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- Bech-Hanssen, O, et al.
(författare)
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Aortic prosthetic valve design and size : Relation to Doppler echocardiographic findings and pressure recovery - An in vitro study
- 2000
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Ingår i: Journal of the American Society of Echocardiography. - 0894-7317 .- 1097-6795. ; 13:1, s. 39-50
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Tidskriftsartikel (refereegranskat)abstract
- The extent to which Doppler echocardiography information can be used in the assessment of prosthesis hemodynamic performance is still controversial. The goals of our study were to assess the importance of valve design and size both on Doppler echocardiography findings and on pressure recovery in a fluid mechanics model. We performed Doppler and catheter measurements in the different orifices of the bileaflet St Jude (central and side orifices), the monoleaflet Omnicarbon (major and minor orifices), and the stented Biocor porcine prosthesis. Net pressure gradients were predicted from Doppler flow velocities, assuming either independence or dependence of valve size. The peak Doppler estimated gradients (mean +/- SD for sizes 21 to 27) were 21 +/- 10.3 rum Hg for St Jude, 18 +/- 9.3 mm Hg for Omnicarbon, and 37 +/- 14.5 mm Hg for Biocor (P <.05 for St Jude and Omnicarbon vs Biocor). The pressure recovery (proportion of peak catheter pressure) was 53% +/- 8.6% for central-St Jude, 29% +/- 8.9% for side-St Jude, 20% +/- 5.6% for major-Omnicarbon, 23% +/- 7.4% for minor-Omnicarbon, and 18% +/- 3.6% for Biocor (P <.05 for central-St Jude and side-St Jude vs Omnicarbon and Biocor). Valve sizes (2) significantly influenced pressure recovery (y in percentage) (central-St Jude: y = 3.7x - 35.9, r = 0.88, P =.0001, major-Omnicarbon: y = 2.1x - 30.3, r = 0.85, P =.0001). By assuming dependence of valve size, Doppler was able to predict net pressure gradients in St Jude with a mean difference between net catheter and Doppler-predicted gradient of - 3.8 +/- 2.5 mm Hg. In conclusion, prosthetic value design and size influence the degree of pressure recovery, making Doppler gradients potentially misleading in both the assessment of hemodynamic performance and the comparison of one design with another. The preliminary results indicate that net gradient can be predicted from Doppler gradients,
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| 2. |
- Bech-Hanssen, O., et al.
(författare)
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Net Pressure Gradients in Aortic Prosthetic Valves can be Estimated by Doppler
- 2003
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Ingår i: Journal of the American Society of Echocardiography. - 0894-7317 .- 1097-6795. ; 16:8, s. 858-866
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Tidskriftsartikel (refereegranskat)abstract
- Background: In aortic prosthetic valves, both the Doppler-estimated gradients and orifice areas are misleading in the assessment of hemodynamic performance. The parameter of major interest is the net pressure gradient after pressure recovery (PR). We, therefore, investigated, in vitro, our ability to predict the net pressure gradient and applied the formulas in a representative patient population with 2 different valve designs. Methods: We studied the St Jude Medical (SJM) standard valve (size 19-27) and SJM Biocor (size 21-27) in an in vitro steady-flow model with simultaneous Doppler-estimated pressure and catheter pressure measurements. Using echocardiography, we also studied patients who received the SJM (n = 66) and SJM Biocor (n = 45). Results: In the SJM, we observed PR both within the prosthesis and aorta, whereas in the SJM Biocor, PR was only present in the aorta. We estimated the PR within the valve and within the aorta separately from echocardiographic in vitro data, combining a regression equation (valve) with an equation on the basis of fluid mechanics theory (aorta). The difference between estimated and catheter-obtained net gradients (mean ± SD) was 0.6 ± 1.6 mm Hg in the SJM and - 0.2 ± 1.9 mm Hg in the SJM Biocor. When these equations were applied in vivo, we found that PR had an overall value of 57 ± 7% of the peak Doppler gradient in the SJM and 33 ± 9% in the SJM Biocor. Conclusions: The in vitro results indicate that it is possible to predict the net pressure gradient by Doppler in bileaflet and stented biologic valves. Our data indicate that important PR is also present in stented biologic valves.
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| 3. |
- Maleki, Shohreh, et al.
(författare)
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Identification of a novel flow-mediated gene expression signature in patients with bicuspid aortic valve
- 2013
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Ingår i: Journal of Molecular Medicine. - : Springer-Verlag New York. - 0946-2716 .- 1432-1440. ; 91:1, s. 129-139
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Individuals with bicuspid aortic valve (BAV) are at significantly higher risk of developing serious aortic complications including aortic aneurysm and dissection than individuals with a tricuspid aortic valve (TAV). Studies have indicated an altered aortic blood flow in patients with BAV, however the extent to which altered flow may influence the pathological state of BAV aorta is still unclear.Objective: To dissect flow-mediated gene expression potentially leading to increased aneurysm susceptibility in patients with BAV.Methods and Results: A large collection of publically available microarray data sets were screened for consistent co-expression with KLF2, KLF4, TIE1, THBD, and PKD2, five previously well-characterized flow-regulated genes. This identified 122 genes with coexpression probability of >0.5. Of these, 44 genes satisfied two additional filtering criteria in ascending aorta (127 arrays). The criteria were significant correlation with one or more of the 5 query genes (R>0.40) and differential expression between patients with BAV and TAV. No gene fulfilled the criteria in mammary artery (88 arrays). A large proportion of the identified genes were angiogenesis related genes. Further, 55% of the genes differentially expressed between BAV and TAV showed differential expression in disturbed vs. uniform flow pattern regions in rat aorta. Protein expression of ZFP36, PKD2 and GPR116 were analyzed by immunohistochemistry and their association with BAV were further discussed.Conclusions: With a new strategy to dissect flow-mediated gene expression, we identified novel genes associated with valve morphology. The complex pattern of blood flow, as a consequence of BAV
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| 4. |
- Torén, Kjell, 1952, et al.
(författare)
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Chronic airflow limitation and its relation to respiratory symptoms among ever-smokers and never-smokers: a cross-sectional study
- 2020
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Ingår i: Bmj Open Respiratory Research. - : BMJ. - 2052-4439. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Background The diagnosis of chronic obstructive pulmonary disease is based on the presence of persistent respiratory symptoms and chronic airflow limitation (CAL). CAL is based on the ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1:FVC) after bronchodilation, and FEV1:FVC less than the fifth percentile is often used as a cut-off for CAL. The aim was to investigate if increasing percentiles of FEV1:FVC were associated withany respiratory symptom(cough with phlegm, dyspnoea or wheezing) in a general population sample of never-smokers and ever-smokers. Methods In a cross-sectional study comprising 15 128 adults (50-64 years), 7120 never-smokers and 8008 ever-smokers completed a respiratory questionnaire and performed FEV(1)and FVC after bronchodilation. We calculated theirz-scores for FEV1:FVC and defined the fifth percentile using the Global Lung Function Initiative (GLI) reference value, GLI(5)and increasing percentiles up to GLI(25). We analysed the associations between different strata of percentiles and prevalence ofany respiratory symptomusing multivariable logistic regression for estimation of OR. Results Among all subjects, regardless of smoking habits, the odds ofany respiratory symptomwere elevated up to the GLI(15-20)strata. Among never-smokers, the odds ofany respiratory symptomwere elevated at GLI(<5)(OR 3.57, 95% CI 2.43 to 5.23) and at GLI(5-10)(OR 2.57, 95% CI 1.69 to 3.91), but not at higher percentiles. Among ever-smokers, the odds ofany respiratory symptomwere elevated from GLI(<5)(OR 4.64, 95% CI 3.79 to 5.68) up to GLI(>= 25)(OR 1.33, 95% CI 1.00 to 1.75). Conclusions The association between percentages of FEV1:FVC and respiratory symptoms differed depending on smoking history. Our results support a higher percentile cut-off for FEV1:FVC for never-smokers and, in particular, for ever-smokers.
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| 5. |
- Torén, Kjell, 1952, et al.
(författare)
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The ratio FEV1/FVC and its association to respiratory symptoms-A Swedish general population study
- 2021
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 41:2, s. 181-191
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Tidskriftsartikel (refereegranskat)abstract
- Chronic airflow limitation (CAL) can be defined as fixed ratio of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) any respiratory symptom. In a cross-sectional general population study, 15,128 adults (50-64 years of age), 7,120 never-smokers and 8,008 ever-smokers completed a respiratory questionnaire and performed FEV1 and FVC after bronchodilation. We calculated different ratios of FEV1/FVC from 0.40 to 1.0 using 0.70 as reference category. We analysed odds ratios (OR) between different ratios and any respiratory symptom using adjusted multivariable logistic regression. Among all subjects, regardless of smoking habits, the lowest odds for any respiratory symptom was at FEV1/FVC = 0.82, OR 0.48 (95% CI 0.41-0.56). Among never-smokers, the lowest odds for any respiratory symptom was at FEV1/FVC = 0.81, OR 0.53 (95% CI 0.41-0.70). Among ever-smokers, the odds for any respiratory symptom was lowest at FEV1/FVC = 0.81, OR 0.43 (95% CI 0.16-1.19), although the rate of inclining in odds was small in the upper part, that is FEV1/FVC = 0.85 showed similar odds, OR 0.45 (95% CI 0.38-0.55). We concluded that the odds for any respiratory symptoms continuously decreased with higher FEV1/FVC ratios and reached a minimum around 0.80-0.85, with similar results among never-smokers. These results indicate that the optimal threshold associated with respiratory symptoms may be higher than 0.70 and this should be further investigated in prospective longitudinal studies.
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