Circadian blood pressure variation: relationship between dipper status and measures of arterial stiffness.
BACKGROUND
Compared with dippers, hypertensive individuals with a nondipping nocturnal blood pressure (BP) profile have more target organ damage and a worse cardiovascular prognosis, potentially mediated through arterial stiffness.


OBJECTIVE
To examine arterial stiffness and dipping in a population of 314 untreated hypertensive individuals, mean age 48 +/- 8 years, 55% men.


METHODS
Dipping was defined as a 10-20% fall in nocturnal BP; extreme dipping as greater than 20%, nondipping as less than 10%, and reverse-dipping as 0% at most fall in nocturnal BP. Aortic pulse wave velocity (PWV) (Complior) and augmentation index (Sphygmocor) were measured.


RESULTS
Groups did not differ by age, gender, 24-h or daytime mean BP, body mass index, smoking, cholesterol, glucose, renin or aldosterone. The relationship between PWV and dipper-status was J-shaped, with extreme-dippers and reverse-dippers having the highest PWV. Nondippers and reverse-dippers had significantly higher age and sex-adjusted PWV compared with dippers. Following multivariate adjustment for age, gender, mean arterial pressure, heart rate and smoking, reverse-dippers had significantly higher PWV than either dippers or nondippers (P = 0.005 and P = 0.006, respectively). Dipper status was not associated with augmentation index.


CONCLUSIONS
A reverse-dipper pattern, corresponding to the 95% percentile of the night: day BP ratio on ambulatory BP monitoring, identifies a population group with increased PWV. This difference could not be explained by the measured risk factors. Reverse-dippers had significantly less day: night variability in heart rate and wider pulse pressures at night than any of the other groups, suggesting altered sympathetic tone at night as a potential mechanism.
Jerrard-Dunne
Paula
P
Department of Pharmacology and Therapeutics, Trinity Centre for Health Sciences, St James's Hospital, Dublin, Ireland. jerrardp@tcd.ie
Mahmud
Azra
A
Feely
John
J
D000328:Adult; D001011:Aorta / Q000502:physiology* / Q000503:physiopathology; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D011674:Pulse; D012016:Reference Values