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Biomedical subjects

T L Svendsen

Publications and source records attributed to T L Svendsen.

At least 73 records · Page 4Linked to original sources
PubMed1980

Immediate haemodynamic effects of prenalterol, a new adrenergic beta-1-receptor agonist, in healthy volunteers.

The acute haemodynamic effects of prenalterol, a selective adrenergic beta-1-receptor agonist, were studied in eight healthy male volunteers. Prenalterol was administered i.v. in five increasing doses to a cumulative dose of 5.55 mg. After the last dose of prenalterol, three doses of the selective adrenergic beta-1-receptor antagonist metoprolol were administered i.v. to a cumulative dose of 17.5 mg. After each dose, cardiac output (CO), stroke volume (SV), blood pressure (BP), heart rate (HR), systolic time intervals (STI) and forearm blood flow (FBF) were determined. Prenalterol had the following effects: CO was significantly increased by 21.0% after the fourth dose, but the fifth dose did not further change CO. SV was unchanged after the first four doses, but after the fifth dose a significant decrease in SV of 7.0% was seen. Mean BP was increased significantly by 7.7%, but diastolic BP remained unchanged. HR was increased by 28.4%. Total peripheral resistance was reduced by 8.8%. STI were reduced significantly after the second dose, which indicates that prenalterol has a positive inotropic action. FBF was increased significantly after the fourth dose. After the third dose of metoprolol, the CO, SV, means BP, HR, STI and FBF had returned to their control values. It is concluded that prenalterol has positive inotropic and chronotropic effects on the myocardium, and that metoprolol is a specific antidote.

Adolescent↗
PubMed1980

A comparison of the acute haemodynamic effects of propranolol and pindolol at rest and during supine exercise in man.

1. Dose-response curves for heart rate, cardiac output, arterial blood pressure and pulmonary artery pressure were obtained in 16 male patients after intravenous administration of three increasing doses of pindolol, propranolol or placebo. All patients had an uncomplicated acute myocardial infarction 6-8 months earlier. 2. The dose-response curves were obtained at rest and during repeated bouts of supine bicycle exercise. The cumulative dose amounted to 0.024 mg/kg body weight for pindolol and to 0.192 mg/kg body weight for propranolol. 3. At rest propranolol significantly reduced heart rate and cardiac output by 12% and 15% respectively. Arterial mean blood pressure was reduced by 9.2 mmHg. Mean pulmonary artery pressure increased significantly by 2 mmHg. Statistically significant changes in these variables were not seen after pindolol or placebo. 4. During exercise pindolol and propranolol both reduced cardiac output, heart rate and arterial blood pressure to the same extent. After propranolol mean pulmonary artery pressure was increased significantly by 3.6 mmHg. Pindolol and placebo did not change pulmonary artery pressure significantly. 5. The study suggests that pindolol may offer haemodynamic advantages over beta-receptor-blocking agents without intrinsic sympathomimetic activity during low activity of the sympathetic nervous system, and may be preferable in situations where the beta-receptor-blocking effect is required only during physical or psychic stress.

Adult↗
PubMed1980

Haemodynamic and metabolic effects of combined adrenergic alpha- and beta-receptor blockade with labetalol in the exercising human forearm.

At rest supine acute intravenous administration of the combined adrenergic alpha- and beta-receptor blocking compound labetalol (1 mg/kg body weight) to young, healthy, male subjects, produced a clear-cut fall in arterial blood pressure. During dynamic forearm exercise, forearm blood flow decreased by 17.2%, and calculated vascular resistance increased by 11.3% after labetalol. Forearm oxygen uptake decreased (14.6%), suggesting an increased mechanical efficiency. Lactate release from the exercising forearm decreased (17.6%), probably because of the beta-receptor blockade. Forearm uptake of glucose and free fatty acids remained unchanged. Arterial blood glucose concentration attained a higher level after labetalol. Arterial plasma concentration of FFA was reduced during exercise and post-exercise probably because beta-receptor mediated lipolysis was antagonized.

Adult↗
PubMed1980

Multivariate prognostic index in acute myocardial infarction for individual duration of hospitalization.

To estimate the feasibility of an early and individualized discharge of acute myocardial infarction patients, a new prognostic index was constructed from Cox's regression model for survival analysis. From the first 5 d in the coronary care unit the significant prognostic variables in the index were heart failure (definite objective signs of congestive heart failure and/or definite cardiomegaly and/or pulmonary vascular enlargement on chest x ray in upright position), cardiogenic shock, atrioventricular block, and age. From the index the individual patient's probability of survival up to day 36 after admission could be directly predicted. The more positive the index, the higher was the probability of death. The prognostic efficacy was good, with two unexpected deaths from 149 patients in the lowest risk group. With a selected mortality risk of 5% from the day of discharge until day 30 after admission, 134 patients (52%) could be discharged on day 6. To have the risk of less than or equal to 5% after discharge another 54 patients (21%) would have to stay in the hospital for 24 d. Following this system of early and individualized discharge there were few serious post-discharge complications (one cardiac arrest and one ventricular tachycardia). Reinfarctions could not be predicted. This model could save around 2000 hospitalization days per year in this hospital.

Adult↗
PubMed1980

Immediate haemodynamic and metabolic effects of intravenous labetalol in the exercising forearm.

Dynamic forearm exercise was performed in healthy subjects before and after intravenous labetalol, 1 mg/kg body weight. Labetalol produced a sustained fall in arterial blood pressure. Forearm blood flow decreased by 17.2% partly due to the reduced driving pressure and partly due to an increased vascular resistance. Forearm oxygen uptake decreased by 14.6%, suggesting an increased mechanical efficiency. Lactate release from the exercising forearm decreased by 17.6%. Forearm uptake of glucose and free fatty acids remained unchanged.

Blood Pressure↗
PubMed1980

Sequential haemodynamic effects of labetalol at rest and during exercise in essential hypertension.

The haemodynamic effects of labetalol were studied in patients with essential hypertension after acute and long-term administration. In the acute study 50 mg of labetalol was given i.v. to 10 patients. Eight of them were re-examined after three to four months of oral treatment with labetalol 300 mg t.i.d. Measurements were made at supine rest, after five minutes in the upright position, and after five minutes' supine bicycle exercise at 50 and 100 watt work loads. In the acute study cardiac output was unchanged except at the work load of 100 watt when it decreased 18%. The mean blood pressure decreased under all conditions, 11.6 mm Hg at supine rest, 22.3 mm Hg in the upright position and 15.9 mm Hg and 16.9 mm Hg at the two work loads. Heart rate was unchanged at supine rest, and reduced by 10% in the other situations. Total peripheral resistance was reduced significantly at rest in the supine and upright positions, but not during exercise. Pulmonary artery pressure was unchanged. In the long-term study cardiac output was unchanged except of the heavy work load when it decreased 11%. Mean blood pressure was reduced significantly by 14.6 mm Hg at supine rest, 16.8 mm Hg in the upright position and by 13.9 mm Hg and 13.4 mm Hg, respectively, at the two work loads. Heart rate was reduced significantly in all conditions by 10-14%. Total peripheral resistance decreased significantly at rest, but not during exercise, and pulmonary artery pressure was unchanged.

Blood Pressure↗
PubMed1980

Immediate effects of labetalol on central, splanchnic-hepatic, and forearm haemodynamics during pleasant emotional stress in hypertensive patients.

The effects of intravenous administration of labetalol in a dose of 0.75 mg/kg body weight on central, splanchnic-hepatic and forearm haemodynamics were studied in 8 hypertensive patients resting in the supine position and during pleasant psychic stress induced by practice of a television-game of tennis. In the resting state labetalol caused immediate reduction of arterial blood pressures and of total vascular resistance, whereas heart rate, cardiac output and splanchnic-hepatic and forearm blood flow remained unchanged. After labetalol, the stress-induced increase in heart rate, cardiac output, estimated myocardial oxygen demand and forearm blood flow was significantly reduced, whereas total vascular resistance and splanchnic-hepatic vascular resistance remained unchanged. This is taken to indicate that the alpha-adrenoceptor blocking properties of labetalol may offer haemodynamic advantages as compared to the widely used non-selective beta-adrenoceptor blocking agents in the management of hypertension.

Ethanolamines↗
PubMed1980

Effect of labetalol on plasma catecholamines at rest and during increased sympathetic activity.

Mean arterial blood pressure was decreased by intravenous labetalol in 14 hypertensive patients, resting in the supine position, when standing, during exercise and during psychic stress. Heart rate was unchanged during psychic stress and while resting in the supine position, whereas it fell in the other situations. Plasma noradrenaline increased in all situations after labetalol compared to control studies. Plasma adrenaline only increased when standing and during stress, and there was no correlation between changes in plasma noradrenaline and adrenaline. Blood glucose rose significantly after labetalol in the supine position, whereas it only tended to increase in the other experimental situations. The changes in plasma noradrenaline and blood glucose induced by labetalol are identical to those seen after pure alpha-adrenoceptor blockade. The beta-adrenoceptor blocking property of labetalol may contribute to the higher plasma concentration of noradrenaline when standing and during exercise as this has been found during pure beta-adrenoceptor blockade.

Adult↗
PubMed1980

Multivariate long-term prognostic index from exercise ECG after acute myocardial infarction.

From a symptom-limited bicycle exercise test 3 wk after acute myocardial infarction is 205 patients the prognostic significance for the 1-yr prognosis of the following variables was examined by a multivariate analysis (Cox's model): reasons for stopping, duration of work, maximal heart rate, maximal product heart rate x systolic blood pressure, maximal ST-deviation, time to maximal ST-deviation and ventricular ectopic beats (type and frequency). The reason for stopping was fatigue in 59% and angina pectoris in 15%. 48% exercised up to 6 min and 14% beyond 12 min with median duration of 7 min. The maximal heart rate was over 140/min in 30%. ST-deviations were found in 77%; in most patients below 3 mm. 44% had ventricular ectopic beats during the exercise. The only significant variable was the duration of of work with prognostic index for the 1-yr prognosis SE: SE = 1.21-0.16 x (duration of work). A probability of survival of over 0.95 after 1 yr required a duration of work over 13 min. The observed deaths were in good accordance with the expected with a little overestimation. 75% died from a definite cardial cause. There is a good predictive value for the 1-yr prognosis of the duration of work from an exercise test 3 wk after AMI.

Aged↗
PubMed1979

Cardiovascular and adrenergic effects of cigarette smoking during immediate non-selective and selective beta adrenoceptor blockade in humans.

The cardiovascular and adrenergic responses to cigarette smoking during acute selective and non-selective beta adrenoceptor blockade were studied in seven young healthy volunteers in a double blind cross-over fashion. Heart rate, arterial blood pressure, forearm blood flow and plasma levels of adrenaline and noradrenaline were determined before and during the terminal 5 min period of 15 min smoking test. During smoking, plasma concentrations of adrenaline increased markedly and evenly by approximately 0.3 ng/ml in all three experimental sessions. Plasma concentrations of noradrenaline remained unchanged. Propranolol, a non-selective beta blocker, caused a marked rise in diastolic and mean blood pressure and forearm vascular resistance during smoking. This response was not seen in the control series or after selective beta-1 blockage with atenolol. This difference is attributable to propranolol's blockade of adrenaline's vasodilating effect mediated by beta-2 receptors in the resistance vessels. Furthermore, atenolol attenuated the systolic blood pressure and tachycardiac responses induced by cigarette smoking by comparison with placebo. This study suggests that selective beta-1 blockers are preferable in the management of patients who are habitual smokers.

Adult↗
PubMed1979

Short-term prognostic index in acute myocardial infarction. Multivariate analysis by Cox model.

A new multivariate stepwise linear regression analysis (Cox's model) with survival time as prognostic endpoint was utilized in 281 patients with acute myocardial infarction. From 18 prognostic factors occurring during the first 5 days in the Coronary Care Unit a new prognostic index was calculated for the chance of survival in the first 36 days after admission. The significant prognostic variables were heart failure, cardiogenic shock, atrioventricular block and age. The total group of patients was classified in 6 subgroups with different mean indices and prognosis. There were 2 large groups of patients with relative bad and good prognosis (with and without heart failure). Over half of the patients had no prognostic variables. There was a trend of overestimating the expected deaths. A definite cardiac cause of death was shown by 23 patients (82%). This prognostic index based on the 4 variables can for the individual patient predict the chance of survival, which can be the basis of an individualized duration of hospital stay.

Age Factors↗