High Blood Pressure

Blood pressure is defined by two values: systolic (contraction of the heart), the highest value, and diastolic (dilation of the heart), the lower. "The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure" (JNC-VI) and the World Health Organization/International Society of Hypertension Guidelines subcommittees have agreed that both systolic and diastolic blood pressure should be used to classify hypertension. Systolo-diastolic hypertension is diagnosed when systolic and diastolic blood pressure are over 160 and 90, respectively. Isolated systolic hypertension refers to systolic blood pressure over 160 and diastolic blood pressure under 90.

Misdiagnosis may be more frequent in the elderly due to various factors, including inappropriate length of the cuff due to obesity or very low weight, fluctuations in blood pressure due to postural hypotension, and/or anxiety (white coat effect). The difficulty of measuring blood pressure in elderly persons should encourage the development of ambulatory blood pressure measurement.

Ambulatory blood pressure measurement is most useful for identifying patients with white-coat hypertension, also known as isolated clinic hypertension, which is arbitrarily defined as a clinc blood pressure of more than 140 mmHg systolic or 90 mmHg diastolic in a patient with daytime ambulatory blood pressure below 135 mmHg systolic and 85 mmHg diastolic.