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Biomedical subjects

R C Schlant

Publications and source records attributed to R C Schlant.

At least 19 recordsLinked to original sources
PubMed1992

Blood lipid measurements. Variations and practical utility.

OBJECTIVE: To describe the magnitude and impact of the major biological and analytical sources of variation in serum lipid and lipoprotein levels on risk of coronary heart disease; to present a way to qualitatively estimate the total intraindividual variation; and to demonstrate how to determine the number of specimens required to estimate, with 95% confidence, the "true" underlying total cholesterol value in the serum of a patient. DATA SOURCES: Representative references on each source of variation were selected from more than 300 reviewed publications, most published within the past 5 years, to document current findings and concepts. Most articles reviewed were in English. STUDY SELECTIONS: Studies on biological sources of variation were selected using the following criteria: representative of published findings, clear statement of either significant or insignificant results, and acquisition of clinical and laboratory data under standardized conditions. Representative results for special populations such as women and children are reported when results differ from those of adult men. DATA EXTRACTION: References were selected based on acceptable experimental design and use of standardized laboratory lipid measurements. DATA SYNTHESIS: The lipid levels considered representative for a selected source of variation arose from quantitative measurements by a suitably standardized laboratory. Statistical analysis of data was examined to assure reliability. The proposed method of estimating the biological coefficient of variation must be considered to give qualitative results, because only two or three serial specimens are collected in most cases for the estimation. CONCLUSIONS: Concern has arisen about the magnitude, impact, and interpretation of preanalytical as well as analytical sources of variation on reported results of lipid measurements of an individual. Preanalytical sources of variation from behavioral, clinical, and sampling sources constitute about 60% of the total variation in a reported lipid measurement of an individual. A technique is presented to allow physicians to qualitatively estimate the intraindividual biological variation of a patient from the results of two or more specimens reported from a standardized laboratory and to determine whether additional specimens are needed to meet the National Cholesterol Education Program recommendation that the intraindividual serum total cholesterol coefficient of variation not exceed 5.0. A National Reference Method Network has been established to help solve analytical problems.

Analysis of Variance↗
PubMed1991

Events in the cardiac arrhythmia suppression trial: baseline predictors of mortality in placebo-treated patients.

Patients randomized to placebo in the encainide and flecainide arms of the Cardiac Arrhythmia Suppression Trial (CAST) have been found to have a relatively low 1-year mortality rate of 3.9% in comparison with previous studies of patients in the postmyocardial infarction period. To determine the comparability of CAST with previous studies, baseline variables were examined in the 743 patients randomized to placebo in the flecainide and encainide arms of CAST. Twenty-three baseline characteristics were correlated with major outcome events: arrhythmic death (16 events), total mortality (26 events) and congestive heart failure (51 events). On multivariate analysis the risk of new or worsening congestive heart failure was significantly associated with diuretic use, diabetes, high New York Heart Association functional class, age, prolonged QRS duration and low ejection fraction. The risk of arrhythmic death or resuscitated cardiac arrest was significantly associated with an index Q wave myocardial infarction, history of heart failure, use of digitalis, diabetes and prolonged QRS duration. Total mortality or resuscitated cardiac arrest was significantly associated with an index Q wave myocardial infarction, diabetes, ST segment depression, high functional class, prolonged QRS duration and low ejection fraction. The variables at baseline associated with mortality from all causes or arrhythmic death or resuscitated cardiac arrest and heart failure in the CAST placebo-treated patients are similar to those identified in previous postmyocardial infarction studies. Thus, the observation of increased mortality in CAST associated with the administration of encainide and flecainide for suppression of ventricular premature depolarizations is probably applicable to any comparably defined group of patients in the postmyocardial infarction period.

Aged↗
PubMed1990

Lewis Dexter.

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History, 20th Century↗
PubMed1990

Nitrate tolerance.

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Administration, Cutaneous↗
PubMed1989

A comparison of oral milrinone, digoxin, and their combination in the treatment of patients with chronic heart failure.

We randomly assigned 230 patients in sinus rhythm with moderately severe heart failure to treatment with digoxin, milrinone, both, or placebo. The effects of each were compared during a 12-week, double-blind trial. Treatment with milrinone or digoxin significantly increased treadmill exercise time as compared with placebo (by 82 and 64 seconds respectively; 95 percent confidence limits, 44 and 123, and 30 and 100). Both treatments reduced the frequency of decompensation from heart failure, from 47 percent with placebo to 34 percent with milrinone (P less than 0.05; 95 percent confidence limits, 22 and 46) and 15 percent with digoxin (P less than 0.01; 95 percent confidence limits, 7 and 26). However, the clinical condition of 20 percent of the patients taking milrinone deteriorated within two weeks after treatment was begun, as compared with only 3 percent of those taking digoxin (P less than 0.05). The left ventricular ejection fraction at rest was not significantly changed by milrinone (+0.2 percent; 95 percent confidence limits, -1.5 and 1.9), but it was increased by digoxin (+1.7 percent; P less than 0.01; 95 percent confidence limits, -0.03 and 3.4) and decreased by placebo (-2.0 percent; 95 percent confidence limits, -3.8 and -0.1). Three-month survival was related inversely to the base-line ejection fraction. Analysis of mortality from all causes according to the intention to treat suggested an adverse effect of milrinone (P = 0.064). After adjustment for an excess of patients with lower ejection fractions randomly assigned to receive milrinone, this trend was not significant (P = 0.26). Increased ventricular arrhythmias occurred more frequently in patients who received milrinone than in those who did not (18 vs. 4 percent; P less than 0.03). We conclude that milrinone significantly increased exercise tolerance and reduced the frequency of worsened heart failure. However, in the population of patients studied, milrinone or the combination of milrinone and digoxin offered no advantage over digoxin alone. Furthermore, our data suggest that milrinone may aggravate ventricular arrhythmias.

Administration, Oral↗
PubMed1989

Usefulness of calcium entry blockers during and after percutaneous transluminal coronary artery angioplasty.

Calcium entry blockers can decrease myocardial ischemia and coronary spasm in association with percutaneous transluminal coronary artery angioplasty (PTCA). Restenosis after PTCA has not been shown to be statistically decreased by nifedipine or diltiazem in patients who clinically did not have coronary spasm. Patients who have evidence of coronary spasm before or at PTCA have a higher incidence of restenosis after PTCA, but this is decreased by treatment with calcium entry blockers. Most patients at Emory receive a calcium entry blocker before and after PTCA while in the hospital. After discharge, long-term therapy is given to select patients, especially those with any evidence of coronary vasospasm or patients with incompletely revascularized, multivessel disease. All patients receive aspirin before and long-term after PTCA. Some physicians give calcium entry blockers to all patients after PTCA. There is a need for larger, controlled clinical trials to evaluate the current use of calcium entry blockers before, during, and after PTCA as well as other therapeutic agents to prevent acute and chronic restenosis.

Angioplasty, Balloon, Coronary↗
PubMed1989

Current therapeutic options for the patient with a recent myocardial infarction.

The treatment of acute myocardial infarction continues to change rapidly. The mortality of many subgroups of patients sustaining acute myocardial infarction has significantly decreased. Current therapeutic modalities provide the physician with many agents that favorably influence the course of acute myocardial infarction. Improving diagnostic techniques provide the physician with the means to identify subsets of patients who are at very low risk or very high risk of recurrent myocardial infarction and to improve the management of these subsets.

Electrocardiography↗