Transonic HT331-FT - Appendix C: ECG Signal, D;S Ratio & DF

AU-OPR-AureFloFT-EN,
Rev H
39
Appendix C: ECG Signal, D/S Ratio & DF
DESCRIPTION
This appendix describes the display and analysis of the ECG signals with Transonic
®
FlowTrace
®
software.
When a “standard” ECG signal is displayed on the touch-panel display, FlowTrace
®
calculates and displays
Diastolic/Systolic Flow Ratio (Fig. C.1):
D/S Ratio =
Average Diastolic Volume Flow
Average Systolic Volume Flow
DIASTOLIC FRACTION (DF)
FlowTrace
®
offers the option of displaying the diastolic fraction (DF) instead of the D/S Ratio. The DF option
is found in the System Settings menu. See page 16 for instructions. The diastolic fraction is the percent of
diastolic volume ow compared to total (systolic plus diastolic) volume ow.
DF =
Diastolic Volume Flow
x100
Diastolic Volume Flow + Systolic Volume Flow
● A DF% >50% indicates a diastolic-dominant ow prole.
● A DF% approximating 50% indicates a balanced, diastolic-systolic, ow prole.
● A DF% <50% indicates a systolic dominant ow prole.
Transonic
®
recommends using the D/S Ratio instead of the DF for most situations. Use of the D/S Ratio will
make it easier for the CABG surgeon to follow the Transonic
®
proven coronary graft patency assessment.
Beating Heart Graft Patency assessment follows a straightforward decision tree:
1) ASSESS MEAN FLOW READING OF THE FLOWMETER
● Mean ow < 5 mL/min always indicates a technical error
● Mean ow >25 mL/min (or >20 mL/min on a small patient) indicates a well-functioning graft.
● If mean ow is inconclusive: between 5 and 25 (20) mL/min, Flow Waveform Assessment is
necessary.
Fig. C.1: ECG signal that will be recognized by FlowTrace
®
software. The R-peak of the QRS
complex is the highest peak of the signal; this is when the systolic contraction starts
to affect the ow waveform. The peak of the T-wave is the point where diastolic
relaxation starts to affect coronary ow. This is typically 200 msec after the R-peak.