Second heart sound splitting as an indicator of interventricular mechanical dyssynchrony using a novel splitting...

Area of Science:

• Cardiology
• Biomedical Engineering
• Signal Processing

Background:

• Second heart sound (S2) splitting, caused by asynchronous aortic (A2) and pulmonic (P2) valve closure, indicates ventricular timing differences.
• Accurate measurement of S2 splitting is challenging due to overlapping sounds and changing morphologies.
• Interventricular relaxation dyssynchrony (IRD) is a critical parameter in cardiac function assessment.

Purpose of the Study:

• To introduce and validate a novel S-transform amplitude ridge tracking (START) algorithm for estimating the S2 splitting interval.
• To investigate the relationship between S2 splitting and interventricular relaxation dyssynchrony (IRD).

Main Methods:

• Validation of the START algorithm using a simulated heart sound model with varying splitting intervals, amplitude ratios, and signal-to-noise ratios.
• Evaluation of the START algorithm in a porcine model with induced right ventricle (RV) and left ventricle (LV) delays.
• Quantification of IRD using invasive measurements of LV and RV pressure downslopes.

Main Results:

• The START algorithm demonstrated high accuracy in simulated data, with errors less than 5 ms across various conditions.
• In the porcine model, a significant decrease in mean S2 splitting interval (47 ms to 23 ms) correlated with reduced IRD (8 ms to -18 ms) as RV-LV delays changed.
• A strong significant correlation (p < .001) was found between S2 splitting interval and IRD in all experimental conditions.

Conclusions:

• The START algorithm provides an accurate method for assessing S2 splitting intervals.
• This novel algorithm shows promise as a valuable tool for non-invasively evaluating interventricular dyssynchrony.