76 results on '"Kroon W"'
Search Results
2. A pulse wave propagation model to support decision-making in vascular access planning in the clinic
- Author
-
Huberts, W., Bode, A.S., Kroon, W., Planken, R.N., Tordoir, J.H.M., van de Vosse, F.N., and Bosboom, E.M.H.
- Published
- 2012
- Full Text
- View/download PDF
3. Asymptotic Statistics: Moment Estimators and M-estimators in Parametric Models
- Author
-
Kroon, W. and Kroon, W.
- Published
- 2020
4. PREDICTING INITIAL POSTOPERATIVE FLOW AFTER AVF CREATION FOR HEMODIALYSIS: FEASIBILITY OF PATIENTSPECIFIC MODELING
- Author
-
Huberts, W., Bosboom, E. M.H., Planken, R. N., Kroon, W., Tordoir, J. H.M., and van de Vosse, F. N.
- Published
- 2009
5. Validation of a patient-specific hemodynamic computational model for surgical planning of vascular access in hemodialysis patients
- Author
-
Caroli, Anna, Manini, Simone, Antiga, Luca, Passera, Katia, Ene-Iordache, Bogdan, Rota, Stefano, Remuzzi, Giuseppe, Bode, Aron, Leermakers, Jaap, Van De Vosse, Frans N., Vanholder, Raymond, Malovrh, Marko, Tordoir, Jan, Remuzzi, Andrea, Tordoir, J. H.M., Bode, A. S., Dacco, Aldo E.Cele, Antiga, L., Manini, S., Passera, K., Botti, L., Hameeteman, M., Leermakers, J. J.P.M., Planken, R. N., Leiner, T., Huberts, W., Merkx, M., Kroon, W., Bosboom, E. M.H., Van De Vosse, F. N., Van Canneyt, K., Araujo, L., Verdonck, P., Segers, P., Malovrh, M., Narracott, A., Bayley, M., Breeuwer, M., Olivan-Bescos, J., Van Der linden, W., Alves De Inda, M., Brands, P., Radiology and Nuclear Medicine, ACS - Amsterdam Cardiovascular Sciences, MUMC+: MA AIOS Heelkunde (9), Biomedische Technologie, Surgery, RS: CARIM School for Cardiovascular Diseases, and Cardiovascular Biomechanics
- Subjects
Male ,Time Factors ,Fistula ,medicine.medical_treatment ,030232 urology & nephrology ,Hemodynamics ,030204 cardiovascular system & hematology ,Surgical planning ,0302 clinical medicine ,access blood flow ,hemodialysis access ,vascular access ,Medicine ,Longitudinal Studies ,Prospective Studies ,Brachial artery ,Aged, 80 and over ,Graft Occlusion, Vascular ,Models, Cardiovascular ,Settore ING-IND/34 - Bioingegneria Industriale ,Middle Aged ,3. Good health ,Europe ,Treatment Outcome ,Surgery, Computer-Assisted ,Nephrology ,Settore ING-IND/06 - Fluidodinamica ,Female ,Hemodialysis ,Blood Flow Velocity ,Adult ,medicine.medical_specialty ,Arteriovenous fistula ,Decision Support Techniques ,Upper Extremity ,Young Adult ,03 medical and health sciences ,Arteriovenous Shunt, Surgical ,Renal Dialysis ,medicine.artery ,Humans ,Vascular Patency ,Computer Simulation ,Aged ,business.industry ,Patient Selection ,Reproducibility of Results ,Blood flow ,medicine.disease ,Surgery ,Regional Blood Flow ,business - Abstract
Vascular access dysfunction is one of the main causes of morbidity and hospitalization in hemodialysis patients. This major clinical problem points out the need for prediction of hemodynamic changes induced by vascular access surgery. Here we reviewed the potential of a patient-specific computational vascular network model that includes vessel wall remodeling to predict blood flow change within 6 weeks after surgery for different arteriovenous fistula configurations. For model validation, we performed a multicenter, prospective clinical study to collect longitudinal data on arm vasculature before and after surgery. Sixty-three patients with newly created arteriovenous fistula were included in the validation data set and divided into four groups based on fistula configuration. Predicted brachial artery blood flow volumes 40 days after surgery had a significantly high correlation with measured values. Deviation of predicted from measured brachial artery blood flow averaged 3% with a root mean squared error of 19.5%, showing that the computational tool reliably predicted patient-specific blood flow increase resulting from vascular access surgery and subsequent vascular adaptation. This innovative approach may help the surgeon to plan the most appropriate fistula configuration to optimize access blood flow for hemodialysis, potentially reducing the incidence of vascular access dysfunctions and the need of patient hospitalization.
- Published
- 2013
6. P3.07 Quantitative Method to Determine Smooth Muscle Cell Orientation in Vital Arteries
- Author
-
Spronck, B., Merken, J. J., Kroon, W., Megens, R. T. A., Reesink, K. D., and Delhaas, T.
- Published
- 2012
- Full Text
- View/download PDF
7. How to choose myofiber orientation in a biventricular finite element model?
- Author
-
Pluijmert, Marieke, Prinzen, Frits, Flores de la Parra, A.F., Kroon, W., Delhaas, Tammo, Bovendeerd, P.H., van Assen, H., Bovendeerd, P., Delhaas, T., Biomedische Technologie, Fysiologie, RS: CARIM - R2 - Cardiac function and failure, and Cardiovascular Biomechanics
- Subjects
Stroke work ,Computer science ,business.industry ,Orientation (computer vision) ,Myocyte ,Geometry ,business ,Finite element method ,Electromechanics ,Simulation - Abstract
Biventricular (BiV) finite element (FE) models of cardiac electromechanics are evolving to a state where they can assist in clinical decision making. Carefully designed patient-specific geometries are combined with generic myofiber orientation data, because of lack of accurate techniques to measure myofiber orientation. However, it remains unclear to what extent the assumption of a generic myofiber orientation influences predictions on cardiac function from BiV FE models. As an alternative approach, it was suggested to let the myofiber orientation adapt in response to fiber cross-fiber shear. The aim of this study was to investigate to what extent variations in myofiber orientation as induced by adaptive myofiber reorientation caused variations in global stroke work in a BiV FE model and whether the adaptation model could be used as an alternative approach to prescribe the myofiber orientation in these models. An average change in myofiber orientation over an angle of about 8\(^\circ \), predominantly in transmural direction, resulted in a 91 % increase of LV and 20 % increase of RV stroke work. These findings indicate the importance for a more thorough effort to address a realistic myofiber orientation. The currently used model for adaptive myofiber reorientation seems a useful approach to prescribe the myofiber orientations in BiV FE models.
- Published
- 2015
8. Towards model assisted improvement of lead placement in Cardiac Resynchronization Therapy
- Author
-
Pluijmert, M.H., Kroon, W., Delhaas, T., Prinzen, F.W., Bovendeerd, P.H.M., and Cardiovascular Biomechanics
- Published
- 2014
9. Mechanically induced remodeling of left ventricular myofiber orientation
- Author
-
Pluijmert, M.H., Kroon, W., Prinzen, F.W., Delhaas, T., Bovendeerd, P.H.M., and Cardiovascular Biomechanics
- Published
- 2013
10. Selecting the optimal location for arteriovenous fistula surgery: the lifeline for hemodialysis treatment
- Author
-
Huberts, W., Kroon, W., Bode, A.S., Bosboom, E.M.H., Linden, van der, W.P.M., Planken, R.N., Tordoir, J.H.M., Vosse, van de, F.N., and Cardiovascular Biomechanics
- Published
- 2011
11. Patient-specific modelling of cardiac electrophysiology in heart-failure patients
- Author
-
Potse, M., primary, Krause, D., additional, Kroon, W., additional, Murzilli, R., additional, Muzzarelli, S., additional, Regoli, F., additional, Caiani, E., additional, Prinzen, F. W., additional, Krause, R., additional, and Auricchio, A., additional
- Published
- 2014
- Full Text
- View/download PDF
12. AV-fistula maturation: the failure rate reduced?
- Author
-
Huberts, W., Bosboom, E.M.H., Bode, A.S., Kroon, W., Tordoir, J.H.M., Vosse, van de, F.N., and Cardiovascular Biomechanics
- Abstract
No abstract.
- Published
- 2009
13. Bullying and Cyberbullying in Adolescence and its relations with Life satisfaction, Loneliness, Depressive symptoms and Reputation
- Author
-
Kroon, W. and Kroon, W.
- Abstract
The present study investigated the relation between bullying, cyberbullying, life satisfaction, loneliness, depressive symptoms and reputation. Participants were 484 adolescents aged 11 to 17 years (55,2 % male) drawn from two public schools in Valencia (Spain). Statistical analyses were carried out to examine the relation between bullying and cyberbullying and life satisfaction, loneliness and depressive symptoms and to examine the presence of a mediator in these relationships. Results revealed that there is a significant negative correlation between bullying and life satisfaction and between cyberbullying and life satisfaction. The results also revealed that there is a significant positive correlation between bullying and loneliness and between bullying and depressive symptoms. Similar to bullying, a significant positive relation between cyberbullying and loneliness and between cyberbullying and depressive symptoms has been found. Furthermore, results revealed that the adolescent’s own idea about his or her reputation in the peer group is a partial mediator in the relation between bullying and loneliness. In the relation between cyberbullying and life satisfaction, loneliness and depressive symptoms and in the relation between bullying and life satisfaction and depressive symptoms, the adolescent’s own idea about his or her reputation was not found to be a mediator.
- Published
- 2011
14. Olie op strooisel verlaagt stofconcentratie maar kort : proeven op praktijkbedrijf en in PDLT-proefstallen
- Author
-
Ellen, H.H. and Kroon, W.
- Subjects
poultry housing ,Praktijkonderzoek Pluimveehouderij "Het Spelderholt" ,broilers ,litter ,pluimveehokken ,exposure ,vleeskuikens ,plantaardige oliën ,stof ,dust ,plant oils ,blootstelling ,ligstro - Abstract
In een onderzoek is het direct aanbrengen van (koolzaad)olie op strooisel onderzocht. Dit bleek goed te werken, maar helaas slechts gedurende enkele dagen
- Published
- 1999
15. Quantitative method to determine smooth muscle cell orientation in vital arteries
- Author
-
Spronck, B., Merken, J.J., Kroon, W., Megens, R.T.A., Reesink, K.D., and Delhaas, T.
- Published
- 2012
- Full Text
- View/download PDF
16. Removal of enteric viruses from surface water at eight waterworks in The Netherlands
- Author
-
van Olphen, M, primary, Kapsenberg, J G, additional, van de Baan, E, additional, and Kroon, W A, additional
- Published
- 1984
- Full Text
- View/download PDF
17. Recruitment limitation along disturbance gradients in river floodplains
- Author
-
van Eck, van de Steeg, Blom, de Kroon, W. H J. M., H. M., C. W P. M., H., van Eck and Chiarucci, A.
- Published
- 2005
- Full Text
- View/download PDF
18. An exploratory study of structural and microvascular changes in the skin following electrical shaving using optical coherence topography.
- Author
-
Chaturvedi P, Kroon W, Zanelli G, and Worsley PR
- Subjects
- Humans, Male, Adult, Forearm blood supply, Young Adult, Microvessels diagnostic imaging, Microvessels physiology, Cheek blood supply, Cheek diagnostic imaging, Water Loss, Insensible physiology, Healthy Volunteers, Skin Physiological Phenomena, Electric Stimulation, Neck diagnostic imaging, Neck blood supply, Microcirculation physiology, Tomography, Optical Coherence methods, Skin blood supply, Skin diagnostic imaging
- Abstract
Background: Consumer products such as electrical shavers exert a combination of dynamic loading in the form of pressure and shear on the skin. This mechanical stimulus can lead to discomfort and skin tissue responses characterised as "Skin Sensitivity". To minimise discomfort following shaving, there is a need to establish specific stimulus-response relationships using advanced tools such as optical coherence tomography (OCT)., Objective: To explore the spatial and temporal changes in skin morphology and microvascular function following an electrical shaving stimulus., Methods: Ten healthy male volunteers were recruited. The study included a 60-s electrical shaving stimulus on the forearm, cheek and neck. Skin parameters were recorded at baseline, 20 min post stimulus and 24 h post stimulus. Structural and dynamic skin parameters were estimated using OCT, while transepidermal water loss (TEWL) was recorded to provide reference values for skin barrier function., Results: At baseline, six of the eight parameters revealed statistically significant differences between the forearm and the facial sites, while only surface roughness (Rq) and reflectivity were statistically different (p < 0.05) between the cheek and neck. At 20 min post shaving, there was a significant increase in the TEWL values accompanied by increased blood perfusion, with varying magnitude of change dependent on the anatomical site. Recovery characteristics were observed 24 h post stimulus with most parameters returning to basal values, highlighting the transient influence of the stimulus., Conclusions: OCT parameters revealed spatial and temporal differences in the skin tissue response to electrical shaving. This approach could inform shaver design and prevent skin sensitivity., (© 2024 The Author(s). Skin Research and Technology published by John Wiley & Sons Ltd.)
- Published
- 2024
- Full Text
- View/download PDF
19. Quantifying skin sensitivity caused by mechanical insults: A review.
- Author
-
Chaturvedi P, Worsley PR, Zanelli G, Kroon W, and Bader DL
- Subjects
- Epidermis, Erythema, Humans, Sebum, Skin, Skin Physiological Phenomena
- Abstract
Background: Skin sensitivity (SS) is a commonly occurring response to a range of stimuli, including environmental conditions (e.g., sun exposure), chemical irritants (e.g., soaps and cosmetics), and mechanical forces (e.g., while shaving). From both industry and academia, many efforts have been taken to quantify the characteristics of SS in a standardised manner, but the study is hindered by the lack of an objective definition., Methods: A review of the scientific literature regarding different parameters attributed to the loss of skin integrity and linked with exhibition of SS was conducted. Articles included were screened for mechanical stimulation of the skin, with objective quantification of tissue responses using biophysical or imaging techniques. Additionally, studies where cohorts of SS and non-SS individuals were reported have been critiqued., Results: The findings identified that the structure and function of the stratum corneum and its effective barrier properties are closely associated with SS. Thus, an array of skin tissue responses has been selected for characterization of SS due to mechanical stimuli, including: transepidermal water loss, hydration, redness, temperature, and sebum index. Additionally, certain imaging tools allow quantification of the superficial skin layers, providing structural characteristics underlying SS., Conclusion: This review proposes a multimodal approach for identification of SS, providing a means to characterise skin tissue responses objectively. Optical coherence tomography (OCT) has been suggested as a suitable tool for dermatological research with clinical applications. Such an approach would enhance the knowledge underlying the multifactorial nature of SS and aid the development of personalised solutions in medical and consumer devices., (© 2021 The Authors. Skin Research and Technology published by John Wiley & Sons Ltd.)
- Published
- 2022
- Full Text
- View/download PDF
20. Identifying perfusion deficits on CT perfusion images using temporal similarity perfusion (TSP) mapping.
- Author
-
De Vis JB, Song S, Luby M, Dankbaar JW, Glen D, Reynolds R, Velthuis BK, Kroon W, Latour LL, and Bokkers RPH
- Subjects
- Aged, Brain diagnostic imaging, Brain Ischemia diagnostic imaging, Brain Mapping methods, Cerebral Arteries diagnostic imaging, Cerebral Arteries physiology, Cerebrovascular Circulation physiology, Clinical Trials as Topic, Computed Tomography Angiography methods, Cross-Sectional Studies, Female, Humans, Male, Middle Aged, Retrospective Studies, Stroke diagnostic imaging, Brain Ischemia physiopathology, Stroke physiopathology
- Abstract
Objectives: Deconvolution-derived maps of CT perfusion (CTP) data may be confounded by transit delays. We propose temporal similarity perfusion (TSP) analysis to decrease CTP maps' dependence on transit times and investigate its sensitivity to detect perfusion deficits., Methods: CTP data of acute stroke patients obtained within 9 h of symptom onset was analyzed using a delay-insensitive singular value decomposition method and with TSP. The TSP method applies an iterative process whereby a pixel's highest Pearson's R value is obtained through comparison of a pixel's time-shifted signal density time-series curve and the average whole brain signal density time-series curve. Our evaluation included a qualitative and quantitative rating of deconvolution maps (MTT, CBV, and TTP), of TSP maps, and of follow-up CT., Results: Sixty-five patients (mean 68 (SD 13) years, 34 male) were included. A perfusion deficit was identified in 90%, 86%, 65%, and 84% of MTT, TTP, CBV, and TSP maps. The agreement of MTT, TTP, and TSP with CT follow-up was comparable but noticeably lower for CBV. CBV had the best relationship with final infarct volume (R
2 = 0.77, p < 0.001), followed by TSP (R2 = 0.63, p < 0.001). Intra-rater agreement of an inexperienced reader was higher for TSP than for CBV/MTT maps (kappa's of 0.79-0.84 and 0.63-0.7). Inter-rater agreement for experienced readers was comparable across maps., Conclusions: TSP maps are easier to interpret for inexperienced readers. Perfusion deficits detected by TSP are smaller which may suggest less dependence on transit delays although more investigation is required., Key Points: • Temporal similarity perfusion mapping assesses CTP data based on similarities in signal time-curves. • TSP maps are comparable in perfusion deficit detection to deconvolution maps. • TSP maps are easier to interpret for inexperienced readers.- Published
- 2019
- Full Text
- View/download PDF
21. Determinants of biventricular cardiac function: a mathematical model study on geometry and myofiber orientation.
- Author
-
Pluijmert M, Delhaas T, de la Parra AF, Kroon W, Prinzen FW, and Bovendeerd PH
- Subjects
- Humans, Heart anatomy & histology, Heart physiology, Models, Theoretical, Myocardium cytology, Ventricular Function physiology
- Abstract
In patient-specific mathematical models of cardiac electromechanics, usually a patient-specific geometry and a generic myofiber orientation field are used as input, upon which myocardial tissue properties are tuned to clinical data. It remains unclear to what extent deviations in myofiber orientation and geometry between model and patient influence model predictions on cardiac function. Therefore, we evaluated the sensitivity of cardiac function for geometry and myofiber orientation in a biventricular (BiV) finite element model of cardiac mechanics. Starting out from a reference geometry in which myofiber orientation had no transmural component, two new geometries were defined with either a 27 % decrease in LV short- to long-axis ratio, or a 16 % decrease of RV length, but identical LV and RV cavity and wall volumes. These variations in geometry caused differences in both local myofiber and global pump work below 6 %. Variation of fiber orientation was induced through adaptive myofiber reorientation that caused an average change in fiber orientation of [Formula: see text] predominantly through the formation of a component in transmural direction. Reorientation caused a considerable increase in local myofiber work [Formula: see text] and in global pump work [Formula: see text] in all three geometries, while differences between geometries were below 5 %. The findings suggest that implementing a realistic myofiber orientation is at least as important as defining a patient-specific geometry. The model for remodeling of myofiber orientation seems a useful approach to estimate myofiber orientation in the absence of accurate patient-specific information.
- Published
- 2017
- Full Text
- View/download PDF
22. Grade of dysplasia and malignant transformation in adults with premalignant laryngeal lesions.
- Author
-
van Hulst AM, Kroon W, van der Linden ES, Nagtzaam L, Ottenhof SR, Wegner I, Gunning AC, Grolman W, and Braunius W
- Subjects
- Adult, Humans, Laryngeal Neoplasms pathology, Neoplasm Grading, Cell Transformation, Neoplastic, Laryngeal Neoplasms diagnosis, Larynx pathology, Precancerous Conditions pathology
- Abstract
Background: The purpose of this systematic review was to determine the significance of the grade of dysplasia in the development of invasive carcinoma., Methods: A systematic search was performed to identify all relevant evidence. Titles and abstracts were screened using predefined criteria. Remaining articles were critically appraised. Absolute risks and 95% confidence intervals (CIs) were calculated., Results: Seven articles were included. Four studies demonstrated an increased risk for the development of laryngeal carcinoma from mild, moderate, and severe dysplasia. Three studies showed an increased risk between the categories of mild and moderate dysplasia., Conclusion: The risk of malignant transformation seems to increase with the grade of dysplasia, although percentages between studies are highly dissimilar. The wide variety and overlapping 95% CIs make it difficult to formulate a strong recommendation. However, moderate dysplasia is more prone for malignant transformation than previously thought, which might influence follow-up and treatment decisions in the future. © 2015 Wiley Periodicals, Head Neck 38: E2284-E2290, 2016., (© 2015 Wiley Periodicals, Inc.)
- Published
- 2016
- Full Text
- View/download PDF
23. In vivo electromechanical assessment of heart failure patients with prolonged QRS duration.
- Author
-
Kroon W, Lumens J, Potse M, Suerder D, Klersy C, Regoli F, Murzilli R, Moccetti T, Delhaas T, Krause R, Prinzen FW, and Auricchio A
- Subjects
- Aged, Computer Simulation, Electrocardiography, Heart Ventricles physiopathology, Humans, Magnetic Resonance Spectroscopy, Myocardial Contraction physiology, Heart Failure physiopathology
- Abstract
Background: Combined measurement of electrical activation and mechanical dyssynchrony in heart failure (HF) patients is scarce but may contain important mechanistic and diagnostic clues., Objective: The purpose of this study was to characterize the electromechanical (EM) coupling in HF patients with prolonged QRS duration., Methods: Ten patients with QRS width >120 ms underwent left ventricular (LV) electroanatomic contact mapping using the Noga® XP system (Biosense Webster). Recorded voltages during the cardiac cycle were converted to maps of depolarization time (TD). Electrode positions were tracked and converted into maps of time-to-peak shortening (TPS) using custom-made deformation analysis software. Correlation analysis was performed between the 2 maps to quantify EM coupling. Simulations with the CircAdapt cardiovascular system model were performed to mechanistically unravel the observed relation between TD and TPS., Results: The delay between earliest LV electrical activation and peak shortening differed considerably between patients (TPSmin-TDmin = 360 ± 73 ms). On average, total mechanical dyssynchrony exceeded total electrical activation (ΔTPS = 177 ± 47 ms vs ΔTD = 93 ± 24 ms, P <.001), but a large interpatient variability was observed. The TD and TPS maps correlated strongly in all patients (median R = 0.87, P <.001). These correlations were similar for regions with unipolar voltages above and below 6mV (Mann-Whitney U test, P = .93). Computer simulations revealed that increased passive myocardial stiffness decreases ΔTPS relative to ΔTD and that lower contractility predominantly increases TPSmin-TDmin., Conclusion: EM coupling in HF patients is maintained, but the relationship between TD and TPS differs strongly between patients. Intra-individual and inter-individual differences may be explained by local and global differences in passive and contractile myocardial properties., (Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
24. Assessment and comparison of left ventricular shear in normal and situs inversus totalis hearts by means of magnetic resonance tagging.
- Author
-
Rossi AC, Pluijmert M, Bovendeerd PH, Kroon W, Arts T, and Delhaas T
- Subjects
- Adolescent, Adult, Case-Control Studies, Child, Female, Heart Ventricles pathology, Humans, Magnetic Resonance Imaging, Male, Myocytes, Cardiac physiology, Situs Inversus pathology, Torsion, Mechanical, Heart Ventricles physiopathology, Myocardial Contraction, Shear Strength, Situs Inversus physiopathology
- Abstract
Situs inversus totalis (SIT) is characterized by complete mirroring of gross cardiac anatomy and position combined with an incompletely mirrored myofiber arrangement, being normal at the apex but inverted at the base of the left ventricle (LV). This study relates myocardial structure to mechanical function by analyzing and comparing myocardial deformation patterns of normal and SIT subjects, focusing especially on circumferential-radial shear. In nine control and nine SIT normotensive human subjects, myocardial deformation was assessed from magnetic resonance tagging (MRT) image sequences of five LV short-axis slices. During ejection, no significant difference in either circumferential shortening (εcc) or its axial gradient (Δεcc) is found between corresponding LV levels in control and SIT hearts. Circumferential-radial shear (εcr) has a clear linear trend from apex-to-base in controls, while in SIT it hovers close to zero at all levels. Torsion as well as axial change in εcr (Δεcr) is as in controls in apical sections of SIT hearts but deviates significantly towards the base, changing sign close to the LV equator. Interindividual variability in torsion and Δεcr values is higher in SIT than in controls. Apex-to-base trends of torsion and Δεcr in SIT, changing sign near the LV equator, further substantiate a structural transition in myofiber arrangement close to the LV equator itself. Invariance of εcc and Δεcc patterns between controls and SIT subjects shows that normal LV pump function is achieved in SIT despite partial mirroring of myocardial structure leading to torsional and shear patterns that are far from normality., (Copyright © 2015 the American Physiological Society.)
- Published
- 2015
- Full Text
- View/download PDF
25. Effects of activation pattern and active stress development on myocardial shear in a model with adaptive myofiber reorientation.
- Author
-
Pluijmert M, Bovendeerd PH, Kroon W, Prinzen FW, and Delhaas T
- Subjects
- Computer Simulation, Stress, Mechanical, Ventricular Function, Left physiology, Models, Cardiovascular, Myocardial Contraction physiology, Myocardium metabolism, Ventricular Remodeling physiology
- Abstract
It has been hypothesized that myofiber orientation adapts to achieve a preferred mechanical loading state in the myocardial tissue. Earlier studies tested this hypothesis in a combined model of left ventricular (LV) mechanics and remodeling of myofiber orientation in response to fiber cross-fiber shear, assuming synchronous timing of activation and uniaxial active stress development. Differences between computed and measured patterns of circumferential-radial shear strain E(cr) were assumed to be caused by limitations in either the LV mechanics model or the myofiber reorientation model. Therefore, we extended the LV mechanics model with a physiological transmural and longitudinal gradient in activation pattern and with triaxial active stress development. We investigated the effects on myofiber reorientation, LV function, and deformation. The effect on the developed pattern of the transverse fiber angle α(t,0) and the effect on global pump function were minor. Triaxial active stress development decreased amplitudes of E(cr) towards values within the experimental range and resulted in a similar base-to-apex gradient during ejection in model computed and measured E(cr). The physiological pattern of mechanical activation resulted in better agreement between computed and measured strain in myofiber direction, especially during isovolumic contraction phase and first half of ejection. In addition, remodeling was favorable for LV pump and myofiber function. In conclusion, the outcome of the combined model of LV mechanics and remodeling of myofiber orientation is found to become more physiologic by extending the mechanics model with triaxial active stress development and physiological activation pattern.
- Published
- 2014
- Full Text
- View/download PDF
26. Ureter smooth muscle cell orientation in rat is predominantly longitudinal.
- Author
-
Spronck B, Merken JJ, Reesink KD, Kroon W, and Delhaas T
- Subjects
- Animals, Rats, Rats, Wistar, Muscle, Smooth physiology, Myocytes, Smooth Muscle physiology, Peristalsis physiology, Ureter physiology
- Abstract
In ureter peristalsis, the orientation of the contracting smooth muscle cells is essential, yet current descriptions of orientation and composition of the smooth muscle layer in human as well as in rat ureter are inconsistent. The present study aims to improve quantification of smooth muscle orientation in rat ureters as a basis for mechanistic understanding of peristalsis. A crucial step in our approach is to use two-photon laser scanning microscopy and image analysis providing objective, quantitative data on smooth muscle cell orientation in intact ureters, avoiding the usual sectioning artifacts. In 36 rat ureter segments, originating from a proximal, middle or distal site and from a left or right ureter, we found close to the adventitia a well-defined longitudinal smooth muscle orientation. Towards the lamina propria, the orientation gradually became slightly more disperse, yet the main orientation remained longitudinal. We conclude that smooth muscle cell orientation in rat ureter is predominantly longitudinal, though the orientation gradually becomes more disperse towards the proprial side. These findings do not support identification of separate layers. The observed longitudinal orientation suggests that smooth muscle contraction would rather cause local shortening of the ureter, than cause luminal constriction. However, the net-like connective tissue of the ureter wall may translate local longitudinal shortening into co-local luminal constriction, facilitating peristalsis. Our quantitative, minimally invasive approach is a crucial step towards more mechanistic insight into ureter peristalsis, and may also be used to study smooth muscle cell orientation in other tube-like structures like gut and blood vessels.
- Published
- 2014
- Full Text
- View/download PDF
27. U-shaped mechanical activation 4 U?
- Author
-
Prinzen FW, Kroon W, and Auricchio A
- Subjects
- Female, Humans, Male, Bundle-Branch Block diagnosis, Bundle-Branch Block therapy, Cardiac Resynchronization Therapy, Magnetic Resonance Imaging, Cine, Myocardial Contraction, Ventricular Function, Left
- Published
- 2013
- Full Text
- View/download PDF
28. Computational model for estimating the short- and long-term cardiac response to arteriovenous fistula creation for hemodialysis.
- Author
-
Kroon W, Bosboom M, Huberts W, Tordoir J, and van de Vosse F
- Subjects
- Cardiac Output physiology, Computer Simulation, Heart anatomy & histology, Heart physiology, Humans, Myocardium, Ventricular Function, Arteriovenous Shunt, Surgical, Models, Cardiovascular, Renal Dialysis
- Abstract
Creation of an arteriovenous fistula (AVF) for hemodialysis may result in cardiac failure due to dramatic increases in cardiac output. To investigate the quantitative relations between AVF flow, changes in cardiac output, myocardial stress and strain and resulting left ventricular adaptation, a computational model is developed. The model combines a one-dimensional pulse wave propagation model of the arterial network with a zero-dimensional one-fiber model of cardiac mechanics and includes adaptation rules to capture the effect of the baro-reflex and long-term structural remodelling of the left ventricle. Using generic vascular and cardiac parameters based on literature, simulations are done that illustrate the model's ability to quantitatively reproduce the clinically observed increase in brachial flow and cardiac output as well as occurence of eccentric hypertrophy. Patient-specific clinical data is needed to investigate the value of the computational model for personalized predictions.
- Published
- 2012
- Full Text
- View/download PDF
29. Control of whole heart geometry by intramyocardial mechano-feedback: a model study.
- Author
-
Arts T, Lumens J, Kroon W, and Delhaas T
- Subjects
- Adaptation, Physiological physiology, Animals, Biomechanical Phenomena physiology, Dogs, Feedback, Physiological physiology, Hemodynamics, Mechanotransduction, Cellular physiology, Myocardium cytology, Myofibrils physiology, Heart anatomy & histology, Heart physiology, Models, Cardiovascular, Myocytes, Cardiac physiology
- Abstract
Geometry of the heart adapts to mechanical load, imposed by pressures and volumes of the cavities. We regarded preservation of cardiac geometry as a homeostatic control system. The control loop was simulated by a chain of models, starting with geometry of the cardiac walls, sequentially simulating circulation hemodynamics, myofiber stress and strain in the walls, transfer of mechano-sensed signals to structural changes of the myocardium, and finalized by calculation of resulting changes in cardiac wall geometry. Instead of modeling detailed mechano-transductive pathways and their interconnections, we used principles of control theory to find optimal transfer functions, representing the overall biological responses to mechanical signals. As biological responses we regarded tissue mass, extent of contractile myocyte structure and extent of the extra-cellular matrix. Mechano-structural stimulus-response characteristics were considered to be the same for atrial and ventricular tissue. Simulation of adaptation to self-generated hemodynamic load rendered physiologic geometry of all cardiac cavities automatically. Adaptation of geometry to chronic hypertension and volume load appeared also physiologic. Different combinations of mechano-sensors satisfied the condition that control of geometry is stable. Thus, we expect that for various species, evolution may have selected different solutions for mechano-adaptation.
- Published
- 2012
- Full Text
- View/download PDF
30. Patient-specific computational modeling of upper extremity arteriovenous fistula creation: its feasibility to support clinical decision-making.
- Author
-
Bode AS, Huberts W, Bosboom EM, Kroon W, van der Linden WP, Planken RN, van de Vosse FN, and Tordoir JH
- Subjects
- Blood Circulation, Feasibility Studies, Humans, Postoperative Period, Preoperative Period, Prospective Studies, Vascular Patency, Arteriovenous Shunt, Surgical, Computational Biology, Decision Making, Upper Extremity blood supply
- Abstract
Introduction: Inadequate flow enhancement on the one hand, and excessive flow enhancement on the other hand, remain frequent complications of arteriovenous fistula (AVF) creation, and hamper hemodialysis therapy in patients with end-stage renal disease. In an effort to reduce these, a patient-specific computational model, capable of predicting postoperative flow, has been developed. The purpose of this study was to determine the accuracy of the patient-specific model and to investigate its feasibility to support decision-making in AVF surgery., Methods: Patient-specific pulse wave propagation models were created for 25 patients awaiting AVF creation. Model input parameters were obtained from clinical measurements and literature. For every patient, a radiocephalic AVF, a brachiocephalic AVF, and a brachiobasilic AVF configuration were simulated and analyzed for their postoperative flow. The most distal configuration with a predicted flow between 400 and 1500 ml/min was considered the preferred location for AVF surgery. The suggestion of the model was compared to the choice of an experienced vascular surgeon. Furthermore, predicted flows were compared to measured postoperative flows., Results: Taken into account the confidence interval (25(th) and 75(th) percentile interval), overlap between predicted and measured postoperative flows was observed in 70% of the patients. Differentiation between upper and lower arm configuration was similar in 76% of the patients, whereas discrimination between two upper arm AVF configurations was more difficult. In 3 patients the surgeon created an upper arm AVF, while model based predictions allowed for lower arm AVF creation, thereby preserving proximal vessels. In one patient early thrombosis in a radiocephalic AVF was observed which might have been indicated by the low predicted postoperative flow., Conclusions: Postoperative flow can be predicted relatively accurately for multiple AVF configurations by using computational modeling. This model may therefore be considered a valuable additional tool in the preoperative work-up of patients awaiting AVF creation.
- Published
- 2012
- Full Text
- View/download PDF
31. Why SIT works: normal function despite typical myofiber pattern in Situs Inversus Totalis (SIT) hearts derived by shear-induced myofiber reorientation.
- Author
-
Pluijmert M, Kroon W, Rossi AC, Bovendeerd PH, and Delhaas T
- Subjects
- Computational Biology, Heart physiology, Heart Ventricles physiopathology, Humans, Myocardium cytology, Torsion Abnormality physiopathology, Ventricular Function physiology, Models, Cardiovascular, Myofibrils physiology, Situs Inversus physiopathology
- Abstract
The left ventricle (LV) of mammals with Situs Solitus (SS, normal organ arrangement) displays hardly any interindividual variation in myofiber pattern and experimentally determined torsion. SS LV myofiber pattern has been suggested to result from adaptive myofiber reorientation, in turn leading to efficient pump and myofiber function. Limited data from the Situs Inversus Totalis (SIT, a complete mirror image of organ anatomy and position) LV demonstrated an essential different myofiber pattern, being normal at the apex but mirrored at the base. Considerable differences in torsion patterns in between human SIT LVs even suggest variation in myofiber pattern among SIT LVs themselves. We addressed whether different myofiber patterns in the SIT LV can be predicted by adaptive myofiber reorientation and whether they yield similar pump and myofiber function as in the SS LV. With a mathematical model of LV mechanics including shear induced myofiber reorientation, we predicted myofiber patterns of one SS and three different SIT LVs. Initial conditions for SIT were based on scarce information on the helix angle. The transverse angle was set to zero. During reorientation, a non-zero transverse angle developed, pump function increased, and myofiber function increased and became more homogeneous. Three continuous SIT structures emerged with a different location of transition between normal and mirrored myofiber orientation pattern. Predicted SIT torsion patterns matched experimentally determined ones. Pump and myofiber function in SIT and SS LVs are similar, despite essential differences in myocardial structure. SS and SIT LV structure and function may originate from same processes of adaptive myofiber reorientation.
- Published
- 2012
- Full Text
- View/download PDF
32. A numerical method of reduced complexity for simulating vascular hemodynamics using coupled 0D lumped and 1D wave propagation models.
- Author
-
Kroon W, Huberts W, Bosboom M, and van de Vosse F
- Subjects
- Algorithms, Arteries physiology, Blood Flow Velocity physiology, Blood Pressure physiology, Computer Simulation, Humans, Microcirculation physiology, Nonlinear Dynamics, Hemodynamics physiology, Models, Cardiovascular
- Abstract
A computational method of reduced complexity is developed for simulating vascular hemodynamics by combination of one-dimensional (1D) wave propagation models for the blood vessels with zero-dimensional (0D) lumped models for the microcirculation. Despite the reduced dimension, current algorithms used to solve the model equations and simulate pressure and flow are rather complex, thereby limiting acceptance in the medical field. This complexity mainly arises from the methods used to combine the 1D and the 0D model equations. In this paper a numerical method is presented that no longer requires additional coupling methods and enables random combinations of 1D and 0D models using pressure as only state variable. The method is applied to a vascular tree consisting of 60 major arteries in the body and the head. Simulated results are realistic. The numerical method is stable and shows good convergence.
- Published
- 2012
- Full Text
- View/download PDF
33. Determinants of left ventricular shear strain.
- Author
-
Bovendeerd PH, Kroon W, and Delhaas T
- Subjects
- Adult, Humans, Magnetic Resonance Imaging, Stress, Mechanical, Finite Element Analysis, Models, Cardiovascular, Myocardial Contraction physiology, Myocytes, Cardiac physiology, Ventricular Function, Left physiology
- Abstract
Mathematical models of cardiac mechanics can potentially be used to relate abnormal cardiac deformation, as measured noninvasively by ultrasound strain rate imaging or magnetic resonance tagging (MRT), to the underlying pathology. However, with current models, the correct prediction of wall shear strain has proven to be difficult, even for the normal healthy heart. Discrepancies between simulated and measured strains have been attributed to 1) inadequate modeling of passive tissue behavior, 2) neglecting active stress development perpendicular to the myofiber direction, or 3) neglecting crossover of myofibers in between subendocardial and subepicardial layers. In this study, we used a finite-element model of left ventricular (LV) mechanics to investigate the sensitivity of midwall circumferential-radial shear strain (E(cr)) to settings of parameters determining passive shear stiffness, cross-fiber active stress development, and transmural crossover of myofibers. Simulated time courses of midwall LV E(cr) were compared with time courses obtained in three healthy volunteers using MRT. E(cr) as measured in the volunteers during the cardiac cycle was characterized by an amplitude of approximately 0.1. In the simulations, a realistic amplitude of the E(cr) signal could be obtained by tuning either of the three model components mentioned above. However, a realistic time course of E(cr), with virtually no change of E(cr) during isovolumic contraction and a correct base-to-apex gradient of E(cr) during ejection, could only be obtained by including transmural crossover of myofibers. Thus, accounting for this crossover seems to be essential for a realistic model of LV wall mechanics.
- Published
- 2009
- Full Text
- View/download PDF
34. Computational modeling of volumetric soft tissue growth: application to the cardiac left ventricle.
- Author
-
Kroon W, Delhaas T, Arts T, and Bovendeerd P
- Subjects
- Biomechanical Phenomena, Computer Simulation, Finite Element Analysis, Growth, Humans, Models, Anatomic, Models, Biological, Models, Cardiovascular, Models, Statistical, Myocardium pathology, Software, Stress, Mechanical, Time Factors, Heart Ventricles anatomy & histology
- Abstract
As an initial step to investigate stimulus-response relations in growth and remodeling (G&R) of cardiac tissue, this study aims to develop a method to simulate 3D-inhomogeneous volumetric growth. Growth is regarded as a deformation that is decomposed into a plastic component which describes unconstrained growth and an elastic component to satisfy continuity of the tissue after growth. In current growth models, a single reference configuration is used that remains fixed throughout the entire growth process. However, considering continuous turnover to occur together with growth, such a fixed reference is unlikely to exist in reality. Therefore, we investigated the effect of tissue turnover on growth by incrementally updating the reference configuration. With both a fixed reference and an updated reference, strain-induced cardiac growth in magnitude of 30% could be simulated. However, with an updated reference, the amplitude of the stimulus for growth decreased over time, whereas with a fixed reference this amplitude increased. We conclude that, when modeling volumetric growth, the choice of the reference configuration is of great importance for the computed growth.
- Published
- 2009
- Full Text
- View/download PDF
35. Computational analysis of the myocardial structure: adaptation of cardiac myofiber orientations through deformation.
- Author
-
Kroon W, Delhaas T, Bovendeerd P, and Arts T
- Subjects
- Computer Simulation, Humans, Image Enhancement methods, Magnetic Resonance Imaging, Reproducibility of Results, Sensitivity and Specificity, Algorithms, Elasticity Imaging Techniques methods, Image Interpretation, Computer-Assisted methods, Models, Cardiovascular, Myocytes, Cardiac cytology, Myocytes, Cardiac physiology
- Abstract
Deformation and structure of the cardiac wall can be assessed non-invasively by imaging techniques such as magnetic resonance imaging. Understanding the (patho-)physiology that underlies the observed deformation and structure is critical for clinical diagnosis. However, much about the genesis of deformation and structure is unknown. In the present computational model study, we hypothesize that myofibers locally adapt their orientation to achieve minimal fiber-cross fiber shear strain during the cardiac cycle. This hypothesis was tested in a 3D finite element model of left ventricular (LV) mechanics by computation of tissue deformations and subsequent adaptation of initial myofiber orientations towards those in the deformed tissue. As a consequence of adaptation, local tissue peak stress, strain during ejection and stroke work density were all found to increase by at least 10%, as well as to become 50% more homogeneous throughout the wall. Global LV work (peak systolic pressure, stroke volume and stroke work) increased significantly as well (>9%). The model-predicted myofiber orientations were found to be similar to those in experiments. To the best of our knowledge the presented model is the first that is able to simultaneously predict a realistic myocardial structure as well as to account for the experimentally observed homogeneity in local mechanics.
- Published
- 2009
- Full Text
- View/download PDF
36. Structure and torsion in the normal and situs inversus totalis cardiac left ventricle. II. Modeling cardiac adaptation to mechanical load.
- Author
-
Kroon W, Delhaas T, Bovendeerd P, and Arts T
- Subjects
- Adaptation, Physiological, Computer Simulation, Heart Ventricles pathology, Heart Ventricles physiopathology, Humans, Models, Anatomic, Myocardial Contraction, Reproducibility of Results, Rotation, Situs Inversus physiopathology, Stress, Mechanical, Time Factors, Torsion Abnormality, Ventricular Dysfunction, Left physiopathology, Models, Cardiovascular, Myocardium pathology, Situs Inversus pathology, Ventricular Dysfunction, Left pathology
- Abstract
Mathematical models provide a suitable platform to test hypotheses on the relation between local mechanical stimuli and responses to cardiac structure and geometry. In the present model study, we tested hypothesized mechanical stimuli and responses in cardiac adaptation to mechanical load on their ability to estimate a realistic myocardial structure of the normal and situs inversus totalis (SIT) left ventricle (LV). In a cylindrical model of the LV, 1) mass was adapted in response to myofiber strain at the beginning of ejection and to global contractility (average systolic pressure), 2) cavity volume was adapted in response to fiber strain during ejection, and 3) myofiber orientations were adapted in response to myofiber strain during ejection and local misalignment between neighboring tissue parts. The model was able to generate a realistic normal LV geometry and structure. In addition, the model was also able to simulate the instigating situation in the rare SIT LV with opposite torsion and transmural courses in myofiber direction between the apex and base [Delhaas et al. (6)]. These results substantiate the importance of mechanical load in the formation and maintenance of cardiac structure and geometry. Furthermore, in the model, adapted myocardial architecture was found to be insensitive to fiber misalignment in the transmural direction, i.e., myofiber strain during ejection was sufficient to generate a realistic transmural variation in myofiber orientation. In addition, the model estimates that, despite differences in structure, global pump work and the mass of the normal and SIT LV are similar.
- Published
- 2008
- Full Text
- View/download PDF
37. Structure and torsion of the normal and situs inversus totalis cardiac left ventricle. I. Experimental data in humans.
- Author
-
Delhaas T, Kroon W, Decaluwe W, Rubbens M, Bovendeerd P, and Arts T
- Subjects
- Adolescent, Adult, Aged, Case-Control Studies, Child, Female, Heart Ventricles pathology, Heart Ventricles physiopathology, Humans, Magnetic Resonance Imaging, Cine, Male, Middle Aged, Models, Anatomic, Models, Cardiovascular, Rotation, Situs Inversus physiopathology, Systole, Time Factors, Torsion Abnormality, Ventricular Dysfunction, Left physiopathology, Myocardium pathology, Situs Inversus pathology, Ventricular Dysfunction, Left pathology
- Abstract
In 1926, the famous American pediatric cardiologist, Dr. Helen B. Taussig, observed that in situs inversus totalis (SIT) main gross anatomical structures and the deep muscle bundles of the ventricles were a mirror image of the normal structure, while the direction of the superficial muscle bundles remained unchanged (H. B. Taussig, Bull Johns Hopkins Hosp 39: 199-202, 1926). She and we wondered about the implication of this observation for left ventricular (LV) deformation in SIT. We used magnetic resonance tagging to obtain information on LV deformation, rotation, and torsion from a series of tagged images in five evenly distributed, parallel, short-axis sections of the heart of nine controls and eight persons with SIT without other structural (cardiac) defect. In the controls, during ejection, the apex rotated counterclockwise with respect to the base, when looking from the apex. Furthermore, the base-to-apex gradient in rotation (torsion) was negative and similar at all longitudinal levels of the LV. In SIT hearts, torsion was positive near the base, indicating mirrored myofiber orientations compared with the normal LV. Contrary to expectations, torsion in the apical regions of SIT LVs was as in normal ones, reflecting a normal internal myocardial architecture. The transition zone with zero torsion, found between the apex and base, suggests that the heart structure in SIT is essentially different from that in the normal heart. This provides a unique possibility to study regulatory mechanisms for myocardial fiber orientation and mechanical load, which has been dealt with in the companion paper by Kroon et al.
- Published
- 2008
- Full Text
- View/download PDF
38. Left ventricular apical torsion and architecture are not inverted in situs inversus totalis.
- Author
-
Delhaas T, Kroon W, Bovendeerd P, and Arts T
- Subjects
- Adolescent, Adult, Child, Female, Heart Ventricles physiopathology, Humans, Male, Middle Aged, Situs Inversus physiopathology, Ventricular Function, Left
- Abstract
Occasionally, individuals have a complete, mirror-image reversal of their internal organ position, called situs inversus totalis (SIT). Whereas gross anatomy is mirror-imaged in SIT, this might not be the case for the internal architecture of organs, e.g. the myofiber pattern in the left cardiac ventricle. We performed a Magnetic Resonance Tagging study in nine controls and in eight subjects with SIT to assess the deformation pattern in the apical half of the LV wall. It appeared that both groups had the same LV apical deformation pattern. This implies that not only the superficial LV apical layers in SIT follow a normal, not inverted pattern, but the deeper layers as well. Apparently, the embryonic L/R controlling genetic pathway does determine situs-specific gross anatomy morphogenesis but it is not the only factor regulating fiber architecture within the apical part of the LV wall. We propose that mechanical forces generated in the not-inverted molecular structure of the basic right-handed helical contractile components of the sarcomere play a role in shaping the LV apex.
- Published
- 2008
- Full Text
- View/download PDF
39. [Therapeutic alternatives in benign prostatic hyperplasia].
- Author
-
Isa Kroon WA and Robles García JE
- Subjects
- 5-alpha Reductase Inhibitors, Adrenergic alpha-Antagonists therapeutic use, Catheterization, Humans, Hyperthermia, Induced, Male, Prostatic Hyperplasia therapy
- Published
- 1993
40. [Diagnosis of cancer of the prostate by determining the blood levels of specific prostatic antigen, rectal examination, and transrectal echography].
- Author
-
Isa Kroon WA, Robles JE, de Castro F, Rosell D, Abad JI, Zudaire JJ, and Berián JM
- Subjects
- Aged, Aged, 80 and over, Humans, Male, Middle Aged, Predictive Value of Tests, Prostatic Neoplasms blood, Rectum, Sensitivity and Specificity, Ultrasonography methods, Palpation methods, Prostate-Specific Antigen blood, Prostatic Neoplasms diagnosis
- Abstract
The usefulness of Prostate Specific Antigen (PSA), tactile rectal examination (TRE) and transrectal ultrasound (TRU) for the diagnosis of prostate cancer (PCa) was studied in 114 patients who came in for an evaluation of their mictional symptoms. Patients underwent random ultrasound-guided transrectal biopsies following findings of abnormal TRE and/or serum PSA concentrations > 5 ng/ml. Of the total series, 71% presented TRE abnormalities and 52% presented hypoechoic areas in the TRU (only ones to be considered suspicious). Also, 26%, 23% and 51% of patients presented normal (0-5 ng/ml), intermediate (5-10 ng/ml), and high (> 10 ng/ml) concentrations of serum PSA. Incidence of PCa was 31%. Based on the individual tests, both positive and negative predictive values were higher for serum PSA concentrations > 10 ng/ml. By combining the tests results, the diagnosis percentage was also higher with PSA levels > 10 ng/ml. Positive predictive value was 81% in patients with all three tests positive, 73% with suspicious TRE and high PSA and 70% with suspicious TRU and high PSA. Our results corroborate the superiority and efficacy of random biopsies over selective biopsies of hyperechoic areas. Nevertheless, of 21 patients with negative prostate biopsies who underwent TUR or retropubical adenomectomy, 28% had PCa. These findings indicate that random biopsies are associated with a percentage of false negatives which varies depending on the features of the sample being studied. In conclusion, PSA is the ideal complement to TRE, and the association of these two tests constitutes the best indication for an ultrasound-guided random prostate biopsy, with independence of any TRU findings.
- Published
- 1993
41. [Clinico-pathologic correlation in patients undergoing surgical staging and radical prostatectomy for prostatic cancer].
- Author
-
Isa Kroon WA, De Castro Barbosa F, Abad Vivas-Perez JI, Robles García JE, Zudaire Bergera JJ, and Berián Polo JM
- Subjects
- Aged, Humans, Lymph Node Excision, Lymphatic Metastasis, Male, Middle Aged, Neoplasm Invasiveness, Neoplasm Staging, Prostate-Specific Antigen blood, Prostatectomy, Prostatic Neoplasms blood, Prostatic Neoplasms surgery, Prostatic Neoplasms pathology
- Abstract
Presentation of our experience on the clinico-pathological staging of clinically localized prostate cancer (PCa) in 38 patients undergoing staging lymphadenectomy, 34 of which were treated with radical prostatectomy. From total number of patients, 37% were correctly staged, 60% were under-staged and only 3% were over-staged. A total of 11 patients (29%) presented nodular metastasis at the time of lymphadenectomy. Out of the 34 patients undergoing radical prostatectomy, 10 (29%) had microscopical invasion of prostatic capsule and seminal vesicles infiltration. The likelihood of nodes affectation in patients with prostatic capsule invasion and seminal vesicles infiltration was 60% and 70%, respectively. Mean PSA was significantly higher in patients with advanced disease as compared to those with disease localized in the prostatic gland. Also, mean PSA was significantly higher in patients with prostatic capsule invasion and seminal vesicles infiltration. The analysis by logistic regression identified pre-operative PSA as the only variable significantly correlated to the patient's final pathological stage.
- Published
- 1993
42. [Pure squamous carcinoma of the ureter. Review of a case].
- Author
-
Assad Isa Kroon W, Robles García JE, Aguera Fernández LG, de Castro Barbosa F, Sánchez de la Muela PL, Rosell Costa D, Lozano Escario MD, Zudaire Bergera JJ, and Berián Polo JM
- Subjects
- Carcinoma, Squamous Cell surgery, Humans, Male, Metaplasia, Middle Aged, Ureteral Neoplasms surgery, Carcinoma, Squamous Cell pathology, Ureteral Neoplasms pathology
- Abstract
We report a case of squamous cell carcinoma of the ureter with periureteral infiltration. Three years following radical surgery, no evidence of tumor progression has been observed. Only 1% to 1.6% of urothelial tumors of the upper urinary tract are purely squamous cell tumors. This tumor type carries a poor prognosis. Currently, the best results can be achieved by early diagnosis and radical surgery.
- Published
- 1992
43. [Tumor thrombosis in inferior vena cava: diagnostic imaging and therapeutic approximation].
- Author
-
De Castro Barbosa F, Robles García JE, Rosell Costa D, Agüera Fernández L, Isa Kroon W, Sánchez de la Muela P, Zudaire Bergera JJ, and Berián Polo JM
- Subjects
- Humans, Magnetic Resonance Imaging, Neoplasms diagnostic imaging, Neoplasms therapy, Retrospective Studies, Tomography, X-Ray Computed, Ultrasonography, Neoplastic Cells, Circulating, Vena Cava, Inferior diagnostic imaging
- Abstract
Review of our experience in the diagnosis and treatment of 44 patients with inferior vena cava tumoral thrombosis (IVCTT), associated or not to other neoplastic processes: 34 hypernephroma, 2 cava leiomyosarcoma, 1 paratesticular rhabdomyosarcoma and 1 biphasic synovial sarcoma. Twenty-five patients with hypernephroma and tumor thrombi in the ipsilateral renal vein only were excluded from the analysis since this fact did not change the usual therapeutic approach. In the 19 remaining patients, concomitantly to the primary tumour exeresis a thrombectomy was performed, using cavotomy with proximal and distal clamping in 11 patients and cardiopulmonary by-pass, deep hypothermia and cardiocirculatory arrest in 8 patients. The paper analyzes the radiological investigations performed in order to reach a IVCTT diagnosis, and reviews the related literature.
- Published
- 1992
44. [Specific prostatic antigen: usefulness in clinical practice].
- Author
-
Isa Kroon WA, Sánchez de la Muela PL, and Berian Polo JM
- Subjects
- Follow-Up Studies, Humans, Male, Neoplasm Staging, Prostate-Specific Antigen, Prostatic Neoplasms pathology, Antigens, Neoplasm blood, Biomarkers, Tumor blood, Prostatic Neoplasms blood
- Published
- 1992
45. [Kidney pelvis tumor in ectopic kidney. Report of a case].
- Author
-
Isa Kroon WA, de Castro Barbosa F, Sánchez de la Muela PL, Robles García JE, Zudaire Bergera JJ, and Berián Polo JM
- Subjects
- Humans, Kidney diagnostic imaging, Kidney Neoplasms diagnostic imaging, Male, Middle Aged, Tomography, X-Ray Computed, Kidney abnormalities, Kidney Neoplasms complications, Kidney Pelvis
- Abstract
A case of urothelial carcinoma in pelvic ectopic kidney is described. The low incidence of both pathologies and their rare association justifies the description.
- Published
- 1992
46. [Infiltrating bladder carcinoma with metastatic lymph node involvement: radical treatment and survival].
- Author
-
de Castro Barbosa F, Sánchez de la Muela P, Rosell Costa D, Aguera Fernández L, Isa Kroon W, Robles García JE, Zudaire Bergera JJ, and Berián Polo JM
- Subjects
- Actuarial Analysis, Carcinoma, Transitional Cell mortality, Carcinoma, Transitional Cell pathology, Carcinoma, Transitional Cell therapy, Combined Modality Therapy, Follow-Up Studies, Humans, Lymphatic Metastasis, Survival Rate, Urinary Bladder Neoplasms mortality, Urinary Bladder Neoplasms pathology, Urinary Bladder Neoplasms therapy, Carcinoma, Transitional Cell surgery, Urinary Bladder Neoplasms surgery
- Abstract
Presentation of the results obtained from the study of 64 patients with T2-4 stage vesical carcinoma, treated with radical cystectomy, local lymphadenectomy, with and without complementary radiotherapy, with and without neoadjuvant chemotherapy. The univariate study of 19/64 patients with microscopic nodular disease revealed a significant relationship with the pathological stage but not with the clinical stage. The multivariate study demonstrated that the most relevant prognostic factors are a decrease in tumoral stage (P) and the presence of vascular and/or lymphatic involvement in the TUR-biopsy. The analysis of survival confirms the poor prognosis of patients with metastatic nodular involvement, in spite of the association of pelvic radiotherapy or neoadjuvant chemotherapy to the treatment.
- Published
- 1992
47. [Tumors of the upper urothelium and cyclophosphamide: presentation of a case and review of the literature].
- Author
-
de Castro Barbosa F, Rosell Costa D, Agüera Fernández L, Isa Kroon WA, Sánchez de la Muela P, Robles García JE, Zudaire Bergera JJ, and Berián Polo JM
- Subjects
- BCG Vaccine therapeutic use, Carcinoma, Transitional Cell therapy, Combined Modality Therapy, Cyclophosphamide therapeutic use, Doxorubicin therapeutic use, Humans, Kidney Neoplasms surgery, Male, Middle Aged, Neoplasm Recurrence, Local, Neoplasms, Multiple Primary chemically induced, Neoplasms, Multiple Primary therapy, Nephrectomy, Urinary Bladder Neoplasms therapy, Waldenstrom Macroglobulinemia complications, Carcinoma, Transitional Cell chemically induced, Cyclophosphamide adverse effects, Kidney Neoplasms chemically induced, Urinary Bladder Neoplasms chemically induced, Waldenstrom Macroglobulinemia drug therapy
- Abstract
We report a case of upper urothelial tumor in a patient who had previously received prolonged cyclophosphamide therapy for Waldeström's macroglobulinemia. Although bladder tumors in cyclophosphamide-treated patients are relatively frequent, upper urothelial tumors are rare. Only 5 cases of this latter tumor type have been reported as of 1987. The literature on this disease entity is reviewed. Patients who have received prolonged therapy with cyclophosphamide or similar drugs must be followed very closely.
- Published
- 1991
48. [Paratesticular rhabdomyosarcoma with intracaval neoplastic involvement: presentation of a case and review of the literature].
- Author
-
De Castro Barbosa F, Rosell Costa D, Aguera Fernández LG, Isa Kroon W, Sánchez de la Muela P, Robles Garcia JE, Zudaire Bergera JJ, and Berian Polo JM
- Subjects
- Adolescent, Antineoplastic Combined Chemotherapy Protocols therapeutic use, Combined Modality Therapy, Dactinomycin administration & dosage, Doxorubicin administration & dosage, Female, Humans, Ifosfamide administration & dosage, Lymph Node Excision, Male, Orchiectomy, Radiotherapy, High-Energy, Vincristine administration & dosage, Genital Neoplasms, Male pathology, Genital Neoplasms, Male therapy, Neoplastic Cells, Circulating, Rhabdomyosarcoma pathology, Rhabdomyosarcoma therapy, Scrotum, Vena Cava, Inferior surgery
- Abstract
One case of paratesticular embryonal rhabdomyosarcoma (RMS), affected during its evolution by a tumoral thrombus in the inferior vena cava. This unusual association forced the use of a cardiopulmonary by-pass, profound hypothermia and circulatory arrest, in order to carry out complete exeresis of the damage. Also, revision of the literature emphasizing that today's therapeutical approach for RMS should essentially be multidisciplinary.
- Published
- 1991
49. [Hyperammonemia and transient blindness after transurethral resection of the prostate. Review of a case].
- Author
-
Isa Kroon WA, Aguera Fernández LG, Rosell Costa D, de Castro Barbosa F, Sánchez de la Muela PL, Robles García JE, Zudaire Bergera JJ, and Berián Polo JM
- Subjects
- Aged, Glycine blood, Humans, Male, Prostatectomy methods, Ammonia blood, Blindness etiology, Prostatectomy adverse effects
- Abstract
We report a case of hyperammonemia and transient blindness following transurethral prostatic resectin. Glicine and ammonia metabolism are reviewed. Water intoxication may not account for these symptoms.
- Published
- 1991
50. [Effect of time of vascular anastomosis and of hot and cold ischemia, on survival of cadaver renal graft].
- Author
-
Isa Kroon WA, Robles JE, Rosell D, Agüera LG, de Castro F, Sánchez de la Muela P, Zudaire JJ, Errasti P, and Berián JM
- Subjects
- Adult, Anastomosis, Surgical, Cadaver, Cold Temperature, Female, Follow-Up Studies, Hot Temperature, Humans, Kidney blood supply, Kidney surgery, Male, Retrospective Studies, Time Factors, Graft Survival, Kidney Transplantation methods
- Abstract
A retrospective study was performed on our series of 240 primary cadaveric renal transplant recipients to dissect the influence of vascular anastomosis time, warm ischemia time and cold ischemia time on ultimate graft survival. 177 patients received conventional immunosuppression with Azatioprine and steroids, and 63 patients received Cyclosporine A therapy. The data was analyzed for sub-groups of ischemia time and comparisons were performed using the method of Tarone-Ware. The present study fails to demonstrate a detrimental effect of ischemic insults on graft survival. The use of Cyclosporine A in the pre and post-transplant, monitoring periodically serum cyclosporine levels and the use of renal allograft biopsy, allows the use of this agent without a high incidence of nefrotoxicity.
- Published
- 1991
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.