Showing papers by "Barbara V. Howard published in 1996"

Estimation of left ventricular chamber and stroke volume by limited M-mode echocardiography and validation by two-dimensional and doppler echocardiography

Abstract: This study has been designed to improve estimation of stroke volume from linear left ventricular (LV) dimensions measured by M-mode echocardiography, in symmetrically contracting ventricles. In experimental studies, the ratio of LV epicardial long/short axes "Z" is about 1.3. We measured systolic and diastolic epicardial long and short axes by 2-dimensional echocardiography in 115 adults with widely varying LV short-axis dimensions (LV end-diastolic dimension = 3.95 to 8.3 cm). In a learning series of 23 normotensive and 27 hypertensive subjects, Z(diastole) was 1.3 +/- 0.1 and Z(systole) = 1.2 +/- 0.1, similar to findings in experimental animals. Regression equations were developed by comparing LV volumes by M-mode and 2-dimensional echocardiography. In a test series (65 subjects), LV volumes were calculated using separate regression equations for end-diastolic volume ([LV end-diastolic dimension] 4.765 - 0.288 x posterior wall thickness]) and for end-systolic volume ([LV end-systolic dimension] [4.136 - 0.288 x posterior wall thickness]). Because the term 0.288 x wall thickness was only about 8% of the first term between brackets, the average wall thickness in the learning series was substituted in the Z-volume formulas applied to the test series: end-diastolic volume = (4.5 x [LV end-diastolic dimensions]2) and end-systolic volume = (3.72 x [LV end-diastolic dimension]2). The mean relative error produced with this simplified method was 0.9%. in diastole and 1.4% in systole. Compared with Teichholz' M-mode volume method, Z-derived end-diastolic volume in the test series was equally well related to 2-dimensional volumes (both r = 0.88), with a better intercept (1.5 vs -23 ml, p <0.001) and a slope closer to the identity line (1.1 vs 1.4). Similar results were found for systolic volumes. In a second test series of 1,721 American Indian participants in the Strong Heart Study without mitral regurgitation or segmental LV wall motion abnormalities, Doppler-derived LV stroke volume (70 +/- 14 ml/beat) was similarly predicted by the Z-derived method (r = 0.65, 70 +/- 11 ml/beat) and Teichholz formulas (r = 0.64, 72 +/- 13 ml/beat), but Z-derived volumes had a regression line significantly closer to the identity line (p <0.005). Thus, LV chamber and stroke volumes can be determined from M-mode LV diameters over a wide range of LV sizes and in epidemiologic as well as clinical populations. The performance of this new method appears better than that obtained using the Teichholz formula, with a formula that is easy to handle and makes calculation of LV volumes by pocket calculator possible, even from limited echocardiographic studies.

Hypertension in Adult American Indians: The Strong Heart Study

Abstract: Hypertension is a primary risk factor for cardiovascular disease in the United States. Although cardiovascular disease is the leading cause of death among American Indians, the prevalence of hypertension, its awareness and control, and its association with other cardiovascular disease risk factors and physiological variables have not been well studied in this population. The Strong Heart Study is a longitudinal study of cardiovascular disease and its risk factors in American Indians. Participants (2703 women and 1846 men) were members of 13 tribes in central Arizona, southwestern Oklahoma, and regions of South and North Dakota. At least 1500 individuals between 45 and 74 years of age participated from each center in a baseline clinical examination conducted between July 1989 and January 1992. The examination consisted of a personal interview and physical examination that included an oral glucose tolerance test and three consecutive blood pressure measurements. This study reports data from the baseline examination on the prevalence of hypertension and correlates of blood pressure. Results indicated that despite the high frequency of diabetes and obesity, prevalence rates of hypertension in Arizona and Oklahoma were similar to those in the US population in the Third National Health and Nutrition Examination Survey (NHANES III), and rates among South/North Dakota participants were significantly lower (P < .0001). Blood pressure was higher in individuals with diabetes (P < .0001) and was significantly correlated with age (P < .0001) and albuminuria (P < .0001) but only weakly related to obesity. There was no independent relation between blood pressure and insulin. Blood pressure seems to be less affected by obesity and hyperinsulinemia in American Indians compared with other populations. Nevertheless, hypertension should be aggressively treated and controlled in American Indians because it is a known precursor to morbidity and mortality associated with diabetes and cardiovascular disease.

Apolipoprotein E polymorphism in American Indians and its relation to plasma lipoproteins and diabetes. The Strong Heart Study.

Abstract: Apo E is an important genetic factor in the development of cardiovascular disease, which is the leading cause of death among American Indians. We investigated the occurrence of the apo E alleles and the relation between apo E polymorphism and blood lipoproteins and apoproteins in members of 13 American Indian communities in three geographic areas. The frequencies of the e2 alleles in American Indians are significantly lower than those in white Americans, with the lowest frequencies of e2 in American Indians who reside in Arizona. Levels of LDL cholesterol and apo B were highest in those with e4 and lowest in those with e2. Concentrations of HDL cholesterol and apo A-I, however, tended to be lowest in e4 and highest in e2. Concentrations of total and VLDL triglycerides were lowest in the e3 group and higher in groups e2 and e4. Differences in concentrations of LDL cholesterol, HDL cholesterol, apo B, and apo A-I with apo E polymorphism were greater in women than in men, and differences in total and VLDL triglyceride concentrations by apo E phenotype were greater in men. Relations of total and VLDL triglycerides with apo E phenotype were stronger in women after menopause. In addition, differences in nearly all lipid and apoprotein concentrations between postmenopausal women and premenopausal women were greater if they had e2. Relations between apo E phenotype and lipoproteins were seen in individuals with diabetes mellitus as well as in nondiabetics. Apo E was significantly related to glucose control in diabetic women; those with e3 had higher glucose and hemoglobin A1C concentrations. Our findings show that (1) American Indians have low frequencies of apo e2; (2) apo E phenotype can influence levels of VLDL, LDL, HDL, apo B, and apo A-I; (3) the associations of apo E polymorphisms with lipid parameters differ between men and women; and (4) the associations in women of apo E polymorphisms with lipid parameters are modified by menopausal status.

Adverse Effect of Pregnancy on High Density Lipoprotein (HDL) Cholesterol in Young Adult Women The CARDIA Study

Abstract: The authors analyzed data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study in order to examine associations between parity and lipoproteins. Of 2,787 women recruited in 1985-1986, 2,534 (91%) returned in 1987-1988 and 2,393 (86%) returned in 1990-1991 for repeat evaluations. Two-year change (1987-1988 to 1985-1986) in high density lipoprotein (HDL) cholesterol was significantly different among the parity groups. HDL cholesterol decreased in women who had their first pregnancy of at least 28 weeks duration during follow-up (mean +/- standard error, -3.5 +/- 1.2 mg/dl), and this change was significantly different from the increase in women parous at baseline who had no further pregnancies (2.5 +/- 0.3 mg/dl) and in nullipara (2.4 +/- 0.3 mg/dl). There was a nonsignificant trend for a greater decrease in HDL2 cholesterol fraction in the primipara compared with the other groups. The HDL cholesterol decrease remained significant after controlling for race, age, education, oral contraceptive use, and changes in body mass index, waist-hip ratio, physical activity, smoking status, and alcohol intake. Change in HDL cholesterol was also significantly different among the parity groups in analyses of pregnancies that occurred during the subsequent 3 years of follow-up. There were no differences for change in LDL cholesterol or triglycerides. Potential mechanisms for a detrimental effect of pregnancy on HDL cholesterol include hormonal, body composition, or life-style/behavioral changes.

Diabetes and Coronary Heart Disease in American Indians: The Strong Heart Study

Abstract: Coronary heart disease (CHD) is the leading cause of death among American Indians. However, information on the prevalence of CHD and its association with known risk factors is limited. The purpose of the Strong Heart Study is to quantify CHD and its risk factors among three geographically diverse groups of American Indians. The population consists of 4,549 adults between 45 and 74 years of age in 13 Indian communities in Arizona, Oklahoma, and South and North Dakota. The phase I examination (1989–1991) revealed very high prevalence rates of diabetes that ranged from 33 to 72% in men and women in the three centers. Prevalence rates of definite myocardial infarction (MI) and definite CHD were higher in men than in women in all three centers ( P < 0.0001) and in those with diabetes ( P = 0.002 and P = 0.0003 in women and men, respectively). Diabetes was associated with a relatively greater increase in prevalence of MI (prevalence rate = 3.8 vs. 1.9) and CHD (prevalence rate = 4.6 vs. 1.8) in women than in men. Logistic regression analysis indicated that the prevalence of CHD among American Indians was significantly related to age, diabetes, hypertension, albuminuria, percentage of body fat, smoking, high concentrations of plasma insulin, and low concentrations of HDL cholesterol. Lower prevalence rates of CHD were found in Arizona despite higher rates of diabetes, obesity, hypertension, and albuminuria; these lower rates may be in part related to lower smoking frequency and lower concentrations of total and LDL cholesterol. These findings from the baseline Strong Heart Study examination emphasize the relative importance of diabetes and its associated variables as risk factors for CHD among American Indian populations.

Risk factors for cardiovascular disease in individuals with diabetes. The Strong Heart Study.

Abstract: Coronary heart disease (CHD) is the leading cause of death among individuals with diabetes. However, information on CHD and its association with known risk factors in populations with high rates of diabetes is limited. The purpose of the Strong Heart Study is to quantify CHD and its risk factors among three geographically diverse groups of American Indians who have a high prevalence of diabetes. The study group consisted of 4549 adults between 45 and 74 years of age in 13 Indian communities in Arizona, Oklahoma, and South and North Dakota. Rates of diabetes ranged from 33% to 72% in men and women in the three centers. The prevalence rates of definite myocardial infarction (MI) and definite CHD were higher in man than in women in all three centers (P<0.0001) and higher in those with diabetes (P=0.002 andP=0.0003 in women and men, respectively). Diabetes was associated with a relatively greater increase in prevalence of MI (PR=3.8 vs 1.9) and CHD (PR=4.6 vs 1.8) in women than in men. Logistic regression analysis indicated that prevalent CHD was significantly related to age, diabetes, hypertension, albuminuria, percent body fat, smoking, high concentrations of plasma insulin, and low concentrations of high-density lipoprotein (HDL)-cholesterol. These findings from the baseline Strong Heart Study examination emphasize the relative importance of diabetes-associated variables as risk factors for CHD among populations with high rates of diabetes.

Major electrocardiographic abnormalities among American Indians aged 45 to 74 years (the strong heart study)

Abstract: As part of the Strong Heart Study assessment of prevalent cardiovascular disease in middle-aged to elderly American Indians, the prevalence of major Minnesota code electrocardiographic (ECG) abnormalities was assessed in 4,531 participants aged 45 to 74 years (59% women) in selected tribal communities in Arizona, South and North Dakota, and Oklahoma The overall prevalence of major ECG abnormalities was lowest in Arizona participants, (eg, definite ECG myocardial infarction in 03% vs 18% in the other centers), although nearly two thirds of them had diabetes One or more major ECG abnormality occurred in progressively more women (104% to 212%) and men (133% to 32%) (both p

Plasma lipids and lipoprotein concentrations among American Indians: comparison with the US population.

Abstract: Lipoprotein measurements from the Third National Health and Nutrition Education Survey were used to estimate the need to measure fasting lipid concentrations and offer dietary and drug interventions in the US population. In this review, we compare the distribution of the Third National Health and Nutrition Education Survey population (according to National Cholesterol Education Program guidelines) with a contemporary sample of lipoprotein measurements in 4549 American Indians. Compared with data from the former, relatively fewer American Indians have cholesterol levels greater than 240 mg dl-1 and a much larger proportion have 'desirable' cholesterol levels less than 200 mg dl-1. The above guidelines, dictating measurement of fasting lipoprotein concentrations and dietary or drug intervention, take into account age, presence of cardiovascular risk factors and levels of both HDL- and LDL-cholesterol. The proportion of American Indians requiring these interventions is somewhat at less than the Third National Health and Nutrition Education Survey population, even though the American Indian population in this comparison is generally older (45-74 years of age) than the Survey participants (20 to more than 75 years of age). We review the literature concerning lipoprotein measurements in other American Indian and ethnic population groups that are undergoing rapid changes in lifestyle. In general, cardiovascular risk factors, including lipoprotein concentrations, are accumulating. These factors suggest that the public health impact of coronary heart disease will increase as these populations undergo further lifestyle changes.

Diabetes and coronary heart disease in American Indians

Abstract: Coronary heart disease (CHD) is the leading cause of death among American Indians. However, information on the prevalence of CHD and its association with known risk factors is limited. The purpose of the Strong Heart Study is to quantify CHD and its risk factors among three geographically diverse groups of American Indians. The population consists of 4,549 adults between 45 and 74 years of age in 13 Indian communities in Arizona, Oklahoma, and South and North Dakota. The phase I examination (1989–1991) revealed very high prevalence rates of diabetes that ranged from 33 to 72% in men and women in the three centers. Prevalence rates of definite myocardial infarction (MI) and definite CHD were higher in men than in women in all three centers (P < 0.0001) and in those with diabetes (P = 0.002 and P = 0.0003 in women and men, respectively). Diabetes was associated with a relatively greater increase in prevalence of MI (prevalence rate = 3.8 vs. 1.9) and CHD (prevalence rate = 4.6 vs. 1.8) in women than in men. Logistic regression analysis indicated that the prevalence of CHD among American Indians was significantly related to age, diabetes, hypertension, albuminuria, percentage of body fat, smoking, high concentrations of plasma insulin, and low concentrations of HDL cholesterol. Lower prevalence rates of CHD were found in Arizona despite higher rates of diabetes, obesity, hypertension, and albuminuria; these lower rates may be in part related to lower smoking frequency and lower concentrations of total and LDL cholesterol. These findings from the baseline Strong Heart Study examination emphasize the relative importance of diabetes and its associated variables as risk factors for CHD among American Indian populations.