Ventricular and Atrial Pressure-Volume Loops: Analysis of the Effects Induced by Right Centrifugal Pump Assistance

Abstract

ABSTRACTBackground and ObjectiveThe main indications for right ventricular assist device (RVAD) support are right heart failure after implantation of a left ventricular assist device (LVAD) or early graft failure following heart transplantation. About 30-40% of patients will need RVAD support after LVAD implantation. Pulmonary hypertension is also an indication for right heart assistance. Several types of RVAD generating pulsatile or continuous flow are available on the market. These assist devices can be connected to the cardiovascular system in different ways. We sought to analyse the effects induced by different RVAD connections when right ventricular elastance is modified using a numerical simulator. The analysis was based on the behaviour of both left and right ventricular and atrial loops in the pressure-volume plane.MethodsNew modules of the cardiovascular network and a right ventricular centrifugal pump were implemented in CARDIOSIM© software simulator platform. The numerical pump model generated continuous flow when connected in series or parallel to the right ventricle. When the RVAD was connected in series (parallel), the pump removed blood from the right ventricle (atrium) and ejected it into the pulmonary artery. In our study, we analysed the effects induced by RVAD support on left/right ventricular/atrial loops when right ventricular elastance slope (EesRIGHT) changed from 0.3 to 0.8 mmHg/ml with the pump connected either in series or parallel. The effect of low and high rotational pump speed was also addressed.ResultsPercentage changes up to 60% were observed for left ventricular pressure-volume area and external work during in-parallel RVAD support at 4000 rpm with EesRIGHT = 0.3mmHg/ml. The same pump setting and connection type led to percentage variation up to 20% for left ventricular ESV and up to 25% for left ventricular EDV with EesRIGHT = 0.3mmHg/ml. Again the same pump setting and connection generated up to 50% change in left atrial pressure-volume loop area (PVLAL-A) and only 3% change in right atrial pressure-volume loop area (PVLAR-A) when EesRIGHT = 0.3mmHg/ml. Percentage variation was lower when EesRIGHT was increased up to 0.8 mmHg/ml.ConclusionEarly recognition of right ventricular failure followed by aggressive treatment is desirable to achieve a more favourable outcome. RVAD support remains an option for advanced right ventricular failure although onset of major adverse events may preclude its use.