Blood pressure and organ damage.

Casual blood pressure measurements can predict the development of cardiovascular morbidity and mortality, but especially in mild hypertension the correlation indices between casual measurements of blood pressure and the subsequent occurrence of complications are low. Casual and office blood pressure measurements, however, provide a very limited and biased assessment of blood pressure as a risk factor since blood pressure is known to change from moment to moment and to be influenced by its very measurement. Considerable advances in our understanding of the factors influencing blood pressure during daily life and in assessing blood pressure variability have been made possible by use of portable equipment for continuous intraarterial recording of blood pressure. Equipment for noninvasive ambulatory blood pressure monitoring is also available; this equipment is more practical than intraarterial equipment, but is associated with some degree of error and several limitations. Data are reported from a recent study conducted by our group in which target organ damage in 108 hypertensive patients was correlated with blood pressure values as measured by a cuff sphygmomanometer and with various indices derived from 24-h intraarterial blood pressure monitoring. The findings indicate that the incidence and severity of organ damage are more closely related to 24-h blood pressure means than to cuff values. They also provide the first unequivocal evidence that target organ damage also relates to blood pressure variability.