Search PubMed⌕ Search

Biomedical subjects

H Kelbaek

Publications and source records attributed to H Kelbaek.

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

Metoprolol abolishes exercise-induced left ventricular dysfunction in patients with silent ischemia.

Left ventricular systolic function is reduced during episodes of silent ischemia in patients with coronary artery disease (CAD). Left ventricular ejection fraction (LVEF) is increased at least 5 absolute percent during exercise in most normal subjects; however, in patients with CAD, LVEF often remains unchanged or decreases. The anti-ischemic effect of beta-adrenergic receptor blockade is well documented, including a reduction of exercise-induced electrocardiographic ST depressions; however, the effect of these drugs on left ventricular volume changes during exercise in patients with silent ischemia is unknown. The aim of this study was to evaluate the effect of a cardio-selective beta-blocking agent, metoprolol, on rest and exercise LVEF in patients with silent ischemia, using radionuclide cardiography. Fifteen patients with silent ischemia completed a double-blind, placebo-controlled crossover study at rest and during submaximal exercise. LVEF remained unchanged during exercise in the placebo phase (56% to 58%; p = NS), but even though LVEF tended to decrease 56% during rest after metoprolol versus 52% after placebo (p = NS), the LVEF increase from rest to exercise resembled a normal LVEF response, 52% to 58% (p = 0.005). Exercise-induced electrocardiographic ST depressions were also reduced during metoprolol treatment. In patients with silent ischemia, the exercise-induced change in LVEF rises significantly during metoprolol treatment. The mechanism may be a reduction in myocardial ischemia as indicated by a reduction in ischemic electrocardiographic findings.

Adrenergic beta-Antagonists↗
PubMed1996

Haemodynamic effects of eating: the role of meal composition.

1. The purpose of this study was to investigate the effect of fractional meal stimulation on postprandial haemodynamic changes, the possible correlation between these changes and the potential mediating role of circulating catecholamines and insulin. 2. Healthy young subjects were studied before and after ingestion of isocaloric, isovolumetric high-protein, carbohydrate or fat meals (80-85% of total energy), 60 kJ per kg of body weight. Multigated radionuclide cardiography with autologous 99mTc-labelled erythrocytes was performed for assessment of cardiac output, venous occlusion plethysmography to obtain forearm blood flow and Doppler-ultrasonography for portal vein flow. Plasma levels of catecholamines and insulin were determined by radioimmunoassay. 3. Cardiac output increased considerably after each meal, including the control meal (water) with only minor differences in extent and timing. Left ventricular volumes increased after food intake, most pronounced after carbohydrate and protein. Forearm blood flow increased only after carbohydrate and protein. Portal vein flow increased after all meals, especially after fat, but also after the control meal. There was a significant correlation between the increment in cardiac output and changes in forearm and portal vein flow, but no correlation between either haemodynamic response and plasma catecholamines or insulin. 4. Postprandial cardiovascular changes are not substantially different after various isocaloric and isovolumic meal compositions. Gastric distension seems to play a role in the increase in cardiac output, accomplished by ventricular dilatation. These changes seem to some extent to be linked to changes in muscle and splanchnic flow.

Adult↗
PubMed1996

Pre- and afterload reduction in chronic mitral regurgitation: a double-blind randomized placebo-controlled trial of the acute and 2 weeks' effect of nifedipine or isosorbide dinitrate treatment on left ventricular function and the severity of mitral regurgitation.

1. The acute effect and effect of 14 days' treatment with isosorbide dinitrate (ISDN) and nifedipine (NIF) was evaluated by radionuclide cardiography in patients with chronic mitral regurgitation and sinus rhythm. 2. In 23 patients with clinically stable disease blood pressure was lowered by 15% and left ventricular volume was reduced by 16-20% after 20 mg sublingual ISDN causing combined pre- and afterload reduction. Afterload reduction alone induced by 10 mg NIF resulted in an acute 9% decrease in left ventricular endsystolic volume, whereas forward stroke volume increased by 30%, and regurgitation fraction tended to decrease. No haemodynamic effects could be detected after 14 days' treatment with 20 mg ISDN orally twice daily (preload reduction), whereas 20 mg NIF twice daily (afterload reduction) caused an increase in forward stroke volume (18%) and a decrease in both regurgitant volume (20%) and regurgitation fraction (22%) without affecting blood pressure or heart rate. 3. ISDN and NIF have beneficial acute haemodynamic effects in patients with chronic mitral regurgitation probably due to their pre- and afterload reducing properties. The reduction in regurgitation induced by NIF appears to be sustained after 14 days therapy.

Administration, Oral↗
PubMed1996

Influence of meal composition on postprandial peripheral plasma concentrations of vasoactive peptides in man.

In a randomized cross-over study healthy non-obese male human subjects received standardized isocaloric, isovolumetric meals consisting of either carbohydrate, protein or fat and a non-caloric control meal consisting of an equal volume of water. Peripheral venous plasma concentrations of calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP), and peptide YY (PYY) were measured pre- and postprandially. Plasma CGRP concentrations were lowered following the protein meal and following the fat meal, but remained unaltered after carbohydrate or water ingestion. Plasma VIP concentrations increased slightly following the carbohydrate meal and following water loading. The PYY concentrations increased after the protein and the carbohydrate meal and a slight rise was observed following fat ingestion. Water loading did not affect the plasma level of PYY. We conclude that the postprandial peripheral plasma concentrations of CGRP, VIP and PYY are dependent on the caloric meal composition. The VIP, but not the CGRP and PYY concentrations seem to be influenced by gastric distension. The physiological significance of the postprandial alterations in peripheral concentrations of these peptides is at present uncertain.

Adult↗
PubMed1995

Dobutamine-atropine stress echocardiography in asymptomatic healthy individuals. The relativity of stress-induced hyperkinesia.

BACKGROUND: Interpretation of dobutamine-atropine stress echocardiography (DASE) is based on the assumption that the normal response to dobutamine-atropine infusion is characterized by increased systolic thickening and motion of the left ventricular (LV) walls, whereas a reduction or no change is considered indicative of coronary artery disease. The aim of this study was to quantitatively assess changes in LV dimension and wall motion patterns during DASE in a healthy population. METHODS AND RESULTS: Forty-two asymptomatic voluntary subjects (22 men) with a mean age of 59 years (range, 31 to 79 years) and a likelihood of < 5% for coronary artery disease underwent DASE with digital recording of two-dimensional and M-mode echocardiography at baseline and low-dose and peak infusion rates. Mean end-diastolic and end-systolic LV diameters and areas decreased and wall thicknesses increased progressively throughout the test. Wall motion and thickening increased from baseline to low-dose infusion in nearly all subjects. However, from low-dose to peak infusion, the mean absolute wall motion and relative wall thickening decreased by 13.1% (95% CI, 2.7 to 23.5) and 21.4% (95% CI, 6.4 to 36.4) regardless of age, sex, or use of atropine. Changes in fractional shortening and absolute wall thickening varied considerably, with a decrease observed in 15 and 13 individuals (36% and 31%), respectively. CONCLUSIONS: In healthy subjects, measures of wall motion and wall thickening increased from baseline to low-dose infusion but decreased from low-dose to peak infusion. These findings call for revision of the assumptions on which the common analysis of DASE is based.

Age Factors↗
PubMed1994

Mitral regurgitation determined by radionuclide cardiography: dependence on posture and exercise.

OBJECTIVES: To evaluate dependence of posture and exercise on the degree of mitral regurgitation using combined first pass and equilibrium radionuclide cardiography. DESIGN: 24 patients with clinically stable chronic mitral regurgitation and sinus rhythm were studied by first pass list mode and simultaneous multigated frame mode equilibrium radionuclide cardiography using red cells labelled with technetium-99m. RESULTS: When patients changed posture from supine to sitting upright, left ventricular volumes decreased considerably. Regurgitation tended to increase in patients with valve prolapse but decreased in patients with ischaemic heart disease and dilated cardiomyopathy. During submaximal bicycle exercise cardiac output increased without dilatation of the left ventricle. The increase in left ventricular forward stroke volume was more pronounced than that in the total stroke volume, leading to a considerable decrease in the regurgitant flow through the mitral valve. The repeatability and observer variability of radionuclide determination of regurgitation was acceptable, with limits of agreement within about 10%. CONCLUSIONS: Change in posture induces a normal haemodynamic response in most patients with chronic mitral regurgitation; the effect of posture on regurgitation depends on the underlying disease. Mild to moderate exercise causes no deterioration in the severity of regurgitation.

Adult↗
PubMed1994

Myocardial blood flow rate and capillary permeability for 99mTc-DTPA in patients with angiographically normal coronary arteries. Evaluation of the single-injection, residue detection method with intracoronary indicator bolus injection and the use of a mobile gamma camera.

The aims of the present study were to quantitate myocardial perfusion and capillary permeability in the human heart by means of the single-injection, residue detection method using a mobile gamma camera. With this method, the intravascular mean transit time and the capillary extraction fraction (E) can be determined in one experiment and in the same myocardial region. Eighteen patients with a history of chest pain episodes and angiographically normal coronary arteries were studied after intracoronary bolus injections of 99mTc-DTPA during elective coronary angiography. Two measurements were performed at a 15-min interval during resting conditions, and a third measurement was made during atrial pacing. Regions of interest were drawn in the left anterior descending (LAD) and the circumflex (CX) coronary artery perfusion beds. Sources of variation in plasma flow rate (fpl), E, and the calculated capillary permeability area product (PS) were determined. Spontaneous 15 min variations (mean of two values) for the LAD and the CX territory, respectively, gave a mean fpl(LAD) of 74.2 (measurement 1) and 77.8 ml.(100 g.min)-1 (measurement 2) (SD of the difference 7.5 ml.(100 g.min)-1) and fpl(CX) of 82.7 and 92.1 ml. (100 g.min)-1, respectively (SD of the difference 16.1 ml.(100 g.min)-1), and E(LAD) was 51.0 and 55.7%, respectively (SD of the difference 8.4%), and E(CX) was 52.9 and 50.4%, respectively (SD of the difference 5.9%). During atrial pacing, the rate-pressure product increased by 97%, and in the LAD area fpl increased by 46% (p < 0.05), E decreased by 6% (NS), and PS increased by 39% (NS), whereas in the CX region flow increased by only 9% (p < 0.01), E decreased by 15% (p < 0.05), and PS decreased by 15% (NS) compared with baseline values. Both the spontaneous variation and the observer variation are low. The reduced vasodilator response in the CX region in combination with the decrease in E, which reduce the supply of nutrients, may play a role in the symptoms of these patients.

Adult↗
PubMed1993

Angiotensin converting enzyme inhibition at rest and during exercise in congestive heart failure.

The haemodynamic effects of the sulfhydryl-containing angiotensin converting enzyme inhibitor, zofenopril, were studied in patients in New York Heart Association functional class II and III. Twenty-one clinically stable patients with coronary artery disease or cardiomyopathy completed a randomized double-blind treatment period of 2 months with either 15 mg zofenopril once daily or placebo. Regular therapy with digoxin and diuretic drugs was continued. Left ventricular volumes were measured by radionuclide angiography at rest and during submaximal bicycle exercise. Zofenopril significantly increased mean stroke volume at rest from 59 to 67 ml (48 vs 48 ml in the control group, 95% confidence interval of the difference 1 to 16 ml) and left ventricular ejection fraction at rest from 39 to 43% (30 vs 30% in the control group, 95% confidence interval of the difference 1 to 8%). No significant changes occurred in heart rate, cardiac output, and blood pressure at rest, and zofenopril did not result in haemodynamic alterations during exercise. Thus, 15 mg of the sulfhydryl-containing angiotensin converting enzyme inhibitor, zofenopril, administered once daily to patients with moderate heart failure increases left ventricular function at rest, but not during exercise.

Adult↗
PubMed1993

Venous plasma noradrenaline increases with age: correlation to total blood volume and long-term smoking habits.

Venous plasma noradrenaline (NA), cardiac index, total blood volume, and other haemodynamic parameters were measured in 12 young (median age of 29, range 21-37 years) and 10 elderly (median age of 68, range 55-85 years) healthy male subjects in the resting supine and sitting positions. Cardiac index was equal in the two groups and did not correlate to plasma NA. Plasma NA was significantly elevated in the elderly subjects in the sitting position (2.47 +/- 0.28 vs. 1.80 +/- 0.13 nmol l-1, P = 0.038). Elevated plasma NA levels were confined to elderly long-term smokers. Sitting plasma NA was significantly correlated to total blood volume corrected for body weight, r = -0.720, P = 0.0002, but with no difference in blood volume between smokers and non-smokers. It is concluded, that long-term smoking may result in elevated plasma NA levels seen in elderly subjects. It is suggested, that this is a compensatory mechanism to vascular dilation induced by chronic smoking.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

Comparison between reference values for 201thallium uptake and washout from the myocardium after exercise and after dipyridamole.

A slow washout of 201Thallium has a high diagnostic and prognostic value for coronary artery disease. The aim of the present work was to contribute with reference data on 201Tl uptake and washout from the myocardium. With a quantitative method using circumferential profiles and interpolative background subtraction we performed 201Tl myocardial imaging in two groups of subjects with a low probability of coronary artery disease. Washout in per cent is defined as (1-D/I).100, where D is the delayed uptake rate and I the initial uptake rate. In group A (n = 16) myocardial hyperaemia was induced by maximal exercise, in group B (n = 15) by intravenous infusion of dipyridamole. In group A, the mean washout was 52%, and in group B it was 34% (P < 0.001). The delayed uptake rate D was significantly higher after dipyridamole, 58.4 cps, than after exercise, 44.5 cps (P < 0.05). There was no significant differences in I between the two groups. The findings regarding D and I explain that the washout is slower after dipyridamole than after exercise, as the mean D/I ratio was 0.48 in group A and 0.66 in group B (P < 0.001).

Adult↗
PubMed1993

Observer variability of radionuclide left ventricular volume determination at rest and during exercise.

The reproducibility expressed as the intra- and interobserver variation in the determination of cardiac left ventricular (LV) volumes by the radionuclide multigated equilibrium technique in the upright position is presented. No systematic difference was found in the reproducibility between LV volumes determined in healthy subjects and cardiac patients or between examinations performed at rest and during exercise. The intra- and interobserver variation were of the same magnitude. SD of the difference was 8 to 9 ml for LV end-diastolic volume, 4 to 7 ml for LV end-systolic volume, and 2 to 5% for LV ejection fraction. Thus, there is a 95% probability that repeat measurements, either by the same observer or by 2 independent observers, will result in the same LV end-diastolic volume within 18 ml, LV end-systolic volume within 11 ml, and LV ejection fraction within 8%. Only 15% of the variation can be ascribed to determination of the attenuation correction factor.

Adult↗
PubMed1992

Reliability of first-pass radionuclide determination of cardiac output in the upright position at rest and during exercise.

The reliability of non-invasive determination of cardiac output using first-pass radionuclide cardiography at rest and during exercise in the upright position was evaluated in 20 patients with coronary artery disease. Cardiac output values ranged from 2.97 to 5.99 l/min at rest and from 5.08 to 10.82 l/min during exercise. Cardiac output results obtained by the radionuclide method were compared with those derived from the thermodilution technique performed simultaneously. The mean difference between the two techniques was 0.02 l/min at rest and -0.34 l/min during exercise; the limits of agreement (mean +/- 1.96 SD) were -1.29 to 1.33 l/min and -1.97 to 1.29 l/min, respectively, indicating an acceptable level of agreement. A high reproducibility of the radionuclide technique was found, with a mean difference between determinations by two observers of 0.03 l/min at rest and 0.21 l/min during exercise, the corresponding limits of agreement being -0.75 to 0.81 l/min and -0.79 to 1.21 l/min, respectively. With the aid of a variance component analysis of two determinations by each of four observers, 95% confidence intervals of +/- 10% at rest and +/- 12% during exercise were computed for the radionuclide cardiac output measurements. The observer variation was most pronounced for the part of the cardiac output determination related to measurement of left ventricular equilibrium activity during exercise. First-pass radionuclide cardiography is a reliable method for determination of cardiac output in cardiac patients at rest and during exercise in the upright position.

Aged↗
PubMed1992

Reliability in the interpretation of the course of serum enzyme concentration changes in suspected acute myocardial infarction.

The aim of the study was to determine interobserver variation in the interpretation of the course of serum enzyme concentration changes in suspected acute myocardial infarction. The study was performed retrospectively and had no relation to the treatment of the patients. In 107 patients, two specialists in cardiology, two specialists in internal medicine, and two trainees, independently evaluated courses of enzyme concentrations and decided whether they were suggestive of acute myocardial infarction. Frequency of positive assessments varied for the six observers from 33 to 53% (P less than 0.01). Pairwise comparison of observers showed a median agreement rate of 0.90 (range 0.78 to 0.96). After adjusting for chance agreement a median kappa value of 0.79 (range 0.56-0.92), was achieved. No difference was found in level of agreement between specialists and trainees. Interobserver variation is an important consideration in the interpretation of the course of serum enzyme concentrations and may have an extensive impact on the final diagnosis of acute myocardial infarction.

Adult↗
PubMed1992

Evaluation of left-to-right shunts in adults with atrial septal defect using first-pass radionuclide cardiography.

Non-invasive determination of left-to-right shunts at the atrial level was performed by a new procedure using first-pass radionuclide measurement of cardiac output of the right and left ventricle. In 23 patients with coronary artery disease without shunt the mean difference between the cardiac outputs of the right and left ventricle was 0.04 l.min-1, the limits of agreement -0.80 to 0.88 l.min-1 and the 95% confidence interval for the bias -0.14 to 0.22 l.min-1. Right-sided cardiac catheterization was performed to assess the severity of the arterio-venous shunt by oximetry in 18 adult patients with atrial septal defects. The range of pulmonary-to-systemic flow ratios was 1.4 to 5.0 (mean 2.7) by oximetry and 1.3 to 4.4 (mean 2.5) by the radionuclide technique. The mean difference between flow ratios measured by the two methods was 0.25, the limits of agreement, -0.85 to 1.35 and the 95% confidence intervals for the bias -0.02 to 0.52. In two patients the difference in flow ratios was more than 1. In one of these the oximetric value was more than 2, and the radionuclide value less than 2. The limits of agreement between flow ratios determined by repeated measurements were -1.05 to 0.97, and by two independent observers -0.75 to 0.77. The present findings suggest that first-pass radionuclide determination of left-to-right shunts through atrial septal defects is both reproducible and accurate when compared to the oximetric technique.

Aged↗
PubMed1992

Effects of alpha-adrenoceptor and of combined sympathetic and parasympathetic blockade on cardiac performance and vascular resistance.

1. Cardiac performance and vascular resistance was studied in seven healthy men by radionuclide cardiography and venous plethysmography before and after alpha-adrenoceptor blockade with phentolamine and after combined alpha-adrenoceptor, beta-adrenoceptor (propranolol) and parasympathetic (atropine) blockade. 2. During alpha-adrenoceptor blockade heart rate and cardiac output increased considerably and left ventricular ejection fraction increased because of increased contractility. Systemic vascular resistance fell both during alpha-adrenoceptor blockade alone and during combined blockade. The increase in calf blood flow was of the same magnitude after combined blockade and after alpha-adrenoceptor blockade alone, and was considerably higher than the fall in systemic vascular resistance. Plasma catecholamine concentrations increased after phentolamine, but the changes were blunted when propranolol and atropine were added. 3. These results indicate that peripheral vasoconstriction especially that exerted by alpha-adrenoceptor nervous tone in skeletal muscle restricts left ventricular emptying of the intact heart. During pharmacologic blockade of the sympathetic and parasympathetic nervous system at rest the chronotropic state is augmented, whereas preload and inotropy are unaffected.

Adrenergic alpha-Antagonists↗
PubMed1992

Interpretation of the electrocardiogram in suspected myocardial infarction: a randomized controlled study of the effect of a training programme to reduce interobserver variation.

We examined the effect of a training programme to reduce interobserver variation in interpretation of electrocardiography in suspected myocardial infarction. Sixteen doctors with 6-24 months of clinical training in internal medicine read serial electrocardiographic recordings in 107 patients and assessed whether signs indicative of acute myocardial infarction were present. There was disagreement in approximately 70% of cases. Eight of the doctors were randomly allocated to attend an 8-h intensive course on interpretation of electrocardiography in myocardial infarction. The remaining eight participants were allocated to a control group, received no training, and were not told about the subject of the study. All the doctors then reviewed another series of electrocardiographic recordings. No difference was found in the level of agreement within the two groups before and after the training programme, or between the two groups before and after the training. The raters' ability to discriminate between electrocardiograms with a high and low indication of infarction remained unaffected. We conclude that the training programme did not increase agreement regarding the interpretation of electrocardiographic data in suspected myocardial infarction. Our results suggest that the diagnostic approach of physicians is established at a very early stage in their clinical training. The effect of training programmes should be evaluated by the use of randomized clinical studies.

Education, Medical, Continuing↗
PubMed1992

A comparison of dipyridamole thallium 201 scintigraphy and clinical examination in the determination of cardiac risk before arterial reconstruction.

Preoperative clinical examination, including a 12-lead resting ECG, and planar dipyridamole thallium imaging (DTI) were compared in a prospective study of 65 vascular surgical patients in regard to their value for predicting postoperative cardiac complications. Fifty-three patients underwent abdominal vascular procedures and 12 were operated on for peripheral artery disease. Thirty-six patients had ischemic heart disease (IHD) and/or abnormal findings from 12-lead resting ECG. Of these 36 patients, 11 had nonfatal cardiac complications. The remaining 29 patients were free of IHD and had normal results from ECG. No complications occurred among these 29 patients. There was no postoperative death. Thallium imaging results were abnormal in 45 patients, showing either redistribution and/or scar tissue or low washout. In 18 of these patients major changes with redistribution were present in all projections. Among these patients, 9 had a nonfatal cardiac complication. In the 27 patients with abnormalities in only one or two projections, only 2 had a cardiac event postoperatively. No cardiac complications occurred in patients with normal thallium scintigraphy findings. The patients were operated on irrespective of the results of the scans, and all recovered from any cardiac complications that occurred. In vascular surgical patients with previous IHD and/or abnormal findings from resting ECGs further risk stratification is achieved with DTI.

Adult↗