Publications
Below you can find a list of our published research.
Below you can find a list of our published research.
251 results
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 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 12 times since 1998 (0.5 per year) source: EuropePMC
Journal of computer assisted tomography, Volume 22, Issue 4, 1 1 1998, Pages 569-576 Differential response of the right and left ventricle to beta-adrenergic stimulation: an echo planar MR study in intact animals. Jerzewski A, Pattynama PM, Steendijk P, Leeuwenburgh BP, de Roos A, Baan J
Purpose: The purpose of this study was to compare the response in contractility of the right (RV) and left (LV) ventricle of the heart to beta-adrenergic stimulation using an echo planar MR technique. Method: In six sheep, RV and LV pressure-volume (P-V) relationships were constructed simultaneously using intraventricular pressures and volumes measured with echo planar MRI at rest and during dobutamine stress. Contractility changes were quantified by assessment of the end-systolic P-V relationsh... Abstract
Cited 25 times since 1998 (1 per year) source: EuropePMC
Pediatric research, Volume 44, Issue 1, 1 1 1998, Pages 119-124 The effect of antioxidative combination therapy on post hypoxic-ischemic perfusion, metabolism, and electrical activity of the newborn brain. Shadid M, Moison R, Steendijk P, Hiltermann L, Berger HM, van Bel F
Reoxygenation and reperfusion after severe hypoxia and ischemia (HI) contribute substantially to birth asphyxia-related brain injury. Excess production of free radicals via metabolization of arachidonic acid, xanthine oxidase, and non-protein-bound iron play an important role. Cerebral reperfusion injury is characterized by a decrease in perfusion, oxygen consumption, and electrical activity of the brain. Reduction of free radical production may attenuate these features. We therefore induced sev... Abstract
Cited 6 times since 1997 (0.2 per year) source: EuropePMC
The Journal of thoracic and cardiovascular surgery, Volume 114, Issue 4, 1 1 1997, Pages 560-567 Acute elevation of coronary venous pressure does not affect left ventricular contractility in the normal and stressed swine heart: implications for the Fontan operation. Klautz RJ, van Rijk-Zwikker GL, Steendijk P, Wilde J, Teitel DF, Baan J
Objective: After the Fontan operation the right atrium and, thus, the coronary sinus are connected to the pulmonary arterial system, which causes the coronary venous pressure to increase. We investigated the acute effects of elevation of coronary venous pressure on baseline hemodynamics, coronary venous flow, and left ventricular contractility. Methods: In acutely instrumented pigs, during complete right heart bypass and during constant cardiac output, pressure in the right atrium, right ventric... Abstract
Cited 15 times since 1997 (0.6 per year) source: EuropePMC
Pediatric research, Volume 41, Issue 3, 1 1 1997, Pages 321-326 Oxidative stress during post-hypoxic-ischemic reperfusion in the newborn lamb: the effect of nitric oxide synthesis inhibition. Dorrepaal CA, van Bel F, Moison RM, Shadid M, van de Bor M, Steendijk P, Berger HM
Post-hypoxic-ischemic (HI) reperfusion induces endothelium and neurons to produce excessive amounts of nitric oxide and superoxide, leading to peroxynitrite formation, release of protein-bound metal ions (i.e. iron), and cytotoxic oxidants. We produced severe HI in 18 newborn lambs and serially determined plasma prooxidants (non-protein-bound iron), lipid peroxidation (malondialdehyde), and antioxidative capacity [ratio of ascorbic acid/dehydroascorbic acid (AA/DHA), alpha-tocopherol, sulfhydryl... 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 4 times since 1996 (0.1 per year) source: EuropePMC
Basic research in cardiology, Volume 91, Issue 6, 1 1 1996, Pages 468-478 Systolic coronary flow reduction in the canine heart in situ: effects of left ventricular pressure and elastance. Baan J, Steendijk P, Mikuniya A, Baan J
In the externally perfused coronary bed of the isolated heart, LV elastance (Elv) rather than LV pressure (Plv) appears to be the major factor responsible for systolic coronary flow reduction, although effects of both have been demonstrated. However, normal perfusion in the presence of intact autoregulation in the heart in situ may modify these effects. To investigate the systolic coronary flow (Qsyst) responses to changes in end-systolic Elv and in systolic Plv in the intact coronary bed, we st... Abstract
Cited 6 times since 1996 (0.2 per year) source: EuropePMC
Journal of magnetic resonance imaging : JMRI, Volume 6, Issue 6, 1 1 1996, Pages 948-949 Development of an MRI-compatible catheter for pacing the heart: initial in vitro and in vivo results. Jerzewski A, Pattynama PM, Steendijk P, Doornbos J, de Roos A, Baan J
An MRI-compatible catheter was developed for pacing the heart during MRI imaging. The device was tested in vitro and in vivo in 10 animal experiments, using spin-echo, gradient-echo, and echo-planar MRI sequences. Images were of good quality in all sequences. Pacing was effective without induced arrhythmias. Therefore, pacing the heart during MRI is feasible and seems to be safe when using dedicated hardware. 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 19 times since 1995 (0.7 per year) source: EuropePMC
Journal of the American College of Cardiology, Volume 25, Issue 6, 1 1 1995, Pages 1428-1435 Interaction between afterload and contractility in the newborn heart: evidence of homeometric autoregulation in the intact circulation. Klautz RJ, Teitel DF, Steendijk P, van Bel F, Baan J
Objectives: We undertook the present study to determine whether afterload and contractility interact in the hearts of newborn lambs. We specifically investigated whether stepwise increases in afterload increase contractility. Background: Several studies in the isolated and intact adult dog heart have shown that afterload and contractility are not independent determinants of cardiac performance; rather, they interact. Afterload and contractility are unlikely to interact in the newborn heart becau... 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 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 18 times since 1993 (0.6 per year) source: EuropePMC
Pediatric research, Volume 34, Issue 2, 1 1 1993, Pages 178-181 The influence of indomethacin on the autoregulatory ability of the cerebral vascular bed in the newborn lamb. van Bel F, Klautz RJ, Steendijk P, Schipper IB, Teitel DF, Baan J
Prevention of hyperperfusion of the brain in the perinatal period has been thought to be an important mechanism by which indomethacin reduces the risk for severe periventricular-intraventricular hemorrhage. The present study investigated whether an indomethacin-induced enhancement of the upper limit of cerebral vascular autoregulatory ability in the neonate contributed to this reduction in cerebral blood flow. In seven anesthetized newborn lambs, we measured temporal blood flow velocity (TMFV) i... 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
Cited 7 times since 1993 (0.2 per year) source: EuropePMC
Basic research in cardiology, Volume 88, Issue 2, 1 1 1993, Pages 167-178 Effect of coronary occlusion and reperfusion on local electrical resistivity of myocardium in dogs. Steendijk P, van Dijk AD, Mur G, van der Velde ET, Baan J
The effect of coronary occlusion and reperfusion on myocardial electrical resistivity was studied in nine anesthetized open-chest dogs. Anisotropic resistivity was measured on the anterior free wall of the left ventricle (LV) before (control) and during transient occlusion of the left anterior descending (LAD) coronary artery, and during reperfusion. To measure local resistivity longitudinal (RL) and transverse (RT) to epicardial muscle fiber direction, a sensor was developed based on the four e... Abstract