title: Estimation of left ventricular function using a novel acoustic-based device.
abstract: BACKGROUND
  We examined the feasibility of estimating left ventricular ejection fraction (LVEF) by a novel acoustic-based device [vibration response imaging (VRI); Deep Breeze].
  
  
  METHODS
  One hundred and forty-one subjects (117 patients and 24 healthy volunteers; age 55 ± 15 years, 82% men) were examined by both VRI and echocardiography. LVEF was determined by echocardiography (echo-LVEF) using the biplane Simpson's method. Low-frequency acoustic signals (10-70 Hz) were recorded by VRI from the left posterior thorax by a matrix of 36 microphones during 8 s of breath holding, and an electrocardiogram was recorded simultaneously. The acoustic signals were processed digitally, and an algorithm designed to estimate LVEF was developed (VRI-LVEF), based on a combination of multiple acoustic (systolic and diastolic acoustic signals, beat-to-beat variability of acoustic signals and propagation of acoustic signals throughout the matrix), electrocardiographic and clinical parameters.
  
  
  RESULTS
  Mean echo-LVEF was 51 ± 15% (range, 11-76%). Echo-LVEF was reduced (< 50%) in 55 subjects (39%) and severely reduced (< 35%) in 28 subjects (20%). VRI-LVEF calculated by a multivariate algorithm correlated significantly with echo-LVEF (R(2) = 0·59; P < 0·001). VRI-LVEF accurately predicted the presence of reduced (< 50%) or severely reduced (< 35%) echo-LVEF, with sensitivities of 84% and 82%, specificities of 86% and 91%, positive predictive values of 79% and 70% and negative predictive values of 89% and 95%, respectively.
  
  
  CONCLUSIONS
  LVEF can be estimated using a novel acoustic-based device. This device may assist in triage of patients according to LVEF prior to definitive assessment of LVEF by echocardiography.
authors.affiliation: Deep Breeze Ltd, Or Akiva, Israel.
authors.forename: Naira
authors.initials: N
authors.lastname: Radzievsky
authors.forename: Surik
authors.initials: S
authors.lastname: Papyan
authors.forename: Igal
authors.initials: I
authors.lastname: Kushnir
authors.forename: Merav
authors.initials: M
authors.lastname: Gat
authors.forename: Alon
authors.initials: A
authors.lastname: Kushnir
authors.forename: Alex
authors.initials: A
authors.lastname: Sagie
authors.forename: Yoram
authors.initials: Y
authors.lastname: Agmon
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D000328:Adult; D000368:Aged; D000465:Algorithms; D016022:Case-Control Studies; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006347:Heart Sounds / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010701:Phonocardiography / Q000379:methods; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D016277:Ventricular Function, Left / Q000502:physiology*; D014732:Vibration