Search PubMed⌕ Search

Biomedical subjects

R R Miller

Publications and source records attributed to R R Miller.

At least 217 records · Page 12Linked to original sources
PubMed1982

Effects of digoxin on left ventricular function in coronary artery disease patients.

To assess whether digitalis modifies or prevents the deterioration of the left ventricular ejection fraction and wall motion during acute ischemia, we performed gated blood pool radionuclide ventriculograms in 15 patients with angiographically documented coronary artery disease. All patients were studied in the resting state and during maximal supine bicycle exercise, both before and 1 hour after 1 mg intravenous digoxin. There was no significant difference, pre-digoxin vs post-digoxin, in exercise tolerance (415 +/- 84 vs 418 +/- 107 seconds), number of segments with abnormal resting wall motion (12 vs 11) or exercise wall motion (21 vs 19). Ten patients developed angina during the same exercise load, irrespective of digoxin administration. Twelve patients had subnormal left ventricular ejection fraction during exercise pre-digoxin, vs 13 patients post-digoxin (P = ns). In the resting state, the left ventricular ejection fraction was higher after digoxin (53 +/- 14% pre vs 58 +/- 14% post, P less than 0.05). During exercise, however, the left ventricular ejection fraction was not significantly improved after digoxin (50 +/- 16% pre vs 53 +/- 17% post, P = ns). These data indicate that although acute administration of digoxin improves the resting left ventricular function, it does not improve exercise tolerance to angina. Furthermore, intravenous digoxin does not appear to prevent the deterioration of left ventricular wall motion and ejection fraction during exercise induced ischemia.

Blood Pressure↗
PubMed1982

Comparison of cold pressor and exercise radionuclide angiocardiography in coronary artery disease.

To investigate the role of the cold pressor test (CPT) with radionuclide angiocardiography in the diagnosis of coronary artery disease (CAD), we performed angiocardiography in 52 patients (18 with angiographically normal coronary arteries and 34 with CAD) during the resting state, CPT, and supine bicycle exercise (EX). In normal subjects, left ventricular ejection fraction (EF) was unchanged between rest (58 +/- 9%) and CPT (59 +/- 9%, p = ns), but increased during maximal EX (69 +/- 9%, p less than 0.01). In CAD patients, EF fell from 55 +/- 9% at rest to 49 +/- 9% during CPT (p less than 0.01), and to 53 +/- 11% during EX (p = ns vs. rest). Twenty-seven CAD patients (79%) developed new or worsening areas of dyssynergy during CPT, vs. 25 patients (73%) during EX. Thus, the cold pressor test with radiocardiography appears to be a useful noninvasive test for the diagnosis and functional evaluation of CAD, particularly in patients unable to perform a satisfactory exercise test.

Adult↗
PubMed1981

History of clinical pharmacy and clinical pharmacology.

The purpose of the Symposium on Clinical Pharmacy and Clinical Pharmacology is to describe the present and future functional roles of clinical pharmacists and clinical pharmacologists in drug research, professional education, and patient care. Clinical pharmacy is a relatively new professional discipline, being only about 15 years old. This new breed of pharmacists is patient rather than drug product oriented. The discipline arose out of dissatisfaction with old practice norms and the pressing need for a health professional with a comprehensive knowledge of the therapeutic use of drugs. The clinical pharmacy movement began at the University of Michigan in the early 1960s, but much of the pioneering work was done by David Burkholder, Paul Parker, and Charles Walton at the University of Kentucky in the latter part of the 1960s. Clinical pharmacology is a professional discipline that combines basic pharmacology and clinical medicine. Its development began in the early 1950s, primarily as a result of the efforts of Harry Gold. It has had a slower growth than clinical pharmacy but it has made many important contributions to our knowledge of human pharmacology and the rational use of drugs.

Drug Information Services↗
PubMed1981

Beneficial effects of nitroprusside administration on left ventricular dysfunction and myocardial ischemia in severe aortic stenosis.

Although surgical therapy is effective for reducing excessive left ventricular (LV) afterload in valvular aortic stenosis (AS), salutary short-term medical treatment has been lacking. Since we have shown LV systolic pressure (SP) is altered concordant with arterial SP in AS by vasopressors, the present study evaluated efficacy of nitroprusside (NP) on LV function, energetics, and perfusion in 15 severe AS patients. NP infusion (average 33 micron/min) proved beneficial in each: LVSP 192 mm Hg was reduced to 164; arterial SP decrement equaled LVSP change; LV end-diastolic pressure 19 mm Hg declined to 10: cardiac index (2.73 L/min/m2) and heart rate were unaltered; total systemic vascular resistance 1433 dsc-5 decreased to 1201; elevated LV stroke work index 92 gm.m/m2 was diminished to 74. Simultaneously, LV O2 consumption fell, LV diastolic flow was unchanged, while subendocardial perfusion increased. Thus cautious NP therapy with careful monitoring provided marked reduction of LV affected and improved LV function, energetics, and coronary flow distribution.

Aged↗
PubMed1981

Sequential postoperative assessment of left ventricular performance with gated cardiac blood pool imaging following aortocoronary bypass surgery.

The comparative effects of normothermic intermittent ischemic arrest (IIA) and cardioplegia (C) on left ventricular (LV) performance were assessed by gated cardiac blood pool imaging in 57 patients undergoing aortocoronary bypass surgery. In 34 patients, IIA was employed; 23 patients received C. Patients were studied preoperatively, sequentially in the immediate postoperative period at 30-minute intervals, and at 1 week after the operation, C and IIA groups did not differ in mean (+/- SEM) age, anginal class, number of diseased vessels, previous myocardial infarction, or preoperative ejection fraction (EF)(50 +/- 3% vs 50 +/- 2% [p = ns]). Aortic cross clamp time was greater with C than IIA (50 +/- 5 minutes vs 28 +/- 3 minutes [p = 0.001]). During the six sequential postoperative studies, transient LV dysfunction (greater than or equal to 7% decrease in absolute EF) was observed in 10 patients receiving C and in 16 patients receiving IIA. By time of discharge, 24 of 26 patients had returned to preoperative EF. Mean EF at discharge in the cardioplegia group did not differ compared to preoperative EF; in the IIA group, EF increased compared to preoperative EF (50 +/- 2% vs 55 +/- 2% [p < 0.01]). These data suggest that in patients with normal preoperative LV performance both C and IIA afford satisfactory myocardial preservation during aortocoronary bypass surgery.

Aorta↗
PubMed1981

Combined vasodilator and inotropic therapy of heart failure: experimental and clinical concepts.

Vasodilators facilitate ventricular emptying by affording earlier onset of left ventricular (LV) ejection and increased stroke volume with achievement of a reduced end-systolic pressure and volume. Agents with positive inotropic properties increase stroke volume by shifting the end-systolic pressure-volume curve to the left through augmented force and velocity of contraction. With impedence reduction, improvement in pump performance occurs concomitant with reduced cardiac energy requirements (MVO2); positive inotropic agents most circumstances increase MVO2. The combination of a vasodilator and positive inotropic agent, as opposed to either alone, in the conscious animal shifts to the left and increases the slope of the LV end-systolic pressure-volume relation. Cardiac efficiency, defined by the slope of the relation between stroke volume and systolic tension, is increased by the combination of the drugs. In clinical heart failure, nitroprusside alone lowers LV preload with a modest increase in cardiac output (CO); dopamine markedly increases CO with little fall in LV preload. In combination the two agents achieve the individual beneficial effects of each drug, and cardiac efficiency indices are improved. Thus combined vasodilator and inotropic therapy appears to have a sound physiologic rationale and clinically documented beneficial effect superior to either modality alone.

Animals↗
PubMed1981

Effects of exercise training on left ventricular performance and myocardial perfusion in patients with coronary artery disease.

To determine the effects of exercise training on left ventricular performance and myocardial perfusion in coronary artery disease, rest and exercise radionuclide angiocardiography and thallium-201 scintigraphy were performed before and after 12 weeks of training in 16 coronary patients. After training, 15 of the 16 patients had improved exercise tolerance; total treadmill exercise duration increased from (mean +/- standard error of the mean) 491 +/- 37 to 602 +/- 31 seconds (p less than 0.01), and the estimated rate of oxygen consumption (VO2 max) increased from 29.4 +/- 1.4 to 33.8 +/- 1.2 ml/kg per min (p less than 0.001). Resting left ventricular ejection fraction increased from 52 +/- 4 to 57 +/- 4 percent (p less than 0.02); no change occurred in left ventricular functional reserve assessed by ejection fraction and regional wall motion response to exercise at the same rate-pressure product before and after training. Myocardial perfusion at equivalent pre- and post-training cardiac work loads during exercise and on redistribution was unchanged by training. It is concluded that in patients with coronary heart disease, physical training increases exercise tolerance, and results in minimal improvement in resting left ventricular systolic performance. Functional reserve of both left ventricular systolic performance and the coronary circulation appears to be unchanged by exercise training. These data suggest that the beneficial effects of training for 12 weeks in patients with coronary artery disease predominantly result from factors other than improvement in left ventricular pump performance or perfusion.

Adult↗
PubMed1981

Left ventricular diastolic performance at rest and during exercise in patients with coronary artery disease. Assessment with first-pass radionuclide angiography.

We used first-pass radionuclide angiocardiography to assess filling fraction during the first third of diastole, peak filling rate and peak filling rate during the first third of diastole as indexes of left ventricular diastolic performance at rest and after upright bicycle exercise in 32 normal patients and 68 patients with coronary artery disease. The mean filling fraction was unchanged from rest to exercise in normal patients (47+/- 15% vs 46 +/- 13%; NS). Even in 49 coronary patients with normal (greater than or equal to 50%) ejection fraction at rest, filling fraction was less than that in normal patients at rest (35 +/- 11% vs 47 +/- 15%, p less than 0.001). Despite similar resting heart rates, patients with coronary disease had lower (p less than 0.001) peak filling rate and peak filling rate during the first third of diastole than normal patients. With exercise, filling fraction decreased (p less than 0.001) from the resting value in coronary patients. These data suggest that (1) indexes of diastolic performance can be noninvasively assessed at rest and during exercise using first-pass radionuclide angiocardiography, (2) abnormalities in early diastolic performance are often present at rest in patients with coronary artery disease despite normal systolic performance, and (3) exercise-induced ischemia results in increased early diastolic dysfunction in patients with coronary disease.

Adult↗