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Biomedical subjects

J Vanhaecke

Publications and source records attributed to J Vanhaecke.

At least 37 records · Page 2Linked to original sources
PubMed1999

Prognostic significance of exercise versus resting blood pressure in patients with chronic heart failure.

BACKGROUND: Results on the prognostic value of exercise blood pressure differ among studies; this may be related to the characteristics of the studied population. OBJECTIVE: To assess the prognostic significance of blood pressure measured during exercise in patients with chronic heart failure being considered for heart transplantation. DESIGN AND METHODS: Symptom-limited bicycle exercise testing with measurement of blood pressure and respiratory gas analysis was performed in 274 potential candidates for heart transplantation. They were then followed up for mortality and cardiovascular events. RESULTS: Results are given as the mean +/- SD. The age of the patients was 51.5+/-11.0 years, the resting blood pressure was 114+/-20/75+/-12 mmHg, the peak work load was 91+/-33 W and the peak oxygen uptake was 15.1+/-5.0 ml/min per kg. The systolic blood pressure increased to 128+/-21 mmHg at 30 W and to 133+/-23 mmHg at 50% of the peak work load. During the total follow-up time of 513 years, 55 patients died and 145 suffered at least one cardiovascular event. After controlling for age, gender and body mass index, mortality and incidence of events were inversely related to the systolic pressure at 30 W or at 50% of the peak work load, or to both (P < 0.05). The inverse associations of outcome with the systolic pressure at 50% of the peak work load persisted after additional adjustment for resting pressure and for peak oxygen uptake. CONCLUSION: The data indicate that a lower exercise systolic pressure, particularly at 50% of the peak work load, is associated with a higher mortality and a greater incidence of cardiovascular events.

Adolescent↗
PubMed1999

Anomalous origin of a coronary artery in a transplanted heart.

Upon routine coronary angiography one year after surgery in a 62-year-old male recipient of a heart transplant, an abnormal origin of the left anterior descending coronary artery from the pulmonary artery was found in the donor heart. This very rare congenital anomaly had not been detected during harvesting and transplantation of the heart, and to our knowledge it has never been described before in a heart transplant patient. The donor was a 43-year-old male who died of a spontaneous intracranial bleeding. The recipient continues to enjoy a normal functional capacity and is free of anginal complaints, though there is evidence of ischaemia in the left anterior descending artery territory on exercise thallium-201 myocardial perfusion imaging.

Adult↗
PubMed1999

Prediction of peak exercise oxygen uptake by cardiopulmonary measurements at rest in heart transplant candidates.

OBJECTIVE: Peak oxygen uptake (VO2) is a powerful prognostic index, but maximal exercise testing in heart transplant candidates has a number of disadvantages. It is unknown whether it is possible to predict peak VO2 from a comprehensive dataset with parameters of heart and lung function at rest. METHODS: One hundred adult patients in sinus rhythm and with either idiopathic or ischaemic heart failure performed a graded cycle ergometer test until volitional fatigue and underwent radionuclide ventriculography, heart catheterization, and lung function measurements at rest. RESULTS: Weight, height, age, gender and aetiology of heart failure explained 48% of the variance of peak VO2. On top of these anthropometric, demographic and clinical patient characteristics, 12% of the variance of peak VO2 was additionally explained by all resting measurements combined, i.e. radionuclide left ventricular ejection fraction, peak ejection rate, peak filling rate, cardiac frequency, mean right atrial pressure, pulmonary capillary wedge pressure, pulmonary artery pressures, cardiac output, forced vital capacity, forced expiratory volume in one second, and pulmonary diffusing capacity (cumulative R2 = 0.60); among these, pulmonary vascular resistance was the most important predictor (+6%; P < 0.001). Analyses in a subset of 43 male patients pointed out that systemic pressures and vascular resistance were not related to peak VO2. CONCLUSION: On the basis of resting left ventricular function, haemodynamics, and routine pulmonary measurements, it is unlikely to accurately predict exercise tolerance in the majority of heart transplant candidates, i.e. patients with either idiopathic or ischaemic heart failure and able to exercise until exhaustion.

Adult↗
PubMed1998

Oxidized LDL and malondialdehyde-modified LDL in patients with acute coronary syndromes and stable coronary artery disease.

BACKGROUND: The association between oxidative modifications of LDL and coronary artery disease (CAD) is suspected but not established. Therefore, the association between plasma levels of oxidized LDL and malondialdehyde (MDA)-modified LDL and acute coronary syndromes and stable CAD was investigated. METHODS AND RESULTS: The study population contained 63 patients with acute coronary syndromes (45 with acute myocardial infarction and 18 with unstable angina pectoris), 35 nontransplanted patients with angiographically confirmed stable angina, 28 heart transplant patients with posttransplant CAD, 79 heart transplant patients without CAD, and 65 control subjects. After correction for age, sex, and LDL and HDL cholesterol, plasma levels of oxidized LDL and MDA-modified LDL were significantly higher in patients with CAD than in individuals without CAD (r2=0.57 and r2=0.26, respectively; both P=0.0001). Plasma levels of MDA-modified LDL were significantly higher in patients with acute coronary syndromes than in individuals with stable CAD (r2=0.65; P=0.0001) and were associated with increased levels of troponin I and C-reactive protein (r2=0.39 and r2=0.34, respectively; both P=0.0001). Plasma levels of oxidized LDL were not associated with increased levels of troponin I and C-reactive protein (r2=0.089 and r2=0.063, respectively). CONCLUSIONS: Elevated plasma levels of oxidized LDL are associated with CAD. Elevated plasma levels of MDA-modified LDL suggest plaque instability and may be useful for the identification of patients with acute coronary syndromes.

Aged↗
PubMed1998

Frequency dependence of Ca2+ release from the sarcoplasmic reticulum in human ventricular myocytes from end-stage heart failure.

OBJECTIVES: Human cardiac muscle from failing heart shows a decrease in active tension development and a rise in diastolic tension at stimulation frequencies above 50-60 beats/min due to both systolic and diastolic dysfunction. We have investigated underlying changes in cellular [Ca2+]i regulation. METHODS: Single ventricular myocytes were isolated enzymatically from the explanted hearts of transplant recipients with ischemic cardiomyopathy (nhearts = 5 ncells = 15) or dilated cardiomyopathy (nhearts = 6, ncells = 19). Cells were studied during whole-cell patch clamp with fluo-3 and fura-red as [Ca2+]i indicators (36 +/- 1 degrees C). RESULTS: In current clamp mode (action potential recording), the amplitude of Ca2+ release from the sarcoplasmic reticulum (SR) decreased at stimulation frequencies above 0.5 Hz; this decrease was more pronounced for cells from dilated cardiomyopathy. Diastolic [Ca2+]i increased at 1 and 2 Hz for both groups. Action potential duration (APD90) decreased with frequency in all cells; in addition there was a drop in plateau potential of 10 +/- 1 mV for cells from ischemic cardiomyopathy and of 13 +/- 2 mV for cells from dilated cardiomyopathy. In voltage clamp mode the L-type Ca2+ current showed reversible decrease during stimulation at 1 and 2 Hz. Recovery from inactivation during a double pulse protocol was slow (75 +/- 3% at 500 ms, 89 +/- 3% at 1000 ms) and followed the decay of the [Ca2+]i transient. CONCLUSIONS: The negative force-frequency relation of the failing human heart is due to a decrease in Ca2+ release of the cardiac myocytes at frequencies > or = 0.5 Hz, more pronounced in dilated than in ischemic cardiomyopathy. Inhibition of ICaL at higher frequencies, at least partially related to an increase in diastolic [Ca2+]i, will contribute to this negative staircase because of a decrease in the trigger for Ca2+ release, and of decreased loading of the SR.

Action Potentials↗
PubMed1998

Oxidized low density lipoproteins in patients with transplant-associated coronary artery disease.

The monoclonal antibody 4E6-based ELISA was used to quantify levels of oxidized LDL in plasma of 65 control subjects, 47 patients transplanted for dilated cardiomyopathy (DCM), and 60 patients transplanted for coronary artery disease (CAD). Levels of oxidized LDL were 0.68+/-0.039 mg/dL (mean+/-SEM), 1.27+/-0.14 mg/dL (P<.001 versus control), and 1.73+/-0.13 mg/dL (P<.001 versus control and <0.01 versus DCM), respectively. Levels of oxidized LDL were significantly lower in transplanted patients with angiographically normal coronary arteries (grade 0, 1.16+/-0.053 mg/dL; n=79) than in patients with mild (grade 1, 2.13+/-0.30 mg/dL; n=18; P<.001 versus grade 0) or severe (grade 2, 3.18+/-0.45 mg/dL; n=10; P<.001 versus grade 0 and P<.05 versus grade 1) coronary artery stenosis. Logistic regression analysis identified three parameters that were significantly and independently correlated with posttransplant CAD: plasma levels of oxidized LDL (P=.0001), length of follow-up (P=.0008), and donor age (P=.047). Thus, the present study demonstrates that plasma levels of oxidized LDL correlate with the extent of CAD in heart transplant patients and suggests that elevated levels of oxidized LDL may be a marker for CAD.

Coronary Disease↗
PubMed1998

Late acute rejection and subclinical noncompliance with cyclosporine therapy in heart transplant recipients.

BACKGROUND: Although noncompliance with immunosuppressive medication is recognized as a critical behavioral risk factor for late acute rejection episodes and graft loss after transplantation, little is known about the degree of subclinical cyclosporine noncompliance, its associated risk for acute late rejection episodes (>1 year after transplantation), and its determinants in heart transplant recipients. METHODS: The convenience sample of this longitudinal study included 101 European heart transplant recipients (87 men and 14 women), with a median age of 56 (Q1 = 50, Q3 = 61) and a median posttransplantation status of 3 (range 1 to 6) years. Subclinical cyclosporine noncompliance was measured during a 3-month period with electronic event monitoring. Selected sociodemographic, behavioral, cognitive, emotional, health, and treatment-related determinants of medication noncompliance were measured by using instruments with established psychometric properties or by patient interviews. With the use of iterative partitioning methods of cluster analysis, including nonstandardized electronic event monitoring compliance parameters, patients were categorized by degree of subclinical cyclosporine noncompliance into a 3-cluster solution. RESULTS: Overall compliance was high, with a median medication taking compliance of 99.4%. The 3 derived clusters, that is, excellent compliers (84%), minor subclinical noncompliers (7%), and moderate subclinical noncompliers (9%), differed significantly by degree of subclinical noncompliance (p < .0001) and showed a 1.19%, 14.28%, and 22.22% incidence of late acute rejections (p = .01), respectively. The 3 groups also differed in terms of former medication noncompliance (p = .02), appointment noncompliance (p = .03), and perceived self-efficacy with medication taking (p = .04). CONCLUSIONS: Although in absolute numbers cyclosporine compliance in this sample was high, minor deviations from dosing schedule were associated with an increased risk for acute late rejection episodes. This suggests a pivotal role of patient compliance in successful long-term outcome after transplantation.

Acute Disease↗
PubMed1997

Impact of age and gender on peak oxygen uptake in chronic heart failure.

Anthropometric and demographic characteristics are important determinants of exercise performance in healthy subjects, but their influence has not yet been studied in severe chronic heart failure, although peak oxygen uptake is frequently assessed in such patients for prognostic purposes. The aim of the present analysis was to examine the association between peak oxygen uptake and age, gender, and measures of body size in patients with severe chronic heart failure. We selected 122 (99 male) adult heart transplant candidates who were able to perform a bicycle ergometer test with respiratory gas analysis until voluntary fatigue. Peak oxygen uptake was higher in male than in female patients, both before and after adjustment for weight. In single regression analysis on the total study population, peak oxygen uptake was positively related to weight and to height, but inversely to age (r = 0.59 (P < 0.001), 0.42 (P < 0.001), and -0.33 (P < 0.001), respectively). Multiple stepwise regression analysis identified weight (P < 0.001), age (P < 0.001), and gender (P < 0.01) as independent determinants of peak oxygen uptake (cumulative R2 = 0.45). Similar to the findings in healthy subjects, peak oxygen uptake of patients with severe chronic heart failure is influenced by anthropometric and demographic characteristics.

Adult↗
PubMed1997

Atrial fibrillation is associated with a lower exercise capacity in male chronic heart failure patients.

OBJECTIVE: To study the influence of atrial fibrillation on peak oxygen uptake (peak VO2) in chronic heart failure. An unfavourable effect of atrial fibrillation has been shown in several patient populations, but the results have not been consistent in chronic heart failure. METHODS: Data were analysed from male heart transplant candidates who were able to perform graded bicycle ergometry until exhaustion with respiratory gas analysis and measurement of heart rate. Patients in atrial fibrillation (n = 18) were compared with patients in sinus rhythm (n = 93). RESULTS: Age, weight, height, and aetiology of chronic heart failure did not differ significantly between the two groups. Cardiac catheterisation at supine rest showed that heart rate was comparable, but that stroke volume and cardiac output were lower (p < 0.05) in atrial fibrillation. Systolic and diastolic left ventricular function, assessed by radionuclide angiography at rest, were not significantly different. Peak VO2 (mean (SD): 13.8 (3.6) v 17.1 (5.6) ml/kg/min; p < 0.01) and peak work load (78 (27) v 98 (36) W; p < 0.05) were lower in the patients with atrial fibrillation, though respiratory gas exchange ratio and Borg score were similar in the two groups. Patients with atrial fibrillation had a higher heart rate sitting at rest before exercise (93 (16) v 84 (16) beats/min) and at peak effort (156 (23) v 140 (25) beats/min) (p < 0.05). CONCLUSIONS: Atrial fibrillation is associated with a 20% lower peak VO2 in patients with chronic heart failure, suggesting that preserved atrial contraction or a regular rhythm, or both, are critical to maintain cardiac output and exercise performance.

Adult↗
PubMed1997

[Beta-blockers in cardiac insufficiency].

This article reviews the information derived from various large-scale multicentre studies, summarizes current concepts concerning the mechanisms of action of beta-blockers in heart failure and recalls their modalities of use in this indication. A beneficial effect of beta-blockers on survival has not yet been formally demonstrated. However, the promising results of preliminary trials and progress in the concepts concerning the mechanism of action of beta-blockers suggest that ongoing studies will eliminate any doubts concerning this favourable effect. The action of beta-blockers in heart failure has not yet been entirely elucidated. The multiple mechanisms proposed are situated at various levels, from the organ itself to the subcellular and molecular level. Recent ideas concerning reverse remodelling of the ventricle, correction of altered genetic expression and protection against apoptosis are interdependent and particularly fascinating. The practical use of beta-blockers in this indication is specific and implementation of this treatment requires compliance with several rules, the most important of which are to start treatment at very low doses and to increase the dosage only very gradually.

Adrenergic beta-Antagonists↗
PubMed1996

Survival analysis and clinical medicine. An observational comparison of the implantable cardioverter defibrillator, amiodarone treatment, and heart transplantation.

In clinical practice, observational studies remain necessary for evaluating accepted and new treatments. The comparison of results remains difficult and often controversial, because of a wide variation in clinical characteristics. Survival analysis and calculation of the standardized mortality ratio offer the possibility to compare outcomes in different study groups. We have applied these techniques to an observational comparison of outcomes in three groups of patients, followed in two university centres: (i) patients treated with an implantable cardioverter defibrillator; (ii) patients under amiodarone treatment; and (iii) recipients of a heart transplant. There was no statistically significant difference in the cumulative survival from total mortality. The standardized mortality ratio revealed the different natural history of patients undergoing heart transplantation.

Age Distribution↗
PubMed1996

Heart rate variability after cardiac transplantation in humans.

The reappearance of cardiac innervation after cardiac transplantation remains a matter of debate. We evaluated the ability of heart rate variability (HRV) analysis to detect the extent and time course of functional cardiac allograft reinnervation. Time- and frequency-domain analysis of heart rate was performed on Holter recordings of 120 heart transplant and four heart-lung transplant recipients. A high frequency (HF) component was clearly distinguished on visual inspection of power spectral density in 42 patients. In eight patients an HF component of normal magnitude was detected. The other 34 patients in this group, including all four heart-lung transplants, presented with a very small HF component. The other 82 patients showed a flat spectrum. The group with an HF component of normal amplitude was significantly different, compared to the other groups, for all HRV parameters. Serial plotting of HRV parameters of the patients with an HF component of normal amplitude against time posttransplant, revealed, from 12 months onwards, a progressive increase of parameters denoting HF variability. In five heart transplant patients with acute allograft rejection, the use of HRV analysis for rejection monitoring was unsuccessful. These results suggest that, inasmuch as the HF component of HRV is caused by parasympathetic cardiac innervation, the HF component of normal amplitude, observed in only a minority of cardiac transplant recipients (6%), is a marker for parasympathetic reinnervation. The evolution over time of this HF component is compatible with a biological phenomenon as gradual parasympathetic reinnervation of the sinus node.

Autonomic Nervous System↗
PubMed1995

Timing and quantification of bone loss in cardiac transplant recipients.

To evaluate osteopenic bone disease in heart transplant patients, we prospectively measured bone mineral density (BMD) in 33 consecutive male recipients before hospital discharge and 1 year later, using dual photon absorptiometry. At hospital discharge BMD measurement at the lumbar spine was 90% of that expected in healthy age- and sex-matched controls (p = 0.005). One year later BMD had further decreased by 8.5% at the lumber spine and by 10.4% at the femoral neck (P = 0.0001). Five patients suffered vertebral compression fractures during the 1st postoperative year. Our results indicate that osteopenia of the lumbar spine is already present at the time of hospital discharge after transplantation and that further bone loss occurs at considerable rate during the 1st postoperative year at the lumber spine and at the femoral neck.

Adult↗
PubMed1995

Metabolism of nitrogen-13 labelled ammonia in different conditions in dogs, human volunteers and transplant patients.

To investigate the rate of metabolism of nitrogen-13 labelled ammonia (13NH3) in different conditions, we have determined the relative amount of unchanged 13NH3 in the blood of dogs, volunteers and transplant patients at different times following injection. In dogs, the determinations were made under basal conditions, during adenosine administration and after coronary occlusion. The results show that adenosine administration increases the metabolic rate whereas coronary occlusion does not affect 13NH3 metabolism. For both human volunteers and transplant patients the metabolic rate of 13NH3 was assessed under basal conditions and during adenosine administration. 13NH3 metabolism proceeds faster in transplant patients than in volunteers under both conditions. Adenosine administration causes a faster 13NH3 turnover in volunteers but not in transplant patients. Application of individual metabolite correction resulted in a 16% decrease in the calculated blood flow compared to uncorrected values. A smaller difference (5%) was observed between correction with mean metabolite values and individually acquired metabolite values.

Adenosine↗
PubMed1995

Theophylline increases oxygen consumption during inspiratory resistive loading.

The effect of theophylline on diaphragmatic blood flow (Qdi) and oxygen consumption (VO2di) was studied in eight lightly anesthetized dogs during quiet breathing and inspiratory resistive loading. Qdi was determined with the radioactive microsphere tracer technique, and VO2di was calculated as the product of Qdi and the diaphragmatic arterio-venous oxygen difference. During quiet breathing, theophylline increased minute ventilation (9.3 +/- 1.7 versus 5.1 +/- 0.4 L/min), mean inspiratory flow (547 +/- 60 versus 378 +/- 56 ml/s), and duty cycle (0.270 +/- 0.042 versus 0.192 +/- 0.024) but did not significantly alter Qdi or VO2di. Conversely, Qdi increased significantly during loaded breathing compared with quiet breathing (37 +/- 4 versus 27 +/- 3 ml/100 g/min) and was further increased by theophylline (45 +/- 7 ml/100 g/min). Theophylline did not alter the tension-time index of the diaphragm (TTdi) during inspiratory resistive loading (0.054 +/- 0.006 versus 0.056 +/- 0.004, p NS) but resulted in a disproportionate and significant increase in VO2di (2.66 +/- 0.53 versus 1.78 +/- 0.26 ml/100 g/min). Similarly, total-body oxygen consumption (VO2TB) during inspiratory loading increased significantly after theophylline (24%), but the tension-time index of the inspiratory muscles (TTi), a measure of the total respiratory load, was unchanged. We conclude that theophylline significantly increases VO2di and VO2TB at the same TTdi and TTi during resistive loading. This enhanced energy expenditure needs consideration in the clinical management of pulmonary disorders that increase the work of breathing.

Animals↗
PubMed1995

Signs of functional efferent reinnervation of the heart in patients after cardiac transplantation.

Short-term heart rate and blood pressure variability were assessed in 62 patients, studied within 1 month, at 1, at 2 or at 3-5 years after cardiac transplantation and in 13 healthy control subjects. Means and total variances were calculated and the powers of the low frequency (LF, 0.07-0.14 EqHz) and of the high frequency (HF, 0.14-0.35 EqHz) components were derived from power spectral analysis. Mean heart period, its total variance and the powers of the LF and HF components were lower in the transplanted patients than in the controls (P < 0.001). The total variance and the LF and HF powers differed significantly among the groups of transplanted patients (P < 0.01) and intergroup comparison showed significantly higher values in patients 3-5 years after transplantation than in those studied within 1 month. The variance of systolic blood pressure and its power spectrum did not differ between patients and controls. The results suggest that partial functional reinnervation of the sinus node occurs after heart transplantation in man.

Blood Pressure↗