Factors influencing the ejection fraction and the mean rate of circumferential fibre shortening during atrial fibrillation in man

Sixty-six cardiac cycles in 10 patients with valvular heart disease and depressed left ventricular performance who had atrial fibrillation were analysed by measurement of arterial pressure, R-R interval and the cineangiographically derived end-diastolic volume, ejection fraction, and mean rate of circumferential fibre shortening at the minor left ventricular equator. For each beat the independent influence on left ventricular performance of variations in end-diastolic volume, aortic diastolic pressure and abrupt charges in cycle length was assessed. The most prominent influence on beat-to-beat alterations in left ventricular performance in these patients appeared to be mediated through the Frank-Starling mechanism.