QUANTIFICATION OF CARDIAC KINETIC ENERGY AND ITS CHANGES DURING TRANSMURAL MYOCARDIAL INFARCTION ASSESSED BY MULTI-DIMENSIONAL SEISMOCARDIOGRAPHY

Abstract

Objective: Seismocardiography (SCG) records cardiac and blood-induced motion transmitted to the chest surface as vibratory phenomena. Evidences demonstrate that acute myocardial ischemia (AMI) profoundly affects the SCG signals. Multidimensional SCG records cardiac vibrations in linear and rotational dimensions and scalar parameter of kinetic energies can be computed. We speculate that AMI and revascularization profoundly modify cardiac kinetic energy as recorded by SCG. Design and method: Under general anesthesia, 21 swines underwent 90 minutes myocardial ischemia induced by percutaneous subocclusion of proximal left anterior descending (LAD) coronary artery and subsequent revascularization. Invasive hemodynamic parameters were continuously recorded. SCG was recorded during the baseline (BSL); immediately and 80 min after LAD subocclusion (AMI t0; AMIt80, respectively); immediately and 60 min after LAD reperfusion (RE t0, RE t80, respectively). iK was automatically computed for each cardiac cycle (iK_CC) in linear (iK_Lin) and rotational (iK_Rot) dimensions. iK was calculated during systole and diastole (iK_Sys and (iK_Dia, respectively). Results: Compared to baseline, troponins increased from 13.0 [6.5; 21.3] ng/dL to 170.5 [102.5; 475.0] ng/dL and LVEF dropped from 65.0 ± 0.0% to 30.6 ± 5.7% at the end of revascularization (both p < 0.0001). In the linear dimension, iK_Lin-CC, iK_Lin-Sys, iK_Lin-Dia dropped by 43%, 52%, 53% respectively (p < 0.0001, p < 0.0001, p = 0.03, respectively) from baseline to the end of reperfusion. In the rotational dimension, iK_Rot-CC and iK_Rot-Sys dropped by 30% and 36% respectively (p = 0.0006, p < 0.0001), but iK_Rot-Dia did not change (p = 0.41). The figure below represents the evolution of waveforms of iK computed from the SCG signals during the experimental procedure, specifically during BSL, AMIt0, AMIt80, REt0, REt60. Linear (B) and rotational (C) iK drop at AMIt0 compared to BSL, remain below baseline values during the all duration of AMI and returns to normal level during reperfusion. The hemodynamic parameters, except the pulmonary artery pulse pressure, were significantly correlated with parameters of iK. Conclusions: Multidimensional SCG can detect changes in myocardial contractility during experimental AMI, providing information on the cardiac contractile status expressed in term of iK. This automatic system may empower health care providers and patients to remotely monitor cardiovascular status in the near future.