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Biomedical subjects

L B McGuire

Publications and source records attributed to L B McGuire.

At least 19 recordsLinked to original sources
PubMed1990

A long run for a short jump: understanding clinical guidelines.

Clinical guidelines for application of medical technologies are being advanced as consensus recommendations by consumer groups, professional societies, and health care managers. Although different groups' guidelines for use of a given technology may vary--or even conflict--depending on the methods by which they were formulated, their proponents' interests, and the subjective values attached to potential outcomes, they make it possible to quantify somewhat and predict, on a population basis, clinical gains relative to costs. Clinical guidelines can introduce into patient-physician decision making systematic consideration of a given technology's demonstrated efficacy and its likely advantages compared with its personal and its societal costs. Provided there is flexibility to allow for individual departures from consensus recommendations and for development of new technologies, applying clinical guidelines in health care can serve both individual patients and society and help to balance their respective needs for informed decision making and for resource allocation.

Health Planning Guidelines↗
PubMed1983

Relation of therapeutic response to nifedipine to coronary anatomy and motion of S-T segment during unstable angina pectoris.

Of 77 patients hospitalized for unstable angina pectoris and failure of oral, dermal, or intravenous nitrates and/or beta blockade, 81 percent with negligible or single-vessel disease and 55 percent with two- or three-vessel disease showed response (p less than 0.05) to nifedipine therapy. Patients with either S-T elevation or no change during pain responded better (31 of 45) than those with any S-T depression (16 of 32; p less than 0.05). Patients with negligible or single-vessel disease had a higher prevalence of S-T elevation (13 of 16) than patients with two- or three-vessel disease (15 of 31; p = 0.004). S-T motion did not predict response in patients with two- or three-vessel disease, but did predict response in patients with negligible or single-vessel disease. On follow-up study at 9 +/- 8 (range one to 33) months, 39 of 42 who had shown response were free from pain. Three died from infarction without unstable angina. (range one to 33) months, 39 of 42 who had shown response were free from pain. Three died from infarction without unstable angina. Five who showed response had elective bypass surgery. The addition of nifedipine abolished or reduced pain episodes by more than 50 percent in 61 percent of patients with refractory unstable angina pectoris. Patients with negligible or single-vessel disease with S-T elevation benefit most. In patients with two- or three-vessel disease, the type of S-T motion did not predict response. Follow-up of all those with response indicated sustained amelioration by nifedipine therapy. Failure of nifedipine therapy should not be accepted until a dose of 120 mg per day has been achieved, or until intolerable side effects appear.

Adult↗
PubMed1981

Assessment of preoperative left ventricular function in patients with mitral regurgitation: value of the end-systolic wall stress-end-systolic volume ratio.

Twenty-one patients with symptomatic, chronic, severe mitral regurgitation (MR) but without other valvular heart disease or coronary disease were evaluated to determine which hemodynamic and angiographic factors might be prognostic of surgical outcome. Sixteen patients were in New York Heart Association functional classes I or II postoperatively and formed group A. One patient remained in class III postoperatively and four patients died perioperatively; they constitute group B. End-diastolic volume index (EDVI) was less for group A than for group B, 119 +/- 25 ml/m2 vs 170 +/- 28 ml/m2 (p less than 0.001). End-systolic volume index (ESVI) was also lower in group A, 39 +/- 19 ml/m2 vs 72 +/- 32 ml/m2 for group B (p less than 0.01). The ratio of end-systolic wall stress to end-systolic volume index (ESWS/ESVI) was examined in normal persons and in groups A and B. This ratio was significantly lower in both groups than in normal persons, indicating relatively greater end-systolic volume at a given wall stress, suggesting left ventricular dysfunction. The ESWS/ESVI ratio in group B, 2.2 +/- 0.2, was significantly less than in group A, 3.3 +/- 0.4 (p less than 0.001). The variables of age, pulmonary capillary wedge pressure, EDVI, ESVI, ejection fraction and the ESWS/ESVI ratio were subjected to stepwise discriminant multivariate analysis to determine if any were independent predictors of outcome. The only independent predictor determined by this method was the ESWS/ESVI ratio (p less than 0.001). We conclude that the ESWS/ESVI ratio may be helpful in evaluating left ventricular function and operative risk in patients with chronic, symptomatic MR.

Aged↗
PubMed1981

The uses and limits of standard exercise tests.

Standard exercise electrocardiography to detect coronary artery disease involves limitations of accuracy in a population of apparently healthy persons, to the extent that its value for counseling such individuals is doubtful. Among subjects being examined for chest pain, however, the accuracy of the exercise ECG in predicting coronary obstructive disease is better. In addition, the presence of more severe coronary obstructive disease tends to be associated with more distinctly abnormal tests at low levels of exercise. This tendency of association between marked ST-segment displacement at low exertion levels and more severe obstructive disease adds a measure of prognostic value to the standard exercise ECG in persons with chest pain or after myocardial infarction. The addition of either isotopic cardiac imaging or coronary arteriography to exercise ECG will be appropriate for situations in which either the ECG is known to be nonspecific or inadequate exercise is achieved.

Angina Pectoris↗
PubMed1979

The care of patients at increased risk of premature pacemaker failure.

During 1975 to 1977, a series of advisory notices from a pacemaker manufacturer alerted us to an increased probability of sudden, premature pacemaker failure in 217 patients. Three possible responses to these recalls were used among these patients: prophylactic pulse generator change, increased surveillance without pulse generator change, and routine surveillance with replacement only after pacing failure. During the three years after implantation of these pulse generators, 30 sudden failures and 19 incidents of rate decrease indicating impending failure were observed; all were corrected by pulse generator replacement. Among the 50 deaths were six for whom terminal pacemaker status information was inadequate, but overall mortality was not notably different from other pacing series. Consideration of recalls should include projected frequency of failure, expected mode of failure, patient dependence on pacing, and presence of coexisting diseases.

Arrhythmias, Cardiac↗
PubMed1978

The management of anticoagulation during noncardiac operations in patients with prosthetic heart valves. A prospective study.

Based on previous thromboembolic complications associated with the interruption of anticoagulation during subsequent noncardiac operations in patients with nonbiological mitral prostheses, a protocol was developed for this high risk group. We report the successful management of 26 such operations in which anticoagulation was interrupted for 12 hours and then rapidly restored by means of heparin in the postoperative period. Since an earlier study suggested no adverse effect from the interruption of chronic anticoagulants for three to five days among patients with isolated aortic valve prostheses, simple interruption was again employed during 16 subsequent noncardiac operative procedures in this group with no complications. There were three episodes of hemorrhage observed in patients receiving therapeutic doses of heparin postoperatively, but only one required blood replacement.

Anticoagulants↗