Left ventricular mass and exercise responses predict future blood pressure. The Muscatine Study

Exaggerated Blood Pressure Response to Exercise Is a Risk of Future Hypertension Even in Healthy, Normotensive Young Individuals-Potential Preventive Strategies for This Phenomenon?

Physical activity and regular exercise are well known to reduce the risks of cerebrovascular and cardiovascular diseases, leading the American College of Sports Medicine to endorse the concept that "exercise is medicine". However, a single bout of exercise temporarily raises arterial blood pressure (BP) to meet the metabolic demands of working muscle, and this BP response is particularly exaggerated in older adults and patients with cardiovascular conditions, such as hypertension, resulting in an exaggerated BP response during exercise. This presents a paradox: while regular exercise is crucial for preventing these diseases, excessively high BP responses during exercise could increase the risk of vascular damage. The mechanisms underlying this exaggerated BP response during exercise remain unclear, and effective exercise regimens for these populations have yet to be established. Currently, low-intensity exercise is recommended; however, its efficacy in disease prevention is uncertain. Notably, even among healthy individuals, there is significant variation in the BP response to exercise. Some healthy individuals, despite having normal resting BP, exhibit an exaggerated BP response during physical activity. Importantly, these individuals are often unaware that their BP becomes excessively elevated during physical activity. Repeated exposure to these heightened BP responses through regular physical activity may increase their long-term risk of cardiovascular disease. How can we prevent disease development in these individuals while still ensuring the effectiveness of exercise? Some studies have shown that individuals with a family history of hypertension may experience this phenomenon even in children and adolescents. Additionally, left ventricular hypertrophy contributes to an exaggerated BP response to exercise, suggesting a possible genetic influence. Conversely, other reports indicate that factors such as arterial stiffness, obesity, and low exercise capacity also contribute to this exaggerated response. Our recent preliminary data suggest that the cognitive benefits of exercise may be diminished in individuals who exhibit an exaggerated BP response during exercise. This implies that individuals with an exaggerated BP response, despite having normal resting BP, may not fully benefit from exercise. In this perspective paper, we review the physiological aspects of this phenomenon and explore strategies to address it. Additionally, we discuss BP responses in athletes within this content. Our goal is to prevent disease while maximizing the benefits of exercise for healthy individuals with an exaggerated BP response, as well as for elderly and cardiovascular patients.

Inverse Association between Exercising Blood Pressure Response and Left Ventricular Chamber Size and Mass in Women Who Habitually Resistance Train

Exercise is a major modifiable lifestyle factor that leads to temporarily increased systolic blood pressure (SBP), which is thought to influence left ventricular mass normalized to body surface area (LVM/BSA). This relationship has never been studied in women who habitually perform resistance exercise.

PURPOSE

To determine if a direct correlation exists between the SBP response to resistance exercise (change from rest; eSBP) and LVM/BSA in young healthy women who habitually resistance train.

METHODS

Leg extension resistance exercise was performed while continuously monitoring blood pressure using finger plethysmography. LVM was estimated using echocardiography. Data are shown as mean ± SD.

RESULTS

Thirty-one women participated (age 23 ± 3 years, height 164 ± 7 cm, body mass 63.7 ± 10.3 kg). Resting SBP (110 ± 8 mmHg, r = 0.355, p = 0.049) was shown to be directly correlated to LVM/BSA (72.0 ± 28.4 g/m2). Conversely, eSBP (30.8 ± 14.6 ∆mmHg, r = -0.437, p = 0.014) was inversely related to LVM/BSA. eSBP was not correlated to interventricular septum width (0.88 ± 0.12 cm, r = -0.137, p = 0.463) or posterior wall thickness (0.91 ± 0.15 cm, r = -0.084, p = 0.654). eSBP was inversely related to left ventricle internal diameter during diastole (LVIDd) (4.25 ± 0.33 cm, r = -0.411, p = 0.021).

CONCLUSION

Counter to the hypothesis, these data suggest an inverse association between eSBP during resistance exercise and LVM/BSA in healthy young women who resistance train. This relationship is due to a smaller LVIDd with greater eSBP.

Impact of a family history of hypertension and physical activity on left ventricular mass

BACKGROUND

A positive family history of hypertension (FHH) (+FHH) is associated with elevated left ventricular mass (LVM). Regular physical activity (PA) may eliminate differences in LVM between +FHH and negative family history of hypertension (-FHH) adults. The aim of this study was to determine if a +FHH is associated with a greater LVM compared to a -FHH group within a sample of young, mostly active healthy adults with and without statistically controlling for PA.

METHODS

Healthy young (18-32 y) participants self-reported FHH status and habitual moderate and vigorous PA frequency. Participants then underwent an echocardiogram.

RESULTS

Of the 61 participants, 32 (M=11, W=21; non-active=8) reported -FHH and the remaining 29 (M=13, W=16; non-active=2) reported a +FHH. Mann-Whitney tests found the +FHH group had greater LVM (-FHH 129.5±41.8, +FHH 155.2±42.6 g, P=0.015) and LVM/body surface area (BSA) (-FHH 73.5±17.4, +FHH 88.4±17.3 g/m2, P=0.004). Separate ANCOVA models accounting for moderate and vigorous PA found that FHH status independently predicted LVM/BSA and PA frequencies were significant modifiers (ANCOVA controlling moderate PA: FHH status P=0.004, partial η2=0.133; moderate PA P=0.020, partial η2=0.089), (ANCOVA controlling vigorous PA: FHH status P=0.004, partial η2=0.132; vigorous PA P=0.007, partial η2=0.117).

CONCLUSIONS

This analysis suggests that physically active young adults with a +FHH have elevated LVM compared to their -FHH counterparts. This finding is independent of their habitual moderate and vigorous physical activity frequencies.

Blood pressure response to exercise in children and adolescents

Blood pressure changes during exercise are part of the physiological response to physical activity. Exercise stress testing can detect an exaggerated blood pressure response in children and adolescent. It is applied for certain clinical conditions, but is also commonly used as part of the assessment of athletes. The interpretation of blood pressure values in response to exercise during childhood and adolescence requires appropriate reference data. We discuss the available reference values and their limitations with regard to device, exercise protocol and normalization. While the link between an exaggerated blood pressure response and cardiovascular events and mortality has been demonstrated for adults, the situation is less clear for children and adolescents. We discuss the existing evidence and propose that under certain circumstances it might be reasonable to have children and adolescents undergo exercise stress testing as a rather non-invasive procedure to add additional information with regard to their cardiovascular risk profile. Based on the existing data future studies are needed to extend our current knowledge on possible links between the presence of certain clinical conditions, the detectability of an exaggerated blood pressure response during childhood and adolescence and the risk of developing cardiovascular morbidity and mortality in later life.

Prevalence, Predictors, Progression, and Prognosis of Hypertension Subtypes in the Framingham Heart Study

Background The epidemiology of hypertension subtypes has not been well characterized in the recent era. Methods and Results We delineated the prevalence, predictors, progression, and prognostic significance of hypertension subtypes in 8198 Framingham Heart Study participants (mean age, 46.5 years; 54% women). The prevalence of hypertension subtypes was as follows: nonhypertensive (systolic blood pressure [SBP] <140 mm Hg and diastolic blood pressure [DBP] <90 mm Hg), 79%; isolated systolic hypertension (ISH; SBP ≥140 mm Hg and DBP <90 mm Hg), 8%; isolated diastolic hypertension (SBP <140 mm Hg and DBP ≥90 mm Hg), 4%; and systolic-diastolic hypertension (SDH; SBP ≥140 mm Hg and DBP ≥90 mm Hg), 9%. The prevalence of ISH and SDH increased with age. Analysis of a subsample of nonhypertensive participants demonstrated that increasing age, female sex, higher heart rate, left ventricular mass, and greater left ventricular concentricity were predictors of incident ISH and SDH. Higher baseline DBP was associated with the risk of developing isolated diastolic hypertension and SDH, whereas higher SBP was associated with all 3 hypertension subtypes. On follow-up (median, 5.5 years), isolated diastolic hypertension often reverted to nonhypertensive BP (in 42% of participants) and ISH progressed to SDH (in 26% of participants), whereas SDH frequently transitioned to ISH (in 20% of participants). During follow-up (median, 14.6 years), 889 participants developed cardiovascular disease. Compared with the nonhypertensive group (referent), ISH (adjusted hazard ratio [HR], 1.57; 95% CI, 1.30-1.90) and SDH (HR, 1.66; 95% CI, 1.36-2.01) were associated with increased cardiovascular disease risk, whereas isolated diastolic hypertension was not (HR, 1.03; 95% CI, 0.68-1.57). Conclusions Hypertension subtypes vary in prevalence with age, are dynamic during short-term follow-up, and exhibit distinctive prognoses, underscoring the importance of blood pressure subphenotyping.

Assessment of diastolic blood pressure with the auscultatory method in children and adolescents under exercise conditions

Controversy surrounds whether to define resting diastolic blood pressure (DBP) as the onset of the fourth or fifth Korotkoff phase (K4, sound muffling, or K5, sound disappearance) in children and adolescents. Although undetectable in some children (due to sounds continuing to zero cuff pressure), K5 is currently recommended for consistency with adult practice and because K4 can be difficult to discern or undetectable. However, to our knowledge, no studies have specifically assessed the reliability of measuring DBP with K4 and K5 in children and adolescents under exercise conditions. We therefore measured DBP before and immediately after a Bruce protocol stress test in 90 children and adolescents aged 12.3 ± 3.5 years (mean ± SD) in a cardiology clinic setting. When detected, K4 and K5 were 63.5 ± 9.2 and 60.2 ± 12.6 mmHg, respectively, at rest and 59.2 ± 14.6 mmHg (p = 0.028 vs rest) and 52.9 ± 18.3 mmHg (p < 0.001), respectively, immediately post-exercise. K4 and K5 were not detected in 41% and 4% of participants at rest or in 29% and 37% post-exercise, respectively, while K5 resulted in unrealistic DBP values (<30 mmHg) in an additional 11%. Better exercise performance was associated with a more frequent absence of K5 post-exercise, and after excluding participants performing at <10th percentile for age, post-exercise K4 was absent in 23%, and plausible K5 values were not obtained in 59% (p < 0.001). Although neither K4 nor K5 alone were reliable measures of DBP immediately post-exercise, a novel hybrid approach using K4, if detected, or K5, if not, produced reasonable DBP measurements in 97% of participants.

Left ventricular geometry and risk of incident hypertension

OBJECTIVE

Left ventricular (LV) geometry change is an independent predictor for cardiovascular disease. However, data are equivocal on the association of echocardiographic parameters of LV geometry with incident hypertension. Thus, we were to investigate the risk of hypertension according to the baseline echocardiographic parameters of LV geometry.

METHODS

Study participants were 12 562 Koreans without hypertension who received echocardiography as an item of health check-up. They were divided into normotensive or prehypertensive group according to baseline blood pressure. In each group, study subjects were classified by quintiles of baseline echocardiographic parameters including left ventricular mass index (LVMI), relative wall thickness (RWT), interventricular septal thickness (IVST), posterior wall thickness (PWT) and IVST plus PWT and followed up for 5 years. Cox proportional hazards model was used in calculating adjusted HRs and their 95% CI for hypertension according to each quintile group. Area under the curve (AUC) analysis (AUC [95% CI]) was performed to compare the predictability of LVMI, RWT, IVST, PWT, IVST plus PWT for hypertension.

RESULTS

Prehypertensive group had the worse clinical and echocardiographic parameters in baseline analysis than normotensive group. The risk of hypertension significantly increased proportionally to baseline LVMI, RWT, IVST, PWI and IVST plus PWT above specific quintile levels, which was identified in both normotensive and prehypertensive group. In AUC analysis, IVST, PWT and IVST plus PWT showed a significantly increased AUC, compared with LVMI.

CONCLUSION

LV geometry change was significantly associated with the increased risk for hypertension in non-hypertensive individuals.

Submaximal exercise blood pressure and cardiovascular structure in adolescence

PURPOSE

Dynamic exercise results in increased systolic blood pressure (BP). Irrespective of resting BP, some individuals may experience exaggerated rise in systolic BP with exercise, which in adulthood is associated with risk of hypertension, and cardiovascular (CV) disease. It is unknown if exercise BP is associated with markers of CV structure during adolescence. We examined this question in a large adolescent cohort taking account of the possible confounding effect of body composition and BP status.

METHODS

4036 adolescents (mean age 17.8 ± 0.4 years, 45% male), part of a UK population-based birth cohort study completed a sub-maximal step-test with BP immediately post-exercise. Sub-samples underwent comprehensive echocardiography for assessment of cardiac structure; arterial structure including aortic pulse wave velocity (PWV) and carotid intima-media thickness; and assessment of body composition by dual-energy X-ray absorptiometry (DXA).

RESULTS

Each 5 mm Hg higher post-exercise systolic BP was associated with CV structure, including 0.38 g/m2.7 (95% CI: 0.29, 0.47) greater left-ventricular mass index (LVMI), and 0.04 m/s (95% CI: 0.03, 0.04) greater aortic PWV. Adjustment for age, total body fat, lean mass and BP status attenuated, but did not abolish associations with LVMI (0.14 g/m2.7 per 5 mm Hg of post-exercise systolic BP; 95% CI 0.21, 0.39) or aortic PWV (0.03 m/s per 5 mm Hg of post-exercise systolic BP; 95% CI: 0.02, 0.04).

CONCLUSION

Submaximal exercise systolic BP is associated with markers of CV structure in adolescents. Given the clinical relevance of exercise BP in adulthood, such associations may have implications for CV disease screening in young people and risk in later life.

2016 European Society of Hypertension guidelines for the management of high blood pressure in children and adolescents

Increasing prevalence of hypertension (HTN) in children and adolescents has become a significant public health issue driving a considerable amount of research. Aspects discussed in this document include advances in the definition of HTN in 16 year or older, clinical significance of isolated systolic HTN in youth, the importance of out of office and central blood pressure measurement, new risk factors for HTN, methods to assess vascular phenotypes, clustering of cardiovascular risk factors and treatment strategies among others. The recommendations of the present document synthesize a considerable amount of scientific data and clinical experience and represent the best clinical wisdom upon which physicians, nurses and families should base their decisions. In addition, as they call attention to the burden of HTN in children and adolescents, and its contribution to the current epidemic of cardiovascular disease, these guidelines should encourage public policy makers to develop a global effort to improve identification and treatment of high blood pressure among children and adolescents.

Impact of exaggerated blood pressure response in normotensive individuals on future hypertension and prognosis: Systematic review according to PRISMA guideline

PURPOSE

Arterial hypertension (aHT) is the leading risk factor for morbidity and mortality worldwide. Blood pressure (BP) deviation at rest is well defined and accompanies risk for cardiovascular events and cardiovascular mortality. A growing body of evidence emphasises that an exaggerated blood pressure response (EBPR) in cardiopulmonary exercise testing (CPET) could help to identify seemingly cardiovascular healthy and normotensive subjects, who have an increased risk of developing aHT and cardiovascular events in the future.

MATERIALS AND METHODS

The PubMed online database was searched for published studies reporting exercise-related BP and both the risk of aHT and cardiovascular events in the future.

RESULTS

We identified 18 original studies about EBPR in CPET, which included a total of 35,151 normotensive individuals for prediction of new onset of aHT in the future and 11 original studies with 43,012 enrolled subjects with the endpoint of cardiovascular events in the future. Although an EBPR under CPET is not well defined, a large number of studies emphasise that EBPR in CPET is associated with both new-onset aHT and cardiovascular events in the future.

CONCLUSIONS

A growing number of studies support the hypothesis that EBPR in CPET may be a diagnostic tool to identify subjects with an elevated risk of developing aHT and cardiovascular events in the future.

Left Ventricular Mass Indexing in Infants, Children, and Adolescents: A Simplified Approach for the Identification of Left Ventricular Hypertrophy in Clinical Practice

OBJECTIVE

To determine a simplified method to identify presence of left ventricular hypertrophy (LVH) in pediatric populations because the relationship between heart growth and body growth in children has made indexing difficult for younger ages.

STUDY DESIGN

Healthy children (n = 400; 52% boys, 0-18 years of age) from 2 different European hospitals were studied to derive a simplified formula. Left ventricular mass (LVM) was calculated according to the Devereux formula. The derived approach to index LVM was tested on a validation cohort of 130 healthy children from a different hospital center.

RESULTS

There was a strong nonlinear correlation between height and LVM. LVM was best related to height to a power of 2.16 with a correction factor of 0.09. Analysis of residuals for LVM/[(height(2.16)) + 0.09] showed an homoscedastic distribution in both sexes throughout the entire height range. A partition value of 45 g/m(2.16) was defined as the upper normal limit for LVM index. As opposed to formula suggested by current guidelines (ie, LVM/height(2.7)) when applying the proposed approach in the validation cohort of 130 healthy participants, no false positives for LVH were found (0% vs 8%; P < .01).

CONCLUSIONS

Our data support the possibility to have a single partition (ie, 45 g/m(2.16)) value across the whole pediatric age range to identify LVH, without the time-consuming need of computing specific percentiles for height and sex.

The effect of childhood obesity on cardiac functions

Obesity is a metabolic disorder defined as excessive accumulation of body fat, which is made up of genetic, environmental, and hormonal factors and has various social, psychological, and medical complications. Childhood obesity is a major indicator of adult obesity. The aim of this study is to evaluate the cardiac functions via electrocardiography (ECG), echocardiography (ECHO), and treadmill test in childhood obesity. A patient group consisting of 30 obese children and a control group consisting of 30 non-obese children were included in the study. The age range was between 8 and 17 years. Anthropometric measurements, physical examination, ECG, ECHO, and treadmill test were done in all patients. P-wave dispersion (PD) was found to be statistically significantly high in obese patients. In ECHO analysis, we found that end-diastolic diameter, end-systolic diameter, left ventricle posterior wall thickness, and interventricular septum were significantly greater in obese children. In treadmill test, exercise capacity was found to be significantly lower and the hemodynamic response to exercise was found to be defective in obese children. Various cardiac structural and functional changes occur in childhood obesity and this condition includes important cardiovascular risks. PD, left ventricle end-systolic and end-diastolic diameter, left ventricle posterior wall thickness, interventricular septum thickness, exercise capacity, and hemodynamic and ECG measurements during exercise testing are useful tests to determine cardiac dysfunctions and potential arrhythmias even in early stages of childhood obesity. Early recognition and taking precautions for obesity during childhood is very important to intercept complications that will occur in adulthood.

Association of diet and anthropometric measures as cardiovascular modifiable risk factors in young adults

Abstract Background: Cardiovascular accidents are the major cause of death in the developing world, accounting for nearly 40% of deaths in adult men and women. Developed countries have already brought this under control, whereas India has to take a giant leap. Diet plays a pivotal role among the various modifiable cardiovascular risk factors. The sole objective of this study is to point at nutrition as being the main modulator of different anthropometric parameters and directly or indirectly has a tremendous impact on the blood pressure levels even during young age. Methods: In a cross-sectional study involving 223 young adults, the pattern of food habits and level of physical activity were determined from self-reported questionnaires, while blood pressure, weight, height, waist circumference (WC), and hip circumference were measured, and body mass index (BMI) and waist-to-hip ratio (WHR) were computed. The subjects were grouped as normotensives and prehypertensives and also were compared according to their BMI and other parameters. Results: Statistically significant, greater association of weight followed by WC with the prehypertensive levels of blood pressure compared to other parameters was seen. The subjects detected as prehypertensives had predilection for salty, fried, oily, sweet, and fast food; BMI >25 kg/m2; and WC and WHR in high risk-categories per World Health Organization standards. More than 69% of subjects had high WHR, whereas only 9% of total subjects exercised regularly. Conclusions: Central obesity is associated with sedentary life and high intake of calories, leading to hypertension with advancing age. Early detection, awareness, and primary prevention would help reduce morbidity and mortality associated with cardiovascular diseases.

Lack of reduction of left ventricular mass in treated hypertension: the strong heart study

Background

Hypertensive left ventricular mass (LVM) is expected to decrease during antihypertensive therapy, based on results of clinical trials.

Methods and Results

We assessed 4‐year change of echocardiographic LVM in 851 hypertensive free‐living participants of the Strong Heart Study (57% women, 81% treated). Variations of 5% or more of the initial systolic blood pressure (SBP) and LVM were categorized for analysis. At baseline, 23% of men and 36% of women exhibited LV hypertrophy (LVH, P<0.0001). At the follow‐up, 3% of men and 10% of women had regression of LVH (P<0.0001 between genders); 14% of men and 15% of women, free of baseline LVH, developed LVH. There was an increase in LVM over time, more in men than in women (P<0.001). Participants whose LVM did not decrease had similar baseline SBP and diastolic BP, but higher body mass index (BMI), waist/hip ratio, heart rate (all P<0.008), and urinary albumin/creatinine excretion (P<0.001) than those whose LVM decreased. After adjusting for field center, initial LVM index, target BP, and kinship degree, lack of decrease in LVM was predicted by higher baseline BMI and urinary albumin/creatinine excretion, independently of classes of antihypertensive medications, and significant effects of older age, male gender, and percentage increase in BP over time. Similar findings were obtained in the subpopulation (n=526) with normal BP at follow‐up.

Conclusions

In a free‐living population, higher BMI is associated with less reduction of hypertensive LVH; lack of reduction of LVM is independent of BP control and of types of antihypertensive treatment, but is associated with renal damage.

Echocardiographic Characterization of Postnatal Development in Mice with Reduced Arterial Elasticity

PURPOSE

Decreased expression of elastin results in smaller, less compliant arteries and high blood pressure. In mice, these differences become more significant with postnatal development. It is known that arterial size and compliance directly affect cardiac function, but the temporal changes in cardiac function have not been investigated in elastin insufficient mice. The aim of this study is to correlate changes in arterial size and compliance with cardiac function in wildtype (WT) and elastin haploinsufficient (Eln^+/- ) mice from birth to adulthood.

METHODS

Ultrasound scans were performed at the ages of 3, 7, 14, 21, 30, 60, and 90 days on male and female WT and Eln^+/- mice. 2-D ultrasound and pulse wave Doppler images were used to measure the dimensions and function of the left ventricle (LV), ascending aorta and carotid arteries.

RESULTS

Eln^+/- arteries are smaller and less compliant at most ages, with significant differences from WT as early as 3 days old. Surprisingly, there are no correlations (R² < 0.2) between arterial size and compliance with measures of LV hypertrophy or systolic function. There are weak correlations (0.2 < R² < 0.5) between arterial size and compliance with measures of LV diastolic function.

CONCLUSIONS

Eln^+/- mice have similar cardiac function to WT throughout postnatal development, demonstrating the remarkable ability of the developing cardiovascular system to adapt to mechanical and hemodynamic changes. Correlations between arterial size and compliance with diastolic function show that these measures may be useful indicators of early diastolic dysfunction.

Impaired endothelial responses in apparently healthy young people associated with subclinical variation in blood pressure and cardiovascular phenotype

BACKGROUND

A phenomenon of endothelial impairment, independent of classical cardiovascular risk factors, has been observed in young people. We identified subjects with persistently reduced, or declining, endothelial function during adolescence and early adulthood, without apparent cardiovascular risk, and investigated the clinical relevance of this finding.

METHODS

Endothelial vasomotor responses were assessed by brachial artery flow-mediated dilatation (FMD) at age 15 years in 47 subjects (22 males) who returned for a repeated measurement at age 25. Subjects underwent quantification of left ventricular mass (LVM) and function by cardiovascular magnetic resonance, central arterial stiffness by applanation tonometry, and common carotid artery intima-media thickness using ultrasound on their visit at age 25.

RESULTS

Individuals with low average FMD over 10-year period, although normotensive, had 5 mm Hg higher systolic blood pressure and, significantly greater LVM (73.48 ± 7.73 vs. 56.25 ± 9.54 g/m(2), P = 0.0001), carotid intima-media thickness (cIMT) (0.53 ± 0.06 vs. 0.47 ± 0.04 mm, P = 0.03), and pulse wave velocity (5.97 ± 0.63 vs. 5.29 ± 0.59 m/s, P = 0.02) than those with higher endothelial responses. Subjects with the greatest decline in FMD over 10 years had a significant increase in mean arterial pressure but similar cardiovascular phenotype.

CONCLUSION

Persistently reduced, or declining, endothelial function during adolescence, in the absence of overt cardiovascular disease, is a sensitive early marker associated with subclinical changes in blood pressure (BP) and an adverse cardiovascular phenotype. The findings highlight the potential importance of endothelial responses during adolescence in primary prevention strategies for hypertension.

Association of left ventricular hypertrophy with incident hypertension: the multi-ethnic study of atherosclerosis

Increased left ventricular (LV) mass and changes in LV geometry may precede hypertension onset. The authors examined the associations of LV mass and geometry, assessed by cardiac magnetic resonance imaging, with hypertension incidence in 2,567 normotensive participants enrolled in 2000-2002 in the Multi-Ethnic Study of Atherosclerosis, an ethnically diverse, population-based, US study. Over a median follow-up of 4.8 years, 745 (29%) participants developed hypertension. In a fully adjusted model including baseline blood pressure, the relative risks of incident hypertension from the lowest to highest LV mass quartile were 1.00 (referent), 1.13 (95% confidence interval (CI): 0.89, 1.43), 1.28 (95% CI: 1.00, 1.63), and 1.78 (95% CI: 1.38, 2.30) (P < 0.001 for linear trend). Higher levels of LV concentric geometry, defined by higher LV mass to end-diastolic volume quartiles, were associated with higher risk of incident hypertension in a fully adjusted model (P = 0.044 for linear trend). In a final model containing both quartiles of LV mass and LV mass/volume along with all covariates including baseline blood pressure, higher LV mass quartiles were associated with incident hypertension (P < 0.001 for linear trend), whereas higher LV mass/volume quartiles were not (P = 0.643 for linear trend). In this multiethnic cohort, alterations in LV mass preceded hypertension onset among normotensive individuals.

Hemodynamic variables during exercise in childhood and resting systolic blood pressure levels 6 years later in adolescence: the European Youth Heart Study

The aim of this study was to analyze whether systolic blood pressure (SBP), heart rate (HR) and rate pressure product (RPP) during exercise in childhood can predict resting SBP levels in adolescence independent of resting SBP and conventional cardiovascular risk factors. We studied this in a sample of Danish children followed longitudinally for 6 years. The study comprised 226 children randomly sampled at age 9, who had their blood pressure and HR measured during ergometer exercise to exhaustion and was reassessed in adolescence. SBP and RPP during exercise in stage two of the test were positively associated with future resting SBP, independent of resting SBP in childhood (P=0.045 and P=0.013, respectively). After additional adjustment for conventional cardiovascular risk factors the associations with SBP and RPP during stage two on future resting SBP only slightly materially change, although only RPP remained significant (P=0.059 and P=0.012, respectively). No significant independent associations were observed for HR during exercise, but associations were in the same direction. Our results supports that measuring SBP and RPP, during a standard acute ergometer exercise test in children, improves the prediction of future SBP levels during rest in adolescence independent of resting SBP and conventional cardiovascular risk factors.

Antihypertensive effect of Cu and Mg enriched modified poultry eggPsi on Zn-induced hypertension in Wistar rat

PROJECT

Excessive bioavailability of Zn either due to genetic predisposition or its high concentration in diet has been linked to increase in the prevalence of hypertension (HT) implicating the resultant deficiencies of Cu and Mg as its cause in some populations. To combat their nutritional deficiencies, a modified poultry egg (ME(Psi)) was designed containing higher amounts of Cu, Mg and other antioxidants (vitamin E and linolenic acid) in their optimized concentrations. Prior to its human clinical trials, its efficacy was tested in Zn induced HT Wistar rat model in the present study.

PROCEDURE

In one set, the rats were fed on equicaloric semi-synthetic basal diet containing 20 mg Zn/kg diet (control diet-I, control group-I), Zn-induced-hypertensive-diets-II and III (Zn-HT-diet-II and Zn-HT-diet-III) containing 40 and 80 mg Zn/kg diet (groups-II and III) for 180 days. In another set, the rats were initially fed Zn-HT-diet-II and Zn-HT-diet-III for 90 days and then shifted to ME(Psi) mixed Zn-HT-diet-II and III designated as groups-IIME and IIIME fed for another 90 days completing 180 days of feeding.

RESULTS

The results revealed that increase in systolic pressure (SP) and heart rates (HR) were Zn concentration dependent and coincided well with higher serum Zn, Cu, Mg, aldosterone, cortisol, dyslipidemia and higher Zn, and low Cu and Mg concentrations in liver of groups-II and III rats. On feeding ME(Psi) mixed diets, a significant reduction in SP and HR were linked with decrease in serum Zn, Cu, Mg, aldosterone, cortisol and blood lipid profile along with fall in Zn and rise in Cu and Mg concentrations in liver of groups-IIME and IIIME approaching closer to control group-I.

CONCLUSION

This study makes the basis for human clinical trials of ME(Psi) on HT patients who exhibit high Zn, Cu and Mg in their blood serum.

Association between exaggerated blood pressure response to exercise and serum asymmetric dimethylarginine levels

BACKGROUND

The exaggerated blood pressure response to exercise (EBPR) is an independent predictor of hypertension. Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide inhibitor and higher plasma levels of ADMA are related to increased cardiovascular risk. The aim of this study is to identify the relationship between ADMA and EBPR.

METHODS AND RESULTS

A total of 66 patients (36 with EBPR and 30 as controls) were enrolled in the study. EBPR is defined as blood pressure (BP) measurements > or =200/100 mmHg during the treadmill test. All the subjects underwent 24-h ambulatory BP monitoring. L-arginine and ADMA levels were measured using a high performance lipid chromatography technique. The serum ADMA levels were increased in the EBPR group compared to the healthy controls (4.0+/-1.4 vs 2.6+/-1.1 micromol/L respectively, P=0.001), but L-arginine levels were similar in the 2 groups (P=0.19). The serum ADMA levels were detected as an independent predictor of EBPR (odds ratio 2.28; 95% confidence interval 1.22-4.24; P=0.002).

CONCLUSIONS

Serum ADMA levels might play a role in EBPR to exercise.

Increased left ventricular mass and diastolic dysfunction are associated with endothelial dysfunction in normotensive offspring of subjects with essential hypertension

OBJECTIVES

We aimed to investigate left ventricular (LV) morphology and function in normotensive offspring of subjects with essential hypertension (familial trait - FT), and to determine the association between LV mass and determinants of LV diastolic function and endothelium-dependent (NO-mediated) dilation of the brachial artery (BA).

MATERIALS AND METHODS

The study encompassed 76 volunteers of whom 44 were normotonics with FT aged 28-39 (mean 33) years and 32 age-matched controls without FT. LV mass and LV diastolic function was measured using conventional echocardiography and tissue Doppler imaging (TDI). LV diastolic filling properties were assessed and reported as the peak E/A wave ratio, and peak septal annular velocities (E(m) and E(m)/A(m) ratio) on TDI. Using high-resolution ultrasound, BA diameters at rest and during reactive hyperaemia (flow-mediated dilation--FMD) were measured.

RESULTS

In subjects with FT, the LV mass index was higher than in controls (92.14+/-24.02 vs 70.08+/-20.58); p<0.001). Offspring of hypertensive families had worse LV diastolic function than control subjects (lower E/A ratio, lower E(m) and E(m)/A(m) ratio; p<0.001). In subjects with FT, FMD was decreased compared with the controls (6.11+/-3.28% vs 10.20+/-2.07%; p<0.001). LV mass index and E(m)/A(m) ratio were associated with FMD (p<0.001).

CONCLUSIONS

In normotensive individuals with FT, LV morphological and functional changes were found. We demonstrated that an increase in LV mass and alterations in LV diastolic function are related to endothelial dysfunction.

Cardiac structures track during the first 2 years of life and are associated with fetal growth and hemodynamics: the Generation R Study

BACKGROUND

The aim of this study is to examine whether cardiac size and function track in early childhood and are associated with fetal and early postnatal growth and blood flow characteristics.

METHODS

This study was embedded in a population-based prospective cohort study from fetal life onward. Fetal growth and fetal and placental blood flow parameters in second and third trimester of pregnancy were measured by ultrasound and Doppler. Left cardiac structures and shortening fraction were measured postnatally at the ages of 1.5, 6, and 24 months. Analyses were based on 1,001 children.

RESULTS

Left ventricular mass tended to remain in the lowest and highest quartiles from the age of 1.5 to 24 months (odds ratio 1.70, 95% confidence interval [CI] 1.10-2.63) and 2.15 (95% CI 1.41-3.30), respectively. Similar results were found for aortic root diameter and left atrial diameter. Birth weight was positively associated with aortic root diameter (0.08 mm, 95% CI 0.01-0.17; per SD increase) and left ventricular mass (0.65 g, 95% CI 0.09-1.21; per SD increase). Resistance indices of the umbilical and uterine arteries showed weak tendencies toward inverse associations with left cardiac structures. Fetal cardiac output was positively associated with both left atrial diameter (increase of 1.96 mm, 95% CI 1.28-2.64; per mL/min increase) and left ventricular mass (increase of 1.79 g, 95% CI 0.35-3.22; per mL/min increase).

CONCLUSIONS

This study suggest moderate tracking of left cardiac structures during the first 2 years and that small size and hemodynamic variations in fetal life have consequences for postnatal cardiac size and function.

Left ventricular mass and incident hypertension in individuals with initial optimal blood pressure: the Strong Heart Study

OBJECTIVE

Metabolic abnormalities have been shown to predict 8-year incident arterial hypertension in individuals with optimal blood pressure. As echocardiographic left ventricular mass has also been reported to predict incident hypertension in individuals with baseline blood pressure of less than 140/90 mmHg, we determined whether left ventricular mass predicts 4-year incident hypertension also in individuals with initial optimal blood pressure (<120/80 mmHg), independent of metabolic factors influencing blood pressure.

METHODS

We studied 777 of 3257 members of the American Indian population-based Strong Heart Study cohort with optimal blood pressure (34% men, 45% obese, and 35% diabetic), aged 57 +/- 7 years, and without prevalent cardiovascular disease.

RESULTS

Over 4 years, 159 individuals (20%, group H) developed hypertension (blood pressure >/=140/90 mmHg). They had a greater baseline BMI, waist girth, and blood pressure (112/69 vs. 109/68 mmHg, all P < 0.03) than those remaining normotensive (group N), with similar lipid profile and renal function. At baseline, left ventricular mass was significantly greater in group H than in group N (P < 0.004). The difference in left ventricular mass was confirmed after controlling for initial BMI, systolic blood pressure, homeostatic model assessment index, and diabetes. The probability of incident hypertension increased by 36% for each standard deviation of left ventricular mass index (P = 0.006), independent of covariates. Participants with left ventricular mass of more than 159 g (75th percentile of distribution) had 2.5-fold (95% confidence interval, 1.4-3.6; P < 0.001) higher adjusted risk of incident hypertension than those below this value.

CONCLUSION

Left ventricular mass predicts incident arterial hypertension in individuals with initially optimal blood pressure. This association is independent of body build, prevalent diabetes, and initial blood pressure.

Change of genetic determinants of left ventricular structure in adolescence: longitudinal evidence from the Georgia cardiovascular twin study

BACKGROUND

Genetic contribution to left ventricular (LV) structure is generally recognized, but whether and how this influence varies by ethnicity or with age is unknown.

METHODS

Participants were 517 European-American (EA) and African-American (AA) twin pairs (mean age: 14.6 +/- 3.0) at visit 1 and 422 EA and AA twin pairs at follow-up 4.1 years later. Echocardiograms were obtained on both visits. Data were analyzed using the structural equation modeling software Mx.

RESULTS

Body mass index (BMI) was a strong predictor for all LV measures at both visits 1 and 2, accounting for 3.5-24.2% of the total variance. Hemodynamics explained up to 4.5% additional LV measures variance. After adjusting for BMI, LV measures showed substantial heritability (range: 21-71%). Best-fitting longitudinal models revealed considerable novel genetic effects on the interventricular septum, posterior wall-, and relative wall thickness (RWT) (but not LV internal diameter), accounting for 32-41% of the phenotypic variance at visit 2, with no significant gender and ethnic effects. There was a gender difference for LV mass index in AAs (P < 0.01), with a significant influence of novel genetic effects in males (47%), but not in females. No gender difference was seen in EAs, with 34% of the phenotypic variance at visit 2 attributable to novel genetic effects.

CONCLUSIONS

The heritability of cardiac structure and geometry was equally substantial in both AAs and EAs. Significant novel genetic influences were detected for all measures but LV inner diameter and LV mass index in AA females. Further developmental genetic studies are warranted to elucidate the nature of the emerging gene effects during the transition from adolescence to adulthood.

Increased blood pressure levels relative to subjective feelings of intensity of exercise determined with the Borg scale in male patients with hypertension

We examined the hemodynamic responses to exercise and symptoms in 37 male patients with untreated essential hypertension, and compared the findings with those in 32 age-matched healthy male volunteers by performing a graded symptom-limited exercise test using a bicycle ergometer. The subjective feeling of intensity of exercise was determined using the Borg scale. In the relationship between Borg scores and blood pressure (BP), patients with hypertension showed higher systolic BP and diastolic BP relative to the Borg scores than the controls. Consequently, patients with hypertension showed significantly higher systolic BP with Borg scores < or = 3 (subjective symptoms < or = moderately hard) than the controls (177.8 +/- 27.0 vs. 143.7 +/- 17.9 mmHg, p < 0.0001). Similarly, significantly higher diastolic BP with Borg scores < or = 3 was observed in patients with hypertension than in the controls (101.6 +/- 12.0 vs. 82.6 +/- 11.6 mmHg, p < 0.0001). The pulse pressure with Borg scores < or = 3 was also significantly higher in patients with hypertension than in the controls (76.2 +/- 20.6 vs. 61.0 +/- 13.6 mmHg, p < 0.0001). Hypertensive patients showed a decrease in the high-frequency power of heart rate variability at initial low-load exercise. In conclusion, the present study revealed that there was a greater BP response relative to the Borg score in patients with hypertension than in the controls. Autonomic nerve activity may contribute to some extent to these different relations. A determination of the relationship between the subjective feeling of intensity of the exercise and BP levels caused by a given intensity of load is essential before exercise training in patients, at least in males, with hypertension to avoid increasing the risk of cardiovascular events in association with excessive exercise training.

Ankle blood pressure as a predictor of total and cardiovascular mortality

BACKGROUND

The ankle blood pressure is commonly used as a ratio to the brachial blood pressure, called ankle-brachial index (ABI). Very few studies have considered the independent value of the ankle blood pressure without indexing it to the brachial blood pressure. We examined the value of ankle blood pressure, together with the exercise blood pressure, as a predictor of cardiovascular (CVD) and total mortality.

METHODS

A prospective follow-up study of 3,858 consecutive ambulatory patients (mean age 51 years, 65,9% male) referred to a symptom-limited exercise test between August 1989 and December 1995. The cohort was followed up for all-cause and CVD mortality until December 31, 2004, by record linkage with the National Causes-of-Death Register. The independent value of ankle blood pressure as a predictor of cardiovascular and total mortality was assessed using Cox proportional hazards modelling.

RESULTS

The average follow-up time was 14 years, during which 346 persons died, 108 of them due to CVD. Persons with normal (<140 mmHg) resting brachial blood pressure, ankle blood pressure < 175 mmHg and exercise blood pressure at moderate exercise level < or =215 mmHg at baseline investigation, had the best prognosis and were taken as the reference category. Among persons with elevated ankle blood pressure (> or =175 mmHg) but normal or borderline resting brachial pressure and normal exercise blood pressure (< or =215 mmHg) at moderate exercise level the multivariate-adjusted hazard ratios (HR, 95% confidence interval) for CVD and total mortality were 2.70 (1.52 - 4.80) and 2.13 (1.58 - 2.85), respectively. Similar and equally significant HRs were observed in persons with both elevated ankle blood pressure and elevated exercise blood pressure, as well as in those persons with elevated exercise blood pressure but ankle blood pressure < 175 mmHg.

CONCLUSION

These results suggest that the ankle blood pressure has an independent value as a marker of arterial stiffness or subclinical atherosclerosis and a risk of future mortality in middle-aged, asymptomatic persons.

Selected zinc metabolism parameters and left ventricle mass in echocardiographic examination in primary arterial hypertension

The basal systolic and diastolic blood pressure, body mass index, left ventricular mass, serum and lymphocyte zinc levels, serum aldosterone, plasma rennin and angiotensin-converting enzyme activities, sodium and potassium levels, and the total and ouabain-dependent rate constants of zinc efflux from lymphocytes were measured in a group of 41 individuals of both sexes (overall age 46.3 +/- 11.4 years), of which 18 were women (48.5 +/- 7.1 years old) and 23 were men (44.7 +/- 13.8 years old). There were no significant differences between these parameters while dividing the subjects into groups according to sex, despite differences in weight, left ventricle mass, plasma rennin activity, and serum aldosterone content. Only the total and ouabain-dependent rate constants of zinc efflux from lymphocytes slightly negatively correlated to left ventricular mass, r = -0.30 to r = -0.36. This may constitute indirect evidence of zinc deficiency in cardiomyocytes of some hypertensive individuals with left ventricular hypertrophy.

White coat hypertension in childhood: evidence for end-organ effect

OBJECTIVE

To evaluate the hypothesis that white coat hypertension (WCH) represents a prehypertensive state by correlating ambulatory blood pressure monitoring (ABPM) results with BP response to treadmill exercise (TE) and echocardiographic measurement of left ventricular mass index (LVMI) in children with high blood pressure (HBP).

STUDY DESIGN

We evaluated 119 consecutive children age 6 to 18 years (mean = 13.3 years; 65% male) referred for HBP. Office systolic BP (SBP) exceeded the 95th percentile for age/sex/height in all of the children; 10% also had elevated diastolic BP (DBP). WCH was defined as elevated office SBP +/- elevated DBP with normal mean awake ABPM-SBP. ABPM classified 62 subjects as having WCH and 57 as having HBP.

RESULTS

Office BP did not differ between the 2 groups. As defined, awake ABPM-SBP was lower in the WCH group (males: HBP, 142 +/- 12 vs WCH, 124 +/- 5; females: HBP, 137 +/- 8 vs WCH, 121 +/- 5). Awake and asleep DBP and asleep SBP were significantly lower in the WCH group. On TE, maximal SBP exceeded norms for age/sex/body surface area in 63% of the HBP group and 38% of the WCH group. LVMI exceeded the 95th percentile for age/sex in 59% of the males and 90% of the females in the HBP group and in 33% of the males and 36% of the females in the WCH group.

CONCLUSIONS

Exaggerated exercise BP and/or increased LVMI in 62% of those subjects with WCH suggest that this diagnosis in children may represent a prehypertensive state.

Role of zinc in regulation of arterial blood pressure and in the etiopathogenesis of arterial hypertension

Increased gastrointestinal absorption and urinary excretion of zinc has been confirmed in experimental and clinical studies on primary arterial hypertension as a result from changes of intracellular and extracellular zinc content. In arterial hypertension, the levels of zinc in serum, lymphocyte, and bone decrease while increasing in heart, erythrocytes, kidney, liver, suprarenal glands and spleen. These changes result in the loss of zinc homeostasis that leads to various degrees of deficiency, not entirely compensated by nutritional factors or increased absorption in the gastrointestinal tract. Loss of zinc homeostasis can be both cause and effect of high blood pressure. In the present review, the role of zinc metabolism changes and its mechanisms in arterial hypertension are discussed.

Exaggerated blood pressure response to exercise is associated with carotid atherosclerosis in apparently healthy men

OBJECTIVE

Although an exaggerated systolic blood pressure (SBP) response to exercise is a predictor of future hypertension and cardiovascular mortality, the underlying mechanisms are not fully understood. We tested the hypothesis that an exaggerated SBP response is associated with carotid atherosclerosis in a cross-sectional study of 9073 healthy men (aged 47.8 +/- 8.8 years).

METHODS

Exaggerated SBP response was defined as an SBP of 210 mmHg or greater during a maximal treadmill test. Carotid atherosclerosis was defined as stenosis greater than 25% or intima-media thickness greater than 1.2 mm using B-mode ultrasonography.

RESULTS

An exaggerated SBP response was present in 375 men (4.1%). The proportion of individuals with carotid atherosclerosis in the group with an exaggerated SBP response to exercise was higher than in the group with a normal SBP response (14.4 versus 5.3%, P < 0.001). In a multivariable logistic regression model, individuals with an exaggerated SBP (>or= 210 mmHg) response to exercise had a 2.02 times [95% confidence interval (CI) 1.33-3.05] increased risk of carotid atherosclerosis compared with individuals with an SBP response of less than 210 mmHg. The highest quartile (> 61 mmHg) group of relative exercise-induced increases in SBP showed a 1.57 (95% CI 1.18-2.08) greater risk of carotid atherosclerosis compared with individuals in the lowest quartile (< 38 mmHg) in the adjusted model.

CONCLUSIONS

These results suggest that an exaggerated SBP response to exercise is strongly associated with carotid atherosclerosis, independent of established risk factors in healthy men. It may be an important factor in evaluating hypertension related to target-organ damage.

Cardiovascular reactivity in cardiovascular disease: "once more unto the breach"

Discussed here are conceptual and methodologic issues that bear on the role of behaviorally evoked cardiovascular reactivity in cardiovascular disease. It is argued that recent criticisms concerning the validity of cardiovascular reactivity as a stable dimension of individual differences arise from inadequacies of measurement prevalent in prior literature. With standardization of test stimuli and application of psychometric principles lo protocol development, assessment of reactivity are found to be highly reliable and, in turn, to demonstrate the dispositional nature of this construct. Recent studies also document an underlying heterogeneity of hemodynamic reactions to stress, with distinct cardiac and vascular components. Because hemodynamic adjustments show some plasticity under differing task conditions, responses seen in particular contexts reflect influences of both an individual-specific response potential and response-eliciting properties of the stimulus. On the question of disease relevance, it is concluded that cardiovascular reactivity cannot yet be considered an established risk factor for either coronary heart disease or hypertension. However, the preponderance of existing clinical, experimental. and epidemiologic evidence is consistent with such an association and warrants further study in the context or population-based, prospective investigation.

Cardiac remodeling in systemic hypertension

Experimental and clinical studies provide evidence that hypertension is causally related to adverse cardiac structural changes, such as LA enlargement, LV hypertrophy and myocardial fibrosis, and functional changes inclusive of LV systolic and diastolic dysfunction. These changes are induced by both hemodynamic and nonhemodynamic factors. There is accumulating evidence from several small and large clinical trials that various classes of antihypertensive therapy prevent and regress LVH and myocardial fibrosis. Prevention and reversal of LVH are associated with an improvement in cardiac function and with a decline in risk of adverse cardiovascular outcomes. Prevention of LVH should be a priority in subjects with hypertension. In patients with hypertensive heart disease, the components of therapy must comprise optimization of BP and regression of LVH. Future targets of therapy in hypertensive heart disease may include regression of myocardial fibrosis, normalization of LA size, and improvement in LV diastolic function.

Growth of left ventricular mass in African American and European American youth

Increased left ventricular mass has been established as a strong risk factor for cardiovascular morbidity and mortality. To evaluate growth of left ventricular mass from childhood into early adulthood and its possible sociodemographic, anthropometric, and hemodynamic moderators, individual growth curves across age of left ventricular mass were created for 687 African American and European American males and females with a maximum of 10 annual assessments (age, 8.2 to 27.5 years). African Americans and males had significantly greater left ventricular mass (P<0.001) than did European Americans and females, respectively. Males also showed a larger rate of change in left ventricle mass than did girls (P<0.001). The ethnicity and gender effects on left ventricular mass only became apparent in early adolescence, and they persisted when controlling for socioeconomic status and anthropometric and hemodynamic variables. Body mass index and height were the strongest anthropometric predictors, and pulse pressure was the strongest hemodynamic predictor of left ventricular mass. Although significant, the contribution of pulse pressure to the prediction of left ventricular mass was small, once body mass index and height were entered into the model. The results of the present study suggest that increased left ventricular mass in boys and African Americans has its origin in late childhood. Apart from these ethnicity and gender effects, individual differences in cardiac growth can mainly be explained by body growth and increases in general adiposity.

Cardiovascular recovery from stress predicts longitudinal changes in blood pressure

Cardiovascular reactivity and recovery were examined as predictors of blood pressure changes over 3 years. Blood pressure and heart rate readings were obtained from 73 men and women aged 18-20 years during cold pressor, mental arithmetic, tourniquet ischemia, cycle exercise and step exercise tasks. Regression analyses indicated that after adjustment for initial blood pressure, initial age, initial body-mass index, sex, parental history of hypertension, and length of follow-up, heightened heart rate reactivity to mental arithmetic was associated with increased follow-up systolic blood pressure (DeltaR(2)=0.04, P<0.05). Systolic blood pressure recovery from cold pressor and tourniquet ischemia were also positively related to follow-up systolic blood pressure (DeltaR(2)=0.04 and 0.04, respectively, P<0.05) and remained so even after adjustment for the corresponding cardiovascular reactivity measures. These findings suggest that cardiovascular reactivity and recovery measures are modest predictors of longitudinal changes in blood pressure.

Cardiovascular responsivity to stress in adolescents with and without persistently elevated blood pressure

OBJECTIVES

The goal of this study was to compare the cardiovascular responses to behavioural stressors of three groups of adolescents who differed in blood pressure status across assessments.

DESIGN

Casual blood pressure of adolescents who were identified as having elevated blood pressure during a school screen was re-evaluated in the laboratory. The adolescents were classified into two groups: (i) those with consistently elevated blood pressure across school and laboratory assessments and (i) those with labile blood pressure whose blood pressure in the laboratory was below 130/80 mmHg. A comparison group of adolescents with consistently normal blood pressure was also included.

METHODS

Cardiovascular parameters were assessed during rest and during two behavioural stressors, the evaluated speaking task and the mirror tracing task.

RESULTS

Adolescents with elevated blood pressure were more vascularly responsive across stressors than adolescents with labile blood pressure, who, in turn, were more reactive than adolescents with normal blood pressure.

CONCLUSIONS

These results suggest that vascular reactivity to behavioural stressors may be useful in predicting risk of hypertension because of its sensitivity in distinguishing adolescents with consistently elevated blood pressure from those with labile blood pressure and those with normal blood pressure.

Association between muscle fiber composition and blood pressure levels during exercise in men

Normotensive individuals with a magnified blood pressure (BP) level during exercise have an increased risk for developing hypertension. The purpose of this study was to determine if skeletal muscle fiber type is related to the BP level during exercise. Peak BP was determined in 35 normotensive, middle-aged (mean +/- SE, 46.0 +/- 1.8 years) men during maximal treadmill exercise. Fiber distribution (I, IIa, IIb) was measured in muscle samples (percutaneous needle biopsy) from the vastus lateralis and lateral gastrocnemius. The systolic BP during exercise was significantly (P < .05) related to the percentage of type IIb fibers in both the vastus lateralis (r = 0.37) and gastrocnemius (r = 0.38). Mean arterial pressure BP was also related to the percentage of type IIb fibers in the gastrocnemius (r = 0.39, P < .05), with a similar trend evident in the vastus lateralis (r = 0.31, P = 0.08). The percentage of type IIb muscle fibers in both muscle groups was associated with (P < .05) body fat (vastus lateralis, r = 0.44; gastrocnemius, r = 0.43). There were no relationships between the relative percentage of type I or IIa fibers with any BP parameters. Maximal oxygen consumption was negatively related to BP, but only when expressed relative to body weight (mL x kg(-1) x min(-1)). These data suggest that muscle morphology is related to the blood pressure level during exercise and provides insight into factors that may predispose individuals toward the development of hypertension and cardiovascular disease.

Predicting heart growth during puberty: The Muscatine Study

OBJECTIVES

During childhood, heart growth is closely associated with somatic growth including increases in body weight, fat-free body mass (FFM), and height. However, with age, greater variability in heart size in relationship to body size is observed, presumably attributable to the increased effect of cardiac workload. At this time, little is known as to what functional attributes (eg, aerobic fitness) contribute to cardiac workload and the relative contribution of these attributes to heart growth during childhood and adolescence. In this article, we report cross-sectional and longitudinal relationships among aerobic fitness, body size, blood pressure (BP), and left ventricular mass (LVM) through puberty including the predictors of heart growth during puberty and the tracking of LVM from pre-puberty to late and post-puberty. Describing the predictors of heart size and heart growth and establishing the likelihood that a large heart, relative to peers, may (or may not) remain a large heart should aid pediatricians in discerning between normal developmental increases in LVM and increases in LVM suggestive of excessive heart growth (left ventricular hypertrophy).

METHODOLOGY

Using a repeated-measures design, we assessed aerobic fitness, FFM, fatness, weight, height, sexual maturation, resting BP, peak exercise BP, and LVM in 125 healthy children (mean baseline age: 10.5 years) for a period of 5 years. All subjects were either in prepuberty or early puberty at the beginning of the study. At follow-up, 110 subjects attempted all research procedures (87% of the initial cohort). Using anthropometry and bioelectrical impedance, we measured FFM, fatness, weight, and height quarterly (once every 3 months) for a total of 20 examinations. Resting BP and LVM (2-dimensional echocardiography) were also assessed quarterly. Aerobic fitness, peak exercise BP, and sexual maturation (staging of secondary sex characteristics and, for boys, serum testosterone) were measured annually (5 examinations). The same field staff conducted all examinations. Statistical methods included Spearman rank correlation coefficients (r(s)) calculated to estimate how well the year 5 LVM was predicted by LVM at earlier years. We also categorized the LVM data into tertiles and reported the percentage who remained in the extreme tertiles in year 5, given they began in that tertile in year 1. Gender-specific stepwise multivariate analysis was used to evaluate predictors of follow-up LVM and predictors of changes in LVM. The latter model examined whether the variability in the changes in LVM, as quantified by subject-specific slopes, could be explained by changes in predictor variables, also quantified by subject-specific slopes.

RESULTS

At baseline and at follow-up, boys tended to be taller, leaner, more aerobically fit, and had greater LVM than girls. Rate of change for these variables was also greater in boys than girls. For example, LVM increased 62% in boys and 48% in girls. At year 5, subjects had advanced at least 1 stage in genital or breast development and over 80% of the subjects were in late- or post-puberty. Significant and strong tracking of heart size (r(s) =.65-.87) was observed. The likelihood that a subject would be in an extreme tertile for heart size at follow-up was approximately doubled if he or she started there at baseline. In boys, baseline FFM explained 54% of the variability in follow-up LVM. Change in aerobic fitness and change in FFM explained 55% of the variability in change in LVM. In girls, baseline aerobic fitness and fatness explained 45% of the variability in follow-up LVM. Because FFM did not enter in this model, we constructed an alternative model in which baseline aerobic fitness adjusted for FFM was entered. Using this approach, 43% of the variability in follow-up LVM was explained by baseline FFM, fatness, and adjusted aerobic fitness. Change in FFM explained 58% of the variability in change in LVM. (ABSTRACT TRUNCATED)

Relationship between left ventricular mass and hemodynamic responses to physical and mental stress

OBJECTIVE

Increased left ventricular mass (LVM) is predictive of future cardiac morbidity and mortality. Although casual and ambulatory blood pressure (BP) predict LVM, other hemodynamic determinants of LVM are incompletely understood. The present study examines laboratory-induced hemodynamic responses (to exercise, cold, and mental stress) and 24-hour ambulatory measures as predictors of LVM.

METHODS

Thirty-six healthy non-hypertensive subjects (mean age 33.9 +/- 9.4 years; 23 women, 13 men) were tested with mental stress, cold pressor, and treadmill exercise in the laboratory and 24-hour ambulatory BP monitoring. LVM was measured using two-dimensional targeted M-mode echocardiography and indexed for body surface area (LVMI).

RESULTS

All laboratory tasks produced significant hemodynamic responses (p's < 0.01). Systolic blood pressure responses to mental stress (r = 0.42, p < 0.01) and cold pressor (r = 0.34, p < 0.05) were significantly related to LVM. After adjusting for body size, the mental stress-induced SBP responses was the only significant predictor of LVMI (r = 0.32, p < 0.05). Exercise SBP responses were associated to LVMI in men (r = 0.63, p = 0.02), but not in women (r = 0.02, p = n.s.). Multivariate regression analyses revealed that SBP during mental stress was significantly predictive of LVMI (beta = 0.65, p = 0.05), independent of baseline SBP, 24-hour ambulatory SBP, and other control variables.

CONCLUSION

The present results indicate that SBP responses to mental stress are significantly related to LVM among healthy individuals, independently of baseline SBP, 24-hour ambulatory BP, age, body size, and sex. Blood pressure responses to exercise show a robust association with LVM in men but not in women. Hemodynamic responses elicited during laboratory tasks may therefore reveal important information about the pathophysiological processes involved in the development of cardiac end-organ damage.

Hemodynamic function at rest, during acute stress, and in the field: predictors of cardiac structure and function 2 years later in youth

Left ventricular hypertrophy is an independent predictor of cardiovascular morbidity and mortality. However, predictors of cardiac structure and function in youth are not completely understood. On 2 occasions (2.3 years apart), we examined 146 youth aged initially 10 to 19 years (mean age, 14.2+/-1.8 years). On the initial visit, hemodynamic function was assessed at rest, during laboratory stress (ie, orthostasis, car-driving simulation, video game, and forehead cold), and in the field (ie, ambulatory blood pressure). Quantitative M-mode echocardiograms were obtained on both visits. On both visits, black compared with white youth had higher resting laboratory systolic blood pressure (P<0.02), greater relative wall thickness (P<0.003), greater left ventricular mass indexed by either body surface area or height(2.7) (P<0.01 for both), and lower midwall fractional shortening ratio (P<0.05). Hierarchical stepwise regression analysis indicated that significant independent predictors of follow-up left ventricular mass/height(2. 7) were the initial evaluation of left ventricular mass/height(2.7), body mass index, gender (males more than females), and supine resting total peripheral resistance (final model R(2)=0.53). Left ventricular mass/body surface area was predicted by initial left ventricular mass/body surface area, weight, gender, mean supine resting total peripheral resistance, and systolic pressure response to car-driving simulation (final model R(2)=0.48). Midwall fractional shortening was predicted by initial midwall fractional shortening, race (white more than black), and lower mean supine total peripheral resistance (final model R(2)=0.13). The clinical significance of these findings and their implications for improved prevention of cardiovascular diseases are yet to be determined.

Modes of cardiovascular regulation during middle childhood

Obtaining meaningful baseline measures of children's cardiovascular activity (CVA) has been difficult because of constraints inherent to laboratory procedures that are used to assess individual differences in response to stress. To circumvent these problems, we performed repeated baseline measures of pulse rate (PR) and blood pressure for 174 children (aged 7-10 yr) in their natural school setting throughout 2 1-week periods. In addition, experimental assessments of cardiovascular reactivity (CVR) were conducted after each baseline period while children participated in a challenging cognitive task. Multivariate analyses of physiological indices revealed three primary styles of cardiovascular functioning. Two of them, characterizing children either with high PR and low blood pressure or conversely with low PR and high blood pressure, have already been described in the research literature. However, analyses also revealed a third group of children (48% of the subjects) who had both low PR and low blood pressure. Findings indicate developmental differences in cardiovascular regulation and highlight the need to consider both variations in baseline CVA as well as in CVR when examining children's physiological adaptation in everyday settings.