LOAD-DEPENDENT PERIOD-DOUBLING BIFURCATIONS IN THE HEART OF THE ANESTHETIZED PIG

The onset of period-doubling behaviour in cardiac physiology is often associated with pathological states and an adverse prognosis. Changes in myocardial loading frequently accompany cardiac disease, and there is growing evidence that they may be important in the genesis of cardi ac arrhythmias. This study investigates the effect of changes in myoca rdial loading on period-doubling bifurcations of mechanical activity i n the heart of the anaesthetized pig. Changes in loading can both prod uce and abolish period-doubling bifurcations in the mechanical behavio ur of the heart. The dual effect of changes in loading may reflect the movement of the system around a bifurcation point.