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Biomedical subjects

J F Polak

Publications and source records attributed to J F Polak.

At least 91 records · Page 5Linked to original sources
PubMed1994

Fixed low-dose versus adjusted higher-dose warfarin following orthopedic surgery. A randomized prospective trial.

Orthopedic patients are at a high risk for developing venous thromboembolism, yet only a fraction of eligible patients receive anticoagulation prophylaxis after hospital discharge. This pilot study compared the efficacy of a fixed 2 mg/d dose of warfarin versus an adjusted higher dose of warfarin for 1 month after discharge to prevent the development of proximal leg deep venous thrombosis among recently discharged orthopedic patients. After standard inhospital treatment with adjusted higher-dose warfarin and a predischarge leg ultrasound to exclude deep venous thrombosis, 96 orthopedic patients were randomized just prior to discharge to either fixed low-dose (n = 49) or adjusted higher-dose warfarin (n = 47). At the 6-week follow-up evaluation, ultrasonographically confirmed, asymptomatic, proximal leg deep venous thrombosis occurred in two patients (4%). Both patients were randomized to the fixed low-dose group, although one remained on adjusted higher-dose warfarin throughout the trial. No patient in either group developed major bleeding complications. Further studies should be undertaken to further test fixed low-dose warfarin for venous thromboembolic prevention in high-risk orthopedic patients.

Female↗
PubMed1994

Relation of smoking with carotid artery wall thickness and stenosis in older adults. The Cardiovascular Health Study. The Cardiovascular Health Study (CHS) Collaborative Research Group.

BACKGROUND: Cigarette smoking has been associated with increased risk of atherosclerotic diseases in hospital-based studies and in studies of middle-aged populations but not in population-based studies of older adults with and without clinical cardiovascular disease. METHODS AND RESULTS: We investigated the relation of smoking to carotid artery atherosclerotic disease, expressed as intimal-medial wall thickness and arterial lumen narrowing (stenosis) measured by ultrasound. Subjects were 5116 older adults participating in the baseline examination of the Cardiovascular Health Study, a community-based study of cardiovascular diseases in older age. With increased smoking there was significantly greater internal and common carotid wall thickening and internal carotid stenosis: current smokers > former smokers > never-smokers; for instance, the unadjusted percent stenosis was 24%, 20%, and 16%, respectively (P < .0001). A significant dose-response relation was seen with pack-years of smoking. These findings persisted after adjusting for other cardiovascular risk factors and were also confirmed when analyses were restricted to those without prevalent cardiovascular disease. The difference in internal carotid wall thickness between current smokers and nonsmokers was greater than the difference associated with 10 years of age among never-smoking participants (0.39 mm versus 0.31 mm). Among all participants, the prevalence of clinically significant (> or = 50%) internal carotid stenosis increased from 4.4% in never-smokers to 7.3% in former smokers to 9.5% in current smokers (P < .0001). CONCLUSIONS: These findings extend previous reports of a positive relation between smoking and carotid artery disease to a population-based sample of older adults using several different indicators of atherosclerotic disease.

Aged↗
PubMed1994

Correlates of blood pressure in community-dwelling older adults. The Cardiovascular Health Study. Cardiovascular Health Study (CHS) Collaborative Research Group.

Although elevated blood pressure is an important predictor of cardiovascular disease and stroke in the elderly, little information exists on the distribution and risk factor correlates of blood pressure in this group. As part of the Cardiovascular Health Study, a population-based cohort study of 5201 men and women aged 65 to 101 years, we investigated correlates of systolic and diastolic blood pressure. Multiple regression analyses were conducted for all participants and a subgroup of 2482 without coronary heart disease and not on antihypertensive therapy (the "healthier" subgroup). In the total group, independent predictors of diastolic blood pressure included heart rate, aortic root dimension, creatinine, hematocrit, alcohol use, and black race (positive associations) and internal carotid artery wall thickness, mitral early/late peak flow velocity, white blood cell count, cigarette smoking, and age (negative associations). Positive predictors of systolic blood pressure included mitral late peak flow velocity, left ventricular mass, common carotid artery wall thickness, serum albumin, factor VII, diabetes, alcohol use, and age; negative predictors were coronary heart disease, uric acid, height, and smoking. In the healthier subgroup, positive predictors of diastolic blood pressure included heart rate, hematocrit, serum albumin, creatinine, and body weight, whereas mitral early/late peak flow velocity, serum potassium, smoking, and age inversely related to diastolic pressure. For the same group, common carotid artery wall thickness, left ventricular mass, serum albumin, factor VII, high-density lipoprotein cholesterol, and age were directly related to systolic blood pressure, whereas serum potassium was inversely related. Both systolic and diastolic pressures varied considerably by geographic site.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Predictors of perceived health status in elderly men and women. The Cardiovascular Health Study.

Baseline data on the perceived health status of participants (N = 5,201) in the Cardiovascular Health Study of the Elderly (CHS) are reported. The authors examined the predictive utility of health-related factors representing eight different domains, assessed gender differences in the prediction of perceived health, and tested a hypothesis regarding the role of known clinical conditions versus subclinical disease in predicting perceived health. Multivariate analyses showed that the majority of the explained variance in self-assessed health is accounted for by variables that fall into four general categories. Although gender differences were small, the analysis showed that the relative importance of several predictor variables did vary by gender.

Aged↗
PubMed1993

Temporal patterns of antihypertensive medication use among elderly patients. The Cardiovascular Health Study.

OBJECTIVES: To estimate the incidence of newly treated hypertension and to describe the patterns of antihypertensive medication use among those aged 65 years and older. DESIGN: Medicare eligibility lists from four US communities (Forsyth County, North Carolina; Washington County, Maryland; Sacramento County, California; and Pittsburgh, Pa) were used to obtain a representative sample of 5201 community-dwelling elderly for the Cardiovascular Health Study, a prospective cohort study of risk factors for coronary heart disease and stroke. Participants were examined at baseline and again 1 year later. The two examinations included standardized questionnaires, blood pressure measurements, and the assessment of medication use by medication inventory. In this cohort analysis, we excluded 231 subjects (4.4%) who did not return for follow-up, 69 (1.3%) who had missing data for medications, and another 495 (9.5%) who were taking "antihypertensive" medications for an indication other than high blood pressure. INTERVENTIONS: None. RESULTS: Among the 4406 participants, 1613 used antihypertensive medications at both visits. Between the two visits, 144 started and 115 stopped antihypertensive therapy. Among nonusers at baseline, the annual incidence of newly treated hypertension was 5.2% in women and 5.6% in men. Due to the number of participants who stopped therapy, the overall prevalence of antihypertensive treatment increased only slightly, from 40.7% to 41.1% in women and from 37.1% to 38.2% in men, during 1 year of follow-up. After adjustment for age, systolic blood pressure, number of antihypertensive drugs, diabetes, and cardiovascular disease, the newly treated hypertensives were about half as likely as the previously treated hypertensives to receive diuretics (odds ratio [OR], 0.59; P = .008) or beta-blockers (OR, 0.52; P = .01); and they were about twice as likely to receive calcium channel blockers (OR, 1.88; P < .004) or angiotensin converting enzyme inhibitors (OR, 2.40; P < .001). A similar pattern of within-person changes over time was apparent among the continuous users. CONCLUSIONS: Between June 1990 and June 1991, physicians were increasingly prescribing angiotensin converting enzyme inhibitors and calcium channel blockers in place of diuretics and beta-blockers for the treatment of hypertension in elderly patients, especially for those just starting therapy.

Adrenergic beta-Antagonists↗
PubMed1993

Lower limb colour flow imaging: a comparison with ankle: brachial measurements and angiography.

Peripheral lower limb vascular disease represents a substantial health problem. Arteriography is currently the 'gold standard' imaging modality. However, much effort is presently being channeled towards alternative non-invasive techniques. To date, this involves mainly the interpretation of ankle: brachial pressure indices and segmental pressure measurements. A prospective pilot study of 20 patients (40 limbs) comparing these two techniques with colour Doppler ultrasound was carried out. Although ankle: brachial indices could accurately predict disease (sensitivity 100%, accuracy 92.5%), it failed to localize it; neither a high thigh: brachial index nor segmental drop could localize disease to the iliac (accuracy 70%) or femoro-popliteal (accuracy 55%) vessels respectively. Colour Doppler ultrasound correctly differentiated iliac from femoro-popliteal disease. It had an overall diagnostic accuracy of 90% in the femoral and popliteal vessels for both occlusion and stenosis and diagnosed 10 of 11 iliac lesions. Colour Doppler ultrasound has many advantages over pressure measurements in that it can both diagnose and localize arterial lesions accurately. We feel that using both techniques prior to angiography can accurately separate patients into either a surgical or angioplasty group. This may help utilize angiographic resources and radiologists' time more efficiently as well as reducing radiation dose to both patients and staff.

Adult↗
PubMed1993

Age-related trends in cardiovascular morbidity and physical functioning in the elderly: the Cardiovascular Health Study.

OBJECTIVE: To describe relationships between age and sub-clinical cardiovascular disease, manifest chronic disease, and physical functioning and limitations among persons aged 65 years and older, with emphasis on the "oldest old," those 85 years and older. DESIGN: Observational population-based study. SETTING: Four U.S. communities: Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Pittsburgh, Pennsylvania. PARTICIPANTS: 5,201 men and women aged 65 years and older. MEASUREMENTS: Demographic data; histories of cardiovascular disease (CVD), chronic lung disease, arthritis, diabetes, and hypertension; measures of subclinical disease including arm and ankle blood pressures, internal carotid wall thickness and stenosis, ejection fraction, left ventricular mass, fractional shortening, and diastolic function, electrocardiographic left ventricular hypertrophy and cardiac injury score, forced expiratory flow and volume; functional status including self-reported physical functioning, hearing and sight limitations and health status, and performance-based measures of function. These variables were examined among men and women in three age groups: 65-74 years, 75-84 years, and 85 + years. Subgroups of participants with and without manifest CVD were also examined. MAIN RESULTS: In women, the prevalence of CVD and other chronic conditions increased with age, and the highest rates occurred among those 85 years and older. In men, prevalence rates increased between the two younger groups, but the oldest group had lower than expected rates for coronary heart disease, cerebrovascular disease, hypertension, and chronic lung disease. In contrast, there were strong age-related linear trends in most of the subclinical measures of blood pressure, atherosclerosis and pulmonary function and in virtually all measures of functional status in both gender groups across the age range. There was a particularly marked decline in functional status between the two older age groups. While subclinical disease was greater and functional status was poorer among those with manifest CVD, with few exceptions, age-related trends were not significantly different between the two groups. CONCLUSIONS: Lower than expected prevalence rates of CVD among those aged 85 years and older, particularly among men, in this study of community-dwelling elderly may represent selection bias or a real plateauing in disease prevalence with age. However, subclinical disease appears to increase and functional status to decline across the age range in both men and women regardless of the presence of CVD. The apparent increase in subclinical disease with age indicates potential for CVD prevention after age 65.

Activities of Daily Living↗
PubMed1993

Carotid endarterectomy: preoperative evaluation of candidates with combined Doppler sonography and MR angiography. Work in progress.

Doppler sonography and magnetic resonance (MR) angiography were prospectively used in combination as a substitute for conventional angiography in 24 consecutive patients likely to undergo carotid endarterectomy. Of 19 patients (20 lesions) who underwent carotid endarterectomy, 18 had not undergone preoperative angiography. High-grade lesions (> 75%-diameter stenosis) were surgically confirmed in 16; a 60%-70% stenosis, in one; and subtotal occlusion of the internal carotid artery, in another. Angiography was performed in a case of suspected internal carotid artery dissection. In the five nonsurgical cases, no significant stenosis was noted with both techniques in two instances, total occlusion was seen in two cases, and an asymptomatic stenosis was seen in one. Follow-up (average, 4.5 months) showed one case of symptomatic occlusion of the internal carotid artery after endarterectomy. This preliminary study suggests that the combined use of Doppler sonography and MR angiography can, in up to 79% (15 of 19) of cases, replace angiography for the preoperative evaluation of patients likely to need carotid endarterectomy.

Aged↗
PubMed1993

Sonographic evaluation of carotid artery atherosclerosis in the elderly: relationship of disease severity to stroke and transient ischemic attack.

Doppler and real-time ultrasound (US) were performed to evaluate the extent of atherosclerotic changes in the carotid artery and to assess their relationship to prevalent cerebrovascular disease. Real-time US scans and Doppler measurements of the carotid arteries were analyzed in 5,201 subjects aged 65 years or older. Severity of atherosclerotic lesions was associated with increased frequencies of hyperechoic, irregular, and heterogeneous textured lesions (P < .0001). The severity of internal carotid artery stenosis was associated with thickening of the intima-media layer of the common carotid artery wall (r = .37, P < .0001). A history of stroke and transient ischemic attack (TIA) was more likely when hyperechoic, heterogeneous, and irregular lesions were seen in the carotid artery. Internal carotid artery stenosis correlated better with prevalent stroke and TIA than did sonographic descriptions of plaque texture. However, the prevalence of hyperechoic, heterogeneous, and irregular lesions increased as the degree of internal carotid stenosis increased. On real-time images alone, the average of the internal carotid artery maximal wall thickness is the sonographic measure of atherosclerosis that enables the best prediction of prevalent stroke and TIA.

Aged↗
PubMed1993

Intraarterial thrombolysis of lower extremity occlusions: prospective, randomized comparison of forced periodic infusion and conventional slow continuous infusion.

A prospective randomized controlled trial compared forced infusion (FI) of urokinase (UK) with conventional slow continuous infusion (CI) in 25 patients with 25 acutely ischemic lower limbs. Demographics, ischemia categories, and infusion rates and doses were similar for both groups. A preliminary single-pass bolus of UK was injected into the thrombus in all patients with a pulsed-spray technique, and heparin was administered. UK was then infused with a CI pump (n = 13) or a prototype pulsed-spray pump (n = 12). The primary end point was patency, defined as at least 95% thrombolysis by volume, with brisk antegrade flow occurring within 4 hours. Eleven of the 12 patients (92%) who underwent FI and nine of the 13 (70%) who underwent CI had patency within 4 hours. However, 10 patients who underwent FI and nine who underwent CI had residual thrombi prolonging infusion. No significant differences between the two groups were apparent in speed of lysis, initial success rates, complication rates, or 30-day clinical outcome. Lytic therapy, however, was completed within 24 hours in 18 of 23 (78%) successfully treated patients (P = .01).

Aged↗
PubMed1993

Relationship of arterial compliance to baroreflex function in hypertensive patients.

The objectives of this study were to determine whether carotid arterial compliance is reduced in patients with hypertension and to assess whether reduced arterial compliance is related to abnormal arterial baroreflex function. Accordingly, concurrent measurements of carotid arterial diameter (via computerized high resolution B-mode ultrasonography) and blood pressure were made to determine carotid arterial compliance in 23 normotensive and 16 age-matched hypertensive patients. In addition, arterial baroreflex function was assessed in 12 of the normal subjects and nine of the hypertensive patients by measuring the infusions of nitroprusside and phenylephrine. Compared with the normotensive subjects, the patients with hypertension had reduced compliance (5.9 +/- 0.7 vs. 16.6 +/- 1.8 10(-7) m2/kPa, mean +/- SE, P < 0.001). The baroreflex slope relating the change in R-R interval to the change in systolic blood pressure during the drug infusions was less in the hypertensive than normotensive subjects (12.3 +/- 2 vs. 18.9 +/- 2 ms/mmHg, P < 0.05). Consequently, when both normotensive and hypertensive subjects were considered, there was a significant correlation between the baroreflex slope and compliance (r = 0.53, P < 0.05). However, there was no correlation between the baroreflex slope and compliance within either the normotensive group (r = 0.04, P = NS) or the hypertensive group (r = 0.43, P = NS) when analyzed separately. There was a significant correlation between age and compliance (r = -0.48, P < 0.01) but not between age and baroreflex function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Detection and quantification of carotid artery stenosis: efficacy of various Doppler velocity parameters.

OBJECTIVE: The purpose of this study was to evaluate and compare the accuracies of the different Doppler velocity parameters used to grade stenoses of the carotid artery. MATERIALS AND METHODS: Seven velocity parameters determined with Doppler spectra were compared with angiographic findings in 138 carotid bifurcations: the peak systolic and peak end-diastolic velocities in the internal and common carotid arteries, the ratios of peak systolic and peak end-diastolic velocities between the internal and common carotid arteries, and the ratio of peak systolic velocity in the internal carotid artery to peak end-diastolic velocity in the common carotid artery. A receiver-operating-characteristic (ROC) analysis was performed, with and without correction for the bias introduced by preferentially selecting patients for angiography, if the Doppler results indicated a lesion. Multiple regression analysis was performed to predict the percent stenosis and to predict the probability of a 70% or greater stenosis. RESULTS: Of the Doppler parameters, the peak systolic velocity in the internal carotid artery and its ratio to the peak end-diastolic velocity in the common carotid artery were the most accurate and had equivalent test performance (ROC area = 0.94; after correction for verification bias, ROC area = 0.78). In multiple regression analysis, the peak systolic velocity in the internal carotid artery was the most significant parameter, although its ratio to the peak end-diastolic velocity in the common carotid artery had incremental value in detecting a 70% or greater stenosis, and the peak systolic velocity in the common carotid artery provided additional information for quantifying the stenosis. CONCLUSION: The peak systolic velocity in the internal carotid artery is the best single velocity parameter for quantifying a stenosis and for detecting a 70% or greater stenosis.

Bias↗
PubMed1993

Arterial sonography: efficacy for the diagnosis of arterial disease of the lower extremity.

Until recently, Doppler sonography played a minor role in the evaluation of peripheral arterial occlusive disease. Two recent developments have made sonographic evaluation of the arteries in the lower extremity more attractive. The introduction of color flow mapping significantly shortened the examination time, and the sonographic results were found to dramatically affect the treatment of patients with peripheral arterial disease. This review article describes the changing role of arterial sonography in patients with arterial disease of the lower extremity.

Arterial Occlusive Diseases↗
PubMed1993

Risks and benefits of femoropopliteal percutaneous balloon angioplasty.

PURPOSE: The purpose of this study was to evaluate the efficacy of angioplasty in the treatment of femoropopliteal arterial disease. METHODS: From 1980 to 1991, 126 angioplasty procedures were performed in 131 limbs of 106 patients with 175 femoropopliteal lesions (26 common femoral, 118 superficial femoral, and 31 popliteal). Critical ischemia was present in 55 limbs (42%), and claudication was present in 76 (58%). Angioplasty was performed for a single lesion in 87 limbs (66%) and for multiple lesions in 44 (34%). In 13 limbs (10%) the most severe lesion was an occlusion; in 118 (90%) all lesions were stenoses. Distal runoff was good (2 or 3 vessels patent) in 72 limbs (55%) and poor (0 or 1 vessel patent) in 59 (45%). RESULTS: Death within 30 days occurred in 0.8%, nonfatal systemic morbidity in 7.1%, and local morbidity in 1.6% of procedures. Multivariate analysis revealed that indication and age were predictive of increased morbidity and mortality rates. Immediate success was achieved in 95% of limbs treated. Mean follow-up time was 2.0 years. The overall 5-year cumulative primary patency rate was 45% (+/- 5%). In a proportional hazards model indication and lesion type were predictive (p < 0.01) of long-term failure, with relative risks of 2.0 (1.2 to 3.3) and 2.7 (1.3 to 5.6), respectively. The 5-year primary patency rate after angioplasty for stenoses and claudication was 55% (+/- 7%), for stenoses and critical ischemia it was 29% (+/- 11%), and for occlusions it was 36% (+/- 14%). CONCLUSION: These results suggest that femoropopliteal angioplasty is a low-risk procedure with acceptable long-term results in patients with claudication and stenoses.

Angioplasty, Balloon↗
PubMed1992

The distribution of coagulation factors VII and VIII and fibrinogen in adults over 65 years. Results from the Cardiovascular Health Study.

The Cardiovascular Health Study (CHS) was designed to examine cardiovascular disease and its risk factors in older adults. We report here the distributions of the coagulation factors fibrinogen, factor VII, and factor VIII in a population-based cohort of men and women 65 years or older. In other studies of middle-aged individuals, these factors were shown to be associated with cardiovascular risk. In the CHS cohort, all three factors were elevated, compared to levels reported in middle-aged individuals, and fibrinogen and factor VIII values were higher in each successive age group; factor VII values, in contrast, declined slightly with age in the CHS cohort. Compared to white subjects, blacks had higher values for fibrinogen and factor VIII and lower values for factor VII. While women had markedly higher values for factor VII and factor VIII than men at all ages in the CHS, mean fibrinogen values were not different between men and women.

Age Factors↗