Pressure- and 3D-Derived Coronary Flow Reserve with Hydrostatic Pressure Correction: Comparison with Intracoronary Doppler Measurements

Figures

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  Figure 1. Calculation of CFR and RRR values during FFR measurement. The method for calculating CFRp-3D and RRRp-3D uses hemodynamic calculations combining intracoronary pressure data (top left panel) and 3D anatomical parameters (bottom left panel). Based on the hyperemic and resting pressure data, as well as 3D anatomical parameters, simple hemodynamic equations were used to calculate resting and hyperemic flow, CFR, and RRR. The detailed description of the flow calculations is described in the patent of the method: https://patents.google.com/patent/WO2019175612A2/en (accessed on 5 March 2022).

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  Figure 2. Results of simultaneous pressure and flow measurements by the ComboWire. In this case, the average proximal (aortic) and distal pressures were detected to be 95 mmHg and 88 mmHg, respectively. At maximal hyperemia (P), the average peak velocity (APV-P) increased to 29 cm/s from the basal (B) velocity of 10 cm/s (APV-B) parallel with the increase in the pressure drop (the proximal and distal pressures were 89 mmHg and 79 mmHg, respectively). The measured FFR was 0.89, while the CFR was 2.9 (Case 10).

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  Figure 3. The height difference between the LAD orifice and the sensor position. After 3D reconstruction, the height difference between the orifice and the pressure wire sensor was transformed to mmHg getting hydrostatic pressure (red) (Case 10). This value (5.58 mmHg) influences the gradient between the aortic pressure at the tip of the catheter and the pressure detected by the sensor of the pressure wire, and it has a great impact on the results of the CFR calculation.

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  Figure 4. Correlations and agreements between calculated CFRp-3D values without and with hydrostatic offset correction, and the measured Doppler CFR values. (A,B) Correlations between the calculated CFRp-3D values without and with hydrostatic offset correction and the measured Doppler CFR values: r = 0.57, p = 0.01, and r = 0.89, p < 0.0001, respectively. (C,D) Bland-Altman analysis of the agreement between the calculated CFRp-3D values without and with hydrostatic offset correction and the measured Doppler CFR values.

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  Figure 5. Correlation and agreement between the results of the ComboWire-based RRR measurements (RRRDoppler) and the calculated RRRp-3D values with the correction for hydrostatic offset. (A) The calculated microvascular resistance reserve RRRp-3D corrected to the hydrostatic pressure error demonstrated a good correlation with the measured MRRDoppler values (r = 0.83, p < 0.0001). (B) The Bland-Altman analysis showed the mean differences between the Doppler-measured and the calculated RRRp-3D values with hydrostatic offset correction to be −0.03 (±1.96 SD: 0.71, −0.78).

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  Figure 6. Clustered multiple variable graphs of resting Pd/Pa, FFR, and CFRp-3D without and with hydrostatic pressure correction. In both the resting and the hyperemic (FFR) state (A,B), the correction of the hydrostatic offset resulted in differences in consequent directions between the uncorrected and corrected values in the main coronary branches. The correction significantly increased the values in the LAD, while in the LC and the RCA the values decreased. Much greater differences in the same direction can be observed for the CFRs, especially in the range of the higher values (C).