The New England journal of medicine
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Mutations in potassium-channel genes KCNQ1 (LQT1 locus) and KCNH2 (LQT2 locus) and the sodium-channel gene SCN5A (LQT3 locus) are the most common causes of the long-QT syndrome. We stratified risk according to the genotype, in conjunction with other clinical variables such as sex and the length of the QT interval. ⋯ The locus of the causative mutation affects the clinical course of the long-QT syndrome and modulates the effects of the QTc and sex on clinical manifestations. We propose an approach to risk stratification based on these variables.
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Streptococcus pneumoniae is the chief cause of pneumonia in older adults, but it remains unclear whether use of the pneumococcal polysaccharide vaccine alters the overall risk of community-acquired pneumonia. In a large population of older adults, we assessed the effectiveness of the pneumococcal vaccine. ⋯ These findings support the effectiveness of the pneumococcal polysaccharide vaccine for the prevention of bacteremia, but they suggest that alternative strategies are needed to prevent nonbacteremic pneumonia, which is a more common manifestation of pneumococcal infection in elderly persons.
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Clinical Trial
Nitroprusside in critically ill patients with left ventricular dysfunction and aortic stenosis.
Vasodilators are considered to be contraindicated in patients with severe aortic stenosis because of concern that they may precipitate life-threatening hypotension. However, vasodilators such as nitroprusside may improve myocardial performance if peripheral vasoconstriction is contributing to afterload. ⋯ Nitroprusside rapidly and markedly improves cardiac function in patients with decompensated heart failure due to severe left ventricular systolic dysfunction and severe aortic stenosis. It provides a safe and effective bridge to aortic-valve replacement or oral vasodilator therapy in these critically ill patients.