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Biomedical subjects

P Omvik

Publications and source records attributed to P Omvik.

At least 91 records · Page 5Linked to original sources
PubMed1988

Nisoldipine. Central haemodynamics at rest and during exercise in essential hypertension: acute and chronic studies.

Calcium blockers may reduce contractility of vascular smooth muscle as well as that of myocardial cells. Therefore, falls in both total peripheral vascular resistance (TPR) and cardiac output (CO) might be responsible for a fall in blood pressure (BP) caused by calcium blockers in essential hypertension. We have studied the acute and chronic haemodynamic effects of nisoldipine (a new calcium blocker) in 19 patients with essential hypertension at rest in the supine and sitting positions and during 100-W dynamic exercise to investigate whether CO might be compromised by acute and chronic calcium blockade. Intra-arterial pressure, CO (by Cardiogreen), stroke volume, heart rate and TPR were measured hourly after the first dose of 10 mg nisoldipine (acute study) and then after 1 year of nisoldipine treatment (mean dose 25 mg; chronic study). The maximal first dose response was seen after 1 h, i.e. a fall in intra-arterial pressure (9%) and TPR (19%) and a reflex rise in heart rate (9%) and CO (12%). The effects levelled off during the next 2 h. After 1 year of treatment there was a more marked reduction in BP: at rest intra-arterial pressure fell (14% supine, 16% sitting) due to fall in TPR (19%) but without significant changes in heart rate or CO; during 100-W exercise, intra-arterial pressure fell (14%) due to reduction in both TPR (7%) and CO (6%). In conclusion, nisoldipine lowers BP by reducing TPR, both acutely and chronically. The initial reflex tachycardia and rise in CO disappear during long-term treatment, probably due to resetting of the baroreceptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Central hemodynamic changes of calcium antagonists at rest and during exercise in essential hypertension.

Since the cardinal hemodynamic disorder in essential hypertension is an increased total peripheral resistance, drugs that can lower resistance without reducing blood flow would be particularly useful. The calcium antagonists seem to fulfill this criterion. The purpose of this work was to study the hemodynamic effects at rest and during exercise of three calcium channel blockers, verapamil, nifedipine, and nisoldipine, in patients with mild to moderate essential hypertension. Fifty-four patients aged 20-64 years with pretreatment diastolic blood pressures of between 95 and 120 mm Hg were studied at rest and during exercise on an ergometer bicycle. Blood pressure was recorded intraarterially and cardiac output was measured by Cardiogreen. After the initial study, 10 patients were treated with verapamil (40-80 mg three times daily), 15 with nifedipine (long-acting form, 20-80 mg daily), and 19 with nisoldipine (10-40 mg daily). After 1 year the hemodynamic study was repeated. The immediate response to the first dose was studied in the patients taking nisoldipine and in 10 patients after taking placebo tablets. Placebo induced no significant changes in central hemodynamics during the first 3 h after tablet intake. The calcium antagonists induced a reduction in blood pressure and in total peripheral resistance (in the order of 10-18%) without any reduction in cardiac index. Reflex tachycardia and an increase in cardiac output were seen in the first 2 h after the first dose of nisoldipine, but after 1 year the heart rate was unchanged compared with the pretreatment rate at rest and during exercise. In contrast, heart rate was reduced on verapamil treatment, particularly during exercise (about 10% of patients), but this was compensated for by an increase in the stroke volume. The hemodynamic profiles of the three calcium channel blockers were slightly different, especially with respect to the heart rate response. Total peripheral resistance was reduced, acutely as well as chronically, and no depression in cardiac pump function was seen, either at rest or during exercise.

Adult↗
PubMed1987

Central hemodynamic effects at rest and during exercise of acute and chronic treatment with nisoldipine in essential hypertension.

The acute and chronic hemodynamic effects of nisoldipine were studied in 19 patients (17 men, 2 women; mean age 43 years) with essential hypertension at rest supine and sitting and during steady state 100 W bicycle exercise. At rest supine, the first dose response (1 h) was reduction of intraarterial (IA) pressure (9%) and total peripheral vascular resistance (TPR; 19%) and rise in heart rate (HR; 9%) and cardiac output (CO; 12%). Thereafter, the effect leveled off: at 3 h, IA pressure, CO, and TPR were reduced 6%, 1%, and 4%, respectively. Similar results were seen at rest and during exercise. After 1 year treatment, the changes were more marked: at rest, IA pressure and TPR fell (16% and 20%, respectively) while stroke volume and CO rose slightly (4% and 6%, respectively). There was no reflex tachycardia. During 100 W exercise, IA pressure fell (14%) due to reduction both in TPR (7%) and CO (6%). Thus, at rest, nisoldipine lowers blood pressure by reduction of TPR both acutely and chronically. The initial rise in CO is lost after long-term therapy. During exercise, falls in both TPR and CO contribute to the hypotensive effect.

Adult↗
PubMed1986

Is sodium restriction effective treatment of borderline and mild essential hypertension? A long-term haemodynamic study at rest and during exercise.

Blood pressure (BP) may fall during moderate sodium restriction in patients with essential hypertension (EH). Few data are available on the haemodynamic changes associated with sodium restriction and exercise data are lacking. We studied the long-term haemodynamic effect of reduced sodium intake in 19 men aged 16-51 years with mild and borderline EH. Cardiac output (CO; by Cardiogreen) and intra-arterial BP were measured at rest and during exercise before and after 9 months therapy. Sodium excretion was reduced by 75 mmol/24 h (36%) from a mean of 209 mmol/24 h and the sodium:potassium (Na:K) ratio fell by 0.75 from 2.17. Intra-arterial pressures fell by 3-5% (P less than 0.05) at rest, both supine and sitting, and during 50, 100 and 150 W bicycle exercise. Body weight and body fluid volumes (isotope dilution) remained unchanged. Haemodynamically, the fall in BP was due to reduction in CO ranging from 7-12% at rest and during exercise, while total peripheral resistance (TPR) rose by 4-10%. Stroke volume and heart rate fell by 2-9%. We conclude that moderate sodium restriction was not an efficient treatment in our patients with borderline and mild EH. The slight reduction in BP was associated with a fall in CO but without reduction of TPR. Thus, the main haemodynamic disturbance of established EH, that is an increase in TPR, was not normalized by 9 months sodium restriction.

Adolescent↗
PubMed1986

Hemodynamic effects at rest and during exercise of long-term sodium restriction in mild essential hypertension.

During moderate sodium restriction for 9 months in 19 men (33 years) with previously untreated mild essential hypertension (EH) sodium excretion fell from 209 to 139 mmol/24 h. Concomitantly intraarterial pressure at rest sitting fell from 145/93 to 138/88 mmHg (5%) and during 100 W exercise from 168/90 to 162/86 mmHg (4%). The fall in BP was due to reduction in cardiac output (5-11% at rest and during exercise) while peripheral vascular resistance was raised (4-10%). Thus, moderate sodium restriction was not very efficient treatment in our patients with mild EH. The main hemodynamic disturbance of established EH--an increase in vascular resistance--was not normalized after 9 months of low salt diet.

Adolescent↗
PubMed1986

Acute and chronic haemodynamic effects of doxazosin in hypertension at rest and during exercise.

The acute and chronic haemodynamic effects of doxazosin were studied in 14 patients (10 males, four females) with essential hypertension, at rest supine and sitting and during 100 W bicycling exercise. Blood pressure (BP) was recorded intra-arterially in the brachial artery, cardiac output (CO) was measured by Cardiogreen and heart rate (HR) by ECG. One hour after injection of doxazosin 0.5-1.0 mg i.v., mean arterial pressure (MAP) was reduced by 8% at rest supine, 12% at rest sitting and 10% at 100 W (all changes statistically significant), associated with a reduction in total peripheral resistance index (TPRI) of 5% at rest supine, 9% at rest sitting (P less than 0.01) and 14% at 100 W (P less than 0.001). HR was slightly increased (5%, NS) and cardiac index (CI) was unchanged during rest and slightly increased during exercise (4%, P less than 0.05). Patients were then given doxazosin capsules (2-16 mg once daily), aiming at a casual BP of less than or equal to 140/90 mmHg without side-effects. Central haemodynamics were restudied after 1 year. After 1 year of doxazosin treatment, MAP was reduced by 13% at rest supine, 16% at rest sitting and 17% at 100 W (all P-values less than 0.001). TPRI was reduced by 19% at rest supine, 20% at rest sitting and 18% at 100 W (all changes statistically significant). CI was increased by 8% at rest supine (P less than 0.05) but was unchanged sitting and at 100 W. It is concluded that doxazosin lowers BP through a reduction in TPRI acutely as well as chronically, without reductions in CO. BP control was maintained over 1 year without side-effects. Thus, doxazosin normalizes central haemodynamics in patients with mild to moderate essential hypertension, both at rest and during exercise.

Administration, Oral↗
PubMed1984

Combined captopril and hydrochlorothiazide therapy in severe hypertension: long-term haemodynamic changes at rest and during exercise.

Captopril is an orally active converting enzyme inhibitor lowering blood pressure (BP) in different types of hypertension. A combination of captopril and a diuretic is often used in the treatment of severe hypertension. We have examined the chronic haemodynamic effect of combined captopril and hydrochlorothiazide treatment at rest and during 50 and 100 W dynamic exercise in 12 patients with severe therapy resistant essential hypertension. Blood pressure was measured intra-arterially before and after a mean treatment period of 8.7 months. Cardiac index (CI) was measured by dye dilution (Cardiogreen) and body fluid volumes by radioisotope dilution techniques. During rest sitting BP was reduced by 31/17 mmHg (15%) from a pretreatment value of 205/119 mmHg. Total peripheral resistance index (TPRI) fell 17% whereas CI, heart rate (HR) and stroke index (SI) did not show any significant changes. The fall in mean arterial pressure (MAP) was slightly less during exercise (12%) and the BP reduction was associated with a fall in CI and SI of 15 and 17%, respectively and no fall in TPRI. No significant changes were observed in body fluid volumes.

Adult↗
PubMed1984

Interstitial colloid osmotic and hydrostatic pressures in human subcutaneous tissue during early stages of heart failure.

Subcutaneous oedema is a common finding in heart failure. However, some patients have reduced cardiac pump function without oedema. The aim of this study was to investigate whether local mechanisms in subcutaneous tissue contribute to oedema prevention. A reduction in interstitial colloid osmotic pressure (pii) and a rise in interstitial fluid hydrostatic pressure (Pi) will both counteract a rise in capillary filtration caused by heart failure. Cardiac catheterization was done in 22 angina pectoris patients without visible oedema. Two days later pii was measured with a wick method and Pi was measured with a wick-in-needle method. Both parameters were measured in subcutaneous tissue on thorax at heart level and on the ankle. Plasma volume was determined by 125I-albumin and extracellular volume measured with 35SO4. Parameters of cardiac pump function ranged from normal to clearly pathological values. Mean pii was 13.0 mmHg on thorax and 8.3 mmHg on the ankle. Pi averaged -2.1 mmHg on thorax and -1.5 mmHg on the ankle. Statistically significant (P less than 0.05) correlations were found between pii on thorax and left ventricular end diastolic pressure (rs -0.40) and pii on thorax and cardiac index (rs 0.42). Pi was positively correlated to right atrial pressure (rs 0.50). Body fluid volumes were normal or moderately reduced. The study shows that a reduction in cardiac pump function is associated with a reduction in pii and a rise in Pi. These changes may help to prevent oedema formation in the early stages of heart failure.

Adult↗
PubMed1984

Hypothesis: discrepancy between intra- and interpopulation studies of the relationship between dietary salt and blood pressure: fact or fiction?

It is a paradox that intra-population studies fail to show significant correlation between sodium excretion and blood pressure while a clear relationship exists in cross-cultural studies. Since daily variation of sodium excretion is high, the discrepancy between the two observations could be due to non-comparable data on sodium excretion. This is a discussion of the hypothesis that the finding of a significant correlation or not between sodium excretion and blood pressure depends on the statistical analysis of the data.

Blood Pressure↗
PubMed1984

Long-term haemodynamic effects of enalapril at rest and during exercise in essential hypertension.

Twelve males with moderately severe essential hypertension (mean arterial pressure [MAP] ranging 113-162 mmHg) were studied at rest supine and sitting and during bicycle exercise (50, 100 and 150 W). Intraarterial blood pressure (BP), and heart rate (HR) were recorded continuously. Cardiac output (CO) was measured by dye dilution (Cardiogreen). After 6-8 months (enalapril dose 10-40 mg daily) patients were restudied. BP fell in all patients, at rest sitting from 184/107 mmHg to 150/87 (-19%) and during 100 W from 223/117 to 194/98 mmHg (p less than 0.001). Pretreatment total peripheral resistance index (TPRI) was greatly increased in all patients and fell from 4137 to 3651 dyn s cm-5 m2 (-16%) (p less than 0.05). No significant changes were seen in CO, HR or stroke volume. No side effects were seen. It is concluded that enalapril reduces BP in patients with moderately severe hypertension at rest and during exercise due to reduction in TPRI without significant changes in CO or HR.

Adult↗
PubMed1984

Long-term haemodynamic effects of enalapril (alone and in combination with hydrochlorothiazide) at rest and during exercise in essential hypertension.

Nineteen patients (12 male and seven female) with essential hypertension (mean arterial pressure ranging from 113-162 mmHg) were studied at rest, supine and sitting, and during bicycle exercise (50, 100 and 150 W). Intra-arterial blood pressure and heart rate were recorded continuously. Cardiac output was measured by dye dilution (Cardiogreen). The patients were treated with enalapril 10-40 mg (mean 33 mg) once-daily; seven patients received in addition 25-50 mg hydrochlorothiazide daily. After 5-13 months (mean 10 months) patients were restudied. Blood pressure fell (P less than 0.001) in all - at rest sitting from 184/108 to 150/89 mmHg (-19%) and during 100 W bicycle exercise from 225/118 to 197/101 mmHg (-13%). Pretreatment total peripheral resistance index (TPRI) was markedly increased and fell at rest sitting from 4087 to 3514 dyn s/cm-5 m2 (-14%) (P less than 0.05). No significant change was seen in cardiac output, heart rate or stroke volume. Overall body weight and body fluid volume (isotope dilution technique) remained unchanged, but in the subgroup receiving enalapril + hydrochlorothiazide, blood volume fell by 12% (P less than 0.01). No side-effects were seen. In conclusion, enalapril monotherapy reduces blood pressure in two-thirds of patients with moderately severe essential hypertension at rest and during exercise, associated with a significant reduction in TPRI. One-third of patients require a diuretic in addition to enalapril. In this subgroup the reduction in TPRI was about twice the reduction seen during enalapril treatment alone, and there was a fall in blood volume.

Adult↗
PubMed1983

Haemodynamic effects of nifedipine in essential hypertension at rest and during exercise.

Fifteen males with previously untreated essential hypertension in WHO stage I, aged 20-64 years were studied on an outpatient basis. Oxygen consumption, heart rate, cardiac in a in a supine and sitting position and during steady state work at 50, 100 and 150 W. Following the haemodynamic study, nifedipine (long-acting form) 40-80 mg daily was given as the sole drug for 3-12 months (mean 11 months) whereupon the haemodynamic study was repeated. Systolic, diastolic and mean arterial pressures fell about 17% at rest supine and sitting and from 15 to 10% at the three different workloads (P less than 0.001). All but one patient demonstrated a fall in mean arterial pressure of 10 mmHg or more. The fall in pressure was associated with a statistically significant (P less than 0.05) reduction in total peripheral resistance (17% during rest and 10 to 16% during exercise). There were no statistically significant changes in oxygen consumption, heart rate, cardiac index or stroke index.

Adult↗