liu.seSearch for publications in DiVA
Change search
Link to record
Permanent link

Direct link
BETA
Franzén, Stefan
Alternative names
Publications (6 of 6) Show all publications
Escobar Kvitting, J.-P., Dyverfeldt, P., Sigfridsson, A., Franzen, S., Wigström, L., Bolger, A. F. & Ebbers, T. (2010). In Vitro Assessment of Flow Patterns and Turbulence Intensity in Prosthetic Heart Valves Using Generalized Phase-Contrast MRI. JOURNAL OF MAGNETIC RESONANCE IMAGING, 31(5), 1075-1080
Open this publication in new window or tab >>In Vitro Assessment of Flow Patterns and Turbulence Intensity in Prosthetic Heart Valves Using Generalized Phase-Contrast MRI
Show others...
2010 (English)In: JOURNAL OF MAGNETIC RESONANCE IMAGING, ISSN 1053-1807, Vol. 31, no 5, p. 1075-1080Article in journal (Refereed) Published
Abstract [en]

Purpose: To assess in vitro the three-dimensional mean velocity field and the extent and degree of turbulence intensity (TI) in different prosthetic heart valves using a generalization of phase-contrast MRI (PC-MRI). Materials and Methods: Four 27-mm aortic valves (Bjork-Shiley Monostrut tilting-disc, St. Jude Medical Standard bileaflet, Medtronic Mosaic stented and Freestyle stentless porcine valve) were tested under steady inflow conditions in a Plexiglas phantom. Three-dimensional PC-MRI data were acquired to measure the mean velocity field and the turbulent kinetic energy (TKE), a direction-independent measure of TI. Results: Velocity and TI estimates could be obtained up and downstream of the valves, except where metallic structure in the valves caused signal void. Distinct differences in the location, extent, and peak values of velocity and TI were observed between the valves tested. The maximum values of TKE varied between the different valves: tilting disc, 100 J/m(3); bileaflet, 115 J/m(3); stented, 200 J/m(3); stentless, 145 J/m(3). Conclusion: The TI downstream from a prosthetic heart valve is dependent on the specific valve design. Generalized PC-MRI can be used to quantify velocity and TI downstream from prosthetic heart valves, which may allow assessment of these aspects of prosthetic valvular function in postoperative patients.

Place, publisher, year, edition, pages
John Wiley and Sons, Ltd, 2010
Keywords
turbulence intensity, prosthetic heart valves, phase-contrast magnetic resonance imaging
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-56524 (URN)10.1002/jmri.22163 (DOI)000277397100005 ()
Available from: 2010-05-21 Created: 2010-05-21 Last updated: 2013-09-03
Tamás, É., Broqvist, M., Olsson, E., Franzén, S. & Nylander, E. (2009). Exercise radionuclide ventriculography for predicting postoperative left ventricular function in chronic aortic regurgitation. JACC: Cardiovascular Imaging, 2(1), 48-55
Open this publication in new window or tab >>Exercise radionuclide ventriculography for predicting postoperative left ventricular function in chronic aortic regurgitation
Show others...
2009 (English)In: JACC: Cardiovascular Imaging, ISSN 1936-878X, Vol. 2, no 1, p. 48-55Article in journal (Refereed) Published
Abstract [en]

Objectives: Ejection fraction (EF) reaction upon exercise by radionuclide ventriculography and standard echocardiographic parameters was evaluated as predictors for post-operative left ventricular (LV) function in chronic aortic regurgitation (AR).

Background: The optimal timing of surgery for chronic AR is when the left ventricle is still compensating for the volume and pressure overload without irreversible dysfunction. For asymptomatic patients when EF is normal and LV diameters are borderline, exercise testing is recommended by present guidelines. However, only a limited number of studies have been performed, and data are scarce on this subject.

Methods: Radionuclide ventriculography with multiple gated acquisition at rest and during exercise was performed in 29 consecutive patients with severe chronic aortic regurgitation pre-operatively and 6 months post-operatively. Patient subgroups were formed based on pre-operative EF exercise response (ΔEF) and were categorized as decreasing (ΔEF <−5%), unaltered (−5% ≤ ΔEF ≤ 5%), and increasing (ΔEF > 5%). A 5% or higher increase was considered normal. The LV diameters and mass were measured by echocardiography.

Results: Pre-operative LV diameters were markedly elevated before surgery and diminished significantly after surgery. Left ventricular diameters, LV mass, EF at rest (EFrest), and EF change from rest to exercise (ΔEF) were independent of New York Heart Association functional class. Pre-operative end-diastolic diameter proved to be a predictor for pre- and post-operative ΔEF (p = 0.003; p = 0.04) but not for the nature of the exercise response post-operatively. Patients with decreasing and unaltered EF pre-operatively presented a significantly higher but still abnormal ΔEF post-operatively. Those with increasing EF pre-operatively had a similar response and a normal ΔEF post-operatively. Pre-operative ΔEF was not only a predictor for post-operative ΔEF (p = 0.02) but also classified patients into post-operative subgroups (EF decreasing, p = 0.03; unaltered, p = 0.02; increasing, p = 0.0008).

Conclusions: An abnormal EF response to exercise may also occur in patients who do not fulfill criteria for surgery based on LV dimensions or EF. A follow-up of exercise LV function and adjusting the timing of surgery according to the nature of exercise response could, therefore, be beneficial.

Place, publisher, year, edition, pages
Elsevier, 2009
Keywords
radionuclide ventriculography, ejection fraction, exercise testing, aortic regurgitation, cardiac surgery
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13338 (URN)10.1016/j.jcmg.2008.09.009 (DOI)000287651900008 ()
Available from: 2008-06-18 Created: 2008-06-18 Last updated: 2011-03-11
Dyverfeldt, P., Escobar Kvitting, J.-P., Sigfridsson, A., Franzén, S., Bolger, A. F. & Ebbers, T. (2009). In-Vitro Turbulence Mapping in Prosthetic Heart Valves using Generalized Phase-Contrast MRI. In: Proc. Intl. Soc. Mag. Reson. Med.. Paper presented at ISMRM (pp. 3941).
Open this publication in new window or tab >>In-Vitro Turbulence Mapping in Prosthetic Heart Valves using Generalized Phase-Contrast MRI
Show others...
2009 (English)In: Proc. Intl. Soc. Mag. Reson. Med., 2009, p. 3941-Conference paper, Published paper (Refereed)
National Category
Biomedical Laboratory Science/Technology
Identifiers
urn:nbn:se:liu:diva-58097 (URN)
Conference
ISMRM
Available from: 2010-08-23 Created: 2010-07-29 Last updated: 2013-09-03Bibliographically approved
Cardell, K., Widell, A., Frydén, A., Åkerlind, B., Månsson, A.-S., FranzÉn, S., . . . Isaksson, B. (2008). Nosocomial hepatitis C in a thoracic surgery unit, retrospective findings generating a prospective study. Journal of Hospital Infection, 68(4), 322-328
Open this publication in new window or tab >>Nosocomial hepatitis C in a thoracic surgery unit, retrospective findings generating a prospective study
Show others...
2008 (English)In: Journal of Hospital Infection, ISSN 0195-6701, E-ISSN 1532-2939, Vol. 68, no 4, p. 322-328Article in journal (Refereed) Published
Abstract [en]

We describe the transmission of hepatitis C virus (HCV) to two patients from a thoracic surgeon who was unaware of his hepatitis C infection. By partial sequencing of the non-structural 5B gene and phylogenetic analysis, the viruses from both patients were found to be closely related to genotype 1a strain from the surgeon. Two further hepatitis C cases were found in relation to the thoracic clinic. Their HCV sequences were related to each other but were of genotype 2b and the source of infection was never revealed. To elucidate the magnitude of the problem, we conducted a prospective study for a period of 17 months in which patients who were about to undergo thoracic surgery were asked to participate. Blood samples were drawn prior to surgery and at least four months later. The postoperative samples were then screened for anti-HCV and, if positive, the initial sample was also analysed. The only two patients (0.4%) identified were confirmed anti-HCV positive before surgery, and none out of 456 evaluable cases seroconverted to anti-HCV during the observation period. Despite the retrospectively identified cases, nosocomial hepatitis C is rare in our thoracic unit. The study points out the risk of transmission of hepatitis C from infected personnel and reiterates the need for universal precautions. © 2008 The Hospital Infection Society.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-43217 (URN)10.1016/j.jhin.2007.12.008 (DOI)72981 (Local ID)72981 (Archive number)72981 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
Escobar Kvitting, J.-P., Engvall, J., Broqvist, M., FranzÉn, S., Andersson, M., Ohlsson, U. & Nielsen, N. E. (2008). Recurrence of myxoma in the left ventricle with concurrent cerebral fusiform aneurysms after previous atrial myxoma surgery. Journal of Thoracic and Cardiovascular Surgery, 135(5), 1172-1173
Open this publication in new window or tab >>Recurrence of myxoma in the left ventricle with concurrent cerebral fusiform aneurysms after previous atrial myxoma surgery
Show others...
2008 (English)In: Journal of Thoracic and Cardiovascular Surgery, ISSN 0022-5223, E-ISSN 1097-685X, Vol. 135, no 5, p. 1172-1173Article in journal, Editorial material (Other academic) Published
Place, publisher, year, edition, pages
Maryland Heights, Missouri: Mosby, Inc., 2008
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-43542 (URN)10.1016/j.jtcvs.2007.12.020 (DOI)000255512800030 ()18455603 (PubMedID)2-s2.0-42949154752 (Scopus ID)74138 (Local ID)74138 (Archive number)74138 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13Bibliographically approved
Hager, J., Lundgren, F., Forssell, C., FranzÉn, S., Hermansson, U., Isaksson, L. & Vanhanen, I. (2005). Surgery for descending and thoracoabdominal aortic aneurysms. In: Kardiovaskulära vårmötet,2005.
Open this publication in new window or tab >>Surgery for descending and thoracoabdominal aortic aneurysms
Show others...
2005 (English)In: Kardiovaskulära vårmötet,2005, 2005Conference paper, Published paper (Other academic)
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-33854 (URN)19927 (Local ID)19927 (Archive number)19927 (OAI)
Available from: 2009-10-09 Created: 2009-10-09
Organisations

Search in DiVA

Show all publications