ABSTRACT
The emergence of sensor-tipped angioplasty guidewires has enabled invasive coronary angiography to move beyond simple anatomical lumenographic assessment into the realms of physiological assessment. Under hyperaemic flow conditions, coronary microvasculature resistance (CMVR) is minimised, autoregulatory responses are abolished and flow becomes dependent upon pressure. The relationship between flow and pressure under maximal hyperaemia is relevant to understanding the rationale behind indices of coronary physiology. Whilst these basic haemodynamic laws remain central to understanding coronary physiology, they are a simplification based upon idealised circumstances which fail to fully capture the complex haemodynamic effects of vessel tortuosity or the effects of dynamic vascular flow. Using FFR to guide coronary revascularisation in the cardiac catheter laboratory is associated with a number of advantageous clinical and economic outcomes. FFR is based upon the assumption that maximal, stable hyperaemia can be consistently attained with a standard dose and regimen of adenosine.
