Fractional flow reserve (FFR) is a medical wire-based procedure which is used to accurately measure the blood pressure and flow through a particular part of the coronary artery. This procedure is performed at the time of a cardiac catheterization through a standard diagnostic catheter. The results of the test help the doctor to assess if angioplasty and stenting should be performed in case of intermediate or less complicated blockages.
The main purpose of removing blockages is to open up the narrowed coronary arteries to allow the blood flow to the heart properly. This invasive measurement procedure helps to assess if performing a stenting or angioplasty procedure will help the patient, in case he/she has a minor or an intermediate blockage. Today, the procedure is considered very effective since it helps to eliminate the wrong procedure and analyze other alternative treatment options.
Effectiveness of Fractional Flow Reserve
Initially, the procedure was only used to check the procedural needs of patients with single-vessel problem. However, with recent advancements in medicine, the same can be used to effectively help the patient suffering from conditions such as:
- Multi-vessel disease
- Acute coronary syndrome
- Left main lesions
- Bifurcation and ostial branch stenoses
- Sequential stenoses
- Diffuse stenoses
- Bypass grafts
However, no absolute measurements of the fractional flow reserve test are the sole deciding factor and hence, necessary diagnostic tests and procedures will need to be conducted to take the final call.
The procedure of Fractional Flow Reserve
The procedure of fractional flow reserve requires a guiding catheter, a pressure monitoring guidewire and a hyperemic stimulus for measurement. The pressure wire is connected to an interface, which displays the FFR values and pressure signals. A calibrate pressure wire is placed outside the patient.
Then the pressure wire is directed into the guiding catheter through the introducer needle. Once placed, the pressure is advanced into the coronary artery beyond the stenosis, while the sensor is placed at least 2cm beyond the stenosis.
Post this, a stimulus is administered intravenously or through an intracoronary route via the guide catheter. The values will then be displayed on the monitor. Aortic pressure is recorded from the guide catheter and distal pressure is measured from the sensor to arrive at the FFR ratio.
Interpretation of Fractional Flow Reserve Results
All FFR values below 0.75 indicate that stenosis or other procedure is significant and hence, should be performed to improve the condition of the patient. While values of FFR above 0.80 indicate that since the patient has minimal hemodynamic significance, the procedure can be safely deferred. However, if the values of the test fall between 0.75-0.80, the decision solely depends on the discretion of the doctor.
Advantages of Fractional Flow Reserve
- FFR is a simple procedure which is very easy to perform
- There are low chances of variability in the results
- FFR can be accurately measured in 99% of the arteries
- Compared to other invasive assessments, FFR has valuable and unique characteristics
- These values are more reliable since they are not affected by changes in the heart rate, blood pressure, or myocardial contractility
- The results may help to accurately identify the hemodynamic significance of stenosis in case of an epicardial coronary artery
- It can also help the surgeons assess the need for a specific lesion, especially if the patient has multi-vessel coronary artery disease
- The test results are of even more significance since they take into account the collateral blood supply to maximal myocardial perfusion
- FFR can be effectively used to rule out procedures which will not help the patient’s condition. It helps to assess bifurcations and eliminate branch vessel stenting, if not required.
- Helps save a lot of healthcare costs and improve the number of operations successful
- Helps select better cases for treatment
Disadvantages of Fractional Flow Reserve
- The basic disadvantage of the fractional flow reserve method is that it is invasive in nature and can have slight complications, though they are easily treatable
- Even though the procedure is very simple, the measurements are hugely dependent on achieving maximal pharmacologic vasodilation
- Though rarely, but value from the fractional flow reserve test can be influenced by some pathological factors
Application of Fractional Flow Reserve
This test can be of most use in situations such as, where a lesion measures 50 per cent on the coronary angiogram but there have been no symptoms such as chest pain or angina. In such a case, the cardiologist might decide to stent the lesion to remove the blockage. However, since there were no symptoms, maybe a stenting procedure was not required. In this case, even a special guide wire might reveal that an intervention such as stenting will not have a significant impact on the specific blockage. This helps to eliminate unnecessary healthcare costs for the patient and also more effectively contribute to their care.
Overall, an FFR procedure is very helpful though its significance and dependency on its results are to be solely decided by the medical practitioner.