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- Kraus, Stefan, et al.
(författare)
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Planet Formation Imager (PFI) : Science vision and key requirements
- 2016
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Ingår i: Optical and Infrared Interferometry and Imaging V. - : SPIE. - 9781510601932 ; 9907
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Konferensbidrag (refereegranskat)abstract
- The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to ∼100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs.
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| 4. |
- Ding, Wen-Hong, et al.
(författare)
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Early and long-term survival after aortic valve replacement in septuagenarians and octogenarians with severe aortic stenosis.
- 2010
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Ingår i: International Journal of Cardiology. - : Elsevier. - 0167-5273 .- 1874-1754. ; 141:1, s. 24-31
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the predictors for mortality following aortic valve replacement (AVR) in elderly patients with aortic stenosis (AS).METHODS: 112 consecutive elderly AS patients (aged 77+/-2 years) with AVR between 1998 and 2003 were studied. Clinical and echocardiographic data of LV function were recorded before and 46 months after AVR. Results were compared with 72 younger patients (aged 60+/-1 years). Outcome measures were 30-day and long-term all cause mortalities.RESULTS: Elderly patients had higher NYHA class, more frequent atrial fibrillation, coronary artery disease, emergency operation and use of bioprosthetic valves. They also had shorter E-wave deceleration time (DT) and larger left atria (p<0.05 for all). 30-day mortality was 12% vs 4% (Log Rank x(2)=3.02, p=0.08) and long term mortality was 18% vs 7% (Log Rank x(2)=4.38, p=0.04) in two groups respectively. Age was not related to mortality after adjustment for other variables. Among all variables, anemia (OR 4.20, CI: 1.02-6.86, p=0.04), cardiopulmonary bypass (CPB) time (OR 1.02, CI 1.01-1.04, p<0.01), significant prosthesis patient mismatch (PPM) (OR 5.43, CI 1.04-18.40, p<0.05) were associated with 30-day mortality in elderly patients. Their long-term mortality was related to CBP time (OR 1.02, CI 1.00-1.05, p=0.04), PPM (OR 4.64, CI 1.33-16.11, p=0.02) and raised left atrial pressure: DT (OR 0.94, CI 0.84-0.99, p=0.03) and pulmonary arterial systolic pressure (OR 1.12, CI 1.03-1.19, p<0.001).CONCLUSION: Peri-operative AVR survival is encouraging. While pre-operative anemia and a longer CBP time determine early mortality, long term mortality is related to PPM, LV diastolic dysfunction and secondary pulmonary hypertension.
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| 5. |
- Ding, Wen-hong, et al.
(författare)
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Echocardiographic predictors of left ventricular functional recovery following valve replacement surgery for severe aortic stenosis.
- 2008
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 128:2, s. 178-84
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We aimed to identify the most sensitive echocardiographic measurements that predict recovery of left ventricular function following valve replacement surgery in patients with severe aortic stenosis (AS) and LV dysfunction.METHODS: We studied 66 patients (mean age 70+/-2 years, 53 male) who underwent AVR for severe AS with concurrent LV dysfunction between 1998 and 2003 at the Royal Brompton Hospital. Clinical symptoms, co-morbidities and echocardiographic measurements of LV function were recorded before and at a median follow-up of 46 months after AVR. Pre-operative LV systolic dysfunction was defined as LV ejection fraction (EF) <50% and the post-op LV recovery as an increase of EF >10%.RESULTS: Following AVR peak aortic pressure gradient decreased and aortic valve area index increased (64+/-3 to 19+/-1 mm Hg and 0.30+/-0.01 to 0.89+/-0.03 cm(2)/m(2), p<0.001 for both). LV EF increased (from 45+/-1 to 54+/-2%; p<0.001) and the LV dimensions fell (LVEDD index: from 33+/-1 to 30+/-1 mm/m(2); and LVESD index: from 27+/-1 to 20+/-1 mm/m(2); p<0.01 for both). LV diastolic dysfunction improved as evidenced by the fall in E/A ratio (from 2.6+/-0.2 to 1.9+/-0.4) and prolongation of total filling time; (from 29.2+/-0.6 to 31.4+/-0.5 s/min, p=0.01 for both). Among all echocardiographic variables, LV dimensions (LVEDD index, OR 0.70, CI 0.52-0.97, p<0.05; LVESD index, OR 0.57, CI 0.40-0.85, p=0.005) were the two independent predictors of post-operative LV functional recovery on multivariate analysis. A cut off value of pre-operative LVESD index=or<27.5 mm/m(2) was 85% sensitive and 72% specific in predicting intermediate-term recovery of LV function after AVR (AUC, 0.72, p=0.002).CONCLUSION: LV functional recovery was evident in majority of aortic stenotic patients with LV dysfunction after aortic valve replacement. A lower prevalence of LV functional recovery in patients with large pre-operative LV end systolic dimension index might signify the loss of contractile reserve and thus predict post-operative functional recovery.
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| 6. |
- Ding, Wen-Hong, et al.
(författare)
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Predictors of survival after aortic valve replacement in patients with low-flow and high-gradient aortic stenosis
- 2009
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Ingår i: European Journal of Heart Failure. - : Oxford University Press. - 1388-9842 .- 1879-0844. ; 11:9, s. 897-902
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To identify predictors of survival following aortic valve replacement (AVR) in patients with low-flow and high-gradient aortic stenosis (AS).METHODS AND RESULTS: Eighty-six patients (aged 71 +/- 10 years) with severe AS [aortic valve mean pressure gradient >40 mmHg or valve area <1.0 cm(2)] and left ventricular (LV) dysfunction [ejection fraction (EF) <50%] underwent AVR. Cox proportional hazards were used to identify independent clinical and echocardiographic predictors of mortality. Operative (30-day) mortality was 10%. Peri-operative mortality was associated with lower mean LVEF, higher mitral E:A ratio, peak systolic pulmonary artery pressure (PSPAP), and serum creatinine (by 12%, 2.3, 28 mmHg, and 74 mmol/L, respectively, all P < 0.001), NYHA class III-IV (100 vs. 65%), concomitant CABG (89 vs. 55%), urgent surgery (78 vs. 35%), and longer bypass-time (by 28 min, all P < 0.05). Mortality at 4 years was 17%. Univariate predictors [hazard ratio (HR)] of 4-year mortality were: lower EF (HR 0.68 per % increase, P < 0.001), presence of restrictive LV filling (HR: 3.52, P < 0.001), raised PSPAP (HR: 1.07, P < 0.001), and CABG (HR: 4.93, P = 0.037). However, only low EF (<40%, HR 0.74, P = 0.030), the presence of restrictive filling (HR 1.77, P = 0.033), and raised PSPAP (>45 mmHg, HR 2.71, P = 0.010) remained as independent predictors after multivariate analysis. CONCLUSION: The severity of pre-operative systolic and diastolic LV dysfunction is the major predictor of mortality following AVR for low-flow and high-gradient AS.
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| 7. |
- Henein, Michael Y., et al.
(författare)
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Aortic valve
- 2012. - 2
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Ingår i: Clinical echocardiography. - London : Springer. - 9781848825215 - 9781848825208 ; , s. 33-62
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Bokkapitel (refereegranskat)abstract
- The aortic valve is a passive valve made up of three leaflets which assume the shape of half moons (semi-lunar). Opposite to the mitral valve, there is no true aortic fibrous annulus but a complex root made up of the aortic wall sinuses, left ventricular myocardium, and interleafletfibrous triangles. The ostia of the coronary arteries are located within the aortic sinuses. The sinotubular junction is an important anatomic landmark for surgical procedures. It may be that the leaflets of the aortic valve are not passive as they are rich in different types of nerve endings. The function and role of these “nerves” remain obscure.
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| 8. |
- Henein, Michael Y., et al.
(författare)
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Coronary artery disease
- 2012. - 2
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Ingår i: Clinical echocardiography. - London : Springer. - 9781848825215 - 9781848825208 ; , s. 115-147
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Bokkapitel (refereegranskat)abstract
- Anomalous origin of the left coronary artery from the pulmonary trunk usually presents in early infancy with congestive cardiac failure due to ischemic myocardial dysfunction. The diagnosis can usually be made by parasternal short axis sections of the great arteries. The most characteristic finding is reversed flow in the left coronary artery demonstrated by color flow Doppler. Usually the anomalous coronary artery connects to the pulmonary trunk at one of the sinuses, but in some cases the connection may be to the more distal pulmonary arteries. A less common presentation of this condition is in late childhood or early adult life, usually with left ventricular dysfunction and mitral regurgitation. There is almost always reversed blood flow in the left coronary artery representing a left to right shunt from the right coronary artery into the pulmonary trunk.
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| 9. |
- Henein, Michael Y., et al.
(författare)
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Dilated cardiomyopathy
- 2012. - 2
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Ingår i: Clinical echocardiography. - London : Springer. - 9781848825215 - 9781848825208 ; , s. 167-185
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Bokkapitel (refereegranskat)abstract
- Dilated cardiomyopathy is characterized by left ventricular dilatation, increased end diastolic volume, and reduced systolic function (typically ejection fraction less than 40%) [1, 2].
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| 10. |
- Henein, Michael Y., et al.
(författare)
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Diseases of the aorta
- 2012. - 2
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Ingår i: Clinical echocardiography. - London : Springer. - 9781848825215 - 9781848825208 ; , s. 225-237
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Bokkapitel (refereegranskat)abstract
- Acute aortic dissection is a surgical emergency that requires accurate diagnosis and prompt management. A number of classifications exist, the simplest of which classifies aortic dissection according to the location of the entry point into: type “A” which involves all forms that include the ascending aorta and type “B” which does not involve the ascending aorta. While type “A” is always an emergency diagnosis and management, type “B” can be managed medically or conservatively. Mortality from type “A” dissection may be up to 60% within the first 24 h, 80% over the first 2 weeks and 90% within 3 months of acute attack. Dissection of the proximal ascending aorta can often be seen on transthoracic echo imaging, and even those involving the distal ascending aorta may occasionally be detected.
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