| 1. |
- Blomstrand, Peter, et al.
(författare)
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Pulsed tissue Doppler imaging for the detection of myocardial ischaemia, a comparison with myocardial perfusion SPECT
- 2004
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Ingår i: Clinical Physiology and Functional Imaging. - : John Wiley & Sons. - 1475-0961 .- 1475-097X. ; 24:5, s. 289-295
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Tidskriftsartikel (refereegranskat)abstract
- In order to compare the diagnostic ability of pulsed tissue Doppler and myocardial perfusion Single Photon Emission Computed Tomography (SPECT) in patients with a history of unstable coronary artery disease, CAD, 26 patients, 22 men and four women, age 47-76 years, were investigated in a prospective study, 5-10 day after an episode of unstable angina. Tissue Doppler and two-dimensional echocardiography were performed during dobutamine stress testing and myocardial scintigraphy after bicycle exercise and at rest. Patients with a normal SPECT had higher peak systolic velocity during dobutamine infusion, 18.9 ± 4.1 cm s-1, than patients with ischaemia, 12.2 ± 3.8 cm s-1 (P<0.001) or scar, 8.8 ± 3.0 cm s-1 (P<0.01). In a territorial analysis the difference in peak systolic velocity between areas with a normal and abnormal SPECT was less apparent. Failure to achieve ≥13 cm s-1 in mean-peak systolic velocity was the most accurate criterion for detection of significant CAD on SPECT. We conclude that pulsed tissue Doppler can be used for objective quantification of left ventricular wall motion during dobutamine stress testing and for identification of patients with CAD on SPECT but not for identification of regional ischaemia.
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| 2. |
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| 3. |
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| 4. |
- Ebbers, Tino, 1972-, et al.
(författare)
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Estimation of relative cardiovascular pressures using time-resolved three-dimensional phase contrast MRI
- 2001
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 0740-3194 .- 1522-2594. ; 45:5, s. 872-879
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Tidskriftsartikel (refereegranskat)abstract
- Accurate, easy-to-use, noninvasive cardiovascular pressure registration would be an important addition to the diagnostic armamentarium for assessment of cardiac function. A novel noninvasive and three-dimensional (3D) technique for estimation of relative cardiovascular pressures is presented. The relative pressure is calculated using the Navier-Stokes equations along user-defined lines placed within a time-resolved 3D phase contrast MRI dataset. The lines may be either straight or curved to follow an actual streamline. The technique is validated in an in vitro model and tested on in vivo cases of normal and abnormal transmitral pressure differences and intraaortic flow. The method supplements an intuitive visualization technique for cardiovascular flow, 3D particle trace visualization, with a quantifiable diagnostic parameter estimated from the same dataset.
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| 5. |
- Engvall, Jan, 1953-, et al.
(författare)
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Daytime ambulatory blood pressure correlates strongly with the echocardiographic diameter of aortic coarctation
- 2001
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 35:5, s. 335-339
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Tidskriftsartikel (refereegranskat)abstract
- Objective.-To relate the echocardiographic aortic arch-diameter to ambulatory and clinic blood pressure (BP) in patients with aortic coarctation. Design.-Eighteen adult patients (50% men) were recruited from the coarctation registry of the Linkoping Heart Centre. Biplane-trans-oesophageal echocardiography (TEE) was performed with Acuson XP 128/10, ambulatory BP was recorded with Spacelab models 90202/90205. Results.-Systolic clinic and ambulatory BP levels were higher in patients than in the 36 controls (clinic BP: 146 ▒ 25 mmHg vs 119 ▒ 10 mmHg, p = 0.0009, ambulatory BP: 140 ▒ 18 mmHg vs 124 ▒ 11 mmHg, p = 0.009). The differences in diastolic BP levels were less obvious (clinic BP: 87 ▒ 16 mmHg vs 76 ▒ 8 mmHg, p = 0.02, ambulatory BP: 84 ▒ 13 mmHg vs 77 ▒ 9 mmHg, p = 0.052). Daytime ambulatory BP was more strongly related than clinic BP to the coarctation diameter (AD) (systolic BP r = -0.73, p = 0.0006 and r = -0.61, p = 0.007, respectively). In surgically corrected patients (n = 14) only the correlations between ambulatory systolic daytime (r = -0.61, p = 0.02) and night-time (r = -0.58, p = 0.03) BP to AD was statistically significant. Conclusion.-Ambulatory BP correlates strongly with aortic coarctation measured by TEE and would thus be the preferred technique for evaluating BP in this patient category.
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| 6. |
- Escobar Kvitting, John-Peder, 1976-, et al.
(författare)
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Flow patterns in the aortic root and the aorta studied with time-resolved, 3-dimensional, phase-contrast magnetic resonance imaging : implications for aortic valve–sparing surgery
- 2004
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Ingår i: Journal of Thoracic and Cardiovascular Surgery. - : Elsevier BV. - 0022-5223 .- 1097-685X. ; 127:6, s. 1602-1607
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveSparing the aortic valve has become a surgical option for patients who require repair of aortic root ectasia and have normal valve leaflets. Surgical approaches to valve sparing differ with regard to preservation of the native sinuses of Valsalva. The role of the sinuses and the importance of maintaining them remain controversial.MethodsBy using a time-resolved, 3-dimensional, phase-contrast magnetic resonance imaging technique, aortic root and aortic blood velocity data were acquired from 2 patients with Marfan syndrome 6 months after aortic valve–sparing surgery with straight Dacron grafts and contrasted with data from 6 normal volunteers.ResultsIn normal aortas vortical blood flow became apparent in the individual sinuses after peak systole. The vortices filled the available space behind the valve leaflets and persisted until diastole, expanding and moving inward during aortic valve closure. In contrast, no vortices were observed in the postoperative patients with Marfan syndrome with negligible sinuses.ConclusionsChanges in supravalvular flow accompany loss of sinus architecture. Whether the presence, size, and velocity of supravalvular vortices affects the function or durability of the preserved aortic valve remains to be studied.
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| 7. |
- Escobar Kvitting, John-Peder, 1976-, et al.
(författare)
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Three-directional myocardial motion assessed using 3D phase contrast MRI
- 2004
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Ingår i: Journal of Cardiovascular Magnetic Resonance. - 1097-6647 .- 1532-429X. ; 6:3, s. 627-636
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Tidskriftsartikel (refereegranskat)abstract
- Regional myocardial function is a complex entity consisting of motion in three dimensions (3D). Besides magnetic resonance imaging (MRI), no other noninvasive technique can give a true 3D description of cardiac motion. Using a time‐resolved 3D phase contrast technique, three‐dimensional image volumes containing myocardial velocity data in six normal volunteers were acquired. Coordinates and velocity information were extracted from nine points placed in different myocardial segments in the left ventricle (LV), and decomposed into longitudinal (VL), radial (VR), and circumferential (VC) velocity components. Our findings confirm a longitudinal apex‐to‐base gradient for the LV, with only a small motion of the apex. The mean velocity for VL for all the basal segments was higher compared to the midsegments during systole [3.5 ± 1.2 vs. 2.5 ± 1.7 cm/s (p < 0.01)], early filling [− 6.9 ± 1.8 vs. − 4.9 ± 1.8 cm/s (p < 0.001)], and during atrial contraction [− 2.2 ± 1.4 vs. − 1.6 ± 1.3 cm/s (p < 0.05)]. A similar pattern was observed when comparing velocities from the midsegments to the apex. Radial velocity was higher during early filling in the midportion of the lateral [− 4.9 ± 2.7 vs. − 3.2 ± 1.6 cm/s (p < 0.05)] wall compared to the basal segments, no difference was observed for the septal [− 2.0 ± 1.5 vs. − 0.3 ± 2.5 cm/s (p = 0.15)], anterior [− 5.8 ± 3.3 vs. − 4.0 ± 1.7 cm/s (p = 0.17)], and posterior [− 2.3 ± 2.1 vs. − 2.5 ± 1.0 cm/s (p = 0.78)] walls. When observing the myocardial velocity in a single point and visualizing the movement of the main direction of the velocities in this point as vectors in velocity vector plots like planes, it is clear that myocardial movement is by no means one dimensional. In conclusion, our time‐resolved 3D, phase contrast MRI technique makes it feasible to extract myocardial velocities from anywhere in the myocardium, including all three velocity components without the need for positioning any slices at the time of acquisition.
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| 9. |
- Fyrenius, Anna, 1969-, et al.
(författare)
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Major and minor axes of the normal mitral annulus
- 2001
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Ingår i: Journal of Heart Valve Disease. - 0966-8519 .- 2053-2644. ; 10:2, s. 146-152
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Tidskriftsartikel (refereegranskat)abstract
- Background and aim of the study: A dilated or abnormally shaped mitral annulus is a common cause of mitral valve regurgitation, and may be cured by annuloplastic surgery. Multiplane transesophageal echocardiography (TEE) is the diagnostic technique of choice. Our aim was to evaluate and suggest two-dimensional TEE reference values from a standardized procedure of measuring the mitral annular major and minor axes, and their cyclic changes. Methods: The annulus was approximated elliptic in the horizontal plane. The intercommissural (IC, major axis) and anteroposterior (AP, minor axis) distances were measured at end-systole (ES), at maximal valve opening (MO), and at end-diastole (ED) from a mid-esophageal view, in 13 men and eight women with normal echocardiographic findings. Indexed values and reproducibility were calculated. Results: The success rate was 100% at ES, 90% at MO, and 29% at ED. ES distances were largest (p <0.001) and most reproducible (5-5.9%). Body weight, but not height or age, had a significant impact. ES 95% prediction intervals for IC were 27 to 46 mm (16-23 mm/m2) and 22 to 36 mm (13-18 mm/m2) for AP (p <0.001). Corresponding body weight-corrected intervals were 0.39 to 0.59 (IC) and 0.32 to 0.48 (AP) mm/kg. No subject had IC:AP <1.1 together with an AP >0.45 mm/kg. Conclusion: Among measurements made at ES, MO and ED, those at ES provided the most reproducible results, and high-quality images were obtained in normal, non-obese subjects. The distances should be judged in relation to body weight or surface area and each other. The largest IC distance and the most elliptic shape were at ES, while the annulus was minimal at ED. The procedure and normal ranges presented may contribute to the evaluation of patients with mitral regurgitation.
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| 10. |
- Fyrenius, Anna, et al.
(författare)
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Three-dimensional flow in the human left atrium
- 2001
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Ingår i: Heart. - : BMJ. - 1355-6037 .- 0007-0769. ; 86:4, s. 448-455
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Abnormal flow patterns in the left atrium in atrial fibrillation or mitral stenosis are associated with an increased risk of thrombosis and systemic embolisation; the characteristics of normal atrial flow that avoid stasis have not been well defined. OBJECTIVES: To present a three dimensional particle trace visualisation of normal left atrial flow in vivo, constructed from flow velocities in three dimensional space. METHODS: Particle trace visualisation of time resolved three dimensional magnetic resonance imaging velocity measurements was used to provide a display of intracardiac flow without the limitations of angle sensitivity or restriction to imaging planes. Global flow patterns of the left atrium were studied in 11 healthy volunteers. RESULTS: In all subjects vortical flow was observed in the atrium during systole and diastolic diastasis (mean (SD) duration of systolic vortex, 280 (77) ms; and of diastolic vortex, 256 (118) ms). The volume incorporated and recirculated within the vortices originated predominantly from the left pulmonary veins. Inflow from the right veins passed along the vortex periphery, constrained between the vortex and the atrial wall. CONCLUSIONS: Global left atrial flow in the normal human heart comprises consistent patterns specific to the phase of the cardiac cycle. Separate paths of left and right pulmonary venous inflow and vortex formation may have beneficial effects in avoiding left atrial stasis in the normal subject in sinus rhythm.
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| 11. |
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| 12. |
- Kotarba, A., et al.
(författare)
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High pressure desorption of K+ from iron ammonia catalyst migration of the promoter towards Fe active planes
- 2004
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Ingår i: Catalysis Letters. ; 95:1-2, s. 93-97
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Tidskriftsartikel (refereegranskat)abstract
- The thermal desorption of potassium ions from industrial iron catalysts was studied in situ in the wide pressure range of 10(-8)-10 bar of Ar, N-2 and synthesis gas mixture of N-2:3H(2). While high activation energy of 284 +/- 1 kJ/mol, for K (+) was determined for the catalyst precursor, in the reaction conditions it drops down to 231 +/- 5 kJ/mol, corresponding well to that found for iron single crystals in UHV studies. The results are rationalized in terms of potassium migration from oxide storage phases towards the iron facets developed during the catalyst activation.
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| 15. |
- Madler, C.F., et al.
(författare)
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Non-invasive diagnosis of coronary artery disease by quantitative stress echocardiography : Optimal diagnostic models using off-line tissue Doppler in the MYDISE study
- 2003
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Ingår i: European Heart Journal. - 0195-668X .- 1522-9645. ; 24:17, s. 1584-1594
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To develop optimal methods for the objective non-invasive diagnosis of coronary artery disease, using myocardial Doppler velocities during dobutamine stress echocardiography. Methods and results: We acquired tissue Doppler digital data during dobutamine stress in 289 subjects, and measured myocardial responses by off-line analysis of 11 left ventricular segments. Diagnostic criteria developed by comparing 92 normal subjects with 48 patients with coronary disease were refined in a prospective series of 149 patients referred with chest pain. Optimal diagnostic accuracy was achieved by logistic regression models, using systolic velocities at maximal stress in 7 myocardial segments, adjusting for independent correlations directly with heart rate and inversely with age and female gender (all p<0.001). Best cut-points from receiveroperator curves diagnosed left anterior descending, circumflex and right coronary disease with sensitivities and specificities of 80% and 80%, 91% and 80%, and 93% and 82%, respectively. All models performed better than velocity cut-offs alone (p<0.001). Conclusion: Non-invasive diagnosis of coronary artery disease by quantitative stress echocardiography is best performed using diagnostic models based on segmental velocities at peak stress and adjusting for heart rate, and gender or age. © 2003 Published by Elsevier Ltd on behalf of The European Society of Cardiology.
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| 16. |
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| 17. |
- Thunberg, Per, 1968-, et al.
(författare)
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Correction for acceleration-induced displacement artifacts in phase contrast imaging
- 2000
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Ingår i: Magnetic Resonance in Medicine. - New York, USA : John Wiley & Sons. - 0740-3194 .- 1522-2594. ; 43:5, s. 734-738
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Tidskriftsartikel (refereegranskat)abstract
- The acceleration-induced displacement artifact impairs the accuracy of MR velocity measurements. This study proposes a post processing method for correction of this artifact. Velocity measurements were performed in a flow phantom containing a constriction. Velocity curves were obtained from streamlines parallel to the frequency, phase, and slice directions, respectively. The acceleration-induced displacement artifact was most prominent when the frequency encoding direction was aligned with the flow direction. After correction, velocity assignment improved and a more accurate description of the flow was obtained. In vivo measurements were performed in the aorta in a patient with a repaired aortic coarctation. The correction method was applied to velocity data along a streamline parallel to the frequency encoding direction. The result after correction was a new location of the peak velocity and improved estimates of the velocity gradients.
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| 18. |
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