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Biomedical subjects

W Daenen

Publications and source records attributed to W Daenen.

At least 55 records · Page 3Linked to original sources
PubMed1996

Prevention of bone loss in cardiac transplant recipients. A comparison of biphosphonates and vitamin D.

Bone mineral density is already abnormally reduced at the moment of cardiac transplantation and bone loss occurs at an impressive rate in the first postoperative year. The aim of the study was to compare two prophylactic medical regimens as to their efficacy in mitigating bone loss after transplantation. Forty-eight consecutive recipients were randomized to receive either alternating calcium carbonate and disodium etidronate (group A) or a daily supplement of calcium carbonate and alphacalcidol (group B). Bone mineral density measurements were performed immediately before hospital discharge and 6, 12, and 24 months after surgery using dual energy X-ray absorptiometry. Clinical events were recorded and roentgenograms of the spine were performed postoperatively and 1 and 2 years later. In both treatment groups bone loss remained significant at the level of the lumbar spine in the first postoperative year (P<0.005) and at the level of the femoral neck in the first (P<0.005) and the second (P<0.06) year after transplantation. Six months after transplantation, however, patients receiving alphacalcidol had a significant reduction in bone loss at the level of the lumbar spine (P=0.047) and at the level of the femoral neck (P=0.043). At the level of the femoral neck this decrease in bone loss was even more pronounced in the second postoperative year (P<0.001). In the group of patients treated with disodium etidronate, 4 recipients needed additional hospitalizations for treatment of symptomatic fractures at the level of the lumbar spine or the femoral neck. No such events happened in recipients receiving vitamin D supplements. Prophylactic administration of calcium carbonate and alphacalcidol after cardiac transplantation reduces bone loss and seems to decrease osteoporotic complications.

Calcium↗
PubMed1996

Rhythm disturbances after mitral valve surgery: comparison between left atrial and extended trans-septal approach.

This study was undertaken to determine the incidence of postoperative arrhythmias in mitral valve surgery through the left atrium as compared with the extended trans-septal approach. All patients undergoing mitral valve surgery for acquired valve disease between 1 January 1991 and 31 December 1993 were reviewed. Only patients with preoperative normal sinus rhythm were included in this study. End-points for analysis were: 'any supraventricular arrhythmia'; 'atrial fibrillation of flutter'; and 'ectopic atrial or junctional rhythm'. All predictive factors with a P-value < 0.10 in univariate analysis were entered into the multivariate proportional hazard model of Cox. Some 72 patients were included for analysis. No variables were independently predictive of 'any supraventricular arrhythmia'. Age is an independent predictor of 'atrial fibrillation or flutter' and surgical approach of 'ectopic atrial or junctional rhythm'.

Adult↗
PubMed1996

Hemodynamic performance of the PRIMA Edwards stentless aortic xenograft: early results of a multicenter clinical trial.

Between June 1991 and July 1993, 200 PRIMA Edwards stentless aortic bioprostheses were implanted in 4 European centres. Mean age of the group was 68.5 years (S.D. 8.0). The subcoronary implantation technique was used in 161 patients, the inclusion cylinder technique in 39 patients. Valve diameters ranged from 19 mm to 29 mm. Transthoracic Doppler echocardiographic studies were performed at discharge, and after 6 months and 12 months; a complete one-year follow-up was obtained. At 12 months peak systolic gradients ranged from 35.2 mmHg (19 mm valve) to 10.9 mmHg (29 mm valve) and effective orifice area ranged from 0.8 cm2 (19 mm valve) to 2.8 cm2 (29 mm valve). 30-day mortality was 3%, 12-month mortality was 5%. Complications were thrombo-embolism in six patients (3%), haemorrhage in three patients (1.5%), endocarditis in two patients (1%), and total AV-block requiring an endocavitary pacemaker in 14 patients (7%). At one year aortic regurgitation was evident in 27% patients but only one patient showed grade III. The stentless xenograft still offers good hemodynamics at one year. Morbidity and mortality are acceptable. Evaluation of the long-term performance of this new type of xenograft will be an important issue in future.

Adult↗
PubMed1996

Dynamics of respiratory gas exchange during exercise after correction of congenital heart disease.

In pediatric exercise testing, conventional measures of aerobic exercise function such as maximal O2 uptake or the ventilatory anaerobic threshold (VAT) use only one value for the assessment of exercise capacity. We studied a more comprehensive approach to evaluate aerobic exercise function by analyzing the steepness of the slope of CO2 production (VCO2) vs. VO2 above the VAT (S3). This was calculated in 32 patients operated on for congenital heart disease [16 for transposition of the great arteries (TGA) and 16 for tetralogy of Fallot (TF)] and was compared with 16 age-matched controls (nl). The results show that the reproducibility of this new assessment method was excellent (coefficient of variation for S3: 8.6%). S3 was significantly steeper (P<0.05) in the patients (1.31 +/- 0.22 for TGA and 1.28 +/- 0.16 for TF) compared with the nl (1.10 +/- 0.22). Also, the difference between S3 and the slope of VCO2 vs. VO2 below the VAT was significantly higher in the patients (0.37 +/- 0.22 for TGA and 0.31 +/- 0.10 for TF) than in controls (0.22 +/- 0.06). The steeper slopes were associated with lower than normal values for VAT and O2 during exercise. It is concluded that the analysis of the steepness of the slope of CO2 is a sensitive, reproducible, and objective approach to evaluate the integrative cardiopulmonary response to exercise. It complements the assessment of a subnormal VAT by reflecting the extent of anaerobic metabolism.

Aerobiosis↗
PubMed1996

Aortic and mitral valve disease induced by ergotamine therapy for migraine: a case report and review of the literature.

A case of aortic and mitral valve disease associated with ergotamine abuse is reported. A 34-year-old woman presented with dyspnea after a long standing history of peripheral vascular pathology associated with ergotamine abuse. Cardiac dysfunction was rapidly progressive. At surgery, nodular thickening of both valves and fusion of the posterior leaflet of the mitral valve were seen. Microscopy revealed proliferation of myofibroblasts with little destruction of normal valvular elements. The similarity to lesions in carcinoid heart disease and in methysergide-associated valvular disease suggests direct stimulation of myofibroblast growth by serotonin agonist effect.

Adult↗
PubMed1996

Clinical and cost comparison of three postoperative skin preparation protocols in CABG patients.

This descriptive pilot study includes a clinical and cost comparison of three preoperative skin preparation protocols (razor, clipper, and depilatory cream, in combination with whole body disinfection) in 82 patients undergoing coronary artery bypass graft (CABG) surgery. The clinical research protocol included an evaluation of body surface area, index of body hair growth, depilatory effect, skin integrity after depilation, and side effects of body disinfection with chlorhexidine solution, as well as protocol-specific evaluation criteria. The cost comparison was performed by keeping a record of the materials used and the workload for each separate activity associated with the three preoperative skin preparation protocols. Material and labor costs were calculated for each of the different aspects of the protocols. Clinical evaluation revealed that the clipper protocol (if necessary, in combination with cream depilation) is most convenient for depilation of patients with heavy hair growth. The depilatory cream protocol is an appropriate method to depilate patients with slight or moderate hair growth. The razor method should be eliminated from clinical practice due to previous documented evidence of an associated increased risk of postoperative wound infection. Cost calculations revealed that the median hospital cost (standardized for differences in hair growth index, working hours and nurse qualification levels) of the razor, clipper, and cream protocols is $6.13, $9.84, and $8.16 (U.S. dollars), respectively. In 1995, yearly raw (i.e. non-standardized) hospital costs for the three procedures were $14,402, $16,114, and $16,765, respectively, with 708 CABG procedures performed. Although changing to a clipper and/or cream protocol may be associated with an initial, although moderate, increase in hospital costs, compared to the razor method, substantial cost savings could be expected long-term. The superiority of these protocols is primarily due to a decreased incidence of postoperative wound infections, as compared to that associated with the razor protocol.

Aged↗
PubMed1995

Comparison by computerized numeric modeling of energy losses in different Fontan connections.

BACKGROUND: Different surgical techniques for creating a Fontan circulation can be used. The option of including an atrium in the circuit, or the technique used for connecting the caval veins to the pulmonary artery in a total cavopulmonary connection, frequently is empirical and is based on personal experience and preference. The hemodynamic and energetic differences between the different circuits are small, and short-term results are comparable. However, small, energetic differences may have significant implications for the long-term follow-up. The finite element method allows a computer-based modeling of the flow dynamics and pressure losses. It permits comparison of different Fontan connections in a single patient with identical geometry and functional conditions. METHODS AND RESULTS: We compared the atriopulmonary connection with different types of cavopulmonary connections, which differed in the degree of symmetry of implantation of both caval veins into the right pulmonary artery. Based on anatomic models and physiological flow dynamics, three-dimensional geometries and finite element meshes were created with PATRAN; flows were calculated with POLYFLOW (B), and results were visualized with DATA VISUALIZER. CONCLUSIONS: The atriopulmonary connection produces higher energy losses than the cavopulmonary connection (+/- 1 mm Hg at rest). The cavopulmonary connection is more efficient when the connection of the caval veins to the pulmonary artery is asymmetrical.

Blood Flow Velocity↗
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

Serial cardiorespiratory exercise testing in patients with congenital heart disease.

Aerobic capacity of patients with different forms of congenital heart disease was serially evaluated in 79 patients and the evolution was correlated with the lesion and the level of daily activity. The patients were divided into six groups: patients with a small ventricular septal defect (VSD) with mini shunt (n = 14), mild pulmonary valve stenosis with gradient < 40 mm Hg (PS) (n = 12), mild to moderate aortic valve stenosis (gradient 36 +/- 17 mmHg) (AS) (n = 12), patients 4.7 +/- 2.1 years after repair of tetralogy of Fallot (PO-TF) (n = 16), patients 2.2 +/- 2.9 years after closure of a high flow/high gradient VSD (PO-VSD) (n = 13), and patients 2.6 +/- 1.7 years after Fontan repair (Fontan-PO) (n = 12). Aerobic capacity was assessed by determination of the ventilatory anaerobic threshold (VAT). VAT reflects the highest aerobic exercise level prior to a disproportionate increase of CO2 and ventilation relative to O2 uptake; it is independent of patient motivation. Data are expressed as percentage of normal O2 uptake at VAT, determined in 234 age/gender matched controls. The habitual level of physical activity was assessed by a standardised questionnaire. Aerobic capacity in all subgroups of patients, even with very mild defects, was at or below the lower limit of normal. Children left unrestricted from physical exercise (VSD, PS, PO-VSD) had no change over the study period. However, aerobic capacity of patients with medically imposed physical restrictions (AS) and significant residual haemodynamic lesions (PO-TF, Fontan) decreased with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Transverse arch hypoplasia predisposes to aneurysm formation at the repair site after patch angioplasty for coarctation of the aorta.

OBJECTIVES: This study used magnetic resonance imaging (MRI) to evaluate the morphology and pathophysiology of aneurysm formation after patch angioplasty for coarctation of the aorta. BACKGROUND: Late aneurysm formation at the repair site is a well known and frequent complication after patch angioplasty. However, because the underlying mechanisms remain unresolved, postoperative outcome is unpredictable and adequate follow-up difficult. METHODS: Seventy-three of 85 patients with patch angioplasty for coarctation of the aorta were screened for aneurysm formation. Magnetic resonance imaging was performed in all 33 patients with an aneurysm, and results were compared with those for 13 control patients and 10 normal subjects. Mean (+/- SD) time between operation and MRI was 12.0 +/- 2.0 years. Aneurysm was defined as the ratio of the diameter of the aorta at the repair site to the diaphragmatic aorta > or = 1.5. Hypoplasia of the transverse arch and recoarctation at the repair site were defined as a ratio < 0.9. Transverse arch ratios on MRI were compared with those on preoperative cineangiography and the pressure gradient between the patient's right and left arm. RESULTS: All 33 patients with an aneurysm had a hypoplastic transverse arch. The 13 patients with a normal ratio at the repair site had a normal transverse arch ratio (chi square, p < 0.0001). Logarithmic regression showed a significant negative correlation (r = 0.62) between the repair site and transverse arch ratios. A significant pressure difference between the patient's right and left arm was found in patients with versus those without aneurysm (p = 0.0009). No significant difference was found between transverse arch ratios on preoperative cineangiography and postoperative MRI (mean 0.014 +/- 0.1, p = 0.4). CONCLUSIONS: Aneurysm formation at the repair site is highly related to hypoplasia of the transverse arch. Sufficient catch-up growth of a hypoplastic transverse arch is rare after late patch angioplasty. Dynamic phenomena, such as flow acceleration and turbulence, originating in a narrow transverse arch, may contribute to aneurysm formation at the repair site after patch angioplasty.

Adolescent↗
PubMed1995

Isolated right ventricular unloading for postcardiotomy right ventricular failure in a child.

Severe right ventricular (RV) failure after total correction of double outlet RV (DORV) with pulmonary atresia was completely reversed with extracorporeal mechanical RV unloading in a 2.5-year-old child. The patient could be weaned after 168 h of RV assist device (RVAD) support using a centrifugal Bio-Medicus pump and was discharged from the hospital without adverse effects. This experience of isolated RV unloading in a child encourages further application of RVAD in pediatric patients.

Cardiopulmonary Bypass↗
PubMed1995

Right ventricular outflow reconstruction with homografts.

Ninety children and young adults underwent right ventricular outflow tract (RVOT) reconstruction with aortic or pulmonary homografts from May, 1989 to May, 1994. The patients were divided into three groups according to preoperative diagnosis: RVOT obstructions with ventriculo-arterial (VA) concordance (61), RVOT obstructions with VA discordance (18) and truncus arteriosus (11). Of the reconstructions, 52% were reoperations. A pulmonary homograft was used by preference (85% in the concordant group and 33% in the discordant group). One patient died after homograft correction (hospital mortality 1.1%). The mean follow-up was 32 +/- 22 months. One patient died after 10 months due to congestive heart failure and obstructive pulmonary hypertension. All other patients were in NYHA classes I-II. Three patients (two discordant and one truncus correction) underwent reoperation because of aortic homograft dysfunction and calcification. The incidence of significant (> or = 40 mmHg) gradient across the reconstruction found at the last echocardiographic control was 4% in the concordant, 28% in the discordant, and 18% in the truncus, group. Echocardiographic evidence of moderate (grade 2-3/4) pulmonary regurgitation (PR) was noticed in 24 and 13% of the concordant and discordant groups, respectively. From this medium-term experience it is concluded that (1) the medium-term performance of cryopreserved homografts is excellent, even in young patients, (2) corrections in patients with VA discordance need close follow-up, (3) the use of pulmonary homografts, especially in VA concordant lesions, should be encouraged, (4) longer-term follow-up is necessary to confirm the superiority of the cryopreserved homograft when compared to the porcine xenograft in the RVOT.

Adolescent↗
PubMed1995

Dopamine suppresses thyroid-stimulating hormone secretion in neonatal hypothyroidism.

The infusion of dopamine, a hypophysiotropic catecholamine, which inhibits release of thyroid stimulating hormone (TSH), is the inotropic therapy of first choice in neonatal intensive care. Newborns with primary hypothyroidism are at increased risk of cardiocirculatory morbidity and are screened by measuring serum TSH concentrations. In an infant with both congenital heart disease and neonatal hypothyroidism, withdrawal of dopamine infusion was documented to evoke a doubling of serum TSH levels within 40 min, a finding suggestive of an inhibitory effect of dopamine administration on neonatal TSH hypersecretion. As a result, dopamine therapy may be a pitfall in TSH screening for neonatal hypothyroidism.

Congenital Hypothyroidism↗
PubMed1994

Safety and efficacy of low dose simvastatin in cardiac transplant recipients treated with cyclosporine.

Hyperlipidemia is common in heart transplant patients. Lipid-lowering therapy poses special problems, yet may be important because accelerated graft atherosclerosis is the major factor limiting long-term survival. Simvastatin 5 mg/day was started > 6 months after surgery in 26 consecutive cardiac transplant recipients with a total serum cholesterol level of > 250 mg/dl. The dose of simvastatin was increased in 5-mg increments until total serum cholesterol fell below 220 mg/dl or until side effects developed or up to a maximal dose of 20 mg/day. The final average daily dose was 10 mg. Changes in serum lipid levels after 6 months of therapy were compared with data from a matched and concurrent control group of heart transplant patients not taking simvastatin. Immunosuppression for both groups consisted of CsA, AZA, and corticosteroids. In the simvastatin-treated group, the serum level of total cholesterol decreased by 27% from 315 +/- 53 to 230 +/- 38 mg/dl (P < 0.0001), low density lipoprotein cholesterol decreased by 40% from 205 +/- 30 to 123 +/- 32 mg/dl (P < 0.0001), and triglycerides decreased by 21% from 177 +/- 89 to 140 +/- 49 mg/dl (P < 0.01). There was no significant change in high density lipoprotein cholesterol level. Body weight and CsA blood levels remained stable. Steroid intake decreased during the study period to a similar extent in both the treated and the control groups. In the control group, no significant changes in serum lipid levels were observed. Two patients experienced a mild form of myotoxicity. In one other patient simvastatin treatment was stopped after an acute pancreatitis of uncertain etiology developed. Low dose simvastatin effectively lowers total serum cholesterol, low density lipoprotein cholesterol, and triglycerides in heart transplant patients. With due precautions, the safety profile of the drug in this patient population seems reasonable.

Anticholesteremic Agents↗
PubMed1994

ALCAPA syndrome: an example of chronic myocardial hypoperfusion?

OBJECTIVES: The purpose of this study was to evaluate functional variables and morphologic correlates of chronically hypoperfused myocardium before and after revascularization. BACKGROUND: Neonates with congenital anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA syndrome) develop some myocardial necrosis shortly after birth. The survivors of this event are left with a localized infarction and an almost entirely collateral circulation-dependent perfusion of the left ventricle that results in poor global left ventricular function. Survival beyond infancy is uncommon because of severe left heart failure. Revascularization, however, brings about functional recovery with good clinical outcome. The ALCAPA syndrome is thus characterized by chronic collateral circulation-dependent low perfusion, low contraction matching and potential revivability. METHODS: Five patients with ALCAPA syndrome are presented, with preoperative and postoperative clinical findings and histologic data obtained from intraoperative transmural biopsy specimens. RESULTS: The angiographically assessed preoperative ejection fraction was 33 +/- 19% (mean +/- SD). Postoperative echocardiographic follow-up revealed normal left ventricular function in all patients. Histologic study of the biopsy specimens taken from the region perfused by the anomalous artery showed a variable degree of fibrosis (51 +/- 32%). The ultrastructure of the remaining myocytes revealed viable characteristics, but a substantial percent (46 +/- 26%) showed a markedly reduced fraction of contractile material. CONCLUSIONS: These ultrastructural studies suggest delayed subcellular adaptive responses in the chronically hypoperfused myocardium of patients with ALCAPA syndrome.

Adolescent↗
PubMed1994

Combined valve and coronary artery bypass surgery: early and late results.

Determinants of early, late and event-free survival of combined valve and coronary artery bypass graft (CABG) surgery were studied in 420 patients using multivariate analysis. It was found that the risk of hospital death increases 5 times when the preoperative NYHA class was > or = IV, 3 times when left ventricular (LV) function is significantly impaired and is double when mitral regurgitation is present. The survival probability of hospital survivors was 91% (87.3-94.5%) at 5 years. Late mortality was determined by advanced preoperative NYHA class ( > or = IV) and the presence of mitral regurgitation. The event-free survival probability of hospital survivors, i.e. total events including death, valve-related complications, ischemic complications and recurrent NYHA class > or = IV, was 73.0% (66.7-79.5%) at 5 years. Postoperative events were determined by the presence of preoperative NYHA class > or = IV, impaired ventricular function, mitral regurgitation and non-sinus rhythm. It is concluded that these parameters can be considered as the most important predictors of clinical outcome after combined valve and CABG surgery.

Adult↗
PubMed1994

Platypnoea syndrome caused by atrial septal aneurysm.

A patient with platypnoea after right pneumonectomy and radiotherapy is described. On transoesophageal contrast echocardiography and cardiac catheterization, an atrial septal aneurysm with interatrial right-to-left shunting was detected. Symptoms disappeared after surgical correction. To the best of our knowledge, this is the first report of a patient with a septal aneurysm and severe platypnoea.

Aged↗