Many mechanisms have been proposed to account for the rise in peripheral resistance in hypertension. Most evidence implicates either disturbances in the kidneys' salt and water handling (particularly abnormalities in the intrarenal renin–angiotensin system) or abnormalities of the sympathetic nervous system. These mechanisms are not mutually exclusive and it is likely that both contribute to some extent in most cases of essential hypertension. It has also been suggested that endothelial dysfunction and vascular inflammation may also contribute to increased peripheral resistance and vascular damage in hypertension. Interleukin 17 has garnered interest for its role in increasing the production of several other immune system chemical signals thought to be involved in hypertension such as tumor necrosis factor alpha, interleukin 1, interleukin 6, and interleukin 8.
A blood pressure reading measures both the systolic and diastolic forces, with the systolic pressure listed first. The numbers show your pressure in units of millimeters of mercury (mm Hg)—how high the pressure inside your arteries would be able to raise a column of mercury. For example, a reading of 120/80 mm Hg means a systolic pressure of 120 mm Hg and diastolic pressure of 80 mm Hg.
One especially important cause of low blood pressure is orthostatic hypotension, which is sometimes referred to as postural hypotension. This happens when blood pressure drops rapidly during changes in body position—usually when changing from sitting to standing—inducing classic signs that the blood pressure is too low, like dizziness, blurry vision, and fainting.
If dehydration contributes to the problem, increased fluid intake would be needed based in part on your body mass index (BMI). For example, a person with a normal BMI would likely only need eight to ten 8-ounce glasses of water per day to maintain ideal hydration. People with a high BMI may need far more. Adding more salt to your diet may also aid in normalizing your blood pressure.
Vasovagal syncope can be treated with several types of drugs such as beta blockers, for example, propanolol (Inderal, Inderal LA) and selective serotonin reuptake inhibitors such as fluoxetine (Prozac), escitalopram oxalate (Lexapro), paroxetine (Paxil), sertraline (Zoloft), citalopram (Celexa), and fluvoxamine (Luvox). Fludrocortisone (Florinef) (a drug that prevents dehydration by causing the kidney(s) to retain water) also may be used. A pacemaker can also be helpful when a patient fails drug therapy.