Progress in cardiovascular diseases
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Prog Cardiovasc Dis · Jan 2000
ReviewThe emerging role of low-molecular-weight heparin in cardiovascular medicine.
Although unfractionated heparin is widely used in the treatment of acute coronary syndromes, it has several pharmacokinetic, biophysical, and biological limitations. The practical advantages and success of low-molecular-weight heparin administered subcutaneously without laboratory monitoring for the treatment of venous thromboembolism have prompted a number of randomized studies investigating the efficacy and safety of these agents in patients with acute coronary syndromes. This article will review the limitations of unfractionated heparin and the mechanisms by which low-molecular-weight heparin overcomes these limitations, as well as the results of recent trials involving low-molecular-weight heparin in the management of patients with acute coronary syndromes.
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Prog Cardiovasc Dis · Jan 2000
ReviewDetection of pulmonary embolism by D-dimer assay, spiral computed tomography, and magnetic resonance imaging.
Pulmonary embolism (PE) remains difficult to diagnose. Ventilation perfusion lung scan, the standard diagnostic test for PE, has poor overall sensitivity. The gold standard examination, pulmonary angiography, is invasive and has some risk, making clinicians reluctant to refer patients. ⋯ MRI is also useful for imaging the pulmonary arterial vasculature, but remains experimental. Although a more accurate assessment of the sensitivity of these new modalities will need to wait until a large angiographically controlled study, such as the planned PIOPED II, can be done, D-Dimer assay and spiral CT are often useful in the detection of pulmonary embolism. The authors make recommendations for their use in a diagnostic algorithm, as alternatives to the standard ventilation perfusion lung scan.
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Prog Cardiovasc Dis · Jul 1999
ReviewDietary salt reduction in hypertension--what is the evidence and why is it still controversial?
The link between sodium intake and hypertension remains controversial because of inconsistency between early epidemiologic studies, which showed a strong positive relationship between salt intake and blood pressure/incidence of hypertension, and more recent studies, which showed only modest decreases in blood pressure with sodium reduction, particularly in the normotensive population. In addition, there is clinical evidence that sodium is related to target organ damage such as left ventricular hypertrophy and renal disease. ⋯ Whether dietary sodium reduction should be recommended for the general population remains questionable because of marginal benefit and the suggestion of possible deleterious effects on cardiovascular outcomes independent of blood pressure. This paper will review the definition and methods used in determining salt sensitivity, the evidence linking sodium intake and target organ damage, and modern studies of salt and blood pressure.
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Aggressive cholesterol lowering with 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitor (statin) therapy has contributed to the substantial decrease in coronary heart disease (CHD) morbidity and mortality in recent years, as documented in a number of controlled clinical trials in both primary- and secondary-prevention patients. Although benefit was first established in patients with severe hypercholesterolemia, more recent trials have extended the benefit to patients with mildly to moderately elevated cholesterol. In addition to improvements on the lipid profile, statins appear to confer nonlipid benefits, such as improved endothelial function, modification of plaque cellularity, and plaque stabilization.
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Prog Cardiovasc Dis · Mar 1998
ReviewPerioperative cardiac evaluation for noncardiac surgery noninvasive cardiac testing.
Prognostic risk stratification to identify perioperative and long-term cardiac risk in selected patients undergoing noncardiac surgery is part of good clinical practice. Exercise variables associated with significant increased risk include poor functional capacity (eg, <4 metabolic equivalents), marked exercise-induced ST segment shift or angina at low workloads, and inability to increase or actually decrease systolic blood pressure with progressive exercise. Approximately 40% of patients tested before peripheral vascular surgery will have an abnormal exercise electrocardiogram (ECG). ⋯ Myocardial perfusion variables predictive of increased cardiac events include severity of the perfusion defect, number of reversible defects, extent of fixed and reversible defects, increased lung uptake of thallium-201, and marked ST segment changes associated with angina during the test. The reported sensitivity and specificity of dobutamine-induced echocardiographic wall motion abnormalities in patients with peripheral vascular disease is similar to myocardial perfusion scintigraphy, but the confidence limits are wider due to the smaller sample size in these more recent studies. In conclusion, noninvasive cardiac testing should be used selectively in patients undergoing noncardiac surgery; the results provide useful estimates of short- and long-term risk of cardiac events, and the magnitude of abnormal response on noninvasive testing should be used to formulate decisions regarding the need for coronary angiography and subsequent revascularization.