What is a fractional flow reserve measurement?
A fractional flow reserve (FFR) is a procedure done during cardiac catheterization to estimate the degree of blockage in the coronary arteries. It is a guide wire-based procedure that determines the ratio between the maximum achievable blood flow in a diseased blood vessel (coronary artery) and normal maximum flow.
An FFR is measured at the time of coronary angiogram or cardiac catheterization using a pressure wire. If an FFR does not reveal any significant obstruction, the physician will prefer medical therapy.
When is a fractional flow reserve measurement indicated?
A fractional flow reserve measurement is indicated:
- To identify the extent of coronary stenosis (the narrowing of blood vessels)
- To identify the culprit block in the multiple blood vessels
- To identify the exact location of the block in the case of an unclear angiographic image
- To determine if a particular obstruction requires an angioplasty or a coronary bypass graft (CABG)
However, individuals with asthma should avoid undergoing the fractional flow reserve procedure.
How is a fractional flow reserve measured?
Before the procedure
- The physician will explain the risks and benefits of the procedure to the patients.
- You need to sign an informed consent before the procedure.
- You should clarify all your concerns with the physician regarding the procedure.
- The physician may perform a cardiac catheterization to identify the need for a fractional flow reserve.
- There are some potential discomforts associated with the procedure such as
- Blood thinners would be given to you before the surgery.
- Your physician would ask you to stop medications such as theophylline 12 hours before the surgery.
During the procedure
- The physician performs a fractional flow reserve under sedation.
- You will lie flat on the operating table, then the physician inserts a thin guide wire through a catheter during an angiogram.
- Once the special guide wire crosses the block, the physician infuses a medicine such as adenosine into the blood vessel that increases blood flow (hyperemic). This will measure the flow and pressure of the blood.
- The fractional flow reserve value is displayed on the monitor attached. The higher the fractional flow reserve value, the lower the chances of any abnormality.
- Usually, a fractional flow reserve value of one is accepted as normal, whereas values lower than 0.75 generally indicate a heart attack.
What are the complications of a fractional flow reserve procedure?
The risk associated with a fractional flow reserve is low, but complications are associated with cardiac catheterization. These include