Dr Bernhardt began by reminding the audience of the features of the Impella 5.0. This device is an established transaortic axial flow ventricular assist device capable of providing forward blood flow of up to 5 l/min. It was originally designed for femoral access, but axillary access is increasingly used, as it allows for mobilisation of the patient. Recently, a published meta-analysis of Impella 5.0 reported favourable survival outcomes and high rates of myocardial recovery in patients with cardiogenic shock.1 The clinical uses of the surgically implanted Impella 5.0 include haemodynamic support for cardiogenic shock, safer weaning from extracorporeal membrane oxygenation (ECMO) devices, bridge-to-bridge (pre-left ventricular assist device and pre-heart transplant), bridge-to-recovery (myocarditis and peripartum cardiomyopathy) and controlled post-cardiotomy (mitral/aortic valve surgery, coronary artery bypass graft [CABG]/off-pump CABG with ejection fraction <20%).
Impella 5.0 has CE approval in Europe for a maximum 10 days of support. However, >70% of patients at Dr Bernhardt’s hospital require Impella 5.0 support for >10 days. Potential problems associated with longer duration of Impella 5.0 support include in-growth of the pigtail catheter, pump thrombosis and arterial embolisation, due to the presence of a repositioning sheath in the axillary artery.
The Impella 5.5 was developed to address both the need for a longer duration of support and to avoid the complications associated with the Impella 5.0. It is designed to provide haemodynamic support for up to 30 days. Like the Impella 5.0, the Impella 5.5 device is an axial flow transaortic cardiac support device mounted on a 9 Fr steering catheter with a 21 Fr pump cannula. The pump itself is shorter and stiffer than the Impella 5.0. Other improved features in the Impella 5.5 include an optical aortic pressure sensor distal to the outflow of the device and no pigtail at the tip of the catheter (eliminating the risk for in-growth of the pigtail and reducing the risk of thromboembolism and stroke) and improved kink resistance of the cannula. Importantly, the device provides a higher maximum pump flow of up to 5.8 l/min. The device is designed for axillary insertion and the repositioning sheath does not extend into the artery. In addition, modification of the motor size (37% shorter motor housing and the outlet area) improves deliverability. Other modifications in the motor include a modified interior for long-term durability and low purge flows.
Dr Bernhardt mentioned that the first-in-man experience with the new Impella 5.5 in two critically ill patients was performed at his institution.2 His experience is that the device is easier to implant and reposition. Until April 2019, a total of 32 patients at five German hospitals received Impella 5.5, with a survival rate of 68%.
Dr Bernhardt presented the case of a 63-year-old man receiving Impella 5.5 for post-cardiotomy failure. He had undergone aortic valve replacement (AVR) with a biological valve about 10 years earlier. The replacement valve had deteriorated and had an aortic valve opening of 0.8 cm2. At presentation, the patient had a left ventricular ejection fraction (LVEF) of 26% and left ventricular end-diastolic diameter (LVEDD) of 68 mm. The patient underwent repeat AVR with a Perimount Magna ease valve of 23 mm. Due to the inability to wean him off the cardiopulmonary bypass machine, the surgical team placed an Impella 5.5. The patient was successfully extubated 4 hours after the surgery; he was fully mobile on postoperative day 1 and Impella 5.5 was weaned and explanted under anaesthesia on day 8. At discharge, the patient had an LVEF of 35% and LVEDD of 60 mm.
Dr Bernhardt also mentioned that his institution was the first in Europe to use the Impella Connect, a cloud-based, remote-monitoring platform. The Impella Connect enables hospital clinicians and staff, along with Abiomed’s clinical support team, to view the Automated Impella Controller screen (showing ventricular pressure and Impella alarms, if any) through a secure website, allowing them to track, review and share that information from any internet-capable phone, tablet or computer.
He highlighted the new heart allocation system in the US that prioritises patients supported by temporary mechanical circulatory support (TMCS) devices, such as ECMO, over those with durable, continuous-flow left ventricular assist devices, which may increase the number of patients bridged to transplant with TMCS.3 Furthermore, a recent study by Yin et al. showed that the survival is lowest among patients bridged to transplant with ECMO compared with durable left ventricular assist devices.4 Dr Bernhardt proposed that the Impella 5.5 device may have beneficial outcomes after transplantation compared to ECMO, and should be considered for the potential lower adverse events and mortality rates during short-term device therapy on the waiting list.5
In conclusion, the Impella 5.5 expands the spectrum of available short-term mechanical circulatory support devices. New technical design features, such as the absence of pigtail, helps minimise the risk of thrombus formation, and the optical pressure sensor aids in easy pump placement and monitoring. Early experience with Impella 5.5 in patients shows promising outcomes. Future direction includes the design of the long-term bridge-to-recovery Impella heart pumps.