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Biomedical subjects

P Omvik

Publications and source records attributed to P Omvik.

At least 73 records · Page 4Linked to original sources
PubMed1991

Acute and chronic hemodynamic effects of drugs with different actions on adrenergic receptors: a comparison between alpha blockers and different types of beta blockers with and without vasodilating effect.

The regulation of vascular resistance, cardiac output, and thus blood pressure can be influenced by antihypertensive drugs acting at central and peripheral adrenergic receptors. The results presented here are from acute or chronic studies in 205 patients with mild or moderately severe essential hypertension: beta blockers (N = 101); alpha blockers (N = 36); a separate alpha- + beta-blocker combination or the combination agent labetalol (N = 37); prizidilol, a beta-blocker/vasodilator (N = 14); and dilevalol, a beta blocker/beta 2-stimulator (N = 17). Beta blockers without strong intrinsic sympathomimetic activity reduce heart rate and cardiac output immediately, but due to a reflex increase in total peripheral resistance index, blood pressure is unchanged or only slightly reduced. During chronic use, total peripheral resistance drops towards pretreatment level and pressure falls. Beta blockers with strong intrinsic sympathomimetic activity do not reduce heart rate or cardiac output at rest when sympathetic tone is low. During exercise, heart rate and cardiac output are reduced, but less than with conventional beta blockers, and resistance is unchanged or slightly reduced. An acute and chronic reduction in blood pressure can be produced by alpha-adrenergic receptor blockers (prazosin, doxazosin, trimazosin), and in these cases the fall occurs via a reduction in total peripheral resistance index without reflex tachycardia. These drugs tend to increase exercise stroke volume and cardiac output during chronic treatment. Free combinations of beta and alpha blockers or the use of the fixed combination drug, labetalol, induce marked reductions in blood pressure at rest and during exercise, mainly through a reduction in total peripheral resistance index. During chronic treatment, exercise stroke volume and cardiac output are well maintained. In acute studies with dilevalol, systolic blood pressure, diastolic blood pressure, and mean arterial pressure were reduced (p less than 0.001) within 1 hour in 17 males with essential hypertension (WHO stage I) who received 200-400 mg oral dilevalol. The reduction in MAP was around 16-17% and was associated with an immediate fall in the total peripheral resistance index of the same magnitude (14%, p less than 0.001) after 1 hour at rest. There were no significant changes in heart rate or cardiac index.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1991

Acute haemodynamic effects of carvedilol in essential hypertension at rest and during exercise.

The acute haemodynamic effect of carvedilol, a new non-selective beta-receptor blocker with vasodilating effect, was examined at rest supine and sitting and during 100 W bicycle exercise in 18 patients (mean age 44 years) with essential hypertension. Intra-arterial blood pressure and heart rate were recorded continuously. Cardiac output was measured by dye dilution (Cardiogreen). Two h after the first oral dose (12.5-25 mg) of carvedilol, blood pressure was reduced in all patients sitting at rest, from 176/110 to 153/101 mmHg (P less than 0.001), associated with a reduction in cardiac index (16%; P less than 0.001) while total peripheral resistance remained unchanged or was slightly reduced. When sitting up after 2 h supine rest two patients had hypotensive reactions (excessive blood pressure drop; cold, pale, sweating skin) which disappeared after lying down with elevation of the legs and light physical exercise. The fall in cardiac index was due to reduction both in heart rate (8%, P less than 0.001) and stroke index (9%; P less than 0.01). During exercise the reduction in cardiac output was less (6%; P less than 0.05) while a clear reduction (6%; P less than 0.01) was seen in total peripheral resistance. This acute haemodynamic response is different from that seen immediately after conventional beta-blockers when total peripheral resistance always increases.

Administration, Oral↗
PubMed1991

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

Amlodipine administered once daily (5-10 mg) lowered blood pressure and reduced total peripheral resistance in patients with mild-to-severe essential hypertension without any reflex tachycardia. Heart pump function was maintained at rest and during exercise with a trend towards an increase in cardiac and stroke index. Amlodipine was effective and well tolerated in both young and elderly hypertensive patients with no reports of unpleasant vasodilator-related side effects.

Adult↗
PubMed1990

Comparison of long-term hemodynamic effects at rest and during exercise of lisinopril plus sodium restriction versus hydrochlorothiazide in essential hypertension.

To investigate whether sodium restriction might replace thiazides in promoting blood pressure (BP) reduction by angiotensin-converting enzyme inhibitors, the long-term hemodynamic effect of lisinopril plus sodium restriction versus lisinopril plus hydrochlorothiazide was compared at rest and during dynamic exercise in 2 groups of essential hypertensive patients. Mean pretreatment intraarterial BP at rest sitting was 177/107 mm Hg. The patients were randomly allocated to lisinopril combined with either low salt diet (low salt group, n = 13) or hydrochlorothiazide (diuretic group, n = 12). After 1 year of treatment the mean dose of lisinopril was 25 mg in both groups. In the low salt group sodium excretion was reduced from 188 to 129 mmol/24 hours (p less than 0.01). In the diuretic group sodium excretion was unchanged with a mean dose of hydrochlorothiazide of 19 mg. BP was reduced (p less than 0.001) in both groups: at rest 16 and 21% and during exercise 10 and 13% in the low salt and the diuretic groups, respectively. Total peripheral resistance was reduced (p less than 0.05) in both groups: at rest 14 and 7% and during exercise 8 and 5% in the low salt and the diuretic groups, respectively. Overall cardiac output was reduced (p less than 0.05) in the diuretic group but remained unchanged in the low salt group. Thus, lisinopril--either in combination with a diuretic or sodium restriction--induces marked reduction in BP due to decreases in peripheral vascular resistance both at rest and during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1990

Assessment of four ambulatory blood pressure monitors and measurements by clinicians versus intraarterial blood pressure at rest and during exercise.

The accuracy of 4 different ambulatory blood pressure (BP) monitors was assessed by comparing them to simultaneous intraarterial BP (contralateral brachial artery) during rest, isometric and dynamic (bicycle) exercise in 48 hypertensive patients undergoing invasive hemodynamic evaluation. The differences between the intraarterially determined BP and values obtained by the various monitors were then compared to differences between BP measured directly and by 2 clinicians using a standard mercury column in 10 additional hypertensive patients. The monitors studied were the Accutracker II (auscultatory with mandatory electrocardiographic gating), Colin ABPM 630 (auscultatory or oscillometric), Del Mar Pressurometer IV (auscultatory with optional electrocardiographic gating) and SpaceLabs 90202 (oscillometric). During rest, the differences between intraarterially and clinician-determined systolic and diastolic BP were 4 +/- 8 and -4 +/- 6 mm Hg, respectively. The Accutracker II and Colin ABPM 630 using the auscultatory method showed less disparity and closer limits of agreement (2 standard deviations of the mean difference) with intraarterial BP than the clinicians' measurements, whereas the other units showed similar or greater limits of agreement. During both isometric and dynamic exercise, mean BP differences between intraarterial and clinician determinations were similar to those at rest but the limits of agreement increased. The limits of agreement between intraarterial and monitor-derived BP also increased during exercise compared to differences observed at rest. The Accutracker II and Colin ABPM 630 using the auscultatory method had limits of agreement with intraarterial BP that were either similar to or less than the clinician's, whereas the Colin monitor using the oscillometric method and the Del Mar Pressurometer IV showed greater disparity.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure Determination↗
PubMed1990

The role of multiple action agents in hypertension.

A 20-year follow-up study of central hemodynamics in essential hypertension at rest and during exercise in 61 men with uncomplicated essential hypertension has clearly shown that hemodynamic disturbances depend on the age of the subjects and the severity of the hypertensive state and that a shift in the hemodynamic alterations take place over time. During 10- and 20-year follow-up, central hemodynamics changed towards a low cardiac-index (CI)-high total peripheral-resistance index (TPRI) pattern. With increasing age there was a gradual reduction in CI as well as stroke index (SI). The arteriovenous oxygen difference increased, particularly during exercise. The 20-year treatment with conventional drugs (beta-blockers and/or diuretics) did not prevent a marked increase in TPRI and a marked reduction in CI and SI in subjects initially 40-49 years of age. In recent years, beta-blockers with vasodilating activity have been introduced in the treatment of hypertension (labetalol, prizidilol, dilevalol and carvedilol). The hemodynamic effects of these compounds clearly differ from the changes induced during acute and chronic conventional beta-blocking treatment. In contrast to usual beta-blockers, these drugs reduce TPRI acutely and the reductions they produce in heart rate (HR) and CI are considerably lower. Our long-term data on labetalol (n = 15), prizidilol (n = 15) and dilevalol (n = 17) indicate a persistent reduction in TPRI and little or no decrease in exercise CI. Long-term data on carvedilol are not yet available. Approximately 70% of patients with mild to moderately severe essential hypertension achieved normal blood pressure during chronic treatment on beta-blockers with vasodilating activity.

Adrenergic beta-Antagonists↗
PubMed1990

The initial hemodynamic response to newer antihypertensive agents at rest and during exercise: review of visacor, doxazosin, nisoldipine, tiapamil, perindoprilat, pinacidil, dilevalol, and carvedilol.

Antihypertensive drugs may lower blood pressure through very different mechanisms, initially as well as during chronic use. This article is a review of the immediate hemodynamic changes induced by a beta blocker (visacor), an alpha-receptor blocker (doxazosin), two calcium antagonists (tiapamil and nisoldipine), an angiotensin-converting enzyme inhibitor (perindoprilat), two double-acting compounds (dilevalol and carvedilol), and placebo studied in 126 patients with mild to moderately severe essential hypertension. The patient populations of the different treatment groups were comparable. The invasive hemodynamic technique, including intraarterial blood pressure (BP) recording and measurements of cardiac output by cardiogreen, was the same in all studies. All antihypertensive compounds examined induced a rapid reduction in blood pressure both at rest and during exercise, while no significant changes occurred in the placebo group. This review shows the scope of hemodynamic responses, ranging from peripheral vasodilation to a reduction of heart rate and blood flow. Furthermore, different counterregulatory effects blunting the immediate BP reduction are demonstrated.

Adult↗
PubMed1990

Magnetic resonance imaging and cine computerized tomography as future tools for cardiac output measurement.

The new imaging methods, cine computerized tomography (cine-CT) and magnetic resonance imaging (MRI), are reviewed as tools for cardiac output (CO) measurement. Both modalities provide accurate and highly reproducible measurements of stroke volume and CO at rest. The methods are less applicable during heavy physical exercise. Because of cost and lack of equipment the methods are not practical for measurements of CO alone in the foreseeable future. However, cine-CT and MRI may be of value for CO measurements when additional characteristics, such as wall motion, myocardial structure and tissue perfusion, need to be assessed.

Cardiac Output↗
PubMed1990

Effect of long-term diltiazem treatment on central haemodynamics and exercise endurance in essential hypertension.

The effects of long-term treatment with diltiazem on blood pressure, central haemodynamics and exercise endurance were studied in 16 men (mean age 52 years) with essential hypertension. Intra-arterial pressure and heart rate (HR) were monitored continuously. Cardiac output (CO) was measured by Cardiogreen at rest (supine and sitting) and during 50 W, 100 W and 150 W bicycle exercise. Haemodynamic measurements were repeated after continuous bicycling at 150 W for 20 min or until exhaustion. After 1 year on diltiazem (mean daily dose 278 mg) intra-arterial pressure was reduced (P less than 0.001) in all situations (at rest sitting from 183/108 mmHg to 157/92 mmHg (14%] due to reduction in total peripheral resistance. HR was reduced at rest (7%) and during exercise (10%). Stroke volume tended to increase while CO was unchanged. Exercise time at constant workload increased by 25%. After a peak level, intra-arterial pressure fell by 3% to 5% (P less than 0.05) due to a decrease in total peripheral resistance both before and during diltiazem treatment. Stroke volume and CO remained unchanged during endurance exercise while HR showed a small increase. Thus, there was no reduction in the overall cardiac pump function after long-term diltiazem treatment, and blood flow during exercise was maintained.

Body Weight↗
PubMed1990

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

The long-term haemodynamic responses to amlodipine, a new long-acting calcium antagonist, were studied both at rest and during exercise in 18 patients (mean age 43 years) with essential hypertension. Blood pressure was measured intra-arterially, cardiac output by dye dilution and heart rate by electrocardiogram. After 11 months of treatment with 5-10 mg amlodipine once daily (mean dose 9 mg/day), mean arterial pressure was reduced by 14% sitting at rest. The reduction in blood pressure was associated with a marked reduction in the total peripheral resistance index (TPRI) of 19% (P less than 0.001). Similar responses were seen supine at rest and during 50W, 100W and 150W bicycle exercise. No significant changes were seen in heart rate. There was a slight increase in stroke index, and cardiac index was preserved at rest and during exercise with a slight trend towards an increase. In 10 of the patients, blood pressure was monitored by a portable blood pressure recorder (Accutracker II, Suntech Medical instruments, Raleigh, North Carolina, USA). Blood pressure was well controlled throughout the full 24 h period after one daily dose. In conclusion, amlodipine exerts a clear antihypertensive effect, both at rest and during exercise, through reduction in the TPRI and without a fall in cardiac pump function. No changes in heart rate were seen and there was no tendency for a reduction in the stroke index during 8 min of exercise at 150 W; on the contrary there was a trend towards an increase. The incidence of side-effects was low (ankle oedema in two patients).

Amlodipine↗
PubMed1990

Chronic hemodynamic effects of tiapamil and felodipine in essential hypertension at rest and during exercise.

Sixteen men with previously untreated diastolic blood pressure of 100-120 mm Hg were studied hemodynamically at rest supine and sitting and during a 100 W bicycle exercise. Blood pressure (BP) was recorded intra-arterially, and cardiac output (CO) by the dye-dilution method. After initial study, patients were treated with tiapamil in increasing doses (300-600 mg b.i.d., with a mean daily dose of 980 mg). The patients were restudied and then changed to felodipine (5-10 mg b.i.d., with a mean daily dose of 15 mg). Casual (cuff) BP at rest sitting was as follows: end placebo, 166/105 mm Hg; 1 year of tiapamil, 148/92 mm Hg; 1 year of felodipine, 139/86 mm Hg. Pretreatment hemodynamic results at rest sitting were as follows: BP, 169/105 mm Hg; MAP, 129 mm Hg; cardiac index (CI), 2.43 L/min/m2; total peripheral resistance index (TPRI), 4,305 dyn s/cm-5/m2. Both drugs reduced systolic (SAP), diastolic (DAP), and mean (MAP) arterial pressure significantly in all situations. BP reduction seemed to be more pronounced on felodipine than on tiapamil. Felodipine reduced MAP by 15% at rest supine, 14% at rest sitting, and 11% during exercise. The BP reduction was entirely due to reduction in TPRI (15, 16, and 13%, respectively). CI as well as stroke index (SI) and heart rate (HR) were unchanged. Tiapamil did not reduce TPRI significantly and the fall in BP was due to a combination fall in TPRI and CI.

Adult↗
PubMed1990

[Treatment of hypertension using angiotensin-converting enzyme inhibitors].

Angiotensin conversion enzyme inhibitors (ACE inhibitors) comprise a relatively new group of potent antihypertensives. They are today among the most used preparations for reducing blood pressure. ACE inhibitors may be used for treatment of almost all forms and degrees of hypertension. By reason of the reduction of the resistance in the peripheral vessels the blood pressure drops by 12-20 per cent, both at rest and during muscular effort, without diminution of the heart's pump function. The autonomic reflexes are unchanged and the circulation in the kidneys and the brain is retained. ACE inhibition does not result in fluid retention. In adequate doses the drugs are tolerated and give few side-effects provided that the patient is not dehydrated.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1989

[Patient flow at a medical intensive care unit].

Intensive care units have been established in all somatic hospitals in Norway over the last two decades. In order to examine the use of these units in a medical department the group of patients admitted to the unit at Haukeland hospital during a six month period was analyzed. The flow of patients is twice that found in the regular medical wards. The dominating reason for admittance is heart disease. The overall mortality of the patients in these units is high. However, it is probable that it may be possible to define groups of patients, who without reduction of medical security, could be treated in regular and less costly medical wards.

Humans↗
PubMed1989

Acute and long-term hemodynamic effects of tiapamil at rest and during exercise in essential hypertension.

The first dose and long-term hemodynamic responses to tiapamil--an aralkylamine calcium-channel blocker--were studied both at rest and during exercise in 18 male patients (mean age, 45 years) with essential hypertension (EH). Blood pressure (BP) was measured intra-arterially, cardiac output (CO) was measured by dye dilution and heart rate (HR) was measured by electrocardiogram. One hour after the first oral dose of 600 mg tiapamil, mean arterial pressure (MAP) fell 14%. Total peripheral resistance (TPR) fell 21%, while HR and CO increased 7% and 11%, respectively. Thereafter the effects leveled off. After 11 months of chronic tiapamil therapy (mean dose 980 mg per day), MAP was reduced 11% at rest sitting. The reduction in BP was associated with a modest reduction in TPR. Similar responses were seen at rest supine and during 100-W bicycle exercise. A small reduction was seen in HR while CO was preserved. In conclusion, tiapamil exerts a moderate antihypertensive effect, both at rest and during exercise, through reduction of TPR without a fall in heart pump function. The long-term hemodynamic changes are rather similar to those of verapamil.

Adult↗
PubMed1989

Acute haemodynamic effects of perindoprilat in essential hypertension at rest and during exercise.

The acute haemodynamic effect of perindoprilat was examined at rest, supine and sitting, and during 100 W bicycle exercise in 12 patients (mean age 42 years) with essential hypertension. Intra-arterial blood pressure and the heart rate were recorded continuously. Cardiac output was measured by dye dilution (Cardiogreen) and blood volume was determined by radio-iodinated (125I) human serum albumin. Two hours after a slow (3 min) intravenous injection of perindoprilat, blood pressure was reduced in all patients (P less than 0.01)--at rest sitting from 175/108 to 153/97 mmHg (11%)--because of reduction in total peripheral resistance index (f = 2.63; P less than 0.05). Only minor changes were seen in the heart rate, stroke index and cardiac output. The fall in blood pressure was significantly (P less than 0.05) correlated with blood volume (r = 0.65) and pretreatment total peripheral resistance index (r = 0.59).

Adult↗
PubMed1989

Clinical evaluation of the Accutracker II ambulatory blood pressure monitor: assessment of performance in two countries and comparison with sphygmomanometry and intra-arterial blood pressure at rest and during exercise.

In order to assess the Accutracker II (Suntech Medical Instruments, Raleigh, North Carolina, USA), a relatively new ambulatory blood pressure (BP) monitor, versus standard forms of BP measurement, we compared same- and contralateral-arm measurements made, via a t-tube connected to a mercury column sphygmomanometer, by two clinicians using a teaching stethoscope and by intra-arterial recordings. Average systolic BP values obtained using the Accutracker II were similar to both the mercury column and intra-arterial determinations, but average diastolic BP values were lower than both the average mercury column (2.8 +/- 4.2 mmHg, P less than 0.001) and intra-arterial measurements (2.0 +/- 4.7 mmHg, P less than 0.02). During isometric exercise and 100-watt bicycle exercise, there were greater limits of agreement for the differences in BP between the Accutracker II and the intra-arterial transducer than were observed for the resting measurements, but these differences were no greater than those observed between intra-arterial and clinician-determined BP measurements. The clinical performance of the Accutracker II was assessed using 119 hypertensive subjects (84 in Norway and 35 in the USA) who wore the monitor for 24 h. While there was good-to-excellent data return in both countries, there were significantly less error codes secondary to excessive arm motion observed in Norway. Our data demonstrate that the Accutracker II is quite accurate compared with both the mercury column and intra-arterial methods of measuring BP, and performs well during 24 h outpatient activities. Our findings also indicate certain geographical differences which may be important in the performance of ambulatory BP-monitoring studies.

Adolescent↗
PubMed1988

Comparison of the hemodynamic effects of five calcium channel blockers at rest and during exercise in essential hypertension.

Dihydropyridine and verapamil-like calcium channel blockers reduce blood pressure (BP) in essential hypertension (EH) but have different effects on heart rate (HR) at rest. This study compares the HR and hemodynamic responses to exercise of long-term treatment with nifedipine, nisoldipine, verapamil, tiapamil and diltiazem in five groups of patients with mild and moderate EH (diastolic BP ranging 100-120 mmHg). In a total of 76 patients (mean age 43 years) BP was measured intraarterially, cardiac output by dye dilution (Cardiogreen) and HR by electrocardiogram. Acutely HR and cardiac index (CI) rose (9 and 12%) while BP and total peripheral resistance index (TPRI) were reduced (9 and 19%). After one year calcium channel blockade intraarterial pressure at rest sitting fell from 172/105 to 150/91 mmHg (13%) and at 100 W exercise from 205/109 to 188/97 mmHg (10%). HR remained unchanged in the dihydropyridine groups (range +/- 3%) in all situations while it invariably fell (range 3 to 15%) in the groups treated with verapamil-like calcium blockers. The fall in HR was greater during exercise than at rest (mean 10% vs 6%). With these drugs stroke volume (SV) tended to increase (range 1 to 10%) while it remained unchanged in the dihydropyridine groups. Only minor changes were seen in CO. In all groups the TPRI fell, averaging 15% at rest and during exercise. Thus, the verapamil-like calcium blockers induce a negative chronotropic effect that is enhanced during work, but the cardiac pump function is preserved by a compensatory increase in SI. Independent on the cardiac responses both groups of calcium blockers lower BP by peripheral vasodilatation both at rest and during exercise.

Blood Pressure↗