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Biomedical subjects

S Simonsen

Publications and source records attributed to S Simonsen.

At least 127 records · Page 7Linked to original sources
PubMed1984

Haemodynamic effects of ICI 118,587 in cardiomyopathy.

The haemodynamic effects of a new beta 1-adrenoceptor partial agonist, ICI 118,587, were studied in 10 patients with dilated cardiomyopathy and moderate to severe cardiac failure. Simultaneous right and left heart catheterisations were performed. Resting central haemodynamic indices were measured before and 15 min after an intravenous dose of 0.05 mg/kg and then 15 min after an additional intravenous dose of 0.15 mg/kg of ICI 118,587. Left ventricular performance was improved--as shown by significant increases in systolic left ventricular pressure, maximum rate of rise in left ventricular pressure (dP/dt max), and cardiac output and a decrease in left ventricular end diastolic pressure--without an undesirable increase in heart rate. The top of the dose response curve was reached after the lower dose. An important unwanted effect was seen in the most severely diseased patient, whose left ventricular systolic pressure, dP/dt max, and cardiac output decreased. This was probably due to the drug's antagonistic property supervening in this patient, who probably had high concentrations of circulating catecholamines. It is concluded that ICI 118,587 has a positive inotropic action and improves cardiac performance in patients with dilated cardiomyopathy and moderate cardiac failure, although care should be exercised when the drug is given intravenously in severe failure.

Adrenergic beta-Agonists↗
PubMed1984

Effect of adrenaline on myocardial oxygen consumption during selective and non-selective beta-adrenoceptor blockade comparison of atenolol and pindolol.

The effect of adrenaline on myocardial oxygen consumption (MVO2) during selective and non-selective beta-adrenoceptor blockade was examined in 26 patients with angina pectoris. Cardiac venous flow was measured by thermodilution and blood was sampled for metabolic studies. Thirteen patients were given atenolol 62.5 micrograms/kg i.v. and the other 13 patients pindolol 7.5 micrograms/kg i.v. Measurements were repeated before and during infusion of adrenaline 0.1 microgram/kg/min. Compared to the control situation, adrenaline increased MVO2 more in atenolol-treated (39%) than in pindolol-treated patients (11%). This was partly due to augmented external cardiac work. Arterial FFA was considerably increased in the atenolol group (105%), but was unchanged in the pindolol group, suggesting an additional metabolic mechanism. Thus, adrenaline stimulation, which is comparable to that found in acute myocardial infarction, increases MVO2 more during selective than non-selective beta-blockade.

Adult↗
PubMed1983

Haemodynamic and metabolic effects of timolol (Blocadren) on ischaemic myocardium.

The effects of timolol (2.5 mg i.v.) on coronary haemodynamics and myocardial metabolism were studied in 26 patients with angina pectoris. Cardiac venous flow (CVF) was measured by thermodilution technique. Blood was sampled for metabolic studies. Angina pectoris was induced by atrial pacing and the same heart rate was regained after timolol. Metabolic ischaemia was defined as reduction in myocardial lactate extraction ratio (MLE) by at least 50% and to a ratio below 0.15. The study was completed in 22 patients, 9 of whom fulfilled the metabolic criteria for ischaemia. This subgroup did not differ from the total group in any other respect than in lactate metabolism. Beta-adrenergic blockade reduced myocardial oxygen consumption (MVO2) and CVF significantly at rest, but MVO2, CVF, myocardial glucose uptake and MLE were unchanged during pacing despite a decrease in systolic aortic pressure, ejection time and reduced myocardial free fatty acid uptake. Conclusively, timolol did not reduce MVO2 and metabolic ischaemia during pacing-induced angina.

Angina Pectoris↗
PubMed1983

The influence of open-heart surgery during extreme hemodilution on the hemostatic mechanism in the dog.

12 Labrador retriever dogs had mitral disc valves implanted during cardiopulmonary bypass (CPB) with extreme hemodilution, obtained with preoperative blood withdrawal, the use of blood-free priming fluid during perfusion, and retransfusion of autologous blood. Before operation, platelet adhesiveness as well as the reactivity of the intrinsic and extrinsic coagulation systems were markedly higher than in man. During CPB, the number of functioning platelets was very low, but increased after retransfusion, and were after 4 h twice as high as in 7 human patients who received aortic disc valves during CPB with extreme dilution. The extrinsic coagulation system also reacted much faster during and after CPB in the dogs, and heparin activity was rapidly neutralized and intrinsic coagulation normalized in them. Intravascular coagulation did not occur, and more hemolysis was induced in the dogs than in the patients. 3 of the dogs died from valve thrombosis within 24 h. The high reactivity of platelets and coagulation systems in the dog makes the canine model a very difficult one for experimental open-heart surgery because of a strong tendency to thrombosis.

Animals↗
PubMed1983

Reproducibility of ischaemic lactate metabolism during atrial pacing in man.

The reproducibility of myocardial ischaemia provoked by atrial pacing was studied in two groups of patients. The heart rate was slowly increased (10 beats per fourth min) until angina in group A, and quickly increased (10 beats per 20 s) in group B. Cardiac venous flow was measured by thermodilution and blood was sampled for metabolic studies at rest and during the maximum obtained heart rate and repeated after 20 min of rest. Ischaemia was defined as a reduction in myocardial lactate extraction ratio by 50% and to a ratio lower than 0.15. Lactate metabolism changed from production (-0.06 +/- 0.05) during the first pacing to extraction (0.05 +/- 0.05) during the second in group A (p less than 0.02). Lactate metabolism was quite reproducible in group B. All the other metabolic and haemodynamic parameters were unchanged in both groups. We conclude that the duration of atrial pacing is important for the reproducibility of pacing-induced myocardial ischaemia.

Cardiac Pacing, Artificial↗
PubMed1983

Tolerability and usefulness of iohexol in cardioangiography. II. A double blind comparison with metrizoate.

The new non-ionic contrast medium iohexol (Omnipaque) was compared with the ionic medium sodium meglumine calcium metrizoate (Isopaque Coronar) in a double blind, two-group trial. Iohexol resulted in significantly fewer and smaller subjective reactions than metrizoate. Changes of left ventricular and aortic pressure were statistically significantly less after injection of iohexol than of metrizoate. ECG recordings did not significantly differ in the two groups. Analysis of biochemical parameters showed no statistical differences between the two groups. Determination of serum enzyme activities revealed no signs of myocardial injury, and no impairment of glomerular filtration rate was detected by radionuclear renal function test. Similar radiographic quality was obtained with both media.

Adult↗
PubMed1983

Myocardial lactate metabolism during pacing induced angina pectoris.

Myocardial lactate metabolism was studied in 20 patients with coronary heart disease during and immediately after slight angina pectoris induced by atrial pacing. Myocardial lactate extraction ratio (MLE) decreased from 0.27 +/- 0.03 (SEM) before angina to 0.01 +/- 0.06 during angina, and further to -0.32 +/- 0.11 at 15 sec after pacing. Lactate production was found to occur in eight patients during pacing and 13 patients after pacing. Cardiac venous flow was measured by thermodilution in eight of these patients. 'Net ischaemic lactate efflux' increased by 23 +/- 4 mumol/min 15 sec after pacing, whereas 'lactate uptake in non-ischaemic regions' diminished by 11 +/- 2 mumol/min. Lactate production 15 min after pacing was revealed in all patients with subtotal stenosis of the left anterior descending coronary artery (LAD), whereas it was less frequently observed in patients with occluded LAD and collaterals to the post-stenotic area. Increased washout of metabolites from the ischaemic myocardium during the early recovery period is the main reason for the rather high sensitivity of ischaemia detection by this procedure. This permits shorter pacing periods and less pain than in earlier studies. Both MLE and electrocardiographic changes were equally reproducible after 20 and 45 min recovery period.

Angina Pectoris↗
PubMed1982

Anterior left ventricular wall circulation in patients with coronary artery disease.

The human anterior left ventricular circulation was investigated at rest and during submaximal atrial pacing by measuring the great cardiac venous blood flow by the constant infusion thermodilution method. Forty-seven patients with angina pectoris participated in the study and were grouped stepwise according to degree of arteriosclerosis in the left anterior descending coronary artery (LAD), from normal to occluded vessel. Special attention was paid to patients with earlier infarcts and to collateral circulation. Blood flow to the myocardium was slightly but significantly reduced only among patients with a subtotal stenosis of the LAD without demonstrable collateral circulation, and only during atrial pacing. This conforms with an increased coronary arteriolar resistance in these patients. Myocardial oxygen extraction was, however, increased in all groups of patients with LAD stenosis from 50% to occlusion, except in patients with an earlier anterior wall myocardial infarction. This suggests a disproportion between oxygen demand and blood flow leading to increased extraction in patients without infarcts and a shunting of blood through scarred myocardium with a low oxygen demand in those with a previous necrosis, and is confirmed by a decreased ratio between myocardial flow and cardiac work. Patients with an increased oxygen extraction may benefit from coronary bypass surgery to the LAD area while those without may not.

Angina Pectoris↗
PubMed1982

Pacing induced angina and platelet reactivity.

Platelet function was studied during pacing-induced angina pectoris in nine patients with coronary heart disease. Blood was sampled via catheters from the coronary sinus and the aorta at rest and during angina. The influence of the sampling procedures on the platelet function was evaluated in blood collected via catheters and via short venflons. The catheter induced pseudopod formation in the platelets. The aggregation response was similar, while platelet retention as measured with Hellem's method for native blood, was slightly lower in blood collected via catheters than via venflons. At rest the maximal rate of primary, ADP-induced aggregation was lower in blood from the coronary sinus than from the aorta, as was the percentage of platelets retained in glass bead columns. The ability of platelets to produce prostaglandin metabolites, estimated from malondialdehyde formation after thrombin stimulation was also moderately, but significantly lower in coronary sinus blood. During pacing-induced angina primary, ADP-induced aggregation and platelet retention values remained significantly lower in blood that had passed the coronary circulation than the aortic blood. There were no differences between aortic or coronary sinus samples collected at rest than during pacing. Unchanged platelet counts indicates that trapping of platelets did not occur. Thus, platelet reactivity was lower in coronary sinus than aortic blood at rest in patients with coronary heart disease, and a moderate pacing-induced angina did not influence this pattern.

Adenosine Diphosphate↗
PubMed1981

Pharmacokinetics of disopyramide in patients with imminent to moderate cardiac failure.

The parmacokinetics of disopyramide (DP) in 10 patients with imminent to moderate cardiac failure has been studied and compared with the results in normal volunteers. The biological half life of rapid distribution (T1/2 alpha) and of elimination (T1/2 beta) were increased (11.1 +/- 4.4 min and 9.7 +/- 4.2 h, respectively). Total body clearance (Clt) was decreased (0.467 +/- 0.215 ml . min-1 . kg-1), and the volume of distribution (Vd) was slightly reduced (0.610 +/- 0.1361 . kg-1), probably due to the lower cardiac index. After oral administration, the time of peak serum concentration was increased (139 +/- 89 min), and the mean peak serum concentration (2.4 +/- 0.8% dose . 1-1) was also higher than reported in normal subjects. Comparison of the areas under the concentration versus time curves after intravenous and oral administration (AUC i. v. and AUC oral) showed that DP was almost completely absorbed, its bioavailability being 97.5 +/- 15.0%.

Administration, Oral↗
PubMed1981

Strut fracture in the new Bjørk-Shiley mitral valve prosthesis.

The case of a patient with the new type Bjørk-Shiley aortic and mitral valve prosthesis is described. Three months after implant she suffered acute heart failure and died. Post-mortem examination revealed a fractured outlet strut in the mitral valve prosthesis with dislocation of the disc. The fracture was regarded as due to excessive brittleness caused by demonstrated deposition of chromium-tungsten-carbide.

Aged↗
PubMed1981

Haemodynamic changes with the administration of nitrous oxide during coronary artery surgery.

Haemodynamic responses to 50% nitrous oxide in oxygen during coronary artery surgery were investigated in 10 patients. Morphine, diazepam and pancuronium were given intravenously as both induction and maintenance anaesthesia. A significant decrease was seen in heart rate, arterial pressure, pulmonary artery pressure, heart rate-systolic arterial pressure product, peripheral vascular resistance, left ventricular end-diastolic pressure, dP/dT of the left ventricle and resistance as measured in the graft to the left anterior descending coronary artery (LAD). No variations occurred in cardiac output, stroke volume, flow in the LAD-graft, pulmonary artery pressure or heart rate-systolic pulmonary artery pressure product or in dP/dT of the right ventricle. Pulmonary vascular resistance increased. It was concluded that left ventricular performance did not decrease and that no deterioration of the oxygenation to the myocardium seemed to occur.

Adult↗
PubMed1981

Determination of pressure gradient in the Hancock mitral valve from noninvasive ultrasound Doppler data.

The accuracy with which the pressure gradient in the Hancock mitral valve can be determined from noninvasive ultrasound Doppler data was explored in a study of eight adult patients. The mean manometric pressure gradient (delta PM) was determined by performing simultaneous left atrial and left ventricular catheterization. The mean diastolic pressure gradient was also determined from noninvasive ultrasound data (delta PU). Identical cardiac cycles were used to compare delta PM and delta PU. In the eight patients delta PM ranged from 3.0 to 9.0 mmHg and cardiac output from 3.7 to 5.5 l/min. The difference delta PM-delta PU was 0.3 +/- 0.9 mmHg (mean +/- SD). The results thus indicated that noninvasive ultrasound can determine the mean diastolic gradient in the Hancock mitral valve with an accuracy which approaches that attained with conventional manometric methods.

Blood Pressure↗