Introduction:
The cardiovascular (CV) system produces low frequency, ‘infrasonic’, auditory vibrations during the cardiac cycle. Herein, we report the first-in-person validation of a novel earbud sensor to capture CV time intervals and the feasibility of non-invasive infrasonic hemodynography (IH) using the MindMics ® wireless earbuds for long term in-ear CV monitoring.
Methods:
Infrasonic waveforms were captured during cardiac catheterization (CC) among 5 study subjects wearing the IH ear-buds (Figure A) who underwent CC for the evaluation of coronary artery disease. Simultaneous IH and CC waveforms were acquired and time synchronized at 1000Hz sampling rate as time-series datasets. Each subject underwent echocardiography to identify aortic valve opening/closure (AVO/AVC) and left ventricular (LV) outflow tract flow measurements with hemodynamic waveforms during CC measuring LV ejection time (LVET). Validation of the IH waveform (in-ear acoustic pressure measured in Pascals) was compared to echocardiography (AVO/AVC) and hemodynamic waveforms (LVET) with concordance and Bland-Altman analysis, and with overlaid data visualizations to CV time intervals.
Results:
5 study subjects comprised 257 CV cycles with a total data set of >450,000 time-series data points. IH signals collected simultaneously with the pulsed wave Doppler demonstrated alignment with AVO/AVC (Figure B) and were synchronized to CC waveforms in the aorta (Figure C). A high correlation between LVET measured from IH and CC was observed (R=0.87, p<0.0001, Figure D), with a mean absolute error of 14.7ms and a bias of 7.2ms (Figure E) (mean±SEM of 342.3±2.1ms for CC and 349.5±2.1ms for IH).
Conclusions:
In a first-in-person study, we report high accuracy between IH, echocardiography, and CC hemodynamic waveforms to capture CV time intervals including CV performance measures. Further studies are underway to validate IH and the earbud sensor towards non-invasive hemodynamic monitoring.
Primary percutaneous coronary intervention (PCI) is now the recommended reperfusion technique for patients with acute ST-segment elevation myocardial infarction. However, despite early reperfusion in the majority of patients, PCI does not achieve effective myocardial reperfusion in a significant proportion of patients due to the prevalence of coronary microvascular obstruction. The amount of infarcted myocardium has been considered to be a reliable indicator of major adverse cardiovascular events and resultant adverse left ventricular remodeling. The purpose of this paper is to review the clinical benefits of supersaturated oxygen therapy following PCI for ST-segment elevation myocardial infarction.
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