Aldo Notargiacomo

Effects of regular exercise on blood pressure and left ventricular hypertrophy in African-American men with severe hypertension

BACKGROUND The prevalence of hypertension and its cardiovascular complications is higher in African Americans than in whites. Interventions to control blood pressure in this population are particularly important. Regular exercise lowers blood pressure in patients with mild-to-moderate hypertension, but its effects in patients with severe hypertension have not been studied. We examined the effects of moderately intense exercise on blood pressure and left ventricular hypertrophy in African-American men with severe hypertension. METHODS We randomly assigned 46 men 35 to 76 years of age to exercise plus antihypertensive medication (23 men) or antihypertensive medication alone (23 men). A total of 18 men in the exercise group completed 16 weeks of exercise, and 14 completed 32 weeks of exercise, which was performed three times per week at 60 to 80 percent of the maximal heart rate. RESULTS After 16 weeks, mean (+/- SD) diastolic blood pressure had decreased from 88 +/- 7 to 83 +/- 8 mm Hg in the patients who exercised, whereas it had increased slightly, from 88 +/- 6 to 90 +/- 7 mm Hg, in those who did not exercise (P = 0.002). Diastolic blood pressure remained significantly lower after 32 weeks of exercise, even with substantial reductions in the dose of antihypertensive medication. In addition, the thickness of the interventricular septum (P = 0.03), the left ventricular mass (P = 0.02), and the mass index (P = 0.04) had decreased significantly after 16 weeks in the patients who exercised, whereas there was no significant change in the nonexercisers. CONCLUSIONS Regular exercise reduced blood pressure and left ventricular hypertrophy in African-American men with severe hypertension.

Direct and reflex cardiostimulating effects of hydralazine.

Increased cardiac output and heart rate after administration of hydralazine have been attributed to reflex activation of the cardiac sympathetic nerves secondary to the decrease in arterial pressure. However, some studies suggest that hydralazine has an additional direct cardiostimulatory effect. The present study was designed to investigate this possibility. Mean arterial pressure, percent change in myocardial contractile force using a Walton-Brodle strain gauge and heart rate were measured in eight open chest dogs anesthetized with sodium pentobarbital. After intravenous administration of hydralazine, 20 mg, myocardial contractile force increased on average by 27 percent and heart rate by 7 percent; mean arterial pressure decreased less than 10 percent. The same reduction of mean arterial pressure with sodium nitroprusside resulted in increases of only 10 percent in myocardial contractile force and 2 percent in heart rate. The differences between the drugs were statistically significant for heart rate (P < 0.05) and myocardial contractile force (P < 0.01). After reductions in mean arterial pressure exceeding 10 percent, the increases in heart rate and myocardial contractile force with either hydralazine or sodium nitroprusside were insignificantly different. Direct injection of 0.8 mg of hydralazine into a coronary artery in four dogs consistently increased myocardial contractile force in the area perfused whereas administration of sodium nitroprusside even in large doses exerted no local inotropic activity. The local effect of hydralazine was blocked by intravenous administration of propranolol. These results suggest that the increase in myocardial contractile force and heart rate after administration of hydralazine is the result not only of a reflex response to a decrease in blood pressure, as occurred with sodium nitroprusside, but also of direct beta adrenergic stimulation of myocardium.

Effect of diuretic therapy on ventricular arrhythmias in hypertensive patients with or without left ventricular hypertrophy

Recent studies have suggested that hypertensive patients with ECG evidence of left ventricular hypertrophy (LVH) may have increased risk of sudden death when treated with diuretics. In the present study echocardiography was used as a more sensitive index for the presence of LVH. Thirty-one patients with uncomplicated hypertension underwent 48-hour ambulatory ECG monitoring both before any treatment and after 4 weeks of hydrochlorothiazide, (HCTZ), 100 mg daily. In 18 patients with left ventricular posterior wall thickness (LVPWT) greater than or equal to 13 mm (average = 14.4 +/- 0.2 mm) on echocardiogram, plasma potassium decreased from 4.1 +/- 0.3 to 3.3 +/- 0.4 mEq/L with HCTZ (p less than 0.01). Premature ventricular contractions (PVCs) averaged 5.7 +/- 9.9/hr at baseline and 7.1 +/- 16.6/hr following HCTZ (p = NS). The total number of couplets was 29 before and 13 after HCTZ, while four brief runs of ventricular tachycardia occurred only before treatment. In the remaining 13 patients with LVPWT less than or equal to 12 mm (average = 11.2 +/- 0.1 mm), plasma potassium decreased from 4.1 +/- 0.3 to 3.4 +/- 0.5 mEq/L with HCTZ (p less than 0.01). The average number of PVCs was 4.3 +/- 8.0/hr after HCTZ (p = NS). One couplet and one 3-beat run of ventricular tachycardia occurred before and one 3-beat run of ventricular tachycardia after HCTZ. Although more complex arrhythmias were noted in the LVH group, the differences were not statistically significant. These results indicate that thiazide therapy does not increase ventricular arrhythmias either in patients with or without LVH.

Treatment of severe hypertension with intravenous labetalol

The effectiveness of repeated intravenous injections of labetolol in reducing blood pressure (BP) was evaluated in patients with severe hypertension. The subjects were 10 patients who were 29 to 61 yr old and who had diastolic blood pressure (DBP) of 125 mm Hg or higher. Repeated injections titrated from 20 to 80 mg were given at 15‐min intervals until there was a reduction in DBP of 30 mm Hg or until 300 mg had been administered. The average reduction of BP ranged from 201 ± 5/132 ± 1 to 157 ± 6/108 ± 4 mm Hg (mean ± SEM). Four patients responded with a reduction in DBP of 30 mm Hg or more with total doses of 60 to 220 mg. Of the remaining six who received the full dose, in four there was a 20 to 29 mm Hg reduction in DBP, in one there was a 10 mm Hg fall, and in one there was no reduction. There was a positive correlation between age and response to intravenous labetolol. No severe side effects were encountered. Intravenous labetolol is useful and well tolerated in patients with severe hypertension.

Effects of diuretic therapy and exercise-related arrhythmias in systemic hypertension

The effect of aerobic exercise on cardiac arrhythmias, plasma catecholamines, potassium and magnesium in patients with systemic hypertension was assessed. Twenty patients (age 54 +/- 8 years) with uncomplicated hypertension underwent exercise treadmill testing twice while receiving placebo and twice while receiving hydrochlorothiazide 100 mg daily. Blood samples for electrolytes and catecholamines were obtained at rest, at peak exercise and 10 minutes after exercise. There were no substantial differences comparing the first to the second placebo phase or the first to the second treatment period. As expected, hydrochlorothiazide treatment caused a significant decrease in serum potassium (4.00 +/- 0.44 to 3.32 +/- 0.49 mEq/liter, p less than 0.001). Serum magnesium did not change with treatment. Serum potassium, serum magnesium and plasma catecholamines increased significantly with exercise. No rebound hypokalemia occurred during recovery. Occasional ventricular premature contractions were noted at rest during all phases of the study, with only a slight increase in frequency during exercise. Couplets were noted only rarely. No difference in the frequency or complexity of arrhythmias was noted between placebo and treatment periods. Diuretic therapy or diuretic-induced hypokalemia has no profound effect on cardiac arrhythmias during or after exercise in patients with uncomplicated systemic hypertension.

Effect of Weight-Reducing Diet on the Blood Pressure of Spontaneously Hypertensive Rats

Abstract Spontaneously hypertensive rats were placed on weight-reducing diets either by limiting regular feedings to twice weekly or by providing half the normal ration daily. Significant reductions in body weight and blood pressure were observed at 2, 4, and 6 weeks after beginning the diet. Blood pressure fell despite maintenance of a normal or elevated sodium intake indicating that the reduction was not secondary to decreased sodium intake. Reinstitution of a normal food intake resulted in a return of body weight and blood pressure within 3 weeks.

Initial and long-term effects of Prazosin on sympathetic vasopressor responses in essential hypertension

In 10 untreated hypertensive patients who received an initial dose of 3 to 5 mg prazosin, supine blood pressure (BP) decreased significantly, from an average of 171 +/- 24/96 +/- 10 to 157 +/- 22/90 +/- 10 mm Hg (p less than 0.025). The Valsalva overshoot, response to cold pressor test and digital vasoconstrictor response to a deep breath were not inhibited. However, during 55 degrees passive headup tilt there was a significant decrease in BP. Seven patients received prazosin for a period of 3 months. After long-term therapy BP returned to baseline levels and a dose of prazosin similar to that given initially produced an average decrease in BP from 174 +/- 20/101 +/- 8 to 167 +/- 23/99 +/- 7 mm Hg. Upright tilting no longer resulted in a decrease in BP. The Valsalva overshoot, cold pressor test and digital vasoconstrictor responses remained unchanged. Orthostatic hypotension after the first dose of prazosin without blockade of the other sympathetic reflex responses suggests that the drug has a greater blocking effect on capacitance vessels than on resistance vessels. Prazosin showed a loss of antihypertensive effectiveness during long-term treatment.

Diuretic therapy and exercise in patients with systemic hypertension

Twenty patients with uncomplicated systemic hypertension underwent treadmill testing twice during placebo treatment and twice during hydrochlorothiazide treatment. Data were collected at rest, at peak exercise and 10 min after exercise. Serum potassium, magnesium and plasma catecholamines increased significantly with exercise. There was no rebound hypokalaemia during the recovery period. Occasional ventricular premature complexes were recorded in all phases of the study. However, there was no difference in the frequency or complexity of arrhythmias between the placebo and the treatment periods.

Comparative Antihypertensive Effects of a Diuretic, Reserpine, and Hydralazine in the Spontaneously Hypertensive Rat

Abstract In order to determine which components of a multiple drug mixture of antihypertensive agents were responsible for controlling the hypertension of SHR, the animals received graded doses of each component separately. Almost all of the antihypertensive activity was contained in hydralazine, whereas methyclothiazide or furosemide and reserpine exhibited essentially no antihypertensive activity even in high doses. This response of the SHR to the various antihypertensive agents contrasts with that of the human whose blood pressure responds well to all these drugs including diuretics and reserpine.