Search PubMed⌕ Search

Biomedical subjects

M Rubenfire

Publications and source records attributed to M Rubenfire.

At least 19 recordsLinked to original sources
PubMed1996

Silent ischemic cardiomyopathy and left coronary ostial stenosis secondary to radiation therapy.

A 55-year-old woman presented with profound congestive heart failure 23 years following mediastinal radiation. Ejection fraction (EF) was 35%. Symptoms markedly improved and EF increased to > 55% following saphenous vein bypass for > or = 80% ostial left main stenosis. Radiation therapy, a known risk factor for coronary atherosclerosis, may present with reversible severe silent ischemia.

Coronary Artery Bypass↗
PubMed1995

Physicians and nurses can be effective educators in coronary risk reduction.

OBJECTIVES: 1) To compare the impact of a brief physician or nurse education session with the impact of education provided by dietitians on patient knowledge regarding coronary risk factors, dietary recommendations, and compliance, and 2) to determine the value of additional formal dietary counseling on knowledge, dietary fat, and serum lipids. DESIGN: Primary care physicians and their office nurses were compared with inpatient dietitians by evaluating patient performance on a standardized test and three-day dietary food choices. Neither the educators nor the patients were aware of the study. Supplemental information was provided by a study dietitian and patients were reevaluated six weeks later. SETTING: Preventive cardiology program in a university-affiliated teaching hospital. PARTICIPANTS: Fifty consecutive patients referred to a preventive cardiology program who had received dietary and cardiac risk factor information within the preceding six weeks by a physician and office nurse (27) or an inpatient dietitian (23) were enrolled. Forty-five patients completed the study objectives. INTERVENTIONS: The patients completed a three-day food record, fasting lipids, and a test of knowledge of coronary risk factors and dietary concepts. The correct answers were discussed and a standard American Heart Association phase I diet was recommended. Six weeks later dietary food records, fasting lipids, and the test were repeated. MEASUREMENTS AND MAIN RESULTS: By participant recall, the dietitians (group II) spent an average of 30.6 +/- 25 minutes, compared with 8.2 +/- 14.4 minutes by the physicians and nurses (group I) (p < 0.05). Group II patients had a higher total knowledge score, but they were no better in risk factors, weight control, or calculated dietary fat or cholesterol. There was no correlation between time spent and percentage of calories from fat or total test score. Six weeks after the program instruction the mean cholesterol level for all the participants was reduced, and group II had a lower fat intake than did group I, which was associated with significantly lower serum cholesterol, not present at entry. CONCLUSION: Primary care physicians and their office nurses, using less time than do dietitians, can be effective educators in providing patient education for coronary risk reduction and dietary fat intake. A second formal dietary consultation appears beneficial in improving compliance and lipid control.

Cholesterol↗
PubMed1995

Wolff-Parkinson-White syndrome and radiofrequency ablation.

Wolff-Parkinson-White syndrome is the most common of the preexcitation syndromes and is due to an accessory pathway connecting the atria and ventricles. Asymptomatic patients do not require empirical therapy. Ongoing drug therapy has traditionally been the choice for older symptomatic patients and patients with infrequent symptoms. However, more definitive therapy, ie, surgical or nonsurgical ablation, may be preferable for younger patients, patients with medically refractory arrhythmias, and patients at high risk for sudden death. Ablation by radiofrequency current is now being routinely performed because it appears to be cost-effective and has been found to be safe and efficient if performed by skilled operators. Clinical experience of this procedure is limited, however, and long-term effects still need to be established.

Adult↗
PubMed1994

Psyllium for the reduction of cholestyramine-associated gastrointestinal symptoms in the treatment of primary hypercholesterolemia.

OBJECTIVE: To determine if the bulk-forming laxative, psyllium hydrophilic mucilloid (PHM), reduces the gastrointestinal side effects and enhances the cholesterol-lowering efficacy of cholestyramine resin in patients with primary hypercholesterolemia. DESIGN: After a dietary lead-in period and 6 weeks of treatment with cholestyramine, the study followed a double-blinded, placebo-controlled, crossover format. SETTING: Lipid clinic affiliated with a large metropolitan community hospital. PARTICIPANTS: Twenty-seven randomly selected male and female patients with a diagnosis of primary hypercholesterolemia. Entry criteria required a fasting low-density lipoprotein cholesterol (LDL-C) concentration of 4.91 mmol/L (190 mg/dL) or greater and a triglyceride concentration of less than 2.26 mmol/L. Patients using steroids, beta-blockers, thiazide diuretics, and lipid-lowering agents, or having a history of allergy to psyllium or aspartame were excluded. INTERVENTION: The study consisted of four interventional phases of 6 weeks' duration that included (1) dietary stabilization (National Cholesterol Education Program Step I Diet); (2) cholestyramine therapy (4 g twice daily); (3) cholestyramine with study medication (PHM [5.1 g twice daily] or placebo); and (4) cholestyramine with crossover to alternate study medication. MAIN RESULTS: Following the 6-week dietary lead-in phase, four patients were eliminated from the study because their fasting LDL-C concentrations fell below 4.14 mmol/L (160 mg/dL), and one patient was eliminated because testosterone therapy was initiated by his internist. The remaining 22 patients entered the cholestyramine treatment phase. Four left the study within 2 weeks because of intolerable gastrointestinal tract symptoms. The 18 patients who completed this phase demonstrated significant reductions in their plasma total cholesterol (7.27 vs 6.67 mmol/L [281 vs 258 mg/dL]) and LDL-C (5.38 vs 4.63 mmol/L [208 vs 179 mg/dL]) concentrations compared with baseline levels. The addition of PHM to the cholestyramine regimen provided a tendency toward further reductions in total cholesterol and LDL-C levels (6.67 vs 6.46 mmol/L [258 vs 250 mg/dL] and 4.63 vs 4.29 mmol/L [179 vs 166 mg/dL], respectively), although statistical significance was not achieved. Psyllium hydrophilic mucilloid significantly reduced the frequency and severity of constipation, abdominal discomfort, and heartburn. No reports of new gastrointestinal tract symptoms or untoward effects were noted with the addition of PHM. CONCLUSION: These data suggest that the addition of PHM to cholestyramine therapy may improve a patient's compliance by reducing the associated gastrointestinal tract side effects.

Abdominal Pain↗
PubMed1994

Efficacy and safety of pravastatin in the long-term treatment of elderly patients with hypercholesterolemia.

PURPOSE: Elevated cholesterol levels are a major risk factor for coronary heart disease, which remains a significant problem in patients beyond age 65 years. Because drug therapy for the control of hypercholesterolemia in elderly patients is frequently considered to be indicated, we investigated the efficacy and safety of pravastatin in the treatment of elderly subjects with primary hypercholesterolemia. PATIENTS AND METHODS: In this 96-week, multicenter, double-blind, placebo-controlled study, 142 subjects (95 women, 47 men) 64 to 90 years of age with elevated cholesterol levels despite dietary intervention were randomized to receive pravastatin 20 mg at bedtime or matching placebo (2:1). Dosage could be doubled after 8 weeks, a bile acid-binding resin could be added after 16 weeks, and nicotinic acid or probucol could be added after 32 weeks, as needed, to adequately lower the low-density lipoprotein cholesterol (LDL-C) levels. RESULTS: Significant reductions in the levels of LDL-C (-30.9%), total cholesterol (Total-C; -21.9%), and triglycerides (TG; -16.7%) and significant increases in the levels of high-density lipoprotein cholesterol (HDL-C; 11.3%) were noted in the group receiving pravastatin treatment at 16 weeks (P < or = 0.001 compared with baseline, P < or = 0.01 compared with placebo). The cholesterol-lowering effects of pravastatin were sustained throughout the 96 weeks of the trial. Pravastatin was well tolerated, with an overall incidence of adverse events nearly identical to that of placebo. CONCLUSIONS: In this study, pravastatin was well tolerated and effective in lowering LDL-C, Total-C, and TG and in raising HDL-C during long-term treatment of elderly patients with primary hypercholesterolemia.

Aged↗
PubMed1994

Early detection of abnormal coronary flow reserve in asymptomatic men at high risk for coronary artery disease using positron emission tomography.

BACKGROUND: The objective of this study was to compare coronary flow reserve (CFR) as a measure of vascular integrity in asymptomatic middle-aged men with family history of coronary artery disease (CAD) and a high-risk lipid profile with men without risk factors for CAD using positron emission tomography (PET). Previous studies suggested that the assessment of CFR is a sensitive means to detect vascular abnormalities before angiographic appearance of CAD. N-13 ammonia PET scanning allows noninvasive evaluation of regional and global myocardial blood flow and thereby quantification of CFR. METHODS AND RESULTS: We used dynamic N-13 ammonia PET imaging in conjunction with intravenous adenosine to assess regional and global CFR in asymptomatic middle-aged men with high risk (group 1, n = 16) and men without any known risk factors (group 2, n = 11) for CAD. Group 1 patients were selected based on positive family history of CAD, one or more lipid abnormalities, and a normal stress test. No patient had history of diabetes or hypertension. A three-compartment tracer kinetic model developed and validated in our institution was used to calculate myocardial blood flow. Absolute myocardial blood flow (mL/100 g per minute) was calculated in five territories for each patient. CFR was defined as the ratio of blood flow during maximum pharmacological vasodilatation to blood flow at rest. Comparisons of CFR between the two groups of patients were performed. The mean age was similar between groups (group 1, 49.3 +/- 0.5 years; group 2, 48.1 +/- 8.7 years; P = NS). Group 1 had higher total cholesterol (mg/dL) (241 +/- 43 versus 173 +/- 34, P < .001), total cholesterol to high-density lipoprotein cholesterol ratio (6.4 +/- 1.6 versus 4.1 +/- 1.4, P < .001), and low-density lipoprotein cholesterol (mg/dL) (167 +/- 33 versus 107 +/- 32). No group 1 patient had evidence of ischemia by exercise ECG or exercise of pharmacological radionuclide perfusion studies. The mean global absolute myocardial blood flow at rest was not significantly different among groups (group 1, 76 +/- 18; group 2, 66 +/- 8; P = NS; (in mL/100 g per minute). However, blood flow after adenosine infusion was higher for group 2 (group 1, 217 +/- 56; group 2, 264 +/- 39; P < .001), which resulted in a larger CFR for group 2 (group 1, 2.93 +/- 0.86; group 2, 4.27 +/- 0.52; P < .001). Univariate linear regression analysis revealed significant negative correlation of CFR to total cholesterol (P < .05, r = -.41), low-density lipoprotein (P < .05, r = -.38), and total cholesterol to high-density lipoprotein cholesterol ratio (P < .05, r = -.47). CONCLUSIONS: Noninvasive quantification of absolute myocardial blood flow by N-13 ammonia PET allows the detection of abnormal vasodilatory response to intravenous adenosine in male patients with family history of CAD and high-risk lipid profiles. Early assessment of alterations of vascular reactivity to adenosine in relation to high-risk lipid profiles in asymptomatic men may allow early detection of preclinical atherosclerosis and may initiate modification and/or elimination of risk factors that may slow, retard, or even reverse the progression of CAD.

Adenosine↗
PubMed1993

Neural network in the clinical diagnosis of acute pulmonary embolism.

The purpose of this investigation was to test the hypothesis that computer-based pattern recognition can accurately assess the likelihood of acute pulmonary embolism (PE) based on readily obtainable clinical characteristics. Data were obtained from 1,213 patients who participated in the collaborative study of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). Characteristics of the history, physical examination, electrocardiograph, chest radiograph, and arterial blood gases of patients with suspected acute PE were presented to a back propagation neural network. The 1,213 patients were divided into training set A (n = 606) and test set B (n = 607). These groups were then reversed into training set B (n = 607) and test set A (n = 606). A receiver operating characteristic (ROC) curve was constructed from PIOPED clinical assessment, and from neural network clinical assessment in groups A and B. Areas under the respective ROC curves were 0.7450, 0.7477, and 0.7324. All differences were not significant. Areas under ROC curves for PIOPED clinical assessment combined with ventilation/perfusion (V/Q) scan results were compared with neural network clinical assessment combined with V/Q scan results in groups A and B. The respective ROC areas were 0.8324, 0.8203, 0.8496 (all differences not significant). These data show that neural networks were able to predict the clinical likelihood of PE with an accuracy comparable to experienced clinicians.

Acute Disease↗
PubMed1991

The effect of pravastatin on plasma lipoprotein and apolipoprotein levels in primary hypercholesterolemia. The Southeastern Michigan Collaborative Group.

Pravastatin is a metabolic product of mevastatin and a potent inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase. It was investigated for its cholesterol-lowering properties in a double-blind, placebo-controlled, multicenter study of 82 patients with primary hypercholesterolemia. Following a 6- to 8-week dietary lead-in period, patients were randomized to twice-daily placebo or active drug for 16 weeks. Patients receiving 10 mg of pravastatin twice a day for 8 weeks experienced mean total cholesterol and low-density lipoprotein cholesterol (LDL-C) level reductions of 20% (6.85 vs 5.48 mmol/L [265 vs 212 mg/dL]) and 28% (5.17 vs 3.75 mmol/L [200 vs 145 mg/dL]), respectively. At 20 mg twice a day for an additional 8 weeks, pravastatin reduced plasma total cholesterol, LDL-C, and apolipoprotein B-100 levels by 23% (6.85 vs 5.30 mmol/L [265 vs 205 mg/dL]), 31% (5.17 vs 3.59 mmol/L [200 vs 139 mg/dL]), and 23% (118 vs 91 mg/dL), respectively. High-density lipoprotein cholesterol (HDL-C), HDLb-C, HDLb-C, and apolipoprotein A-I plasma concentrations increased by 11%, 60%, 7%, and 10%. Plasma triglyceride concentrations decreased in both the pravastatin- and placebo-treated patients. Pravastatin was generally well tolerated and an effective agent for the treatment of primary hypercholesterolemia.

Apolipoproteins↗
PubMed1990

Mexiletine. Long-term efficacy and side effects in patients with chronic drug-resistant potentially lethal ventricular arrhythmias.

The antiarrhythmic efficacy of mexiletine hydrochloride (Mexitil) was evaluated in 100 patients with potentially lethal and drug-resistant ventricular arrhythmia. The efficacy of arrhythmia suppression was assessed by Holter monitoring. The overall arrhythmia suppression of ventricular premature contractions of 70% and greater was low and seen in only 22% of patients, with an additional 16% responding to a combination of mexiletine and an additional antiarrhythmic drug. The suppression of high-grade forms, couplets of 90% and greater, and complete abolition of nonsustained runs of ventricular tachycardia was achieved in 22% of patients, with 9% responding to the addition of another antiarrhythmic agent. Ventricular premature contractions, couplets, and nonsustained ventricular tachycardia were suppressed in only 16% of the cohort. The drug was poorly tolerated, with intolerable side effects developing in 49% of patients receiving mexiletine alone and in 57% of patients receiving a combination of antiarrhythmic agents. Tolerable adverse effects were relatively common but transient and dose related.

Administration, Oral↗
PubMed1989

Classification of antiarrhythmic drugs.

Although many classification schemes for antiarrhythmic drugs have been proposed, the system introduced by Vaughan Williams and later modified by Harrison has been widely accepted. This classification system is comprised of four categories. Class I agents block sodium channels. Class II agents are Beta blockers. Class III agents prolong the cardiac action potential. Class IV agents are calcium channel blockers. This classification scheme, based largely on clinical observation continues to be useful almost two decades after its introduction. The electrophysiologic bases, strengths and weaknesses of this system are discussed.

Amiodarone↗
PubMed1989

Long-term efficacy and toxicity of high- and low-dose amiodarone regimens.

Amiodarone is an effective antiarrhythmic drug for the control of potentially lethal and lethal ventricular arrhythmias (VA). In the United States, a high-dose regimen has been used at the expense of a high toxicity profile for the control of lethal VAs. Significant antiarrhythmic efficacy has also been established with low-dose regimens, which carry a low rate of intolerable side effects (5.4%) when compared with the high-dose regimen (16.7%). The high incidence of tolerable and intolerable adverse side effects is probably related to high amiodarone loading (31.92 g) and maintenance doses (520 mg/d). In contrast, the low-dose regimen uses much lower loading (7.2 g) and maintenance (280 mg/d) doses.

Amiodarone↗
PubMed1989

Potentially lethal ventricular arrhythmias: from mundane to esoteric.

Patients with potentially lethal ventricular arrhythmias (VAs) represent a heterogenous group with frequent and high grade ventricular arrhythmias (including couplets and runs of nonsustained ventricular tachycardia), structural heart disease and decreased left ventricular function. This is a group at intermediate risk of sudden death, with risks varying from 10% to 38%. The electrical and mechanical risks of patients with potentially lethal VA is discussed in relation to their ability of promoting sudden death. The studies reviewing the impact of antiarrhythmic treatment on survival of patients with potentially lethal VA is discussed.

Arrhythmias, Cardiac↗
PubMed1989

Dopamine and dobutamine induce hypokalemia in anesthetized dogs.

Epinephrine-induced hypokalemia appears to be mediated by beta 2-agonist activation of Na+/K+ ATPase. To determine whether dopamine and dobutamine induce hypokalemia, eight adult mongrel dogs were anesthetized and studied in random crossover fashion. Potassium [K+] was measured with an ion-selective microelectrode, and central hemodynamics were measured continuously. After stabilization, dopamine and dobutamine were infused at doses of 2, 4, 8, and 20 micrograms/kg/min (15-min increments/dose), and 0.9% NaCl was infused at equivalent volumes, with a 1-h washout between treatments. The mean change in [K+] at each infusion rate was compared between treatments among dogs with an adequate hemodynamic response. Among dopamine responders (n = 5), [K+] decreased from 3.74 +/- 0.42 mEq/L at baseline to 3.63 +/- 0.51 at 2 micrograms/kg/min (p less than 0.02) and was not significantly different at higher doses. Among dobutamine responders (n = 7), [K+] decreased from 3.52 +/- 0.74 at baseline to 3.31 +/- 0.87 at 8 micrograms/kg/min (p less than 0.02) and 3.25 +/- 0.86 at 20 micrograms/kg/min (p less than 0.02), and was not significantly different at lower doses. We conclude that dopamine and dobutamine induce significant hypokalemia, consistent with their adrenergic agonist activity, and this may be related to the known arrhythmogenicity of these agents.

Anesthesia, Intravenous↗