Pulse amplitude
The heart works in two phases, the contraction phase (ejection phase, systole ) and the relaxation phase (filling or resting phase, diastole ). It therefore only creates pressure during the contraction phase. The difference between the peak pressure of the systole and the minimum pressure at the end of the diastole is the pulse amplitude , also known as the pulse pressure ( English pulse pressure , abbreviated to PP ) or the blood pressure amplitude .
The blood is ejected into the large vessels. These are not rigid tubes, but elastic hoses. Thanks to their elasticity, they expand and soften the rise in pressure, otherwise the pressure would rise very high during the ejection phase. Accordingly, during diastole, when the heart relaxes and fills with blood again, the pressure does not drop to zero. Again thanks to the elasticity of the vessels, the pressure drops only slowly to the minimum value, the diastolic value of the cardiac cycle. This pressure-equalizing function of elastic vessels will air vessel function called - in analogy to technical systems where a piston pump with an air chamber is combined with the exact same purpose of pressure equalization.
The level of the pulse amplitude is essentially determined by the elasticity of the vessels, the volume ejected by the heart and the duration of the diastole. Since the elasticity decreases with the development of arteriosclerosis , the systolic pressure can increase in isolation: This creates isolated systolic hypertension .
There are no generally recognized norms or normal values for pulse pressure, but values around or below 50 mmHg are classified as normal, including by many blood pressure monitor manufacturers . It is widely assumed that there is a need for treatment from around 65 mmHg.