The measurement includes:
- Systolic blood pressure (SBP)
- Diastolic blood pressure (DBP)
- Mean arterial pressure (MAP)
- Pulse pressure (PP)
- Augmentation index (Aix)
- Pulse wave velocity on the aorta (PWV)
- Length of cardiac cycle in m/sec (Period)
- Systolic area index (SAI)*
- Diastolic area index (DAI)*
*The last two data refers to the perfusion pressure state of the coronaries.
The measured Aix and PWV values are automatically evaluated by the device in terms of the optimum, normal, elevated or pathologic range of values.
The meaning of Pulse Wave Velocity (PWV) and Augmentation index (Aix)
Nowadays, in clinical practice, the pulse wave velocity (further on the PWV) is generally applied to the PWV of the aorta, because this is where the reduction of the flexibility of the vessel wall (caused by development of the atherosclerosis) is evident at the early stage. The PWV and the augmentation index (Aix) are used mostly for the non-invasive examination of the arterial stiffness. The aortic PWV can be determined on the basis of the time difference between the pulse waves appearing in the art. carotis and on the art. femoralis, as well as on the basis of the velocity measured by the determination of the distance between these two points, calculated by the formula
V=S/T
The augmentation index, given in percents, (further on the Aix), is defined as the pressure difference between the first (P1), the early, (induced by the heart systole) and the second (P2), the late (appearing because of the reflection of the first pulse wave) systolic peaks, divided by the pulse pressure.
Aix (%) = (P2 – P1) / PP × 100
How conditions of the vascular system are assessed by Arteriograph?
The stiffer the wall of the aorta (atherosclerosis), the higher the PWV value is. Value above 12 m/s is unambiguously accepted as pathologic, because it has been proved that the survival rate with patients having PWV value above this limit will significantly grow worse.
The Aix, first of all, gives information on the resistance of the arterioles. The higher the percentage value of the Aix is, the stronger the resistance of the arterioles (resistance vessels). Peripheral resistance of the arterioles is essentially influenced by the endothelium. In case of endothel dysfunction, the volume of the nitrogen monoxide (NO) output in the endothelium will decrease, this is the reason of its vasotonic effect, the peripheral resistance will grow (further on TPR = Total Peripheral Resistance).