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Biomedical subjects

M Rubenfire

Publications and source records attributed to M Rubenfire.

At least 37 records · Page 2Linked to original sources
PubMed1999

Echocardiographic predictors of an adverse response to a nifedipine trial in primary pulmonary hypertension: diminished left ventricular size and leftward ventricular septal bowing.

BACKGROUND: The clinical course in primary pulmonary hypertension (PPH) is improved by calcium channel blocker therapy in those with a favorable hemodynamic response during a trial of high-dose oral nifedipine. Although trials of nifedipine are performed only in patients who demonstrate pulmonary vasodilator reserve to short-acting agents, this response does not predict the safety of nifedipine treatment, which can result in severe first-dose hypotension and death. STUDY OBJECTIVES: To identify echocardiographic parameters that predict first-dose nifedipine-induced hypotension in patients with PPH. METHODS: The pretrial echocardiograms of 23 consecutive PPH patients (mean age, 42.3 +/- 13 years; 77% female) undergoing evaluation of pulmonary vasodilator reserve with nifedipine were analyzed. Patients were classified as those who suffered first-dose nifedipine hypotension (group 1) and those who did not (group 2). Echocardiographic measures of chamber size and septal geometry in the two groups were compared. RESULTS: Five measures reflecting diminished left ventricular (LV) size and leftward ventricular septal bowing were found to be associated with nifedipine hypotension: LV transverse diameter in systole (LVDs; p = 0.007), LV transverse diameter in diastole (LVDd; p = 0.05), LV area in systole (LVAs; p = 0.009), LV area in diastole (LVAd; p = 0.03), the ratio of RV to LVAs (p = 0. 02), and leftward ventricular septal bowing (p = 0.01). The LV dimensions found to best predict nifedipine-induced hypotension were LVDs < 2.7 cm, LVDd < 4.0 cm, LVAs < 15.5 cm(2), and LVAd < 20.0 cm(2). CONCLUSIONS: Readily available echocardiographic parameters in patients with PPH are predictive of nifedipine-induced hypotension, and can be used to select patients in whom a trial of nifedipine should be avoided.

Administration, Oral↗
PubMed1999

How to manage secondary pulmonary hypertension.

Establishing an underlying cause and treatment plan for patients with pulmonary hypertension presents a significant challenge to practicing physicians. Doppler echocardiography is a simple, cost-effective tool for detecting pulmonary hypertension and evaluating right ventricular function. Nonspecific therapy (use of digoxin and diuretics, anticoagulation) for pulmonary hypertension and right ventricular failure achieves a degree of symptomatic improvement and should be considered in patients with moderate to severe disease. CTEPH should be considered in patients with dyspnea. Because severs forms of pulmonary hypertension usually are not discovered until late in the disease course, a high level of suspicion is required when evaluating symptoms and risk factors consistent with pulmonary vascular disease. Pulmonary hypertension is classified as idiopathic, or primary, when no secondary cause can be identified. Primary pulmonary hypertension is a devastating disease that largely affects young women. Significant advances in treatment have been made and will be discussed in detail in part 2 of this article.

Chronic Disease↗
PubMed1999

How to manage primary pulmonary hypertension. Giving hope to patients with a life-threatening illness.

Primary pulmonary hypertension presents a challenge to practicing physicians, in both diagnosis and management. Exposure to anorexigens and complaints of dyspnea and fatigue should prompt careful physical examination and Doppler echocardiography to assess patients for pulmonary hypertension. The burden on office practitioners is heavy, considering how often fatigue and dyspnea are reported, but the key is recognizing when these findings are out of proportion to the patient's well appearance. The discovery of epoprostenol therapy has revolutionized the approach to primary pulmonary hypertension. It has markedly improved quality of life and extended survival in patients with the condition, and it has changed the physician's role from providing emotional support to dying patients to providing management of a chronic disease.

Antihypertensive Agents↗
PubMed1998

Inhaled nitric oxide in primary pulmonary hypertension: a safe and effective agent for predicting response to nifedipine.

OBJECTIVES: The purpose of this study was to assess the utility of inhaled nitric oxide (NO), a selective pulmonary vasodilator, for predicting the safety and acute hemodynamic response to high-dose oral nifedipine in primary pulmonary hypertension (PPH). BACKGROUND: A significant decrease in pulmonary vascular resistance with an oral nifedipine challenge is predictive of an improved prognosis, and potential clinical efficacy in PPH. However, the required nifedipine trial carries significant first-dose risk of hypotension. While inhaled NO has been recommended for assessing pulmonary vasodilator reserve in PPH, it is not known whether it predicts the response to nifedipine. METHODS: Seventeen patients with PPH undergoing a nifedipine trial were assessed for hemodynamic response to inhaled NO at 80 parts per million for 5 minutes. The nifedipine trial consisted of 20 mg of nifedipine hourly for 8 hours unless limited by hypotension or intolerable side effects. Patients were classified as responders and nonresponders with positive response defined as > or =20% reduction in mean pulmonary artery pressure (mPA) or pulmonary vascular resistance (PVR) with the vasodilator administration. RESULTS: NO was safely administered to all participants. Seven of 17 (41.2%) responded to NO, and 8 of the 17 to nifedipine (47.1%). Nifedipine was safely administered in 14 of the 17. Three suffered either mild or severe hypotension, including one death. All NO responders also responded to nifedipine, and 9 of the 10 NO nonresponders were nifedipine nonresponders, representing a sensitivity of 87.5%, specificity of 100%, and overall predictive accuracy of 94%. All NO responders tolerated a full nifedipine trial without hypotension. There was a highly significant correlation between the effects of NO and nifedipine on PVR (r=0.67, p=0.003). CONCLUSIONS: The pulmonary vascular response to inhaled NO accurately predicts the acute hemodynamic response to nifedipine in PPH, and a positive response to NO is associated with a safe nifedipine trial. In patients comparable with those evaluated, a trial of nifedipine in NO nonresponders appears unwarranted and potentially dangerous.

Administration, Inhalation↗
PubMed1998

Gender differences in barriers to lifestyle change for cardiovascular disease prevention.

Achieving and maintaining a healthy lifestyle are important aspects of a cardiovascular disease prevention program. Few data have evaluated barriers to lifestyle change by gender. We studied self-reported barriers to lifestyle change and evaluated support systems to make positive changes in 293 patients (186 men, 107 women) enrolled in a multidisciplinary preventive cardiology clinic. Subjects were asked to rate barriers and support systems on a scale of 1 to 5, with 1 being very important and 5 not important. Women ranked self-esteem as the most important barrier and rated it significantly higher than did men (p = 0.0003). Women also rated money, knowledge, skills, and stress significantly higher than did men (p < 0.05). Physicians were rated as the most important source of support for both genders. Women, compared with men, rated dietitians, exercise physiologists, nurses, counselors, family members, and social/religious groups as more important sources of support. These data suggest that gender differences exist in barriers to lifestyle change. Psychosocial factors should be considered important elements of programs designed to help patients make positive lifestyle changes.

Adult↗
PubMed1998

Sonographic detection of xanthomas in normal-sized Achilles' tendons of individuals with heterozygous familial hypercholesterolemia.

OBJECTIVE: The objective of this study was to evaluate how well high-frequency linear array sonography reveals xanthomas in the Achilles' tendons of individuals with heterozygous familial hypercholesterolemia before the xanthomas enlarge the tendons enough to become palpable. SUBJECTS AND METHODS: Both Achilles' tendons of 23 individuals (18 female and five male; age range, 16-69 years old) who had heterozygous familial hypercholesterolemia but no clinically apparent Achilles' tendon xanthomas were studied with high-frequency linear array sonography. Hypoechoic areas, consistent with xanthomas, were noted. RESULTS: Xanthomas were revealed in 36 (78%) of 46 tendons and 19 (83%) of 23 individuals. CONCLUSION: Sonography reveals Achilles' tendon xanthomas in many individuals with heterozygous familial hypercholesterolemia before the xanthomas are clinically apparent. Because tendon xanthomas in a hypercholesterolemic individual are essentially pathognomonic of heterozygous familial hypercholesterolemia and are a mainstay in its diagnosis, our study suggests that sonography is useful in the early diagnosis of heterozygous familial hypercholesterolemia.

Achilles Tendon↗
PubMed1997

Clinical predictors of oxidized low-density lipoprotein in patients with coronary artery disease.

Oxidized low-density lipoprotein (LDL) may play a key role in the initiation and progression of atherosclerosis. Risk factors for elevated levels of oxidized LDL are not well established and may be important in identifying individuals who may benefit from antioxidant supplementation or interventions to reduce oxidant stress. The purpose of this study was to determine if clinical parameters predict levels of oxidized LDL. We evaluated the relation between clinical parameters and oxidized LDL in 45 nonsmoking, nondiabetic patients (39 men and 6 women) with coronary artery disease. Oxidized LDL was assessed by measurement of conjugated dienes, lipid peroxides, and thiobarbituric reactive substances (TBARS) at 0 hours to evaluate baseline oxidant stress and postincubation with an oxidizing agent to assess the capacity of LDL for peroxidation. Results were lipid standardized and were not materially altered by multivariate adjustment. Significant predictors of increased oxidized LDL included female sex, family history of premature cardiovascular disease, increased percent body fat, increased body mass index, increased heart rate at rest, history of smoking, exercise <4 times per week, and no regular wine consumption. These data suggest that clinical parameters correlate with levels of oxidized LDL and may be useful in identifying patients at risk for increased oxidant stress.

Adult↗
PubMed1997

Antioxidant nutrient supplementation reduces the susceptibility of low density lipoprotein to oxidation in patients with coronary artery disease.

OBJECTIVE: This study sought to determine the effect of antioxidant supplementation on the susceptibility of low density lipoprotein (LDL) to oxidation in patients with established cardiovascular disease (CVD). BACKGROUND: Data are inconsistent regarding the role of antioxidant nutrients in the prevention of CVD. METHODS: The study design was a 12-week, double-blind, placebo-controlled clinical trial. Patients with CVD (n = 45) were randomized to 1) placebo control; 2) 400 IU of vitamin E, 500 mg of vitamin C, 12 mg of beta-carotene (mid-dose); or 3) 800 IU of vitamin E, 1,000 mg of vitamin C, 24 mg of beta-carotene (high dose) daily. Reduced susceptibility of LDL to oxidation was estimated by an increase in lag phase (minutes). Baseline and 6- and 12-week measurements of lipoproteins and lag phase were obtained. Plasma levels of antioxidants were measured at baseline and 12 weeks. RESULTS: Concentrations of alpha-tocopherol, vitamin C and beta-carotene significantly increased in the mid- and high dose groups during the trial. Lag phase significantly increased from baseline (190.1 +/- 63.8 min [mean +/- SD]) to 12 weeks (391.1 +/- 153.0 min) in the high dose group (p < 0.01). A nonsignificant increase in lag phase in the mid-dose group was observed during the same time interval. A dose response was found for mean percent change from baseline to 12 weeks for lag phase for the placebo, mid- and high dose groups (p = 0.004 for trend). CONCLUSIONS: A high dose combination of antioxidant nutrients reduces the susceptibility of LDL to oxidation in patients with CVD and may be useful in secondary prevention.

Adult↗
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↗