Participation of endogenous catecholamines in the regulation of left ventricular mass in progeny of hypertensive parents

GENETIC VARIATION IN THE β(2)-ADRENERGIC RECEPTOR: IMPACT ON INTERMEDIATE CARDIOVASCULAR PHENOTYPES

Genetic variation in drug targets (e.g. receptors) can have pronounced effects on clinical responses to endogenous and exogenous agonists. Polymorphisms in the gene encoding the β(2)-adrenergic receptor (β(2)-AR) have been associated with altered expression, down-regulation, and altered cell signaling in vitro. Because β(2)-ARs play a crucial role in the regulation of the cardiovascular system, the functional importance of genetic variation in the β(2)-AR on cardiovascular responses to physiological or pharmacological stimuli has gained widespread attention. The objective of this review is to characterize these intermediate cardiovascular phenotypes and their influence on cardiovascular disease and adrenergic drug responses.Two common single nucleotide polymorphisms, encoded at codon 46 (Gly(16)Arg) and 79 (Gln(27)Glu) of the β(2)-AR gene, have been studied intensively. They have been shown to be associated with altered vasodilator responses to regional and systemic administration of β(2)-agonists, altered cardiovascular responses to sympathoexcitatory maneuvers, and altered myocardial function. Importantly, these intermediate physiological patterns may influence the development of and the outcomes associated with hypertension and other cardiovascular diseases. As recently reported, β(2)-AR gene variation can risk-stratify patients receiving β-blocker therapy and may predict β-blocker efficacy in patients post acute coronary syndrome or in patients with heart failure.Further studies will advance our understanding of the link between β(2)-AR genotypes, intermediate cardiovascular phenotypes, and clinical phenotypes. In the long term, reassessment of the benefits of β-blocker-therapy within genotype groups should be carried out with the ultimate goal to design the optimal therapeutic regimen for the individual patient.

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.

The use of a telematic connection for the follow-up of hypertensive patients improves the cardiovascular prognosis

BACKGROUND

Inadequate blood pressure (BP) control could be due to incorrect management of hypertensives caused by the lack of interaction between general practitioners (GP) and hypertension specialists.

OBJECTIVES

To test the effectiveness on BP and total cardiovascular risk (TCVR) control of an internet-based digital network connecting specialists and GPs.

METHODS

We created a network among the Hypertension Clinic, Federico II University (Naples, Italy), 23 hospital-based hypertension clinics and 60 GPs from the area (CampaniaSalute Network, CS). Randomized GPs enrolled in CS could update online records of patients (n = 1979). As a control, we included 2045 patients referred to the specialist clinics by GPs from outside the network. All patients completed a 2-year follow-up.

RESULTS

CS provided a larger reduction in BP [systolic/diastolic BP (SBP/DBP): 7.3 +/- 0.4/5.4 +/- 0.3 versus 4.1 +/- 0.4/3.1 +/- 0.26 mmHg, CS versus control; P < 0.001 for both] and percentage of patients with BP < 140/90 mmHg (CS versus control: baseline, 33 versus 34%, NS; end of follow-up, 51 versus 47%, chi = 13.371; P < 0.001). A European Society of Hypertension-European Society of Cardiology (ESH/ESC) TCVR score was calculated [from 1 (average) to 5 (very high TCVR)]. The CS group showed a reduction in the mean TCVR score (CS: from 3.5 +/- 0.02 to 3.2 +/- 0, P < 0.01, ANOVA; control group: 3.5 +/- 0.03 to 3.4 +/- 0.03, NS) and, accordingly, fatal and non-fatal major cardiovascular events (MACE) were less frequent (2.9 versus 4.3%; chi = 5.047, P < 0.02). CS predicts fewer MACE in multiple binary regression analysis (beta:-7.27, P < 0.008) reducing the risk for MACE compared to control [odds ratio (OR): 0.838; 95% confidence interval (CI): 0.73-0.96].

CONCLUSION

Our results support the idea that telemedicine can achieve better control of BP and TCVR.

The Glu27 allele of the beta2 adrenergic receptor increases the risk of cardiac hypertrophy in hypertension

OBJECTIVE

Cardiac and vascular remodeling occur in response to hypertension. Genetic background appears to modify the development of target organ damage (TOD). We evaluated the impact on hypertension-associated TOD of a highly polymorphic gene with elevated significance for the regulation of the cardiovascular system, the beta2AR gene.

METHODS

We recruited 775 hypertensives (mean +/- SE: age 53.5 +/- 0.5, from 20 to 84 years; female 32.7%; systolic (SBP)/diastolic (DBP) blood pressure: 159 +/- 1.2/101 +/- 0.6 mmHg) referred to the departmental outpatient clinic and screened them for the Arg16Gly, Gln27Glu, and Ile164Thr variants of beta2AR gene. We performed association analyses on clinical, anamnesis, anthropometrical and biochemical parameters as well as cardiac and vascular ultrasound.

RESULTS

We found that the three polymorphisms did not affect blood pressure levels. Cardiac TOD appeared to be related to the Glu27 variant. In fact, the Glu27 allele associates with a 1.4-fold higher risk of developing cardiac hypertrophy, and directly correlated with larger systolic and diastolic left ventricle internal diameters. Vascular TOD was not affected by the three polymorphisms. Ancillary to our finding we observed that the Glu27 variant is associated with a higher incidence of dyslipidemia.

CONCLUSIONS

Our data indicate that beta2AR gene polymorphisms participate in the determination of cardiac TOD associated with hypertension.

Angiotensin converting enzyme inhibition for cardiac hypertrophy in patients with end-stage renal disease: what is the evidence?

Dialysis patients show a high prevalence of cardiovascular complications among which left ventricular hypertrophy is one of the most frequent and is independently predictive of mortality. A recent study indicates that partial regression of left ventricular hypertrophy improves mortality and reduces cardiovascular events in end-stage renal disease (ESRD) patients, suggesting the importance of targeting therapeutic strategies to reduce cardiac hypertrophy and improve the outcome in these patients. The pathogenesis of left ventricular hypertrophy in ESRD patients is multifactorial and includes hypertension, activation of the renin-angiotensin system, increased sympathetic activity, chronic volume overload, chronic anaemia and hyperparathyroidism. In this paper, we review the available experimental and clinical evidence showing the important contribution of the renin-angiotensin system as well as its interaction with the sympathetic nervous system in the pathogenesis of left ventricular hypertrophy in ESRD patients. Furthermore, we summarize the results of currently available clinical studies that examined the effects of angiotensin-converting enzyme inhibition or angiotensin receptor antagonism on left ventricular hypertrophy in ESRD patients, and review evidences that support the use of angiotensin-converting enzyme inhibitors or angiotensin receptor antagonists in the ESRD population.

Selective reduction of cardiac mass and central blood pressure on low-dose combination perindopril/indapamide in hypertensive subjects

OBJECTIVE

In hypertension, blockade of the renin-angiotensin system reduces left ventricular mass (LVM) independently of brachial systolic (S), diastolic (D), and mean (M) blood pressure (BP). From central to peripheral arteries, MBP and DBP are practically unchanged, whereas SBP and pulse pressure (PP) increase significantly. The objective was to determine whether changes in LVM under drug treatment was preferentially associated with changes in central or brachial SBP and PP.

DESIGN

A substudy of 146 subjects was selected from 469 hypertensive patients submitted to a double-blind randomized trial comparing the combination of perindopril (2 mg; Per) and indapamide (0.625 mg; Ind) with atenolol (50 mg, one tablet per day).

MAIN OUTCOME MEASURES

Before and after 1 year of treatment: LVM (echocardiography) in 146 subjects and, in 52 of them, central (carotid) BP and timing of wave reflections (tonometry).

RESULTS

LVM changes were significantly associated with antihypertensive treatment, with lower LVM with Per/Ind than with atenolol. Changes in SBP and PP, but not in MBP and DBP, were more significantly associated with Per/Ind than with atenolol, with more pronounced effects using central than brachial measurements, and a longer delay in central return of wave reflections under Per/Ind. In the sampling of 52 patients with tonometry, the change in LVM between the two drug regimens was significantly linked to central, but not brachial, PP change.

CONCLUSIONS

This observational study shows a lower LVM under Per/Ind than under atenolol. The greater change in LVM on Per/Ind was linked to central and not brachial blood pressure.

Are all antihypertensive drug classes equal in reducing left ventricular hypertrophy?

Left ventricular hypertrophy (LVH) is a major cardiovascular risk factor for morbidity and mortality. It is caused by arterial hypertension, although various hemodynamic and nonhemodynamic factors contribute to its development. Especially, the renin-angiotensin-aldosterone system is involved in the pathophysiology of LVH. The Treatment of Mild Hypertension study demonstrated that in mild essential hypertension, nonpharmacologic treatment is an effective tool for treating LVH. There are at least three major meta-analyses with several thousand patients examining the ability of antihypertensive drugs on the reversal of LVH. The results of these meta-analyses are very consistent. Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers achieve significantly better results than b-blockers. The most recently published Losartan Intervention For Endpoint reduction in hypertension study confirmed the superiority of angiotensin receptor blockers against b-blockers in a large-scale prospective trial. It also proves for the first time that regression of LVH is associated with better cardiovascular outcome.

The role of the renin-angiotensin system in the development of cardiovascular disease

A direct, continuous, and independent relation between blood pressure and the incidence of various cardiovascular events, such as stroke and myocardial infarction, is now well accepted. The increase in risk can be attributed to structural and functional changes in target organs. Central to many of these pathophysiologic processes is the renin-angiotensin system (RAS), specifically, angiotensin II. Binding of angiotensin II to angiotensin II type-1 (AT(1)) receptors produces acute vasoconstriction, leading to an increase in blood pressure. AT(1) receptor activation also contributes independently to chronic disease pathology by promoting vascular growth and proliferation, and endothelial dysfunction. These negative consequences of angiotensin II are partly counteracted by angiotensin II type-2 (AT(2)) receptor stimulation, which has favorable effects on tissue growth and repair processes. Thus, the use of selective AT(1) receptor antagonists in the treatment of hypertension has a 2-fold rationale: (1) selective AT(1) receptor blockade targets the final common pathway for all major detrimental cardiovascular actions of angiotensin II, and (2) circulating angiotensin II levels (which increase during AT(1) receptor antagonist treatment) will be free to act only at unopposed AT(2) receptors, potentially providing additional end-organ protection. Angiotensin-converting enzyme (ACE) inhibitors interrupt the RAS by preventing the conversion of angiotensin I to angiotensin II. They also increase plasma levels of bradykinin, which possesses vasodilatory and tissue-protective properties. The combination of an AT(1) receptor antagonist with an ACE inhibitor represents an appealing therapeutic strategy, because it should produce more complete blockade of the RAS, while preserving the beneficial effects mediated by AT(2) receptor stimulation and increased bradykinin levels.

Role of the sympathetic nervous system in cardiac remodeling in hypertension

The role of the sympathetic nervous system in the settings of cardiac hypertrophy is postulated on the basis of experimental and clinical evidence. Only recently, the intimate mechanisms underlying hypertrophic responses of cardiac cell have been explored. Recent evidence spots the role of adrenergic receptors in the activation of several intracellular pathways of signaling that lead to nuclear responses of myocardiocyte. The molecular structures involved in these pathways may represent novel targets of future therapeutic interventions for cardiac hypertrophy and vascular remodeling in hypertension.

Effects of antihypertensive agents on the left ventricle: clinical implications

Hypertensive heart disease (HHD) is characterized by left ventricular hypertrophy (LVH), alterations of cardiac function, and coronary flow abnormalities. LVH is an independent cardiovascular risk factor related to cardiovascular complications in patients with hypertension. Therefore, a decrease in left ventricular mass is a therapeutic goal in these patients. The effect of the different antihypertensive agents on LVH regression has been studied in nearly 500 clinical trials. Most studies conclude that there is regression of LVH after significant decrease in blood pressure with most commonly prescribed antihypertensive agents. However, the ability to regress LVH is different between antihypertensive drug classes. ACE inhibitors and calcium channel antagonists are more potent in reducing left ventricular mass than beta-blockers, with diuretics falling in the intermediate group. Recent data suggest that angiotensin AT(1) receptor antagonists reduce left ventricular mass to a similar extent as ACE inibitors or calcium channel antagonists. Although a large number of studies have established that reversal of LVH decreases the occurrence of adverse cardiovascular events in patients with hypertension, the hypothesis that LVH regression is beneficial has not yet been conclusively proven. On the other hand, the time has come to revisit the current management of HHD simply focused on controlling blood pressure and reducing left ventricular mass. In fact, it is necessary to develop new approaches aimed to repair myocardial structure and protect myocardial perfusion and function and, in doing so, to reduce in a more effective manner, adverse risk associated with HHD. The identification of genes involved in both the process of HHD and the response to therapy may be critical for the development of these new approaches. This article will review briefly the available data on the effects of antihypertensive agents on HHD. In addition, the emerging new concepts on the pharmacology of hypertensive myocardial remodeling and the pharmacogenetic basis of the treatment of HHD will be also considered.

Ambulatory blood pressure monitoring and echocardiography--noninvasive techniques for evaluation of the hypertensive patient

Clinic blood pressure measurements have only limited ability to determine which hypertensive patients are at greatest risk of cardiovascular events. Ambulatory blood pressure monitoring allows for noninvasive measurement of blood pressure throughout the 24-hour period. This may help to clarify discrepancies between blood pressure values obtained in and out of the clinic and confirm the presence of white-coat hypertension, broadly defined as an elevated clinic blood pressure but a normal ambulatory blood pressure. Ambulatory blood pressure values have been shown to have a better relationship to cardiovascular morbidity and mortality and end-organ damage than clinic blood pressure values. Further, patients with white-coat hypertension appear to be at greater risk of cardiovascular morbidity and end-organ damage than a normotensive population, although they are at less overall risk than a hypertensive population. Hypertensive heart disease is characterized by diastolic dysfunction, increased left ventricular mass, and coronary flow abnormalities. Left ventricular hypertrophy increases the risk of coronary heart disease, congestive heart failure, stroke, ventricular arrhythmias, and sudden death. A variety of invasive and noninvasive techniques are described herein that measure left ventricular mass, diastolic function, and coronary blood flow abnormalities. Most antihypertensive treatments promote regression of left ventricular hypertrophy and reversal of diastolic dysfunction, which may decrease symptoms of congestive heart failure and improve survival.

Relation among left ventricular mass, insulin resistance, and blood pressure in nonobese subjects

Because left ventricular (LV) mass (LVM) is a powerful predictor of future cardiovascular events, it is important to identify hemodynamic and nonhemodynamic factors that increase LVM. We studied the separate contribution to LVM of daily arterial blood pressure (BP) and insulin resistance in a consecutive series of 29 (mean+/-SD age, 43+/-13 yr) nonobese (body mass index, 24+/-1.8 kg/m2), nondiabetic, glucose-tolerant subjects with untreated borderline or mild hypertension. The insulin sensitivity index (SI) was quantitatively determined from the frequently sampled iv glucose tolerance test. BP was characterized by ambulatory 24-h BP monitoring, and LVM index (LVMI) was determined by two-dimensional directed M-mode echocardiography. LVMI was directly related to 24-h mean BP (r=0.47; P=0.01). LMVI was also significantly related to Si (r=-0.43; P=0.02). In this nonobese group, neither LVMI nor Si was related to body mass index or age. After adjustment for the influence of BP on LVMI, a significant relation remained between LVMI and Si (P < 0.05). We conclude that in nonobese subjects with high normal BP, insulin sensitivity is related to LVM independently of BP and may be an important modulator of LV growth. In addition to a reduction of arterial BP, optimal prevention of LV hypertrophy in hypertensives may require improved insulin sensitivity.

Distinct vasodilation, without reflex neurohormonal activation, induced by barnidipine in hypertensive patients

Barnidipine is a new 1,4-dihydropyridine calcium antagonist with a strong and long-lasting vasodilatory effect. In order to assess the haemodynamic profile of the antihypertensive effect of barnidipine, a randomized, double-blind study of barnidipine vs nitrendipine was performed in 24 patients with mild to moderate essential hypertension. Following an initial 4-week placebo period, patients whose sitting diastolic blood pressure (SiDBP) was between 95 and 114 mm Hg, and whose sitting systolic blood pressure was between 150 and 219 mm Hg, were randomized (2:1 ratio) to receive either barnidipine (10 mg) or nitrendipine (10 mg) once daily, for a 6-week double-blind period. Subsequently, patients with an SiDBP of less than 90 mm Hg continued for a second 6-week period with the same monotherapy, while patients with an SiDBP of 90 mm Hg or above received double the dose of antihypertensive treatment for the next 6 weeks. Two-dimensional M- and B-mode echocardiography with Doppler flowmetry was performed at the end of both the placebo and active treatment phases. Barnidipine and nitrendipine reduced blood pressure by the same degree (barnidipine: from 165 +/- 2/100 +/- 1 to 145 +/- 2/89 +/- 1 mm Hg, p < 0.01; nitrendipine: from 163 +/- 3/100 +/- 2 to 143 +/- 7/90 +/- 3 mm Hg, p < 0.01) as a result of peripheral vasodilation. This was not accompanied by reflex neurohormonal activation. Moreover, only in the group receiving barnidipine was a significant decrease in plasma noradrenaline observed, both when the patients were in the supine position (from 298 +/- 27 to 214 +/- 21 pg/ml, p < 0.05) and when they were upright (from 472 +/- 37 to 348 +/- 38 pg/ml, p < 0.05).

Alpha1-adrenergic receptor subtype mRNAs are differentially regulated by alpha1-adrenergic and other hypertrophic stimuli in cardiac myocytes in culture and in vivo. Repression of alpha1B and alpha1D but induction of alpha1C

The three cloned alpha1-adrenergic receptor (AR) subtypes, alpha1B, alpha1C, and alpha1D, can all couple to the same effector, phospholipase C, and the reason(s) for conservation of multiple subtypes remain uncertain. All three alpha1-ARs are expressed natively in cultured neonatal rat cardiac myocytes, where chronic exposure to the agonist catecholamine norepinephrine (NE) induces hypertrophic growth and gene transcription. We show here, using RNase protection, that the alpha1-AR subtype mRNAs respond in distinctly different ways during prolonged NE exposure (12 72 h). Alpha1B and alpha1D mRNA levels were repressed by NE, whereas alpha1C mRNA was induced. Changes in mRNA levels were mediated by an alpha1-AR, were not explained by altered mRNA stability, and were reflected in receptor proteins by [3H]prazosin binding. alpha1-AR-stimulated phosphoinositide hydrolysis and myocyte growth were not desensitized. Three other hypertrophic agonists in culture, endothelin-1, PGF2alpha, and phorbol 12-myristate 13-acetate, also induced alpha1C mRNA and repressed alpha1B mRNA. In myocytes from hearts with pressure overload hypertrophy, alpha1 mRNA changes were identical to those produced by NE in culture. These results provide the first example of a difference in regulation among alpha1-AR subtypes expressed natively in the same cell. Transcriptional induction of the alpha1C-AR could be a mechanism for sustained growth signaling through this receptor and is a common feature of a hypertrophic phenotype in cardiac myocytes.

Imidazoline receptor agonist drugs: a new approach to the treatment of systemic hypertension

The imidazoline receptors have recently been discovered to be involved in central nervous system control of blood pressure (I-1 receptor) and in neuroprotection for cerebral ischemia (I-2 receptor). A new class of central-acting antihypertensive agents has been developed, the imidazoline receptor agonists (rilmenidine and moxonidine), which control blood pressure effectively without the adverse effects of sedation and mental depression that are usually associated with central-acting antihypertensives. This new generation of central-acting antihypertensive agents are highly selective for the imidazoline receptor, while having a low affinity for alpha 2-adrenergic receptors.

Effects of one-year treatment with rilmenidine on systemic hypertension-induced left ventricular hypertrophy in hypertensive patients

In patients with essential hypertension, left ventricular hypertrophy (LVH) increases the risk for cardiovascular morbidity and mortality. Thus its reversal represents one of the principal end-points of antihypertensive treatment. We assessed the cardiovascular effects of 1-year antihypertensive treatment with rilmenidine (1 or 2 mg/day orally), a new oxazoline with a potent antihypertensive action that acts selectively through imidazoline-preferring receptors. In 11 hypertensive patients (mean age, 49 +/- 2 years) with LVH, we measured systemic hemodynamics, large artery compliance, cardiac anatomy, and endocrine function. Patients underwent M-mode and 2-dimensional echocardiography as well as Doppler and peripheral pulsed Doppler flowmetry, determination of plasma atrial natriuretic factor (ANF) levels and renin activity (PRA), and of 24-hour urinary electrolyte and creatinine excretion in control conditions (systolic/diastolic blood pressure, 148 +/- 3/102 +/- 1 mm Hg), 4 weeks after blood pressure normalization (131 +/- 2/84 +/- 2 mm Hg; p < 0.01), after 1 year of satisfactory antihypertensive treatment (142 +/- 3/90 +/- 1 mm Hg; p < 0.01) and, finally, 1 month after therapy withdrawal (155 +/- 3/106 +/- 2 mm Hg; difference not significant [NS]). One-year of rilmenidine treatment induced an improvement in brachial artery compliance (from 0.92 +/- 0.06 to 1.16 +/- 0.08 cm4/dyne; p < 0.05), which persisted after withdrawal of treatment (1.17 +/- 0.06 cm4/dyne; p < 0.05). LVH was reversed after 1 year of rilmenidine treatment (from 152 +/- 5 to 131 +/- 4 g/m2 body surface area; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of the single and repeated administration of benazepril on systemic and forearm circulation and cardiac function in hypertensive patients

The hemodynamic and cardiac effects of the new angiotensin-converting enzyme inhibitor, benazepril, were studied in 28 hypertensives in a double blind, placebo-controlled, between-patient study. Hemodynamic studies were performed noninvasively by means of M-mode echo (central hemodynamics and left ventricular systolic function), 2-D echo-Doppler (left ventricular diastolic function), and pulsed Doppler flowmetry (forearm circulation). Examinations were done at the end of a placebo run-in period and 3 hours after benazepril administration, both on the first day and after 6 weeks of treatment (10 or 20 mg once daily, according to patient response). In comparison with placebo, benazepril reduced systolic (p = 0.04) and diastolic (p = 0.003) blood pressure, because of a significant reduction in systemic vascular resistance (p = 0.03), while cardiac output was unchanged. Forearm vascular resistance was reduced and brachial artery compliance increased, although not to a statistically significant level (both p = 0.07). Both systolic and diastolic left ventricular function were positively influenced by the afterload reduction: End-systolic stress was reduced by 12% (p = 0.07), as was the late diastolic peak flow velocity (p = 0.02). All hemodynamic changes were evident after acute benazepril administration, and no differences was observed between acute and repeated treatment. We conclude that, similar to other ACE-inhibitors, benazepril reduces blood pressure through a reduction in vascular resistance, while cardiac output and heart rate are unaffected. These hemodynamic effects occur as early as after the first administration and exert a favorable influence on left ventricular dynamics.

Reversal of cardiac and large artery structural abnormalities induced by long-term antihypertensive treatment with trandolapril

In 15 patients with untreated mild to moderate essential hypertension and left ventricular hypertrophy, we assessed blood pressure, echocardiographic left ventricular mass index, brachial artery compliance (pulsed doppler flowmetry), and calculated forearm vascular resistance (strain gauge plethysmography) before, during (6 and 12 months) and after (1 month washout period) 1 year of satisfactory (blood pressure < or = 140/90 mm Hg) antihypertensive therapy with the angiotensin-converting enzyme inhibitor trandolapril (2.0 mg orally once daily). During the antihypertensive effective treatment, we observed a significant reduction of systolic and diastolic blood pressures, left ventricular mass index, and forearm vascular resistance at both 6 and 12 months. In addition, brachial artery compliance was significantly increased. After washout, systolic (156 +/- 3 mm Hg) and diastolic (102 +/- 1 mm Hg) blood pressures returned to levels comparable to baseline. However, left ventricular mass index (132 +/- 4; p < 0.01) and brachial artery compliance (1.53 +/- 0.01; p < 0.01) were still different from baseline. These results demonstrate that chronic antihypertensive treatment with trandolapril is associated with a stable regression of cardiac and vascular abnormalities, which is partially unrelated to the blood pressure lowering effect.

Heredity and hypertension: impact on metabolic characteristics

This study was performed to evaluate the possible role of heredity in the clinical characteristics of hypertension. Metabolic, endocrine, and renal measurements were compared in subjects with normal blood pressure who had a family history of hypertension (n = 60) with those of subjects with normal blood pressure who did not have a family history of hypertension (n = 48). The groups were matched for age (mean, 44 +/- 2 years and 45 +/- 2 years) and blood pressure (127 +/- 1/77 +/- 1 mm Hg and 127 +/- 2/77 +/- 1 mm Hg). The following parameters were higher in the patients with a family history of hypertension than in those without. Plasma insulin concentrations (14.1 +/- 1.1 vs 10.8 +/- 1.0 microU/ml; p less than 0.05), insulin-glucose ratio (0.15 +/- 0.01 vs 0.11 +/- 0.010; p less than 0.05), norepinephrine concentrations (315 +/- 24 pg/ml vs 208 +/- 20 pg/ml; p less than 0.01), plasma renin activity (2.1 +/- 0.2 ng Angl/ml/hr vs 1.6 +/- 0.2 ng Angl/ml/hr; p less than 0.02), total cholesterol levels (217 +/- 8 mg/dl vs 197 +/- 0.3 mg/dl; p less than 0.05), creatinine clearance (125 +/- 9 ml/min vs 96 +/- 8 ml/min; p less than 0.01), and albumin excretion rate (3.2 +/- 0.3 micrograms/min vs 2.6 +/- 0.3 micrograms/min; p = 0.1). Moreover, patients with a family history of hypertension had smaller increases in systolic blood pressure during treadmill exercise (55 +/- 3 mm Hg vs 64 +/- 3 mm Hg; p less than 0.03). There were no differences in echocardiographic left ventricular mass index between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Sympathetic modulation of the cardiac myocyte phenotype: studies with a cell-culture model of myocardial hypertrophy

Myocardial hypertrophy is the common endpoint of many cardiovascular stimuli such as hypertension, myocardial infarction, valvular disease, and congestive failure. Catecholamines have long been implicated in the pathogenesis of myocardial hypertrophy, however, it is very difficult to sort out catecholamine mechanisms in vivo. We have developed a cell-culture model which excludes hemodynamic effects and allows the assignment of receptor specificity to catecholamine effects. Utilizing this system, we have shown that stimulation of the alpha 1 adrenergic receptor leads to the development of myocardial hypertrophy and results in the selective up-regulation of the fetal/neonatal mRNAs encoding skeletal alpha-actin and beta-MHC, a pattern similar to that seen with hypertrophy in-vivo. Utilizing a co-transfection assay, we have also obtained data that suggest that the beta-PKC isozyme is in a pathway regulating transcription of the beta-MHC isogene. Beta adrenergic stimulation of the cultured cardiac myocytes also results in a modest degree of hypertrophy, however, this effect may be dependent upon myocyte contractile activity and may involve, at least in part, the non-muscle cells present in the culture system.

Effects of chronic infusion of norepinephrine on cardiac structure, function, and biochemistry: physiologic versus pathologic hypertrophy

Ventricular hypertrophy should be divided into at least physiologic and patholgic states in order to clarify structural and functional clinical alterations. The elucidation of the structural, functional, and biochemical mechanisms of ventricular hypertrophy is vital to designing effective preventive and therapeutic measures for the hypertensive patient. Tissue markers may help differentiate pathologic from physiologic hypertrophy. Studies have established the concept that norepinephrine may be a myocardial cellular hypertrophying hormone. The studies ranged from the direct application of norepinephrine to isolated myocardial cells to the chronic subhypertensive infusion of norepinephrine into the conscious, free-roaming dog. Norepinephrine infusion can produce physiologic ventricular hypertrophy or a pathologic state of hypertrophic cardiomyopathy, the former by a three- to four-month infusion and the latter by an infusion of more than six months. The biochemical effect of subhypertensive infusion of norepinephrine was studied prior to the production of ventricular hypertrophy, thereby permitting the elucidation of the mechanism of the hypertrophic process. The biochemical stimulus for the production of myocardial cellular hypertrophy is postulated to be a diminution of cyclic AMP and a stimulation of alpha-1 receptors. Because the ventricular septum has the highest content of adenylate cyclase, which does not increase with cyclic AMP, these changes are postulated to be the biochemical basis for septal hypertrophy in the disease entity hypertrophic cardiomyopathy. A unique conscious-canine model for the production of a myocardial infarction capable of creating a controlled localized occlusion of the coronary artery is presented.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of diastolic function after reversal of left ventricular hypertrophy induced by long-term antihypertensive treatment with tertatolol

In 15 previously untreated hypertensive subjects with left ventricular (LV) hypertrophy who responded favorably (supine blood pressure less than or equal to 140/90 mm Hg) to antihypertensive treatment with a nonselective beta-blocking agent, tertatolol, the effects of reversal of LV hypertrophy on systolic and diastolic function were assessed. Patients underwent echocardiographic and radionuclide studies in control conditions (phase 1), after 1 month of blood pressure normalization (phase 2), after reversal of LV hypertrophy or at least a 20% reduction of LV mass compared to basal value (phase 3) and finally, after a 1-month washout (phase 4). In phase 2, blood pressure (130 +/- 2/85 +/- 1 vs 148 +/- 4/104 +/- 1 mm Hg) and heart rate (59 +/- 1 vs 76 +/- 2 beats/min) decreased (both p less than 0.01); LV mass remained unchanged. There were improvements in peak filling rate (end-diastolic volume/s) (2.4 +/- 0.1 vs 2.0 +/- 0.1), ejection fraction (65 +/- 1 vs 61 +/- 1%) and their ratio (stroke counts/s) (3.7 +/- 0.2 vs 3.2 +/- 0.1) (all p less than 0.05). In phase 3, blood pressure and heart rate were unchanged and reversal of LV hypertrophy was accompanied by a further increase in peak filling rate (2.9 +/- 0.1), ejection fraction (69 +/- 1%) and their ratio (4.1 +/- 0.1) compared to phase 2 (all p less than 0.01). Finally, in phase 4 blood pressure and heart rate returned to the basal value, but peak filling rate (2.7 +/- 0.1) and ejection fraction (65 +/- 1%), although reduced compared to phase 3, were still higher than phase 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproducibility of left ventricular mass measurements by two-dimensional and M-mode echocardiography

Both two-dimensional and M-mode echocardiography provide accurate estimates of left ventricular mass. However, their reproducibility in serial studies has not been compared, although this issue is critical to evaluation of regression of hypertrophy. To determine which technique provides more reproducible estimates of left ventricular mass, three serial studies were performed prospectively in each of eight normal adults over 5 months. Both two-dimensional and M-mode echocardiograms were obtained at each of these 24 studies. Measurements were performed by two independent observers who did not know patient identity. For the two-dimensional method, left ventricular mass was determined with use of a computer light-pen system and the truncated ellipsoid formula. For the M-mode method, mass was calculated from Penn convention measurements with use of the cube formula. At study 1 the group mean left ventricular mass by two-dimensional echocardiography (115 +/- 20 g) did not differ from that by M-mode study (127 +/- 37 g, p = NS). However, serial estimates of left ventricular mass were more reproducible by two-dimensional echocardiography. The mean difference among the three serial two-dimensional studies in each individual was 4.8 +/- 4 g (4.2 +/- 3%) by the two-dimensional method, but was 18.5 +/- 13 g (14.9 +/- 10%) by the M-mode method (p = 0.01). Interobserver results for left ventricular mass by two-dimensional echocardiography correlated closely (r = 0.95, n = 24, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Predictors of left ventricular hypertrophy in patients with essential hypertension

The purpose of this study was to assess clinical variables which might be predictive of echocardiographic left ventricular hypertrophy in mildly hypertensive patients. Eighteen patients (mean age 51) were studied following four weeks of hydrochlorothiazide monotherapy. Variables assessed included age, duration of hypertension, body surface area, serum cholesterol, alcohol consumption, smoking, maximum systolic and mean blood pressures, and variability of blood pressure determined from hourly measurements taken 12 hours after hydrochlorothiazide dosing. Using stepwise multiple linear regression (with left ventricular mass index analyzed as a continuous variable), the variability of blood pressure was predictive of an elevated left ventricular mass index (p less than 0.0003, r2 = 0.61). The duration of hypertension added significantly to the variability in predicting an elevated left ventricular mass index (p less than 0.004, multiple r = 0.74). In conclusion, echocardiographic left ventricular hypertrophy was significantly related to the variability of blood pressure recorded hourly for 12 h after subjects received 50 mg of hydrochlorothiazide.

Cardiac function in systemic hypertension before and after reversal of left ventricular hypertrophy

In 3 age- and sex-matched groups of subjects--15 normotensives, 15 hypertensives without left ventricular (LV) hypertrophy and 15 hypertensives with LV hypertrophy--the slopes of the regression line obtained by plotting the individual values of LV fractional shortening against the corresponding values of echocardiographic end-systolic stress were compared. The first 2 groups were studied only in control conditions while the third group was restudied after a 20% reduction in LV mass index induced by a long-term antihypertensive treatment and after a 3-week washout period. A significant relation between fractional shortening and end-systolic stress was found in all instances. The slope of this correlation was higher in normotensives (-0.251) and in hypertensives without LV hypertrophy (-0.232) (both p less than 0.01) than in hypertensives with ventricular hypertrophy (-0.079). In this latter group, the slope increased after the reversal of LV hypertrophy (-0.230, p less than 0.01) and remained unchanged (-0.202) at the end of the washout period. No difference was detectable between the slopes obtained in these patients after reversal of LV hypertrophy, both with the antihypertensive treatment on and off, and those of normotensives and hypertensives without LV hypertrophy. Thus, LV hypertrophy attenuates the influence of changes in afterload on LV function. Reversal of LV hypertrophy restores a fractional shortening end-systolic stress relation quite comparable to that found both in normotensives and in hypertensives before the development of LV hypertrophy.

Reflex control of coronary vascular tone by cardiopulmonary receptors in humans

To examine whether cardiopulmonary receptors participate in the reflex control of coronary vascular resistance, systemic and coronary hemodynamics were assessed before and during -10 mm Hg lower body negative pressure in eight normal subjects and eight hypertensive patients with left ventricular hypertrophy. In both study groups, lower body negative pressure induced a significant decrease in right atrial pressure, left ventricular filling pressure and cardiac output, an increase in systemic vascular resistance and no change in mean arterial pressure and heart rate. In normal subjects, there was also a significant increase in plasma norepinephrine concentration (from 294 +/- 39 to 421 +/- 47 pg/ml, p less than 0.01). This increase was accompanied by a reduction in coronary blood flow, assessed by the continuous thermodilution method (from 101 +/- 5 to 79 +/- 4 ml/min, p less than 0.05). An increase in coronary vascular resistance (from 0.865 +/- 0.1 to 1.107 +/- 0.1 mm Hg/ml per min, p less than 0.05) and in myocardial oxygen consumption was detected in normal subjects during cardiopulmonary baroreceptor unloading. In contrast, in hypertensive patients, -10 mm Hg lower body negative pressure failed to induce any change in plasma norepinephrine, coronary blood flow or vascular resistance. Intravenous propranolol administration caused no significant change in the systemic hemodynamic response to -10 mm Hg lower body negative pressure in either study group, but it did abolish the decrease in coronary flow and the increase in plasma norepinephrine, coronary vascular resistance and myocardial oxygen consumption observed in normal subjects in control conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of chronic antihypertensive treatment with ketanserin versus metoprolol on blood pressure and large arteries' compliance in humans: a cross-over double-blind study

The antihypertensive efficacy of a serotonin-receptor antagonist, ketanserin, was compared with that of a well-established antihypertensive drug, metoprolol, and their cardiac and forearm hemodynamic effects were investigated using echocardiography and bidimensional pulsed Doppler flowmetry, respectively. Twenty hypertensive subjects completed a double-blind, cross-over, randomized study using ketanserin and metoprolol. Two 5-week courses with ketanserin or metoprolol were preceded by a placebo period; the total duration of the study was 15 weeks. Despite a comparable efficacy in reducing systolic and diastolic blood pressure (about 10% of the basal value), the two drugs showed quite different effects on forearm hemodynamics. Ketanserin increased forearm blood flow and induced a significant decrease in forearm vascular resistance (from 141 +/- 16 to 75 +/- 11 mm Hg/mL/sec, P less than .01). Furthermore, this treatment was able to improve brachial artery compliance (from 1.89 +/- .3 to 3.2 +/- .3 cm4/dyne 10(-7), P less than .01). On the contrary, metoprolol did not modify forearm hemodynamics. Both drugs did not significantly modify cardiac performance, as evaluated by left ventricle circumferential fiber shortening. Cardiac output was increased by ketanserin (from 5.9 +/- .3 to 6.6 +/- .5 L/min, P less than .05) and fell during treatment with metoprolol (from 5.9 +/- .4 to 4.9 +/- .3 L/min P less than .01). Thus, the two drugs reduce blood pressure through different hemodynamic mechanisms and the effects of ketanserin on systemic and peripheral circulation seem more favorable.

Beta blockers and left ventricular hypertrophy in hypertension

It is now generally accepted that hypertension-induced left ventricular hypertrophy (LVH) represents a phenomenon of multifactorial origin. Antihypertensive therapy with beta-blocking drugs influences most of the factors involved in the control of left ventricular mass. Therefore, although initial animal experiments yielded conflicting results, it is not surprising that a great deal of evidence has been accumulated in clinical studies showing that successful long-term antihypertensive treatment with beta blockers induces regression of LVH in hypertensive subjects. Differences in molecular structure among various beta-blocking agents do not seem to influence this property. On the contrary, the question of whether reversal of LVH represents a beneficial or harmful byproduct of antihypertensive treatment with beta blockers is still unanswered. Animal and clinical studies suggest that left ventricular systolic function is unchanged or even improved after regression of LVH, whereas the ability of the heart to withstand recurrence of hypertension is slightly reduced. Furthermore, development of LVH in hypertensive subjects is associated with abnormalities in diastolic function which are not reduced by reversal of LVH induced by antihypertensive treatment with beta blockers.

Effects of celiprolol on systemic and forearm circulation in hypertensive patients: a double-blind cross-over study versus metoprolol

The antihypertensive efficacy of a new beta-receptor blocking agent, celiprolol, was compared with that of a well-established antihypertensive drug, metoprolol. Their systemic and forearm hemodynamic effects were investigated using echocardiography and two-dimensional pulsed Doppler flowmetry, respectively. Twenty hypertensive patients completed a double-blind, cross-over, randomized study using celiprolol and metoprolol. Two six-week courses with celiprolol or metoprolol were preceded and followed by a two-week placebo period; the total duration of the study was 18 weeks. In spite of a comparable efficacy in reducing systolic and diastolic blood pressure (about 10% of the basal value), the two drugs showed quite different systemic and regional hemodynamic effects. Celiprolol induced a significant decrease in forearm vascular resistance (from 157 +/- 17 to 113 +/- 13 mm Hg/mL/s, P less than .01) and total peripheral resistance (from 1596 +/- 90 to 1398 +/- 91 dyne.s.cm-5, P less than .05) whereas cardiac output remained unchanged and forearm blood flow increased. Metoprolol reduced cardiac output (from 6.5 +/- 3 to 5.7 +/- 3 L/min, P less than .05), through a reduction in heart rate, since stroke volume was unchanged. Both drugs did not significantly modify cardiac performance, as evaluated by left ventricle fractional shortening and ejection fraction. Thus, the two drugs seem to reduce blood pressure through different hemodynamic mechanisms.