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Biomedical subjects

H Lindberg

Publications and source records attributed to H Lindberg.

At least 19 recordsLinked to original sources

[Long-term follow-up of patients with congenital heart defects].

There are about 500 new cases of congenital heart disease per year in Norway. Modern diagnostic skills, surgical techniques and follow-up programs have contributed to higher survival rates among patients. Based on international experience, 85-90 per cent of these children will survive into adulthood. Half will suffer from conditions which should be followed up by cardiologists. This article is based upon recommendations on long-term follow-up of patients with congenital heart disease.

Adult↗

Differential recruitment of alpha 1- and beta-adrenoceptors in inotropic control of atrial child myocardium by endogenous noradrenaline.

Noradrenaline release, graded by frequency variation of field stimulation (0.1-2 Hz), in atrial myocardial specimens (n=45) from children (n=21) with congenital heart defects, was used to examine the inotropic responses of graded, receptor-selective, endogenous stimulation. Muscle trabeculae subjected to autonomic blockage by timolol, prazosin and atropine showed a slight positive force-frequency relationship (staircase phenomenon). Blockage by atropine/prazosin (i.e. beta-adrenoceptor stimulation) or atropine/timolol (i.e. alpha1-adrenoceptor stimulation) both resulted in positive inotropic effects. A group of specimens opposed by atropine and primarily subjected to frequency variation, secondly was returned to 1 Hz. Stabilization was followed by sequential reversal by beta-blocker (timolol), alpha 1-adrenoceptor stimulation by exogenous noradrenaline, reversal by alpha 1-blocker (prazosin), and finally supramaximal beta-adrenoceptor stimulation (isoprenaline). The maximal levels of inotropic responses mediated by exogenous alpha 1- and beta-adrenoceptor stimulation was estimated. Analysis of the contraction-relaxation cycles revealed that alpha1- and beta-adrenoceptors were recruited differentially. The alpha1-adrenoceptor mediated, endogenous inotropic effect at 1 Hz was close to the level obtained by exogenous noradrenaline stimulation. In contrast, less than 70% of the beta-adrenoceptor mediated, exogenous inotropic effect was expressed by endogenous noradrenaline at the same stimulating frequency, thus indicating that the alpha1-adrenoceptors may be located closer to the adrenergic nerve terminals than the beta-adrenoceptors. There may be a heterogeneous relationship within the same heart as to the relative distance between the nerve terminals and the adrenoceptors. Spatial localization of adrenergic receptors relative to adrenergic nerve terminals adds another aspect to adrenergic regulation. The alpha1-adrenoceptor pathway may play an important role, especially in low-intensity sympathetic inotropic myocardial control, whereas the beta-adrenoceptor pathway adds important effects to the high-intensity sympathetic regulation. Sympathetic activity may thus tonically stimulate the alpha1-adrenoceptor pathway, without necessarily stimulating the beta-adrenoceptor pathway to the same extent.

Adolescent↗

Outcome of congenital heart defects--a population-based study.

UNLABELLED: In a population-based study including 35,218 infants born alive during the 15-y period 1982-96, 360 (1%) were diagnosed as having a congenital heart defect (CHD). At a follow-up 3-18 y after birth (median 9.5 y) 154 patients (42.8%) were spontaneously cured; of these, 142 (92.2%) had ventricular septal defects (VSDs). Forty-two patients (11.7%) died, 22 of these (52.4%) during the neonatal period (0-28 d after birth). A total of 119 patients (33.1%) underwent therapeutic procedures (surgery, catheter interventions), 24 (20.2%) of whom died. Of the 95 children surviving therapeutic procedures, 54 (56.8%) had their defects completely repaired, while 41 (43.2%) had residual defects or cardiac sequelae, often of minor importance. In 69 children (19.2%) with persistent non-operated defects, 43 (62.3%) had VSDs. A chromosomal disorder, syndrome or associated extracardiac malformation occurred in 72 children (20%). CONCLUSIONS: The study underlines the broad variety in severity of CHDs, with a high neonatal mortality rate as well as a high rate of spontaneous cure. It is estimated that 25% of infants born with a CHD will grow into adult age with persistent non-operated defects, residual defects or cardiac sequelae after therapeutic procedures.

Adolescent↗

Assessment of primary hip osteoarthritis: comparison of radiographic methods using colon radiographs.

OBJECTIVE: To compare the reliability of quantitative measurement of minimum hip joint space with a qualitative global assessment of radiological features for estimating the prevalence of primary osteoarthritis (OA) of the hip in colon radiographs. METHODS: All colon radiographs from patients aged 35 or older, taken at three different radiographic departments in Iceland during the years 1990-96, were examined. A total of 3002 hips in 638 men and 863 women were analysed. Intraobserver and interobserver reliability was assessed by measuring 147 randomly selected radiographs (294 hips) twice by the same observer, and 87 and 98 randomly selected radiographs (174 and 196 hips) by two additional independent observers. Minimum hip joint space was measured with a millimetre ruler, and global assessment of radiological features by a published atlas. RESULTS: With a minimum joint space of 2.5 mm or less as definition for OA, 212 hips were defined as having OA. When the global Kellgren and Lawrence assessment with grade 2 (definite narrowing in the presence of definite osteophytes) or higher as definition for OA was used, 202 hips showed OA. However, only 166 hips were diagnosed as OA with both systems. With 2.0 or 3.0 mm minimum joint space as cut off point, the difference between the two methods increased. Both intrarater and interrater reliability was significantly higher with joint space measurement than with global assessment. CONCLUSIONS: Overall prevalence of radiological OA was similar with the two methods. However, the quantitative measurement of minimum hip joint space had a better within-observer and between-observer reliability than qualitative global assessment of radiographic features of hip OA. It is thus suggested that minimum joint space measurement is a preferable method in epidemiological studies of radiological hip OA.

Adult↗

[Heart transplantation in Norway].

The first heart transplantation in the Nordic countries was performed at Rikshospitalet, Oslo in 1983. In this paper, we present our experience with this treatment up to 1999. 317 heart transplantations have been performed, an average of 23 transplantations per year. 82% of the recipients were males; 50% had heart failure due to coronary heart disease. Mean age of the recipients was 47 years (range 1-64). Our indications and contraindications are similar to most other transplantation centres. Triple immunosuppression with ciclosporin, prednisolone and azathioprine have been used as standard treatment. The survival rate after one and ten years are 85% and 53% respectively, with a significantly higher survival rate among recipients younger than 50 at transplantation, especially if the graft was from a donor younger than 35 years. The most common early postoperative complications were acute cellular rejections and infections. Transplant accelerated coronary heart disease and cancer were the main causes of late death. We believe that close co-operation between Riskshospitalet and local centres will provide the best treatment for patients needing a heart transplant.

Adolescent↗

[Measurements of N-terminal proatrial natriuretic factor in children].

Measurement of plasma levels of natriuretic peptides are now in clinical use in adult patients with heart failure. Experiences in adult medicine cannot be extended to paediatric cardiology due to important physiological differences between adults and children. The haemodynamic background of heart failure in children with congenital heart disease is diverse, and there is no relevant functional or echocardiographic grading system. The authors present results from published studies and summarizes the results of a research project concerning the clinical potential of N-terminal proatrial natriuretic peptide (Nt-proANP) in paediatric cardiology. Peptide levels in newborn children with or without disease are not fully clarified. In children above three months of age, an elevated Nt-proANP value strongly indicates haemodynamic imbalance. This may be important in the follow-up of children with congenital heart disease. A normal value does not exclude the presence of heart disease. A case report illustrates the clinical use of Nt-proANP, and peptide levels in different haemodynamic situations are discussed.

Adult↗

Elevation of atrial natriuretic peptide prohormone. Hemodynamic background of the elevation of N-terminal natriuretic peptide prohormone in children with congenital heart disease.

We postulated previously that variables related to pulmonary flow are independent predictors of levels of atrial natriuretic peptide in children with congenital heart disease. The aim of this study was to test this hypothesis in relation to other hemodynamic and clinical variables. During catheterization we measured the levels of plasma N-terminal atrial natriuretic peptide prohormone in the plasma of 68 children with congenital heart disease. All had undergone complete clinical, echocardiographic and invasive hemodynamic investigations. The influence on the prohormone was analyzed for 10 different variables in a multiple linear regression model. The variability could be explained in large parts (adjusted R2 =77.2%) by variations in atrial pressures or sizes, together with the degree of excessive pulmonary blood flow and signs of heart failure. A value for atrial natriuretic peptide prohormone above 800 pmol/l predicted hemodynamic imbalance (defined as elevated pressures in left or right atrium or the pulmonary arteries, and/or Qp/Qs > 1.5) with a specificity of 94%, a sensitivity of 73%, a positive likelihood ratio of 12.2, and a negative likelihood ratio of 0.29. In conclusion, variables related to pulmonary blood flow are influential determinants of the levels of atrial natriureic peptide in children with congenital heart disease. Atrial pressures, and symptoms of heart failure are also of major importance.

Adolescent↗

Endogenous muscarinic activity attenuates adrenergic inotropic effects in field stimulated atrial myocardium from children with congenital heart defects.

To analyse the possible influence of endogenous muscarinic activity on the inotropic effects of endogenously released noradrenaline in field stimulated myocardial preparations from atria of children with congenital heart defects, we studied the maximal effect of the muscarinic antagonist atropine (1.5 micromol L(-1)). Maximal force of contraction increased by 12.8 +/- 2.0% (SEM), while the maximal rate of development of the force increased by 16.7 +/- 2.7% (SEM). Time to half maximal developed force was 57 +/- 5 s (SEM). Time to peak force, time to relax to the 20% level and relaxation time all decreased significantly after atropine. Compared with endogenous adrenoceptor stimulation alone, the combined effects of partial muscarinic and adrenergic receptor stimulation thus were moderate reductions of the maximal force of contraction and maximal rate of development of the force and increased time to peak force, time to relax to the 20% level and relaxation time. The main effect of the endogenous muscarinic activity probably was to attenuate the effect of the beta-adrenoceptor stimulation. The endogenous muscarinic activity in field stimulated atrial preparations from children is significant, and has to be taken into account in experimental set-ups.

Acetylcholine↗

A pharmacokinetic study of dalteparin (Fragmin) during late pregnancy.

Seventeen women with previously verified thromboembolism were included in a pharmacokinetic evaluation of dalteparin during the third trimester of pregnancy. The bioavailability of morning subcutaneous administration of dalteparin (crossover study) was also compared with that in the evening. Fifteen women injected themselves subcutaneously with 5000 IU and two with 2500 IU dalteparin once daily. An anti-FXa activity of 0.20-0.40 IU/ml 3 h after injection was obtained. The means +/- SD, when comparing morning and evening doses for 5000 IU, were: Cmax 0.21 +/- 0.05 and 0.20 +/- 0.05 IU anti-FXa/ml, AUC 0-24 h 1.97 +/- 0.46 and 1.93 +/- 0.55 IU x h/ml and tmax 3.71 +/- 0.89 and 4.32 +/- 1.60 h, respectively (NS). The two regimens were equivalent. A measurable anticoagulant effect was still observed 16 h after injection of 5000 IU dalteparin. The half-lives after a morning and an evening dose of 5000 IU dalteparin were 4.92 +/- 2.80 and 3.87 +/- 1.15 h, respectively (NS). There were no changes in thrombin marker levels during the two pharmacokinetic measurements.

Adult↗

Thyroid function during and after cardiopulmonary bypass in children.

BACKGROUND: The aim of the study was to elucidate the changes in thyroid function during and after cardiopulmonary bypass (CPB) in children. METHODS: Triiodothronine (T3), thyroxine (T4), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) were determined preoperatively, at specific times throughout CPB, and serially up to 48 h postoperatively, in 10 children (median age 35, range 23-68 months) undergoing elective surgery for congenital heart disease. RESULTS: T3 decreased from 2.01 +/- 0.08 preoperatively to 0.94 +/- 0.10 nmol/l 24 h postoperatively (P < 0.05). T4 levels followed a pattern similar to changes in T3. FT4 increased from 17.4 +/- 0.7 preoperatively to 30.0 +/- 0.4 pmol/l after 30 min of CPB (P < 0.05). TSH decreased from 2.44 +/- 0.43 preoperatively to 0.93 +/- 0.21 24 h postoperatively (P < 0.05). CONCLUSION: T3, T4 and TSH are significantly depressed after open heart surgery in children.

Cardiopulmonary Bypass↗

Thromboprophylaxis with low molecular mass heparin, 'Fragmin' (dalteparin), during pregnancy--a longitudinal safety study.

Twenty-five women with previous verified thromboembolic complications were treated with delteparin (Fragmin) during pregnancy and puerperium. Women with known hereditary thrombophilia (antithrombin, protein C and protein S deficiencies) or with phospholipid antibodies were excluded. The dose at entry was calculated according to body weight and thereafter monitored by anti-FXa activity aiming at 0.20-0.40 IU/ml plasma 3 h post injection. Dalteparin or dextran was used during delivery. Twenty-two women completed the study and 14 of these could be given the same dose throughout pregnancy. There was an increased dose response postpartum. There were no thromboembolic recurrences or severe bleeding complications. The level of antithrombin activity remained normal. Our thrombosis-prone pregnant women had initially increased levels of thrombin markers but no further increase was observed during the dalteparin thromboprophylaxis. Retrospectively, three heterozygous and three homozygous individuals for the FV Leiden mutation leading to activated protein C resistance were identified. In conclusion, dalteparin could safely be used as thromboprophylaxis during pregnancy in these thrombosis-prone women. Women weighing 50-79 kg at entry could be treated with 5000 IU of dalteparin once daily during pregnancy, without monitoring. Postpartum, many of the women were given a reduced dose.

Adult↗

Prevalence of coxarthrosis in an urban population during four decades.

In the current study, in a survey of 4121 double contrast radiographs of the colon performed from 1987 through 1995, the hip joints were examined and classified with regard to the presence or absence of primary coxarthrosis. The data collection was performed in precisely the same manner as in two earlier studies undertaken on 3903 radiographs of the colon covering the years 1956 through 1962 and 4027 radiographs of the colon covering the years 1975 through 1982. In the current study the prevalence of coxarthrosis, the gender ratio, and distribution between bilateral and unilateral cases had not changed compared with the data from the two earlier studies. When pooling the three investigations, the age specific prevalence of primary coxarthrosis based on the 12,051 radiographs fits an exponential curve for which the prevalence of primary coxarthrosis increased from below 1% in the age group younger than 55 years to 10% in the age group older than 85 years. In the current study approximately half of the patients (55%) had undergone total hip arthroplasty. This was more than in the study from 1984 (35%). Among the surgically treated patients, lateral coxarthrosis was more common than was medial coxarthrosis.

Adult↗

[Heart transplantation as a life saving procedure after conventional heart surgery].

The first cardiac transplantation in Norway was performed in November 1983. At the end of 1995 the number of heart transplantations at our institution had reached 238. Five of these patients (2.1%) were transplanted in the early postoperative period of failed conventional cardiac surgery (respectively 20, 26, 54, 84, and 234 hours post surgery). The primary procedure consisted of mitral valve replacement plus left ventricular aneurysm resection, coronary artery bypass grafting, Konz-Konno procedure, aortic valve replacement, and redo coronary artery bypass grafting in patients aged 47, 54, 49, 52, and 43 years respectively. All except one were high-risk patients. All patients were on circulatory support (IABP, LVAD or ECMO) before transplantation. One patient died 12 hours after the transplant due to multiorgan failure that was not reversed by improved pump function. There was one late death four months postoperatively due to severe acute vascular rejection. Three patients are doing well respectively six years, 20 and four months after transplant. We conclude that cardiac transplantation in the early postoperative period of failed conventional heart surgery is an encouraging option in highly selected patients otherwise considered to die in a very short time.

Adult↗

Release of interleukin 6 and activation of complement during and after paediatric cardiopulmonary bypass. Effect of autotransfusion of shed mediastinal blood and ultrafiltration.

Interleukin-6 (IL-6) and the complement activation products C3bc and terminal complement complex (TCC) were measured in three groups of children undergoing open heart surgery. One group was treated with intraoperative extracorporeal ultrafiltration and postoperative autotransfusion of shed mediastinal blood, one group was subjected to autotransfusion only and in one group none of these procedures were performed. No differences between the groups were observed concerning the degree of complement activation. Peak and total accumulated level of IL-6 was significantly higher in the group subjected to ultrafiltration and autotransfusion compared to the group treated conventionally with no interventions. IL-6 may be a sensitive marker of maneuvres increasing the inflammatory load during and after open heart surgery in children.

Biomarkers↗

Release of soluble tumour necrosis factor alpha receptors during and after paediatric cardiopulmonary bypass. Correlation with haemodynamic and clinical variables.

The release of cytokines during cardiopulmonary bypass (CPB) may contribute to haemodynamic alternations encountered after open heart surgery. Regulatory mechanisms exist and include soluble cytokine receptors. We have measured blood levels of tumour necrosis factor (TNF) and its soluble receptor (TNFsr) during and after open heart surgery in children. Correlation analysis to haemodynamic and clinical variables was performed. Using immunoassays the authors registered a significant increase in plasma levels of TNFsr with peak levels 2 h post-operatively at a level of 1702 +/- 170 pg/ml. The concentration of TNFsr remained significantly elevated until 48 h postoperatively but TNF was not significantly elevated. An inverse correlation existed between peak TNFsr and mean arterial pressure (rho = -0.827, P < 0.05), between TNFsr and cardiac index (rho = -0.8, P < 0.05), between TNFsr and left ventricular stroke work index (rho = -0.983, P < 0.01), between TNFsr and weight (rho = -0.85, P < 0.05) and between TNFsr and body surface area (rho = -0.867, P < 0.05). The authors demonstrate that the smallest children experienced the highest TNFsr concentration post-operatively. Furthermore cardiac performance, expressed as cardiac index and left ventricular stroke work index, correlated inversely to peak TNFsr level post-operatively.

Cardiopulmonary Bypass↗

Serum N-terminal proatrial natriuretic factor in children with congenital heart disease.

An objective and simple method of establishing and grading heart failure in children is needed. The N-terminal of the atrial natriuretic factor prohormone, called proANF, is stable in vitro, relatively easy to measure and has been demonstrated as a clinically useful marker of heart failure in adults. We measured proANF in 62 children with congenital heart disease and in 62 age-matched controls, in order to examine the relationship of proANF to different clinical and haemodynamic parameters. Echo Doppler cardiography was performed in all children, and 29 also underwent cardiac catheterization. The children were classified for volume and pressure load in each cardiac chamber, for shunt size and for signs of heart failure. In paediatric patients without cardiac or renal disease, median proANF was 384 pmol.l(-1). In children with congenital heart disease, median proANF was 904 (200-5320) pmol.l(-1) (P < 0.001). The three groups with the highest proANF levels were children with documented high atrial pressure (median proANF 1885 pmol.l(-1)), a large left to right shunt (median proANF 1565 pmol.l-(1)) and moderate or severe heart failure (median proANF 1305 pmol.l(-1)). Furthermore, the proANF level correlated negatively with age and glomerular filtration rate. We conclude that elevation of the proANF level is related to atrial pressures, heart failure and a high pulmonary to systemic flow ratio. These findings make proANF a potential new diagnostic tool in heart disease in children.

Adolescent↗

Left ventricular rupture following external chest compression.

A case of a 62-year-old woman suffering an acute cardiac arrest during a court dispute is presented. Cardiopulmonary resuscitation was immediately started by bystanders. In hospital there were signs of intrathoracic bleeding. A left thoracotomy revealed a cardiac rupture of the left ventricle and a large pericardial tear. Intraoperative evaluation of the heart as well as postoperative enzyme levels and ECG did not indicate acute myocardial infarction. The rupture may therefore be traumatic. The cardiac rupture was sutured five hours after the initial resuscitation, and the patient discharged from the intensive care unit two days after the rupture without clinical signs of neurological injury. A precordial thump is advised before start of external chest compression. One beneficial effect may be that the ventricles empty and the risk of traumatic rupture during compression is reduced.

Cardiopulmonary Resuscitation↗