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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.

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.

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.

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.