## 3 Results
CF-LVAD support reduced the left atrial and ventricular volumes, whereas right atrial volumes and right ventricular end-diastolic volumes increased under CF-LVAD support for all the simulated cases. The waveforms for the left and right atrial and ventricular pressure signals for the simulated normal SR and AF with unimodal RR interval distributions were also reported in the left and right ventricular volumes. Figure 3: **(a)** Left atrial (LA) volumes for heart failure during normal sinus rhythm (SR) and atrial fibrillation (AF) with unimodal and bimodal RR interval distributions; **(b)** LA volumes for CF-LVAD support during normal SR and AF with unimodal and bimodal RR interval distributions; **(c)** right atrial (RA) volumes for heart failure during normal SR and AF with unimodal and bimodal RR interval distributions; **(d)** RA volumes for CF-LVAD support during normal SR and AF with unimodal and bimodal RR interval distributions; **(e)** left ventricular (LV) volumes for heart failure during normal SR and AF with unimodal and bimodal RR interval distributions; **(f)** LV volumes for CF-LVAD support during normal SR and AF with unimodal and bimodal RR interval distributions; **(g)** right ventricular (RV) volumes for heart failure during normal SR and AF with unimodal and bimodal RR interval distributions; **(h)** RV volumes for CF-LVAD support during normal SR and AF with unimodal and bimodal RR interval distributions. and AF with unimodal and bimodal RR interval distributions for heart failure and CF-LVAD support over a 6 s period are given in Figure 4.  
Left atrial pressure during AF with bimodal RR interval distribution remained relatively low for heart failure. CF-LVAD support reduced the overall left atrial pressures for all the simulated cases, whereas right atrial pressures increased under CF-LVAD support. Left ventricular peak pressure was relatively high over some of the cardiac cycles during AF with bimodal RR interval distribution for heart failure, because of the simulated relation between left ventricular systolic  
Figure 4: (**a**) Left atrial (LA) pressures for heart failure during normal sinus rhythm (SR) and atrial fibrillation (AF) with unimodal and bimodal RR interval distributions; (**b**) LA pressures for CF-LVAD support during normal SR and AF with unimodal and bimodal RR interval distributions; (**c**) right atrial (RA) pressures for heart failure during normal SR and AF with unimodal and bimodal RR interval distributions; (**d**) RA pressures for CF-LVAD support during normal SR and AF with unimodal and bimodal RR interval distributions; (**e**) left ventricular (LV) pressures for heart failure during normal SR and AF with unimodal and bimodal RR interval distributions; (**f**) LV pressures for CF-LVAD support during normal SR and AF with unimodal and bimodal RR interval distributions; (**g**) right ventricular (RV) pressures for heart failure during normal SR and AF with unimodal and bimodal RR interval distributions; (**h**) RV pressures for CF-LVAD support during normal SR and AF with unimodal and bimodal RR interval distributions. and pre-preceding cardiac cycle duration ratio. CF-LVAD support reduced the left ventricular pressures for all the simulated cases. Right ventricular pressures slightly decreased under CF-LVAD support. The waveforms for the aortic and pulmonary arterial pressure signals and left middle cerebral arterial blood flow rate signal for the simulated normal SR and AF with unimodal and bimodal RR interval distributions for heart failure and CF-LVAD support over a 6 s period have been given in Figure 5.  
Amplitude of the aortic pressure signal during AF with bimodal RR interval distribution was higher with respect to amplitudes of the aortic pressure signals for the other cases. CF-LVAD support reduced the systolic aortic pressure for all the cases while increasing the diastolic pressure. Moreover, amplitudes of the aortic pressure signals were similar under CF-LVAD support for all the cases.