What is the Origin of Augmentation Index?

This index is a product of clinical hemodynamics and pulse wave analysis, developed as a robust, non-invasive method for assessing arterial health and biological aging of the vasculature. "Augmentation" refers to the increase in central pressure caused by the early return of the reflected wave, and "Index" denotes its standardized, calculated metric. This parameter offers superior prognostic information compared to traditional brachial blood pressure readings.

What is the Mechanism of Augmentation Index?

The heart generates a forward-traveling pressure wave during systole, which propagates along the arterial tree and reflects back from peripheral resistance sites and major arterial bifurcations. In a healthy, compliant artery, the reflected wave returns late in diastole, aiding perfusion. However, with increased arterial stiffness, the wave travels faster, returning earlier in late systole and 'augmenting' the peak central systolic pressure, thereby increasing the heart's afterload and oxygen demand.

Augmentation Index ∞ Area

Augmentation Index

Meaning

The Augmentation Index (AIx) is a quantitative, non-invasive clinical measure of arterial stiffness and the magnitude of the pressure wave reflection in the central arterial tree. It quantifies the degree to which the reflected pressure wave contributes to the peak systolic pressure, particularly in the aorta. A high augmentation index is a direct physiological marker indicating increased vascular rigidity and peripheral resistance, correlating with elevated cardiovascular workload and risk.