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Biomedical subjects

J Amerena

Publications and source records attributed to J Amerena.

17 recordsLinked to original sources
PubMed2002

Heritability of left atrial size in the Tecumseh population.

BACKGROUND: Little is known about the determinants of atrial size, and no study has analyzed whether genetic factors are involved in the pathogenesis of LA enlargement. MATERIALS AND METHODS: We studied the heritability of echocardiographic left atrial size in 290 parents from the Tecumseh Blood Pressure Study and 251 children from the Tecumseh Offspring Study. All data from the parents and children were obtained at the same field office in Tecumseh, USA. Left atrial dimension was determined echocardiographically in accordance with American Society of Echocardiography guidelines with the use of leading-edge-to-leading-edge measurements of the maximal distance between the posterior aortic root wall and the posterior left atrial wall at end systole. RESULTS: For correlation between the left atrial dimensions of the parents and their offspring, several models were generated to adjust the atrial dimensions in both groups for an increasing number of clinical variables. After removing the effect of age, gender, height, weight, skinfold thickness, and systolic blood pressure, parent-child correlation for left atrial size was 0.19 (P = 0.007). Further adjustment for left ventricular mass and for measuring left ventricular diastolic function increased the correlation to 0.25 (P = 0.001). CONCLUSIONS: The present data indicate that heredity can explain a small but definite proportion of the variance in left atrial dimension.

Adolescent↗
PubMed2001

Genetic contribution to the variance in left ventricular mass: the Tecumseh Offspring Study.

OBJECTIVE: To estimate the contribution of heredity to the variance in left ventricular mass (LVM), and to ascertain whether genetic factors may interact with non-genetic factors in promoting LVM growth. SUBJECTS AND SETTING: The study population consisted of 290 healthy parents and 251 healthy children living in Tecumseh, Michigan, USA. MAIN OUTCOME MEASURE: Correlation of parents' LVM with offspring's LVM adjusting for a number of clinical variables. METHODS: LVM in parents and offspring was measured with M-mode echocardiography by the same investigators. RESULTS: Parents unadjusted LVM was unrelated to offspring unadjusted LVM, but after removing the confounding effect of age, sex, anthropometric measurements, systolic blood pressure, plasma insulin and urinary sodium excretion, parent-child correlation for LVM was 0.28 (P = 0.006). The relative contribution of parental-adjusted LVM and of several offspring phenotypic and environmental variables on offspring LVM was evaluated by multivariable regression analysis. When age, gender, anthropometric measurements and systolic blood pressure were accounted for, adjusted LVM of parents explained only 1.6% of the total variance in offspring LVM. However, after inclusion of insulin and urinary sodium in the model heredity explained 7.6% of the total variance in offspring LVM, and its predictive power was second only to that of child's height. Furthermore, an interactive effect of parental LVM with offspring systolic blood pressure was found on child's left ventricular mass. CONCLUSION: Heredity can explain a small, but definite proportion of the variance in LVM. Higher blood pressure favors the phenotypic expression of the genes that regulate LVM growth.

Adolescent↗
PubMed2000

Aortic dissection associated with Campylobacter aortitis.

Infective aortitis and associated mycotic aneurysms are uncommon clinical entities and most reported cases are associated with Salmonella species. We report successful surgical and medical treatment of a mycotic aneurysm of the aorta which presented as acute pericarditis and may have been caused by Camplyobacter jejuni.

Journal Article↗
PubMed2000

Determinants of left ventricular structure and mass in young subjects with sympathetic over-activity. The Tecumseh Offspring Study.

OBJECTIVE: In this study, we tested the hypothesis that sympathetic over-activity may cause metabolic abnormalities and affect left ventricular (LV) structure and mass early in life. SUBJECTS AND SETTING: The study population consisted of 111 healthy adolescents and young adults living in Tecumseh, Michigan (USA). MAIN OUTCOME MEASURES: Correlations of LV mass and structure with several clinical variables in relation to the activity of the sympathetic nervous system. METHODS: Power spectrum density estimates of heart rate variability were calculated with an auto-regressive method, and subjects were divided by cluster analysis into two groups according to low-frequency and high-frequency components. LV data were obtained by echocardiographic assessment RESULTS: Subjects with signs of sympathetic over-activity (n = 38, group 1) had higher heart rate, blood pressure (BP), waist/hip ratio and cholesterol levels than the rest of the group (n = 73, group 2). In group 1 subjects, insulin emerged as the strongest univariate correlate of interventricular septum and posterior wall thicknesses (P< 0.001 for both) and of LV mass (P= 0.009). These relationships remained significant when body mass index was accounted for. By contrast, the marginal univariate relationship with diastolic BP did not remain significant in multivariate analysis. In group 2 subjects, BP was strongly correlated with LV wall thickness and mass both in univariate (P values from 0.03 to < 0.001) and multivariate analyses, while insulin was not. The interactive effect of sympathetic activity and insulin on echocardiographic data was confirmed by multivariate analyses performed in the subjects grouped together (P values from 0.02 to 0.001 for the sympathetic activity x insulin interaction term). CONCLUSIONS: In young subjects with heightened sympathetic activity and initial metabolic abnormalities, insulin is a strong determinant of LV wall thickness and geometry, while in subjects with normal autonomic nervous system activity, the main determinant of left ventricular size is the haemodynamic load.

Adolescent↗
PubMed1999

Parental hyperdynamic circulation predicts insulin resistance in offspring: The Tecumseh Offspring Study.

Controversy surrounds the pathogenetic mechanisms of the relationship between hyperdynamic circulation and insulin resistance. Two hundred eight children and young adults (mean age, 17.2+/-3.0 years; range, 11 to 26 years) from the Tecumseh Offspring Study whose parents had been assessed with Doppler echocardiography at the age of 34 years during the previous Tecumseh Blood Pressure Study were considered for this analysis. Offspring data were stratified according to tertiles of parental cardiac index. Parents in the top cardiac index tertile had increased heart rate (P=0.001), stroke volume (P=0.0001), left ventricular fractional shortening (P=0.02), and plasma epinephrine (P=0.02) compared with parents in the other tertiles. Body mass index (BMI) and blood pressure were similar in all groups. Offspring of parents with a high cardiac index had greater BMI (P=0.001), skinfold thickness (P=0.008), and waist/hip ratio (P=0.02), higher diastolic blood pressure (P=0.02) and plasma insulin level (P=0.001), and higher heart rate during Stroop's color test (P=0.02) than offspring of parents with a lower cardiac index. In a multivariate regression analysis, offspring BMI was predicted by parental BMI and cardiac index (P=0.0001 and 0.003, respectively). The mother-child relationship explained most of the cardiac index-BMI association. In summary, parental hyperdynamic circulation was an important predictor of overweight, abnormal fat distribution, increased blood pressure, and hyperinsulinemia in offspring. Our results illustrate the complexity of interaction between a genetic tendency and its phenotypic expression. We speculate that the degree of beta-adrenergic responsiveness may be a major determinant of the phenotypic differences between the parents and offspring found in this study.

Adolescent↗
PubMed1998

Impact of ethnicity on left ventricular mass and relative wall thickness in essential hypertension.

This study was designed to evaluate the impact of ethnicity on left ventricular (LV) mass, and relative wall thickness in 527 patients (57% men, mean age 60 +/- 7 years) with mild to moderate high blood pressure. There were 63% Caucasians, 21% African-Americans, and 16% Hispanics. LV mass was indexed according to body surface area, height, and height to the allometric power of 2.7. Relative wall thickness included the 4 widely recognized patterns: normal, concentric remodeling, eccentric hypertrophy, and concentric hypertrophy. LV mass indexed to body surface area was similar among all 3 ethnic groups (Caucasians 117.1 g/m2, African-Americans 119.2 g/m2, Hispanics 122.7 g/m2); however, when indexed to height and height to the power of 2.7, Hispanics had slightly larger masses than the other 2 groups (Hispanics 168.1 and 73.3 g/m2.7 vs Caucasians 159.8 and 64.4 g/m2.7 [p = NS and p < 0.005]; and vs African-Americans 164.8 and 69.2 g/m2.7 [p = NS for both]). Using body surface area, the concentric remodeling was the predominant form of cardiac adaptation in Caucasians (36%) and African-Americans (42%), whereas the concentric hypertrophy pattern was 38% in Hispanics. Using indexing for both height and height to the power of 2.7, the concentric hypertrophy pattern predominated in all 3 ethnic groups (Caucasians 48% and 51%; African-Americans 68% and 66%; Hispanics 59% and 65%). In conclusion, because of the independent impact of weight on high blood pressure, LV mass adjusted to height or to height at the power of 2.7 should be reported in population studies. The concentric hypertrophy pattern--classic LV response to pressure overload conditions--is better represented when LV mass is indexed to height or to height to the allometric power of 2.7 than to body surface area.

Aged↗
PubMed1997

Comparison of left ventricular mass and geometric remodeling in treated and untreated men and women >50 years of age with systemic hypertension.

To investigate the effects of left ventricular (LV) mass and geometry in hypertensive patients >50 years of age, 540 men and women were divided into controlled, uncontrolled, and untreated groups. The high prevalence of concentric LV hypertrophy in postmenopausal women, despite medical therapy, emerged as a potentially important and underrecognized factor of their cardiovascular risk.

Aged↗
PubMed1997

Disparity between diastolic mitral flow characteristics and left ventricular mass in essential hypertension.

Because left ventricular (LV) hypertrophy and aging have been associated with abnormal LV relaxation, this study evaluated the impact of LV mass on the filling patterns derived by Doppler in a large population aged > or =50 years. Results suggest that in essential hypertension the intrinsic myocardial composition is more important than cardiac hypertrophy in determining LV diastolic properties. This apparent discrepancy between LV mass and diastolic filling patterns highlights the difficulty in establishing the diagnosis of diastolic dysfunction in elderly hypertensives.

Aged↗
PubMed1997

Role of left ventricular hypertrophy in diastolic dysfunction in aged hypertensive patients.

OBJECTIVE: To evaluate the influence of left ventricular hypertrophy (LVH) on the diastolic dysfunction in older hypertensive patients. METHODS: In total 665 patients (58% men, 61% White, aged 55-80 years) with mild-to-moderate essential hypertension underwent Doppler echocardiography. Data included left ventricular dimensions, left ventricular mass index, body mass index, E- and A-wave mitral flow velocities, E:A ratio, deceleration time > 150 ms), impaired relaxation (E:A ratio < 1.0, prolonged deceleration time according to age), and restrictive physiology (E:A ratio > 2.1, deceleration time < 150 ms)]. Data were distributed according to age (50-59, 60-69, and 70-80 years). RESULTS: The overall prevalence of sex-adjusted LVH in this study was 65%. When we compared hypertensive patients with and without LVH, the E- and A-wave velocities, E:A ratio, and deceleration time were similar. Moreover, the prevalences of normal, impaired relaxation, and restrictive physiology patterns among patients with and without LVH did not differ significantly (20, 79.5, and 0.5 versus 24, 75.5, and 0.5%). When the mitral flow patterns were adjusted according to age, the impaired relaxation pattern increased further with age (to 73% during the fifth decade, 83% during the sixth decade, and 88% during the seventh decade). CONCLUSIONS: LVH is not an independent factor associated with abnormal flow patterns in hypertensive patients aged over 50 years with normal systolic contractility. The impaired relaxation is the predominant pattern of diastolic dysfunction in older hypertensive patients and increases further with aging.

Aged↗
PubMed1997

Trends in left ventricular function over three years in the Tecumseh Study.

The relationship between blood pressure and left ventricular diastolic function was examined in participants of the Tecumseh Blood Pressure study. When subjects were divided into three blood pressure groups according to blood pressure levels 3 years apart, it was found that subjects who were had sustained "hypertension" at both time points (SH) had a decreased early/late diastolic filling rate (E/A ratio) compared to subjects who were hypertensive at only one of the timepoints (OH) and those who were consistently normotensive (NN) (1.71 +/- 0.02 NN vs 1.55 +/- 0.05 OH, (p < 0.0001) vs 1.56 +/- 0.07 SH, (p < 0.04)). This relative order was maintained when the second estimation of diastolic filling was performed 3 years later, but the E/A ratio had decreased significantly in all groups (1.54 +/- 0.01 NN vs 1.45 +/- 0.03 OH (p < 0.01) vs 1.37 +/- 0.06 SH (p < 0.006)), consistent with an age-related reduction in diastolic filling. Heart rates were significantly higher in the hypertensive groups initially (63.5 NN vs 66.2 OH (p < 0.03) vs SH 67.3 (p < 0.01)) and increased in all groups over time, with the largest increase in the SH group (64.9 +/- 0.04 NN vs 67.8 +/- 1.02 OH (p < 0.0001) vs 70.9 +/- 1.6 SH (p < 0.01)). Stroke volume index changed in all groups over time, with the increase greatest in the NN group and least in the SH groups the reverse of this pattern was seen for changes in heart rate. All subjects gained weight over the 3 years of the study so that these unexpected changes in stroke volume index and heart rate could be a consequence of a weight gain-related increase in the sympathetic tone, although we have no direct evidence that this is the case. Should this be so, the smaller increase in stroke volume in conjunction with the larger increase in the heart rate in the sustained hypertensive group may reflect the effects of mild blood pressure elevation in producing a reduction in left ventricular diastolic function associated with a decrease in the inotropic responsiveness of the heart to enhanced sympathetic tone.

Adolescent↗
PubMed1995

The role of the autonomic nervous system in hypertension.

The role of the autonomic nervous system in the genesis and maintenance of hypertension is becoming clearer with time. Early research suggested that increased vascular resistance in hypertension was not dependent on excess autonomic tone and thus it was presumed that the autonomic nervous system had little to do with hypertension. More recent studies have demonstrated that the initial hemodynamic abnormality in hyperkinetic borderline hypertension is "normal" vascular resistance, with an elevated cardiac optput and heart rate, associated with markers of increased sympathetic and decreased parasympathetic tone of central origin. Over time there is a transition to the high peripheral resistance and normal cardiac output hemodynamic state characteristic of established hypertension, which is due to the development of adaptive structural changes in the peripheral resistance vessels and heart. The autonomic abnormality in hypertension and subsequent vascular and cardiac changes may explain some of association between hypertension and risk factors for coronary heart disease. The autonomic imbalance found in hypertension may not be a chance occurrence and we postulate that it is due to the inheritance of the genes responsible for a more pronounced defense reaction, which in earlier times may have conferred a survival advantage but now permit the negative impact of this trait to become evident.

Adult↗
PubMed1994

Hematocrit levels and physiologic factors in relationship to cardiovascular risk in Tecumseh, Michigan.

OBJECTIVE: To investigate the relationship between hematocrit, blood pressure and other known cardiovascular risk factors. DESIGN: The Tecumseh Blood Pressure Study includes a cohort of subjects of average age 29.5 years (346 male, 277 female) who reside in Tecumseh, Michigan, USA. METHODS: The body weight; home, work and clinic blood pressures; hematocrit level, plasma renin activity, baseline and mentally stimulated plasma catecholamines level; and fasting glucose, insulin and lipids levels were obtained. Since menstruation and childbearing affect the hematocrit, results are presented only for males. The males in Tecumseh were divided into tertiles of hematocrit (group I < or = 43.25, group II 43.26-45.2 and group III > 45.2%). RESULTS: Higher hematocrit levels were significantly related to higher blood pressures at home, at work and in the clinic, although all of the values measured were within the normotensive range (128/79 mmHg clinic blood pressure in group III). The metabolic factors weight, cholesterol, triglycerides, insulin and glucose levels were significantly elevated in group III. The weight affected only the relationship of hematocrit to plasma insulin levels and not the other variables including the blood pressure. Groups II and III showed signs of sympathetic overactivity; their plasma renin levels, heart rates and norepinephrine levels after mental stimulation were elevated. CONCLUSIONS: Although the relationship of blood pressure to the hematocrit level was previously known, in Tecumseh hematocrit is also found to be associated with several other cardiovascular risk factors and with signs of a hypersympathetic state. We intend to evaluate prospectively the relative prognostic significance of a higher hematocrit level versus the other associated risk factors.

Adult↗
PubMedDate not supplied

ABPM comparison of the anti-hypertensive profiles of telmisartan and enalapril in patients with mild-to-moderate essential hypertension.

In this multicentre, prospective, randomized, open-label, blinded-endpoint (PROBE) study, the efficacy of 12 weeks' treatment with once-daily telmisartan 40-80 mg and enalapril 10-20 mg was evaluated using ambulatory blood pressure monitoring (ABPM) in 522 patients with mild-to-moderate essential hypertension. Patients were titrated to the higher dose of study drug at week 6 if mean seated diastolic blood pressure (DBP) was > or = 90 mmHg. The primary endpoint was the change from baseline in ambulatory DBP in the last 6 h of the 24-h dosing interval after 12 weeks' treatment. Telmisartan and enalapril produced similar reductions from baseline in DBP and systolic blood pressure (SBP) over all ABPM periods evaluated (last 6 h, 24-h, daytime and night-time). Telmisartan produced a significantly greater reduction in mean seated trough DBP, measured unblinded with an automated ABPM device in the clinic, amounting to a difference of -2.02 mmHg (P < 0.01). A significantly greater proportion of patients achieved a seated diastolic response with telmisartan than enalapril (59% versus 50%; P < 0.05), also measured with the same ABPM device. Both treatments were well tolerated. Compared with telmisartan, enalapril was associated with a higher incidence of cough (8.9% versus 0.8%) and hypotension (3.9% versus 1.1%). Therefore, telmisartan may provide better long-term compliance and, consequently, better blood pressure control than enalapril.

Adult↗
PubMedDate not supplied

A clinical trial of the effectiveness of water as a conductive medium in electrocardiography.

A clinical trial was conducted in three hospitals to determine if common tap water is suitable for use as a conductive medium in electrocardiography (ECG). It compares two consecutive ECG recordings of 100 patients, the first recordings were obtained with water as the conductive medium, the second tracings used the electroconductive gel Redux Creme. Analysis involved comparison of the height of the R wave in lead V4 and tracing reports from a cardiologist 'blind' to the medium used. Results indicated that there was no statistically significant difference in the conductive ability of the two media. Analysis of the clinical performance of the media indicated that in 82% of the traces water was equal to or better than gel in clarity, and in 90% of traces water was equal to or better than gel in suitability for diagnosis. One implication of the study is the possibility of significantly reducing the cost of ECG procedures while ensuring the quality of tracings remains at a clinically acceptable level.

Electric Conductivity↗