Clinical Findings in Hypertension

Blood pressure is a continuous variable with a reasonably normal, or bell-shaped-curve, distribution across the general population. High blood pressure has been classically defined as a diastolic pressure of greater than 90 mm Hg, a systolic pressure greater than 140 mm Hg, or both. The higher the blood pressure, the greater the risk of a cardiovascular events; conversely, the lower the blood pressure, the lower the cardiovascular risk. It is important to stress that isolated systolic hypertension, a systolic pressure of greater than 140 mm Hg with a diastolic pressure of less than 90 mm Hg, is abnormal and requires attention.
The diagnosis of hypertension should not be based on measurements taken at a single office visit. Elevated readings should be confirmed at a second or third visit to establish the diagnosis, and any factors that might elevate blood pressure should be excluded. For example, the patient should refrain from smoking for at least 30 min prior to blood pressure measurement. The blood pressure should be measured, with a cuff of the appropriate size, after at least 5 min of rest in a seated or supine position. The cuff should cover approximately one third of the length of the upper arm and should completely or almost completely encircle the arm. Too small a cuff may overestimate the true blood pressure because it may only partially compress the artery, requiring a higher pressure for total occlusion. The measurements should be made twice in both arms, for a total of four measures. The average of the two measurements in the arm with the higher values is used as the baseline value of blood pressure. Systolic blood pressure is indicated by the phase 1 Korotkoff sound (onset) and diastolic pressure by phase 5, or disappearance, in adults. In children, phase 4, or muffling, has been suggested as the best indicator of diastolic pressure.
The blood pressure obtained in the physician's office, however, does not always accurately represent that experienced by the patient during routine daily living. About 20–30% of patients with mildly elevated office blood pressure may have a hyperadrenergic response to having their blood pressure measured. This hyperreactivity is called white-coat, pseudo-, or office hypertension and may be related to anxiety from merely being in the physician's office or clinic. If the blood pressure is measured in a nonthreatening situation by a friend or relative or with an automated device, the blood pressure in these individuals may be normal. Blood pressure hyperreactivity should be suspected in patients who have persistently elevated blood pressure in the office and normal pressure measurements out of the office or in patients who have hypotensive symptoms but remain hypertensive in the office despite therapy. It has not been clearly established whether the blood pressure in these individuals is truly normal or whether they have an early or different form of hypertension. Several studies have found alterations in cardiac structure and function that are somewhere between those found in normotensive subjects and those found in hypertensive patients. No large outcome studies are available.
The best way to evaluate a patient with suspected white-coat hypertension is to use an automated ambulatory blood pressure device that measures the blood pressure periodically throughout the day and night. The patient quickly becomes accustomed to the small, light-weight, portable device, and a representative series of recordings can be obtained. The accuracy of these devices allows separation of those patients with true elevations of blood pressure from those who are hyperreactors. The devices are also useful in evaluating patients with episodic hypertension and those with borderline blood pressure elevations who already have evidence of involvement of the heart, kidneys, or vasculature. Automated blood pressure monitoring can be used to evaluate the duration and effectiveness of antihypertensive medication; correlate blood pressure with damage to the heart, kidneys, or blood vessels; and determine the prognosis. Its value in routine evaluation of hypertensive patients has not been clearly established, however.