[The relation between blood pressure variation and daily physical activity in early morning surge in blood pressure]

Morning rise in blood pressure (morning surge; MS) has been shown to be associated with the occurrence of myocardial ischemic events and stroke. This study aimed to elucidate the incidence and the mechanism of MS in hypertensive patients (HT). We monitored ambulatory blood pressure (BP) and physical activity in 68 untreated HTs using TM2421 (A & D Co. Ltd.) and ACTIVETRACER (GMS Ltd.) for detection of MS. MS was defined as a rise in BP > 50 mmHg (90% tile of 35 normotensives) during early morning (4:00 to 9:00 A.M.) compared with the lowest basal BP at night. MS was seen in 41 patients (52.6%) and was classified into two groups; MS1: BP rose steeply after waking up (27 patients) and MS2: BP started to rise gradually during sleep (14 patients). The mean age of MS1 was significantly higher than that of MS2 (72 vs. 62 years, p < 0.01). BP reached its basal value earlier in MS2 than in MS1 at night though the basal BP values were comparable between the two groups. Mean 24-hour BP and physical activity were similar between the two groups, though significantly higher incidence of cases with a correlation between SBP and activity was seen in MS1. In conclusion, there are two types of MS, the mechanisms of which may differ. MS occurring immediately after waking up was more common in older HTs, and possibly was related to augmented arousal response in BP, while MS beginning gradually during sleep was more common in younger HTs and was characterized by reaching basal BP earlier at night.