Piezo-electric Versus Open Wire Pressure Guidewires for FFR Measurements: Comparison of Two Commercially Available Pressure Wires

FFR is a lesion-specific pressure-derived index of functional severity, defined as the maximum myocardial blood flow in the presence of an epicardial stenosis compared with the maximum flow in the hypothetical absence of the stenosis. FFR is measured by advancing a pressure guidewire into the coronary artery distal to the lesion under investigation and maintained in that position. Distal coronary pressure (Pd) and aortic pressure (Pa) are measured simultaneously while inducing steady state maximum hyperemia. FFR is defined as the lowest value of Pd/Pa achieved during maximum hyperemia. An FFR value = or < 0.80 indicates the presence of myocardial ischemia and indicates PCI is warranted.

Existing 0.014" wires with pressure measurement capabilities have been available for more than 20 years. Improvements have been done over time, but they are still regarded as inferior to ordinary guidewires when it comes to maneuverability and general guidewire properties. This is attributed to the microelectronics that are needed to facilitate the pressure measurements in these wires. These existing wires also have issues with signal stability which is often referred to as 'drift'. Drift is an electronical phenomenon that leads to a slow progressive change in the pressure value over time. a not entirely reliable signal quality.

A relatively new pressure guidewire, Wirecath, is an equivalent device to the currently commercially available pressure guidewires. In comparative bench tests it has shown very good maneuverability. Moreover due to the 'open wire' technology (and thus lack of microelectronics throughout the wire), the Wirecath has very stable signal properties and is, according to physical law and bench testing, immune against a hydrostatic error and less affected by drifting of the signal, which are limitations with current pressure guidewires.

This study is designed to examine and compare the pressure measurements of two commercially available pressure guidewires (Abbott and Cavis Technologies) by simultaneously measuring FFR in the same coronary artery with two different pressure guidewires.