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1.
Arch Cardiovasc Dis ; 117(4): 266-274, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38423888

ABSTRACT

BACKGROUND: New-onset atrial fibrillation (NOAF) is a well-known complication of ST-segment elevation myocardial infarction (STEMI), probably due to left atrial (LA) remodelling. LA strain (LAS) can predict NOAF in several cardiovascular diseases. OBJECTIVE: To assess whether LAS predicts NOAF in sinus rhythm patients with STEMI during hospitalization. METHODS: Adults with a STEMI and transthoracic echocardiography performed within 48hours of admission were included. LAS analysis, performed by automated software, recorded LAS during the reservoir phase (LASr), the conduit phase (LAScd) and the contraction phase (LASct). RESULTS: From May 2021 to November 2022, 175 patients were included, 21 (12%) of whom developed NOAF. NOAF patients were older (median [Q1-Q3]: 67 [59-80] vs 59 [51-67]years; P=0.006) and had a higher Thrombolysis In Myocardial Infarction scores (4 [2-7] vs 3 [1-4]; P=0.005). All LAS parameters were significantly impaired in NOAF patients, especially LASr (13.0% [10.5-28.4] vs 36.6% [29.0-44.9]; P=0.001). An LASr cut-off of 27% had a sensitivity of 81% and a specificity of 80% to identify patients with NOAF. In a multivariable model, LASr was significantly associated with NOAF (odds ratio 1.18, 95% confidence interval 1.09-1.26; P=0.003). The cumulative risk of NOAF during hospital stay was 30% (18-43 with LASr<27% and 4% [1.5-8.5] with LASr≥27% [P<0.0001]). CONCLUSION: NOAF is a frequent complication of STEMI. LASr seems helpful for identifying patients at high risk of NOAF during hospitalization.


Subject(s)
Atrial Fibrillation , Myocardial Infarction , ST Elevation Myocardial Infarction , Adult , Humans , ST Elevation Myocardial Infarction/diagnostic imaging , ST Elevation Myocardial Infarction/therapy , ST Elevation Myocardial Infarction/complications , Prospective Studies , Atrial Fibrillation/diagnostic imaging , Atrial Fibrillation/therapy , Myocardial Infarction/complications , Echocardiography
2.
J Clin Med ; 13(4)2024 Feb 09.
Article in English | MEDLINE | ID: mdl-38398319

ABSTRACT

Introduction: Right-ventricular-to-pulmonary artery (RV-PA) coupling, measured as the ratio of tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure (PASP), has emerged as a predictor factor in patients undergoing transcatheter aortic valvular replacement (TAVR). Right ventricular longitudinal shortening fraction (RV-LSF) outperformed TAPSE as a prognostic parameter in several diseases. We aimed to compare the prognostic ability of two RV-PA coupling parameters (TAPSE/PASP and the RV-LSF/PASP ratio) in identifying MACE occurrences. Method: A prospective and single-center study involving 197 patients who underwent TAVR was conducted. MACE (heart failure, myocardial infarction, stroke, and death within six months) constituted the primary outcome. ROC curve analysis determined cutoff values for RV-PA ratios. Multivariable Cox regression analysis explored the association between RV-PA ratios and MACE. Results: Forty-six patients (23%) experienced the primary outcome. No significant difference in ROC curve analysis was found (RV-LSF/PASP with AUC = 0.67, 95%CI = [0.58-0.77] vs. TAPSE/PASP with AUC = 0.62, 95%CI = [0.49-0.69]; p = 0.16). RV-LSF/PASP < 0.30%.mmHg-1 was independently associated with the primary outcome. The 6-month cumulative risk of MACE was 59% (95%CI = [38-74]) for patients with RV-LSF/PASP < 0.30%.mmHg-1 and 17% (95%CI = [12-23]) for those with RV-LSF/PASP ≥ 0.30%.mmHg-1; (p < 0.0001). Conclusions: In a contemporary cohort of patients undergoing TAVR, RV-PA uncoupling defined by an RV-LSF/PASP < 0.30%.mmHg-1 was associated with MACE at 6 months.

3.
Am J Cardiol ; 211: 79-88, 2024 Jan 15.
Article in English | MEDLINE | ID: mdl-37898222

ABSTRACT

Right ventricular systolic dysfunction (RVsD) frequently occurs in patients with ST-elevation myocardial infarction (STEMI). However, the diagnosis depends on the echocardiographic parameters to define RVsD. The right ventricle longitudinal shortening fraction (RV-LSF) is an accurate and reproducible 2-dimensional speckle-tracking parameter associated with clinical events in various pathologies. This study aimed to evaluate the association between RVsD and major adverse cardiovascular event (MACE) occurrence in a cohort of patients with STEMI. Adult patients with STEMI admitted to Amiens University Hospital's cardiovascular intensive care unit between May 2021 and November 2022 who underwent coronary angiography and transthoracic echocardiography within 48 hours of admission were included. RVsD was defined as RV-LSF <20%. The primary outcome was MACE occurrence, including heart failure, myocardial infarction, stroke, and death within 6 months of admission. A multivariable Cox regression analysis with proportional hazard ratio models assessed the association between RVsD and MACEs. In the 164 included patients, 72 (44%) had RVsD and 92 (56%) did not. The RVsD group had a significantly higher proportion of MACEs during the 6-month follow-up (n = 23 of 72, 33%) than the group without RVsD (n = 8 of 92, 9%, p = 0.001). RVsD showed an independent association with MACEs at 6 months (hazard ratio 3.1, 95% confidence interval [CI] 1.35 to 7.30, p = 0.008). Left ventricular ejection fraction <40% and Thrombolysis in Myocardial Infarction score >4 were independently associated with RVsD (odds ratio 2.80, 95% CI 1.34 to 5.98 and odds ratio 2.15, 95% CI 1.18 to 4.39, respectively, p = 0.015). The cumulative risk of MACEs at 6 months was 33% for RV-LSF <20% and 9% for RV-LSF ≥20% (log-rank test p <0.001). RVsD, defined by RV-LSF <20%, is associated with an increased risk of MACEs after STEMI.


Subject(s)
Myocardial Infarction , Percutaneous Coronary Intervention , ST Elevation Myocardial Infarction , Adult , Humans , Prognosis , ST Elevation Myocardial Infarction/complications , Stroke Volume , Heart Ventricles/diagnostic imaging , Prospective Studies , Ventricular Function, Left , Echocardiography/methods , Myocardial Infarction/complications , Percutaneous Coronary Intervention/adverse effects
4.
Arch Cardiovasc Dis ; 116(5): 240-248, 2023 May.
Article in English | MEDLINE | ID: mdl-37032221

ABSTRACT

BACKGROUND: The first wave of the coronavirus disease 2019 pandemic significantly changed behaviour in terms of access to healthcare. AIM: To assess the effects of the pandemic and initial lockdown on the incidence of acute coronary syndrome and its long-term prognosis. METHODS: Patients admitted for acute coronary syndrome from 17 March to 6 July 2020 and from 17 March to 6 July 2019 were included. The number of admissions for acute coronary syndrome, acute complication rates and 2-year rates of survival free from major adverse cardiovascular events or death from any cause were compared according to the period of hospitalization. RESULTS: In total, 289 patients were included. We observed a 30±3% drop in acute coronary syndrome admissions during the first lockdown, which did not recover in the 2months after it was lifted. At 2years, there were no significant differences in the combined endpoint of major adverse cardiovascular events or death from any cause between the different periods (P=0.34). Being hospitalized during lockdown was not predictive of adverse events during follow-up (hazard ratio 0.87, 95% confidence interval 0.45-1.66; P=0.67). CONCLUSIONS: We did not observe an increased risk of major cardiovascular events or death at 2years from initial hospitalization for patients hospitalized during the first lockdown, adopted in March 2020 in response to the coronavirus disease 2019 pandemic, potentially as a result of the lack of power of the study.


Subject(s)
Acute Coronary Syndrome , COVID-19 , Humans , COVID-19/epidemiology , Acute Coronary Syndrome/diagnosis , Acute Coronary Syndrome/epidemiology , Acute Coronary Syndrome/therapy , Pandemics , Communicable Disease Control , Prognosis
5.
J Wrist Surg ; 11(3): 262-268, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35837588

ABSTRACT

Background Isolated scaphotrapeziotrapezoid (STT) osteoarthritis (OA) mainly develops in women over 50 years of age in a bilateral manner. Many surgical treatments are available, including distal scaphoid resection with or without interposition, trapeziectomy, and STT arthrodesis. However, there is a controversy about which procedure is the most effective. Purposes The purpose of this study was to report the outcomes of the Pyrocardan implant for treating STT isolated OA at a mean follow-up of 5 years. Patients and Methods Consecutive patients who underwent STT arthroplasty using the Pyrocardan were reviewed retrospectively by an independent examiner who performed a clinical and radiological evaluation. Results The mean follow-up time was 5 years (range 3-8 years). Thirteen patients (76%) were followed for more than 5 years. Between the preoperative assessment and the last follow-up, pain levels decreased significantly. There was no significant difference in the mean Kapandji opposition score. Grip and pinch strengths were 88 and 91% of the contralateral side. The active range of motion in flexion-extension and radioulnar deviation was not significantly different to the contralateral side (119° vs. 121° and 58° vs. 52°, p > 0.1). Functional scores were improved significantly. No identifiable differences were found in the radioscaphoid, capitolunate, and scapholunate angles before and after surgery. In three cases, the preoperative dorsal intercalated scapholunate instability (DISI) failed to be corrected. In one case, DISI appeared after the procedure. There was one asymptomatic dislocation of the implant. Calcification around the trapezium and/or distal scaphoid was found in four cases. The survival rate of the implant without reoperation was 95%. Conclusions In the medium term, Pyrocardan implant is an effective treatment for STT OA as it reduces pain, increases grip strength, and maintains wrist mobility. This is consistent with the results of other published case series using pyrocarbon implants. It provides a high rate of patient satisfaction. Nevertheless, the surgical procedure must be done carefully to avoid STT ligament damage, periarticular calcifications, or dislocation.

6.
Lancet Reg Health Eur ; 2: 100030, 2021 Mar.
Article in English | MEDLINE | ID: mdl-34173627

ABSTRACT

BACKGROUND: A reduction of admission for MI has been reported in most countries affected by COVID-19. No clear explanation has been provided. METHODS: To report the incidence of myocardial infarction (MI) admission during COVID-19 pandemic and in particular during national lockdown in two unequally affected French provinces (10-million inhabitants) with a different media strategy, and to describe the magnitude of MI incidence changes relative to the incidence of COVID-19-related deaths. A longitudinal study to collect all MIs from January 1 until May 17, 2020 (study period) and from the identical time period in 2019 (control period) was conducted in all centers with PCI-facilities in northern "Hauts-de-France" province and western "Pays-de-la-Loire" Province. The incidence of COVID-19 fatalities was also collected. FINDINGS: In "Hauts-de-France", during lockdown (March 18-May 10), 1500 COVID-19-related deaths were observed. A 23% decrease in MI-IR (IRR=0.77;95%CI:0.71-0.84, p<0.001) was observed for a loss of 272 MIs (95%CI:-363,-181), representing 18% of COVID-19-related deaths. In "Pays-de-la-Loire", 382 COVID-19-related deaths were observed. A 19% decrease in MI-IR (IRR=0.81; 95%CI=0.73-0.90, p<0.001) was observed for a loss of 138 MIs (95%CI:-210,-66), representing 36% of COVID-19-related deaths. While in "Hauts-de-France" the MI decline started before lockdown and recovered 3 weeks before its end, in "Pays-de-la-Loire", it started after lockdown and recovered only by its end. In-hospital mortality of MI patients was increased during lockdown in both provinces (5.0% vs 3.4%, p=0.02). INTERPRETATION: It highlights one of the potential collateral damages of COVID-19 outbreak on cardiovascular health with a dramatic reduction of MI incidence. It advocates for a careful and weighted communication strategy in pandemic crises. FUNDING: The study was conducted without external funding.

7.
Echocardiography ; 37(6): 883-890, 2020 06.
Article in English | MEDLINE | ID: mdl-32449845

ABSTRACT

BACKGROUND: Dilatation of the ascending aorta has an important role in the anatomical conformation of interatrial septum (IAS) especially when a patent foramen ovale (PFO) is present. The aim of the study was to investigate the relationship between ascending aortic dilation and PFO-related cryptogenic stroke in a cohort of cryptogenic strokes. METHODS: It is a retrospective, single-center echocardiographic study assessing aortic root dilatation in 315 consecutive patients with cryptogenic stroke between January 2011 and January 2019. Aortic root dilatation was defined by a diameter of the Valsalva sinuses of the proximal aorta >40 mm. Predictive factors of PFO were assessed by a multivariate analysis. Propensity score matching was applied to account for clinical differences. RESULTS: Of the 315 patients, 68 (22%) had an aortic root dilatation and 167 (53%) had a PFO. In the aortic root dilation group, PFO was more often diagnosed (n = 47/68 [69%], vs n = 120/247 [49%], P = .004). In the PFO group with aortic dilatation, IAS was more mobile (n = 37/47[79%] vs n = 69/120[57%], P < .012) and smaller (2.3 ± 0.5 vs 2.5 ± 0.5 mm, P < .009). On multivariate analysis, aortic root dilatation (OR: 2.6; 95% CI [1.2-5.6]; P = .001) and IAS hypermobility (OR: 5.2 95% CI [2.7-10]; P = .001) were associated with PFO. After propensity matching, aortic root dilatation remained strongly associated with PFO (n = 34/107 [32%] vs 15/107[14%], P = .002). CONCLUSION: Aortic root dilation and IAS hypermobility were strongly associated with PFO-related cryptogenic stroke.


Subject(s)
Foramen Ovale, Patent , Ischemic Stroke , Stroke , Dilatation , Foramen Ovale, Patent/complications , Foramen Ovale, Patent/diagnostic imaging , Humans , Propensity Score , Retrospective Studies , Risk Factors , Stroke/complications
8.
Eur J Orthop Surg Traumatol ; 26(6): 581-6, 2016 Aug.
Article in English | MEDLINE | ID: mdl-27394685

ABSTRACT

BACKGROUND: The prevalence of combined humeral and glenoid defects varies between 79 and 84 % in case of chronic posttraumatic anterior shoulder instability. The main goal of this study was to evaluate the relationship between humeral and glenoid defects based on quantitative radiological criteria. METHODS: A retrospective study was performed between 2000 and 2011 including patients who underwent primary surgical shoulder stabilization for chronic posttraumatic anterior shoulder instability, with bone defects in both the glenoid and humerus and a healthy contralateral shoulder. The following measurements were taken: D/R ratio (Hill-Sachs lesion depth/humeral head radius) on an AP X-ray in internal rotation and the D1/D2 ratio [diameter of the involved glenoid articular surfaces (D1)/the healthy one (D2)] on a comparative Bernageau glenoid profile view. Measurements were taken by two observers. Correlations were determined by the Spearman correlation coefficients (r), Bland and Altman diagrams, and intra-class correlation coefficients (ICC). A sample size calculation was done. RESULTS: Thirty patients were included, 25 men/5 women, mean age 29.8 ± 11.2 years. The mean D/R was 23 ± 12 % for observer 1 and 23 ± 10 % for observer 2. The mean D1/D2 was 95 ± 4 % for observer 1 and 94 ± 6 % for observer 2. No significant correlation was found between humeral and glenoid bone defects by observer 1 (r = 0.23, p = 0.22) or observer 2 (r = 0.05, p = 0.78). Agreement of the observers for the D/R ratio was excellent (ICC = 0.89 ± 0.04, p < 0.00001) and good for the D1/D2 ratio (ICC = 0.54 ± 0.14, p = 0.006). CONCLUSION: Humeral and glenoid bone defects were not correlated. Inter-observer reliability was excellent for the D/R ratio and good for the D1/D2 ratio. LEVEL OF EVIDENCE: Nonconsecutive Patients, Diagnostic Study, Level III.


Subject(s)
Arthrodesis , Humerus , Scapula , Shoulder Dislocation , Shoulder Joint , Adult , Arthrodesis/adverse effects , Arthrodesis/methods , Female , France/epidemiology , Humans , Humerus/diagnostic imaging , Humerus/pathology , Joint Instability/diagnosis , Joint Instability/etiology , Male , Outcome and Process Assessment, Health Care , Prevalence , Radiography/methods , Retrospective Studies , Scapula/diagnostic imaging , Scapula/pathology , Shoulder Dislocation/diagnosis , Shoulder Dislocation/epidemiology , Shoulder Dislocation/etiology , Shoulder Dislocation/physiopathology , Shoulder Injuries , Shoulder Joint/physiopathology , Shoulder Joint/surgery , Statistics as Topic
9.
Rev Geophys ; 54(2): 410-446, 2016 Jun.
Article in English | MEDLINE | ID: mdl-31423490

ABSTRACT

Polarity reversals of the geomagnetic field are a major feature of the Earth's dynamo. Questions remain regarding the dynamical processes that give rise to reversals and the properties of the geomagnetic field during a polarity transition. A large number of paleomagnetic reversal records have been acquired during the past 50 years in order to better constrain the structure and geometry of the transitional field. In addition, over the past two decades, numerical dynamo simulations have also provided insights into the reversal mechanism. Yet despite the large paleomagnetic database, controversial interpretations of records of the transitional field persist; they result from two characteristics inherent to all reversals, both of which are detrimental to an ambiguous analysis. On the one hand, the reversal process is rapid and requires adequate temporal resolution. On the other hand, weak field intensities during a reversal can affect the fidelity of magnetic recording in sedimentary records. This paper is aimed at reviewing critically the main reversal features derived from paleomagnetic records and at analyzing some of these features in light of numerical simulations. We discuss in detail the fidelity of the signal extracted from paleomagnetic records and pay special attention to their resolution with respect to the timing and mechanisms involved in the magnetization process. Records from marine sediments dominate the database. They give rise to transitional field models that often lead to overinterpret the data. Consequently, we attempt to separate robust results (and their subsequent interpretations) from those that do not stand on a strong observational footing. Finally, we discuss new avenues that should favor progress to better characterize and understand transitional field behavior.

10.
Circ Cardiovasc Imaging ; 8(9): e003036, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26338875

ABSTRACT

BACKGROUND: To prevent left ventricular dysfunction (LVD), surgery is recommended in patients with severe primary mitral regurgitation as soon as ejection fraction (EF) ≤60% or LV end-systolic diameter ≥40 mm. However, LVD may be concealed behind preoperative normal LVEF and LV end-systolic diameter. We sought to identify whether a new composite echocardiographic Doppler marker of the LV ejection according to the LV dilatation may predict postoperative LVD and outcome after mitral valve repair in patients with primary mitral regurgitation. METHODS AND RESULTS: Between 1991 and 2010, patients who underwent mitral valve repair for primary mitral regurgitation were studied. From preoperative echocardiography, we calculated LV ejection index (LVEI) using following formula: LVEI=indexed LV end-systolic diameter/LV outflow tract time-velocity integral. In the 278 patients included, the best correlation with postoperative LVEF was found with LVEI (r=-0.40; P<0.0001), even in patients with preoperative LVEF≥60% (r=-0.46; P<0.0001). In multivariable analysis, LCEI>1.13 was an independent predictor of postoperative LVD (P<0.0001). During a mean follow-up of 10±4.6 years, 67 (29%) deaths occurred. When compared with patients with preserved LVEI, those with LVEI>1.13 had significantly lower both survival and cardiac death-free survival (P=0.017 and P=0.008, respectively). Similar results were found in patients with preoperative LVEF≥60% (P=0.049 and P=0.016, respectively). In Cox proportional hazard model, after meticulous adjustment for cofactors, LVEI>1.13 remains independently associated with death (hazard ratio, 1.64; P=0.039) and cardiac-related death (hazard ratio, 3.27; P=0.026). CONCLUSIONS: After mitral valve repair for primary mitral regurgitation, the preoperative LVEI is a new and simple composite parameter of both LV dilatation and LV forward flow able to accurately predict postoperative LVD and outcome.


Subject(s)
Echocardiography, Doppler/methods , Mitral Valve Insufficiency/physiopathology , Mitral Valve Prolapse/physiopathology , Ventricular Function, Left/physiology , Aged , Female , Follow-Up Studies , Heart Valve Prosthesis , Humans , Male , Mitral Valve Insufficiency/diagnostic imaging , Mitral Valve Insufficiency/etiology , Mitral Valve Prolapse/complications , Mitral Valve Prolapse/diagnostic imaging , Postoperative Period , Prognosis , Retrospective Studies , Risk Factors
11.
Am J Cardiol ; 115(10): 1448-53, 2015 May 15.
Article in English | MEDLINE | ID: mdl-25784520

ABSTRACT

The aim of the study was to assess the impact of atrial fibrillation (AF) on outcome in patients who underwent mitral valve repair (MVRp) for mitral valve prolapse (MVP). Four hundred and forty-three consecutive patients underwent MVRp for organic mitral regurgitation due to MVP. Echocardiography was performed preoperatively and after surgery. Postoperative left ventricular dysfunction (LVD) was defined as left ventricular ejection fraction (LVEF) <50%. Before surgery, 187 patients (42%) had preoperative AF. After surgery, LVEF significantly decreased from 67 ± 9% to 56 ± 10% (p <0.0001). Compared with patients in sinus rhythm (SR), those in AF were significantly older (p <0.0001), had more severe symptoms (p = 0.004), had lower LVEF (p = 0.002), and higher EuroSCORE (p = 0.05). Compared with patients in SR, patients with AF had significantly lower 10-year survival (64 ± 4% vs 83 ± 3%, p = 0.001). On multivariate analysis, preoperative AF was identified as an independent predictor of overall mortality (hazard ratio 1.67; 95% confidence interval 1.15 to 2.42; p = 0.007). At 10 years, patients with paroxysmal AF had lower survival and higher heart failure rate than patients in SR (78 ± 3% vs 66 ± 6%) but had a better outcome compared with those with permanent AF (66 ± 6% vs 53 ± 6%, p = 0.022). Patients with AF had a significantly higher rate of postoperative LVD (23.3% vs 13.4%, p = 0.007). In conclusion, preoperative AF is a predictor of long-term mortality and postoperative LVD after MVRp for MVP. To improve postoperative outcome, surgery in these patients should be performed before onset of AF.


Subject(s)
Atrial Fibrillation/complications , Heart Valve Prosthesis Implantation , Mitral Valve Prolapse/complications , Ventricular Dysfunction, Left/etiology , Aged , Atrial Fibrillation/diagnosis , Atrial Fibrillation/epidemiology , Echocardiography , Electrocardiography , Female , France/epidemiology , Humans , Incidence , Male , Middle Aged , Mitral Valve Prolapse/diagnostic imaging , Mitral Valve Prolapse/surgery , Postoperative Period , Preoperative Period , Retrospective Studies , Survival Rate/trends , Treatment Outcome , Ventricular Dysfunction, Left/diagnostic imaging
12.
Nature ; 502(7470): 219-23, 2013 Oct 10.
Article in English | MEDLINE | ID: mdl-24108054

ABSTRACT

Temporal changes in the Earth's magnetic field, known as geomagnetic secular variation, occur most prominently at low latitudes in the Atlantic hemisphere (that is, from -90 degrees east to 90 degrees east), whereas in the Pacific hemisphere there is comparatively little activity. This is a consequence of the geographical localization of intense, westward drifting, equatorial magnetic flux patches at the core surface. Despite successes in explaining the morphology of the geomagnetic field, numerical models of the geodynamo have so far failed to account systematically for this striking pattern of geomagnetic secular variation. Here we show that it can be reproduced provided that two mechanisms relying on the inner core are jointly considered. First, gravitational coupling aligns the inner core with the mantle, forcing the flow of liquid metal in the outer core into a giant, westward drifting, sheet-like gyre. The resulting shear concentrates azimuthal magnetic flux at low latitudes close to the core-mantle boundary, where it is expelled by core convection and subsequently transported westward. Second, differential inner-core growth, fastest below Indonesia, causes an asymmetric buoyancy release in the outer core which in turn distorts the gyre, forcing it to become eccentric, in agreement with recent core flow inversions. This bottom-up heterogeneous driving of core convection dominates top-down driving from mantle thermal heterogeneities, and localizes magnetic variations in a longitudinal sector centred beneath the Atlantic, where the eccentric gyre reaches the core surface. To match the observed pattern of geomagnetic secular variation, the solid material forming the inner core must now be in a state of differential growth rather than one of growth and melting induced by convective translation.

13.
Nature ; 490(7418): 89-93, 2012 Oct 04.
Article in English | MEDLINE | ID: mdl-23038471

ABSTRACT

No consensus has been reached so far on the properties of the geomagnetic field during reversals or on the main features that might reveal its dynamics. A main characteristic of the reversing field is a large decrease in the axial dipole and the dominant role of non-dipole components. Other features strongly depend on whether they are derived from sedimentary or volcanic records. Only thermal remanent magnetization of lava flows can capture faithful records of a rapidly varying non-dipole field, but, because of episodic volcanic activity, sequences of overlying flows yield incomplete records. Here we show that the ten most detailed volcanic records of reversals can be matched in a very satisfactory way, under the assumption of a common duration, revealing common dynamical characteristics. We infer that the reversal process has remained unchanged, with the same time constants and durations, at least since 180 million years ago. We propose that the reversing field is characterized by three successive phases: a precursory event, a 180° polarity switch and a rebound. The first and third phases reflect the emergence of the non-dipole field with large-amplitude secular variation. They are rarely both recorded at the same site owing to the rapidly changing field geometry and last for less than 2,500 years. The actual transit between the two polarities does not last longer than 1,000 years and might therefore result from mechanisms other than those governing normal secular variation. Such changes are too brief to be accurately recorded by most sediments.

14.
Eur J Echocardiogr ; 12(9): 702-10, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21821606

ABSTRACT

AIMS: Left ventricular (LV) dysfunction is the first cause of late mortality after mitral valve surgery. In this retrospective analysis, we studied the association between preoperative echocardiographic LV measures and occurrence of LV dysfunction after mitral valve repair (MVR). METHODS AND RESULTS: Between 1991 and 2009, 335 consecutive patients underwent MVR for severe mitral regurgitation due to leaflet prolapse in our institution. Echocardiography was performed preoperatively and at 10.8 (9.1-12.0) months after surgery in 303 patients who represented the study population. Cardiac events were recorded during follow-up. LV ejection fraction (EF) decreased from 68 ± 9% before surgery to 59 ± 9% post-operatively (P < 0.001). Preoperative EF <64% and LV end-systolic diameter (ESD) ≥ 37 mm were the best cut-off values for the prediction of post-operative LV dysfunction (EF < 50%). On the basis of a combined analysis, the occurrence of post-operative LV dysfunction was 9% when EF was ≥ 64% and LVESD < 37 mm, 21% with EF < 64% or LVESD ≥ 37 mm, and 33% with EF < 64% and LVESD ≥ 37 mm (P for trend < 0.001). The combined variable EF < 64% and LVESD ≥ 37 mm added incremental prognostic value to the multivariable regression model (P = 0.001). CONCLUSION: Simple preoperative echocardiography measures allow the prediction of LV dysfunction after MVR in patients with leaflet prolapse. Patients with preoperative EF ≥ 64% and LVESD < 37 mm incur relatively low risk of post-operative LV dysfunction.


Subject(s)
Mitral Valve Insufficiency/surgery , Postoperative Complications/diagnosis , Stroke Volume , Ventricular Dysfunction, Left/diagnostic imaging , Ventricular Dysfunction, Left/etiology , Aged , Echocardiography, Doppler , Female , Humans , Logistic Models , Male , Mitral Valve Insufficiency/etiology , Mitral Valve Prolapse/complications , Proportional Hazards Models , ROC Curve , Ventricular Dysfunction, Left/physiopathology
16.
Nature ; 465(7294): 74-7, 2010 May 06.
Article in English | MEDLINE | ID: mdl-20445627

ABSTRACT

The magnetic field inside the Earth's fluid and electrically conducting outer core cannot be directly probed. The root-mean-squared (r.m.s.) intensity for the resolved part of the radial magnetic field at the core-mantle boundary is 0.3 mT, but further assumptions are needed to infer the strength of the field inside the core. Recent diagnostics obtained from numerical geodynamo models indicate that the magnitude of the dipole field at the surface of a fluid dynamo is about ten times weaker than the r.m.s. field strength in its interior, which would yield an intensity of the order of several millitesla within the Earth's core. However, a 60-year signal found in the variation in the length of day has long been associated with magneto-hydrodynamic torsional waves carried by a much weaker internal field. According to these studies, the r.m.s. strength of the field in the cylindrical radial direction (calculated for all length scales) is only 0.2 mT, a figure even smaller than the r.m.s. strength of the large-scale (spherical harmonic degree n

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