease, irrespective of whether they were on or off beta-blockers. The relationship changed following myocardial revascularization, suggesting their dependence on systolic left ventricular function.

Adrenergic beta-Antagonists↗

PubMed1991

Dose-dependent effects of intravenous lorazepam on cardiovascular activity, plasma catecholamines and psychological function during rest and mental stress.

Dose-dependent effects of intravenously administered lorazepam on psychophysiological activity during rest and mental stress were studied in order to examine differential responses to doses which may induce anxiolysis or sedation. In a double-blind randomized cross-over study, nine male volunteers participated in a placebo and a lorazepam session, during which the subjects repeatedly performed a 10-min version of the Stroop Color Word Test (CWT), with 10 min of rest between the CWTs. Lorazepam was administered before each rest period in increasing doses of 0.0, 0.6, 0.13, 0.25 and 0.5 mg (total cumulative dose: 0.94 mg). Heart rate showed a dose-dependent decrease during rest with an ED50 of 0.13 mg lorazepam, while lorazepam had no effect on the cardiovascular and plasma catecholamine response magnitudes to the CWT. Subjective fatigue and reaction time increased significantly after 0.94 mg lorazepam, while at the same dose vigor decreased; state anxiety after the CWT was not influenced by lorazepam. These data show differential effects of lorazepam on cardiovascular, biochemical and psychological function. While heart rate was suppressed at low doses during rest and reaction time and subjective fatigue increased at doses which induced sedation, state anxiety and physiological response patterns to the CWT were not influenced by lorazepam.

Adult↗

PubMed2006

Substrate source utilisation in long-term diagnosed type 2 diabetes patients at rest, and during exercise and subsequent recovery.

AIMS/HYPOTHESIS: Disturbances in substrate source metabolism and, more particularly, in fatty acid metabolism, play an important role in the aetiology and progression of type 2 diabetes. However, data on substrate source utilisation in type 2 diabetes are inconclusive. METHODS: [U-(13)C]palmitate and [6,6-(2)H(2)]glucose tracers were used to assess plasma NEFA and glucose oxidation rates and to estimate the use of muscle- and/or lipoprotein-derived triacylglycerol and muscle glycogen. Subjects were ten male patients who had a long-term (7 +/- 1 years) diagnosis of type 2 diabetes and were overweight, and ten matched healthy, male control subjects. Muscle biopsy samples were collected before and after exercise to assess muscle fibre type-specific intramyocellular lipid and glycogen content. RESULTS: At rest and during exercise, the diabetes patients had greater values than the controls for palmitate rate of appearance (Ra) (rest, 2.46 +/- 0.18 and 1.85 +/- 0.20 respectively; exercise, 3.71 +/- 0.36 and 2.84 +/- 0.20 micromol kg(-1) min(-1)) and rate of disappearance (Rd) (rest, 2.45 +/- 0.18 and 1.83 +/- 0.20; exercise, 3.64 +/- 0.35 and 2.80 +/- 0.20 micromol kg(-1) min(-1) respectively). This was accompanied by significantly higher fat oxidation rates at rest and during recovery in the diabetes patients (rest, 0.11 +/- 0.01 in diabetes patients and 0.09 +/- 0.01 in controls; recovery, 0.13 +/- 0.01 and 0.11 +/- 0.01 g/min respectively), despite significantly greater plasma glucose Ra, Rd and circulating plasma glucose concentrations. Furthermore, exercise significantly lowered plasma glucose concentrations in the diabetes patients, as a result of increased blood glucose disposal. CONCLUSION: This study demonstrates that substrate source utilisation in long-term-diagnosed type 2 diabetes patients, in whom compensatory hyperinsulinaemia is no longer present, shifts towards an increase in whole-body fat oxidation rate and is accompanied by disturbances in fat and carbohydrate handling.

Biopsy↗

PubMed1998

Post-rest contraction amplitude in myocytes from failing human ventricle.

It has been reported that the balance between the two main Ca2+ removal systems in the cardiac cells, the sarcoplasmic reticulum (SR) and Na+/Ca2+ exchanger, is altered in failing human heart. We have studied post-rest contraction behaviour as a non-invasive probe of the amount of Ca2+ stored in the SR in myocytes from failing and non-failing human ventricle. The first beat following a rest interval, as a percentage of the preceding steady state (B1/SS), was larger and more variable in cells from failing heart, indicating some accumulation of Ca2+ in the SR during rest. This could be mimicked by treatment of myocytes with digoxigenin, a compound which increases intracellular Na+, suggesting that alterations in the Na+ balance of the cell might contribute to the effect. Isoprenaline, which stimulates Ca2+ uptake by the SR while the myocyte is beating, prevented SR Ca2+ accumulation during rest in susceptible myocytes. We hypothesize that loss of SR function in the failing heart is partially compensated for by increased Ca2+ extrusion via the Na+/Ca2+ exchange in the contracting myocyte, leading to increased intracellular Na+ during activity. This Na+ is lost at rest, predisposing the cells to accumulate Ca2+ in the SR. Experiments to test this hypothesis are proposed.

Analysis of Variance↗

PubMed2000

Leg-press resistance training during 20 days of 6 degrees head-down-tilt bed rest prevents muscle deconditioning.

The purpose of this study was to investigate the effects of resistance training on the morphological and functional properties of human lower limb muscles during 20 days of 6 degrees head-down-tilt bed rest. Nine men were randomly assigned to the resistance training group (BR-Tr, n = 5) or the non-training, control group (BR-Cont, n = 4). Isometric leg-press exercises were performed: 3 s x 30 repetitions (30 s rest between repetitions) daily for 20 days during the bed-rest period. Serial axial magnetic resonance images were taken from the right thigh and leg muscles, and muscle volume, muscle length, and fibre length were estimated. The physiological cross-sectional areas (PCSAs) of the knee extensor, knee flexor, ankle plantarflexor, and ankle dorsiflexor (tibialis anterior) muscle groups were determined as muscle volume multiplied by the cosine of the angle of fibre pennation divided by fibre length. Maximum voluntary contraction (MVC) during knee extension was measured. No significant changes were observed in the PCSA of the knee extensor muscles in BR-Tr group, whereas the PCSA in the BR-Cont group decreased by 7.8%. The PCSA of the knee flexor and plantarflexor muscles in the BR-Tr group and BR-Cont group significantly decreased after bed rest (knee flexors, 10.2% and 11.5%; plantarflexors, 13.0% and 12.8%, respectively). However, in both groups bed rest had no effect on the muscle volume and PCSA of the tibialis anterior. MVC was maintained by resistance training in the BR-Tr group (decreased by 1%). In contrast, a decline of strength was observed in the BR-Cont group (-16%), but this result was not statistically significant. These results suggest that isometric leg-press training prevents the deconditioning (i.e. atrophy and decline of strength) of the knee extensor muscle group.

Adult↗

PubMed2001

Enhanced flow-dependent vasodilatation after bed rest, a possible mechanism for orthostatic intolerance in humans.

We investigated the alteration in flow-dependent-dilatation in the orthostatic intolerance occurring after bed-rest deconditioning. Eight men [aged mean (SEM) 32 (2) years] underwent two consecutive periods of 7 days of head-down-tilt (HDT, -6 degrees) during bed rest. A control age and sex matched group [n = 8, 30 (2) years], maintained its usual physical activity. Blood flow velocity (BFV) and diameter (Doppler and echotracking systems) were measured in the brachial artery, under basal conditions and during the post ischaemic hyperaemia following occlusion. The increase in BFV post-ischaemia did not change before, during and after HDT but the relative increase in the diameter was greater on the 7th day of the HDT period than before HDT [+8.8(1.6)% compared to +3.7(1.0)%, P < 0.001]. After HDT, 11 of 16 standing tests (comprising eight subjects in the two HDT periods) had to be stopped because of orthostatic intolerance. The flow-dependent-dilatation measured at the end of HDT was negatively correlated with the post-bed-rest duration of orthostatic tolerance (r = 0.78, P < 0.01). After the sublingual administration of glyceryl trinitrate, there was no change in the increase in diameter. No significant changes were observed in the control group. Bed-rest deconditioning enhances the flow-dependent vasodilatation of large arteries and might contribute to the orthostatic intolerance observed following bed-rest.

Adult↗

PubMed2005

Resting anal pressure following hemorrhoidectomy and lateral sphincterotomy.

PURPOSE: The role of high anal pressure in the pathophysiology of hemorrhoids and anal fissures is debated. We compared resting anal pressures following left lateral sphincterotomy and hemorrhoidectomy in a prospective manometric study with emphasis on the recovery of the internal anal sphincter activity. METHODS: Included in the study were 38 patients with third-degree or fourth-degree symptomatic hemorrhoids who underwent hemorrhoidectomy, 50 patients with anal fissure who underwent sphincterotomy, and 12 healthy patients who served as controls. All patients with anal fissure or hemorrhoids underwent periodic manometric evaluation: 1 month before surgery and 1, 3, 6, and 12 months after surgery. The control group had three manometric evaluations 6 months apart. RESULTS: Baseline pressure measurement in the fissure group was significantly higher than in the hemorrhoid group, which was significantly higher than in the control group (138 +/- 28.4 mmHg vs. 108.4 +/- 23 mmHg vs. 73 +/- 5.9 mmHg, P < 0.0001). Twelve months after surgery, anal resting pressure remained significantly lower than the baseline measurements in both the fissure (110 +/- 18.2 vs. 138 +/- 28.4, P < 0.0001) and hemorrhoid groups (103.6 +/- 21.5 vs. 108 +/- 23, P < 0.0001), but both remained higher than the control group (103.6 +/- 21.5 mmHg vs. 73 +/- 5.9 mmHg, P < 0.0001). CONCLUSIONS: Resting pressure is elevated in hemorrhoid and anal fissure patients. After surgery the anal resting pressure is reduced but is still higher than in the control group. Further studies are required to investigate the protective effect of postsurgical reduction of anal resting pressure against recurrence.

Adult↗

PubMed1982

Assessment of left ventricular function by resting and exercise radionuclide angiocardiography following acute myocardial infarction.

Left ventricular function was evaluated by first-pass radionuclide angiocardiography in 42 patients at 3 and 8 weeks following acute myocardial infarction. Left ventricular ejection fraction, diastolic volume, and wall motion were measured at rest and submaximal exercise at 3 weeks and at rest, submaximal and maximal exercise at 8 weeks. The mean ejection fraction, end-diastolic volume, and wall motion index did not change between 3 and 8 weeks in any group either at rest or during submaximal exercise. Ventricular function was decreased at rest in patients with previous and anterior myocardial infarctions, but not in patients with inferior and subendocardial myocardial infarctions. During maximal exercise at 8 weeks, nine patients (21%) had ST segment depression, whereas 25 patients (60%) had a decrease in ejection fraction or a deterioration in wall motion. These abnormalities of ventricular function during exercise occurred equally among the infarct groups. Radionuclide angiography in patients with recent myocardial infarction demonstrated highly variable ventricular function at rest and/or during exercise in each infarct subgroup.

Adult↗

PubMed1993

A randomized comparison between the hemodynamic effects of hydralazine and nitroglycerin alone and in combination at rest and during isometric exercise in patients with chronic mitral regurgitation.

Both arteriolar vasodilation with hydralazine and venodilation with nitroglycerin have been shown to favorably alter the hemodynamic profile in patients with chronic mitral regurgitation. Since these therapeutic modalities exert their effects by different mechanisms, this study was designed to assess hemodynamic response to both drugs given individually and in combination at rest and during isometric exercise in patients with chronic mitral regurgitation of various etiologies. When used individually, hydralazine caused larger increase in heart rate, cardiac index, stroke volume index, and systemic vascular resistance both at rest and during exercise. In contrast, nitroglycerin administration was associated with a superior effect on mean pulmonary artery pressure and V wave amplitude at rest and on mean right atrial and mean pulmonary artery wedge pressures at rest and during isometric exercise. In comparison with hydralazine alone, combination therapy enhanced the reduction in right atrial pressure (4 +/- 1 versus 0 +/- 2 mm Hg, p < 0.05), mean pulmonary arterial pressure (11 +/- 5 versus 1 +/- 3 mm Hg, p < 0.05), and the V wave amplitude (15 +/- 6 versus -5 +/- 3 mm Hg, p < 0.05) at rest and resulted in a larger reduction in exercise values of mean pulmonary artery pressure (-11 +/- 7 versus -3 +/- 5 mm Hg, p < 0.05) and mean pulmonary arterial wedge pressure (-11 +/- 5 versus -5 +/- 3 mm Hg, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1981

Effect of verapamil and nifedipine on left ventricular function at rest and during exercise in patients with Prinzmetal's variant angina pectoris.

To assess the effects of verapamil and nifedipine on left ventricular function at rest and during exercise in patients with Prinzmetal's variant angina pectoris, 10 patients (6 men and 4 women with a mean age of 52 years) with variant angina were each treated for 2 months periods with placebo, verapamil (400 +/- 80 mg/day, mean +/- standard deviation [SD]) and nifedipine (82 +/- 31 mg/day). During the final week of each 2 month treatment period equilibrium gated blood pool scintigraphy was performed at rest and during exercise. At rest, heart rate during verapamil therapy was lower than during treatment with nifedipine; systolic blood pressure and left ventricular volumes and ejection fraction were similar for the three interventions. The maximal work load achieved was similar during placebo, verapamil and nifedipine therapy. At the maximal work load common to all three exercise studies, heart rate and systolic blood pressure were lower with verapamil than with placebo and nifedipine; ventricular volumes and ejection fraction were similar with the three agents. Thus, in patients with variant angina and a wide range of left ventricular function at rest, neither verapamil nor nifedipine significantly alters left ventricular volumes or ejection fraction at rest or during exercise.

Angina Pectoris↗

PubMed1981

Lack of correlation between exercise capacity and indexes of resting left ventricular performance in heart failure.

Symptoms of congestive heart failure occur most commonly during exercise, but cardiac performance is usually quantitated at rest. The relation between exercise capacity and measurements of cardiac performance at rest is little known. Treadmill exercise was performed in 21 patients with heart failure due to cardiomyopathy. Exercise duration averaged 9.1 +/- 0.7 (standard error of the mean) minutes (normal value 12 or more minutes) and did not correlate with resting ejection fraction of 26.4 +/- 2.7 percent (r = -0.06). Left ventricular diastolic dimension of 6.6 +/0 0.2 cm, mean velocity of circumferential fiber shortening and ratio of preejection period to left ventricular ejection time did not correlate with treadmill time (r = -0.03). Repeat studies after treatment of heart failure also failed to show correlations between changes in exercise capacity and changes in left ventricular performance at rest. Thus, measures of left ventricular performance obtained at rest do not accurately reflect exercise tolerance and symptomatic status of patients with congestive heart failure.

Adult↗

PubMed1985

Effects of intravenous infusion of esmolol and propranolol on biventricular performance at rest and during exercise as assessed by quantitative radionuclide angiography.

This double-blind, randomized, crossover study examined the effects of intravenous infusion of esmolol (a new ultra-short-acting beta-receptor blocking agent) and propranolol on cardiovascular performance at rest and during peak upright exercise in 15 patients. Biventricular function was assessed by means of first-pass radionuclide ventriculography with a computerized multicrystal camera. At rest, significant treatment differences between esmolol and propranolol vs baseline were found for the heart rate, systolic blood pressure, double product, left ventricular ejection fraction (EF), systolic blood pressure to end-systolic volume ratio, cardiac index and right ventricular EF. During exercise, significant treatment differences were also found for the heart rate, systolic blood pressure, double product, right ventricular EF and cardiac index. The mean baseline measurements were higher than the mean treatment measurements, but no significant differences were found between mean esmolol and mean propranolol measurements at rest and during exercise except for the exercise systolic blood pressure, which was lower during esmolol infusion. The magnitude of drug effect was greater at the time of exercise than at rest. The blood level of esmolol decreased markedly by 30 minutes after infusion. Esmolol was well tolerated, with no important local, systemic or laboratory abnormalities. Thus, the effects of esmolol on cardiovascular performance at rest and exercise are similar to those of propranolol.

Aged↗

PubMed1985

Radionuclide assessment of ventricular contraction at rest and during exercise following the Fontan procedure for either tricuspid atresia or single ventricle.

Ventricular contraction was evaluated in 18 patients studied at a mean of 2.6 years after Fontan repair. The diagnosis was tricuspid atresia in 9 patients and single ventricle in 9. Gated first-pass and gated equilibrium radionuclide ventriculography were performed at rest and during exercise. Abnormally low ventricular ejection fraction (EF) at rest was present in 8 of 18 patients by the gated equilibrium technique and 6 of 13 technically adequate gated first-pass studies. An abnormal response to exercise (failure of EF to increase less than or equal to 5% from rest to maximal exercise) was found in 10 of 16 patients by the gated equilibrium technique and in 8 of 12 by the gated first-pass technique. Only 2 patients by each radionuclide technique had both normal EF at rest and normal exercise response. Thus, this study confirms the frequent presence of abnormalities in ventricular contraction after the Fontan procedure at rest or during exercise or both despite absence of symptoms. Both EF response and the hemodynamic response during exercise were more abnormal in the presence of an atriopulmonary than an atrioventricular connection.

Adolescent↗