The Bergen Blood Pressure Study: prehypertensive changes in cardiac structure and function in offspring of hypertensive families

Prenatal and Postnatal Cardiac Development in Offspring of Hypertensive Pregnancies

Background

Pregnancy complications such as preterm birth and fetal growth restriction are associated with altered prenatal and postnatal cardiac development. We studied whether there were changes related specifically to pregnancy hypertension.

Methods and Results

Left and right ventricular volumes, mass, and function were assessed at birth and 3 months of age by echocardiography in 134 term‐born infants. Fifty‐four had been born to mothers who had normotensive pregnancy and 80 had a diagnosis of preeclampsia or pregnancy‐induced hypertension. Differences between groups were interpreted, taking into account severity of pregnancy disorder, sex, body size, and blood pressure. Left and right ventricular mass indexed to body surface area (LVMI and RVMI) were similar in both groups at birth (LVMI 20.9±3.7 versus 20.6±4.0 g/m², P=0.64, RVMI 17.5±3.7 versus 18.1±4.7 g/m², P=0.57). However, right ventricular end diastolic volume index was significantly smaller in those born to hypertensive pregnancy (16.8±5.3 versus 12.7±4.7 mL/m², P=0.001), persisting at 3 months of age (16.4±3.2 versus 14.4±4.8 mL/m², P=0.04). By 3 months of age these infants also had significantly greater LVMI and RVMI (LVMI 24.9±4.6 versus 26.8±4.9 g/m², P=0.04; RVMI 17.1±4.2 versus 21.1±3.9 g/m², P<0.001). Differences in RVMI and right ventricular end diastolic volume index at 3 months, but not left ventricular measures, correlated with severity of the hypertensive disorder. No differences in systolic or diastolic function were evident.

Conclusions

Infants born at term to a hypertensive pregnancy have evidence of both prenatal and postnatal differences in cardiac development, with right ventricular changes proportional to the severity of the pregnancy disorder. Whether differences persist long term as well as their underlying cause and relationship to increased cardiovascular risk requires further study.

Left Ventricular Myocardial Performance in Normotensive Offspring of Hypertensive Parents

INTRODUCTION

Early alterations in the cardiovascular system have been described in offspring of hypertensive parents, but with conflicting results.

AIM

To evaluate the influence of genetic predisposition to hypertension on left ventricular (LV) geometry and function, 30 normotensive male offspring of hypertensive parents (EH+) and 30 matched offspring of normotensive families (EH-), were studied.

METHODS

All subjects underwent office and 24-h ambulatory blood pressure monitoring (ABPM), conventional and Tissue Doppler Echocardiography (TDE), including assessment of myocardial performance index (MPI).

RESULTS

EH+ showed an increase in office BP with statistical significance in diastolic BP (84 ± 7 vs 73 ± 6 mmHg; p < 0.05). Relative wall thickness (RWT) was greater in EH+ (0.37 ± 0.05 vs 0.31 ± 0.03; p < 0.05) and significantly related to the EH+ condition at the univariate analysis (p < 0.003), whilst the LV mass index was unchanged (84.3 ± 14 vs 80 ± 17 g/m²; p = NS), suggesting a trend towards concentric remodeling. Systolic and diastolic function, in both ventricles, were superimposable in the two groups. The MPI was higher in EH+ (0.49 ± 0.10 vs 0.45 ± 0.08; p = NS) and significantly correlated to RWT (r = 0.47, p < 0.01). However, at the stepwise multiple regression analysis, only the condition of EH + was independently associated with RWT (p <0.006). RWT, according to ROC curves analysis, predicted the condition of EH+ (cutoff 0.359, specificity 89%, sensitivity 82%).

CONCLUSION

Current results provide information about LV myocardial performance in EH+ subjects, related to a LV concentric remodeling and to endothelial dysfunction.

Heart rate as a risk factor for cardiovascular disease

Almost all the epidemiological studies that aimed to answer the question of the relationship between heart rate and all-cause or cardiovascular morbidity and mortality reported that a high heart rate was associated with a higher risk of all-cause mortality and cardiovascular events. This relationship has been found to be generally stronger in men than among women. The increase in the cardiovascular risk, associated with the acceleration of heart rate, was comparable to the increase in risk observed with high blood pressure. It has been shown that an increase in heart rate by 10 beats per minute was associated with an increase in the risk of cardiac death by at least 20%, and this increase in the risk is similar to the one observed with an increase in systolic blood pressure by 10 mm Hg. It has also been shown that heart rate recorded in elderly men has a strong predictive value in survival to a very old age. Taken together, these results indicate that the risk associated with accelerated heart rate is not only statistical significant but also clinically relevant and that it should be taken into account in the evaluation of the patients. Although the association between elevated heart rate and cardiovascular morbidity and mortality has been demonstrated in a large number of epidemiological studies, tachycardia has remained a neglected cardiovascular risk factor until very recently. For the first time, the recent guidelines of the European Society of Cardiology and the European Society of Hypertension indicate than an accelerated heart rate is considered as an independent risk factor and potentially as a target for pharmacologic therapies, especially in high-risk patients.

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.

From hypertension to heart failure: role of nitric oxide-mediated endothelial dysfunction and emerging insights from myocardial contrast echocardiography

There is growing evidence that nitric oxide (NO)-mediated endothelial dysfunction occurs in hypertension and may represent the earliest stage of target organ damage, which ultimately leads to hypertensive heart disease and heart failure (HF). An understanding of how impaired myocardial microvascular function and flow reserve relate to early remodeling during the transition to HF in patients with hypertension may lead to new therapeutic insights. The hypertrophied heart, which is a feature of the adverse structural remodeling in hypertensive heart disease, may be accompanied by impaired coronary flow reserve (CFR). Reduced CFR could potentially cause subendocardial ischemia during conditions of high metabolic demand, such as uncontrolled hypertension and tachycardia. Such vulnerability of the subendocardium to abnormal perfusion or ischemia may accelerate the progression from compensated hypertrophy to HF. In this review, we discuss preliminary evidence that altered NO balance may contribute to cardiac hypertrophy-mediated myocardial ischemia. We also describe early results with myocardial contrast echocardiography in the postulated transition from compensated hypertrophy to cardiac failure. These data support further evaluation of NO mediators as potential targets for novel therapies in hypertensive heart disease.

The effects of exercise on haemodynamic function in relation to the familial hypertension risk model

Offspring hypertensives are characterized by a hyperactive sympathetic nervous system and other early cardiovascular abnormalities that increase the risk of developing hypertension. A physically active lifestyle is associated with a lower risk of hypertension, although the mechanisms are incompletely understood and likely to be multifactorial. One aspect that has received little attention is the interaction of exercise with familial hypertension risk. The present review examines the effects of exercise on haemodynamic function in relation to the familial hypertension risk model. Paradoxically, exercise may be viewed as potent stressor to the cardiovascular system, although recent studies are beginning to show that cardiovascular adaptations, primarily mediated by changes in sympatho-vagal balance, following both acute and chronic exercise may be particularly important for individuals with familial risk of hypertension. Future studies that focus on inflammatory, metabolic, and genetic pathways may uncover further beneficial effects of exercise in relation to familial risk.

Differential protein expression in hypertrophic heart with and without hypertension in spontaneously hypertensive rats

Although cardiac hypertrophy in hypertension has been well recognized, the molecular mechanisms for the development of hypertrophy are still largely unknown. In this study, the protein expression profiles of left ventricular myocardia in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats at different ages were analyzed using 2-DE in combination with MALDI-TOF/TOF MS/MS. The results showed that 20 proteins were modulated in the hypertrophic myocardium. Out of these modulated proteins, 13 proteins presented significant changes in SHR at an early stage prior to the development of sustained hypertension, while the changes of the other 7 protein expressions occurred only at a late stage in SHR when the blood pressure was significantly elevated, and were largely reversible by treatment with rennin-angiotensin-aldosterone system inhibitors losartan or enalapril. These data demonstrate that the changes in energy metabolism in the hypertrophied heart favor an increase in glycolysis and a decrease in oxidation of fatty acid and glucose, which occur at an early stage in SHR without hypertension. Our results also provide evidence to support the hypothesis that oxidative stress plays an important role in the development of hypertensive cardiac hypertrophy.

Impact of Increased Heart Rate on Clinical Outcomes in Hypertension

Thirty-eight studies have been published to date on the association between elevated heart rate and mortality. After adjustment for other risk factors, only two studies for all-cause mortality and four studies for cardiovascular mortality reported an absence of association between heart rate and mortality in male populations. This relationship has been found to be generally weaker among females. Most of these studies investigated samples of general populations. The four studies performed in hypertensive men found a positive association between heart rate and all-cause mortality (hazard ratios ranging from 1.9 to 2.0) or cardiovascular mortality (hazard ratios ranging from 1.3 to 1.7). In spite of this evidence, elevated heart rate remains a neglected cardiovascular risk factor in both genders. The pathogenetic mechanisms connecting high heart rate, hypertension, atherosclerosis and cardiovascular events have also been explicated in many studies. Elevated heart rate is due to an increased sympathetic and decreased parasympathetic tone. This altered balance of the autonomic nervous system tone could explain the increase in events with the increased heart rate. However, it has also been proved that blood flow changes associated with high heart rate favour both the formation of the atherosclerotic lesion and the occurrence of the cardiovascular event. Reduction of heart rate in hypertensive patients with increased heart rate could be an additional goal of antihypertensive therapy. Several trials retrospectively showed the beneficial effect of cardiac-slowing drugs, such as beta-adrenoceptor antagonists (beta-blockers) and non-dihydropyridine calcium channel antagonists, on mortality, notably in patients with coronary heart disease, but no published data are available in patients with hypertension free of coronary heart disease. Other antihypertensive drugs that have been shown to reduce the heart rate are centrally acting drugs and angiotensin II receptor antagonists, but their bradycardic effect is rather weak. The f-channel antagonist ivabradine is a selective heart rate-lowering agent with no effect on blood pressure. Although it has not been proven in existing trials, it would seem reasonable to recommend antihypertensive agents that decrease the heart rate in hypertensive patients with a heart rate higher than 80-85 beats per minute. Since the fast heart rate per se causes cardiovascular damage, all drugs that lower the heart rate have the potential of further reducing cardiovascular events in patients with elevated heart rate. Unfortunately, lowering of the heart rate is not a clinically recognised goal. Prospective trials investigating whether treatment of high heart rate can prevent cardiovascular events, notably in hypertensive patients, are warranted.

High circulating levels of endogenous ouabain in the offspring of hypertensive and normotensive individuals

OBJECTIVE

Impaired diastolic function and left ventricular hypertrophy can occur early in the natural history of essential hypertension. High circulating levels of endogenous ouabain (EO) have been described in essential hypertension and have also been associated with left ventricular hypertrophy. The aim of this study was to investigate whether these cardiac modifications are related to plasma EO levels in the offspring of hypertensive families.

METHODS

The study involved 41 subjects with (FAM+) and 45 subjects without (FAM-) a family history of hypertension. Arterial blood pressure, left ventricular geometry and function, and plasma EO levels were measured in each subject.

RESULTS

Plasma EO levels were higher in the FAM+ subjects (221.5 +/- 10.95 versus 179.6 +/- 9.58 pmol/l, P = 0.004), and directly correlated with both systolic (r = 0.417, P < 0.0001) and diastolic blood pressure (r = 0.333, P = 0.002). Plasma EO was inversely related to an index of cardiac diastolic function determined as the ratio between the early and late peak flow velocity (r = -0.286, P = 0.012) and isovolumetric relaxation time (IVRT) (r = 0.32, P = 0.003). The IVRT was also significantly higher in FAM+, correlated with the IVRT (r = 0.32, P = 0.003). The IVRT was also significantly higher in FAM+, whereas the other echocardiographic parameters were similar to FAM-.

CONCLUSIONS

Among the offspring of families with a positive history of hypertension, circulating EO levels and blood pressure are increased. Plasma EO levels are related to alterations of some indexes of diastolic heart function in these individuals.

Exercise blood pressure, cardiac structure, and diastolic function in young normotensive patients with polycystic kidney disease: a prehypertensive state

BACKGROUND

Increased left ventricular mass (LVM) and left ventricular hypertrophy have been found in early stages of autosomal dominant polycystic kidney disease (ADPKD). The mechanisms that lead to an increase in LVM in this population are unknown. The aim of this study is to evaluate blood pressure (BP) response to exercise and very early alterations in cardiac structure and diastolic function in young normotensive patients with ADPKD.

METHODS

Color Doppler echocardiography and exercise treadmill testing according to the Bruce protocol were performed in 18 young normotensive patients with ADPKD and 18 healthy subjects.

RESULTS

LVM index was greater and isovolumic relaxation time (IVRT) was longer in patients with ADPKD than controls (93.3 +/- 21.4 versus 77.5 +/- 18.6 g/m2; P = 0.02; 100 +/- 20.2 versus 80 +/- 9.7 milliseconds; P = 0.001, respectively). Exercise capacity in metabolic equivalents was similar in both groups. Systolic BP response during exercise and recovery were similar in both groups. Diastolic BP decreased during exercise, but the magnitude of decrease was lower in patients with ADPKD than controls (P = 0.01). During recovery, patients with ADPKD showed a greater sustained diastolic BP than controls (P = 0.02). Patients with ADPKD with an exaggerated systolic BP response had a greater LVM index than those with a normal response (112.1 +/- 10.4 versus 84 +/- 19.2 g/m2; P = 0.001). Multivariate regression analysis showed that exercise systolic BP and diastolic BP were independent predictors of LVM index and IVRT, respectively.

CONCLUSION

Young normotensive patients with ADPKD showed increased LVM index and prolonged IVRT, which are related to exercise BP response. Exaggerated diastolic BP response during exercise suggests an impaired capacity for exercise-induced vasodilatation and may indicate a greater risk for the development of future hypertension.

Diastolic heart failure: The forgotten manifestation of hypertensive heart disease

Heart failure (HF) is a progressively debilitating disorder characterized by frequent hospital admissions and high annual mortality rates. Coronary artery disease (CAD), hypertension, and aging are major risk factors for the development/progression of HF. For years, most of the attention has been focused on HF caused by reduced left ventricular (LV) systolic function, largely attributable to CAD. It is now generally accepted that nearly 50% of elderly patients with HF might have normal or preserved LV systolic function. This condition is commonly referred to as a distinct type of HF caused by LV diastolic dysfunction, and it often accompanies hypertensive heart disease. Isolated diastolic HF is increasingly recognized as the dominant cause of symptoms and hospitalizations from HF in a large proportion of individuals aged 65 and older. However, the clinicians caring for patients with diastolic HF do not fully understand its cause, how it progresses, or how it could be appropriately diagnosed and treated. Because varying degrees of systolic and diastolic dysfunction might coexist in any individual patient, and given the limitation of current diagnostic tools, the overall impact of isolated diastolic HF continues to evolve. Ongoing clinical trials are testing new strategies for treatment of diastolic HF.

Metabolic effects of combined antihypertensive treatment in patients with essential hypertension

Single-drug treatment of essential hypertension (HT) is often insufficient to normalize blood pressure (BP), and high doses of antihypertensive agents can have adverse effects on glucose tolerance (GT) and insulin sensitivity. This study tested whether aggressive BP lowering with combination treatment had any influence on GT or insulin action. In all, 29 nonobese (body mass index [BMI], <30 kg/m ), normolipidemic patients with established HT (159 +/- 3/99 +/- 1 mm Hg) but normal GT were recruited. Eleven normotensive (125 +/- 3/85 +/- 1 mm Hg) subjects were matched to the patients for both anthropometric and metabolic variables. Following baseline studies (serum lipid profile, oral GT, insulin release, and insulin sensitivity assessed by the insulin clamp technique), patients were randomized in a double-blind fashion to two combination regimens (verapamil 180 mg/day + trandolapril 2 mg/day or atenolol 50 mg/day + nifedipine 20 mg/day) and restudied 3 months later. Blood pressure was normalized in both groups (with decrements of 25 +/- 5/17 +/- 2 and 29 +/- 3/15 +/- 2 mm Hg, respectively). Lipid profile, GT, insulin release, and insulin sensitivity of both glucose uptake and lipolysis were unchanged following both treatments. The authors conclude that in nonobese, normolipidemic, glucose-tolerant hypertensive patients, BP normalization with combination therapy is feasible at no cost in terms of undesired effects on glucose and lipid metabolism and insulin sensitivity.

Relation of age to left ventricular function and systemic hemodynamics in uncomplicated mild hypertension

Previous studies in normotensive subjects have shown a slight decline in resting left ventricular pump function and midwall contractility with aging. We examined the relations of age to these variables and to peripheral resistance and vascular stiffness in 272 asymptomatic, unmedicated adults (25 to 80 years old) who had uncomplicated essential hypertension. Cardiac and carotid ultrasound and carotid pressure waveforms were obtained to measure left ventricular dimensions, endocardial and midwall left ventricular shortening, stroke index and cardiac index, end-systolic stress, and pulse pressure/stroke index and beta, pressure-dependent and independent measures of vascular stiffness, respectively. Endocardial and midwall stress-corrected left ventricular shortening assessed ventricular performance. Cardiac index and TPRI did not change with age in either gender, with age-related increases in systolic pressure offset by increasingly concentric ventricular geometry in women and enhanced ventricular systolic function in men. In contrast to the lack of age-related change in traditional hemodynamic indexes, pulse pressure/stroke volume and beta strongly increased with age (P<0.001). Thus, in uncomplicated, relatively mild essential hypertension, neither cardiac index nor peripheral resistance is associated with age. This hemodynamic stability is associated with age-related increased concentricity of ventricular geometry in women and increased ventricular performance indexes in hypertensive men. Vascular stiffness progressively increases with age, independent of change in mean pressure or resistance, possibly contributing to increased rates of cardiovascular events in older individuals.

Influence of gender and family history of hypertension on autonomic control of heart rate, diastolic function and brain natriuretic peptide

OBJECTIVE

To verify in a unitary view whether autonomic control of heart rate and cardiac structure and function are modified early in offspring of hypertensive families.

METHODS AND RESULTS

We selected 87 age- and sex-matched young normotensive subjects with (n = 45) and without (n = 42) a family history of hypertension who underwent evaluations of arterial pressure, time-domain parameters of autonomic heart rate control (24-h ECG monitoring), spectral baroreflex sensitivity, left ventricular geometry and function (echo-Doppler) and plasma brain natriuretic peptide levels (BNP). The group with a family history of hypertension significantly differed from their counterparts for systolic pressure (119 +/- 11 versus 114 +/- 9 mmHg, P< 0.05), heart rate (RR interval, 766 +/- 64 versus 810 +/- 93 ms, P< 0.05), heart rate variability [the standard deviation of normal RR intervals (SDNN), 147 +/- 29 versus 171 +/- 33 ms, P < 0.051, diastolic function (isovolumetric relaxation time, 65 +/- 9 versus 60 +/- 8 ms, P< 0.05) and BNP (23 +/- 13 versus 37 +/- 10 pg/ml, P< 0.05). Baroreflex sensitivity values did not differ between the two groups. When gender was considered, all the above-mentioned measures, as well as baroreflex sensitivity, were significantly different between males with and without a family history of hypertension but not between females, except for BNP, which was lower in males and females with a history of hypertension (males, 24 +/- 11 versus 38 +/- 8 pg/ml, P< 0.01; females 21 +/- 14 versus 36 +/- 13 pg/ml, P < 0.05).

CONCLUSIONS

Male, but not female, hypertensive offspring have modified diastolic function and autonomic control of heart rate; BNP is the only parameter able to characterize hypertensive offspring independently from the influence of gender. This provides the hypothesis that the impaired production of this hormone could play a primary role in the pre-hypertensive state.

An independent relationship between plasma leptin and heart rate in untreated patients with essential hypertension

OBJECTIVE

To test the hypothesis that hemodynamic measurements in patients with essential hypertension are related independently to plasma leptin levels.

PATIENTS AND METHODS

We measured plasma leptin, insulin, office and ambulatory blood pressure and heart rate in 60 men with untreated mild hypertension.

RESULTS

Plasma leptin correlated significantly with body mass index (r = 0.43, P = 0.001), 24 h heart rate (r = 0.35, P = 0.006) and 24 h diastolic blood pressure (r = 0.27, P = 0.04) but not with age (r = 0.03; P = 0.85) or 24 h systolic blood pressure (r = -0.08, P = 0.56). Plasma leptin levels adjusted for body mass index correlated significantly with 24 h heart rate (r = 0.36, P = 0.005) but not with 24 h diastolic blood pressure (r = 0.19, P = 0.15). We divided the patient population into tertiles of body mass index-adjusted plasma leptin levels. Age, plasma insulin, blood pressure, smoking status and physical activity habits were similar across the adjusted leptin tertiles. Patients from the third tertile of adjusted plasma leptin distribution (those with leptin levels higher than would be expected on the basis of body mass index) had significantly faster ambulatory heart rates than subjects from both the first and the second tertiles. The difference in heart rate across the three tertiles was most pronounced for the night-time values.

CONCLUSIONS

In patients with essential hypertension, heart rate is faster in those patients with higher plasma leptin levels. This relationship is independent of age, body mass index, insulin levels, blood pressure level, smoking status and physical activity.

Relationship of tachycardia with high blood pressure and metabolic abnormalities: a study with mixture analysis in three populations

Faster resting heart rate has been shown to be associated with a higher risk of developing hypertension and a greater incidence of cardiovascular morbidity and mortality. The aim of this study was to investigate the distribution of heart rate and its relationship with blood pressure and other cardiovascular risk factors in three populations. One European general population (Belgian study), one North American general population (Tecumseh study), and one European hypertensive population (HARVEST trial) were studied. Within each population, mixture analysis was used to investigate whether a mixture of two normal distributions explained the variance in heart rate better than a single distribution. In the men of all populations, mixture analysis identified a larger subpopulation of subjects with normal heart rate and a smaller one with fast heart rate. The subgroups with tachycardia had higher blood pressure and lipid levels than those with normal heart rate. In the populations in which they were measured, fasting insulin and postload glucose were also higher in the men with faster heart rate. A subgroup with tachycardia could also be singled out among the women from Tecumseh, but no relation between heart rate and blood pressure could be found. These findings show that in Western societies, high heart rate pertains to a distinct subgroup of subjects, who are more frequently men and exhibit the characteristic features of the insulin resistance syndrome. Sympathetic overactivity is likely to be the mechanism underlying this clinical condition.