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Biomedical subjects

R Sivertsson

Publications and source records attributed to R Sivertsson.

At least 37 records · Page 2Linked to original sources
PubMed1984

Acute haemodynamic effects of carvedilol (BM 14190), a new combined beta-adrenoceptor blocker and precapillary vasodilating agent, in hypertensive patients.

Carvedilol (BM 14190) is a new compound with combined nonselective beta-adrenoceptor blocking activity, devoid of ISA, and a precapillary vasodilating effect. Its acute haemodynamic effects were studied by invasive techniques in 10 patients given 25 mg carvedilol and noninvasively in 10 patients given 25 mg and in 10 given 50 mg orally. All had essential hypertension. In the invasive study intraarterial blood pressure was measured and cardiac output was determined by the dye-dilution method using Cardio-Green as the indicator. Peripheral haemodynamics in all 30 patients were studied in the forearm using strain gauge plethysmography. Measurements were made at rest before and repeatedly for 90 minutes after oral administration of one capsule of 25 mg or 50 mg carvedilol. Significant reductions in the systolic and diastolic blood pressures (p less than 0.05-0.001) were observed in all groups. Cardiac output showed a small, non-significant decrease from 5.81/min to 5.1 l/min. Total peripheral resistance did not change, whereas resistance in the forearm fell by 16% (p less than 0.05). These findings are different from what would have been expected acutely after administration of a pure beta-adrenoceptor blocking agent. They indicate that carvedilol possesses vasodilating activity in addition to its beta-adrenoceptor blocking effect.

Adrenergic beta-Antagonists↗
PubMed1984

Circulatory effects of nitroglycerin ointment (Nitrong) with special reference to venous distensibility.

Nitroglycerin ointment (Nitrong 2%, 5 cm) and an identical placebo ointment were tested in a double-blind crossover study in five healthy volunteers to determine its influence on heart rate, blood pressure, and venous distensibility during supine rest and at 45 degrees tilt. Two hours after administration, a significantly higher venous distensibility was observed with the active ointment than with placebo. There were insignificant changes in heart rate and blood pressure. Three of the five subjects experienced headache for 6 h or more after active ointment.

Adolescent↗
PubMed1983

Treatment of hypertension with beta-blockers with and without intrinsic sympathomimetic activity.

In a randomized double-blind trial 36 patients with essential hypertension were treated with either metoprolol or pindolol for 6 months following a 6-week placebo period. At the end of the placebo period and after 6 weeks and 6 months of active therapy peripheral hemodynamics at rest and during maximal vasodilatation were studied. Exercise heart rate was reduced to the same extent with both metoprolol and pindolol, indicating that the doses used (metoprolol average 179 mg/day; pindolol average 12 mg/day) were equipotent as regards beta-adrenoceptor blocking effect. The antihypertensive effect was identical with both compounds. However, metoprolol caused a significant reduction of heart rate at rest both at 6 weeks and 6 months. With pindolol the reduction in heart rate was not significant at 6 weeks, and it was clearly much less than with metoprolol. On the other hand, no change in calf vascular resistance was seen during metoprolol therapy, whereas a marked and statistically significant reduction was caused by pindolol. Resistance at maximal dilatation in the forearm did not change with metoprolol, but tended to fall with pindolol after 6 weeks and was significantly reduced after 6 months. This indicates that although metoprolol and pindolol have the same antihypertensive potency, the two agents appear to reduce blood pressure through different mechanisms. Thus, cardiac mechanisms seem to play the most important role with metoprolol, whereas pindolol mainly acts by a reduction in vascular resistance. It also seems that treatment with pindolol normalizes the structural arteriolar abnormality present in hypertension as indicated by the reduction in resistance at maximal vasodilation.

Adrenergic beta-Antagonists↗
PubMed1983

Measurement of cardiac stroke volume during cesarean section: a comparison between impedance cardiography and the dye dilution technique.

Simultaneous determination of cardiac stroke volume by impedance cardiography and the dye dilution technique was compared in ten women undergoing elective cesarean section performed under general or epidural anesthesia. The influence of delivery and the anesthetic procedures used on stroke volume determination by the two methods was evaluated and compared. The correlation coefficients for measurements performed before and during anesthesia showed little variation and were largely unchanged after delivery of the child (r = 0.90-0.97). Mean stroke volume determined by impedance cardiography was significantly (P less than 0.001) lower than mean stroke volume calculated from the dye dilution technique. However, there was no significant difference between the mean change in stroke volume determined by the two techniques during serial measurements. Impedance cardiography was found to be a safe, reliable, non-invasive technique for the measurement of changes in stroke volume during cesarean section. The ability of the impedance method to determine changes in stroke volume was unaffected by the anesthetic procedures employed or by delivery of the child.

Anesthesia, Epidural↗
PubMed1983

Measurement of cardiac stroke volume by impedance cardiography in the last trimester of pregnancy.

Simultaneous determination of cardiac stroke volume by impedance cardiography and the dye dilution technique was compared in 10 women during the last trimester of pregnancy. Measurements were performed in different body positions to investigate the influence of body position on stroke volume. The correlation coefficient for all measurements was 0.87. Mean stroke volume determined by impedance cardiography was significantly (p less than 001) lower than mean stroke volume calculated by the dye dilution technique. There was no significant difference between the mean change in stroke volume determined by the two techniques during serial measurements. The reproducibility of individual impedance-determined stroke volumes (6.1 ml) did not differ significantly from individual values obtained by dye dilution (9.3 ml). Maximum mean impedance-determined stroke volume was recorded in the left lateral position (83.8 +/- 4.0 ml). Mean stroke volume was significantly (p less than 0.01) reduced in the supine position (17.9%). A smaller (14.4%) reduction was registered in the right lateral position. These changes in stroke volume according to body position were equally evident by both methods. Impedance cardiography is a safe, reliable, non-invasive technique for the measurement of changes in stroke volume during late pregnancy. The ability of impedance cardiography to determine changes in stroke volume was unaffected by changes in body position.

Adult↗
PubMed1983

Essential hypertension--implications for pathogenesis from repeated haemodynamic investigations in young men with elevated blood pressure.

Repeated invasive haemodynamic studies were performed in young men (18-21 years) with elevated blood pressures and age and sex-matched normotensive controls before military service and five years later as a follow-up study. Patients with high blood pressure initially showed increased cardiac output and increased vascular resistance during maximal vasodilatation. The latter observation suggests arteriolar wall hypertrophy but was restricted to the subgroup of patients with low/normal cardiac output (normokinetic subgroup). In the follow-up study the cardiac output in patients with high blood pressure was no longer increased in comparison with controls and this normalization was restricted to patients previously showing the highest cardiac output (hyperkinetic subgroup). Contrary to the hypothesis this subgroup of patients had not developed significant signs of arteriolar wall hypertrophy although a tendency was present.

Adult↗
PubMed1982

Cardiovascular effect of nicotine chewing gum in healthy non-smokers.

Nicotine chewing gum (Nicorette 4 mg) and an identical placebo gum were administered on different days, in a double-blind cross over fashion, to 4 men, aged 25-52 years, and 4 women, aged 21-49 years, all healthy non-smokers. The subjects chewed the gum for 30 min and heart rate, blood pressure, electrocardiogram, finger tip temperature, calf and hand blood flow and whole blood nicotine levels were measured for 240 min in the supine position, under indirect body heating. 72% -96% of the nicotine was absorbed. Only heart rate showed a significant increase (10%-12%) during the study as compared to placebo. The mean peak nicotine level was 6.5 ng/ml, which occurred at 15-60 min and roughly coincided with the peak heart rate, and then levelled off to around 3 ng/l at 120-240 min. All subjects complained of nausea, dizziness or anxiety to varying degrees. It is concluded that if healthy non-smokers chew Nicorette gum 4 mg by mistake, they would probably suffer more from generally unpleasant symptoms than from any cardiovascular upset.

Adult↗
PubMed1982

Mode of action of beta-adrenoceptor blocking agents in hypertension. A comparison between metoprolol and pindolol with special reference to peripheral vascular effects.

beta-Adrenoceptor blocking drugs are generally recognized as being effective in the treatment of hypertension. The mechanisms whereby these drugs reduce blood pressure are, however, not fully understood. In a double-blind, randomized study either metoprolol, 100--300 mg/day, or pindolol, 5--15 mg/day, was given for 6 months and the effects on blood pressure, heart rate and vascular resistance in the calf and forearm were investigated. Measurements were made at rest, during and after physical exercise, and during postischaemic hyperaemia. Both drugs reduced blood pressure to the same extent both at rest and during and after exercise. Metoprolol reduced heart rate to a greater extent than pindolol at rest and after exercise, whereas no difference was seen during physical exercise. Pindolol reduced the vascular resistance in the calf at rest by 14% (p less than 0.05), whereas metoprolol tended to increase vascular resistance, the difference in effect being highly significant (p less than 0.005). During and after leg exercise, there was no difference in forearm vascular resistance between the two drugs. It may be concluded that pindolol reduced resting blood pressure partly through peripheral vasodilatation. This was probably an effect of beta 2-adrenoceptor stimulation linked to the pronounced intrinsic sympathomimetic activity (ISA) of pindolol. Metoprolol on the other hand, acted mainly through cardiac mechanisms, as suggested by its pronounced reduction of heart rate.

Adult↗
PubMed1982

A hemodynamic study of arteriolar changes in patients with previous malignant hypertension.

Blood flow resistance was studied in two peripheral vascular beds in 15 patients with previous malignant hypertension and in matched groups of patients with "benign" hypertension and control subjects. Both hypertensive groups had significantly higher resistance in the hands (skin vessel bed) at maximal dilatation (2.5 and 2.5 U, respectively) than the normotensive group (1.9 U) (p less than 0.01). This increase indicates structural changes in the arteriolar wall in both hypertensive groups. It indicates a similar degree of adaptation of the vascular changes to the present blood pressure level in both hypertensive groups, although the initial blood pressure had been much higher in the group with previous malignant hypertension than in the group with "benign" hypertension. Different findings were made in the calves (muscle vessel bed), and the most severe changes were found in patients with previous malignant hypertension. Resistance at maximal dilatation was 2.4 U compared to 1.9 U in the group with "benign" hypertension (p less than 0.05) and 1.6 U in the control group (p less than 0.001 and p less than 0.05, respectively).

Adult↗
PubMed1982

Haemodynamic effects of metoprolol and pindolol: a comparison in hypertensive patients.

1 In a double-blind study, 36 patients with essential hypertension were randomly allocated to treatment with either metoprolol, 100--300 mg/day, or pindolol, 5--15 mg/day for 6 months. Haemodynamic investigations were made on three separate occasions. Blood flow in the calves and in the forearm was determined by venous occlusion plethysmography after 6 weeks of placebo, after 6 weeks and again after 6 months of active therapy. 2 Both drugs reduced blood pressure significantly, by 17.1/11.8 mm Hg with metoprolol and 21.9/10.9 mm Hg with pindolol after 6 weeks (P less than 0.005). No further changes were seen after 6 months. 3 Heart rate after 6 weeks was significantly reduced by metoprolol (10.7 +/- 2.4 beats/min, P less than 0.001) but not by pindolol (4.4 +/- 2.3 beats/min, NS). After 6 months a significant reduction was seen also in the pindolol group (5.2 +/- 2.1 beats/min, P less than 0.05). 4 The vascular resistance in the calves at rest was reduced by pindolol (P less than 0.05), whereas resistance tended to increase with metoprolol. 5 Resting vascular resistance in the forearm after 6 months was significantly reduced in the metoprolol group (P less than 0.001) as well as in the pindolol group (P less than 0.02). The increase in forearm vascular resistance seen during leg exercise was not influenced by either drug. 6 Vascular resistance at maximal vasodilatation was unchanged in the calves, but a significant reduction (-17.4 +/- 5.7%, P less than 0.01) in the forearm vascular bed was seen after 6 months of pindolol. No change was observed with metoprolol. 7 It is concluded that pindolol reduces elevated blood pressure partly through peripheral vascular mechanism. Metoprolol, on the other hand, probably acts mainly via central cardiac mechanisms.

Adult↗
PubMed1982

Measurement of stroke volume with impedance cardiography.

Simultaneous determination of stroke volume with impedance cardiography and the dye dilution technique was compared in 11 healthy men before and after exercise. The correlation coefficient for all measurements was 0.82. Mean stroke volume determined by impedance cardiography was significantly (P less than 0.001) lower than mean stroke volume calculated by the dye dilution technique. However, there was no significant difference in the mean change in stroke volume determined by the two techniques during serial measurements. The reproducibility of single impedance-determined stroke volumes (6.9 ml) was not significantly different from single values obtained by dye dilution (7.3 ml). Impedance cardiography was found to be a safe, reliable, non-invasive method for the measurement of changes in stroke volume in healthy individuals before and after exercise. At present, direct estimation of absolute values of stroke volume is not recommended using impedance cardiography. Calibration of the impedance technique against other established techniques in a given application is necessary.

Adult↗
PubMed1982

Penile blood pressure in erectile impotence following cystectomy.

Penile systolic blood pressure and systolic and diastolic brachial blood pressure were measured in 17 men who had undergone cystectomy and prostatectomy for cancer of the bladder. After the operation, 13 patients reported erectile impotence, while 4 retained sexual potency. Comparisons were made with 7 healthy, potent controls. The systolic penile blood pressure was significantly lower and the systolic pressure gradient between brachial and penile pressure was significantly higher in the men with erectile impotence than in the potent men. Reduced penile blood pressure after such operations may arise from vascular trauma. A surgical technique that protects penile blood vessels may conceivably reduce the risk of erectile impotence following cystectomy.

Adult↗