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Biomedical subjects

D De Wolf

Publications and source records attributed to D De Wolf.

At least 19 recordsLinked to original sources
PubMed1999

The influence of low afterload on the nature of the stress-velocity relationship.

OBJECTIVES: Correct assessment of contractility by conventional methods during manipulation of afterload is often disappointing. To this purpose, the stress-velocity relationship offers assessment of contractility at different levels of afterload. We decided to study the influence of afterload on the nature of the stress-velocity relation. BACKGROUND: Although linear at baseline conditions in a population older than two years, data in newborns or after administration of low-dose dobutamine suggest a different nature of this relationship at low afterload. METHODS: Ten healthy piglets (five to six weeks; 11 to 13 kg) were studied. End-systolic meridional wall stress (ESWS) and rate-corrected velocity of circumferential fiber shortening (VcFc) were measured in these piglets at baseline, after balloon occlusion of the descending aorta, and at nitroprusside infusion rates of 1, 2 and 5 microg/kg/min. To eliminate inotropic influences mediated by reflex tachycardia, we subsequently studied five piglets and six adult pigs after bilateral cervical vagotomy. RESULTS: The ESWS changed from a baseline mean of 50 g/cm2 to 137 g/cm2 after balloon occlusion and to 19 g/cm2 at 5 microg/kg/min of nitroprusside. The VcFc changed from 1.19 c/s (circumference/second) to values of 0.9 c/s and 1.73 c/s, respectively. The ensuing stress-velocity regression line proved to be curvilinear instead of linear. The steeper slope at low afterload could suggest enhanced contractility compared to expected values had the relationship been linear. CONCLUSIONS: Data from young piglets and adult pigs suggest a curvilinear relationship of the stress-velocity relationship. This could probably explain some of the "hypercontractile states" encountered in conditions with low afterload.

Age Factors↗
PubMed1999

In vivo evaluation of a phosphorylcholine coated cardiopulmonary bypass circuit.

A complete phosphorylcholine coated cardiopulmonary bypass circuit, including the Dideco D901 oxygenator, was tested for gas transfer, blood path resistance, and biocompatibility in a standardized setting. Blood compatibility was tested by measuring complement and platelet activation. Three dogs (mean body weight 28 +/- 3 kg) were placed on cardiopulmonary bypass at a flow rate of 600 mL/min during 6 hours. The animals were weaned from cardiopulmonary bypass and sacrificed electively after 7 days. Oxygen and carbon dioxide transfer were 26.6 +/- 2.4 mL/min and 33.0 +/- 1.9 mL/min, respectively. Mean pressure drop across the oxygenator was 52.6 +/- 0.2 mmHg. The respective baseline values for thromboxane B2, prostaglandin E2 and platelet factor 4 were 1817 +/- 283 pg/mL, 12783 +/- 2109 pg/mL, and 0.35 +/- 0.08 IU/mL. Thromboxane B2 and prostaglandin E2 increased slightly to 2881 +/- 868 pg/mL and 18083 +/- 3144 pg/mL at 30 minutes of bypass, whereas platelet factor 4 values remained stable curing the procedure. Concentrations of complement split products C5a were only mildly increased. After use scanning electron microscopy was performed on the inner housing, heat exchanger, and outer surface of the hollow fibers. No thrombi nor organized cellular deposits were found on any of the components. Phosphorylcholine coating of CPB seems to be very promising regarding platelet activation and complement activation.

Animals↗
PubMed1998

Low-dose dobutamine stress echocardiography in children and young adults.

Dobutamine stress echocardiography has become widely accepted in the evaluation of adult patients with coronary heart disease. We wanted to assess the feasibility and the physiologic responses of stress echocardiography at low doses of dobutamine in a population of normal children and adults. Once achieved, we submitted a group of post-anthracycline patients to the test to assess the sensitivity of low-dose dobutamine stress echocardiography in the detection of cardiac dysfunction. Thirty-two healthy children and young adults (19 male and 13 female subjects, median age 15 years [range 6 to 26]) were studied. After the initial study of normal subjects, we submitted a cohort of 39 patients (18 female and 21 male, aged 6 to 25 years), who completed anthracycline chemotherapy, to the same protocol. Dobutamine was infused at rates of 0.5 to 2.5 and 5 microg/kg/min and echocardiographic measurements were obtained at rest and at the end of each stage. The test could be completed in 100% of the subjects without major complications. Statistically significant differences between resting echocardiographic values of systolic and diastolic function and values at 2.5 and 5 microg/kg/min of dobutamine were found. Moreover, dobutamine revealed or enhanced differences between normal subjects and the post-anthracycline patients. Thus, low-dose dobutamine stress echocardiography is feasible and safe in older children. The test is very sensitive for the detection of subclinical cardiac dysfunction in post-anthracycline patients and could possibly assess functional myocardial reserve.

Adolescent↗
PubMed1998

Left ventricular perfusion deficit in patients with cystic fibrosis.

Left ventricular failure is not considered an important feature in cystic fibrosis (CF), but abnormalities of left ventricular function have been reported. Except for a few cases of heart failure in neonates with CF, there is no evidence of a primary disorder of the myocardium in patients with CF. Since left ventricular perfusion disturbances can cause left ventricular dysfunction, we decided to investigate left ventricular perfusion during exercise using sestamibi-Tc-99m-labeled macroaggregates. Eighteen CF patients with varying degrees of disease severity participated in the study. They underwent a thorough clinical evaluation, lung perfusion scan, pulmonary function testing, echocardiography, transcutaneous measurement of oxygen saturation at rest and during exercise, and an exercise test with injection of sestamibi-Tc-99m-labeled macroaggregates at peak exercise. Six patients (33%) showed abnormalities of the myocardial distribution of sestamibi-Tc-99m-labeled macroaggregates during exercise. Scanning abnormalities correlated with the clinical score, mean maximum expiratory flow at 50% of vital capacity (MEF50), and arterial oxygen desaturation during exercise. We conclude that deficits in left ventricular uptake of sestamibi-Tc-99m-labeled macroaggregates during exercise seem common in patients with severe CF lung disease. The cause of these deficits is not fully understood, but the occurrence seems to be associated with a poor prognosis.

Adult↗
PubMed1998

Influence of age and low afterload on the stress-velocity relation of the left ventricle.

The relation between systolic meridional wall stress (WS) and velocity of circumferential fiber shortening (VcFc) is widely accepted as a preload-independent index of contractility, with a linear relation in most subjects older than 2 y. However, this relation seems to become different in infants and after administration of inotropic agents. We decided to study the nature of the stress-velocity relation by a cross-sectional assessment of the influence of age, low afterload, and increased contractility. Study subjects were 30 healthy infants, 32 healthy older children, and 35 asymptomatic older children after completion of anthracycline chemotherapy. WS and VcFc at rest were studied in these infants and children. WS and VcFc were also studied after dobutamine infusion in both groups of older children. Linear regression analysis of the stress-velocity relation showed parallel slopes between the older children at rest and the post anthracycline children after dobutamine. The regression lines between the infants at rest and the healthy older children after dobutamine were also parallel, but with a different and steeper slope compared with the former groups. When comparing the stress-velocity relation of the overall population at rest with the overall population after dobutamine, the resulting regression lines are curvilinear and parallel, with a steeper slope at low afterload. The stress-velocity relation in infants and after dobutamine, resulting in low afterload is different compared with the stress- velocity relation in older children at rest and at higher afterload. Data of the overall population at rest and after dobutamine suggest a curvilinear relation.

Adult↗
PubMed1998

Entrapment of a guide wire during percutaneous occlusion of a coronary artery fistula.

Coronary artery fistulas are extremely rare and coil occlusion by intervention techniques seems to be the therapy of choice. We describe the case of a 3-month-old infant with a coronary artery fistula. During occlusion of the fistula a coronary guide wire got entrapped in a small coronary branch, but could be successfully retrieved with a microsnare without damage to the heart. The microsnare technique prevented rupture of the guide wire.

Angioplasty, Balloon, Coronary↗
PubMed1997

Simultaneous delivery of two patent arterial duct coils via one venous sheath.

A female child, 10 months of age, weighing 7.2 kg, was catheterised for closure of a patent arterial duct. Aortography was performed in the lateral projection and the minimum diameter of the arterial duct was assessed by comparing it to the size of the catheter. The duct size was estimated between 3 and 3.5 mm at the narrowest point, therefore, it was decided to deliver two 5 mm patent arterial duct coils to avoid placement of an 8 mm coil in this small child. Similar operations were subsequently performed in two further children. Simultaneous delivery of two coils via a single long venous sheath is easy, fast, and safe. This simple and inexpensive procedure can reduce irradiation and anaesthesia time.

Ductus Arteriosus, Patent↗
PubMed1996

Dobutamine stress echocardiography in the evaluation of late anthracycline cardiotoxicity in childhood cancer survivors.

Late anthracycline cardiotoxicity has been of increasing concern to pediatric oncologists. An increasing number of patients with cardiac dysfunction has been reported without a good correlation between cardiac function or symptoms and routine echocardiographic follow-up. We studied dobutamine stress echocardiography in patients who had received moderate doses of anthracyclines years before. Twenty-three patients (14 male, 9 female; 7-25 y) who completed chemotherapy with moderate doses of anthracyclines (180-380 mg/m2) more than 2 y previously underwent dobutamine stress echocardiography and were compared with a control group of 26 healthy young people (15 male, 11 female; 6-26 y) matched for age and weight. Dobutamine was administered in three periods up to a rate of 5 micro g/kg/min. Eighty-five percent of the patients showed an abnormal response to dobutamine. Both systolic and diastolic functions were affected. The systolic dysfunction was not related to diminished contractility but to an elevated systolic wall stress due to inadequate cardiac muscle thickening. The diminished wall thickening was related to the length of follow-up. Dobutamine proved to be a very sensitive method to detect clinical and subclinical cardiac dysfunction in patients post anthracycline chemotherapy and questions the concept of a safe dose.

Adolescent↗
PubMed1996

Reduced decrease of peripheral vascular resistance during exercise in young type I diabetic patients.

OBJECTIVE: In normal subjects, peripheral vascular resistance decreases during dynamic exercise. We studied blood pressure and peripheral vascular resistance responses to dynamic exercise in young normotensive type I diabetic patients. RESEARCH DESIGN AND METHODS: Thirty adolescent diabetic patients (9-19 years of age) underwent a maximal exercise test on a cycle ergometer. In a subset of 14 patients, cardiac output was measured by a CO2 rebreathing method and peripheral vascular resistance was calculated. Twenty-four normal individuals, age and sex matched, served as control subjects. RESULTS: Diastolic blood pressure was significantly higher in diabetic patients at intermediate workload (77 +/- 2 vs. 71 +/- 1 mmHg) and peak exercise (86 +/- 2 vs. 73 +/- 2 mmHg). Peripheral vascular resistance was significantly higher in diabetic patients at intermediate workload (17.0 +/- 1.1 vs. 12.6 +/- 0.5 mmHg.l-1.min-1.m-2) and peak exercise (16.3 +/- 1.3 vs. 11.4 +/- 0.5 mmHg.l-1.min-1.m-2). There were no significant correlations with the patient's age, diabetes duration, or diabetes control. CONCLUSIONS: We observed the decrease of vasodilator response during dynamic exercise in normotensive young type I diabetic patients.

Adolescent↗
PubMed1994

Fetal hypothyroidism as a complication of amiodarone treatment for persistent fetal supraventricular tachycardia.

We present a case of persistent fetal supraventricular tachycardia where transplacental and direct fetal treatment with amiodarone caused an iatrogenic hypothyroidism. This condition was successfully managed with the intra-amniotic instillation of 250 micrograms of L-thyroxine weekly, for 3 weeks. A male infant was delivered at 32 weeks by Caesarean section. The neonatal electrocardiogram showed Wolf-Parkinson-White (WPW) syndrome, which was controlled by digoxin alone. Thyroid function normalized quickly and the baby is developing normally.

Adult↗
PubMed1994

Adenosine-tri-phosphate treatment for supraventricular tachycardia in infants.

Adenosine is an endogenous nucleoside acting on coronary perfusion and myocardial conduction. Although the anti-arrhythmic effects of adenosine have been known for decades, interest in the use of adenosine or adenosine-triphosphate (ATP) (a precursor of adenosine) in termination of supraventricular tachycardia (SVT) has been renewed. We studied the use of striadyne (ATP and a mixture of other nucleosides including adenosine) in 22 infants younger than 6 months in order to evaluate efficiency and safety of the drug in this particular age group. Striadyne stopped SVT in 17 cases and was diagnostic in another 4 cases. Ten out of 17 successfully converted infants showed one or more reinitiations of SVT, which were easily controlled. The results support the efficiency of ATP for the termination of re-entry types of tachycardia, as well as its diagnostic value and its lack of serious side-effects.

Adenosine Triphosphate↗
PubMed1994

Adenosine triphosphate treatment for supraventricular tachycardia in infants.

UNLABELLED: Adenosine is an endogenous nucleoside acting on coronary perfusion and myocardial conduction. Although the anti-arrhythmic effects of adenosine have been known for decades, interest in the use of adenosine or adenosine triphosphate (ATP- a precursor of adenosine) in termination of supraventricular tachycardia (SVT) has been renewed. We studied the use of Striadyne (ATP and a mixture of other nucleosides including adenosine) in 22 infants younger than 6 months in order to evaluate efficacy and safety of the drug in this particular age group. Striadyne stopped SVT in 17 cases and was diagnostic in another 4 cases. Ten out of 17 successfully converted infants showed one or more reinitiations of SVT, which were easily controlled. The results support the efficacy of ATP for the termination of re-entry types of tachycardia, as well as its diagnostic value and its lack of serious side-effects. CONCLUSION: Adenosine or ATP could be the drug of choice for the treatment of junctional tachycardia in infants after vagal manoeuvres have failed. Provided continuous ECG monitoring is performed during injection, adenosine or ATP may be diagnostic in other types of supraventricular tachycardia and even in wide-complex tachycardia. We suggest a bolus injection of 0.5-1.0 mg/kg to be used prior to transport to the paediatric cardiology unit.

Adenosine Triphosphate↗
PubMed1994

Bradycardia and gastroesophageal reflux in term and preterm infants: is there any relation?

Conflicting data are published regarding the influence of acid gastroesophageal reflux on the heart rate. In this study, heart rate was monitored simultaneously with esophageal pH in 50 infants with symptoms suggestive of gastroesophageal reflux disease (frequent vomiting and regurgitations). The data of 25 preterm infants (born at 28-36 6/7 weeks) were compared to those of 25 term infants (born after 37 weeks of gestation). However, both groups were investigated at identical postconceptional age of 47-49 weeks. Not one significant bradycardia (heart rate < or = 80/min during > or = 10 s) was recorded, although 71 "relative bradycardia episodes" (heart rate < or = 80/min during > or = 5 beats) were detected, none lasting for > 5 s. Although the number of infants with relative bradycardia episodes did not differ between groups, the relative bradycardia episodes occurred more frequently in some preterm infants (53 episodes in preterm infants vs. 18 in term babies). Acid gastroesophageal reflux episodes were observed in 46 infants (92%). Neither the number of reflux episodes nor their duration was different in both groups. Simultaneous relative bradycardia episodes and acid reflux episodes were observed in three of 23 preterm and two of 23 term infants (NS). It is concluded that in a population of preterm and term infants with symptoms suggestive of a moderate gastroesophageal reflux pathology, investigated at comparable postconceptional age, most reflux episodes are not time-related to changes in heart rate.

Bradycardia↗
PubMed1994

A case of term mors in utero in a chromosome 11p linked long QT syndrome family.

Isolated congenital long QT syndrome is an autosomal dominant disorder characterized by recurrent syncopes, ventricular arrhythmias, or sudden death often accompanied by a prolonged QTc interval on ECG. On the occasion of a pregnancy complicated by an intra-uterine death of a full term baby with prolonged bradycardia a long QT syndrome was diagnosed in the mother. Familial examination revealed a prolonged QTc in her mother, brother and sister, all with positive history of syncopes. DNA linkage analysis was subsequently performed in this family with DNA markers on the short arm of chromosome 11. Four of the children in the family, younger than 5 years, were found to be asymptomatic carriers. Three of them showed a clear QTc prolongation on a 12 lead ECG. Another showed QTc prolongation during Holter monitoring but had a normal basic ECG. Measurement of QTc interval in families affected by the long QT syndrome is helpful but does not always permit an accurate diagnosis. Familial screening with DNA linkage analysis especially in families where a member is affected by the syndrome, can reveal "masked" cases which can further be investigated with Holter or effort ECG. The identification of locus heterogeneity of the long QT syndrome complicates genetic diagnosis. Only prospective studies in more families with long QT syndrome can show the additional diagnostic and prognostic value of DNA linkage.

Adult↗
PubMed1994

Right ventricular hypoplasia: outcome after conservative perinatal management.

Isolated right ventricular hypoplasia is a rare congenital cardiac anomaly. A case described in which prenatal diagnosis was made by echocardiography. Conservative perinatal management produced a favourable short-term outcome without compromising the definitive surgical intervention later. The decisions were based on principles used in the treatment of pulmonary atresia with intact interventricular septum.

Cardiac Catheterization↗
PubMed1994

Ectopic atrial tachycardia in a young athlete.

We report the case of a young boy on routine sports medical examination, who presented an incessant atrial tachycardia. At the slightest exercise the ventricular rhythm accelerated to 160 beats.min-1. Exercise capacity was excellent, and a treatment with propafenone suppressed the tachyarrhythmia.

Child↗