1 The antihypertensive activity of the diuretic xipamide has been studied in 18 patients with mild/moderate essential hypertension using the technique of continuous ambulatory intra‐arterial blood pressure recording. Full data from 48 h blood pressure recordings before and after treatment were available from 13 patients. 2 After a mean period of 3 months' treatment with xipamide 20 mg once daily, both systolic and diastolic blood pressure were markedly reduced throughout the whole 24 h day, the reductions of systolic being statistically significant throughout the whole period, and of diastolic for 19 out of the 24 hourly periods measured. There was no postural hypotension seen during treatment and there was a conspicuous lack of side effects. 3 Xipamide would appear to be as effective as many beta‐adrenoceptor blockers but without their side effects and produces a better control of blood pressure throughout the whole day and night.
SUMMARY The reported circadian rhythm of blood pressure variability with a rise in pressure before awakening has been the subject of controversy. Previous studies have suggested that since heart rate continues to fall before awakening while blood pressure is rising these physiological variables are subject to different control mechanisms. To evaluate further the dissociation of heart rate and blood pressure changes in a group of patients with a fixed heart rate, 11 patients who were dependent on ventricular demand pacemakers underwent intra-arterial ambulatory blood pressure monitoring. Nine aged matched control subjects followed the same protocol. Circadian curves plotted from pooled hourly mean data showed that despite a fixed heart rate the circadian pattern persisted, although attenuated, with blood pressure rising several hours before its rapid rise on awakening. Physiological testing showed that despite a fixed heart rate systolic blood pressure rose in response to bicycle exercise, there was a postural fall in the blood pressure on tilting and a modified Valsalva response. There was considerable beat to beat variability resulting presumably from asychronous pacing. Hour to hour changes did not contribute to the differences between the two groups and were not responsible for attenuation of the circadian rhythm. It is concluded that blood pressure and heart rate control mechanisms may be dissociated, particularly in the period before awakening.Intra-arterial ambulatory monitoring has clearly shown the variable nature of the blood pressure, although this has proved difficult to quantify.1 Millar-Craig et a12 reported a circadian rhythm of blood pressure in which the highest peak occurred in the morning falling gradually during the day and a second peak in the early evening falling to a nadir at 0300 hours. After this nadir the blood pressure rises gradually until the time of awakening, when there is a rapid rise related to arousal. Interestingly, the mean heart rate continues to fall until the time of awakening. This dissociation of heart rate and blood pressure has suggested separate regulatory control mechanisms for blood pressure and heart rate. These data have been the subject of controversy,3 which we have sought to resolve by studying patients with a fixed heart rate produced by ventricular pacemakers. In addition, this study provided an opportunity to study blood pressure variability in patients without heart rate variability.
1 The effectiveness of fixed combination tablets of timolol 10 mg, hydrochlorothiazide 25 mg and amiloride 2.5 mg (Moducren® ) once daily in the control of blood pressure has been assessed in fully ambulant hypertensives by the technique of continuous intra-arterial recording. Highly significant blood pressure reduction (P < 0.001) was obtained consistently throughout the whole day, confirming the potency and usefulness of the preparation for those patients who need more than one drug to control their blood pressure. 2 Blood pressure responses to both isometric and dynamic forms of exercise were also significantly lowered by combination therapy. 3 The addition of a diuretic to a ,3-adrenoceptor blocker appears to be an advantage if the aim of treatment in hypertension is 24 h blood pressure control.
1 We have assessed the efficacy of Viskaldix, a combination of pindolol 10 mg and clopamide 5 mg using continuous intra-arterial ambulatory blood pressure monitoring. 2 Fourteen of the sixteen patients entered were studied on no therapy and following a minimum of 6 weeks at a constant dosage of Viskaldix. 3 Viskaldix produced a marked and consistent reduction of the blood pressure over the 24 h. The diurnal variation in the heart rate was decreased. 4 The results were compared with those of a similar study with once-daily pindolol where there was control during the day but not in the early morning when the blood pressures rose rapidly.
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