Biomedical subjects

Gerardo Heiss

Publications and source records attributed to Gerardo Heiss.

At least 55 records · Page 3Linked to original sources

PubMed2005

Short-term repeatability of electrocardiographic spatial T-wave axis and QT interval.

Although ventricular repolarization abnormalities reflect arrhythmic susceptibility, few reliable tools exist to identify their presence. We investigated the repeatability of the spatial T-wave axis and QT interval from standard 12-lead electrocardiograms in 63 asymptomatic volunteers. Certified technicians used a standardized protocol to digitally record 2 electrocardiograms per participant at each of 2 visits separated by 1 to 2 weeks. Absolute paired differences within and between visits were 0.19 degrees and 0.90 degrees for the T-wave axis and 1.08 and 1.55 milliseconds for the QT interval, respectively. The intraclass correlation coefficients for the T-wave axis and QT interval were 0.87 and 0.86, respectively. The impact of repeated measurements on the precision of the QT-interval measurements was evaluated for a hypothetical clinical trial aimed at detecting a drug-induced QT prolongation. We conclude that the spatial T-wave axis is as repeatable a measure of ventricular repolarization as the QT interval.

Electrocardiography↗

PubMed2005

Quantitative trait loci for metabolic syndrome in the Hypertension Genetic Epidemiology Network study.

As part of the Hypertension Genetic Epidemiology Network study, genome scans were performed in two ethnicities on the categorical metabolic syndrome (MetS). Genome scans were performed also on the factor scores produced by factor analysis (quantitative MetS). Heritabilities were highest for the obesity-insulin (INS) factor and lowest for blood pressure (BP) and central obesity. Seventeen unique putative quantitative trait loci (QTLs) yielded logarithm of the odds ratio (LOD) scores in excess of 1.7, 8 for blacks and 9 for whites. Important QTL findings in whites included an LOD score of 3.19 on chromosome 15q15 for the BP factor, 3.08 on chromosome 8p23 for the lipids-INS factor, and 3.07 on chromosome 3p26 for the obesity-INS factor. In blacks, after excluding type 2 diabetics, important QTLs were identified, including an LOD score of 2.77 on 13p12 for the obesity-INS factor and 2.63 on chromosome 11q24 for the lipids-INS factor. Categorical MetS had lower results than quantitative MetS. Notably, several loci identified overlap with those identified in other studies for a single or group of traits. The most promising candidate loci on 11q24 for lipids-INS and 13p12 for obesity-INS in blacks, 8p23 for lipids-INS, 14q24 for obesity-INS, and 15q15 for BP in whites warrant further investigation.

Black People↗

PubMed2005

Association of criteria pollutants with plasma hemostatic/inflammatory markers: a population-based study.

To elucidate the health effects of air pollution, the short-term association of criteria pollutants (particles <10 microm in diameter [PM(10)], O(3), CO, NO(2), and SO(2)) with hemostatic and inflammatory markers were examined using a population-based sample of 10,208 middle-age males and females of the biracial cohort of Atherosclerosis Risk in Communities (ARIC) study. For each participant, we calculated the following pollutant exposures 1-3 days prior to the randomly allocated cohort examination date: PM(10), CO, NO(2), and SO(2) as 24-h averages, and O(3) as an 8-h average of the hourly measures. The hemostatic/inflammatory factors included fibrinogen, factor VIII-C, von Willebrand factor (vWF), albumin, and white blood cell count (WBC). Linear regression models were used to adjust for cardiovascular disease (CVD) risk factors, demographic and socioeconomic variables, and relevant meteorological variables. One standard deviation (SD) increment of PM(10) (12.8 microg/m(3)) was significantly (P < 0.05) associated with 3.93% higher of vWF among diabetics and 0.006 g/dl lower of serum albumin among persons with a history of CVD. One SD increment of CO (0.60 p.p.m.) was significantly (P < 0.01) associated with 0.018 g/dl lower of serum albumin. Significant curvilinear associations, indicative of threshold effects, for PM(10) with factor VIII-C, O(3) with fibrinogen and vWF, and SO(2) with factor VIII-C, WBC, and serum albumin were found. This population-based study suggest that the hemostasis/inmflammation markers analyzed, which are linked to higher risk of CHD, are associated adversely with environmentally relevant ambient pollutants, with the strongest associations in the upper range of the pollutant distributions, and in persons with a positive history of diabetes and CHD.

Air Pollutants↗

PubMed2005

The metabolic syndrome and 11-year risk of incident cardiovascular disease in the atherosclerosis risk in communities study.

OBJECTIVE: To assess the magnitude of the association between the National Cholesterol Education Program's Third Adult Treatment Panel Report (ATP III) definition of the metabolic syndrome and cardiovascular disease (CVD). RESEARCH DESIGN AND METHODS: Cox regression was used to estimate the relative risk of incident coronary heart disease (CHD) and stroke among 12,089 black and white middle-aged individuals in the Atherosclerosis Risk in Communities (ARIC) study. RESULTS: The metabolic syndrome was present in approximately 23% of individuals without diabetes or prevalent CVD at baseline. Over an average of 11 years of follow-up, 879 incident CHD and 216 ischemic stroke events occurred. Among the components of the metabolic syndrome, elevated blood pressure and low levels of HDL cholesterol exhibited the strongest associations with CHD. Men and women with the metabolic syndrome were approximately 1.5 and 2 times more likely to develop CHD than control subjects after adjustment for age, smoking, LDL cholesterol, and race/ARIC center (sex interaction P < 0.03). Similar associations were found between the metabolic syndrome and incident ischemic stroke. Comparison of receiver operating characteristic curves indicated that the metabolic syndrome did not materially improve CHD risk prediction beyond the level achieved by the Framingham Risk Score (FRS). CONCLUSIONS: Individuals without diabetes or CVD, but with the metabolic syndrome, were at increased risk for long-term cardiovascular outcomes, although statistical models suggested that most of that risk was accounted for by the FRS. Nevertheless, identification of individuals with the metabolic syndrome may provide opportunities to intervene earlier in the development of shared disease pathways that predispose individuals to both CVD and diabetes.

Arteriosclerosis↗

PubMed2005

Diabetes, glucose, insulin, and heart rate variability: the Atherosclerosis Risk in Communities (ARIC) study.

OBJECTIVE: To describe the progression of autonomic impairment among individuals with diabetes and pre-diabetic metabolic impairments. RESEARCH DESIGN AND METHODS: We investigated the consequence of diabetes and pre-diabetic metabolic impairments on the 9-year change in heart rate variability (HRV) in a population-based cohort of 6,245 individuals aged 45-64 years at baseline and cross-sectional associations among 9,940 individuals. RESULTS: Diabetic subjects had a more rapid temporal decrease in HRV conditional on baseline HRV than nondiabetic subjects. Adjusted mean annual changes (95% CI) (ms/year) in the SD of all normal-to-normal R-R intervals were -0.65 (-0.69 to -0.61) for those with normal fasting glucose vs. -0.95 (-1.09 to -0.81) for diabetic subjects, in root mean square of successive differences in normal-to-normal R-R intervals -0.35 (-0.39 to -0.30) vs. -0.66 (-0.82 to -0.51), and in R-R interval 6.70 (6.37-7.04) vs. 3.89 (2.72-5.05). While we found cross-sectional associations between decreased HRV and diabetes and nondiabetic hyperinsulinemia and a weak inverse association with fasting glucose, neither impaired fasting glucose nor nondiabetic hyperinsulimenia was associated with a measurably more rapid decline in HRV than normal. CONCLUSIONS: Cardiac autonomic impairment appears to be present at early stages of diabetic metabolic impairment, and progressive worsening of autonomic cardiac function over 9 years was observed in diabetic subjects. The degree to which pre-diabetic metabolic impairments in insulin and glucose metabolism contribute to decreases in cardiac autonomic function remains to be determined.

Arteriosclerosis↗

PubMed2004

Historical measures of social context in life course studies: retrospective linkage of addresses to decennial censuses.

BACKGROUND: There is evidence of a contribution of early life socioeconomic exposures to the risk of chronic diseases in adulthood. However, extant studies investigating the impact of the neighborhood social environment on health tend to characterize only the current social environment. This in part may be due to complexities involved in obtaining and geocoding historical addresses. The Life Course Socioeconomic Status, Social Context, and Cardiovascular Disease Study collected information on childhood (1930-1950) and early adulthood (1960-1980) place of residence from 12,681 black and white middle-aged and older men and women from four U.S. communities to link participants with census-based socioeconomic indicators over the life course. RESULTS: Most (99%) participants were linked to 1930-50 county level socioeconomic census data (the smallest level of aggregation universally available during this time period) corresponding to childhood place of residence. Linkage did not vary by race, gender, birth cohort, or level of educational attainment. A commercial geocoding vendor processed participants' self-reported street addresses for ages 30, 40, and 50. For 1970 and 1980 censuses, spatial coordinates were overlaid onto shape files containing census tract boundaries; for 1960 no shape files existed and comparability files were used. Several methods were tested for accuracy and to increase linkage. Successful linkage to historical census tracts varied by census (66% for 1960, 76% for 1970, 85% for 1980). This compares to linkage rates of 94% for current addresses provided by participants over the course of the ARIC examinations. CONCLUSION: There are complexities and limitations in characterizing the past social context. However, our results suggest that it is feasible to characterize the earlier social environment with known levels of measurement error and that such an approach should be considered in future studies.

Journal Article↗

PubMed2004

Prevalence of coronary heart disease and carotid arterial thickening in patients with the metabolic syndrome (The ARIC Study).

We determined the prevalence of the metabolic syndrome (MS) with the criteria recommended by the National Cholesterol and Education Program, Adult Treatment Panel III report and estimated the magnitude of cross-sectional associations between the MS, coronary heart disease (CHD), and atherosclerosis in 14,502 black and white middle-age patients in the Atherosclerosis Risk in Communities Study. CHD was ascertained by standardized procedures and subclinical atherosclerosis was determined by measuring carotid intimal medial wall thickness using B-mode ultrasonography. The prevalence of MS was 30%, with substantial variation across race and gender subgroups. Among women but not among men, MS was significantly associated with increasing low-density lipoprotein cholesterol. CHD prevalence was 7.4% among those with the MS compared with 3.6% in comparison subjects (p <0.0001). After adjustment for established risk factors, subjects who had MS were 2 times more likely to have prevalent CHD than were those who did not have the syndrome. Among individuals free of CHD and stroke, after adjustment for age, gender, and race/center, the average intimal-medial wall thickness of carotid arteries was greater among those with versus those without MS (747 vs 704 mum, p <0.0001). Thus, MS was significantly associated with the presence of CHD and carotid intimal medial wall thickness. Identification of patients who have MS may provide opportunities to initiate CHD prevention strategies.

Carotid Artery Diseases↗

PubMed2004

Accuracy and repeatability of commercial geocoding.

The authors estimated accuracy and repeatability of commercial geocoding to guide vendor selection in the Life Course Socioeconomic Status, Social Context and Cardiovascular Disease study (2001-2002). They submitted 1,032 participant addresses (97% in Maryland, Minnesota, Mississippi, or North Carolina) to vendor A twice over 9 months and measured repeatability as agreement between levels of address matching, discordance (%) between statistical tabulation areas, and median distance (d, in meters) and bearing (theta;, in degrees) between coordinates assigned on each occasion (H(o):Sigma(i)( = 1 -->) (n) [theta;(i) /n] = 180 degrees ). They also submitted 75 addresses of nearby air pollution monitors (77% urban/suburban; 69% residential/commercial) to vendors A and B and then measured accuracy by comparing vendor- and US Environmental Protection Agency (EPA)-assigned geocodes using the above measures. Repeatability of geocodes assigned by vendor A was high (kappa = 0.90; census block group discordance = 5%; d < 1 m; theta; = 177 degrees ). The match rate for EPA monitor addresses was higher for vendor B versus A (88% vs. 76%), but discordance at census block group, tract, and county levels also was, respectively, 1.4-, 1.9-, and 5.0-fold higher for vendor B. Moreover, coordinates assigned by vendor B were further from those assigned by the EPA (d = 212 m vs. 149 m; theta; = 131 degrees vs. 171 degrees ). These findings suggest that match rates, repeatability, and accuracy should be used to guide vendor selection.

Aged↗

PubMed2004

Evidence for a gene influencing fasting LDL cholesterol and triglyceride levels on chromosome 21q.

High levels of low-density lipoprotein (LDL) cholesterol, low levels of high-density lipoprotein (HDL) cholesterol, and high levels of triglycerides (TG) are strong predictors of cardiovascular disease risk. Motivated by previous evidence for pleiotropy between cholesterol and TG levels, we conducted bivariate linkage analysis of LDL cholesterol and TG concentration among participants of the Hypertension Genetic Epidemiolgy Network (HyperGEN), one of four networks in the NHLBI sponsored Family Blood Pressure Program Project. All available hypertensive siblings and their first-degree relatives were recruited. Both phenotypes were similarly adjusted for ethnicity, study center, sex, age, age-by-sex interactions, smoking, alcohol consumption, hormone use, diabetes medication use, and waist circumference. Variance component linkage analysis was performed as implemented in SOLAR, using ethnicity-specific marker allele frequencies derived from founders and multipoint IBDs calculated in MERLIN. A maximum genome-wide empirical LOD score of 3.9 was detected on chromosome 21 at 54cM, between markers D21S2055 and D21S1446. This signal overlaps with suggestive and/or significant linkages for total cholesterol, LDL cholesterol, and apolipoprotein B in three other studies and is suggestive of one or more genes on chromosome 21q jointly regulating LDL cholesterol and TG concentration.

Aged↗

PubMed2004

Prediction of ischemic stroke risk in the Atherosclerosis Risk in Communities Study.

The authors assessed the increase in the predictivity of ischemic stroke (IS) resulting from the addition of nontraditional risk factors and markers of subclinical disease to a basic model containing only traditional risk factors (current smoking, diabetes mellitus, systolic blood pressure, antihypertensive therapy, prior coronary disease, and left ventricular hypertrophy) among 14,685 middle-aged persons in the Atherosclerosis Risk in Communities Study. Participants were recruited from four US communities in 1987-1989. Risk prediction scores for IS through 2000 were estimated from Cox models. The ability to predict which persons would develop IS was assessed by means of the area under the receiver operating characteristic curve-the probability that persons with IS had a higher risk score than those without IS. Among 22 nontraditional factors considered, the joint addition of body mass index, waist:hip ratio, high density lipoprotein cholesterol, albumin, von Willebrand factor, alcohol consumption, peripheral arterial disease, and carotid artery wall thickness modestly and statistically significantly improved prediction of future IS over a risk score that included traditional factors. Further improvement was obtained by adding age and race. For women, the area under the receiver operating characteristic curve went from 0.79 to 0.83 to 0.84; for men, it went from 0.76 to 0.78 to 0.80. These modest improvements are not enough to influence clinical and public health efforts to reduce the community burden of IS.

Antihypertensive Agents↗

PubMed2004

Assessment of prolonged QT and JT intervals in ventricular conduction defects.

The JT interval or Bazett's QTc - QRS has been advocated for detection of prolonged repolarization in ventricular conduction defects (VCDs). However, the use of neither JT nor QTc - QRS has been validated, and normal limits for rate-adjusted JT have not been established for VCDs or for normal ventricular conduction. Functional relations among RR, JT, and QT intervals were evaluated in 11,739 adult men and women with normal ventricular conduction and in 1,251 subjects with major VCD. The results showed that JT adjustment obtained as QTc - QRS retained a strong residual correlation with ventricular rate (r = 0.54), making its use ill-advised. In contrast, QT adjustment as a linear function of the RR interval for VCD as QT(RR,QRS) = QT - 155 x (60/heart rate - 1) - 0.93 x (QRS - 139) + k, with k = -22 ms for men and -34 ms for women, removed the rate dependence and produced upper 2% and 5% normal limits at 460 and 450 ms, respectively, which are identical to those in normal conduction. As an alternative, equally effective linear JT adjustment formulas were derived, including newly required normal standards. Thus, detection of prolonged repolarization in VCD requires the use of the JT interval or a bivariate model for QT with RR and QRS intervals as covariates.

Adult↗

PubMed2004

Association of higher levels of ambient criteria pollutants with impaired cardiac autonomic control: a population-based study.

An association between air pollution and increased cardiovascular disease (CVD) mortality has been reported, but underlying mechanisms are unknown. The authors examined short-term associations between ambient pollutants (particulate matter less than 10 microm in aerodynamic diameter (PM10), ozone, carbon monoxide, nitrogen dioxide, and sulfur dioxide) and cardiac autonomic control using data from the fourth cohort examination (1996-1998) of the population-based Atherosclerosis Risk in Communities Study. For each participant, the authors calculated PM10 and gaseous pollutant exposures as 24-hour averages and ozone exposure as an 8-hour average 1 day prior to the randomly allocated examination date. They calculated 5-minute heart rate variability indices and used logarithmically transformed data on high-frequency (0.15-0.40 Hz) and low-frequency (0.04-0.15 Hz) power, standard deviation of normal R-R intervals, and mean heart rate. Linear regression was used to adjust for CVD risk factors and demographic, socioeconomic, and meteorologic variables. Regression coefficients for a one-standard-deviation increase in PM10 (11.5 microg/m3) were -0.06 ms2 (standard error (SE), 0.018), -1.03 ms (SE, 0.31), and 0.32 beats/minute (SE, 0.158) for log-transformed high-frequency power, standard deviation of normal R-R intervals, and heart rate, respectively. Similar results were found for gaseous pollutants. These cross-sectional findings suggest that higher ambient pollutant concentrations are associated with lower cardiac autonomic control, especially among persons with existing CVD, and highlight a putative mechanism through which air pollution is associated with CVD.

Air Pollutants↗

PubMed2004

Effects of conjugated equine estrogen in postmenopausal women with hysterectomy: the Women's Health Initiative randomized controlled trial.

CONTEXT: Despite decades of use and considerable research, the role of estrogen alone in preventing chronic diseases in postmenopausal women remains uncertain. OBJECTIVE: To assess the effects on major disease incidence rates of the most commonly used postmenopausal hormone therapy in the United States. DESIGN, SETTING, AND PARTICIPANTS: A randomized, double-blind, placebo-controlled disease prevention trial (the estrogen-alone component of the Women's Health Initiative [WHI]) conducted in 40 US clinical centers beginning in 1993. Enrolled were 10 739 postmenopausal women, aged 50-79 years, with prior hysterectomy, including 23% of minority race/ethnicity. INTERVENTION: Women were randomly assigned to receive either 0.625 mg/d of conjugated equine estrogen (CEE) or placebo. MAIN OUTCOME MEASURES: The primary outcome was coronary heart disease (CHD) incidence (nonfatal myocardial infarction or CHD death). Invasive breast cancer incidence was the primary safety outcome. A global index of risks and benefits, including these primary outcomes plus stroke, pulmonary embolism (PE), colorectal cancer, hip fracture, and deaths from other causes, was used for summarizing overall effects. RESULTS: In February 2004, after reviewing data through November 30, 2003, the National Institutes of Health (NIH) decided to end the intervention phase of the trial early. Estimated hazard ratios (HRs) (95% confidence intervals [CIs]) for CEE vs placebo for the major clinical outcomes available through February 29, 2004 (average follow-up 6.8 years), were: CHD, 0.91 (0.75-1.12) with 376 cases; breast cancer, 0.77 (0.59-1.01) with 218 cases; stroke, 1.39 (1.10-1.77) with 276 cases; PE, 1.34 (0.87-2.06) with 85 cases; colorectal cancer, 1.08 (0.75-1.55) with 119 cases; and hip fracture, 0.61 (0.41-0.91) with 102 cases. Corresponding results for composite outcomes were: total cardiovascular disease, 1.12 (1.01-1.24); total cancer, 0.93 (0.81-1.07); total fractures, 0.70 (0.63-0.79); total mortality, 1.04 (0.88-1.22), and the global index, 1.01 (0.91-1.12). For the outcomes significantly affected by CEE, there was an absolute excess risk of 12 additional strokes per 10 000 person-years and an absolute risk reduction of 6 fewer hip fractures per 10 000 person-years. The estimated excess risk for all monitored events in the global index was a nonsignificant 2 events per 10 000 person-years. CONCLUSIONS: The use of CEE increases the risk of stroke, decreases the risk of hip fracture, and does not affect CHD incidence in postmenopausal women with prior hysterectomy over an average of 6.8 years. A possible reduction in breast cancer risk requires further investigation. The burden of incident disease events was equivalent in the CEE and placebo groups, indicating no overall benefit. Thus, CEE should not be recommended for chronic disease prevention in postmenopausal women.

Aged↗

PubMed2004

Lipoprotein-associated phospholipase A2, high-sensitivity C-reactive protein, and risk for incident coronary heart disease in middle-aged men and women in the Atherosclerosis Risk in Communities (ARIC) study.

BACKGROUND: Measuring C-reactive protein (CRP) has been recommended to identify patients at high risk for coronary heart disease (CHD) with low LDL cholesterol (LDL-C). Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a proinflammatory enzyme associated primarily with LDL. METHODS AND RESULTS: In a prospective, case cohort study in 12 819 apparently healthy middle-aged men and women in the Atherosclerosis Risk in Communities study, the relation between Lp-PLA2, CRP, traditional risk factors, and risk for CHD events over a period of approximately 6 years was examined in a proportional hazards model, stratified by LDL-C. Lp-PLA2 and CRP levels were higher in the 608 cases than the 740 noncases. Both Lp-PLA2 and CRP were associated with incident CHD after adjustment for age, sex, and race with a hazard ratio of 1.78 for the highest tertile of Lp-PLA2 and 2.53 for the highest category of CRP versus the lowest categories. Lp-PLA2 correlated positively with LDL-C (r=0.36) and negatively with HDL-C (r=-0.33) but not with CRP (r=-0.05). In a model adjusted for traditional risk factors including LDL-C, the association of Lp-PLA2 with CHD was attenuated and not statistically significant. For individuals with LDL-C below the median (130 mg/dL), Lp-PLA2 and CRP were both significantly and independently associated with CHD in fully adjusted models. For individuals with LDL-C <130 mg/dL, those with both Lp-PLA2 and CRP levels in the highest tertile were at the greatest risk for a CHD event. CONCLUSIONS: Lp-PLA2 and CRP may be complementary in identifying individuals at high CHD risk who have low LDL-C.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed2004

Genome-wide linkage analyses for age at diagnosis of hypertension and early-onset hypertension in the HyperGEN study.

A genome-wide scan was performed to identify chromosomal regions related to age at diagnosis of hypertension and to early-onset hypertension in white and African American families from the Hypertension Genetic Epidemiology Network (HyperGEN). Age at diagnosis of hypertension was reported by participants at recruitment and standardized residuals adjusted for sex, study center, and body mass index were created. Participants were classified as having early-onset hypertension if their reported age at diagnosis was before 45 years in whites or before 35 years in African Americans. Variance component linkage analysis was performed for age at diagnosis and an affected sibpair linkage analysis was performed for early-onset hypertension, both implemented in GENEHUNTER. In whites, the heritability of diagnosis age was estimated to be 35% and the maximum LOD score was found on chromosome 1 at 123 cM (LOD = 1.48). The maximum LOD score for early-onset hypertension was located on chromosome 18 at 69 cM (LOD = 1.21). In African Americans, the heritability of age of diagnosis was estimated to be 42% and the maximum LOD scores were found on chromosome 4 at 120 cM (LOD = 2.44) and on chromosome 15 at 60 cM (LOD = 2.31). The maximum LOD for early-onset hypertension in African Americans was also on chromosome 4 at 153 cM (LOD = 2.05) and overlies the mineralocorticoid receptor. Although these results report modest LOD scores, several of these loci have been previously reported to be linked to hypertension and blood pressure, lending further support that genes related to the risk of hypertension may be at these loci.

Adult↗

PubMed2004

Smoking and diabetes differ in their associations with subclinical atherosclerosis and coronary heart disease-the ARIC Study.

Atherosclerosis, nearly universally present in major arteries of Western adults, is characterized in all affected arteries by cholesterol-laden plaques and consistently associated with blood cholesterol levels. Other risk factors are reported to have relatively stronger or weaker associations with different atherosclerotic manifestations, but such differences have never previously been quantified. Measuring them may offer fresh clues to atherogenic processes and their prevention. The Atherosclerosis Risk in Communities Study (ARIC) ascertained incident coronary heart disease (CHD) and measured subclinical atherosclerosis as carotid artery intimal medial thickness using ultrasound and as lower extremity arterial disease (LEAD) using ankle-brachial blood pressure index. Blood cholesterol was associated with all endpoints. When standardized against LDL cholesterol associations, diabetes and smoking showed substantially different strengths of associations with different endpoints. Relative to associations with LDL cholesterol: (1) smoking, but not diabetes, increased in its strength of association with the severity of the underlying arterial disease; (2) the diabetes and smoking associations with CHD were much stronger in women than men, a phenomenon which, the standardization pattern suggests, is due to a gender difference in CHD pathogenesis, possibly attributable to arteriolar differences.

Ankle↗

PubMed2004

Repeatability of heart rate variability measures.

Due to the sparse data on the repeatability of short and ultra-short term heart rate variability (HRV) measures, we measured the repeatability of common HRV measures derived from 10-second, 2-minute, and 6-minute recordings in 63 healthy men and women, aged 45-64, in Chapel Hill, North Carolina. Three 10-second and 2 six-minute heart rate recordings were obtained during each of 2 visits, separated by 1 to 2 weeks. We partitioned the measurement error into components and computed intraclass correlation coefficients using nested, random effects models. Repeatability improved with the length of recording: intraclass correlation coefficients were greater than 0.7 for 6-minute measures and 2-minute time domain measures and greater than 0.5 for 2-minute frequency domain measures. Repeatability of measures from 10-second records was lower, but improved considerably when the mean from 2 or 3 records was used. Correlations between the same measures from different length recordings were quite high. Our findings support the use of records of at least 5 minutes in length in epidemiological studies, in accordance with previous guidelines. Researchers using 10-second records should consider taking the mean of several recordings, when possible, or using statistical methods to correct for measurement error.

Electrocardiography↗

PubMed2004

Retinal microvascular abnormalities and renal dysfunction: the atherosclerosis risk in communities study.

Microvascular disease has been linked with renal dysfunction in patients with diabetes. The aim of this study was to examine the association of retinal microvascular abnormalities to renal dysfunction among participants of the Atherosclerosis Risk in Communities Study, a population-based investigation in four U.S. communities. At the third examination (1993 to 1995), retinal photography was performed and the presence of retinal microvascular abnormalities was documented using a standard grading protocol. Renal dysfunction was defined as an increase in serum creatinine of at least 0.4 mg/dl or a death or hospitalization as a result of chronic kidney disease between the second (1990 to 1992) and fourth (1996 to 1998) examinations. Among 10,056 people who were included in the study, 270 (2.7%) developed renal dysfunction. After controlling for age, gender, race, diabetes, BP, and other risk factors, individuals with retinopathy (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.4 to 2.8), microaneurysms (OR, 2.0; 95% CI, 1.3 to 3.1), retinal hemorrhages (OR, 2.6; 95% CI, 1.6 to 4.0), soft exudates (OR, 2.7; 95% CI, 1.6 to 4.8), and arteriovenous nicking (OR, 1.4; 95% CI, 1.0 to 1.9) were more likely to develop renal dysfunction than individuals without these abnormalities. Retinal microvascular abnormalities are associated with renal dysfunction, suggesting that common systemic microvascular processes may underlie the development of microvascular damage in the eye and kidneys.

Arteriosclerosis↗