Abstract
It is well known that emotional factors can influence cardiovascular dynamics markedly (for references see Wade & Bishop 1962). The procedure of cardiac catheterization causes a variable degree of anxiety in many patients and under these circumstances deviations from basal conditions can be expected. During recent years new methods have been introduced for catheterization of the left side of the heart. Some of these methods involve procedudes which could markedly alter the circulatory state of the resting patient. The deviation from basal conditions can be expected to vary considerably from one individual to another and in the same patient from moment to moment. For the evaluation of the circulatory conditions in the individual case it is therefore important to define the degree of deviation from basal conditions.