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(Hypertension. 2007;49:237.)
© 2007 American Heart Association, Inc.

Letters to the Editor

Chronobiology Predicts Actual and Proxy Outcomes when Dipping Fails

Halberg Chronobiology Center, University of Minnesota, Minneapolis, Minn

Kuniaki Otsuka

Tokyo Women’s Medical University, Medical Center East, Tokyo, Japan

R.B. Singh

Halberg Hospital and Research Institute, Moradabad, India

Chen-Huan Chen

National Yang-Ming University, Taipei Taiwan

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

As a gauge of variability, dipping, based on day-night ratios of blood pressure, is much discussed,¹ with 2194 hits in a search of the literature on the Internet. But, as compared with dipping, a classification based on chronobiological end points (such as the circadian amplitude and phase) interpreted in the light of reference values specified by gender and age offers superior discrimination in our data. Abnormality in the normal range can occur as (1) a (circadian) blood pressure overswing or circadian hyper-amplitude-tension (CHAT) gauged by a circadian amplitude exceeding the upper prediction limit of presumably clinically healthy peers of the same gender, age group, and ethnicity; (2) an excessive pulse pressure gauged by a persisting excessive difference between systolic pressure, when the heart contracts, and diastolic pressure, when the heart relaxes, measured around-the-clock; (3) circadian ecphasia, an odd timing of the daily blood pressure swing in the absence of an oddly timed daily heart rate pattern to rule out effects of work and sleep schedule shifts that may affect the timing of both blood pressure and heart rate rhythms; or (4) too little heart rate jitter, gauged by a reduced around-the-clock standard deviation of heart rate.

In a 6-year prospective study of 297 patients with no initial history of morbid cardiovascular event undergoing 48-hour ambulatory blood pressure monitoring,² a circadian amplitude above the upper 95% prediction limit of clinically healthy peers matched by gender and age had a relative risk of 4.27 (95% CI: 2.43, 7.51; P. . . [Full Text of this Article]

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