Conventional methods for arterial pressure (AP) measurement are not capable of identifying it in each cardiac cycle. Besides, they ignore many significant factors. The paper reports on an innovative method based on cardiac cycle phase analysis for detecting systolic and diastolic AP changes in each cardiac cycle using synchronous digitally processed ECG and Rheo recordings. Considered is the phase mechanism of the natural diastolic pressure regulation. The diastolic AP changes referred to the physiological norm and aortic dilatation status are also assessed.