Learn with the Leaders in Physiology how to perform in just a few minutes CMD assessment using continuous thermodilution in just a few minutes. Dive into how the technology works.

An introduction to Microvascular Resistance Reserve (MRR)


The RayFlow infusion catheter is a rapid exchange (RX) double lumen catheter with a series of holes and a radiopaque marker on its distal part intended to be used in adults:

– To infuse saline or other appropriate solutions into the coronary vasculature.
– To allow continuous thermodilution with the use of a 0.014’’ pressure/temperature guidewire.

A dedicated design with a double lumen with inner and outer laser ultra-thin holes allows to infuse fluids in a continuous manner (saline, medication or contrast media) into the blood vasculature resulting in a homogeneous mixing. 

The microcatheter hub is compatible with any automated pump injector used for the continuous infusion of saline/liquid at room temperature. 

The RayFlow catheter used in combination with a specific pressure/temperature guidewire allows to assess in a reproducible manner the coronary Microvascular Dysfunction (CMD). This technology based on continuous thermodilution provides unvaluable quantified information such as the absolute blood flow measurements (ml/min) and the microcirculation resistance assessment (Wood units). 

RayFlow rapid-exchange microcatheter before and during infusion. 

Coronary Microvascular Dysfunction (CMD)

In the cardiac field, the RayFlow is the key to open a new window (the so-called « Black Box » in cardiology) to diagnose and treat patients suffering with persistent angina and non-obstructive coronary arteries. Too often these patients remain undiagnosed and up to 1 in 2 of these patients have CMD. Continuous thermodilution is potentially a new approach to offer an innovative solution to diagnose these patients affected by Angina or Myocardial Infarction with Non Obstructive Coronary Arteries (ANOCA or MINOCA).

Continuous vs bolus thermodilution

The RayFlow microcatheter is the new tool to assess physiology using continuous thermodilution and set a new standard offering:

– Higher repeatability,
– Faster procedure,
– Operator independent procedure and results,

Comprehensive full set of physiology results:

Absolute Coronary Blood Flow (mL/mi)           
Microcirculation Resistance (Wood)                  
Epicardial Microcirculation Resistance (Wood)
Global Microcirculation Resistance (Wood)    
Coronary Flow Reserve                                 
Microvascular Resistance Reserve                      

FFR =   Pd/ Pa
Q = ( Ti / T  ) x 1,08 x Qi
R micro  =   Pd/ Q
R epi =   Pa-Pd/ Q
R total =   Pa/ Q
CFR =   Qhyper/ Qrest

Equipment to perform a RayFlow  procedure

To perform continuous intracoronary thermodilution the following pieces of equipement are required:

– A dedicated monorail infusion microcatheter (RayFlow, Hexacath), with 4 external side holes and 2 internal side holes to enable instantaneous and complete mixing of saline solution and blood in the very proximal part of the artery under study,  

– A 5F minimum guiding catheter for radial or femoral approach,

– A dedicated pressure/temperature wire. The sensor must be placed in the distal third of the artery as for pressure measurements, 

– A regular power injector or high-pressure infusion pump to infuse saline solution at a steady flow rate ranging from 8 to 20 mL/min over several minutes. The fine tuning of the pump should be possible by steps of 1 or 2mL/min, 

– A Coroventis software to display all measurements in real time,

– Heparinized or regular saline solution.

RayFlow microcatheter positioning

Learn How to perform a RayFlow procedure with the leaders 

Ordering information

Stock number :

  • RFW6 : All countries (except US)
  • RFW62U: USA