The Mechanism Of Morning Blood Pressure Peak In Essential Hypertension

Objective To explore the factors influencing the morning blood pressure peak in EH. To investigate the effect of morning blood pressure peak on the target organ damage and mechanism of cardiovascular events in EH with morning blood pressure peak.Methods 70 subjects with essential hypertension and 20 healthy subjects were recruited. Noninvasive ABPM was performed with automatic devices from 8:00～9:00 to next early morning 8:00～9:00. Normal daily activities were allowed . Blood pressures and heart rates were analyszed in the morningtime(6:00～10:00),daytime(10:00～22:00)and nighttime(22:00～5:00). The morning BP surge(MS) was defined as a rise in systolic BP ≥50 mm Hg during early morning (6:00 to 10:00 AM) compared with the lowest BP during the night. The morning blood pressure peak (MP) was defined as MS ≥50 mm Hg or mean morning systolic BP (MSBP)≥170 mm Hg. EH subjects with MP were defined as the MP+ group and otherwise as the MP- group. Patients were subclassified according to the percentage of nocturnal SBP reduction as follows:extreme dipper if the nocturnal SBP reduction was ≥20%;dipper if the fall was≥10% but <20%; nondipper if the fall was ≥0%but <10%; and riser if it was<0%. Venous blood samples were obtained from all subjects for measurement of routine blood chemical(including serum total cholesterol,triglyceride,high-density lipoprotein cholesterol,glucose,UA,FG),plasma catecholamines,plasma AngⅡand ET. The M-mode echocardiographic study of the left ventricle was performed. Left ventricular mass,left ventricular internal diameter,posterior wall,interventricular septum were used as the index of left ventricular hypertrophy.Results ①EH subjects were subclassified according to MS: MP+,n=22(31%);MP-,n=48(69%).Subjects were also subclassified as:extrem-dippers(n=15),dippers(n=25),non-dippers(n=18),risers(n=12).There were 10(44%) extrem-dippers and 2(9%)risers in the MP+ group.② Morning,day and night BPs were significantly higher in the EH group than in the NS group(P<0.01).The MP+ group had a significant increase in both systolic and diastolic BP compared with the MP- group during the whole morning period,whereas the daytime and the nighttime profile did not significantly differ between the two groups. Heart rates were no differences in the three groups ③ During AMBP, we detected that BP rose steeply after waking up in all subjects. But the mean BPs and heart rates were significantly increased between the preawake time and the afterawake time in the MP+ groups compared with MP- groups.(p<0.01). ④ The MP+ patients had higher LVM,LVMI and thicker IVST compared with the MP- patients, and LVPW,LVDd did not differ between the EH groups. The incidence of LVH was higher in the MP+ group compared with the MP- group(57%vs25%, p<0.01). Morning SBP,DBP and MS were significantly positively correlated with LVM,LVMI,IVST. ⑤ The plasma E and AngⅡ concentrations were higher in the MP+ patients compared with the MP- patients (p<0.05). The plasma NE and ET concentrations were not different in the EH groups.⑥ Extrem-dipper patients had higher LVMI and thicker IVST compared with dippers. Riser patients had thicker IVST,LVPW compared with dippers, and echocardiographic parameters did not differ between non-dippers and dippers.Conclusions ① Approximately 1/3 EH patients have morning high blood pressure. ② Morning sympathetic and renin-angiotensin system overactivity coexist in hypertensive patients with morning BP surge, and they might be principal factors influencing the circadian pattern of blood pressure. ③Morning blood pressure significantly correlates with LVH, and they might contribute to raised cardiovascular risk in these patients. ④ The abnomal diurnal BP variation is associated with LVH, and is a predict index for target organ damage in EH patients...