Calculating Intraventricular Pressure Difference Using a Multi-Beat Spatiotemporal Reconstruction of Color M-Mode Echocardiography

This work aims to provide a methodology to improve the analysis of color-M-Mode (CMM) echocardiograms, as used to assess cardiac function. Specifically, we presented a methodology for the combined analysis of multiple heartbeat cycles and improve the accuracy of intraventricular pressure difference (IVPD) calculation. CMM sweep speed and heartbeat variations impact the accuracy of IVPD calculation. Proper orthogonal decomposition (POD) is used to decompose and reconstruct a representative CMM scan from multiple heartbeats, with reduced noise and improved resolution. For three demonstration subjects, at least 9 beats were recorded at sweep speeds of 25, 50, 75, 100, and 150 mm/s. For all subjects, the beats from the 25 mm/s group resulted in low IVPD (median values: 1.93, 1.94 and 3.15 mmHg) compared to the 150 mm/s group (median values: 3.67, 3.98 and 5.18 mmHg). Reconstructed heartbeats for these subjects returned IVPD of 4.74, 3.23, and 5.14 mmHg. These results demonstrate the strong dependence of IVPD on the temporal resolution and that the proposed reconstruction method can return more accurate IVPDs for low resolution CMMs. This new method was applied to 5 clinical cohorts (3 normals, 1 restrictive, and 1 hypertrophied) and returned increased median IVPD from 2.93–4.41 mmHg for Normal 1, 2.14–3.30 mmHg for Normal 2, 1.84–3.64 mmHg for Normal 3, 2.28–3.00 mmHg for restrictive and 1.56–1.69 mmHg for hypertrophied. Our results show that beat-to-beat variations and temporal resolution affect the IVPD. Our new method rectifies low resolutions and beat-to-beat variability of the CMM data and allows for more accurate IVPD measurement independent of scanner acquisition settings and beat variations.