Systemic arterial hypertension is one of major risk factors to development of target organ damage that culminate in cardiovascular diseases such as acute myocardial infarction and stroke. Sodium intake is related with elevation of arterial blood pressure due to rise of cardiac output and of arterial stiffness and it can be estimated by daily sodium excreted in urine 24h. Ambulatory Blood Pressure Monitoring can be used to obtain peripheral and central hemodynamic parameters [arterial stiffness parameters - central blood pressure, pulse wave velocity and augmentation index]. Applanation tonometry also can be used to check same central hemodynamic parameters. Both methods provide us important informations about the patients clinical conditions and help us to infer their prognosis. Therefore, this protocol aims measure the central hemodynamic parameters in hypertensive patients, controlled or resistant, and evaluate their sodium urinary excretion. The hypothesis is the resistant hypertensive patients have parameters higher than controlled hypertensive patients.

The urinary sodium (Na+) will be evaluated by flame photometry. Excretion of urinary sodium will be calculated by multiplying the urinary sodium concentration in mE /L by 24-hour urinary volume. Two to three urinary Na+ samples will be collected within six months.

3.3.3 ABLOOD PRESSURE MONITORING - 24 HOURS Ambulatorial blood pressure monitoring 24-hour will be performed using a Mobil-O-Graph® compact digital device (version 12, ambulatory pressure monitor, 2000, UK). Individuals will be instructed to maintain their normal activities of daily living. The device will be pre-programmed to measure blood pressure within 24 hours at 30-minute intervals every hour during the waking period and at 1-hour intervals during sleep. This device will evaluate the following parameters: systolic and peripheral diastolic blood pressure, mean arterial pressure, pulse pressure, systolic central aortic pressure, central diastolic aortic pressure (cDBP), central pulse pressure (cPP), augmentation index corrected for 75 bpm (AI75%) and pulse wave velocity (PWV).

Inclusion Criteria:

• over than 18 years old;
• hypertensive patient for more than four weeks;
• controlled hypertension;
• resistant hypertension;
• regular patient in the local where the study will be done.

Exclusion Criteria:

• chronic renal failure in dyalisis;
• been in the hospital in last 60 days;
• used vasoactive drugs in last 30 days;
• heart failure in III or IV functional class (NYHA);
• pregnant/breastfeeding;
• serious liver disease;
• HIV positive;
• psychiatric diseases that make it difficult to participate;
• stroke or acute myocardial infarction in last 30 days;
• cancer with prognosis less than one year.

Individuals will be selected from the hypertensive patients who are assisted in the health service where the study will be performed.