Twenty-four-hour blood pressure profile and blood pressure variability in untreated hypertension and during antihypertensive treatment by once-a-day nadolol

First, blood pressure and heart rate variability was studied in 89 normotensive and hypertensive ambulatory subjects with the use of an intra-arterial monitoring device. Short- and long-term variabilities were analyzed by computer. Absolute variabilities (standard deviations) were greatest in patients with hypertension, but relative variabilities (variation coefficients, i.e., standard deviations as percent of means) were slightly lower in the subjects with more severe hypertension. Second, the effect of nadolol on 24-hour blood pressure and heart rate values and on their variability was assessed in seven ambulatory patients with essential hypertension by means of the same intra-arterial device and computer analysis. Two recording sessions were performed (1) without treatment and (2) after 10 days' administration of nadolol once a day (dose range, 80 to 320 mg). Nadolol, given once a day, was shown to reduce blood pressure uniformly throughout the 24-hour period without loss of activity in the hours farthest from administration. The lack of alteration in relative blood pressure variability suggests that nadolol lowers blood pressure without interfering with the mechanisms involved in cardiovascular homeostasis. Reduction in heart rate variability after nadolol suggests less chance of tachycardia episodes in patients with angina and/or arrhythmias receiving nadolol.