Left Ventricular Relaxation Abnormality Is Detectable by Analysis of the Relaxation Time Constant in Patients With Atrial Fibrillation

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Left ventricular (LV) contractility is constantly changing during atrial fibrillation (AF), which is dependent on the force-interval relationships. However, no information has been available on LV relaxation in patients with both AF and impaired LV systolic function. LV pressure was measured with a catheter-tipped micromanometer and the time constant of isovolumic LV pressure decline (τ_<bf>) was calculated with best exponential fitting from more than 10 consecutive beats. Patients with AF (5 with mitral valvular disease, 6 with idiopathic dilated cardiomyopathy, and 1 with no underlying disease) were subdivided into 2 groups:group A, with ejection fraction(EF) <0.5 (n=7);and group B, with EF≥0.5 (n=5). Linear correlation coefficients (r) between τ and RR_2, RR_2/RR_1, LV peak systolic pressure (peak LVP) were calculated. Although τ did not show a discrepancy between the 2 groups, τ_<bf> correlated better with _RR_2/RR_1 only in the group A patients. The relation between τ and peak LVP showed a good correlation with a steep slope (R, Δτ/Δpeak LVP) only in the group A patients (accentuated afterload-dependence). R was significantly different between the 2 groups. Thus, a beat-to-beat analysis of τ may be a practical and feasible way for detecting LV relaxation abnormality in patients with AF.
社団法人日本循環器学会の論文
2001-06-20