title: Non-invasive assessment of cardiac contractility on a weighing scale.
abstract: Myocardial contractility, the intrinsic ability of the heart muscle to produce force, has been difficult to quantify non-invasively. Pre-ejection-period (PEP), the time the ventricles spend in isovolumetric contraction, is widely accepted as a way to measure contractility. This work presents a way by which the ballistocardiogram - a readily accessible non-invasive cardiovascular signal - can be used in tandem with the electrocardiogram to obtain a parameter highly correlated to PEP and thus to myocardial contractility. This parameter is the delay from the electrocardiogram R-wave to the peak (the J-wave) of the ballistocardiogram. In this work, we showed that this delay, the RJ interval, was correlated to PEP (r(2) = 0.75) for 709 heartbeats across 4 subjects, with a slope of 1.11, and a y-intercept of 151 ms. This suggests that the RJ interval can be used in place of the PEP for a reliable, practical, and non-invasive assessment of myocardial contractility.
authors: Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
authors: Mozziyar
authors: M
authors: Etemadi
authors: Omer T
authors: OT
authors: Inan
authors: Richard M
authors: RM
authors: Wiard
authors: Gregory T A
authors: GT
authors: Kovacs
authors: Laurent
authors: L
authors: Giovangrandi
mesh_terms: D001450:Ballistocardiography / Q000379:methods*; D001837:Body Weights and Measures / Q000379:methods*; D002307:Cardiography, Impedance; D004562:Electrocardiography; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors