posted on 2017-11-23, 14:24authored bySharon H. Man, O Vito, Nawshin Dastagir, JA Burridge, TP Almeida, Shoaib Siddiqui, Gavin S. Chu, Subrahmanya S. Varanasi, Shui H. Chin, Fernando S. Schlindwein, William B. Nicolson, R Chelliah, RK Pathmanathan, D Chin, G. Andre Ng
BACKGROUND: Mechanical characteristics of the left ventricle (LV) may be encoded in
cardiac acoustic signatures within low frequency ranges.
PURPOSE: We aimed to characterise i) acoustic features in the frequency domain in
subjects with normal LV function (Group 1) and patients with heart failure with reduced
ejection fraction (HFREF) indicated for cardiac resynchronisation therapy (CRT, Group
2) and ii) their relationship with aortic velocity time integral (VTI) with respect to signal
to noise ratio (SNR) during atrio-ventricular (AV) optimisation of CRT.
METHOD: 15-seconds segments of heart sounds obtained from electronic (e-) stethoscope
recordings of subjects in Group 1 (N¼21), Group 2 (N¼28), and 4 subjects
undergoing AV optimization of CRT were subjected to a novel signal processing
method to detect S1 and S2 sounds envelopes and extract frequency-domain acoustic
features from the detected envelopes. During AV optimization of CRT (pacing at
90bpm), aortic VTI and EA duration were measured with Doppler on echocardiography
from a range of paced AV delays (PAVD). The optimal PAVD was found at the
highest aortic VTI with the best EA duration and pattern for LV filling. The SNR of the
acoustic features were calculated by dividing the range of signals across all the tested
PAVD by the average size of the standard error of mean (SEM) (the noise) at each
PAVD.
RESULTS: 1) Two frequency-domain features extracted from the S1 envelopes
(AV_S1_B and AV_S1_C) were higher in Group 1 compared to Group 2 (fig. 1). No difference
was found in the same features extracted from the S2 envelopes (AV_S2_B
and AV_S2_C) between the 2 groups. 2) During AV optimization of CRT, AV_S1_C
correlated with aortic VTI in subjects with high SNR (e.g. SNR¼7.8: N¼10, r¼0.67,
p¼0.03, 2-tailed) but not in those with low SNR (e.g. SNR¼3.9: N¼7, r¼-0.322,
p¼0.48). 3) In the subject with the highest SNR (7.8), the PAVD at the highest value of
AV_S1_C coincides with the optimal PAVD derived from echocardiography (fig. 2).
CONCLUSION: e-Cardiac acoustics offer a potential novel method to diagnose HFREF
and optimize AVD in CRT. Future studies to confirm the current findings and improve
the SNR of this method are needed for clinical utility.
History
Citation
EP Europace, 2017, 19 (suppl_3), pp. iii384-iii385
Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Engineering
Version
AM (Accepted Manuscript)
Published in
EP Europace
Publisher
Oxford University Press for European Society of Cardiology (ESC), European Heart Rhythm Association
The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.