Publications
Below you can find a list of our published research.
Below you can find a list of our published research.
94 results
Cited 37 times since 2000 (1.6 per year) source: EuropePMC
Journal of cardiovascular electrophysiology, Volume 11, Issue 11, 1 1 2000, Pages 1183-1192 Three-dimensional catheter positioning during radiofrequency ablation in patients: first application of a real-time position management system. de Groot NM, Bootsma M, van der Velde ET, Schalij MJ
Introduction: Precise localization of target sites for radiofrequency catheter ablation (RFCA) of arrhythmias is hampered by the relative inaccuracy of X-ray localization procedures. This study evaluated the efficacy of a three-dimensional (3D) real-time position management system in guiding RFCA procedures in patients. Methods and results: Patients (n = 30, age 59+/-20 years) referred for ablation of either atrial flutter (n = 10), ventricular tachycardia (n = 15), or accessory pathways (n = 5)... Abstract
Cited 11 times since 2000 (0.5 per year) source: EuropePMC
Critical care medicine, Volume 28, Issue 5, 1 1 2000, Pages 1599-1606 Evaluation of a new transcardiac conductance method for continuous on-line measurement of left ventricular volume. Steendijk P, Lardenoye JW, van der Velde ET, Schalij MJ, Baan J
Objective: To evaluate a new, less invasive, conductance method to measure continuous on-line left ventricular volume. End-systolic and end-diastolic volumes obtained with this transcardiac conductance method were compared with simultaneous measurements using the conventional intracardiac conductance catheter. Design: Controlled animal study. Setting: Research laboratory in a university hospital. Subjects: Six sheep. Interventions: Anesthetized sheep were instrumented and inotropic condition was... Abstract
Cited 3 times since 2000 (0.1 per year) source: EuropePMC
Medicine and science in sports and exercise, Volume 32, Issue 3, 1 1 2000, Pages 571-575 Correlated neurocardiologic and fitness changes in athletes interrupting training. Frederiks J, Swenne CA, Bruschke AV, van der Velde ET, Maan AC, TenVoorde BJ, Vanrooijen MG, Mosterd WL, Schiereck P
Purpose: We studied nine male Dutch top marathon skaters during a 1-month interruption of their training schedules after their last contest in the winter to investigate a possible decline in baroreflex sensitivity. Methods: Before and after this period, a maximal exercise test was done, and at days 0, 4, 7, 14, and 28 neurocardiologic measurement sessions--heart rate and noninvasive baroreflex sensitivity, recumbent and tilt--were performed. Results: Interruption of training resulted in a signif... Abstract
Cited 6 times since 1999 (0.2 per year) source: EuropePMC
Basic research in cardiology, Volume 94, Issue 1, 1 1 1999, Pages 23-30 Pretreatment with allopurinol in cardiac hypoxic-ischemic reperfusion injury in newborn lambs exerts its beneficial effect through afterload reduction. Shadid M, Van Bel F, Steendijk P, Dorrepaal CA, Moison R, Van der Velde ET, Baan J
The aim of this study was to determine whether allopurinol (ALLO) reduces reperfusion injury inflicted upon the heart resulting from excess production of free oxygen radicals after hypoxia and ischemia (HI) in newborn animals. We, therefore, produced severe HI in 13 newborn lambs by low O2-ventilation and blood volume reduction. One hour before HI seven lambs received ALLO (20 mg/kg i.v.), six received a placebo (CONT). Cardiac function and hemodynamic parameters were assessed by sequential meas... Abstract
Cited 5 times since 1999 (0.2 per year) source: EuropePMC
Biology of the neonate, Volume 75, Issue 4, 1 1 1999, Pages 239-249 Effect of deferoxamine on post-hypoxic-ischemic reperfusion injury of the newborn lamb heart. Shadid M, Van Bel F, Steendijk P, Dorrepaal CA, Moison R, Van Der Velde ET, Baan J
Unlabelled: Post-hypoxic-ischemic (HI) reperfusion induces excess production of non-protein-bound iron (NPBI), leading to formation of the highly reactive hydroxyl radical. We investigated whether the iron-chelator deferoxamine (DFO) could reduce reperfusion injury and improve left ventricular (LV) function. We produced severe HI in 14 newborn lambs and measured pre-HI, upon reperfusion, 60 and 120 min after HI the following parameters: mean aortic blood pressure, total peripheral resistance, st... Abstract
Cited 30 times since 1998 (1.2 per year) source: EuropePMC
Circulation, Volume 98, Issue 20, 1 1 1998, Pages 2168-2179 Endocardial activation mapping of ventricular tachycardia in patients : first application of a 32-site bipolar mapping electrode catheter. Schalij MJ, van Rugge FP, Siezenga M, van der Velde ET
Background: Localization of early activated endocardial areas during ventricular tachycardia (VT) is mandatory for performance of surgical or radiofrequency catheter interventions. The use of a multielectrode catheter may shorten the procedure time and increase the accuracy of the procedure compared with single-electrode mapping techniques. This study was performed to evaluate the safety and efficacy of a 32-bipolar-electrode mapping catheter in patients. Methods and results: The basket-shaped m... Abstract
Cited 38 times since 1998 (1.5 per year) source: EuropePMC
Journal of the American College of Cardiology, Volume 32, Issue 3, 1 1 1998, Pages 816-826 Effects of critical coronary stenosis on global systolic left ventricular function quantified by pressure-volume relations during dobutamine stress in the canine heart. Steendijk P, Baan J, Van der Velde ET, Baan J
Objectives: In this study we quantified the effects of a critical coronary stenosis on global systolic function using pressure-volume relations at baseline and during incremental dobutamine stress. Background: The effects of coronary stenosis have previously been analyzed mainly in terms of regional (dys)function. Global hemodynamics are generally considered normal until coronary flow is substantially reduced. However, pressure-volume analysis might reveal mechanisms not fully exposed by potenti... Abstract
Cited 37 times since 1997 (1.4 per year) source: EuropePMC
Circulation, Volume 96, Issue 9, 1 1 1997, Pages 2978-2986 Left ventricular pressure-volume relationships before and after cardiomyoplasty in patients with heart failure. Schreuder JJ, van der Veen FH, van der Velde ET, Delahaye F, Alfieri O, Jegaden O, Lorusso R, Jansen JR, Hoeksel SA, Finet G, Volterrani M, Kaulbach HG, Baan J, Wellens HJ
Background: The aim of this study was to elucidate whether beneficial effects of cardiomyoplasty (CMP) in patients with dilated cardiomyopathy are the result of a decrease in existing ventricular dilatation or a prevention of further dilatation. Methods and results: Combined micromanometer-conductance catheters were used to evaluate left ventricular pressure-volume relationships in six patients with dilated cardiomyopathy before and at 6 and 12 months after CMP. Acute changes in preload and afte... Abstract
Biology of the neonate, Volume 72, Issue 4, 1 1 1997, Pages 227-234 Nitric oxide inhibition after hypoxia-ischemia elevates pulmonary arterial pressure and increases oxygen need. de Beaufort AJ, Lopes Cardozo RH, Dorrepaal CA, Steendijk P, Van Der Velde ET, Van Bel F
Inhibition of nitric oxide (NO) production may reduce post-hypoxic-ischemic (HI) neonatal brain damage, but may also induce pulmonary hypertension by inhibiting endogenous NO production in the pulmonary vascular bed. The aim of this study was to evaluate the effect of nitric oxide inhibition on pulmonary artery pressure and oxygen need after hypoxic ischemia. Severe HI was produced in 18 newborn lambs. After completion of HI the lambs were divided into three groups of 6 animals receiving either... Abstract
Cited 14 times since 1997 (0.5 per year) source: EuropePMC
Biology of the neonate, Volume 72, Issue 4, 1 1 1997, Pages 216-226 Effect of post-hypoxic-ischemic inhibition of nitric oxide synthesis on cerebral blood flow, metabolism and electrocortical brain activity in newborn lambs. Dorrepaal CA, Shadid M, Steendijk P, Van der Velde ET, Van de Bor M, Baan J, Van Bel F
Since an excessive production of nitric oxide upon reperfusion/reoxygenation may play an important role in post-hypoxic-ischemic (HI) brain injury, we investigated whether immediate post-HI blockade of nitric oxide synthesis by N-omega-nitro-L-arginine (NLA) may reduce this injury. In 18 newborn lambs, subjected to severe HI, changes from pre-HI values were measured for carotid blood flow (Qcar [ml/min]) as a measure of changes in brain blood flow, (relative) cerebral metabolic rate of oxygen (C... Abstract
Cited 6 times since 1995 (0.2 per year) source: EuropePMC
European heart journal, Volume 16, Issue 12, 1 1 1995, Pages 1860-1871 Comparison between regional myocardial perfusion reserve and coronary flow reserve in the canine heart. Geldof MJ, Schalij MJ, Manger Cats V, van der Zwet PM, Steendijk P, van der Velde ET, Nagtegaal EM, Reiber JH, Bruschke AV
Diameter stenosis and flow reserve are indices of morphological and functional severity of coronary artery stenosis. Flow reserve can be determined at coronary arterial or at myocardial level. In the presence of functional collateral circulation, coronary flow reserve and myocardial perfusion reserve may differ. We studied coronary flow, coronary flow reserve and myocardial perfusion reserve in an open chest dog model with intact collateral circulation, before and after induction of coronary art... Abstract
Cited 10 times since 1995 (0.4 per year) source: EuropePMC
Magnetic resonance in medicine, Volume 34, Issue 5, 1 1 1995, Pages 728-737 Magnetic resonance imaging analysis of left ventricular pressure-volume relations: validation with the conductance method at rest and during dobutamine stress. Pattynama PM, de Roos A, Van der Velde ET, Lamb HJ, Steendijk P, Hermans J, Baan J
The accuracy of magnetic resonance (MR) imaging was assessed for in vivo measurement of the ventricular end-systolic pressure-volume relation (ESPVR) and preload recruitable stroke work (PRSW). The conductance catheter was used as reference. In 10 pigs, ventricular volumes were measured with both methods under different loading conditions at two levels of contractility. Increased contractility resulted in a significant leftward shift of the ESPVR and PRSW for both methods. The magnitude of these... Abstract
Cited 51 times since 1995 (1.8 per year) source: EuropePMC
Circulation, Volume 91, Issue 7, 1 1 1995, Pages 2010-2017 Beat-to-beat analysis of left ventricular pressure-volume relation and stroke volume by conductance catheter and aortic Modelflow in cardiomyoplasty patients. Schreuder JJ, van der Veen FH, van der Velde ET, Delahaye F, Alfieri O, Jegaden O, Lorusso R, Jansen JR, van Ommen V, Finet G
Background: Since the clinical introduction of dynamic cardiomyoplasty, a discrepancy has been observed between unchanged measurements of cardiac function and improved clinical outcome. Methods and results: We performed a beat-to-beat analysis of cardiac performance at rest in nine cardiomyoplasty patients 6 to 24 months after operation. Conductance and micromanometer catheters were placed in left ventricle and aorta and used for measurements over a 15-second period, during which the wrapped lat... Abstract
Cited 2 times since 1994 (0.1 per year) source: EuropePMC
The American journal of physiology, Volume 267, Issue 5 Pt 2, 1 1 1994, Pages H1895-906 Determinants of end-systolic pressure during different load alterations in the in situ left ventricle. van der Linden LP, van der Velde ET, van Houwelingen HC, Bruschke AV, Baan J
Because of the strong dependency of the end-systolic pressure-volume relation on the type of transient loading intervention in the in situ left ventricle (LV), experiments in the basal inotropic state in 16 open-chest anesthetized dogs were reanalyzed to find additional variables to model and predict end-systolic pressure (ESP) of both afterloading and preloading interventions by a single equation. Random-coefficients regression analysis was performed on 22 experiments in the basal inotropic sta... Abstract
Cited 31 times since 1994 (1 per year) source: EuropePMC
Basic research in cardiology, Volume 89, Issue 5, 1 1 1994, Pages 411-426 Dependence of anisotropic myocardial electrical resistivity on cardiac phase and excitation frequency. Steendijk P, van der Velde ET, Baan J
Knowledge of myocardial electrical resistivity is of interest because passive electrical properties govern the electrotonic spread of current through the myocardium and influence the shape and velocity of the excitation wave. In addition, measurements of myocardial resistivity may provide information about tissue structure and components. The aim of the present study was to determine the excitation frequency dependence and the changes during the cardiac cycle of anisotropic myocardial electrical... Abstract
Cited 5 times since 1994 (0.2 per year) source: EuropePMC
Magnetic resonance imaging, Volume 12, Issue 3, 1 1 1994, Pages 531-534 Cardiovascular MR imaging: pressure-gating using the arterial pressure signal from a conventional ferromagnetic micromanometer-tip catheter. Pattynama PM, van der Velde ET, Steendijk P, Lamb HJ, Baan J, de Roos A
We used the arterial pressure wave as a reliable trigger to synchronize MR imaging to the cardiac cycle. Pressure readings and MR images remained undistorted using a conventional ferromagnetic micromanometer-tip catheter. As a safe alternative to triggering to ventricular pressure, this approach allows varying the time relation between the trigger and the cardiac cycle while maintaining the advantages of pressure-gating. Abstract
Cited 1 times since 1994 (0 per year) source: EuropePMC
European heart journal, Volume 15, Issue 1, 1 1 1994, Pages 83-88 Acute effects of balloon valvuloplasty and pacing on left ventricular performance in children with moderate pulmonary valve stenosis, analysed by systolic and diastolic pressure-volume relationships. Witsenburg M, van der Velde ET, Klautz RJ, Hess J, Baan J
Right ventricular overload of volume and/or pressure type may affect left ventricular systolic and diastolic function. This has been shown in animal studies and has been suggested in non-invasive studies in man. Altered geometry of the left ventricle, myocardial hypertrophy and changes in contractile state may be responsible for the change in function. Balloon valvuloplasty is an effective treatment for isolated valvular pulmonary stenosis in children, and results in an immediate decrease of rig... Abstract
Cited 8 times since 1993 (0.3 per year) source: EuropePMC
Pflugers Archiv : European journal of physiology, Volume 425, Issue 5-6, 1 1 1993, Pages 426-433 Cardiac sympathetic denervation does not change the load dependence of the left ventricular end-systolic pressure/volume relationship in dogs. Schipper IB, Steendijk P, Klautz RJ, van der Velde ET, Baan J
It has been shown that in the intact canine heart the left-ventricular end-systolic pressure/volume relation (ESPVR) depends on loading conditions: an increase in arterial vascular resistance causes a leftwards shift and a steeper slope of the ESPVR, suggesting an increased inotropic state. Our purpose was to investigate the possible contribution of the sympathetic nervous system to this load sensitivity of the ESPVR, using intact, but denervated, hearts with normal coronary perfusion and afterl... Abstract
Cited 57 times since 1993 (1.9 per year) source: EuropePMC
IEEE transactions on bio-medical engineering, Volume 40, Issue 11, 1 1 1993, Pages 1138-1148 The four-electrode resistivity technique in anisotropic media: theoretical analysis and application on myocardial tissue in vivo. Steendijk P, Mur G, Van Der Velde ET, Baan J
Several aspects of the four-electrode resistivity technique were studied with special emphasis on the theoretical determination of penetration depth and sample volume in anisotropic media such as (cardiac) muscle. Moreover, the presence of a thin disturbing layer on top of the medium under study was analyzed. A four-electrode sensor was developed for the measurement of local myocardial resistivity in two orthogonal directions. The sensor was applied to the epicardium of anesthetized open chest d... Abstract
Cited 50 times since 1993 (1.6 per year) source: EuropePMC
The American journal of physiology, Volume 264, Issue 6 Pt 2, 1 1 1993, Pages H2198-207 Left ventricular stroke volume by single and dual excitation of conductance catheter in dogs. Steendijk P, Van der Velde ET, Baan J
The conductance method employs a multielectrode catheter to measure intracavitary electric conductance from which left ventricular volume is estimated. A dual-excitation method introduced by us uses a more homogeneous electric field and thereby should enable more accurate volume estimation. In six anesthetized open-chest dogs we compared stroke volume obtained from electromagnetic flow probes with the conventional single-excitation method and with the new dual-excitation conductance method. Cava... Abstract