Artificial Intelligence Estimation of Carotid-Femoral Pulse Wave Velocity using Carotid Waveform

Figures

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  Figure 1. RMSE vs Iteration. The RMSE unit is m/sec. A total number of 1000 iteration is used to make sure that the ensemble of neural networks has converged. The 0.09 m/sec gap between the train and test sets shows that the model has an acceptable generalization capability.

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  Figure 2. Estimated vs Measured PWV: The correlation is 0.85. Both axes have units of m/sec. The total RMSE is 1.05 m/sec. We can observe that as PWV goes above 12 m/sec the error starts to increase. For smaller values this behavior is less pronounced.

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  Figure 3. PWV Bland-Altman. Both axes have units of m/sec. The limits of agreement are approximately ±2.07. We can again observe that larger values of PWV correspond to more error.

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  Figure 4. Estimated vs Measured PWV for BMI ≤ 30 and PWV < 15. Both axes have units of m/sec. Using the Artery Society guidelines for validation of non-invasive hemodynamic measurement devices, we observe that there is a strong agreement between our estimation of PWV and the recorded values.

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  Figure 5. PWV Bland-Altman for BMI ≤ 30 and PWV < 15. Both axes have units of m/sec. This plot shows that our PWV estimation would be graded as acceptable by the Artery Society.

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  Figure 6. Kaplan– Meier estimates of cardiovascular disease by tertiles of PWV index. The solid line represents 7.9 ≤ PWV. The solid dashed line represents 6.5 ≤ PWV ≤ 7.9. The dashed line represents PWV ≤ 6.5.

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  Figure 7. Kaplan– Meier estimates of cardiovascular disease by tertiles of estimated PWV index. The solid line represents 7.86 ≤ estimated PWV. The solid dashed line represents 6.67 ≤ estimated PWV ≤ 7.86. The dashed line represents estimated PWV ≤ 6.67.

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  Figure 8. PWV model Bland-Altman for tertiles. All axes have units of m/sec. The tertiles are coming from the Kaplan-Meier analysis of the original PWV values. The upper-left plot is the Bland-Altman for PWV ≤ 6.5. The upper-right plot is for 6.5 < PWV < 7.9. The lower-left plot is the Bland-Altman for 7.9 ≤ PWV. All three different tertiles show that the model presented in this paper have an acceptable performance.