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Biomedical subjects

M Rubenfire

Publications and source records attributed to M Rubenfire.

123 records · Page 7Linked to original sources

Potential clinical and economic effects of homocyst(e)ine lowering.

BACKGROUND: Elevated total homocyst(e)ine levels (>/=11 micromol/L) have been identified as a potential risk factor for coronary heart disease. However, the benefits expected from lowering homocyst(e)ine levels with folic acid and vitamin B(12) supplementation have yet to be demonstrated in clinical trials. SUBJECTS AND METHODS: We constructed a decision analytic model to estimate the clinical benefits and economic costs of 2 homocyst(e)ine-lowering strategies: (1) "treat all"-no screening, daily supplementation with folic acid (400 microg) and vitamin B(12) (cyanocobalamin; 500 microg) for all; (2) "screen and treat"-screening, followed by daily supplementation with folic acid and vitamin B(12) for individuals with elevated homocyst(e)ine levels. Simulated cohorts of 40-year-old men and 50-year-old women in the general population were evaluated. In the base-case analysis, we assumed that lowering elevated levels would reduce excess coronary heart disease risk by 40%; however, this assumption and others were evaluated across a broad range of potential values using sensitivity analysis. Primary outcomes were discounted costs per life-year saved. RESULTS: Although the treat-all strategy was slightly more effective overall, the screen and treat strategy resulted in a much lower cost per life-year saved ($13,600 in men and $27,500 in women) when compared with no intervention. Incremental cost-effectiveness ratios for the treat-all strategy compared with the screen and treat strategy were more than $500,000 per life-year saved in both cohorts. Sensitivity analysis showed that cost-effectiveness ratios for the screen and treat strategy remained less than $50,000 per life-year saved under several unfavorable scenarios, such as when effective homocyst(e)ine lowering was assumed to reduce the relative risk of coronary heart disease-related death by only 11% in men or 23% in women. CONCLUSIONS: Homocyst(e)ine lowering with folic acid and vitamin B(12) supplementation could result in substantial clinical benefits at reasonable costs. If homocyst-(e)ine lowering is considered, a screen and treat strategy is likely to be more cost-effective than universal supplementation. Arch Intern Med. 2000;160:3406-3412.

Coronary Disease↗

Treatment strategies for management of serum lipids: lessons learned from lipid metabolism, recent clinical trials, and experience with the HMG CoA reductase inhibitors.

The Adult Treatment Panel (ATP) guidelines, published initially in 1988 and revised in 1993, are based on sentinel observations and early clinical trials in support of treating and preventing coronary artery disease by cholesterol lowering. With the conclusion of several large long-term trials using HMG CoA reductase inhibitors for primary and secondary coronary prevention, the ATP II recommendations, which remain remarkably accurate, can be supplemented with more evidence-based strategies. Increasing evidence suggests that thoughtful lipid management for coronary prevention should include a more complete assessment of lipoproteins with an emphasis on apolipoproteins, triglycerides, and very low-density (VLDL) remnant particles, LDL particle size, and lipoprotein(a). This review summarizes clinically relevant lipid metabolism with an emphasis on the concept of atherogenic plasma lipids, discusses the clinical benefits and specific uses of each of the lipid-lowering drug classes, and provides an analysis of recent cholesterol-lowering primary and secondary coronary prevention trials from which a new treatment strategy can be derived.

Clinical Trials as Topic↗

Cardiovascular Fitness and Rehabilitation Program, Sinai Hospital of Detroit.

Rehabilitation of persons with cardiac disease involves restoring and maintaining optimal physical, psychologic, occupational, social, and recreational status. It is based on the belief that adequate physical fitness and reduction of psychologic symptoms, including depression and poor self-image, can be attained by physical conditioning and education. The hospital-based and extended community-center program of Sinai Hospital of Detroit provides the environment for this effort.

Electrocardiography↗

Secondary pulmonary hypertension--diagnosis and management.

Secondary pulmonary hypertension (SPHtn) is generally attributable to abnormalities in structure or function of the heart or lung parenchyma. While often defined as a physiologic parameter, pulmonary hypertension (PHtn) can be a major contributor to death and disability in cardiopulmonary diseases. Both detection and management are a challenge. We will review the pathophysiology, diagnostic tools, and treatment strategies in SPHtn with an emphasis on cor pulmonale associated with chronic obstructive pulmonary disease (COPD), pulmonary vasculopathies, and pulmonary embolus. The pathophysiology and common etiologies of SPHtn can be divided into three major categories: (1) elevated pulmonary venous pressure (LV failure and mitral valve disease), (2) pulmonary vascular occlusive disease with or without pulmonary parenchymal disease (pulmonary emboli, COPD, connective tissue diseases), and (3) hypoxemia (sleep apnea). The echo-Doppler is a simple cost-effective tool for detecting PHtn, evaluating right ventricular function, and distinguishing common etiologies such as abnormal systolic and diastolic left ventricular function and mitral valve disease. The ventilation-perfusion radionuclide scan can be used to exclude thromboembolic PHtn, but a helical computer tomography with contrast or pulmonary angiography are necessary to distinguish patients that may benefit from a pulmonary thromboendarterectomy. The six minute walk oxygen saturation test is useful as a quantitative measure of functional capacity, prognosis, response to therapy, and oxygen requirement. Treatment strategies in cor pulmonale are tailored to the specific diagnosis, but generally include proper nutrition, exercise, oxygen supplementation, medications such as digoxin, diuretics, anti-coagulation, and pulmonary vasodilator therapy in selected patients.

Heart↗

Noninvasive external recording of cardiac conduction system (His bundle) activity.

Successful and adequate external recording of the cardiac conduction system from the body's surface can be accomplished in 80 to 90 percent of subjects studied. High-gain amplification, signal averaging, and triggering with a conditioned QRS signal results in good recording reproducibility. Averaging of 128 consecutive cycles is adequate, but on occasion averaging of 256 cycles may yield better results. The patients's QRS signal triggers the transfer of signals, which are digitized and stored during the preceding P-R interval. Comparison of external recordings with direct invasive recordings in animals and patients shows good correlation between the major His bundle deflections. The advantages of the system developed include its mobility, triggering the QRS with pretrigger data processing, and instantaneous display on Polaroid photograph. Future research should concentrate on further miniaturization and simplification of the instrumentation, detailed experimental comparison between direct and external recordings for identification of deflections and their origin, further study of the recording lead system, and the most appropriate method of information display.

Animals↗