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Biomedical subjects

R Ekroth

Publications and source records attributed to R Ekroth.

At least 73 records · Page 4Linked to original sources
PubMed1985

Haemodynamic effects of low and high doses of insulin during beta receptor blockade in dogs.

Haemodynamic effects of small and high doses of insulin during beta receptor blockade were studied in nine dogs. Beta receptor blockade was induced by 0.5 mg/kg propranolol and caused depression of cardiac performance with a significant increase in left ventricular end-diastolic pressure (LVEDP) and a significant decrease in heart rate; maximum rate of left ventricular (LV) pressure rise (LVdP/dtmax), stroke volume and cardiac output. At 15 min, after beta receptor blockade, a bolus injection of 0.5 IU/kg of insulin, free of glucagon and calcium, was given followed by a continuous infusion of 0.5 IU/kg/h. After 30 min another bolus dose of 300 IU insulin was injected. Glucose and potassium were given to maintain physiological levels of these factors. Five minutes after a low dose of insulin there was a significant decrease in LVEDP (P less than 0.01), and a significant increase in LVdP/dtmax (P less than 0.01), in stroke volume (P less than 0.01) and in cardiac output (P less than 0.01). The other haemodynamic variables were not significantly changed. Administration of a high dose of insulin further, significantly, improved performance of the beta receptor blocked heart and caused a significant reduction in total peripheral resistance. In conclusion, insulin exerts inotropic and vasodilator effects which are dose-dependent and not related to adrenergic mechanisms.

Animals↗
PubMed1985

Metabolic effects of low and high doses of insulin during beta-receptor blockade in dogs.

Metabolic effects of low and high doses of insulin during beta-receptor blockade were studied in eight dogs. Beta-receptor blockade was induced by 0.5 mg/kg propranolol which caused depression of heart performance. This was accompanied by a significant reduction in myocardial blood-flow and oxygen consumption. There was also a significant reduction in arterial concentrations and myocardial uptake of free fatty acids, while arterial concentrations and myocardial uptake of glucose and lactate were not significantly changed. Fifteen minutes after beta receptor blockade, an intravenous (i.v.) bolus injection of 0.5 IU/kg, of insulin, free of glucagon and calcium, was given followed by a continuous infusion of 0.5 IU/kg/h. Glucose and potassium were given to maintain constant levels of these factors. After 30 min another bolus dose of 300 IU insulin was injected. Thirty minutes after a low dose of insulin, a significant increase in heart performance was recorded at unaltered myocardial oxygen consumption. Arterial concentrations of free fatty acids were significantly reduced while levels of glucose and lactate were unchanged. Myocardial uptake of glucose increased significantly while uptake of lactate and free fatty acids was unchanged. After a high dose of insulin there was a considerable improvement in heart performance. Myocardial blood-flow and oxygen consumption were not changed, nor were there alterations in arterial concentrations and myocardial uptake of glucose, lactate and free fatty acids. It is concluded that, during beta-receptor blockade high doses of insulin improve the mechanical performance of the heart through mechanisms that are independent of insulin's effects on substrate metabolism.

Animals↗
PubMed1984

Electrocardiographic changes and their relation to serum enzyme activity after heart surgery.

In 80 patients who underwent heart surgery the incidence of electrocardiographic (ECG) changes after the operation was analysed. A precordial grid containing 24 leads and leads II, III and aVF was used. Electrocardiographic measurements were taken the day before the operation and again 5 days after the operation. New Q-waves were observed in 2 patients (2.5%) in the 24 precordial leads, in 2 patients in leads II, III and aVF, and in one patient in both precordial leads and leads II, III and aVF. New T-wave inversions were observed in 20 patients (25%) in the 24 precordial leads, in 5 patients (6%) in leads II, III and aVF, and in 3 patients in both precordial leads and leads II, III and aVF. A similar serum enzyme activity was observed both in patients developing Q-waves as well as T-wave inversions compared with cases in whom ECG changes did not appear.

Adult↗
PubMed1984

Haemodynamic effects of a single large dose of insulin in open heart surgery.

The haemodynamic effects of a single dose of 0.35, 1.5 or 7.5 IU fast acting insulin X kg bw-1 were studied in 24 patients undergoing aortocoronary bypass grafting. No inotropic drugs were used. Blood glucose was measured using a continuous blood glucose monitoring system, and was kept at the preinsulin level by administration of a 40% glucose solution. Injection of 0.35 or 1.5 IU X kg bw-1 of insulin did not have significant haemodynamic effects. Injection of 7.5 IU X kg bw-1 of insulin resulted in significant changes in cardiac index (+20.8%) and in total peripheral resistance (-13.9%) within 2 min. After 10 min a reduction of 16.8% was found in the diastolic pulmonary artery pressure. These haemodynamic effects occurred before glucose had been infused. The arterial pressure and the heart rate were unaffected. It is concluded that the injection of 7.5 IU X kg bw-1 of insulin results in an increase in cardiac index in patients who have undergone open heart surgery. The effects are not primarily related to stimulation of glycolysis.

Adult↗
PubMed1983

Influence of noradrenaline and temperature on the isolated perfused rat heart.

Myocardial protection during open heart surgery is achieved by general cooling and cold cardioplegia. However sympathetic activation during the operation causes raised circulating catecholamine levels that might negatively influence the myocardial metabolism. Moreover, local liberation of catecholamines, in "poorly perfused' regions of the myocardium in patients with ischemic heart disease, might occur. In respect of these problems, we studied the influence of noradrenaline at different temperatures on the isolated perfused rat heart. The temperatures chosen were: 10, 20, 32, 37 and 39 degrees C. The results show clearcut adverse effect of noradrenaline at 32 degrees and higher, on metabolism and hemodynamic performance. At lower temperatures there still seem to be an adverse effect of noradrenaline although not statistically significant. The results of this study indicates the importance of presurgical myocardial protection especially of badly perfused myocardial areas. Such protection could be accomplished by beta-blockade and/or loading of the myocardium with glycogen by glucose-insulin-potassium infusion.

Animals↗
PubMed1983

The calcium paradox and its protection by hypothermia in human myocardium.

The 'calcium paradox', i.e. irreversible loss of mechanical and electrical activity after a few minutes Ca2+-free perfusion and subsequent reperfusion with Ca2+-containing medium, was originally demonstrated in rat heart and later in other homoiotherms. It was absent in poikilotherms. The present paper describes the effect of Ca2+-free superfusion on human myocardium at normo- and hypothermia using isometrically mounted, stimulated strips from auricular tissue excised during cardiac surgery. The experiments (including equilibration period) were performed at 37 degrees C, 30 degrees or 25 degrees C. When Ca2+-free and EGTA-containing solution was introduced the force decline started immediately. After 10 min Ca2+-containing medium was reintroduced. Force recovery within 40 min was at 37 degrees C 16% and at 30 degrees C 28% of initial force value. Force recovery in 25 degrees C group was substantially better. Contracture which occurred when Ca2+-containing solution was reintroduced was very strong at 37 degrees C (+ 102%) and weaker at lower temperatures (30 degrees C +48% and 25 degrees C +17%). The extent of loss of mechanical activity and of contracture following the period of Ca2+-free superfusion give evidence that calcium paradox can be provoked in human myocardium and can be prevented by hypothermia.

Calcium↗
PubMed1983

Myocardial protective effect of maintained beta-blockade in aorto-coronary bypass surgery.

Twenty-nine patients were randomly allocated to two groups before undergoing aorto-coronary bypass surgery. In one group the beta-blocking medication was withdrawn three days preoperatively, and in the other group it was maintained. The patients in the latter group were additionally given 100 mg metoprolol per os two hours before surgery. The degree of myocardial injury, as judged from cumulated activity of S-CK B, was less when the beta-blockade was maintained.

Adrenergic beta-Antagonists↗
PubMed1982

Insulin sensitivity and glucose uptake in the course of surgical treatment for valvular aortic stenosis.

The dose-response relationship between plasma insulin and systemic glucose uptake was studied before, one hour after and 6 months after valvular surgery in 11 patients with valvular aortic stenosis. The immediate effect of valvular surgery was a dramatic rightward shift of the dose-response curve and a decrease in glucose uptake at peak insulin activity. From a comparison between the preoperative and the 6-month postoperative dose-response curves it is concluded that the patients had adapted metabolically to the preoperative haemodynamic situation with increased insulin sensitivity.

Aortic Valve Stenosis↗
PubMed1982

Effect of valvular aortic stenosis on insulin sensitivity.

18 patients with valvular aortic stenosis were given an i.v. glucose tolerance test and an i.v. insulin tolerance test before and 4-36 months after valve replacement. Insulin and C-peptide response to the glucose challenge was smaller preoperatively whereas the glucose response was the same pre- and postoperatively. The effect on blood glucose of the i.v. insulin challenge was more pronounced preoperatively. It is concluded that insulin sensitivity was increased preoperatively and it is suggested that this was a metabolic adaptation to the haemodynamic situation in aortic stenosis, which may have implications for preoperative glucose-insulin-potassium treatment.

Aged↗
PubMed1981

Intrapleural instillation of streptokinase. Effects on systemic fibrinolysis.

Ten consecutive patients aged 25 to 75 with postoperative empyema or hemothorax conventionally treated with drainage without sufficient effect were given intrapleural instillations of streptokinase (Kabikinase, 250,000 IE) for 4 hours). The effects on systemic fibrinolysis were studied. Venous blood samples for determination of fibrinolytic activity on fibrin plates, plasminogen, alpha 2-antiplasmin, alpha 2-macroglobulin, fibrinogen, fibrin(ogen) degradation products (FDP) and thrombin time were taken before instillation, after instillation and then after 24 hours. Preinstillation values were compared to the values 4 and 24 hours after instillation with Student's paired t-test. There were no differences in fibrinolytic activity, alpha 2-macroglobulin and thrombin time. There was a slight increase in plasminogen, alpha 2-antiplasmin and fibrinogen, probably due to an acute phase reaction. Fibrin degradation products showed an increase with border line significance. These changes are not consistent with generalized fibrinolysis, and it is concluded that intrapleural instillations of streptokinase can be given safely in the early posttraumatic or postoperative period.

Adult↗
PubMed1980

Thermographic demonstration of uneven myocardial cooling in patients with coronary lesions.

Low temperature is an important factor in protecting the myocardium during an operation on the heart. This can be difficult to accomplish if the cold cardioplegic solution is hindered by occlusions or stenosis of the coronary arteries. We used thermography to study myocardial temperature during infusion of cold cardioplegic solution. Slow cooling was recorded distal to coronary stenosis or occlusions, thereby indicating insufficient protection of the myocarium in these areas.

Aortic Valve Stenosis↗
PubMed1980

The growth of human atherosclerotic and non-atherosclerotic aortic intima and media in vitro.

The capacity for and the pattern of growth in vitro of human aortic smooth muscle from normal intima and media and from plaque intima was studied. For media tissue outgrowth occurred but decreased with age and was virtually absent for media from patients more than 60 years of age. Intima did not show a similar age-related decrease which indicates a role of the intimal smooth muscle as a tissue reserve independent of age. Some of the intima outgrowths reverted spontaneously after 8-9 weeks suggesting a state of tissue senescence. The growth patterns of non-atherosclerotic tissue and atherosclerotic were grossly similar; the outgrowth from lipidrich atherosclerotic tissue contained, in addition, one large and one very small variety of "foam" cell.

Adult↗
PubMed1978

Physical training of patients with intermittent claudication: indications, methods, and results.

Supervised dynamic physical training for 4 to 6 months as a treatment of intermittent claudication was studied in 148 patients who had clearcut symptoms for more than 6 months. Nineteen patients could not complete the planned training program because of cardiac complications, rapid progress of the disease, intercurrent disease, or social reasons. Before the training was started, walking tolerance and calf blood flow were determined. The intensity of each training session (three times per week) was adjusted to the patient's cardiac tolerance as predicted by the cardiac tolerance test. The walking ability increased in 88% of the patients and the average increase was 234%, while the calf blood flow remained unchanged. After the training period, more than 40% of the patients could walk 1,000 m or more. The increase in walking ability was independent of the location of the atherosclerotic lesion or the presence of diabetes. It is concluded that physical training is a good alternative to reconstructive surgery in the treatment of patients with intermittent claudication. It does not interfere with the surgical possibility if operation becomes necessary in the immediate or later course of the disease.

Adult↗
PubMed1977

Vein patch grafting for repair of short ureteric strictures.

The generally accepted treatment for short and medium-length strictures of the ureter has been to split the stricture and splint the ureter for a month or more. A new method is here described in which the ureteric stricture is split and the opening is covered with a vein patch-graft. The length of hospital stay is considerably reduced by this operation. Four successfully treated cases with follow-up periods of six months to ten years are presented.

Adult↗