Evaluation of Left Ventricular Function in Atrial Fibrillation by Means of Ejection Time versus Preceding Cycle Length
The previous observations from our laboratory on correlations between left ventricular ejection time (ET) and preceding cycle length in patients with atrial fibrillation showed that the correlation coefficients were lower in patients with dilated cardiomyopathy than in patients with lone atrial fibrillation. These findings were considered to be related to decreased left ventricular function. To elucidate this assumption, experimental studies were done by using 10 open-chest dogs. After inducing atrial fibrillation by aconitine, various left ventricular contraction states were produced by administration of β-blockade or isoproterenol, and ET, preceding RR interval, stroke volume (SV) and left ventricular dp/dt were measured at each state. The results were followings : 1) The relationship between ET and SV was found to be significantly linear, and had an over-all correlation of r=0.91 despite severity of left ventricular contraction states. 2) The relationship between ET and preceding RR interval showed a positive correlation, and the coefficient became lower as left ventricular function decreased. Therefore, this method proved to be clinically useful to assess the left ventricular contraction state by non-invasive measurements of ET and preceding RR interval from carotid pulse tracing in patients with atrial fibrillation.
