The Effects of Nifedipine and Metoprolol on Blood Pressure Variability in Northern Chinese

Hypertension is one of the most common cardiovascular diseases, which is a major risk factor for stroke and cardiovascular events. Traditionally, cardiovascular risk stratification in hypertensive patients was based on the average blood pressure (BP) measured in the clinic. Accumulated data has shown that target-organ damage is related not only to 24-h mean intra-arterial BP, but also to BP variability (BPV) in subjects with essential hypertension. Growing evidence demonstrated that BPV has considerable prognostic value for all-cause mortality and cardiovascular outcomes, independent of average BP.

At present, the normal range of BPV is not very clear. There are many studies about the effects of different kinds of drugs on blood pressure, but the clinical researches about the impacts of antihypertensive drugs on BPV are limited, and the conclusion is still controversial.

Hypertension is one of the most common cardiovascular diseases, which is a major risk factor for stroke and cardiovascular events. Traditionally, cardiovascular risk stratification in hypertensive patients was based on the average blood pressure (BP) measured in the clinic. Accumulated data has shown that target-organ damage is related not only to 24-h mean intra-arterial BP, but also to BP variability (BPV) in subjects with essential hypertension. Growing evidence demonstrated that BPV has considerable prognostic value for all-cause mortality and cardiovascular outcomes, independent of average BP.

The hypertension prevalences in the high latitude and cold regions are much higher than those in the low latitude and warm regions. In China, the prevalences of hypertension are gradually increased from the South to the North. Heilongjiang province is the "high-risk" region for hypertension, with a prevalence of 30.48%. This may be due to the combined effects of lower average temperature and higher intake of salt and saturated fatty acid, which Increased sympathetic nerve excitability, and eventually lead to elevation of blood pressure. Therefore, it is essential to formulate the best treatment of hypertension according with the physical characteristics of northern Chinese.

At present, the normal range of BPV is not very clear. There are many studies about the effects of different kinds of drugs on blood pressure, but the clinical researches about the impacts of antihypertensive drugs on BPV are limited, and the conclusion is still controversial.

Eligibility Criteria:
Inclusion Criteria:

* Men aged between 18 and 75 included years old
* Postmenopausal women who are no more than 75 years older.
* Patients with essential mild to moderate uncomplicated hypertension (DBP\<110mmHg and SBP\<180mmHg measured with a validated automatic device in sitting position) after initiation or intensification of appropriate healthy lifestyle modification,
* Without antihypertensive treatment in 2 weeks.

Exclusion Criteria:

* History of cerebrovascular disease: ischemic stroke, cerebral haemorrhage and TIA.
* History of cardiovascular disease:unstable angina, myocardial infarction, coronary revascularization and congestive heart failure.
* History of renal impairment.
* History of Type I diabetes mellitus or Type II diabetes uncontrolled.
* History of liver impairment.
* History of alcoholism or drug abuse.
* Known symptomatic orthostatic hypotension.
* Contra-indications to treatment with investigate products.