Neurogenic pressor episodes fail to cause hypertension, but do induce cardiac hypertrophy

The Promise and Illusion of Continuous, Cuffless Blood Pressure Monitoring

PURPOSE OF REVIEW

Blood pressure (BP) fluctuations outside of clinic are increasingly recognized for their role in the development of cardiovascular disease, syncope, and premature death and as a promising target for tailored hypertension treatment. However, current cuff-based BP devices, including home and ambulatory devices, are unable to capture the breadth of BP variability across human activities, experiences, and contexts.

RECENT FINDINGS

Cuffless, wearable BP devices offer the promise of beat-to-beat, continuous, noninvasive measurement of BP during both awake and sleep periods with minimal patient inconvenience. Importantly, cuffless BP devices can characterize BP variability, allowing for the identification of patient-specific triggers of BP surges in the home environment. Unfortunately, the pace of evidence, regulation, and validation testing has lagged behind the pace of innovation and direct consumer marketing. We provide an overview of the available technologies and devices for cuffless BP monitoring, considerations for the calibration and validation of these devices, and the promise and pitfalls of the cuffless BP paradigm.

Healthy cardiac myocytes can decrease sympathetic hyperexcitability in the early stages of hypertension

Sympathetic neurons are powerful drivers of cardiac excitability. In the early stages of hypertension, sympathetic hyperactivity is underpinned by down regulation of M current and increased activity of Cav_2.2 that is associated with greater intracellular calcium transients and enhanced neurotransmission. Emerging evidence suggests that retrograde signaling from the myocyte itself can modulate synaptic plasticity. Here we tested the hypothesis that cross culturing healthy myocytes onto diseased stellate neurons could influence sympathetic excitability. We employed neuronal mono-cultures, co-cultures of neonatal ventricular myocytes and sympathetic stellate neurons, and mono-cultures of sympathetic neurons with media conditioned by myocytes from normal (Wistar) and pre-hypertensive (SHR) rats, which have heightened sympathetic responsiveness. Neuronal firing properties were measured by current-clamp as a proxy for neuronal excitability. SHR neurons had a maximum higher firing rate, and reduced rheobase compared to Wistar neurons. There was no difference in firing rate or other biophysical properties in Wistar neurons when they were co-cultured with healthy myocytes. However, the firing rate decreased, phenocopying the Wistar response when either healthy myocytes or media in which healthy myocytes were grown was cross-cultured with SHR neurons. This supports the idea of a paracrine signaling pathway from the healthy myocyte to the diseased neuron, which can act as a modulator of sympathetic excitability.

Association of acculturation with cardiac structure and function among Hispanics/Latinos: a cross-sectional analysis of the echocardiographic study of Latinos

OBJECTIVE

Hispanics/Latinos, the largest immigrant population in the USA, undergo the process of acculturation and have a large burden of heart failure risk. Few studies have examined the association of acculturation on cardiac structure and function.

DESIGN

Cross-sectional.

SETTING

The Echocardiographic Study of Latinos.

PARTICIPANTS

1818 Hispanic adult participants with baseline echocardiographic assessment and acculturation measured by the Short Acculturation Scale, nativity, age at immigration, length of US residence, generational status and language.

PRIMARY AND SECONDARY OUTCOME MEASURES

Echocardiographic assessment of left atrial volume index (LAVI), left ventricular mass index (LVMI), early diastolic transmitral inflow and mitral annular velocities.

RESULTS

The study population was predominantly Spanish-speaking and foreign-born with mean residence in the US of 22.7 years, mean age of 56.4 years; 50% had hypertension, 28% had diabetes and 44% had a body mass index >30 kg/m². Multivariable analyses demonstrated higher LAVI with increasing years of US residence. Foreign-born and first-generation participants had higher E/e' but lower LAVI and e' velocities compared with the second generation. Higher acculturation and income >$20K were associated with higher LVMI, LAVI and E/e' but lower e' velocities. Preferential Spanish-speakers with an income <$20K had a higher E/e'.

CONCLUSIONS

Acculturation was associated with abnormal cardiac structure and function, with some effect modification by socioeconomic status.

Effect of self-initiated and fully-automated self-measurement on blood pressure

Self-measurement of blood pressure (BP) is regularly used to diagnose hypertension and to monitor BP at home. We recently showed that self-measurement of BP may elicit a pressor or 'auto-cuff' response. In this study we examined whether the pressor response is different between self-initiated and fully-automated BP measurement. We performed two randomized crossover studies in outpatients visiting a hypertension clinic. The first cohort of 52 participants performed six unattended self-initiated and six fully-automated BP measurements, while continuously monitoring BP and central haemodynamics using finger photoplethysmography. The second cohort consisted of 120 patients who performed three self-initiated and three fully-automated BP measurements. In the first cohort (mean age 61.2 ± 10.4 years, mean office BP 142.0 ± 19.9/82.5 ± 12.2 mmHg, 36.7% female) average systolic and diastolic BP increased by 7.3 ± 8.5/3.3 ± 4.0 mmHg in the group with self-initiated BP measurements, while BP increased by 3.3 ± 6.3/1.4 ± 3.0 mmHg during fully-automated measurements (p = 0.002/p = 0.002 for difference between groups). The higher BP increase during self-initiated BP measurements resulted from an increase in heart rate and cardiac output. In the second cohort (mean age 58.0 ± 14.1 years, mean office BP 153.6 ± 23.8/86.3 ± 14.0 mmHg, 44.1% female) self-initiated BP measurement resulted in a 2.1 ± 6.8/0.9 ± 4.0 mmHg higher systolic and diastolic BP compared with fully-automated self-measurement (p = 0.001/0.018). In conclusion, our findings suggest that self-initiated BP measurement using a fully-automated method results in a more reliable BP compared with a self-initiated semi-automated method by attenuating the auto-cuff response. These findings may have implications for the self-measurement of BP.

Association of sodium and potassium intake with left ventricular mass: coronary artery risk development in young adults

High salt intake may affect left ventricular mass (LVM). We hypothesized that urinary sodium (UNa) and sodium/potassium ratio (UNa/K) are associated with LVM in a predominantly normotensive cohort of young adults. The Coronary Artery Risk Development in Young Adults (CARDIA) Study is a multicenter cohort of black and white men and women aged 30±3.6 years at the time of baseline echocardiographic examination (1990-1991). 2D guided M-mode LVM indexed to body size (grams per meter(2.7)) was calculated, and UNa and potassium excretion assessed (average of three 24-hour urinary samples, n=1042). Linear and logistic regression analysis was used. Participants were 57% women and 55% black. Only 4% were hypertensive. UNa, urinary potassium, and UNa/K ratios were (mean±SD) 175.6±131.0, 56.4±46.3, and 3.4±1.4 mmol/24 h, respectively. Participants in the highest versus the lowest UNa excretion quartile had the greatest LVM (37.5 versus 34.0 g/m(2.7); P<0.001). Adjusted for age, sex, education, and race, LVM averaged 0.945 g/m(2.7) higher per SD of UNa/K (P=0.001). The relationship between UNa/K and LVM persisted among 399 participants with repeat echocardiographic measures 5 years later. In logistic regression analysis adjusted for age, sex, education, and race, each SD higher baseline UNa/K was associated with 23% and 38% greater chances of being in the highest quartile of LVM at baseline (odds ratio: 1.23; P=0.005) and 5 years later (odds ratio: 1.38; P=0.02). A higher sodium/potassium excretion ratio is significantly related to cardiac structure, even among healthy young adults.

Left ventricular mass and ventricular remodeling among Hispanic subgroups compared with non-Hispanic blacks and whites: MESA (Multi-ethnic Study of Atherosclerosis)

OBJECTIVES

The purpose of this study was to examine the prevalence of left ventricular hypertrophy (LVH) and left ventricular (LV) remodeling patterns within Hispanic subgroups compared with non-Hispanic whites in the MESA (Multi-Ethnic Study of Atherosclerosis).

BACKGROUND

Hispanics are the largest and fastest-growing ethnic minority in the U.S., but there are no data on LVH and LV geometry among Hispanic subgroups.

METHODS

Cardiac magnetic resonance imaging was performed in 4,309 men and women age 45 to 84 years without clinical cardiovascular disease. Hispanics were categorized into subgroups based on self-reported ancestry. LVH was defined as the upper 95th percentile of indexed LV mass in a reference normotensive, nondiabetic, nonobese population, and LV remodeling according to the presence/absence of LVH and abnormal/normal LV mass to LV end-diastolic volume ratio.

RESULTS

Among Hispanic participants, 574 were of Mexican origin, 329 were of Caribbean origin, and 161 were of Central/South American origin. On unadjusted analysis, only Caribbean-origin Hispanics (prevalence ratio = 1.2; 95% confidence interval [CI]: 1.03 to 1.4) had greater prevalence of hypertension than non-Hispanic whites. Hispanic subgroups were more likely to have LVH than non-Hispanic whites after adjustment for hypertension and other covariates (Caribbean-origin Hispanics = odds ratio [OR]: 1.8, 95% CI: 1.1 to 3.0; Mexican-origin Hispanics = OR: 2.2, 95% CI: 1.4 to 3.3; Central/South Americans = OR: 1.5, 95% CI: 0.7 to 3.1). All Hispanic subgroups also had a higher prevalence of concentric and eccentric hypertrophy compared with non-Hispanic whites (p < 0.001).

CONCLUSIONS

Caribbean-origin Hispanics had a higher prevalence of LVH and abnormal LV remodeling compared with non-Hispanic whites. A higher prevalence of LVH and abnormal LV remodeling was also observed among Mexican-origin Hispanics, despite a lower prevalence of hypertension. Differences among Hispanic subgroups regarding LVH and LV remodeling should be taken into account when evaluating cardiovascular risk in this population.

Sympathoadrenal stress reactivity is a predictor of future blood pressure: an 18-year follow-up study

In the present study we hypothesized that arterial catecholamine concentrations during rest and 2 laboratory stress tests were independent predictors of blood pressure at an 18-year follow-up. At entry, blood pressure, heart rate, and arterial plasma epinephrine and norepinephrine concentrations were measured in 99 healthy men (age: 19.3+/-0.4 years, mean+/-SD) at rest, during a mental arithmetic test, and during a cold pressor test. After 18.0+/-0.9 years of follow-up, resting blood pressure was measured. The norepinephrine and epinephrine concentrations during the mental arithmetic explained 12.7% of the variation of future systolic blood pressure after adjusting for initial resting blood pressure, family history, body mass index, and systolic blood pressure during the stress test in a multiple regression analysis (adjusted R(2)=0.651; P<0.001). To conclude, the present study shows that sympathetic nervous activity during mental arithmetic predicts future blood pressure, indicating a possible causal factor in the development of essential hypertension independent of the initial blood pressure.

Reactive rise in blood pressure upon cuff inflation: cuff inflation at the arm causes a greater rise in pressure than at the wrist in hypertensive patients

OBJECTIVE

Cuff inflation at the arm is known to cause an instantaneous rise in blood pressure, which might be due to the discomfort of the procedure and might interfere with the precision of the blood pressure measurement. In this study, we compared the reactive rise in blood pressure induced by cuff inflation when the cuff was placed at the upper arm level and at the wrist.

PARTICIPANTS AND METHODS

The reactive rise in systolic and diastolic blood pressure to cuff inflation was measured in 34 normotensive participants and 34 hypertensive patients. Each participant was equipped with two cuffs, one around the right upper arm (OMRON HEM-CR19, 22-32 cm) and one around the right wrist (OMRON HEM-CS 19, 17-22 cm; Omron Health Care Europe BV, Hoofddorp, The Netherlands). The cuffs were inflated in a double random order (maximal cuff pressure and position of the cuff) with two maximal cuff pressures: 180 and 240 mmHg. The cuffs were linked to an oscillometric device (OMRON HEM 907; Omron Health Care). Simultaneously, blood pressure was measured continuously at the middle finger of the left hand using photoplethysmography. Three measurements were made at each level of blood pressure at the arm and at the wrist, and the sequence of measurements was randomized.

RESULTS

In normotensive participants, no significant difference was observed in the reactive rise in blood pressure when the cuff was inflated either at the arm or at the wrist irrespective of the level of cuff inflation. Inflating a cuff at the arm, however, induced a significantly greater rise in blood pressure than inflating it at the wrist in hypertensive participants for both systolic and diastolic pressures (P<0.01), and at both levels of cuff inflation. The blood pressure response to cuff inflation was independent of baseline blood pressure.

CONCLUSIONS

The results show that in hypertensive patients, cuff inflation at the wrist produces a smaller reactive rise in blood pressure. The difference between the arm and the wrist is independent of the patient's level of blood pressure.

Masked hypertension in diabetes mellitus: a potential risk

The prevalence and clinical significance of masked hypertension (MHT) in diabetics have infrequently been described. The authors assessed the association of MHT (defined using a clinic blood pressure [BP] <140/90 mm Hg and daytime ambulatory BP > or = 135/85 mm Hg) with microvascular and macrovascular end organ damage in 81 clinically normotensive Japanese diabetic persons. The prevalence of silent cerebral infarcts (SCIs), increased left ventricular mass, and albuminuria were evaluated. Of 81 patients, 38 (46.9%) were classified as having MHT and showed significantly more SCIs (mean +/- SE: 2.5+/-0.5 vs 1.1+/-0.2; P=.017), and more albuminuria (39% vs 16%; P=.025), but no increase in left ventricular mass index, than the normotensive persons in office and on ambulatory BP monitoring group. The prevalence of MHT in this diabetic population was high (47%). Diabetic patients with MHT showed evidence of brain and kidney damage. Hence, out-of-office monitoring of BP may be indicated in diabetics whose BP is normal in the clinic.

Metabolic syndrome in subjects with white-coat hypertension: impact on left ventricular structure and function

Some reports have suggested that white-coat hypertension (WCH) is associated with some features of the metabolic syndrome (MetS). These metabolic disturbances, instead of WCH per se, may potentially explain the greater extent of end-organ damage sometimes observed in WCH subjects (WCHs) when compared to normotensive individuals (NTs). The aim of the present cross-sectional study was to compare left ventricular (LV) structure and function in three groups of subjects: WCHs with MetS, WCHs without MetS and NTs. A total of 145 WCHs, 35% of whom had MetS, were enrolled. As controls, 35 NTs were also studied. In all subjects, routine blood chemistry, echocardiographic examination and 24-h ambulatory blood pressure monitoring were performed. When compared with WCHs without MetS, those with MetS showed higher LV mass indexed by height elevated by a power of 2.7 (LVMH(2.7)) (49.6+/-14.8 vs 38.9+/-9.8 g/m(2.7); P<0.0001). The same parameter was greater in WCHs without MetS than in NTs (32+/-8 g/m(2.7); P=0.004). Moreover, the E-wave deceleration time was longer in WCHs with MetS than in those without it (236.2+/-66.4 vs 200.5+/-30.8 ms; P<0.0001). The relationship of MetS with LVMH(2.7) was confirmed in multivariate regression models. Our results seem to suggest that MetS may have a deleterious influence on LV structure and function in WCH. However, WCH, being associated with an increased LV mass, also in subjects without MetS, may not be considered as an innocuous phenomenon.

Aortic Elastic Properties in Patients With Hypertensive Response to Exercise

BACKGROUND

The aim of this study was to evaluate whether there is a relationship between aortic elastic properties in patients with a suggestive response to treadmill exercise testing.

METHODS AND RESULTS

The study group comprised 32 patients suggesting hypertensive response to exercise and 20 patients suggesting normal blood pressure response to treadmill exercise testing. Baseline demographic characteristics were similar in both groups. However, the mean aortic stiffness index of patients suggesting hypertensive response to treadmill exercise testing was significantly higher (4.8+/-1.26 vs 2.36+/-1.09; p=0.001) whereas aortic distensibility was significantly lower (12.82 +/-5.84 vs 22.64+/-14.54; p=0.001) than the control group. The aortic strain of patients with hypertensive response to exercise was lower than the control group (12+/-3% vs 19.2+/-5%, p<0.001). The left ventricular mass (LVM) of these patients was also higher than control group (206.5+/-46.3 vs 134.2+/-19.97; p=0.01). A negative correlation between LVM and distensibility was found (r=-0.64; p=0.001) well as a positive correlation between LVM and aortic stiffness index (r=0.51; p=0.004) in patients suggesting hypertensive response to exercise. Pressure--rate product was also found to be correlated with LVM (r=0.47; p=0.006).

CONCLUSION

Elastic properties of the aorta may be impaired in subjects showing exaggerated blood pressure response to exercise long before clinically manifest hypertension, particularly if the LVM is increased.

Can we improve cardiovascular risk prediction beyond risk equations in the physician's office?

BACKGROUND AND OBJECTIVES

Beyond a global estimation of the cardiovascular risk through the assessment of major risk factors and their integration in dedicated risk scales or equations, the use of specific markers provides additive prognostic information at an individual level, including predisposing factors, which are not included in the risk equations as well as the individual susceptibility to their long-term exposure. However, the majority of these markers require specific devices and skills, which are not widely available in primary care.

METHODS

Some clinical and/or "low-cost" parameters are shown to be valuable risk markers, and their use could refine the risk estimation in a physician's office. Several epidemiologic studies suggest the heart rate, the pulse pressure and the ankle-brachial index are effective cardiovascular risk markers. The arms systolic pressure asymmetry could also be a useful marker of risk.

RESULTS AND CONCLUSIONS

Through a general review, the authors evaluate the potential of these clinical markers, including their use in combination for more accurate risk determination.

Cardiovascular intraindividual variability in later life: the influence of social connectedness and positive emotions

Healthy normotensive men and women (N=33) underwent a 60-day diary assessment of emotions and cardiovascular functioning. Individual differences in social connectedness and mood were measured in questionnaires, and positive emotions, negative emotions, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were assessed daily for 60 consecutive days. Results confirmed that the cardiovascular undoing effect of positive emotions is evident primarily in the context of negative emotional arousal. The daily associations between positive emotions and cardiovascular outcomes were linked to individual differences in social connectedness. Controlling for individual differences in mood levels, multilevel regression analyses showed that social connectedness predicted extended positive emotion, diminished SBP and DBP reactivity, and more rapid SBP recovery from daily negative emotional states.

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.

Sympathetic activity and cardiovascular risk factors in young men in the low, normal, and high blood pressure ranges

We hypothesized that resting blood pressure is related to sympathetic activity in young men who are unaware of their blood pressure status in high, normal, and low ranges and that there is a relationship between sympathetic activity and coronary risk factors. Forty-three healthy, young men from the 1st [group 1, 106/52+/-2/2 mm Hg (+/-SEM), n=15], 50th (group 2, 129/79+/-2/1 mm Hg, n=15), and 98th to 99th percentile (group 3, 166/97+/-3/1 mm Hg, n=13) at a blood pressure screening were studied with intraarterial blood pressure, heart rate, and arterial plasma catecholamine responses to a mental, cold pressor, and orthostatic stress test. At baseline, group 3 had significant higher blood pressure (137/74+/-3/2 mm Hg) than group 2 (126/66+/-3/2 mm Hg; P<0.01) and group 1 (116/62+/-2/1 mm Hg; P<0.001). Group 1 had lower systolic blood pressure than group 2 (P=0.007). Baseline epinephrine and norepinephrine showed a clear positive linear trend (P<0.05), with the lowest values being in group 1 and highest in group 3. High-density lipoprotein was negatively related to epinephrine (r=-0.387; P=0.010). Mental stress was the only test that showed significant differences in cardiovascular and sympathetic responses among the groups, where group 3 had a more pronounced response in systolic and diastolic blood pressure and heart rate compared with group 1 (P<0.001) and group 2 (P<0.01). Furthermore, we found significant positive linear trends for Deltacatecholamines during mental stress across the groups (Deltaepinephrine P=0.001 and Deltanorepinephrine P=0.026, ANOVA). We conclude that resting blood pressure reflects both variation in resting arterial catecholamines and variation in cardiovascular and sympathetic responses specifically to mental stress.

Regulation of the catecholamine beta-adrenergic system in ventricular remodeling of hypertension

Differences in structural remodeling are believed to be influenced by hormonal systems in hypertension. The objective of the present study was to investigate the change in the circulating catecholamine beta-adrenergic system in the left ventricle remodeling process in hypertensives. One hundred and thirty-four men (mean age, 53 years) had essential hypertension and underwent echocardiography before treatment. Normal morphology (n = 26) and concentric remodeling (n = 41) were defined by a relative wall thickness at diastole (RWT) of < 0.44 and > or = 0.44, respectively, and concentric hypertrophy (n = 28) and eccentric hypertrophy (n = 39) by a left ventricular mass index (LVMI) of < 150 g/m(2) and > or = 150 g/m(2), respectively. Forty healthy males were studied as normal controls. Plasma levels of norepinephrine (NE) and epinephrine (E) were measured by high performance liquid chromatography. The density of lymphocyte beta-adrenoceptors (beta-AR) and the content of intralymphocyte cyclic AMP (cAMP) in peripheral blood were measured using (3)H-dihydroalpneol as a ligand and protein binding assay, respectively. The plasma levels of NE and E in the 4 groups of patients with essential hypertension were significantly increased compared with the control group. The density of lymphocyte beta-AR and the content of intralymphocyte cAMP of peripheral blood in the normal morphology, concentric remodeling, and concentric hypertrophy groups were significantly higher than those in the control group, while the values in the eccentric hypertrophy group were significantly lower than those in the control group. Among the 4 groups, the plasma levels of NE and E had increased the most in the normal morphology group, followed in decreasing order by the concentric remodeling, concentric hypertrophy, and eccentric hypertrophy groups; the density of lymphocyte beta-AR and the content of intralymphocyte cAMP of peripheral blood in the normal morphology, concentric remodeling, and concentric hypertrophy groups increased while they decreased in the eccentric hypertrophy group in patients with essential hypertension. The catecholamine beta-adrenergic system appears to be related to left ventricular remodeling of hypertension. In this process, catecholamines increased continually. The density of beta-AR and the content of cAMP in peripheral lymphocytes increased at first and then decreased.

Changes and significance of subtype function of beta-adrenoreceptors in left ventricular remodeling of hypertension

Changes in the density of myocardium and blood lymphocyte beta-adrenoceptors (beta-AR) in left ventricular (LV) geometry have been found in patients with essential hypertension (EH). However, it is not known whether intrinsic beta-AR subtype function changes during left ventricular remodeling of hypertension. The purpose of this study was to further investigate the changes and clinical significance of beta-AR subtype function in LV remodeling in patients with EH. One hundred and thirty-four men (mean age, 53 years) with EH as defined in the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure grades 1 to 2 and 40 normotensives were studied. Based on the echocardiographic LV mass index and relative wall thickness, four patterns of LV geometry, ie, normal left ventricle, concentric remodeling, eccentric hypertrophy, and concentric hypertrophy were identilied. beta-Adrenoreceptor subtype responsiveness was measured by a treadmill exercise test (to measure cardiac beta1-adrenoreceptor responsiveness) and by Salbutamol injection test (to measure cardiac beta2-adrenoreceptor responsiveness) in 134 male patients with EH. Forty normotension subjects were also studied as controls. In patients with EH in the groups of concentric remodeling, concentric hypertrophy, and eccentric hypertrophy, heart rate in response to the treadmill test (peak exercise-resting rate) was significantly higher (P < 0.05, P < 0.01. P < 0.01, respectively) than that in the control group. In the concentric remodeling and concentric hypertrophy group, the chronotropic doses of salbutamol required to increase the heart rate by 30 beats/min (CD30) were significantly lower (P < 0.05, P < 0.01, respectively) than that in the control group. However, in the eccentric hypertrophy group. CD30 was higher significantly (P < 0.01) than that in the control group. In the concentric remodeling, concentric hypertrophy, and eccentric hypertrophy groups, beta1-AR responsiveness significantly increased them in the normotensive group, whereas beta2-AR responsiveness significantly increased in the concentric remodeling and concentric hypertrophy groups them in the normotensive group, and significantly decreased in the eccentric hypertrophy them in the normotensive group. The results suggest that non-beta-selective blocker may be beneficial for normal morphology, concentric remodeling and concentric hypertrophy, while beta1-selective blockers may be beneficial for eccentric hypertrophy in patients with EH.

Cardiovascular reactivity and left ventricular mass: An integrative review

Left ventricular hypertrophy has been shown to be an independent predictor of risk for cardiovascular morbidity and mortality. Behavioral scientists have focused on how hemodynamic factors influenced by psychosocial stress may be associated with left ventricular mass (LVM). We reviewed existing studies examining stress-related cardiovascular reactivity (CVR) and LVM, with a goal of examining the moderating role of population (age and hypertensive status) and methodological factors (task type, sample size, and study design) explaining the observed results. Twenty-one studies met the criteria for this review. Results showed only a modestly consistent relationship between CVR and LVM. Forty-three percent of the studies reported 1 or more significant results linking systolic blood pressure reactivity with LVM, and 14% of the studies showed that diastolic blood pressure reactivity was significantly related to LVM. Hypertensive status, task type, and sample size did not play a major role in moderating the relationship between LVM and CVR. A somewhat larger percentage of positive results was shown in prospective and adult studies. The association between CVR and LVM may be real, although the effect size is modest, and we discuss methodological strategies for enhancing statistical power in future investigations. Additional sampling factors (e.g., race, gender) may also impact this relationship. Finally, greater attention is warranted to the role of the psychosocial environment, as this may interact with reactivity to influence LVM.

Pulse pressure responses to psychological tasks improve the prediction of left ventricular mass: 10 years of follow-up

OBJECTIVES

To examine the role of casual blood pressure measurements and blood pressure responses to psychological tasks in the prediction of future left ventricular mass index (LVMI), and to determine the importance of different components of blood pressure, and the predictive value of an individual's personal characteristics and antihypertensive medication on future LVMI.

METHODS

At baseline, blood pressure was recorded by casual measurements; during tests it was recorded by intra-arterial monitoring. The participants were healthy, untreated 35-45-year old men. Echocardiography data both at baseline and after 10 years of follow-up were available from 65 individuals, of whom 49 (75%) were not taking antihypertensive medication at follow-up. Those not taking antihypertensive medication were included in the prediction of LVMI (g/m2).

RESULTS

Baseline LVMI correlated significantly with future LVMI only among the 49 unmedicated individuals (r = 0.52, P < 0.0001). The predictive value of baseline LVMI on future LVMI among them (adjusted coefficient of determination = 0.26) was not improved by the inclusion of casual blood pressure. In contrast, blood pressure responses to the psychological tasks improved the prediction of future LVMI by 4-13%. Pulse pressure was the blood pressure variable that entered the final prediction models; the correlations with future LVMI were best for pulse pressure response to habituation task (r = 0.43, P < 0.05) and to relaxation (r = 0.37, P < 0.05).

CONCLUSIONS

To our knowledge, this is the longest prospective follow-up to show that blood pressure responses to psychological tasks improve the prediction of LVMI compared with casual blood pressure measurements. The pulse pressure, which reflects the properties of the arterial wall, is the most significant blood pressure variable in predicting future LVMI.

Relationship of clinic, ambulatory, and laboratory stress blood pressure to left ventricular mass in overweight men and women with high blood pressure

OBJECTIVE

This study was designed to evaluate the relationship between left ventricular (LV) mass and blood pressure (BP) recorded in the following contexts: in the clinic, using standard auscultatory procedures, during a typical day using ambulatory BP monitoring, and in the laboratory environment during behavioral stress testing.

METHODS

Ninety-seven men and women with clinic systolic blood pressure (SBP) of 130 to 180 mm Hg and/or diastolic blood pressure (DBP) of 85 to 110 mm Hg and mild to moderate obesity were included in the study. Laboratory stressors included the following tasks: Public Speaking; Anger Interview; Mirror Trace; and Cold Pressor. LV mass was measured using echocardiography and adjusted for body size by dividing by height(2.7) to yield LV mass index (LVMI).

RESULTS

LVMI was positively correlated with clinic SBP (r = 0.24, p <.05), ambulatory SBP (r = 0.34, p <.01), and aggregated laboratory stress SBP (r = 0.28, p <.01). Of the individual stressors, only SBP responses to the Mirror Trace and Cold Pressor tasks were independently correlated with LVMI (r = 0.35 and 0.34, respectively, p values <.01). Hierarchical regression analyses revealed that laboratory stress SBP remained a significant predictor of LVMI, after controlling for BMI and clinic pressure.

CONCLUSIONS

These findings suggest that cardiovascular responses to behavioral stress are associated with individual differences in LVMI in men and women with high blood pressure who are overweight. Laboratory studies of behavioral stress may help promote our understanding of the pathophysiology of LVH.

Prognostic significance of blood pressure measured on rising

Previous works using ambulatory blood pressure (BP) monitoring demonstrated that independently of the mean level of BP, the variability in BP, or the day-night range, could have prognostic significance. We have also found that the value of BP on rising in the morning is strongly correlated with left ventricular mass of hypertensive individuals independently of the 24-h value. In the present study, we sought its predictive value for cardiovascular complications in a cohort of hypertensive patients. The population studied belongs to a cohort of initially untreated hypertensive patients recruited since 1983 and followed for more than 5 years. Patients were then treated and followed by their family doctor. At entry, all patients were equipped with a device to measure ambulatory BP. They were requested to trigger a measurement manually on rising in the morning (arising BP). The data on their outcome were collected by a physician unaware of the initial state of the patients. A total of 256 patients have been followed up for 5 years or more, 19 were lost to follow-up. The mean follow-up period was 84 +/- 29 months. Cardiovascular complications were recorded in 23 individuals. The arising systolic BP (SBP) was significantly higher in the group who presented a complication. In a stepwise discriminant analysis including age, office, fitting, arising and 24-h average SBPs only age and arising SBP entered the equation. In conclusion, the single BP value measured by an ambulatory device on rising in the morning seems more discriminant of future cardiovascular events than the value of BP measured on fitting the device or the average of three measurements taken under standardised conditions in the hospital or office.

Anticipatory blood pressure responses to exercise are associated with left ventricular mass in Finnish men: Kuopio Ischemic Heart Disease Risk Factor Study

BACKGROUND

Exaggerated cardiovascular reactivity to psychological demands may contribute to the development of left ventricular (LV) hypertrophy. We examined the cross-sectional association between anticipatory blood pressure (BP) responses to bicycle exercise and LV mass in the Kuopio Ischemic Heart Disease Risk Factor Study, a population-based epidemiological sample.

METHODS AND RESULTS

Among 876 men from 4 age cohorts (ages 42, 48, 58, and 64 years), we collected echocardiographic assessments of LV mass along with measures of BP response taken before bicycle ergometry testing. Anticipatory BP responses were positively associated with LV mass, with significant associations only among younger (age <50 years) subjects with elevated resting pressures (3-way interactions for anticipatory BP x age x resting pressure for systolic and diastolic BP, all P:<0.05; for younger subjects with elevated systolic BP, P:<0. 01; and for younger subjects with elevated diastolic BP, P:<0.001). Among these subgroups, exaggerated anticipatory BP responses (top quartile) were associated with an incremental increase in LV mass of 10% or greater, corrected for body surface area. Results remained significant after adjusting for age, education, salt consumption, and resting BP, and the pattern of findings was maintained among men with no previous history of cardiovascular disease.

CONCLUSIONS

The tendency to show exaggerated pressor responses to psychological demands may be a significant independent correlate of LV mass, especially among young men with high resting pressures. This is the first study to examine such associations in a middle-aged population sample.

The changing face of sympathetic overactivity in hypertension

There is a lot of evidence showing that sympathetic activity is increased in a large proportion of patients with hypertension. However, the clinical impact of this state is frequently underestimated. Several factors seem to be misunderstood, such as whether sympathetic overactivity is reproducibly present, whether it lasts throughout 24 h, and what is the significance of its association with tachycardia. In this review, we present data to indicate that several haemodynamic changes in hypertension such as elevated cardiac output and heart rate and alteration in vascular resistance are neurogenic. The relationship between the increased sympathetic tone and decreased parasympathetic tone in hypertension is reciprocal, which strongly suggests that the abnormality emanates from the brain. The increase in sympathetic drive in hypertension is widespread across many organs. Beside the heart it is seen in the kidney and skeletal muscle, and even in platelets. We also discuss the possible mechanisms of the haemodynamic transition from this hyperkinetic state to established hypertension. We propose a hypothesis where down-regulation of beta-adrenergic responsiveness plays a major role in explaining the haemodynamic changes as well as metabolic alterations, such as hyperinsulinaemia and even the gain of weight in hypertension. Thus, the increased sympathetic tone may be involved in the genesis of multiple, pressure-independent coronary risk factors in hypertension.

Left ventricular concentric remodeling rather than left ventricular hypertrophy is related to the insulin resistance syndrome in elderly men

BACKGROUND

Associations between left ventricular (LV) geometry and the insulin resistance syndrome have been found, mostly in small studies of middle-aged hypertensives. The purpose of this study was to elucidate these associations through the use of a large sample of elderly men.

METHODS AND RESULTS

We investigated 475 men (157 hypertensives) 71 years of age who were attending a population-based health survey in Uppsala County with echocardiography, oral glucose tolerance test (OGTT), hyperinsulinemic euglycemic clamp, and lipid and 24-hour ambulatory blood pressure monitoring. LV relative wall thickness was significantly related to clamp insulin sensitivity index (r=-0.14), fasting insulin, 32-33 split proinsulin, triglycerides, nonesterified fatty acids, OGTT glucose and insulin levels, waist-to-hip ratio, body mass index, 24-hour blood pressure, and heart rate (r=0.10 to 0.22). Only 24-hour systolic pressure (r=0. 15), OGTT 2-hour insulin (r=-0.10), and heart rate (r=-0.14) were significantly related to LV mass index. Comparing subjects with various LV geometry (normal, concentric remodeling and concentric and eccentric hypertrophy) showed that 24-hour heart rate, OGTT glucose and insulin levels, waist-to-hip ratio, and body mass index were significantly higher (P<0.001 to 0.05) and clamp insulin sensitivity index was significantly lower (P<0.01) in the concentric remodeling geometry group than in the normal LV geometry group. The 24-hour blood pressure was significantly higher in the concentric hypertrophy group than in the normal LV geometry group (P<0.001).

CONCLUSIONS

Several components of the insulin resistance syndrome were related to thick LV walls and concentric remodeling but less to LV hypertrophy in this population-based sample of elderly men.

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.

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.

Relevance of heart rate as a risk factor in hypertension

Numerous studies have shown that resting heart rate is closely correlated with blood pressure and that it is prospectively related to the development of hypertension. Moreover, there is mounting evidence to indicate that a high heart rate is associated with increased cardiovascular morbidity and mortality. In this respect, heart rate can be considered both as a marker of risk and as an independent factor in the induction of risk. Sympathetic overactivity seems to be responsible for the increase in blood pressure and hematocrit, and for the metabolic abnormalities often observed in subjects with tachycardia. Experimental studies in monkeys have shown that heart rate can also exert a direct atherogenic action on the arteries through increased wall stress. Furthermore, tachycardia can favor the occurrence of ventricular arrhythmias and sudden death. Reduction of heart rate appears to be a reasonable additional goal of antihypertensive therapy, especially in subjects with increased sympathetic tone. Nondihydropyridine calcium antagonists and drugs with agonistic properties at the I1-imidazoline receptors of the rostral ventrolateral medulla may be drugs of choice for this purpose, but whether they offer a significant morbidity-mortality advantage must be proven in prospective trials.

Heart rate as a risk factor for atherosclerosis and cardiovascular mortality: the effect of antihypertensive drugs

The aim of this review is to highlight the importance of heart rate (HR) as a risk factor for cardiovascular disease, and to discuss the classes of drugs which can be potentially useful in clinical conditions in which an elevated HR may be present. Numerous studies have shown that high resting HR is prospectively related to the development of atherosclerosis and of cardiovascular events. This relationship was independent of other major risk factors for atherosclerosis and was observed in the general population, in elderly people, in hypertensive cohorts and in patients with myocardial infarction or heart failure. The clustering of several risk factors in individuals with fast heart rate may explain why cardiovascular morbidity is higher in individuals with tachycardia. Sympathetic overactivity seems to be responsible for both the increase in HR, blood pressure and the metabolic abnormalities. Experimental studies in monkeys have shown that HR can also exert a direct atherogenetic action on the arteries through increased wall stress. Moreover, tachycardia can favour the occurrence of ventricular arrhythmias and sudden death. Reduction of HR appears as an additional goal of antihypertensive therapy. If fast HR in hypertension is a marker of increased sympathetic tone, agents which decrease HR through a decline of sympathetic outflow should be particularly efficacious. Beta-blockers retard the development of coronary atherosclerosis in cholesterol-fed monkeys and have proven to be beneficial in patients with myocardial infarction or with heart failure, but their efficacy appear limited in hypertension, probably on account of their unfavourable metabolic profile. Phenylalkylamines are devoid of this untoward effect, and seem to act also through inhibition of sympathetic discharge from the CNS. Mibefradil, a more recent calcium antagonist that selectively blocks voltage-dependent T-type calcium channels decreases HR without affecting left ventricular contractility. New drugs with agonistic properties at the I1-imidazoline receptors of the rostral ventrolateral medulla are effective in reducing blood pressure and HR by inhibiting the sympathetic outflow and improved metabolic parameters in obese or fructose-fed rats. The goal of antihypertensive therapy in the future will be to prevent or reverse those functional abnormalities which accompany the hypertensive condition. In patients with tachycardia the reduction of HR appears a desirable additional goal of therapy.

Hypertension and the development of heart failure

Hypertension is a well-known risk factor that predisposes to the development of left ventricular hypertrophy, coronary flow abnormalities, and systolic and diastolic dysfunction. This complex of abnormalities is known as hypertensive heart disease and eventually leads to heart failure. Structural lesions underlying this process include excess deposition of collagens and cellular infiltration, with an increase in the size of cardiac myocytes (remodeling). The occurrence of arteriolar lesions may lead to impediments of flow. Clinically, hypertensive heart disease manifests itself by anginal complaints and sometimes by silent ischemia, arrhythmias, and sudden death. Alterations in systolic and/or diastolic function may be associated with symptoms of heart failure. Although successful treatment of hypertension can probably retard the process of cardiac impairment, there is as yet no evidence that heart failure can be prevented.

Cardiorenal effects of behavioral inhibition of breathing

This article reviews evidence that mild, but sustained, inhibition of breathing can affect blood pressure regulation via effects of increased PCO2 on sodium regulation. Experiments with micropigs are summarized which show that anticipation of the onset of a familiar avoidance task is accompanied by sustained increases in PCO2, increases in plasma hydrogen and bicarbonate ion concentrations, decreases in hematocrit, and increases in circulating levels of sodium pump inhibitors that are sensitive to plasma volume. Observational studies with humans using an ambulatory respiration monitor characterize episodes of inhibited breathing occurring in the natural environment. Experimental studies with human subjects show that voluntary maintenance of end-tidal CO2 near the upper end of the normal range results in decreases in renal sodium excretion, increases in plasma sodium pump inhibitors and inhibition of sodium pump activity. Together, these studies are consistent with the view that behavioral stress can influence blood pressure regulation via sustained inhibition of respiration which acidifies the plasma and increases sodium/hydrogen exchange in kidneys and blood vessels.

Target-organ damage in stage I hypertensive subjects with white coat and sustained hypertension: results from the HARVEST study

Controversy remains on whether white coat hypertension is a benign clinical condition or carries an increased risk of target-organ damage. Nine hundred forty-two stage I hypertensive subjects enrolled in the HARVEST trial underwent 24-hour ambulatory blood pressure monitoring and urine collection for albumin measurement. Reliable echocardiographic data were obtained in 722 subjects. White coat hypertensive subjects were defined on the basis of three different partition values: mean daytime blood pressure <130/90 mm Hg, <135/85 mm Hg, or <140/90 mm Hg. Ninety-five normotensive subjects with similar age and sex distribution were studied as controls. With all threshold levels, left ventricular mass index and wall thicknesses were greater in the sustained hypertensive subjects than in the white coat hypertensive subjects, also when these differences were adjusted for blood pressure readings taken in the office. Relative wall thickness was similar in the two hypertensive groups. All echocardiographic dimensional data were greater in the white coat hypertensive subjects than in the normotensive subjects. Urinary albumin and the prevalence of microalbuminuria were also greater in the sustained hypertensive subjects than in the white coat hypertensive subjects. No significant differences in urinary albumin were found between the white coat hypertensive and the normotensive subjects. These results show that within a population of subjects with stage I hypertension, subjects with white coat hypertension have a smaller degree of hypertensive complications than those with sustained hypertension, irrespective of their blood pressure levels taken in the office. However, in comparison with normotensive subjects, white coat hypertensive subjects seem to be at greater risk. Cardiac involvement seems to precede glomerular damage in the early stage of hypertension.

Racial differences in the prevalence of left ventricular hypertrophy among chronic cocaine abusers

There are racial differences in the prevalence and pattern of left ventricular (LV) hypertrophy in hypertension. This study was performed to determine whether racial differences also exist in LV hypertrophy among chronic cocaine users. We studied 112 chronic cocaine abusers < 45 years old in whom normal blood pressures (< or = 140/90 mm Hg) were recorded 3 times daily for 3 weeks. LV wall thickness and mass were measured echocardiographically. Technically adequate studies were obtained in 79 blacks and 33 whites. Self-reported cocaine use was higher in whites than in blacks (688 +/- 516 vs 431 +/- 468 $/week, p = 0.03). There were no group differences in terms of duration of cocaine use, age, height, weight, blood pressure, LV dimensions, or left atrial size. However, posterior wall thickness (1.13 +/- 0.17 vs 1.03 +/- 0.14 cm, p = 0.0035) and LV mass index (113 +/- 25 vs 94 +/- 19 g/m2, p = 0.0001) were significantly greater in blacks. LV hypertrophy, defined as an M-mode LV mass index > or = 134 g/m2, was present in 24 blacks (30%) and 2 whites (6%) (p = 0.011). When defined as a posterior wall thickness > or = 1.2 cm and a 2-dimensional echocardiographic LV mass index > or = 105 g/m2, LV hypertrophy was present in 37 of 79 blacks (47%) and in 6 of 33 whites (18%) (p = 0.0086). Cocaine-related LV hypertrophy is more prevalent in black men than in white men.(ABSTRACT TRUNCATED AT 250 WORDS)

Refeeding hypertension in obese spontaneously hypertensive rats

Very-low-calorie diets lower blood pressure acutely in obese humans and rats. However, refeeding after dietary restriction produces mild hypertension in rats. Refeeding hypertension was characterized in genetically obese spontaneously hypertensive rats (obese SHR, Koletsky rat), a model of genetic obesity and hypertension. Obese SHR were fed a restricted diet (Optifast) for 12 days, refed ad libitum for 28 days, dieted again for 12 days, and then refed 4 days and killed. Control obese SHR and lean SHR littermates were fed ad libitum continuously. Dietary restriction led to rapid weight loss followed by prompt regain to baseline weight after return to unrestricted food intake. Heart rate fell with institution of the low-calorie diet and returned to baseline on refeeding. Blood pressure became elevated during refeeding in dieted obese SHR relative to ad libitum fed obese SHR controls. The fall in blood pressure after ganglionic blockade with chlorisondamine was exaggerated in refed obese SHR, and cardiac beta-adrenergic receptors were downregulated. Both of these findings imply increased sympathetic tone. The left ventricular wall was thicker in the refed obese SHR than in the ad libitum fed obese SHR. Shorter cycles of weight loss and regain in lean SHR led to transient increases in blood pressure and heart rate. Cycles of dietary restriction and refeeding in obese SHR elicit sustained blood pressure elevation via sympathetic activation and exacerbate cardiac hypertrophy. Drastic fluctuations in nutrient intake may not be advantageous in hypertension.

Sex-specific determinants of increased left ventricular mass in the Tecumseh Blood Pressure Study

BACKGROUND

Left ventricular hypertrophy (LVH) defined by either ECG or echocardiographic criteria is a risk factor for cardiovascular morbidity and mortality. A number of determinants of LVH have been described in previous studies, principally male sex, hypertension, obesity, and aortic valvular stenosis. We examined the distribution of LV mass (LVM) in a population of 18- to 42-year-old normotensive men and women who were free of valvular heart disease to establish sex-specific normal values for LVM index (LVMI) and to determine the correlates of LVMI.

METHODS AND RESULTS

LVM was derived from measurements obtained by M-mode echocardiography. Average LVMI is significantly greater in men (102.9 +/- 0.7 g/m2) than women (88.2 +/- 0.7 g/m2). By defining LVH as an LVMI greater than the 90th percentile, we developed sex-specific criteria for LVH: men, > 125.4 g/m2; women, > 110 g/m2. We found that LVH in men is associated with indices of enhanced sympathetic nervous system reactivity and with elevated fasting insulin and triglyceride levels, which may be caused by insulin resistance. In women, LVH was associated with higher body weight and obesity.

CONCLUSIONS

Before the onset of hypertension, increased LVMI appears to have different determinants in men and women. We suggest that early LVH in young men is a manifestation of hyperkinetic borderline hypertension, a state previously shown to be associated with increased sympathetic nervous system activity and insulin resistance. The hyperkinetic state is less prevalent in young women, in whom increased adiposity seems to be the predominant factor associated with LVH.

Salt intake, blood pressure, and cardiovascular structure

Epidemiologic data revealed that a low sodium intake might have a favorable influence on blood pressure throughout an individual's lifetime. Sodium restriction was reported to lead to a modest fall in blood pressure in some studies, although a few groups of hypertensive patients experienced a rise in blood pressure. Left ventricular hypertrophy has been demonstrated to be related to cardiovascular morbidity and mortality independent of other risk factors. Dietary salt intake participates in the hypertrophic process independent of other determinants. Thus, 24-hour urinary sodium excretion has been reported to correlate with left ventricular mass independent of levels of arterial pressure. Three different mechanisms may link dietary salt intake to myocardial hypertrophy: the renin-angiotensin-aldosterone system, the sympathetic nervous system, and fluid volume homeostasis. Whether salt restriction reduces cardiovascular structural damage independent of arterial pressure has not been determined.

The effect of hypertensive episodes and cardiac hypertrophy on the canine cardiac baroreflex

1. Left ventricular (LV) hypertrophy has been implicated in the reduction of baroreflex sensitivity present in hypertension. The aim of the current study was to investigate the mean arterial pressure-heart rate reflex (MAP-HR) in a model which induced left ventricular hypertrophy but no sustained blood pressure elevation. 2. Five mongrel dogs were exposed to transient blood pressure elevation of between 20 and 30 mmHg, through hindlimb compression using a pneumatic pressure suit, for 7 h per day, 6 days per week for 6 weeks. Resting blood pressure was not altered by the 6 week hindlimb compression intervention. 3. Echocardiographically determined LV mass (mean +/- s.e.m.) was 116.0 +/- 7.4 g prior to hindlimb compression (baseline) and elevated to 125.4 +/- 8.1 g (P = 0.003) after 6 weeks of compression. A reduction in the early (E) to late (A) transmitral diastolic flow ratio (E/A) from 1.80 +/- 0.06 at baseline to 1.54 +/- 0.09 (P = 0.037) after the 6 week intervention suggested that cardiac compliance was reduced. 4. The maximum gain of the MAP-HR reflex, studied using the 'steady-state' drug technique, when blood pressure was normal, showed a trend for reduction from 3.85 +/- 0.43 beats/min per mmHg at baseline to 3.10 +/- 0.45 beats/min per mmHg (P = 0.067) after 6 weeks of compression. This gain reduction became significant after beta-adrenoceptor blockade with propranolol (3.13 +/- 0.55 vs 2.32 +/- 0.25 beats/min per mmHg; P = 0.039). Covariant analysis showed a significant inverse correlation between LV mass and maximum gain (r = 0.96; P < 0.001) during the 6 week compression period.(ABSTRACT TRUNCATED AT 250 WORDS)

Is white coat hypertension innocent? Structure and function of the heart in the elderly

To evaluate the morphological and functional characteristics of the heart in elderly patients with white coat hypertension, we performed an echocardiographic study in 67 elderly individuals older than 60 years: 17 patients with white coat hypertension, 34 patients with true hypertension, and 16 normotensive control subjects. White coat hypertension was defined as a mean 24-hour ambulatory systolic blood pressure of less than 140 mm Hg associated with office hypertension. Cardiac responses to an isometric handgrip exercise test were used to evaluate left ventricular functional reserve. Left atrial dimension and left ventricular mass index were significantly greater in the white coat hypertension group than in the normotension group (P < .05) but were similar to values in the true hypertension group. Left ventricular diastolic function, expressed by peak late-early filling ratio of diastolic mitral flow, showed increasing impairment in the order of the normotension, white coat hypertension, and true hypertension groups (analysis of variance, P < .05); the ratio in the white coat hypertension group tended to be higher than that in the normotension group (unpaired t test, P = .054). The relation between fractional shortening and end-systolic stress did not shift downward after handgrip exercise in the white coat hypertension group, indicating that functional reserve in the left ventricle was maintained. Thus, patients with white coat hypertension had a moderately increased left atrial dimension and left ventricular mass in association with a tendency for disturbed diastolic function, although systolic functional reserve remained the same. These findings suggest that white coat hypertension in the elderly may not be innocent.