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Biomedical subjects

K Gjesdal

Publications and source records attributed to K Gjesdal.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effects of carvedilol and atenolol on arterial pulse curves (plethysmography) and finger temperature after hand cooling.

OBJECTIVE: In a double-blind, parallel study, the effects of 25 mg carvedilol and 50 mg atenolol on peripheral finger circulation and arterial pulse curve configuration were compared. METHODS: Healthy volunteers (n = 17) were examined at baseline and for 15 min after 60 s of hand cooling in ice-water. Finger temperature and digital plethysmography were recorded each minute from the cooled and the control hands. Measurements were also made before and 2 h after drug administration. RESULTS: Blood pressure declined from 120/86 to 108/74 mm Hg after atenolol (n = 9), and from 122/88 to 108/73 mm Hg after carvedilol (n = 8). In both groups, baseline finger temperature increased slightly after drug, and a more rapid rise in finger temperature was observed after cooling. There was no group difference in the drug effect on finger temperature, except in the first few minutes after cooling, when temperature recovery was greater after carvedilol. Carvedilol reduced the vasoconstrictor response to local cooling (digital plethysmography), compared both to the value before drug and after atenolol. At rest, carvedilol changed the pulse curves (control hand) towards vasodilatation and high compliance, expressed as a mean change in the relative height of the dicrotic notch of -10.3% versus 0.0% after atenolol. CONCLUSION: Future studies should clarify whether the vasoactive profile of carvedilol may translate into reduced occurrence of cold hands and feet amongst patients treated for hypertension.

Adrenergic beta-Antagonists↗
PubMed1996

Mechanisms of tolerance during treatment with nitroglycerin patches for 24 h.

OBJECTIVE: We examined the relationship between tolerance development, counterregulatory responses and arterial vasodilating effects evaluated by digital pulse plethysmography. METHODS: Twenty patients with stable angina pectoris were exercise tested before, after 2 and after 24 h of open nitrate patch treatment. RESULTS: The effects observed after 2 h of treatment on exercise duration, ST-segment depression, blood pressure and heart rate were lost in most individuals after 24 h. In contrast, the effects on the arterial pulse curves persisted after 24 h, with a mean change from baseline of 29%, compared to 33% at 2 h. After 24 h, a significant decrease in haematocrit and an increase in body weight were observed. The haematocrit changes correlated with the loss of clinical efficacy (r = 0.57 for ST-segment depression, and r = 0.54 for exercise duration). CONCLUSION: Clinical nitrate tolerance may be observed despite maintenance of the arterial vasodilating effects, and tolerance is more related to plasma volume expansion as a counterregulatory mechanism.

Administration, Cutaneous↗
PubMed1995

[Radiofrequency ablation of heart arrhythmias. Results in the first 150 patients treated at the Arrhythmia center in Oslo].

The authors review the first 150 patients with cardiac arrhythmias who were treated with radio-frequency ablation at a Norwegian arrhythmia centre. The clinical success rate (either electrophysiological cure or a dramatic reduction in the severity and frequency of the attacks) was 97%. 11 patients were treated for two or more arrhythmias. In 27 patients two, occasionally three, sessions were required to obtain a satisfactory clinical result. Repeat ablation is scheduled for three cases where the treatment was unsuccessful. Among 190 ablations, 13 complications occurred, none of which resulted in permanent sequelae. The time spent on each procedure, and particularly the long time spent on fluoroscopy during the earlier procedures, demonstrates the existence of a learning curve for ablation. This lends support to the authorities' restriction of treatment of arrhythmias by ablation to only two laboratories in a population of four million.

Adolescent↗
PubMed1995

[From action potentials to ECG].

The gap between the action potentials of the myocyte and the ECG is now bridged by knowledge. The author demonstrates how learning the basics of ECG can be founded today upon cellular electrophysiology, thus exchanging the traditional "pattern recognition" training for reasoning. In the present article, this is applied to bundle branch blocks, atrial and ventricular hypertrophy, ischaemia and infarction. Further, the influence of drugs and electrolyte disturbances upon ECG is discussed. Basic knowledge of ECG is essential to avoid confusion when a commercial computer program for interpreting the ECG gives a wrong diagnosis.

Action Potentials↗
PubMed1995

Acute effects of low dose nicotine gum on platelet function in non-smoking hypertensive and normotensive men.

Twenty non-smoking middle-aged men with mild untreated essential hypertension were compared to age-matched controls (n = 22) in a double-blind placebo controlled study. Plasma and urinary concentrations of the platelet-specific protein beta-thromboglobulin (beta-TG), platelet count and mean platelet volume were measured before and after chewing 2 mg nicotine gum. The mean plasma nicotine concentration increased to 4.3 ng/ml in the hypertensive group and to 3.9 ng/ml in the normotensive group after 30 minutes of chewing the nicotine gum. Blood pressure and heart rate increased significantly, but there was no difference between the groups. Venous plasma catecholamine concentrations were unchanged. beta-TG concentrations in plasma and urine were similar in the two groups, and plasma beta-TG levels did not change after nicotine gum in either group. Urinary high molecular weight beta-TG decreased after nicotine compared to placebo. Platelet count and volume increased significantly in the hypertensive group, but not in the normotensive group. The response in platelet count was significantly higher in the hypertensive group. Thus, small amounts of nicotine increase platelet counts more in hypertensive than in normotensive non-smoking men, without inducing the platelet release reaction.

Adult↗
PubMed1995

Physical exercise increases plasma concentrations of nicotine during treatment with a nicotine patch.

The effect of physical exercise on plasma nicotine concentrations was studied in eight healthy subjects treated with a nicotine patch releasing 14 mg 24 h-1. After 11 h of patch application, plasma nicotine concentrations were measured before and after 20 min of moderate bicycle exercise, or 20 min of rest. Mean plasma nicotine concentration increased from 9.8 to 11.0 ng ml-1 (P = 0.015) during physical exercise, and fell non-significantly from 10.5 to 10.2 ng ml-1 during rest. The increase in plasma nicotine concentration during exercise is similar to that observed for transdermal nitroglycerin, and may be related to an exercise-induced increase in blood flow in the patch area.

Administration, Cutaneous↗
PubMed1994

A new isosorbide dinitrate extended-release formulation: pharmacokinetic and clinical parameters in patients with stable angina pectoris.

In a double-blind, cross-over study the acute clinical efficacy and pharmacokinetic profile of a newly developed isosorbide dinitrate extended-release (ISDN-ER) formulation (10 mg immediate release and 60 mg slow release) were examined in eight angina patients. Exercise tests were done 1 h before and 1, 6 and 10 h after acute ISDN or placebo; similar testing was repeated after 14 days of open-labelled treatment. At 1, 6 and 10 h after administration, ISDN-ER significantly reduced the mean ST depression at highest comparable workload (HCWL) by 0.8, 0.6, and 0.6 mm, respectively. Total exercise duration increased significantly by 46, 42 and 72 s. The rate-pressure product at HCWL was not reduced significantly at any time, while digital plethysmography demonstrated a significant effect on arterial pulse curves throughout the 10 h. After 14 days of once-daily treatment, similar or somewhat attenuated clinical effects were observed. Pharmacokinetic measurements showed a first peak of ISDN at 1-2 h and a second peak at 4-5 h. The 5-isosorbide mononitrate (5-ISMN) metabolite peaked at 5-8 h and remained high at 10 h. After 14 days of treatment, the mean plasma concentrations of ISDN and 5-ISMN before drug were 0 and 69 ng.ml-1, respectively. Thus, satisfactory acute clinical efficacy and low nitrate levels during the night were observed. However, long-term clinical efficacy needs to be established in larger, placebo-controlled trials.

Aged↗
PubMed1994

Vitamin E restores endothelium dependent vasodilatation in cholesterol fed rabbits: in vivo measurements by photoplethysmography.

OBJECTIVE: Pulse curve plethysmography was used to examine the effect of vitamin E on endothelium dependent and independent vasodilatation in unanaesthetised cholesterol fed rabbits in vivo. The height of the dicrotic notch was used as an index of general arterial vasodilatation. METHODS: Twenty eight rabbits were divided into three study groups; a control group (group 1, n = 8), a group fed 1% cholesterol (group 2, n = 10), and a group fed 1% cholesterol with the addition of 0.2% vitamin E after four weeks (group 3, n = 10). After six weeks on diet the vasodilator responses to acetylcholine and glyceryl trinitrate were measured by photoplethysmography of the rabbit ear. Recordings were made during light sedation at baseline and during infusion of acetylcholine (1.5, 3.0, 6.0, and 12 micrograms.min-1) and glyceryl trinitrate (3.75, 7.5, and 15.0 micrograms.min-1). In a second set of experiments with control fed rabbits (n = 5), acetylcholine infusions were given before and after infusion of L-nitro-arginine (15 mg). RESULTS: The relative height of the dicrotic notch (which predominantly indicates arterial tone in the larger vessels) was reduced by acetylcholine in a dose dependent manner, but in cholesterol fed rabbits (group 2) this response was significantly decreased. Rabbits receiving concomitant dietary vitamin E responded in a similar manner to controls. The difference was most prominent using acetylcholine at a dose of 3.0 micrograms.min-1, where the mean change from baseline was 11(SEM 4)% in group 2, compared to 31(6)% in group 1 (p = 0.01), and to 26(5)% in group 3 (p = 0.02). Similar differences between the groups were observed for the increase in heart rate during acetylcholine infusions. In contrast, the responses to glyceryl trinitrate were similar in all groups. After infusions of L-nitro-arginine, the responses to acetylcholine were blunted. CONCLUSIONS: Supplementation with vitamin E restored the otherwise reduced vascular response to acetylcholine in cholesterol fed rabbits. Analysis of photoplethysmographic pulse curves is a simple non-invasive method of evaluating arterial vasodilator effects. However, the nature of the measured dilator response needs to be characterised further.

Acetylcholine↗
PubMed1993

[Guidelines for use of amiodarone (Cordarone). A potent anti-arrhythmic agent that may have problematic adverse effects].

The authors discuss the potent antiarrhythmic drug amiodarone, with emphasis on indications, efficacy and side effects. At present the drug can be prescribed only by specialists in internal medicine. In order to monitor the efficacy of the drug and any side effects the patient should preferably be evaluated every three to six months. Use of intravenous amiodarone in hospital is effective in many cases but, so far, documentation on this treatment is limited.

Amiodarone↗
PubMed1993

[The practical benefits of ambulatory continuous ECG recording].

The diagnostic yield from ambulatory continuous ECG recording (Holter ECG) has been evaluated retrospectively in 200 consecutive patients referred from an urban population of 250,000 for arrhythmia diagnosis or evaluation. About half of the patients were in hospital, the other half were ambulatory. In 20/200 (10%) the examination was obviously useful: indication for therapy was documented or arrhythmia and symptoms did not coincide. 53/200 (26.5%) possibly benefited, with qualitative or quantitative observations of clinical interest, and 127 (63.5%) probably did not benefit (no previously unknown findings of importance). Of the 85 patients referred for syncope, six obviously benefited and ten possibly benefited from the examination.

Arrhythmias, Cardiac↗
PubMed1993

Effect of cold pressor test and awareness of hypertension on platelet function in normotensive and hypertensive women.

Plasma beta-thromboglobulin (beta-TG) concentration, reflecting platelet function in vivo, was compared in fertile women with untreated essential hypertension and age-matched normotensives, in two separate studies. In the first study, hypertensives and normotensives were aware of their blood pressure status. Blood was sampled through arterial and venous indwelling catheters, and no difference in beta-TG was found between the groups. Arterial beta-TG was significantly lower than venous concentration (p < or = 0.05). Cold pressor test increased arterial beta-TG significantly in both groups (p < 0.05). In the second study, both women and investigator were unaware of blood pressure status, and beta-TG concentration, platelet count, and mean platelet volume obtained by venipunctures were similar in the hypertensive and normotensive group. Thus, platelet function in vivo seems to be normal in fertile hypertensive women, in contrast to the platelet dysfunction previously reported in hypertensive men. In women, as in men, platelet release occurred during venous catheter blood sampling and during cold pressor test. However, at variance from men, platelet function was not influenced by awareness of blood pressure status in the hypertensive females.

Adult↗
PubMed1992

[Cooperation between regional and central hospitals--how to achieve the best results?].

The authors reviews a recent governmental analysis of cooperation between third-line university clinics and local and central hospitals. The hospitals are owned by the government (mainly by the counties), and the various Acts and regulation permit the central authorities to make decisions on all aspects of highly specialized medicine. The analysis concludes that a limited number of problems should be solved by decision of the central government, but only those where national concerns are involved. The counties within a health region should cooperate within a Regional Health Policy Board, to create plans for flow of patients through the health care system, specified for each field of medicine. When such plans have been approved by the Regional Health Policy Board, each county should be willing to accept them. In the event of local disagreement, the central government should decide.

Health Policy↗
PubMed1992

[Highly specialized medicine. How to assign the tasks?].

Norway has four million inhabitants and five university hospitals, each serving one health region. The authors describe the work of a governmental medical committee, whose mandate is to advise on where to locate the various highly specialized medical services. Important questions have been the relationship between experience and quality, and the desire of each university clinic to be able to provide treatment within its own region for most health problems. Their reasons are concern about research and specialist training, and the preference of patients for treatment near to home. A list of proposed national and over-regional centers for certain treatments has been prepared on the basis of the experts' report and comments from all university clinics. These recommendations have provided a medical basis for later economic and political analyses prior to final decision by the Government. Norwegian legislation permits strong governmental regulation of the highly specialized health services.

Health Planning↗
PubMed1992

The effect of transdermal nitroglycerin on exercise tolerance in relation to patch application time--a meta-analysis.

Disagreeing results have been reported in the many studies on continuous treatment with nitroglycerin patches. The effects on exercise tolerance are partly studied at the end of a 24-hour application period, and partly examined only a few hours after patch renewal. The present meta-analysis estimates the overall efficacy of nitroglycerin patches in trials with and without concomitant antianginal therapy, and investigates if the treatment effect depends on the patch application time. A computed search (MEDLINE) identified 110 publications, of which 17 trials on nitrate patch monotherapy and six trials on combined therapy satisfied the inclusion criteria. Data on "exercise duration" and "ST-segment depression" were converted to a standardized treatment effect size d, and pooled to an overall treatment effect size d+. In tests 2-5 hours after patch renewal, moderate but significant effects of nitrate monotherapy were observed; d+ was 1.20 with regard to "ST-segment depression" and 0.39 with regard to "exercise duration" (both p < 0.0001). In contrast, 24 hours after patch application, the values for d+ were 0.09 (not significant) and 0.36 (p < 0.01), respectively. When adding the results from the six trials on combined therapy, d+ with regard to "exercise duration" was reduced to 0.28 (p < 0.0001) 2-5 hours after renewal and to 0.17 (p = 0.04) after 24 hours. Thus, the efficacy of continuous nitroglycerin patch treatment is moderate but evident during exercise tests 2-5 hours after patch renewal; however, it is reduced after 24 hours of patch application.

Administration, Cutaneous↗
PubMed1992

Heating and cooling of the nitroglycerin patch application area modify the plasma level of nitroglycerin.

19 healthy volunteers wore a nitroglycerin patch releasing 10 mg per 24 h for 2 h. Subsequently, the skin area surrounding the patch was exposed to 15 min of local heating with an infrared bulb (Group A, n = 10), or local cooling with an ice-pack (Group B, n = 9). The patch was protected by an insulating shield (Styrofoam). After 10 min of heating, the median (Walsh) plasma nitroglycerin level increased from 3.1 to 7.6 nmol.l-1. Body temperature remained constant. After 15 min of cooling the median plasma level had dropped from 2.1 to 1.4 nmol.l-1. The results demonstrate that changes in skin temperature may cause extensive short-term changes in the bioavailability of nitroglycerin. Presumably, a subcutaneous or cutaneous reservoir builds up during transdermal treatment, and changes in regional cutaneous blood flow affect the rate of drainage from the reservoir into the systemic circulation.

Administration, Cutaneous↗