Progress in cardiovascular diseases
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Various forms of smokeless tobacco (mainly snuff and chewing tobacco) cause an immediate increase in heart rate and blood pressure, but regular users of smokeless tobacco do not have permanent changes of heart rate or blood pressure when not exposed to tobacco. Cardiac output during workload and maximal working capacity are unaffected. Users of smokeless tobacco usually do not have the biochemical stigmata that regular smokers have. ⋯ Results on the risk for myocardial infarction have provided conflicting evidence, 2 case-control studies showing the same risks as in non-tobacco users and one cohort study showing an increased risk for cardiovascular death. In all, the use of smokeless tobacco (with snuff being the most studied variant) involves a much lower risk for adverse cardiovascular effects than smoking does. Whether or not the apparent risk reduction is a useful strategy to help inveterate smokers to quit is a matter of debate, as are the public health effects of a high prevalence of snuff use in some populations.
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Numerous medications not intended for cardiac use (including antibiotics, histamine blockers, and antipsychotic medications) incidentally block potassium channels in myocardial cells, prolong the QT interval, and may trigger malignant arrhythmias. Although the odds for a given patient for developing arrhythmias are small, the number of patients receiving such drugs is enormous. Most patients developing proarrhythmia have additional risk factors that could be easily identified from their medical history. ⋯ The references in each of these reports also were reviewed to identify additional publications. In addition, we reviewed the published reviews and the Internet sites dealing with drug-induced arrhythmias. All the original articles quoted in these reviews and Web sites were examined critically.
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Prog Cardiovasc Dis · Sep 2001
ReviewPharmacologic conversion of atrial fibrillation: a systematic review of available evidence.
This report reviews the efficacy of currently available antiarrhythmic agents for conversion of atrial fibrilation (AF) to normal sinus rhythm (NSR). A systematic search of literature in the English language was done on computerized databases, such as MEDLINE, EMBASE, and Current Contents, in reference lists, by manual searching, and in contact with expert informants. Published studies involving humans that described the use of antiarrhythmic therapy for conversion of AF to NSR were considered and only studies that examined the use of agents currently available in the United States were included. ⋯ For conversion of recent-onset AF of longer duration (less than 90 days), i.v. ibutilide may be considered a preferred agent. For patients with chronic AF and left ventricular dysfunction, direct current cardioversion is the preferred conversion method. Larger, well-designed randomized controlled trials with clinically important endpoints in specific populations of AF patients are needed.
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Prog Cardiovasc Dis · Mar 2001
ReviewCoronary artery surgery for ischemic heart failure: risks, benefits, and the importance of assessment of myocardial viability.
Heart failure and left ventricular dysfunction are common and are most often caused by myocardial ischemia/infarction secondary to occlusive coronary artery disease. Although recent refinements in medical therapy have resulted in improved survival, morbidity and mortality remain high in patients with advanced heart failure. ⋯ However, patients with established postischemic heart failure, significant myocardial viability, and coronary artery anatomy amenable to surgical revascularization can derive significant functional and survival benefit after coronary artery surgery, albeit with an increased perioperative risk. We discuss the role of coronary artery surgery in ischemic heart failure and review the evidence for such an approach.
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This article describes the important role of magnetic resonance imaging (MRI) in noninvasively assessing human focal ischemic stroke. Conventional MRI, diffusion-weighted and/or perfusion-weighted imaging have been used to facilitate both the qualitative and quantitative evaluation of heterogeneity of ischemic brain tissue. ⋯ Dynamic changes in the evolution of ischemic tissue to infarction are also discussed. Recovery from acute stroke was studied with blood oxygenation level-dependent functional MRI to investigate the neural mechanisms for recovery from aphasia after stroke.