Dispersion of Blood Pressure and Heart Rate in Essential Hypertension

The dispersion of the cardiovascular control system variables of heart period, systolic and diastolic blood pressure in a group of resting essential hypertensives has been compared with a group of normotensive subjects. Controlled variable dispersion in the absence of external perturbation was considered to be a measure of short term cardiovascular control system offset (error) from reference values (setpoint). The high blood pressure group demonstrated a greatly decreased controlled variable dispersion compared with the normal, implying the operation of a control system having a high closed loop gain, low system error and poor stability secondary to perturbation or stress. The extent of the changes in control system performance in essential hypertension was reduced by the adrenergic neuron blocking agent, guanethidine. These conclusions are consistent with and are discussed in relation to the known dynamic responses of heart rate and blood pressure to stress, together with the pathophysiology of the forward and feedback pathways of the cardiovascular control system, in essential hypertension.