TY - JOUR

T1 - Contraction-relaxation coupling mechanism characterization in the thermodynamic phase plane

T2 - Normal vs. impaired left ventricular ejection fraction

AU - Wu, Yue

AU - Yu, Yingbo

AU - Kovács, Sándor J.

PY - 2007/4

Y1 - 2007/4

N2 - Using simultaneous pressure-volume measurements obtained during cardiac catheterization, we employ the thermodynamic phase-plane (TPP) method to characterize global contraction-relaxation coupling (CRC) between normal and impaired left ventricular (LV) ejection fraction (LVEF) groups. The cardiac cycle inscribes a closed loop in the TPP defined by the coordinates "potential" power [V(dP/dt), ergs/s] and "kinetic" power [P(dV/dt), ergs/s]. The TPP-derived indexes κ and ρ define the chamber's contractile and CRC attributes, respectively. Data from 33 subjects dichotomized as normal control (n = 22, >50% LVEF) and impaired LVEF (n = 11, <50% LVEF) were analyzed. The results were as follows: κ = 3.0 ± 1.1 and ρ = -0.38 ± 0.21 for controls and κ = 5.4 ± 1.6 and ρ = - 1.14 ± 0.47 for the impaired LVEF group; κ and ρ are significantly higher for impaired LVEF than for control (P < 0.001 for both). As κ increased, ρ decreased (r = -0.69) for all subjects. Hence, ventricles with impaired LVEF are thermodynamically less efficient because they require more potential power per unit of delivered kinetic power than controls. We conclude that TPP-derived indexes of CRC facilitate assessment of chamber efficiency in thermodynamic terms and elucidate the dominant differentiating features in terms of CRC indexes.

AB - Using simultaneous pressure-volume measurements obtained during cardiac catheterization, we employ the thermodynamic phase-plane (TPP) method to characterize global contraction-relaxation coupling (CRC) between normal and impaired left ventricular (LV) ejection fraction (LVEF) groups. The cardiac cycle inscribes a closed loop in the TPP defined by the coordinates "potential" power [V(dP/dt), ergs/s] and "kinetic" power [P(dV/dt), ergs/s]. The TPP-derived indexes κ and ρ define the chamber's contractile and CRC attributes, respectively. Data from 33 subjects dichotomized as normal control (n = 22, >50% LVEF) and impaired LVEF (n = 11, <50% LVEF) were analyzed. The results were as follows: κ = 3.0 ± 1.1 and ρ = -0.38 ± 0.21 for controls and κ = 5.4 ± 1.6 and ρ = - 1.14 ± 0.47 for the impaired LVEF group; κ and ρ are significantly higher for impaired LVEF than for control (P < 0.001 for both). As κ increased, ρ decreased (r = -0.69) for all subjects. Hence, ventricles with impaired LVEF are thermodynamically less efficient because they require more potential power per unit of delivered kinetic power than controls. We conclude that TPP-derived indexes of CRC facilitate assessment of chamber efficiency in thermodynamic terms and elucidate the dominant differentiating features in terms of CRC indexes.

KW - Cardiac power

KW - Left ventricular function

KW - Mathematical modeling

UR - http://www.scopus.com/inward/record.url?scp=34147165698&partnerID=8YFLogxK

U2 - 10.1152/japplphysiol.00593.2006

DO - 10.1152/japplphysiol.00593.2006

M3 - Article

C2 - 17185496

AN - SCOPUS:34147165698

VL - 102

SP - 1367

EP - 1373

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

SN - 0161-7567

IS - 4

ER -