Durable Right Ventricular Assist Device HeartMate 3 Implant to the Right Atrium for Right Ventricular Failure After LVAD Implant

Right heart failure (RHF) following left ventricular assist device (LVAD) implantation is associated with significant morbidity and mortality; heart transplantation, continuous inotropic support, and right ventricular assist device (RVAD) implantation constitute potential therapeutic options. We previously described a HeartWare (HW) (Medtronic, Fridley, MN) implant technique at the right atrium with pump fixation to the right anterior chest wall to manage RHF aiming to support a failing right heart post-LVAD implantation. Because the specific type of pump is not available in the market any more, the only option for durable RVAD is that of HeartMate 3 (HM3). We herein describe a case of HM3 implant to the right atrium in a patient who developed acute RHF post-LVAD implantation and underwent subsequently successful heart transplantation. A 42 year old woman with a history of end-stage non-ischemic cardiomyopathy heart failure with reduced ejection fraction (body mass index = 23 kg/m2 and body surface area = 1.77 m2) underwent elective LVAD HM3 implantation, fulfilling our center's right ventricular function eligibility criteria for LVAD implantation.1 Postoperatively, she developed electrical storm, refractory to multiple external cardioversions, and appropriate antiarrhythmic drug administration, followed by acute RHF with hemodynamic instability and low flow LVAD alarms. Α temporary RVAD Centri-Mag (Abbott, Plymouth, MN) centrifugal pump was placed by reopening the previous sternotomy. Due to persistent severe right ventricular dysfunction and the unavailability of an immediate suitable heart donor, we decided to proceed with implantation of HM3 in the right side aiming to provide durable right ventricular support. After cardiopulmonary bypass (CPB) initiation the speed of the LVAD HM3 was dropped to 3,000 rpms. Four felt rings of the size of the device apical ring were attached together as a block with several interrupted prolene 3-0 stitches. The ring of the HM3 was secured to the right atrial free wall with multiple Ethibon pledgeted circumferential sutures with the interposition of the four felt rings to decrease the protrusion depth of the inflow cannula into the right atrial chamber (Figure 1). Then the atrial wall was cored with the coring knife of the device, and the pump was inserted and secured with the standard fashion. The outflow graft of the RVAD HM3 was connected to the main pulmonary artery in end-to-side fashion with 5-0 prolene suture making a smooth curve around the right ventricle. The device was wrapped with a Gore-Tex patch (GORETEX) membrane and secured with three prolene no. 2 sutures tied with 60° apart from each other. The sutures were passed around the third rib and the fourth rib at the right anterior chest wall after opening the pleural space as it was previously described for HW (Medtronic, Fridley, MN) implantation to the right atrium by Chamogeorgakis et al.2 The RVAD HM3 drive line was tunneled at the right subcostal area and connected to the controller of the device. We weaned the patient off cardiopulmonary bypass under transesophageal echocardiographic (TEE) guidance (Figure 2); the left and right VADs were adjusted within 30% difference of flow between the two devices. The RVAD outflow graft and drive line were wrapped with a GORETEX membrane (Flagstaff, AZ). The two heavy prolene sutures were tied underneath the right chest wall. Before sternum reapproximation, TEE confirmed that the RVAD inflow cannula oriented toward the tricuspid valve, away from the interatrial septum, to avoid suction events. The maximum depth of HM3 inflow cannula in the right atrium after interposition of felt rings was 1.8 cm as measured by echocardiogram. Postoperatively, the patient was kept on oral anticoagulation with warfarin and International Normalized Ratio (INR) target of 2.5–3.5. Additionally, during the immediate post-implant period there were few suction events-low flow alarms of the RVAD. They were attributed to volume depletion from excessive diuretic treatment in combination with bleeding and high RVAD speed. They were addressed by decreasing speed of the RVAD under echocardiographic guidance (ensuring safe distance of the inflow cannula from the interatrial septum) and lowering diuretic dose. The final setting of the RVAD was 4,200 rpms providing a calculated 2.8 L/min flow while the LVAD speed was set at 5,600 rpms with a flow 4.4 L/min. Furthermore, there were several ventricular tachycardia episodes postoperatively that were inconsequential for the patient because she was under biventricular support.Figure 1.: HM3 ring at the right atrial wall. HM3, HeartMate 3. HeartMate 3 RVAD ring sewn at the right atrial wallFigure 2.: Perioperative transesophageal echocardiograph: Right atrial inflow cannula of RVAD HM3. HM3, HeartMate 3; RVAD, right ventricular assist device. Right atrial inflow cannula of RVAD HeartMate3 shown in transesophageal echocardiographThree months later a suitable heart donor became available and our patient underwent a successful heart transplantation. During reoperation for heart transplantation, special care was taken to take down the anchoring stitches to the chest wall once the sternum was reopened to release the pump from its GORETEX "envelop" and avoid tearing of the right atrium. The RVAD outflow graft was easily mobilized after removing the Goretex membrane. The LVAD explant, recipient cardiectomy, and donor heart implant were carried out in a standard fashion. The patient had an uneventful recovery. Biventricular Support (BVS) with the use of two HM3 was first reported by Potapov et al.3 where the feasibility of insertion of HM3 pump as an RVAD was discussed. The International multicenter experience of BVS with HM3 ventricular assist systems, published by Lavee et al.4 demonstrated that the low incidence of thrombosis recorded with the use of the HM3 as an LVAD has been maintained in the RVAD configuration series. Only one case resulted in primary RVAD thrombosis, and this occurred in a patient in whom both pumps were used in a total artificial heart configuration.5 The surgical technique we are describing in the present article was previously reported by Chamogeorgakis et al.2 for BVS with HW HVAD as durable VAD for the right side. As we move forward in the field of mechanical circulatory support, we need to remind ourselves that the 1 year survival rates in biventricular failure have remained static across eras (2006−2012 vs. 2013−2016) at 56% vs. 55%, respectively.6 The described technique is promising with lower thrombotic risk because the device is suspended from the chest wall, remains at a safe distance from the interatrial septum, and avoids obstruction from the tricuspid subvalvular apparatus. The lower thrombotic risk may be extrapolated in lower morbidity and mortality on the waiting list for heart transplantation. Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) will not have more than a handful of these creative approaches to biventricular failure making difficult and unlikely the identification of independent predictors of favorable outcomes. In any case, total artificial heart constitutes another therapeutic strategy for patients with biventricular failure. Center expertise, device availability, cost, and outcomes are issues that will keep the discussions open.