What is orthostatic hypotension?

It is a sudden drop in blood pressure, which is noted as the patient is quickly returned to an upright position in the dental chair.

Orthostatic hypotension is defined as a decrease in systolic blood pressure of 20 mm Hg or a decrease in diastolic blood pressure of 10 mm Hg within three minutes of standing when compared with blood pressure from the sitting or supine position.

This condition is due to disturbances of the autonomic nervous system, and is the second most frequently observe cause of transient loss of consciousness in the dental patient after fainting.

Almost any disease of the spinal cord can be accompanied by orthostatic hypotension. Many conditions usually manifesting as peripheral neuropathies can be accompanying autonomic neuropathy and orthostatic hypotension. These include amyloidosis, Guillain-Barré syndrome, diabetes, bronchogenic carcinoma.
What is orthostatic hypotension?

Definition of renovascular hypertension

In most Westernized countries, and especially among older individuals, renovascular hypertension is the most remediable cause of elevated blood pressure.

Renovascular hypertension is a reversible cause of hypertension secondary to a decrease in renal perfusion pressure which activates the renin-angiotensin system and leads to the release of rennin and the production of angiotensin II.  It is a progressive disorder that can result in serious complications without adequate treatment.

Angiotensin II increases sodium reabsorption and induces postglomeruler and systemic arterial vasoconstriction, causing renovascular hypertension. The prevalence of renovascular hypertension was estimated at about 5% of all hypertensive individuals but it is varied form less than 1% to more than 50% depending on the degree of screening in the study population.

With prevalence of about 5%, renovascular disease represents the most frequent cause of secondary hypertension.

Unlike the diagnosis of most other cardiovascular and nephorologic conditions, renovascular hypertension can be diagnosed only retrospectively, by means of a physiologic blood pressure (BP) response to an intervention.
Definition of renovascular hypertension