FFR: pitfalls
Gabor Toth G.
Cardiovascular Centre Aalst
OLV-Clinic Aalst, Belgium
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Fractional flow reserve measurement
X
X
Accurately measured coronary pressure (Pd)
Accurately measured aortic pressure (Pa)
X
Maximal hyperaemia
X
FFR
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Pitfalls can be related to....
Preparation
• Calibration
• Equalization
Measurement
• Drifting
• Wedging
• Whipping
• Hyperaemia
Tracing interpretation
• Cursor position
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Pitfalls can be related to....
Preparation
• Calibration
• Equalization
Measurement
• Drifting
• Wedging
• Whipping
• Hyperaemia
Tracing interpretation
• Cursor position
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Calibration
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
‘teaching’ the system,
what is zero pressure
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Calibration: PressureWire
• Fill the tube of the wire with saline
• Wait a 30-60 sec to have the wire
completely and stably wet
• Perform calibration afterwards
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Equalization
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
‘teaching’ the two systems,
to be synchronous
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Equalization
Pa = Pd
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
After equalization
DO NOT CHANGE YOUR SETTING
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Pitfalls can be related to....
Preparation
• Calibration
• Equalization
Measurement
• Drifting
• Wedging
• Whipping
• Hyperaemia
Tracing interpretation
• Cursor position
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Pitfalls can be related to....
Preparation
• Calibration
• Equalization
Measurement
• Drifting
• Wedging
• Whipping
• Hyperaemia
Tracing interpretation
• Cursor position
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Drifting
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
When the two
systems forget to be
synchronous...
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Clues to identify drift
• Curves are identical in shape
• Curves are shifted paralell
• Dicrotic notch is well visible on both
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Gradient or Drift??
True Gradient
Drift
Different morphology
Dicrotic notch not visible
Same morphology
Paralell shifting
Dicrotic notch well visible
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Post-measurement check
Pa =≠ Pd
ETP course 2014, Sophia-Antipolis
Measure
Equalize
Drift!!!
again
FFR: pitfalls
Wedging
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Aortic pressure is
inaccurately measured...
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Size of the guiding catheter
Induced
area stenosis
6F
4 mm
1.8 mm
20 %
4 mm
2.1 mm
27 %
4 mm
2.4 mm
36 %
7F
8F
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Size of the guiding catheter
Induced
area stenosis
6F
3 mm
1.8 mm
36 %
3 mm
2.1 mm
49 %
3 mm
2.4 mm
64 %
7F
8F
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Wedging guiding catheter
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Disengaged guiding catheter
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Wedging guiding catheter
FALSE VALUE 0.88
ETP course 2014, Sophia-Antipolis
TRUE FFR 0.66
FFR: pitfalls
Whipping
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Coronary pressure is
inaccurately measured...
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Whipping
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Hyperaemia
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Without maximal
hyperaemia there is
no FFR measurement
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Insufficient
hyperaemia
Underestimation of
the gradient
Overestimation of
the FFR
Underestimation of
disease
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Pitfalls can be related to....
Preparation
• Calibration
• Equalization
Measurement
• Drifting
• Wedging
• Whipping
• Hyperaemia
Tracing interpretation
• Cursor position
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Pitfalls can be related to....
Preparation
• Calibration
• Equalization
Measurement
• Drifting
• Wedging
• Whipping
• Hyperaemia
Tracing interpretation
• Cursor position
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Position the cursor to the lowest value
where indeed FFR was measured
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Position the cursor to the lowest value
where indeed FFR was measured
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Pitfalls can be related to....
Preparation
• Calibration
• Equalization
Measurement
• Drifting
• Wedging
• Whipping
• Hyperaemia
Tracing interpretation
• Cursor position
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Fractional flow reserve measurement
Obtain accurate measurements
Induce proper maximal hyperaemia
Interpret the tracing appropriately
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Thank you for your attention!
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Thank you for your attention!
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Setting in the cathlab
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Calibration: Position of the Transducer
• Aortic pressure is measured by the fluid filled
guiding catheter
• Its value is a relative pressure, compared to
the reference, measured at the transducer
• Height of the transducer has a measurable
impact on the value
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Calibration: Position of the Transducer
Pressure
TOO LOW
Pressure
OK
Pressure
TOO HIGH
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Calibration: Position of the Transducer
Pressure
TOO LOW
Pressure
OK
Pressure
TOO HIGH
ETP course 2014, Sophia-Antipolis
FFR: pitfalls
Setting in the cathlab
ETP course 2014, Sophia-Antipolis