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Biomedical subjects

J Godtfredsen

Publications and source records attributed to J Godtfredsen.

At least 55 records · Page 3Linked to original sources
PubMed1988

Left ventricular volumes during graded upright exercise in healthy untrained subjects.

Left ventricular (LV) volume changes were studied by radionuclide cardiography at rest and during graded upright bicycle exercise in seven healthy untrained men aged 21-30 years. The exercise-induced changes in LV volumes were most pronounced during mild exercise: from rest to 25% submaximal exercise stroke volume increased by 26% and LV ejection fraction from 0.60 to 0.69 (both P less than 0.01), whereas further increments of the work load resulted in only small changes of these variables. LV end-diastolic volume increased initially by 10% (P less than 0.05) but returned to baseline values at higher work loads, whilst a rather constant decrease was recorded in LV end-systolic volume during increasing exercise loads. Changes in plasma catecholamine levels were most pronounced at the high work loads, indicating that these hormones are not directly contributing to the LV volume changes.

Adult↗
PubMed1988

The reliability of measuring left ventricular ejection fraction by radionuclide cardiography: evaluation by the method of variance components.

A statistical model based on the method of variance components was applied to obtain confidence statements for single and repeat determinations of left ventricular ejection fraction by radionuclide techniques. With this approach variance caused by individual factors in the measurement procedure is estimated to allow calculation of confidence intervals based on single measurements and the detection limits for changes. Six study groups made up of a total of 143 subjects were examined by both multigated equilibrium and first pass imaging. Under favourable conditions (with an updated gamma camera and experienced observer) the 95% confidence interval with a single measurement of left ventricular ejection fraction by equilibrium imaging was +/- 3 ejection fraction units, compared with +/- 6 units with the first pass technique (one ejection fraction unit = 1/100 of the possible values from 0.00 to 1.00). The minimal significant changes (at the 5% level) in measured equilibrium left ventricular ejection fraction at intervals of 15 min, 3 days, 1, 3, and 4 weeks were +/- 4, +/- 4, +/- 5, +/- 5, and +/- 6 units, respectively. The corresponding minimal detectable changes in a subject's "true" left ventricular ejection fraction for the same intervals were +/- 7, +/- 7, +/- 10, +/- 10, and +/- 12 units respectively. With first pass imaging, only average values for the variation at repeat determination could be calculated. The minimal significant change in measured first pass left ventricular ejection fraction was +/- 7 units, and the minimal detectable change in "true" left ventricular ejection fraction was +/- 14 units. Measurements of left ventricular ejection fraction by equilibrium technique were generally more reproducible than first pass determinations because the variability caused by study acquisition, observer analysis, and residual errors was smaller. The method of variance components appears to be well suited to the evaluation of quantitative biological measurements in clinical use. The popularity of established procedures may obscure the lack of basic information about method evaluation.

Adult↗
PubMed1988

Atrial fibrillation: natural history, complications, and management.

Atrial fibrillation is a clinically important arrhythmia that carries important prognostic and therapeutic implications. Hypertension, ischemic heart disease, and rheumatic valvular disease are the commonest causes of atrial fibrillation. The presence of chronic or paroxysmal atrial fibrillation places the patient at increased risk for embolic stroke and/or death. When atrial fibrillation develops, there is loss of the atrial transport factor ("atrial kick"), with consequent decrease of cardiac output. Stroke output declines by 20-30% in normal individuals with loss of atrial kick; the decline in stroke output is considerably larger in patients with heart disease. Atrial fibrillation can be electrically or pharmacologically reverted to sinus rhythm. Even patients with refractory atrial fibrillation can be reverted to sinus rhythm with amiodarone.

Anti-Arrhythmia Agents↗
PubMed1988

Central and peripheral haemodynamic changes after alcohol ingestion.

Central and peripheral haemodynamic changes 1 and 8 hours after alcohol ingestion were studied in seven healthy men, aged 21-30 years, by radionuclide cardiography and strain gauge plethysmography. Heart rate (HR) increased by 12% and cardiac output (CO) by 24% 1 hour after alcohol ingestion (mean serum ethanol 35 mmol/l). Left ventricular (LV) ejection fraction (EF) decreased by 5% because of endsystolic dilation and the forearm blood flow increased by 140%. Eight hours after alcohol ingestion (serum ethanol 21 mmol/l.) hangover symptoms were present in all subjects. HR and CO remained increased by 19% and 23%, respectively. A 4% increase was recorded in LVEF. The total peripheral resistance was reduced by 25%, while the forearm blood flow had returned to baseline values. No significant changes in plasma catecholamines were recorded. Apart from a slight increase in CO at 1 hour no haemodynamic changes were recorded after ingestion of an isovolumic, isocaloric drink. The present findings suggest that acute alcohol intoxication causes impairment of LV contractility, but that tachycardia results in an increase in cardiac output accompanied by an increased blood flow in the forearm. In the early hangover phase, when the serum ethanol is still elevated, cardiac output remains enhanced because of tachycardia, although the sympathetic nervous activity as measured by the plasma norepinephrine level is not influenced. A reduced total peripheral resistance may contribute to the increase in LV contractility in spite of sustained alcohol intoxication.

Adult↗
PubMed1988

Cardiac function after alcohol ingestion in patients with ischemic heart disease and cardiomyopathy: a controlled study.

Thirty male patients with ischemic heart disease and cardiomyopathy entered a controlled study of the acute effects of alcohol on cardiac function evaluated by right heart catheterization. Twenty patients, nine with angina pectoris and 11 with congestive heart failure, were studied during alcohol intoxication, and ten patients, five with angina pectoris and five with heart failure, served as a control group. The mean serum ethanol concentration in the alcohol group was 93 mg/100 ml (S.D. 17). The systemic arterial blood pressure was reduced by 6% in the alcohol group, P less than 0.05 compared with the control group. No significant changes occurred in the central venous pressure, the pulmonary artery pressure, the pulmonary capillary wedge pressure, or in cardiac output, stroke volume and total peripheral resistance. Alcohol intake in moderate doses has no measurable effect on pulmonary blood pressures or cardiac output in patients with ischemic heart disease and cardiomyopathy. Such an effect may, however, be masked by a reduction of afterload.

Aged↗
PubMed1987

Left ventricular function during alcohol intoxication and autonomic nervous blockade.

Eight healthy young subjects (6 men, 2 women) entered a controlled investigation of left ventricular (LV) function during alcohol intoxication and autonomic nervous blockade. Radionuclide cardiography was performed at rest and during upright 50% submaximal bicycle exercise. During alcohol intoxication alone (serum ethanol 30 mmol/liter), heart rate at rest increased by 11% (p less than 0.05) and LV ejection fraction (EF) decreased by 6% because of end-systolic dilation. No significant alcohol-induced hemodynamic changes were observed during exercise. Plasma norepinephrine concentration increased by 29% (p less than 0.05), whereas plasma epinephrine concentration did not change. During subsequent autonomic nervous blockade with intravenous metoprolol and atropine infusion, heart rate at rest further increased and systolic blood pressure decreased. These changes were not, however, significantly different from those of a control experiment in which a nonalcoholic isocaloric drink was substituted for alcohol. Plasma norepinephrine levels at rest and during exercise were 25% and 32% higher (both p less than 0.05), respectively, than those during control conditions. Plasma epinephrine concentrations did not change. These findings suggest that alcohol intoxication has a depressant effect on LV function at rest that stimulates autonomic nervous blockade. The increased sympathetic nervous activity during exercise appears to be a toxic rather than a compensatory effect of alcohol.

Adult↗
PubMed1987

Haemodynamic response to exercise in patients with alcoholic liver cirrhosis.

Physical work capacity was evaluated by a multistage bicycle exercise test in 29 patients, 22 men and seven women aged 35-61 years (mean 49) with alcoholic liver cirrhosis and in a sex- and age-matched control group. The maximal work load was reduced in the patient group, mean 122 vs. 186 watts in men (P less than 0.001), and 60 vs. 119 watts in women (P less than 0.005). Resting heart rate was higher in patients (91 vs. 78 beats X min-1, P less than 0.005), and the maximal heart rate was lower (159 vs. 170 beats X min-1, P less than 0.001) compared with controls. Thirteen of 29 (45%) patients compared with 5 of 29 (17%) control subjects had an increase in left ventricular ejection fraction of less than or equal to 5% during exercise (P less than 0.05). The present results suggest that an impaired capacity of the cardiac function to respond adequately to physical stress may at times contribute to the reduced physical work capacity seen in patients with alcoholic liver cirrhosis.

Adult↗
PubMed1987

Left ventricular performance in alcoholic patients without chronic liver disease.

Left ventricular performance was studied non-invasively in 24 chronic alcoholics without liver disease. Twelve patients who had abstained from drinking for at least one month (group A) and 12 sex and age matched patients who had ceased drinking during the preceding 24 hours (group B) were studied at rest and during 50% submaximal exercise. Cardiac output and stroke volume were measured by first passage and left ventricular ejection fraction by multigated radionuclide cardiography. Twelve healthy sex and age matched controls were also studied. Haemodynamic variables were similar in group A and the controls, except that in group A left ventricular end systolic volume index did not decrease during exercise. In group B the heart rate was increased both at rest and during exercise and plasma noradrenaline concentrations were increased. The stroke volume index did not increase significantly during exercise in group B. In addition, the increase in left ventricular ejection fraction was smaller in group B than in controls. End systolic contraction was reduced in group B patients and diastolic blood pressure was increased. These results suggest that cardiac abnormalities in chronic alcoholics may be reversed after cessation of drinking if no chronic liver disease is present. Recent alcohol consumption increases sympathetic nervous activity, impairs cardiac contractility, and increases afterload during physical stress.

Adult↗
PubMed1987

Effects of autonomic blockade on cardiac function at rest and during upright exercise in humans.

The cardiac function was studied by radionuclide cardiography in eight healthy subjects at rest and during submaximal upright exercise before and after autonomic blockade with metoprolol and atropine. At rest the median stroke volume was reduced by 21% during autonomic blockade (P less than 0.01), but cardiac output was maintained by a concomitant increase in heart rate. The systolic blood pressure was reduced from 120 to 105 mmHg (P less than 0.01), and left ventricular ejection fraction was reduced from 61 to 56% (P less than 0.05). After autonomic blockade the heart rate reached during exercise was the same. Stroke volume and cardiac output were maintained through cardiac dilation. The increase in left ventricular end-diastolic volume was 31 vs. 10% during control conditions (P less than 0.01). The systolic blood pressure was reduced from 174 to 135 mmHg (P less than 0.01). Left ventricular ejection fraction was reduced from 75 to 67% (P less than 0.05), but the increase from rest to exercise was preserved. Total peripheral resistance was reduced by 17% (P less than 0.05). These findings suggest that the heart possesses intrinsic mechanisms to maintain cardiac output during submaximal upright exercise. End-diastolic dilation results in a preserved stroke volume despite a reduced contractility.

Adult↗
PubMed1987

Autonomic nervous control of postprandial hemodynamic changes at rest and upright exercise.

Postprandial hemodynamic changes were studied in healthy subjects at rest and during exercise in the upright position with and without autonomic blockade of the heart. At rest cardiac output increased 61% mostly because of a stroke volume increase accomplished by left ventricular end-diastolic dilation. These changes seemed to be dependent on the autonomic nervous system, whereas the postprandial heart rate increase did not. During exercise cardiac output was 23% higher after food intake due to a rise in both stroke volume and heart rate. These changes were apparently under influence of the autonomic nervous system, whereas left ventricular dilation was not. The present findings indicate that most of the postprandial changes in the central circulation are under control of the autonomic nervous system.

Adult↗
PubMed1987

First-pass radionuclide determination of cardiac output: an improved gamma camera method.

A technique for noninvasive determination of cardiac output by aid of first-pass radionuclide cardiography is described. After intravenous injection of 10-15 mCi technetium-99m-(99mTc) labeled red blood cells the method requires acquisition of a first passage time-activity curve recorded with a gamma camera over the left ventricle, the background corrected left ventricular count rate recorded after complete mixing of the tracer in the circulation, and determination of the distribution volume of the tracer. The method was applied in 14 patients with heart disease of various origins and evaluated against the conventional tracer dilution technique with arterial sampling of blood activity. Cardiac output determinations by external counting ranged from 2.30 to 8.56 l/min, mean +/- s.d. 4.50 +/- 1.66 l/min and by arterial blood sampling from 1.88 to 8.96 l/min, mean +/- s.d. 4.52 +/- 1.71 l/min. An excellent correlation was demonstrated between the two techniques, r = 0.978 (p less than 0.001). When no background subtraction was applied to the left ventricular counts at equilibrium, radionuclide cardiac output values were approximately 40% higher than those obtained by arterial sampling. The new first-pass radionuclide cardiographic technique may prove a useful tool in the noninvasive evaluation of cardiac function, especially in patients with arrhythmias and/or valvular incompetence.

Adult↗
PubMed1987

Determination of cardiac output by first passage radiocardiography: theoretical considerations and phantom studies.

Non-invasive determination of cardiac output by aid of precordial first passage radiocardiography may prove a useful tool in the management of cardiac disorders. The basic concepts of a method together with theoretical assumptions necessary for the clinical application of the method are described. The principle of the technique was tested in a cardiac phantom model with adjustable stroke volume and heart rate, in which background problems were avoided. First passage radiocardiography gave highly accurate cardiac output determinations compared with the 'true' phantom values, r = 0.998 (p less than 0.001).

Cardiac Output↗
PubMed1987

Planar stress thallium-201 scintigraphy. First experiences with a new circumferential programme.

A new computer programme was used in 22 patients referred for suspected ischaemic heart disease (IHD) or for assessment of the size of a suspected ischaemic or infarcted area. An interpolative method was used to construct the net myocardial images. Initial imaging in three projections was started at five minutes after thallium-201 injection and delayed imaging three hours after the injection. The data were presented as analog images, circumferential profile curves, and washout curves. The calculated delayed/initial count ratio is an important measure of redistribution. In the 12 patients referred to detect clinically or electrocardiographically suspected IHD, the diagnosis IHD was made by the cardiologists on the basis of current routine criteria and the thallium test. The technique was found useful in localising and assessing the size of a suspected ischaemic or infarcted area in nine of 10 patients. Our experience with the new programme confirms the experience of others that a combination of analog images and computer processed data gives much more precise information than the visual inspection of the analog pictures alone.

Adult↗