Management of severe hypertension

Long-term hypotensive effect of atenolol (ICI 66.082), a new beta-adrenergic blocking agent

A report is given from an on-going multicenter trial in Sweden, in which 117 hypertensive patients have been treated with a new cardioselective beta-adrenergic blocking agent, atenolol (ICI 66.082, Tenormin) for an average of six months (range 2-21). Statistically significant reductions of BP were observed, recumbent by 29/19 mmHg (p less than 0.0001) and standing by 28/18 mmHg (p less than 0.0001). Few and comparatively mild side-effects were seen.

Severe Hypertension in the Emergency Department Patient

Severely elevated blood pressure is a common clinical problem en-countered in the Emergency Department. It is often difficult for physicians to differentiate between patients who need emergent blood pressure reduction, requiring the use of intravenous agents and in-tensive monitoring, and those for whom careful, slow reduction in BP is more appropriate. The optimal assessment and management of these patients is reviewed here, with an emphasis on clinical strategies that will most efficiently identify those at greatest risk.

Inhibition of tissue angiotensin converting enzyme activity prevents malignant hypertension in TGR(mREN2)27

BACKGROUND

Activation of the renin-angiotensin system has been implicated strongly in the transition from benign to malignant hypertension. However, the concomitant rise in blood pressure might also have a direct effect on the vascular wall by initiating fibrinoid necrosis and myointimal proliferation. Ascertaining the relative importance of these two factors in this process has proved difficult. TGR(mREN2)27 heterozygotes (HanRen2/Edin- -) have previously been shown to develop malignant hypertension spontaneously and exhibit the characteristic features of human malignant hypertension.

OBJECTIVE

Tissue renin-angtiotensin systems have been implicated in the pathogenesis of malignant hypertension. We set out to determine whether inhibition of this system might protect against development of the disease in a rat model.

METHOD

Male TGR(mREN2)27 heterozygotes (n = 24) were given a non-hypotensive dose of the angiotensin converting enzyme inhibitor ramipril (5 microg/kg per day) from 28 to 120 days of age, untreated rats acting as controls (n = 40). The incidences of malignant hypertension were compared. Systolic blood pressure was measured by tail-cuff plethysmography during treatment; tissue and plasma angiotensin converting enzyme levels and renal histological changes were assessed at the end of the treatment period or upon development of malignant hypertension.

RESULTS

Sixty-three per cent of control rats and 4% of angiotensin converting enzyme inhibitor-treated rats had developed malignant hypertension by 120 days despite there having been no significant difference in systolic blood pressure throughout the course of treatment. Angiotensin converting enzyme activities in kidney, heart and resistance vessels, though not that in plasma, were significantly lower in the treated rats. The degree of medial wall thickening did not differ between the two groups whereas evidence of tissue injury (e.g. intimal fibrosis, fibrinoid necrosis and nephron injury) was significantly less common among rats in the angiotensin converting enzyme inhibitor-treated group.

CONCLUSIONS

Tissue angiotensin converting enzyme inhibition at a non-hypotensive dose almost completely prevented mortality from malignant hypertension and significantly reduced tissue injury in this model, implicating angiotensin II rather than high blood pressure as the principal 'vasculotoxic' agent in malignant hypertension.

A double-blind comparison of acebutolol (Sectral) and propranolol (Inderal) in the treatment of hypertension in black Nigerian patients

Acebutolol and propranolol were compared in forty-five Black African patients in a double-blind randomized trial carried out at Ahmadu Bello University Teaching Hospital in Kaduna, Nigeria. After a wash-out period of 6 weeks, including placebo administration for the last 4 of those weeks, twenty-seven patients were given acebutolol once daily and eighteen were given propranolol twice daily for 12 weeks, followed by a tapering-off period of 2 weeks, making a total of 14 weeks on active treatment. The two beta-receptor blocking drugs were effective in controlling hypertension with final daily doses ranging from 160 to 320 mg in the propranolol group and 400 to 800 mg in the acebutolol group. The supine systolic blood pressure responses with acebutolol were statistically significant and better than those elicited by propranolol. Acebutolol produced less (resting) bradycardia than did propranolol; this may be related to acebutolol's intrinsic sympathomimetic activity. The only unpleasant side-effects reported in this study were slight dizziness in two patients treated with propranolol and slight tiredness in one patient treated with acebutolol. No significant abnormal changes were noted in laboratory tests or chest X-rays. Electrocardiography detected supraventricular tachyarrythmia in five patients: this disappeared by the end of the study. Acebutolol was shown to be a safe, effective and reliable antihypertensive drug, at least comparable to and probably slightly better than, propranolol in the treatment of hypertension in Black Nigerians. It has the added advantage of a once-daily dose schedule.

Abnormalities of vascular wall sodium content in dogs with benign and malignant renal hypertension

The water and sodium content of the saphenous vein was measured in 26 dogs with one-kidney, one wrapped hypertension. For comparison, the same measurements were performed on the contralateral saphenous vein which was removed prior to the induction of hypertension. Malignant hypertension characterized by blindness and a rise in plasma renin activity, developed in 10 dogs. The course of hypertension in the remaining 16 dogs was benign. In benign hypertension, the water and sodium content of the saphenous vein was increased. In contrast, the water content of the saphenous vein was unchanged and its sodium content fell in dogs with malignant hypertension. The dogs with malignant hypertension had a greater sodium content of the saphenous vein prior to the induction of hypertension than the dogs with benign hypertension. The findings indicate that the loss of body water and sodium that has been described in malignant hypertension also affects the composition of blood vessels. The sodium content of blood vessels may be a predictor of the dog's response to a hypertension-producing stimulus.

Acute and chronic treatment of severe and malignant hypertension with the oral angiotensin-converting enzyme inhibitor captopril

The patients with severe and 10 with accelerated or malignant hypertension were treated with the angiotensin-converting enzyme inhibitor captopril. Captopril acutely reduced blood pressure in all patients except two who had suppressed plasma renin activity. Four patients with encephalopathy showed immediate improvement after the first dose. Two patients could be withdrawn from nitroprusside infusion upon administration of captopril. Nineteen of 20 patients have remained on captopril for 12-32 months. Blood pressure is controlled in 18 and improved in two. Eleven required addition of diuretic and one addition of clonidine. The maximal antihypertensive effect of captopril with or without diuretics was evident after 3 months of continuous therapy and was associated with elevated plasma renin levels, normal aldosterone excretion and preservation of renal function. Captopril was well-tolerated, but produced occasional rash, loss of taste and proteinuria. We conclude that captopril, alone or in combination with other drugs, is effective in both the acute and long-term management of severe and malignant hypertension.

Clinical evaluation of atenolol in hypertensive patients

Atenolol, a cardioselective beta-adrenergic blocking agent, was given as the sole hypotensive drug for 8-12 weeks to 20 patients with hypertension of varying degrees of severity. Initial systolic blood pressure ranged from 162-238 mm Hg (mean +/- SEM 196 +/- 5.5 mm Hg) and diastolic blood pressure ranged from 105-143 mm Hg (118 +/- 2.5 mm Hg). Three patients had accelerated hypertension, six had cardiomegaly with recent exertional dyspnea and three were diabetics. Atenolol, 100-300 mg once daily, controlled both the supine and standing blood pressure and markedly attenuated the initial hypertensive response to severe exercise. In 17 patients (85%), atenolol therapy reduced blood pressure more than 20/10 mm Hg; however, adequate blood pressure control was not achieved in severe hypertension. A significant hypotensive action developed within 2 weeks of treatment, and control of hypertension was maintained for 2 weeks after sudden interruption of therapy. No patient had postural or postexercise hypotension. The drug appeared to exert its maximum hypotensive effect at the 100-mg dosage. The magnitude of the hypotensive response was related to the initial systolic blood pressure (r = 0.77, p less than 0.01) and the degree of inhibition of exercise tachycardia (r = 0.66, p less than 0.01). The atenolol plasma level and its hypotensive action were not related. Except for impairment of glucose tolerance in diabetic patients, atenolol had minimal side effects.

Nadolol and propranolol in the treatment of hypertension: a double-blind comparison

Nadolol and propranolol were compared in seventy-five hypertensive patients in a double-blind randomized study conducted at Ain-Shams Hospital. After an initial wash-out period of 5 weeks, including 3 weeks of placebo administration, forty-five patients were given nadolol once daily and thirty patients received propranolol four times per day for 12 weeks, followed by a tapering-off period of 2 weeks. Both beta-blocking agents were effective in controlling hypertension with final daily doses ranging from 80 to 320 mg. Of statistical significance, however, were the better responses of supine systolic blood pressure elicited by nadolol. The only adverse reactions that occurred in this series were slight weight gains in two patients treated with nadolol and moderate dizziness in one patient treated with propranolol. Nadolol was proved to be a safe antihypertensive drug, at least comparable to propranolol in efficacy, with the advantages of a once-daily dose and a lack of direct depressant action on the heart.

On the lipid granularity of renomedullary interstitial cells in benign and malignant courses of renal hypertension

The number of lipid droplets of the renal medullary interstitial cells was registered in 40 rats with "two-kidney Goldblatt hypertension" and in 27 sham operated normotensive controls. A strong degranulation in the unclaimed kidneys was always associated with the malignant course of hypertension, characterized by a disturbance in the sodium and water balance. Giving 2 per cent saline in addition to demineralized water as a drinking fluid the decrease in the number of granules was prevented in most of the malignant cases. Significant changes in the granule count were never registered at a benign course of hypertension. Degranulation of the medullary interstitial cells in the unclamped kidneys does not unequivocally represent the loss of medullary antihypertensive function. It seems to be directly determined by the disturbance of sodium and water balance and indirectly by the hypertension.

An approach to the treatment of essential hypertension

The efficacy and side effects of the combined administration of propranolol and phenoxybenzamine were examined in 19 patients with moderate and moderately severe essential hypertension. By titrating the dosage of both drugs against pulse rate and blood pressure response, propranolol was given between 80 and 160 mg. and phenoxybenzamine between 20 and 50 mg. per day in divided doses. There was a substantial reduction in both systolic and diastolic blood pressure in both recumbent and upright positions without orthostatic hypotension. Normal blood pressure (140/90 mm. Hg or less) or near normal (150/100 mm. Hg or less) was attained in 14 of the patients in the recumbent and 17 in the upright position. Pulse rate also decreased significantly, whereas body weight increased but not significantly so. Except for a reduction of ejaculation in three out of six male subjects, no symptomatic side effects were detected, and no changes in the liver or renal function or in blood count were observed. Despite the short duration of therapy, 3 to 10 weeks, this study clearly demonstrates that propranolol and phenoxybenzamine given together in individualized doses are very effective in lowering arterial blood pressure with minimal side effects.

Beta-adrenoreceptor blockade in hypertension

There is good evidence from many sources that beta-adrenoreceptor blockade is an effective form of therapy in mild, moderate and severe hypertension either alone or in combination with other antihypertensive agents. Although a number os such beta blocking compounds are now available, they appear to have a hypotensive effect of approximately equal magnitude. This hypotensive effect is obtained in both the supine and standing positions thus avoiding postural hypotension. The maximum hypotensive effect may take some time to become apparent. Despite considerable work the mode of action remains uncertain, reduction in cardiac output, resetting of baroreceptors, reduction in plasma renin and a central nervous system effect have been suggested but remain unproved. There is evidence to suggest that these compounds can control, to some degree, the surges in blood pressure resulting from either mental or physical stress. A low incidence of serious side effects has been reported by many workers. Only the long-term use of these compounds in comparison with other antihypertensive agents will determine their place in the management of hypertension.

A comparison of the antihypertensive effect of atenolol (ICI 66 082) and propranolol

Propranolol was given to 30 patients with essential hypertension following randomised, double-blind administration of either placebo or a new cardioselective beta-adrenergic receptor antagonist, atenolol (Tenormin, ICI 66 082). Both atenolol and propranolol caused statistically significant reduction of recumbent and erect blood pressure and heart rate. There were no important differences between these variables on comparison of atenolol and propranolol.

Drievoudige Antihypertensive Behandeling

The systemic arterial pressure is determined by 1) the cardiac output, 2) the blood volume, and 3) the total peripheral resistance. A triple antihypertensive therapy is therefore considered which interferes primarily with these three factors using 1) beta adrenergic blocking agents, 2) a low sodium diet and diuretics, and 3) vasodilating antihypertensive drugs. The hae-modynamic changes during this therapy are described. Since cardiac output, resistance and blood volume cannot be determined routinely in all hypertensive patients, a therapeutic regimen is discussed based on the determination of 1) rate, 2) body weight and 3) arterial blood pressure.

A trial of a new adrenergic beta-receptor blocker, ICI 66.082, in the treatment of hypertension

From a survey of 1250 males, 40-60 years of age, 25 mildly to moderately hypertensive patients have been offered treatment with the new beta-blocker ICI 66.082. Before and during the trial, data were obtained on resting BP and pulse rate, BP, pulse rate and ECGs during near maximal exercise, and various ventilatory function tests. In 15 patients, satisfactory BP control was obtained with ICI 66.082 alone, 25-100 mg twice daily. In 5 patients, the addition of hydralazine or a diuretic was necessary for satisfactory response. In 2 patients satisfactory control was not achieved and 3 patients were excluded for various reasons. Although BP and maximal pulse rate fell markedly during exercise, the total work capacity was not significantly reduced. No deleterious effect on ventilatory function was noted.

Changing concepts in the management of hypertension

Experience in a hypertension clinic attended by 591 patients over a 13-year period has shown marked changes in the pattern of use of hypotensive agents. Thiazides have been used throughout the period in almost all cases. Methyldopa was used for most patients for almost a decade. Since 1967 there has been a steady increase in the use of beta adrenergic blocking agents, and these are now used for over 60% of patients attending the clinic. Combination beta adrenergic blocking agents with peripheral vasilodators such as hydrallazine and prazosin have provided a very effective means of controlling the blood pressure in moderate and severe hypertension. Prazosin, a new peripheral vasodilator, has been used in the treatment of 295 patients. In most cases it has been used in combination with a thiazide diuretic and beta adrenergic blocking agent. Open studies have demonstrated that this is an effective hypot .ensive agent. Side effects are few and are counteracted by combination with a beta adrenergic blocking agent. Prazosin and hydrallazine are being compared in double-blind studies.