RESUMO
BACKGROUND: Mitral valve stenosis is a common manifestation of chronic rheumatic heart disease. The presence of spontaneous echo contrast in the left atrium and left atrial appendage has been reported to be an independent predictor of thrombo-embolic risk in patients with mitral stenosis. The objective of this study was to retrospectively investigate various clinical and echocardiographic variables to predict the spontaneous echo contrast in these patients. METHODOLOGY: This is a bicentric retrospective study which includes 159 cases of symptomatic mitral stenosis from January 2011 to June 2012. All of the patients had transthoracic and transesophageal echocardiography. Patients who had significant mitral regurgitation (> Grade I), significant aortic valve disease, previous mitral valvulotomy and anticoagulation or antiplatelet therapy were excluded from the study. Our study population was divided into two groups based on the presence (Group I) or absence (Group II) of spontaneous echo contrast. RESULT: Left atrial spontaneous contrast was present in 34.6% of cases. Patients in this group have more frequent atrial fibrillation (P = 0.001), larger left atrial area (P = 0.027) and diameter (P=0.023), smaller mitral valve area (P = 0.025), and higher mean transmitral diastolic gradient (p = 0.003) as compared to patients without spontaneous echo contrast. There were no significant differences in the mean age (p = 0.38), duration of symptoms (p = 0.4) and left ventricular ejection fraction (p = 0.7) between patients with and without spontaneous echo contrast. On multivariate analysis, only mitral valve area and transmitral diastolic gradient (OR: 18.753, 1.21, CI [1,838-191,332], [1,064-1,376], p: 0.013, 0.004, respectively) were found to be independently associated to the presence of spontaneous echo contrast. CONCLUSION: Patients with severe rheumatic mitral stenosis in atrial fibrillation or sinus rhythm have a higher risk of developing spontaneous echo contrast. These patients might benefit from prophylactic anticoagulation. The long-term outcomes can be ascertained in a study over a longer period and with periodic follow-up.
RESUMO
BACKGROUND & OBJECTIVES: Despite the increasing number of reported autochthonous malaria cases in Nouakchott and the identification of Anopheles arabiensis as the major malaria vector in this Saharan city, anopheline larval habitats have never been identified so far. The objective of this study was to identify and characterize anopheline larval habitats in Nouakchott. METHODS: During September and October 2012, samples from pools of rainwater, water discharged from standpipes and household drinking water tanks in the districts of Dar Naim, Teyarett and Arafat were analyzed for the presence/absence of anopheline larvae and physicochemical characterization of breeding habitats. RESULTS: Of the 51 prospected water bodies, eight consisting of seven water discharged from standpipes and one household drinking water tank were productive for Anopheles sp. All emerged anopheline mosquitoes from the positive dipping were morphologically identified as members of the An. gambiae complex. Multivariate regression analyses showed that a salinity up to 0.1 g/l and a shaded situation were respectively protective factors against high larval density in breeding sites (adjusted odds ratio = 0.62, 95% CI [0.44-0.87], p = 0.0052 and adjusted odds ratio = 0.56, 95% CI [0.44-0.71, p <0.0001] and a pH up to 7.61 was a risk factor for high larval density in breeding sites (adjusted odds ratio = 1.56, 95% CI [1.25-1.95], p = 0.0001). INTERPRETATION & CONCLUSION: The study demonstrated in Nouakchott that despite an arid and dry climate, human practices have contributed to the establishment of favourable environmental conditions for the development of anopheline mosquitoes and, therefore, maintaining malaria transmission in this Saharan city. The core malaria vector control intervention as the use of long-lasting insecicidal nets (LLINs) could be complemented in Nouakchott by larval source control. In this area, appropriate larval control measures may be recommended in line with an integrated vector management (IVM) approach.