Computational system for noninvasive estimation of FFR – Coronary Fractional Flow Reserve.

Currently, the limitations of coronary angiography in assessing the functional severity of a stenosis and the consequent existence of myocardial ischemia in the affected territory are well known (especially regarding moderate lesions, i.e., stenosis with a diameter reduction between 40-70%). In order to assess the impact of the injury on myocardial perfusion, several methods have been proposed to measure or estimate the blood flow through the lesion. In particular, the FFR index incorporates the existing blood supply by collateral vessels: this is one of the main features that results in a robust clinical parameter (values lower then 0.75-0.80 are indicative of the presence of risk of myocardial ischemia). However, the FFR measurement requires invasive coronary manipulation during cardiac catheterization. It also requires pharmacological induced hyperemia usually obtained by infusion of adenosine. These characteristics, together with the high costs of the procedure itself, hinder the democratization of the method and its availability on a large scale, both in the public health system as in private services. It is in this scenario that the development of computational models capable of modeling the main and collateral blood flow are needed: this is the big scientific technological innovation to be developed in order to provide a low-cost non-invasive alternative (called CE_FFR) to estimate the value of FFR.

Impact

From an economic point of view, the CE_FFR implies significant costs savings. This is so because it only requires a low cost CT angiography, while the FFR test requires costly inputs, highly trained medical professional and accessory medical staff that must be present during the endovascular procedure. The availability of this computational system would allow the use of a noninvasive procedure with equivalent precision of the invasive method. Besides that, due to its low cost, this procedure could be largely used in the public health system. Finally yet importantly, seeing that it is a noninvasive technique, CE_FFR would have a highly positive impact on the well-being of the patient.

Methodologies for testing the computational system

The methodology to be used can be resumed as: to research, to develop and to implement a noninvasive technique based on medical imaging, computational models and numerical simulation of blood flow in the arterial tree in order to computationally estimate the value of the fractional flow reserve (FFR), which will be named CE_FFR. This methodology will be compared with the values of FFR measured invasively in routine Incor procedures (HC, FM-USP, SP) before and after angioplasty procedures and/or deployment of stents.

Specifications and results to be provided by the computational system

Anatomically detailed and highly accurate 3D reconstruction of patient’s coronary arterial tree.

• Distributed CE_FFR values, i.e. regarding all points of each artery of patient’s arterial tree.
• Computational planning of angioplasty procedure and/or employment of stents with their respective CE_FFR values.