Keith Eliasson

Circulatory and sympatho-adrenal responses to stress in borderline and established hypertension.

Responses to mental stress [a colour word test (CWT), orthostatic testing (ORT) and a cold pressor test (CPT) were studied in 33 subjects with essential hypertension (EHT), 16 subjects with borderline hypertension (BHT) and 17 age and sex-matched normotensive controls (NT). Venous plasma noradrenaline (NA) was similar in all groups. CWT induced marked circulatory responses and metabolic activation with minor increases in NA. Circulatory and NA responses to ORT and CPT were similar in all groups. CWT elevated diastolic blood pressure more in BHT and tended to elevate HR more in EHT and BHT than in NT. Plasma adrenaline (ADR) tended to be higher in BHT and increased during all provocations in EHT and BHT but not in NT. Early hypertension appears to be associated with enhanced cardiovascular and sympatho-adrenal reactivity (resembling a hypothalamic defence reaction) which is revealed by mental stress, rather than stimuli such as ORT or CPT. Venous plasma NA has limitations in defining neurogenic alterations in hypertension since it reflects poorly sympathetic activity in the organs responsible for pressor responses to emotional stimuli. Plasma ADR is more valuable in this respect.

A dietary fibre supplement in the treatment of mild hypertension. A randomized, double-blind, placebo-controlled trial

Objective: To study the effects of a dietary fibre supplement given as monotherapy upon blood pressure in mildly hypertensive patients. Design: The investigation was performed as a prospective randomized, double-blind, placebo-controlled trial for 3 months. Setting: Patients attending an outpatient hypertension clinic in a hospital. Patients: Hypertensive patients with a minimum of two diastolic blood pressure (DBP) readings >90mmHg during a 2-week run-in period were included. Of the 65 patients enrolled, 63 were randomized (32 fibre, 31 placebo). Six patients did not complete the trial. Intervention: Patients were treated with either fibre (7 g/day) or matching placebo. Main outcome measure: Based on previous studies, the a priori hypothesis was that dietary fibre supplementation could reduce blood pressure in hypertensive patients. Results: Body weight was significantly reduced in the fibre group. Dietary fibre significantly reduced DBP and fasting serum insulin. However, no correlation between changes in body weight and systolic blood pressure or DBP was found. Conclusion: A dietary fibre supplement can lower DBP in mildly hypertensive patients independent of changes in body weight.

Personal control over work pace−circulatory, neuroendocrine and subjective responses in borderline hypertension

Cardiovascular and neuroendocrine reactivity during arithmetic task performance were studied in 24 patients with borderline hypertension and normotensive controls. Personal control (self-paced versus externally paced performance) resulted in an attenuated blood pressure (BP) response to task performance in normotensives but not in borderline hypertensives. In response to self-paced work, systolic blood blood pressure (SBP) reactivity was significantly greater in borderline hypertensives, but the heart rate (HR) reactivity was similar in borderline hypertensives and normotensives under the different pacing conditions. Task difficulty (pace variation during external pacing) did not differentially affect reactivity in borderline hypertensives and normotensives. Venous plasma noradrenaline and adrenaline were unaffected by task performance. At rest after the task performance plasma noradrenaline was elevated in both normotensives and borderline hypertensives. The latter group also showed a persistent elevation of diastolic blood pressure after task performance, suggesting a prolonged vasoconstrictor response. The present findings indicate that, in terms of circulatory responses, borderline hypertensives may profit less than normotensives from personal control over environmental demands.

Pace variation and control of work pace as related to cardiovascular, neuroendocrine, and subjective responses.

Two studies of paced and self-paced arithmetic performance are reported. Heart rate and blood pressure were recorded and ratings of subjective arousal obtained. In one of the studies, plasma levels of catecholamines and cortisol were determined. Under externally paced experimental conditions pace variation was found to be quantitatively related to changes in systolic and diastolic blood pressure, as well as to ratings of stress and irritation. This was not the case for heart rate or positively evaluated aspects of subjective arousal. Performance was better and ratings of stress and irritation were lower during self-paced than during paced work at a comparable work pace. In one of the studies the diastolic blood pressure increased less when subjects controlled the pace. Plasma catecholamines did not increase significantly during either externally or self-paced work, but adrenaline tended to increase during paced work. Our findings give partial support to the suggestion that personal control may attenuate sympathoadrenal activation and cardiovascular reactivity.

Effect of beta1-selective and nonselective beta blockade on blood pressure relative to physical performance in men with systemic hypertension

Eleven physically active men with systemic hypertension were studied after 5 weeks of treatment with placebo, atenolol or propranolol. A double-blind, crossover randomized design was used. Blood pressure (BP), heart rate (HR), physical performance capacity, rate of perceived exertion and blood lactate concentrations were measured during rest, exercise to exhaustion and postexercise, at 8 and 24 hours after intake of the last dose. Blood pressure at rest and during exercise was similarly decreased with both drugs (8 and 24 hours), and there was no difference between 8 and 24 hours with any of the treatments. Heart rate (8 hours) was decreased similarly by both drugs, but after 24 hours, HR at increased workloads (above 120 watts) was higher with atenolol compared with propranolol. Maximal HR was lower with propranolol than atenolol at both 8 and 24 hours. Maximal exercise loads (8 and 24 hours) were 231 and 232 watts with placebo, 211 and 212 with propranolol and 228 and 227 with atenolol. That is, maximal workload was decreased with propranolol compared with placebo and atenolol at both 8 and 24 hours. No difference was found between placebo and atenolol at either 8 or 24 hours. The rate of perceived exertion values were higher with propranolol than atenolol. Blood lactate concentrations did not differ according to treatments. The results indicate that atenolol, when given in a dose that decreases resting and exercise BP to the same extent as propranolol, limits physical performance less than propranolol.

The influence of long-term ACE inhibitor treatment on circulatory responses to stress in human hypertension☆

The objective of the study was to examine the influence of angiotensin converting enzyme (ACE) inhibition on circulatory responses to standardized stress tests in primary mild to moderate hypertension. Patients (n = 28) received 5 mg ramipril daily or placebo for 6 weeks in a double-blind crossover design, followed by 6 months of open ramipril treatment. Mental stress (a 20-min Stroops color word conflict test) and a cold pressor test were performed at the end of each of the three study periods. Noninvasive blood pressure and heart rate were recorded. Ramipril reduced systolic and diastolic blood pressure levels at rest (from 146+/-3/99+/-3 with placebo to 135+/-4/94+/-3 at 6 weeks, and 136+/-4/91+/-3 mm Hg at 6 months, in the laboratory) and during mental stress. Resting heart rates were unchanged by ramipril. Ramipril reduced systolic blood pressure and heart rate responses during mental stress; diastolic blood pressure responses were unchanged. Ramipril reduced cardiac workload (systolic blood pressure x heart rate) levels and responses. Treatment effects at 6 months were generally greater than at 6 weeks. During the cold pressor test systolic and diastolic blood pressure levels were lowered by ramipril, but responses were unchanged. Heart rate responses, however, were reduced. Thus, ramipril reduced cardiac workload levels and responses also during the cold pressor test. These findings show that ACE inhibitors can reduce cardiac workload during stressful situations. If confirmed, this would seem to offer an advantage in the treatment of hypertension.

Therapeutic and metabolic effects of sotalol

In a single‐blind, randomized study, the cardiovascular and metabolic effects of sotalol, 40 to 160 mg/day, in six patients with mild essential hypertension were compared to those of placebo at rest and during submaximal dynamic exercise. Resting blood pressure was controlled by sotalol but not the pressor response to exercise, despite reduction of tachycardia. The major metabolic finding on sotalol was an approximately 40% decrease in lipid mobilization during exercise. Alterations in muscle lactate concentrations were much like those caused by other β‐blockers. Plasma concentrations of norepinephrine and epinephrine were doubled during exercise on sotalol, epinephrine disposition more so. No effects on serum lipoproteins were observed after 6 wk on sotalol in therapeutic doses. Despite its special electrophysiologic properties, sotalol appears to induce the same cardiovascular and metabolic changes during exercise as do other β‐blockers.