Cardioselective and nonselective beta-adrenoceptor blocking drugs in hypertension: a comparison of their effect on blood pressure during mental and physical activity

Physiological reactivity to acute mental stress in essential hypertension-a systematic review

Objective

Exaggerated physiological reactions to acute mental stress (AMS) are associated with hypertension (development) and have been proposed to play an important role in mediating the cardiovascular disease risk with hypertension. A variety of studies compared physiological reactivity to AMS between essential hypertensive (HT) and normotensive (NT) individuals. However, a systematic review of studies across stress-reactive physiological systems including intermediate biological risk factors for cardiovascular diseases is lacking.

Methods

We conducted a systematic literature search (PubMed) for original articles and short reports, published in English language in peer-reviewed journals in November and December 2022. We targeted studies comparing the reactivity between essential HT and NT to AMS in terms of cognitive tasks, public speaking tasks, or the combination of both, in at least one of the predefined stress-reactive physiological systems.

Results

We included a total of 58 publications. The majority of studies investigated physiological reactivity to mental stressors of mild or moderate intensity. Whereas HT seem to exhibit increased reactivity in response to mild or moderate AMS only under certain conditions (i.e., in response to mild mental stressors with specific characteristics, in an early hyperkinetic stage of HT, or with respect to certain stress systems), increased physiological reactivity in HT as compared to NT to AMS of strong intensity was observed across all investigated stress-reactive physiological systems.

Conclusion

Overall, this systematic review supports the proposed and expected generalized physiological hyperreactivity to AMS with essential hypertension, in particular to strong mental stress. Moreover, we discuss potential underlying mechanisms and highlight open questions for future research of importance for the comprehensive understanding of the observed hyperreactivity to AMS in essential hypertension.

Cardiovascular and Autonomic Responses after a Single Bout of Resistance Exercise in Men with Untreated Stage 2 Hypertension

The aim of this paper is to assess the integrated responses of ambulatory blood pressure (BP), cardiac autonomic modulation, spontaneous baroreflex sensitivity (BRS), and vascular reactivity after a single bout of resistance exercise (RE) in men with stage 2 hypertension who have never been treated before. Ten hypertensive men were subjected to a RE session of three sets of 20 repetitions and an intensity of 40% of the 1-repetition maximum (RM) test in seven different exercises. For the control (CTR) session, the volunteers were positioned on the exercise machines but did not perform any exercise. Forearm blood flow was measured by venous occlusion plethysmography. We also analyzed the heart rate variability (HRV), ambulatory BP, blood pressure variability (BPV), and BRS. All measurements were performed at different timepoints: baseline, 20 min, 80 min, and 24 h after both RE and CTR sessions. There were no differences in ambulatory BP over the 24 h between the RE and CTR sessions. However, the area under the curve of diastolic BP decreased after the RE session. Heart rate (HR) and cardiac output increased for up to 80 and 20 min after RE, respectively. Similarly, forearm blood flow, conductance, and vascular reactivity increased 20 min after RE (p < 0.05). In contrast, HRV and BRS decreased immediately after exercise and remained lower for 20 min after RE. We conclude that a single bout of RE induced an increase in vascular reactivity and reduced the pressure load by attenuating AUC of DBP in hypertensive individuals who had never been treated with antihypertensive medications.

GHRH-mediated GH release is associated with sympathoactivation and baroreflex resetting: a microneurographic study in healthy humans

Previous research suggested substantial interactions of growth hormone (GH) and sympathetic nervous activity. This cross talk can be presumed both during physiological (e.g., slow-wave sleep) and pathological conditions of GH release. However, microneurographic studies of muscle sympathetic nerve activity (MSNA) and assessment of baroreflex function during acute GH-releasing hormone (GHRH)-mediated GH release were not conducted so far. In a balanced, double-blind crossover design, GHRH or placebo (normal saline) were intravenously administered to 11 healthy male volunteers. MSNA was assessed microneurographically and correlated with blood pressure (BP) and heart rate (HR) at rest before (pre-) and 30-45 (post-I) and 105-120 min (post-II) after respective injections. Additionally, baroreflex function was assessed via graded infusion of vasoactive drugs. GHRH increased GH serum levels as intended. Resting MSNA showed significant net increases of both burst rate and total activity from pre- to post-I and post-II following GHRH injections compared with placebo (ANOVA for treatment and time, burst rate: P = 0.028; total activity: P = 0.045), whereas BP and HR were not altered. ANCOVA revealed that the dependent variable MSNA was not affected by the independent variables mean arterial BP (MAP) or HR (MAP: P = 0.006; HR: P = 0.003). Baroreflex sensitivity at baroreflex challenge was not altered. GHRH-mediated GH release is associated with a significant sympathoactivation at central nervous sites superordinate to the simple baroreflex feedback loop because GH induced a baroreflex resetting without altering baroreflex sensitivity.

Exercise Blood Pressure Guidelines: Time to Re-evaluate What is Normal and Exaggerated?

Blood pressure responses to graded exercise testing can provide important diagnostic and prognostic information. While published guidelines outline what constitutes a "normal" and "abnormal" (i.e., exaggerated) blood pressure response to exercise testing, the widespread use of exaggerated blood pressure responses as a clinical tool is limited due to sparse and inconsistent data. A review of the original sources from these guidelines reveals an overall lack of empirical evidence to support both the normal blood pressure responses and their upper limits. In this current opinion, we critically evaluate the current exercise blood pressure guidelines including (1) the normal blood pressure responses to graded exercise testing; (2) the upper limits of this normal response; (3) the blood pressure criteria for test termination; and (4) the thresholds for exaggerated blood pressure responses. We provide evidence that exercise blood pressure responses vary according to subject characteristics, and subsequently a re-evaluation of what constitutes normal and abnormal responses is necessary to strengthen the clinical utility of this assessment.

Response to mental and physical stress before and during adrenoreceptor blocker and angiotensin-converting enzyme inhibitor treatment in essential hypertension

The effects of mental, static and dynamic stresses on physiologic parameters before and after beta-blocker (n = 24) and angiotensin-converting enzyme inhibitor (n = 29) treatment were examined. Mental stress induced similar elevation in systolic and diastolic blood pressures (BPs) with and without beta-blocker treatment. During angiotensin-converting enzyme inhibitor treatment, the change in systolic BP was significantly greater (p less than 0.05). Heart rate response was attenuated by beta blockers and unchanged by the angiotensin-converting enzyme inhibitor. Skin temperature and galvanic skin resistance significantly decreased (p less than 0.05) with mental stress. Beta blockers did not change the response pattern, whereas the angiotensin-converting enzyme inhibitor attenuated the stress-induced reduction of both skin temperature and galvanic skin response. After handgrip exercise, increases in systolic and diastolic BPs and heart rate were similar before and after beta-blocker treatment, whereas the angiotensin-converting enzyme inhibitor induced small but significantly fewer (p less than 0.05) changes in diastolic BP and heart rate. Treadmill exercise induced similar changes in systolic and diastolic BPs with both treatments compared with no treatment. The angiotensin-converting enzyme inhibitor appears to provide additional protection to that seen with beta blockers during mental and static stressors by blunted changes in skin temperature and galvanic skin resistance.

Cardiovascular reactivity to psychosocial stressors. A review of the effects of beta-blockade

Fifty-nine studies examining the effects of beta-blockers on cardiovascular reactivity to psychosocial stressors are reviewed. Across all classifications of beta-blockers, heart rate reactivity was reduced (p less than 0.0001), while there were no significant changes in either systolic or diastolic blood pressure reactivity. Nonselective beta-blockers were more often associated with a reduction in heart rate reactivity than selective blockers (p less than 0.05). There was no evidence that drug lipophilicity or intrinsic sympathomimetic activity differentially affected blood pressure or heart rate reactivity; nor was there evidence that the reactivity of hypertensive subjects was differentially affected by blockade compared to the reactivity of normotensive subjects. While beta-blockers are effective in reducing resting blood pressure, they are not effective agents in reducing blood pressure reactivity to mild psychosocial stressors.

Impact of dilevalol on haemodynamic changes during emotional stress

The effect of a single dose of 200 mg dilevalol, beta-adrenoceptor blocker with additional vasodilating properties, and 200 mg oxprenolol on haemodynamic changes induced by emotional stress have been compared in 12 male young Caucasian patients with newly diagnosed labile hypertension. No difference was noted in the stress-induced increase of total peripheral resistance (TPR) following administration of the two substances (11% versus 6%). However, dilevalol revealed a vasodilating action by decreasing TPR at rest (from 1004 to 951 dyn.s.cm-5) and diastolic blood pressure (BP) (from 87 to 75 mm Hg) whereas TPR at rest remained unchanged after the intake of oxprenolol.

Beta-blockers and central nervous system side effects

Beta-adrenergic blocking drugs are a widely used, well tolerated and effective treatment for a variety of cardiovascular and noncardiovascular disorders. Over the years, beta-blockers have been associated with an incidence, albeit low, of CNS side effects. The question of interest, however, is whether the incidence is the same for all members of the class or whether other properties, such as hydrophilicity, have a bearing on the incidence of this type of side effect? This article addresses this question. In pharmacokinetic terms the lipophilic beta-blockers have been shown, both in animals and man, to readily cross the blood-brain barrier in contrast to hydrophilic beta-blockers. This is thought to have possible clinical relevance with respect to the relative incidence of CNS side-effects. To clarify the situation every published clinical paper, in which the beta-blockers propranolol (highly lipophilic, nonselective, no intrinsic sympathomimetic activity (ISA)), pindolol (moderately lipophilic, nonselective, moderate ISA), metoprolol (moderately lipophilic, beta 1-selective, no ISA) and atenolol (hydrophilic beta 1-selective, no ISA) were compared, was assessed for information pertaining to CNS side effects. This comprehensive review of the literature has shown, with few exceptions, that the incidence of CNS side effects such as sleep disturbances, dreaming, nightmares and hallucinations following clinically accepted doses of the four beta-blockers under scrutiny is generally low and that effects on short-term memory are minimal or absent. However, within this group of four drugs the incidence of these side effects is lowest with hydrophilic atenolol and generally highest with pindolol and propranolol. Metoprolol occupies an intermediate position. This order is in agreement with the pharmacokinetic observation that the more hydrophilic the molecule, the less is found in the brain tissue of both animals and man, although in the case of pindolol other factors may be important. The clinical relevance of studies involving psychometric testing is not clear.

Disparate hemodynamic and sympathoadrenergic responses to isometric and mental stress in essential hypertension

The hemodynamic and sympathoadrenergic responses during isometric handgrip and mental arithmetic tests were compared in 18 patients with mild essential hypertension. Mean blood pressure increased significantly after both maneuvers (27% during isometric stress and 10.7% during mental stress), but the increase was significantly higher during isometric stress (p less than 0.001). Both stressors increased the heart rate (p less than 0.001) and cardiac output (p less than 0.001). However, the total peripheral resistance behaved differently, for it increased during isometric stress (p less than 0.05) and remained unchanged during mental stress. Both stressors increased the epinephrine levels (p less than 0.005), but only isometric stress increased the norepinephrine levels (p less than 0.001). It is concluded that both stressors increase cardiac output by way of an increase in heart rate, but isometric stress also increases total peripheral resistance and thus causes a greater increase in arterial pressure. Isometric stress activates both the adrenergic and noradrenergic systems, thereby accounting for the exaggerated response in arterial pressure, whereas mental stress stimulates the adrenergic system only.

Effects of chronic atenolol therapy on cardiovascular response to isometric exercise in essential hypertension

Cardiovascular response to 2 min of isometric handgrip exercise at 50% of maximum voluntary contraction was studied echocardiographically in 10 essential hypertensives, before and during treatment with atenolol for a mean of 2 months. The patients responded with increases in heart rate, systolic and diastolic blood pressures, cardiac output and calculated triple product, no changes in stroke volume and total peripheral resistance, and decreases in ejection fraction, mean velocity of circumferential shortening and mean diastolic posterior wall velocity of the left ventricle before treatment. Chronic atenolol therapy attenuated the increases in heart rate, blood pressure and triple product, and the decreases in ejection fraction, mean velocity of circumferential shortening and mean diastolic posterior wall velocity of the left ventricle but resulted in a marked increase in total peripheral resistance. The pressure response and triple product rise in response to isometric handgrip exercise were also decreased. This suggests an obvious advantage to hypertensive patients who may, therefore, be protected from the risk of cardiovascular complications following isometric exercise.

Effects of acute and chronic beta-adrenoceptor blockade on baroreflex sensitivity in humans

To determine whether beta-adrenoceptor blockade lowers blood pressure by potentiating arterial baroreflex sensitivity (BRS), we compared the effect of acute i.v. and chronic oral beta-blockade on the BRS (phenylephrine technique) of 51 subjects with essential hypertension. Subjects were randomly assigned in a double-blind protocol to one of atenolol, metoprolol, pindolol or propranolol. There was an increase in BRS, unrelated to changes in heart rate, after both acute and chronic beta-blockade. This effect was most evident in younger and less hypertensive subjects. Decreases in blood pressure after 5-months' treatment were unrelated to increases in BRS, indicating that the hypotensive action of these drugs is not dependent upon augmented baroreflex control of heart rate. Only propranolol, of the 4 beta-blockers, increased BRS significantly after acute and chronic treatment. The acute effect of propranolol was significantly different from that of i.v. metoprolol (P less than 0.008) but the effect of long-term treatment with propanolol was not significantly different from that of the other 3 beta-blockers. We conclude that the impaired reflex regulation of heart rate can be improved in younger and mild-to-moderate hypertensive patients by beta-adrenoceptor blockade. Further studies, involving larger numbers and perhaps fewer drugs are needed to determine the relative importance of lipophilicity and beta 1- or beta 2-receptor selectivity in mediating the increase in baroreflex sensitivity seen with treatment.

Central nervous system considerations in the use of beta-blockers, angiotensin-converting enzyme inhibitors, and thiazide diuretics in managing essential hypertension

The most common mild side effects occurring with use of beta-blockers, thiazide diuretics, and angiotensin-converting enzyme inhibitors for blood pressure control are central nervous system symptoms, specifically lethargy, sedation, and fatigue. These symptoms affect 5% to 10% of patients taking these drugs. The mechanism by which beta-blockers may induce central nervous system effects is uncertain. Relative lipophilicity as a factor affecting penetrance of the blood-brain barrier has not proved to be a reliable predictor of whether the drug will cause such disturbances. Comparisons of atenolol (hydrophilic) and metoprolol (lipophilic) have shown no differences between these drugs with respect to side effects of the central nervous system. The incidence of central nervous system effects with angiotensin-converting enzyme inhibitors is similar to that for most beta-blockers. The precise role of the angiotensin-converting enzyme in the central nervous system is not well defined. Most thiazide diuretics are not associated with major complications of the central nervous system, although electrolyte imbalance may occasionally lead to complaints of neurologic symptoms. Because the incidence of central nervous system effects with these three classes of drugs is so low, concern for the side effects of the central nervous system is not a prime consideration in the choice of an initial antihypertensive agent.

Factors influencing blood pressure and heart rate variability in hypertensive humans

We examined the influence of baroreceptor reflex sensitivity (the increase in pulse interval in response to a phenylephrine-induced increase in blood pressure), age, blood pressure, and beta-adrenergic receptor blockade on the variability of blood pressure and heart rate in essential hypertension. Fifty-six subjects were studied before treatment; intra-arterial blood pressure was recorded outside the hospital for 24 hours. Variability was defined (from all beats occurring while subjects were awake) as the standard deviation about the average waking value for mean arterial pressure (MAP) or pulse interval. The correlation (r) between baroreceptor reflex sensitivity and blood pressure variability was -0.47 (p less than 0.0002). Baroreceptor reflex sensitivity was the only independent determinant of blood pressure variability on multiple regression analysis. Thirty subjects were restudied after 5 months of beta-adrenergic receptor blockade. Ambulatory blood pressure was lower during treatment, whereas pulse interval, its variability, and baroreceptor reflex sensitivity were higher. Blood pressure variability was unchanged. The variability of MAP was inversely correlated with baroreceptor reflex sensitivity before (r = -0.42, p less than 0.02) and during (r = -0.45, p less than 0.02) treatment, but it was unrelated to the average ambulatory MAP or to the variability of pulse interval either before or during beta-blockade. Sixteen subjects whose average waking ambulatory blood pressure was 140/90 mm Hg or less were not treated. This group of borderline hypertensive subjects had less variable MAP than did the remaining 40 subjects (12.4 +/- 2.3 [SD] vs 14.5 +/- 2.5 mm Hg; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium channel antagonists. Part III: Use and comparative efficacy in hypertension and supraventricular arrhythmias. Minor indications

The major antihypertensive mechanism of calcium antagonists is by decreasing the systemic vascular resistance, modified by the counter-regulatory responses of the baroreflexes and the renin-angiotensin-aldosterone system. In severe hypertension, the concept that calcium overload of the vascular myocyte could precipitate or aggravate peripheral vasoconstriction provides a logical basis for the use of these agents as first choice therapy; nifedipine, especially, has been well tested. As monotherapy for mild to moderate hypertension each of the three first-generation agents compares well with beta-blockers. Calcium antagonists may have a special role in the therapy of certain patient groups (elderly, black) or in those subjects whose life style involves intense physical or mental exertion (hemodynamics better maintained than with beta-blockade) or in patients with early end-organ damage such as left ventricular hypertrophy or renal insufficiency. However, the goal blood pressure may not be reached during monotherapy so that drug combinations may be required. Further indications for these compounds are as follows. Verapamil and diltiazem are frequently used in supraventricular tachycardias including acute and chronic atrial fibrillation. In the arrhythmias of the Wolff-Parkinson-White syndrome, there is the potential danger of provocation of anterograde conduction. Further indications for calcium antagonists, still under evaluation, include congestive heart failure (controversial), hypertrophic cardiomyopathy (verapamil), primary pulmonary hypertension (high doses required), Raynaud's phenomenon (nifedipine and diltiazem effective), peripheral vascular disease (proof not yet documented), cerebral insufficiency and subarachnoid hemorrhage (nimodipine promising), migraine, exertional bronchospasm, renal disease, atherosclerosis (experimental), and primary aldosteronism (nifedipine inhibits aldosterone release). Second-generation agents include dihydropyridines, such as nitrendipine, nicardipine, felodipine, amlodipine, nisoldipine, nimodipine, and isradipine. From these will be selected agents that are longer acting and provide higher vascular selectivity. New preparations of existing agents include slow-release formulations of nifedipine, verapamil, and diltiazem. Minor side effects include those caused by vasodilation (flushing and headaches), constipation (verapamil), and ankle edema. Serious side effects are rare and result from improper use of these agents, as when intravenous verapamil is given to patients with sinus or atrioventricular nodal depression from drugs or disease, or nifedipine to patients with aortic stenosis. The potential of a marked negative inotropic effect is usually offset by afterload reduction, especially in the case of nifedipine. Yet caution is required when calcium antagonists, especially verapamil, are given to patients with myocardial failure unless caused by hypertensive heart disease. Drug interactions of calcium antagonists occur with other cardiovascular agents such as alpha-adrenergic blockers, beta-adrenergic blockers, digoxin, quinidine, and disopyramide.(ABSTRACT TRUNCATED AT 400 WORDS)

Responses to mental stress and physical provocations before and during long term treatment of hypertensive patients with beta-adrenoceptor blockers or hydrochlorothiazide

1 Cardiovascular and sympatho-adrenal responsiveness to mental stress (CWT; a colour word test), orthostatic testing (ORT) and a cold pressor test (CPT) were examined in three groups of hypertensive patients (n = 14-16) before and after 6 months treatment with metoprolol (243 +/- 26 mg daily), propranolol (149 +/- 16 mg daily) or hydrochlorothiazide (50 +/- 8 mg daily) in an open trial design. 2 Treatment reduced outpatient blood pressures in the three groups similarly (from approximately 155/102 to 135/90 mm Hg). During treatment resting blood pressures in the laboratory were clearly reduced by beta-adrenoceptor blockade but not by thiazide treatment. Metoprolol and propranolol caused similar reductions of basal heart rates and plasma glycerol levels, whereas only propranolol reduced cyclic AMP concentrations in plasma. 3 Before treatment CWT and CPT increased systolic and diastolic blood pressures by about 30%. Heart rate increased by about 30 beats min-1 during CWT and 10-15 beats min-1 during CPT and ORT. Small venous plasma adrenaline responses were evoked by all tests, whereas noradrenaline was elevated mainly by CPT and ORT. Dopamine levels did not change. 4 Heart rate responses to all stressors were markedly and similarly reduced, whereas blood pressure responses were essentially unchanged during metoprolol or propranolol treatment. In the thiazide group circulatory responses to CWT were slightly attenuated, whereas responses to ORT and CPT were unchanged. 5 The systolic blood pressure levels were reduced throughout the test session in all three groups, although less so in the hydrochlorothiazide group. Both beta-adrenoceptor antagonists clearly reduced diastolic blood pressure and heart rate levels at rest and during stress, whereas thiazide treatment caused no significant changes in these respects. 6 The rate pressure product, which increased by 80-100% in response to CWT before treatment, was more markedly reduced by beta-adrenoceptor blockade than by thiazide treatment both at rest and during stress. 7 Self ratings (visual analogue scales) of stress and irritation were increased by CWT in a similar fashion before and during treatment in all groups. beta-adrenoceptor blockade was associated with higher subjective ratings of tiredness at rest, but not after CWT. Performance in the CWT increased slightly more in the thiazide group. The physiological responses to CWT were not correlated to the subjective responses.(ABSTRACT TRUNCATED AT 400 WORDS)