title: Evaluation of regional work from ECG-gated SPECT images through solution of equations of continuity for fluids-mechanical cardiac work calculated using thin wall model.
abstract: Regional contraction work (RCW) of left ventricle (LV) was evaluated from cardiac perfusion images of ECG-gated single photon emission computed tomography (ECG-SPECT). The mechanical work was computed as a product of force and displaced distance. Force was determined from Laplace's law under a rectangle pressure. Deformation of wireframe representing LV was calculated from equations of continuity for two-dimensional fluids. Experiments were performed with homemade life-sized cardiac models. Total contraction work (TCW) and stroke work (SW) were 524.0 ± 166.1 mJ/beat and 709.8 ± 169.5 mJ/beat, respectively, in normal subjects (n = 23). Moderate correlation was seen between TCW and SW (y = -43.4 + 0.779 x, r = 0.815). The regional contraction amplitude (RCA), synchronous contraction index and RCW were 35.4 ± 3.5%, 95.4 ± 3.1% and 5.58 ± 0.97 mJ cm(-2)/beat in normal subjects, whereas those in patients with decreased ejection raction (EF) ≤ 30% (n = 6) were 19.6 ± 7.7%, 64.4 ± 32.2% and 2.58 ± 0.82 mJ cm(-2)/beat (p < 0.0001, Student's t-test). There was a poor correlation between RCW and RCA (y = 1.648 ± 0.116 x, r = 0.501) in normal subjects, suggesting that it might not be suitable to use RCA as an alternative to evaluate RCW.
authors.affiliation: Department of Radiological Technology, School of Health Sciences, Nagoya University, 1-1-20 Daiko-minami, Higashi-ku, Nagoya, Japan. maeda@met.nagoya-u.ac.jp
authors.forename: Hisatoshi
authors.initials: H
authors.lastname: Maeda
mesh_terms: D000328:Adult; D004562:Electrocardiography / Q000379:methods; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D013318:Stroke Volume / Q000502:physiology; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D016276:Ventricular Function / Q000502:physiology*; D014937:Work / Q000502:physiology*