Yamaguchi H, Takaki M, Ito H, Tachibana H, Lee S, Suga H
Department of Physiology II, Okayama University Medical School, Japan.
Jpn J Physiol. 1997 Feb;47(1):101-10. doi: 10.2170/jjphysiol.47.101.
How left ventricular (LV) contractility relates to irregular RR intervals during atrial fibrillation (AF) is still unclear. We investigated the relationship between the LV contractility (Emax) of individual beats and their preceding RR intervals during AF in isovolumic contractions is excised cross-circulated canine hearts, and additionally in ejecting contractions in in situ canine hearts. Atrial high-frequency electrical stimulation induced AF. We recorded a LV electrocardiogram, volume and pressure, and calculated the Emax of every arrhythmic beat. Multiple linear regression analysis between Emax and the six preceding RR intervals of all arrhythmic beats during 1 min AF showed the preceding RR interval (RR1) and the pre-preceding interval (RR2) to be the predominant predictors of Emax. The Emax-RR1/RR2 scattergram was closely fitted by a linear regression line. We found Emax at RR1/RR2 = 1 on the regression line to be virtually identical with both mean Emax during AF and stable Emax obtained during irregular atrial pacing at the same intervals as the mean RR interval during AF. These results newly indicate that the pressure-interval relationship predominantly characterizes LV irregular beat contractilities and their mean level during AF.
左心室（LV）收缩力与心房颤动（AF）期间RR间期不规则之间的关系仍不清楚。我们研究了在离体交叉循环犬心脏等容收缩期间以及在体犬心脏射血收缩期间，房颤时单个心动周期的左心室收缩力（Emax）与其前RR间期之间的关系。心房高频电刺激诱发房颤。我们记录了左心室心电图、容积和压力，并计算了每个心律失常心动周期的Emax。对房颤1分钟内所有心律失常心动周期的Emax与其前六个RR间期进行多元线性回归分析，结果显示前RR间期（RR1）和前前间期（RR2）是Emax的主要预测因素。Emax-RR1/RR2散点图与线性回归线拟合紧密。我们发现在回归线上RR1/RR2 = 1时的Emax与房颤期间的平均Emax以及在与房颤期间平均RR间期相同间隔的不规则心房起搏期间获得的稳定Emax几乎相同。这些结果首次表明，压力-间期关系主要表征了房颤期间左心室不规则搏动收缩力及其平均水平。
