Beta adrenergic blockade in the circulatory regulation of hyperkinetic states

Individualized Beta-Blocker Treatment for High Blood Pressure Dictated by Medical Comorbidities: Indications Beyond the 2018 European Society of Cardiology/European Society of Hypertension Guidelines

Several hypertension guidelines have removed beta-blockers from their previous position as first-choice drugs for the treatment of hypertension. However, this downgrading may not be justified by available evidence because beta-blockers lower blood pressure as effectively as other major antihypertensive drugs and have solid documentation in preventing cardiovascular complications. Suspected inconveniences of beta-blockers such as increased risk of depression or erectile dysfunction may have been overemphasized, while patients with chronic obstructive pulmonary disease or peripheral artery disease, that is, conditions in which their use was previously restricted, will benefit from beta-blocker therapy. Besides, evidence that from early to late phases, hypertension is accompanied by activation of the sympathetic nervous system makes beta-blockers pathophysiologically an appropriate treatment in hypertension. Beta-blockers have favorable effects on a variety of clinical conditions that may coexist with hypertension, making their use either as specific treatment or as co-treatment potentially common in clinical practice. Guidelines typically limit recommendations on specific beta-blocker use to cardiac conditions including angina pectoris, postmyocardial infarction, or heart failure, with little or no mention of the additional cardiovascular or noncardiovascular conditions in which these drugs may be needed or preferred. In the present narrative review, we focus on multiple additional diseases and conditions that may occur and affect patients with hypertension, often more frequently than people without hypertension, and that may favor the choice of beta-blocker. Notwithstanding, beta-blockers represent an in-homogenous group of drugs and choosing beta-blockers with documented effect in prevention and treatment of disease is important for first choice in guidelines.

Role of beta-adrenergic receptor blocking agents in hypertensive diseases: personal thoughts as the controversy persists

The long history of the beta-adrenergic receptor blockers for the treatment of hypertension is fraught with many controversies. The first compound had severe untoward effects preventing their use until propranolol was introduced. It was found effective for treatment of angina pectoris since not all patients with hypertension responded to monotherapy with a meaningful reduction of pressure. Nevertheless, the beta-blockers were most effective in: younger patients, especially with hyperkinetic circulation; with co-morbid diseases (e.g. coronary arterial disease with or without prior myocardial infarction); or when used with a diuretic. Subsequently with the advent of meta-analysis to evaluate more generalized experience, controversy resumed with statements made to exclude beta-blockers for initial hypertensive therapy. Support for this argument was gained with reports of patients developing 'dysglycemia' with treatment. However, exclusion of any one therapeutic class for a multifactorial disease such as hypertension seems unrealistic. Meta-analysis confounded this conclusion since inadequate numbers of patients having specific clinical and biological characteristics were included (especially young patients). This is particularly important at this time when third-party reimbursement procedures are particularly relevant and when the primary care physician must deal with the individual patient. The NICE report has introduced specific thinking along these lines. In-and-of itself, its recommendations are reasonable, but current articles continue to suggest that the 'older' beta-blockers should be excluded from national guidelines for initial antihypertensive therapy. Personally, I disagree; and, no doubt, controversy will continue.

Isoproterenol induced cardiovascular hypersensitiviy in nonpheochromocytoma patients with paroxysmal hyperadrenergic symptoms

The objective of this study was to determine whether graded isoproterenol infusion test identifies a specific hypersensitivity response of the LV diastolic relaxation properties in nonpheochromocytoma patients with paroxysmal symptoms of hyperadrenergic surges. We hypothesized that patients with hyperadrenergic surges, not due to pheochromocytoma, have hypersensitivity of cardiac beta-adrenergic receptor responses to exogenous catecholamines, resulting in enhancement of LV relaxation. We assessed the physiological beta 1 and beta 2 receptor responsiveness to graded isoproterenol infusion (0.01, 0.02, 0.03 and 0.04 microgram/kg per min) in 32 patients presented with hyperadrenergic surges not due to pheochromocytoma. Two major observations were made. First, systemic hemodynamic evaluation using 99m Technetium first pass method revealed hyperkinetic state only in 21 patients (20 females and 1 male; aged 31 +/- 9 years); the other 11 patients were without hyperkinetic circulatory state (10 females and 1 male; aged 41 +/- 9 years). At baseline, plasma catecholamines were not significantly different between the two groups. The baseline corrected LV peak filling and ejection rates (cPFR and cPER) were significantly higher in hyperkinetic group (cPFR: 10 +/- 2 vs 8 +/- 2 x 10(-2) Hz/ms, P = 0.03; cPER: 11 +/- 2 vs 8 +/- 1 x 10(-2) Hz/ms, P = 0.002) and their baseline HR was faster (85 +/- 16 vs 70 +/- 9 beats/min, P = 0.006). Second, the cardiac and vascular responses to isoproterenol infusion were compared between these two groups. During the graded isoproterenol infusion, the response of HR, systolic, and diastolic BP were not significantly different between the two groups at all doses of isoproterenol, but cPFR and cPER had a more marked response to the lowest dose of 0.01 mg/kg per min in the hyperkinetic group. Thus, the graded isoproterenol infusion test can differentiate between two groups of nonpheochromocytoma patients presenting with paroxysmal symptoms of hyperadrenergic surges. Only patients with baseline hyperkinetic hemodynamic profile had accentuated cardiac hyperresponsiveness to a low dose of isoproterenol. We concluded that cPFR and cPER is a more sensitive index to assess the response to isoproterenol, because of metabolic determinants affecting the rate of change in LV volume.

Vasodilatory beta-blockers: systemic and regional hemodynamic effects

The systemic and regional hemodynamic alterations in hypertension and of the beta-adrenergic receptor inhibiting agents are reviewed. Hemodynamically, hypertension may be regarded as persistent elevation of arterial pressure associated with increased total peripheral resistance. In early or mild essential hypertension, however, increased total peripheral resistance may not readily be recognized because of the overriding effect of increased cardiac output. Clearly, the hemodynamics of blood pressure control are complex, and the mechanisms of antihypertensive agents must be used appropriately. The early beta-blockers reduced heart rate and cardiac output immediately after intravenous administration without immediately reducing arterial pressure, and calculated total peripheral resistance was increased. With prolonged oral treatment, arterial pressure decreased while maintaining a reduced heart rate and cardiac output. Total peripheral resistance, however, remained elevated. Recent beta-blockers, such as celiprolol, provide an improved physiologic response by instantly reducing arterial pressure and total peripheral resistance without reducing heart rate or cardiac output or expanding intravascular volume.

Recent issues in antihypertensive drug therapy

Results of recent large scale treatment trials have demonstrated that aggressive management of high blood pressure prevents progression of mild hypertension to the accelerated or malignant phase and reduces incidence of stroke, congestive heart failure, and left ventricular hypertrophy. These trials mostly have utilized a diuretic-based, stepped-care approach to drug therapy, however, and have not shown a consistent beneficial effect of treatment on coronary heart mortality. In addition, the results of studies such as MRFIT have raised questions about serious risks of diuretic treatment in selected patients. These concerns have led to increased use of nonpharmacologic approaches to lowering blood pressure in patients with mild hypertension, but most patients ultimately require drug therapy. Alternative agents to diuretics now being employed as monotherapy in mild hypertension include beta-blockers, calcium channel blockers, ACE inhibitors, alpha-blockers, alpha- and beta-blockers, and, to a lesser extent, centrally-acting sympatholytics and peripheral adrenergic antagonists. Rational use of these agents primarily is based on a careful evaluation of concomitant medical conditions (see Table 3), as well as their mode of action, relative side effects, ease of administration, and cost. Age and race recently have been found to be important determinants of antihypertensive response to agents such as diuretics, beta-blockers, calcium channel blockers, and ACE inhibitors (see Table 3) and appreciation of these relative differences may affect drug selection. When these factors are taken into account, an effective and well tolerated regimen can be tailored to the individual patient. It is hoped that aggressive treatment of hypertension in the future will cause a further decline in cardiovascular mortality in the United States.

[Treatment of hyperkinetic heart syndrome with alinidine and propranolol]

A hyperkinetic heart syndrome has been diagnosed in 10 patients by clinical investigation and right-heart catheterization at rest and during exercise. Subsequently, the patients received 3 X 40 mg alinidine, and 2 X 40 mg propranolol and placebo, each for 2 weeks in a double-blind crossover study. Heart rate at rest (P less than 0.05) and during exercise (P less than 0.001) decreased significantly under alinidine and propranolol to the same extent (control, 83/170; alinidine, 68/146; propranolol, 73/139; placebo, 83/162 beats per min). Lower limb flow at rest and after exercise, measured by plethysmography, as well as left-ventricular fractional shortening and mean velocity of circumferential fiber shortening, measured by echocardiography, decreased insignificantly. Sedation and a dry mouth occurred in six patients under alinidine, while fatigue and cold hands and/or feet were reported by five patients under propranolol. Thus, alinidine may be used as an alternative to beta-blocking in the treatment of the hyperkinetic heart syndrome.

Pharmacologic and physiologic considerations of adrenoceptor blockade

The beta-adrenergic receptor blocking drugs have been in use for the treatment of hypertension for almost two decades. Although the mechanism of their antihypertensive action still is not precisely known, they have become an established major class of therapy for the disease. Most agents produce an immediate reduction in heart rate and cardiac output, later followed by a reduction in pressure. The exceptions include: those agents that possess intrinsic sympathomimetic activity and produce little reduction in heart rate and output; and labetalol, an agent that reduces pressure immediately (associated with the cardiac effects) because it possesses alpha- as well as beta-adrenoceptor blocking effects. Just because a beta-blocking drug reduces cardiac output significantly, it does not follow that renal blood flow will decrease; this depends upon the number and affinity of receptors in the renal circulation. Most beta blockers (including labetalol) reduce renal vascular resistance in patients with uncomplicated hypertension. Other actions of this class of adrenoceptor blocking agents are discussed. As we learn more of the physiologic effects of adrenoceptor blocking agents, there is no doubt that we shall gain more insight into the underlying mechanisms of hypertensive diseases as well as their pharmacologic properties.

Achievements in hypertension: a 25 year overview

Only 25 years ago, the field of hypertension was challenged by retrospective clinical data and epidemiologic information suggesting that an elevated arterial pressure is a major risk factor for enhanced cardiovascular morbidity and mortality. Not only was antihypertensive therapy looked on by many as dangerous and fraught with severe and undesirable side effects, but its validity in reversing the course of disease was not yet demonstrated. This review discusses the dramatic new information amassed over the past 25 years that points to the new physiologic and clinical concepts concerning hypertension. It considers impressive new diagnostic techniques and methods designed to identify secondary forms of hypertension and target organ involvement. In summary, it outlines the feasibility of reversing overall (and cardiovascular) morbidity and mortality with an array of antihypertensive agents that provide the therapeutic ability to suppress most pathophysiologic pressor mechanisms of hypertensive disease. The lesson is clear: hypertension provides the greatest available challenge to the new era of preventive cardiology in the 21st century.

Elevated plasma catecholamines in young hypertensive and hyperkinetic patients: effect of pindolol

1 The sympathetic nervous system plays an important role in the regulation of blood pressure. Plasma catecholamine concentrations are considered to be reliable indices of sympatho-neuronal (noradrenaline) and sympatho-adrenal (adrenaline) activity and reactivity in man.

2 Sympathetic and adrenal activity and reactivity in young patients with essential hypertension or hyperkinetic heart syndrome were compared with an appropriate control group matched for age. The groups of hypertensive patients and patients with hyperkinetic heart syndrome could be clearly distinguished from control subjects on the basis of circulating catecholamine levels at rest.

3 A clear-cut increase in circulating noradrenaline and adrenaline was observed in young patients with essential hypertension and hyperkinetic heart syndrome at rest. Clinically, hypertensive patients were characterized by elevated systolic and diastolic blood pressure and increased heart rate, whereas patients with hyperkinetic heart syndrome had increased heart rate and increased systolic blood pressure, whereas diastolic blood pressure was normal. At rest, there was a significant positive correlation between heart rate and circulating catecholamines in both groups of patients. In hypertensives a positive correlation between heart rate and plasma adrenaline concentrations, in patients with hyperkinetic heart syndrome a positive correlation between heart rate and plasma noradrenaline concentrations could be observed. In addition a positive correlation between plasma noradrenaline concentrations and systolic blood pressure in all groups of patients studied, was obtained.

4 Sympatho-neuronal and sympatho-adrenal reactivity during mental stress or physical exercise increased in both groups of patients, mirrored by an increase in blood pressure and heart rate.

5 Pindolol, a potent non-selective β-adrenoceptor blocking drug with intrinsic sympathomimetic activity and minimal membrane stabilizing properties, administered in a single oral dose of 10 mg, diminished the exaggerated sympathetic tone in both groups of patients by attenuating circulating catecholamine levels at rest or during mental stress, but not during physical exercise.

Electrocardiographic characteristics of neurocirculatory asthenia during everyday activities

We describe the electrocardiographic changes during everyday activities recorded by ambulatory electrocardiographic monitoring in 67 patients with neurocirculatory asthenia. The findings were compared with the results of ambulatory monitoring in 33 healthy controls. We observed episodes of sinus tachycardia > 120/min unrelated to effort in 60 of the patients, 35 had frequent episodes of pronounced sinus arrhythmia, 16 showed transient ST depression, and six transient ST elevation. All these changes appeared during the patients' routine activities, without any unusual exertion and frequently at rest. Periods of sinus tachycardia and sinus arrhythmia were recorded from the patients during sleep. Cardiac arrhythmias, especially ventricular premature beats, were also much more common in those with neurocirculatory asthenia than in the control subjects. These findings indicate that ambulatory electrocardiographic monitoring provides important information on the electrocardiographic characteristics of patients with neurocirculatory asthenia and helps to establish this diagnosis in obscure cases.

beta-adrenergic blockade in essential hypertension: reduced renin release despite renal vasoconstriction

The acute effects of small doses of intravenous propranolol on renin release and on circulatory dynamics were studied at the time of renal arteriography in 12 persons with essential hypertension. All of the subjects had a normal peripheral renin response to chronic sodium depletion and all had normal renal function. Seven subjects received a 10-mEq sodium diet. At the time of arteriography, arterial blood pressure, pulse rate, cardiac output, renal blood flow, and arterial and renal venous renin activity were measured before and 6-20 minutes after the intravenous administration of propranolol (9-18 mjg/kg). Average renin secretion rate in the salt-depleted subjects fell from 367 +/- 80 (SEM) U/ml per 100 g/min to 122 +/- 51 U/ml per 100 g (P=0.03) and renal plasma flow fell from 189 to 155 ml/min per 100 g (P = 0.018). We also found that in the salt-loaded subjects, renal plasma flow fell from 213 to 184 ml/min per 100 g (P = 0.025), whereas renin secretion did not change significantly in either group. We conclude that propranolol rapidly blocks renin release despite circulatory changes which ordinarily constitute a stimulus for renin secretion, i.e., renal vasoconstriction and reduced renal blood flow.