CENTRIFUGAL-FLOW LVAD INFLOW CANNULA POSITION: PREOPERATIVE INFLUENCES AND POSTOPERATIVE OUTCOMES

Background: We previously demonstrated better inflow cannula (IFC) position and reduced pump thrombosis with a centrifugal-flow LVAD (CF-LVAD) compared to an axial-flow device. We hypothesized that implant technique and patient anatomy would affect CF-LVAD IFC positioning and that malposition would impact LV unloading and outcomes. Methods: Pre- and postoperative computed tomography (CT) scans were reviewed for patients with six-month follow-up. Malposition was quantified using angular deviation from an ideal line in two planes. IFC position was compared between conventional sternotomy (CS) and lateral thoracotomy-hemisternotomy (LTHS). The influence of LV end-diastolic dimension (LVEDD), body mass index (BMI), and CT-derived anatomy was determined. LV unloading was assessed by LVAD flow index (FI) and pre- to post-LVAD decrement in mitral regurgitation (MR) and LVEDD. Outcome measures were pump thrombus or stroke (PT/eCVA); 30-day and total heart failure-related readmissions (HFRAs); and survival free of surgery for LVAD dysfunction. Results: One hundred fourteen patients met criteria. Total malposition magnitude was higher for CS than LTHS (p=0.04). Midline-LV apex distance predicted lateral-plane malposition (p=0.04), while apex-LVOT angle predicted both anterior- (p=0.01) and lateral-plane (p=0.04) malposition. Lateral-plane malposition predicted decreased LVAD FI at three (p=0.03) and six (p=0.01) months. Total malposition magnitude predicted increased 30-day HFRAs (p=0.04), while lateral-plane malposition predicted more overall HFRAs (p=0.01). Malposition was not associated with PT/eCVA, changes in MR or LVEDD, or survival free of surgical revision. Conclusions: Patient anatomy and surgical technique were associated with CF-LVAD IFC malposition. In turn, malposition was associated with increased readmissions and decreased LVAD FI.

Pump position and thrombosis in ventricular assist devices: Correlation of radiographs and CT data

Malpositioning of left ventricular assist devices (LVAD) is a risk factor for thrombosis, but its identification from clinical imaging remains challenging. X-rays and CT scans were analyzed and parameters identified that correlated to pump thrombosis. Retrospective imaging data of patients ( n = 115) with HeartmateII (HMII) or HVAD were analyzed in two groups (pump-thrombosis PT, n = 15 vs matched control group NT, n = 15) using routine X-rays and CT scans. In CT, directional deviations of the inflow cannula in three-chamber and two-chamber view (α and β angles) were identified. In HVAD PT frontal radiographs showed reduced pump body area and smaller minor axis (PT 41.3 ± 4.8 mm vs NT 34.9 ± 6.0 mm, p = 0.026), and in the lateral radiographs the visibility of the inflow cannula served as a predictive parameter for PT. In HMII patients, no parameters were associated with PT. The angle α differed significantly (NT −1.2 ± 7.5°, PT −22.0 ± 4.7°, p = 0.006) in HVAD patients. Further, correlations of x-ray parameters with CT angles α and β showed that radiographs can be used to identify malpositioned pumps. Well-aligned inflow cannula positions are essential. HVAD patients with a posterior rotation of the inflow cannula have a higher risk of pump thrombosis. This risk can reliably be identified from routine radiographs.

Understanding the influence of left ventricular assist device inflow cannula alignment and the risk of intraventricular thrombosis

Background Adverse neurological events associated with left ventricular assist devices (LVADs) have been suspected to be related to thrombosis. This study aimed to understand the risks of thrombosis with variations in the implanted device orientation. A severely dilated pulsatile patient-specific left ventricle, modelled with computational fluid dynamics, was utilised to identify the risk of thrombosis for five cannulation angles. With respect to the inflow cannula axis directed towards the mitral valve, the other angles were 25° and 20° towards the septum and 20° and 30° towards the free wall. Results Inflow cannula angulation towards the free wall resulted in longer blood residence time within the ventricle, slower ventricular washout and reduced pulsatility indices along the septal wall. Based on the model, the ideal inflow cannula alignment to reduce the risk of thrombosis was angulation towards the mitral valve and up to parallel to the septum, avoiding the premature clearance of incoming blood. Conclusions This study indicates the potential effects of inflow cannulation angles and may guide optimised implantation configurations; however, the ideal approach will be influenced by other patient factors and is suspected to change over the course of support.