Using Smart Wearables to Monitor Cardiac Ejection ^†.

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Wearable Technology

Background:

• Cardiovascular health is vital but not routinely monitored outside clinical settings.
• Smart wearables utilize photoplethysmography (PPG) to measure pulse waves (PW) and heart rate.
• PPG signals offer potential for assessing cardiac parameters due to their link to blood ejection.

Purpose of the Study:

• To investigate the feasibility of monitoring left ventricular ejection time (LVET) and left ventricular contractility (LVC) using PPG signals from the wrist.
• To assess if smart wearables can accurately estimate these cardiac parameters.

Main Methods:

• Simulated PPG pulse waves under various cardiovascular conditions using a numerical model.
• Estimated LVET and LVC from the first and second derivatives of simulated PPG PWs.
• Compared estimated values against reference values from aortic root blood pressure PWs.

Main Results:

• Strong agreement was found between estimated and reference LVET values.
• Feasibility of assessing LVET from PPG signals, including those from smartwatches, was demonstrated.
• Correlations for LVC were less strong, indicating a need for further research for robust contractility assessment.

Conclusions:

• Smart wearables show feasibility for assessing LVET, enabling daily cardiovascular monitoring.
• Further research is needed to improve the robust assessment of left ventricular contractility using smart wearables.