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Biomedical subjects

R W Barnes

Publications and source records attributed to R W Barnes.

At least 37 records · Page 2Linked to original sources
PubMed1995

No association between serum ferritin and asymptomatic carotid atherosclerosis. The Atherosclerosis Risk in Communities (ARIC) Study.

A possible association between body iron stores, measured as serum ferritin, and carotid arterial intima-media thickening was investigated in the Atherosclerosis Risk in Communities Study during 1990-1992 using a matched case-control design. For a 143-micrograms/liter greater serum ferritin concentration (the interquartile range), the odds ratio for cases with carotid intima-media thickening versus controls was 1.12 (95% confidence interval 0.97-1.30). However, there was no association (odds ratio = 1.00) after adjusting for major cardiovascular risk factors. This analysis of carotid arterial intima-media thickening, a measure of early atherosclerosis, in relation to serum ferritin does not support the hypothesis that increased body iron stores increase the risk of atherosclerotic cardiovascular disease.

Arteriosclerosis↗
PubMed1995

Vascular holism: the epidemiology of vascular disease.

This article reviews the distinguishing features of epidemiology and clinical medicine and their interdependence in clinical epidemiology as applied to vascular disease. Selected literature is reviewed to emphasize the principles of clinical epidemiology for five vascular disorders: abdominal aortic aneurysms, lower extremity peripheral arterial occlusive disease, cerebrovascular disease, deep vein thrombosis and pulmonary embolism, and varicose veins. These vascular disorders are prevalent and pose significant risks for death and disability. Many have risk factors that can be controlled. All can be treated by vascular surgery, but outcomes including functional health and well-being may fall short of that which is implied in our traditional surgical literature. Appropriate allocation of resources to detect and treat vascular disease demands that clinicians not only assume responsibility for the care of individual patients but also develop a working knowledge of the clinical epidemiology of vascular health and disease and its management within populations.

Cross-Sectional Studies↗
PubMed1995

Association of vagal tone with serum insulin, glucose, and diabetes mellitus--The ARIC Study.

Reduced vagal activity assessed by heart rate variability (HRV) has been observed in studies of diabetics, but this association has not been reported at the population level. To investigate the association of HRV with diabetes mellitus, as well as fasting serum insulin, and glucose, we examined a stratified random sample of 1933 individuals (154 diabetics and 1779 non-diabetics), aged 45-65 years from the Atherosclerosis Risk in Communities (ARIC) study cohort. Two-minute, resting, supine beat-to-beat heart rate records were collected. Power spectral density estimation was used to derive HRV high frequency power (HF, 0.15-0.35 Hz) as the conventional marker of vagal function. Age, race, and gender-adjusted geometric means of HF were 0.78 and 1.27 (beat/min)(2) for diabetics and non-diabetics respectively (P for mean difference <0.01), reflecting a reduced vagal activity in diabetics. In individuals not diagnosed as diabetics, a graded, inverse association was observed between fasting serum insulin and HF (P for trend <0.01): the age, race, and gender-adjusted geometric mean values of HF in the lowest and highest quartiles of serum insulin were 1.34 and 1.14 (beat/minute)(2), respectively. A similar association was observed between glucose and HF in a univariate model, but not in the adjusted model. This first population-based study on this subject confirmed that diabetics have significantly lower vagal activity than non-diabetics. In individuals not diagnosed as diabetics, serum insulin, and, to a lesser degree, serum glucose were inversely associated with vagal function, suggesting a role in the pathogenesis of diabetic neuropathy.

Blood Glucose↗
PubMed1995

The non-invasive vascular laboratory: who needs it?

This paper attempts to answer the following four questions: Why test? What tests? Whom to test? and What costs? The author briefly reviews the reasons that physicians order tests and the currently acceptable and unacceptable indications and procedures for non-invasive vascular diagnostic testing. The background for economic analysis, including cost-benefit or cost-effective analysis, is reviewed. Finally, a Medline literature search of articles addressing the cost-effectiveness of non-invasive vascular techniques provides a basis for classification of these tests based on economic analysis.

Cost-Benefit Analysis↗
PubMed1995

Low serum albumin. Association with diabetes mellitus and other cardiovascular risk factors but not with prevalent cardiovascular disease or carotid artery intima-media thickness. The Atherosclerosis Risk in Communities (ARIC) Study Investigators.

We examined the association of serum albumin concentration with diabetes mellitus and other cardiovascular risk factors, prevalent cardiovascular disease, and ultrasonographically assessed carotid artery intima-media thickness using data from 45- to 64-year-old adults in the Atherosclerosis Risk in Communities (ARIC) Study. The mean albumin concentration was 0.04 to 0.12 g/L lower in participants with diabetes and 0.02 to 0.06 g/L lower in those with cardiovascular disease, compared to participants without these conditions. However, lower serum albumin level was also correlated with most traditional risk factors and hemostatic variables. On adjustment for these, there was essentially no association between serum albumin and prevalent cardiovascular disease. Likewise, there was no association between albumin and carotid intima-media thickness (a marker of atherosclerosis). While hypoalbuminemia may be a marker for chronic disease and perhaps renal loss of albumin, it seems unlikely that it is an important cause of atherosclerosis.

Arteriosclerosis↗
PubMed1995

Arterial wall thickness is associated with prevalent cardiovascular disease in middle-aged adults. The Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND AND PURPOSE: This study was done to assess the relationship between prevalent cardiovascular disease and arterial wall thickness in middle-aged US adults. METHODS: The association of preexisting coronary heart disease, cerebrovascular disease, and peripheral vascular disease with carotid and popliteal intimal-medial thickness (IMT) (measured by B-mode ultrasound) was assessed in 13,870 black and white men and women, aged 45 to 64, during the Atherosclerosis Risk in Communities (ARIC) Study baseline examination (1987 through 1989). Prevalent disease was determined according to both participant self-report and measurements at the baseline examination (including electrocardiogram, fasting blood glucose, and medication use). RESULTS: Across four race and gender strata, mean carotid far wall IMT was consistently greater in participants with prevalent clinical cardiovascular disease than in disease-free subjects. Similarly, the prevalence of cardiovascular disease was consistently greater in participants with progressively thicker IMT. The greatest differences in carotid IMT associated with prevalent disease were observed for reported symptomatic peripheral vascular disease (0.09 to 0.22 mm greater IMT in the four race-gender groups). CONCLUSIONS: These data document the substantially greater arterial wall thickness observed in middle-aged adults with prevalent cardiovascular disease. Both carotid and popliteal arterial IMT were related to clinically manifest cardiovascular disease affecting distant vascular beds, such as the cerebral, peripheral, and coronary artery vascular beds.

Age Factors↗
PubMed1994

Wound healing in forefoot amputations: the predictive value of toe pressure.

A retrospective study of 136 men undergoing forefoot amputation was done to test the hypothesis that preoperative toe pressure (TP) could predict the likelihood of wound healing. Demographic data included age, smoking history, diabetes mellitus (DM), hypertension, hyperlipidemia, and coronary artery disease. Clinical data included infection, preoperative arterial Doppler data, TP, wound disposition, concomitant revascularization (REV), and healing outcome. Among diabetics, no primary amputation healed with a preoperative TP < 38 mm Hg. Among REV diabetics, no healing occurred with a TP < 40 mm Hg after bypass, but no failures occurred either with a TP > 68 mm Hg or an increase in TP > or = 30 mm Hg after bypass. Nondiabetic patients exhibited no threshold TP values. Univariate analysis revealed that DM and REV were significantly different in the healed (N = 83) vs. nonhealed (N = 53) populations (p = 0.027 and 0.034). In healed patients mean TP (71.8 +/- 3.5 mm Hg SEM) was significantly higher than in nonhealed patients (45.1 +/- 4.3 mm Hg SEM, p = 0.000). Logistic regression analysis identified age > 60 years (p = 0.03), DM (p = 0.003), preoperative TP (p < 0.001), and REV (p < 0.001) as significant independent predictors of forefoot amputation healing. Healing probability was calculated and plotted vs. TP for subpopulations based on age, DM, and REV status for both primary forefoot amputation and amputation concomitant with bypass. In this study population, therefore, preoperative TP appeared to be a useful clinical tool for predicting the healing potential of both primary forefoot amputations and amputations plus concomitant bypass for any given patient.

Adult↗
PubMed1994

Carotid-subclavian bypass: a twenty-two-year experience.

PURPOSE: A retrospective review of 124 patients who underwent carotid-subclavian bypass from 1968 to 1990 was done to assess primary patency and symptom resolution. METHODS: Preoperative data included age, atherosclerosis risk factors, and indications for surgery. Perioperative data included mortality and morbidity rates and graft conduit. Postoperative follow-up assessed graft patency, resolution of symptoms, and late survival. RESULTS: Age ranged from 42 to 78 years (mean 57.9). Indications for surgery were vertebrobasilar insufficiency in 24 (19%), extremity ischemia (EI) in 33 (27%), transient ischemic attacks (TIAs) in 13 (11%), both vertebrobasilar insufficiency and EI in 31 (25%), and both TIAs and EI in 23 (18%) patients. Graft conduits were polytetrafluoroethylene in 44 (35%) and Dacron in 80 (65%) cases. Concomitant ipsilateral carotid endarterectomy was done in 32 (26%) patients. During operation, death occurred in one patient (0.8%), and complications occurred in 10 (8%) patients. Thirty-day primary patency and symptom-free survival rates were 100%. Long-term follow-up ranging from 5 to 164 months was available for the 60 cases done between 1975 and 1990. Three grafts occluded at 30, 36, and 51 months after surgery for a primary patency rate of 95% at 5 and 10 years. Twenty-two patients died, yielding survival rates of 83% at 5 years and 59% at 10 years. Symptom recurrence occurred in six (10%) patients from 9 to 66 months after surgery. The symptom-free survival rate was 98% at 1 year, 90% at 5 years, and 87% at 10 years. Symptoms recurred in three patients with occluded grafts and three with patent grafts. The preoperative symptoms of drop attacks and TIAs did not recur. EI recurred in 5% and was noted only in the presence of graft occlusion. Dizziness recurred in 17% of patients admitted with this symptom and was observed despite graft patency. CONCLUSION: Carotid-subclavian bypass was a safe and durable procedure for relief of symptomatic occlusive disease of the subclavian artery. Long-term symptomatic relief appeared particularly likely in patients with drop attacks or upper extremity ischemia.

Adult↗
PubMed1994

Isolated symptomatic midcervical stenosis of the internal carotid artery.

All carotid arteriograms performed between January 1, 1986 and December 31, 1991 were reviewed for instances of midcervical carotid stenosis. Sixteen cases were identified. A stenosis related to the hypoglossal nerve was specifically identified in three operative reports in the retrospective review. Pathologic examinations of the specimens confirmed the presence of atherosclerotic plaque or fibrous dysplasia. In another case, relief of intermittent neurologic symptoms (TIAs) was obtained by division of the stylohyoid ligament. Prospective observation of five cases confirmed a stenosis immediately distal to a transverse neurofascial band formed by the hypoglossal nerve, which arose with the vagus nerve in three patients, and a large cervical contribution to the ansa hypoglossi in two. Presumably the lesion was caused by the turbulent flow in the internal carotid artery distal to the band. Isolated stenosis of the midcervical internal carotid artery unrelated to bifurcation disease may be the result of turbulence induced by tethering neural or myofascial bands.

Aged↗
PubMed1994

Quality control in ultrasound studies on atherosclerosis.

This review discusses the quality control of equipment and technician performance in long term, multicentre trials using ultrasound detection and quantification of atherosclerosis. Examples on how such quality control measures could be implemented are given. Based on our own experience and that of other groups we suggest the following items as being important when planning for quality control in this type of study. 1. Write down the specifications demanded with regard to the ultrasound equipment and reading stations. 2. Compare the commercially available equipment on those characteristics by means of in-vitro and/or in-vivo testing. 3. Select the most suitable equipment for all centres and check it before shipping. 4. Sign a full maintenance agreement for all centres. 5. Evaluate the ultrasound devices and reading stations regularly during the study using phantoms. 6. Train sonographer and readers thoroughly before the start of the study. Certify those who successfully complete the training programme and demonstrate proficiency in scanning or reading. 7. Determine each sonographer's/reader's variability before and repeatedly during the study. Give feedback on performance to the sonographer/reader. 8. Create a regular retraining programme for all sonographers/readers and extend for those with poor performance. 9. Feed all the above information to a Data Quality Control Committee, having the ultimate responsibility for the quality control in the study.

Arteriosclerosis↗
PubMed1994

Relation of carotid artery wall thickness to diabetes mellitus, fasting glucose and insulin, body size, and physical activity. Atherosclerosis Risk in Communities (ARIC) Study Investigators.

BACKGROUND AND PURPOSE: We tested the hypothesis that body mass, waist-to-hip circumference ratio, physical inactivity, diabetes, hyperglycemia, and fasting insulin are each positively associated with asymptomatic carotid artery wall thickness. METHODS: Average intimal-medial carotid wall thickness (an indicator of atherosclerosis) was measured noninvasively by B-mode ultrasonography in cross-sectional samples of 45- to 64-year-old adults, both blacks and whites, free of symptomatic cardiovascular disease, in four US communities. RESULTS: Sample mean carotid wall thickness was approximately 0.7 mm in women (n = 7956) and 0.8 mm in men (n = 6474). Body mass, waist-to-hip ratio, work physical activity, diabetes, and fasting insulin were associated (P < .05) with carotid wall thickness in the hypothesized direction. Adjusted for age, race, smoking, body mass index, artery depth, and Atherosclerosis Risk in Communities field center, mean wall thickness was greater by 0.02 mm in women and 0.03 mm in men for a 0.07-unit (one SD) larger waist-to-hip ratio. Adjusted mean wall thickness was about 0.07 mm thicker in participants with diabetes mellitus and 0.02 mm thicker in participants with hyperglycemia (fasting glucose 6.4 to 7.7 mmol/L) than in subjects with fasting glucose < 6.4 mmol/L. Adjusted mean wall thickness increased by about 0.02 mm with an increase of 100 mmol/L in fasting serum insulin. CONCLUSIONS: Abdominal adiposity, physical inactivity, and abnormal glucose metabolism are associated positively with carotid intimal-medial wall thickness, suggesting these factors contribute to atherogenesis.

Aging↗
PubMed1994

Sympathectomy: quo vadis?

This paper reviews the evolution of sympathectomy in the management of vascular disease, hyperhidrosis and reflex sympathetic dystrophy over the past 26 years. The average general surgery resident has never been exposed to the procedure. The author feels that sympathectomy should be part of the armamentarium of vascular surgeons. An understanding of physiologic screening tests is necessary for the proper selection of patients who may benefit from sympathectomy. There has been a progressive decline in the number of publications on sympathectomy during this period. While the procedure is less commonly performed for vascular disease, sympathectomy remains a useful treatment for uncontrolled hyperhidrosis and for reflex sympathetic dystrophy.

Humans↗
PubMed1993

The Residency Review Committee for Surgery and the training of vascular surgeons.

PURPOSE: This article reviews the activities and actions of the Residency Review Committee (RRC) for Surgery in the accreditation process of of vascular surgery training programs since 1983. METHODS: The substantial changes of the Special Requirements for Graduate Education in General Vascular Surgery are discussed for 1983, 1987, 1989, and 1992. The rank-ordered list of RRC citations is reviewed. The national resident operative statistics for the past 4 years are reported for both general and vascular surgery residents. RESULTS: Changes in the Special Requirements have included deletion of two of the four types of programs, elimination of the need for institutional programs in specialties other than core general or thoracic surgery, and relaxation of the restriction against concurrent resident assignment. The most common citation continues to be the negative impact on general surgery residents. Nevertheless national operative statistics show a favorable increase in case load for both general and vascular surgery residents. CONCLUSIONS: Future challenges to surgical education and practice are summarized; the solutions to these challenges will require cooperative efforts of the RRC, the American Board of Surgery, and a number of specialty societies and credentialing or regulatory bodies.

Accreditation↗
PubMed1993

Alcohol consumption and ultrasonographically assessed carotid artery wall thickness and distensibility. The Atherosclerosis Risk in Communities (ARIC) Study Investigators.

BACKGROUND: Although much has been written in recent years about the relation between alcohol and atherosclerotic disease, controversy exists as to whether and how alcohol exerts an effect on atherosclerosis in different sites. METHODS AND RESULTS: We tested the hypothesis that alcohol consumption is associated inversely with carotid atherosclerosis in a population sample of 45- to 64-year-old men and women who participated in the Atherosclerosis Risk in Communities (ARIC) Study and were free of cardiovascular disease at a baseline examination in 1987 to 1989. B-mode ultrasonography was used to determine carotid artery intimal-medial wall thickness and distensibility as indices of the degree of atherosclerosis. The level of alcohol consumption in the ARIC sample was generally low. Age-adjusted mean values of alcohol consumed (grams per week) were 72.0 for white and 74.3 for nonwhite men and 24.8 for white and 11.2 for nonwhite women. After adjustments for age, artery depth, education, body mass index, sport index, cigarette-years of smoking, low-density lipoprotein cholesterol, and diabetes mellitus, there was no significant cross-sectional association of reported current alcohol intake with either carotid artery wall thickness (among white and nonwhite men and nonwhite women) or distensibility (in any of the four sex-race groups). Among white women, the adjusted mean value of carotid artery wall thickness tended to be higher in light to moderate drinkers than in never or rare drinkers, but the difference across drinking status categories was of borderline statistical significance (P = .04) and may be of little biological importance. CONCLUSIONS: The ARIC Study found no material cross-sectional association between current alcohol intake and carotid atherosclerosis but provides an opportunity in the future to study atherosclerosis progression and incident events in relation to alcohol consumption in a large population sample of men and women.

Alcohol Drinking↗
PubMed1993

Current challenges in peripheral vascular surgery: traditions in transition.

The field of peripheral vascular surgery is changing as a result of many forces, including altered disease demographics, advances in technology, encroachment by competing specialties, evolution of training programs, governmental and reimbursement controls, and changing public expectations. The gradual evolution of program content of the annual meetings of the North American Chapter of The International Society for Cardiovascular Surgery for the past 20 years and the challenges for the future of vascular surgery in the USA are reviewed. During the past 20 years, 455 scientific papers and 20 presidential addresses were delivered to the North American Chapter. Papers on peripheral arterial and cerebrovascular disease have remained constant in number. Venous and cardiac contributions have declined in number and are covered in other societal meetings. Vascular radiologic interventions, diagnostic technology and research presentations have filled the void. Other topics, including epidemiology, manpower, outcomes, economics and governmental relations, have increased in number. The presidential addresses, while including topics of historical and clinical interest, have increasingly emphasized educational and socioeconomic issues. Vascular surgery, like other disciplines, is a dynamic specialty. As with medicine in general in the USA, this specialty will be increasingly challenged by socioeconomic pressures, which will lead to new issues that have not previously been addressed in the Chapter program, including preventive medicine and health services research.

Curriculum↗
PubMed1993

Vascular surgery: the burr under the saddle.

A decade ago vascular surgery "came of age" with formalization of accreditation of training programs and certification of subspecialists in the field. These events created turbulence in general surgery, with initial resistance to further subspecialization and fragmentation of the specialty. Subsequent reassessment of the trends in general surgery and its subspecialty disciplines has led to a reaffirmation of the integrity of the parent specialty. Recent proposals for reforms in resident training in general surgery and its subspecialties are currently being evaluated. Despite the current rapprochement between general and vascular surgery, many challenges remain for both disciplines. All surgeons, regardless of specialty, should broaden their respect for both "microscience," particularly molecular biology, and "macromedicine," including epidemiology, preventive medicine, and health services research.

Accreditation↗