Impaired control of heart rate leads to increased blood pressure variability

Blood pressure variability has been studied from 24-h direct arterial pressure recordings in 109 subjects (36 normals and 73 hypertensives). Baroreflex sensitivity was also measured. From the 24-h record a linear relationship was found between systolic pressure and heart period. The slope was related to baroreflex sensitivity (r = 0.66, P less than 0.001). Those with shallow slopes had a high systolic pressure level and greater variability, thus efficient control of heart rate limits blood pressure variability.