Conversion of extracorporeal membrane oxygenation to non-pulsatile left ventricular assist device. Is it out-of-date for non-pulsatile LVAD?

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) provides an immediate support for acute deterioration of hemodynamic and pulmonary status, but what is the best decision for these critical patients? Biventricular assist device (BVAD) or left ventricular assist device (LVAD)? We proposed a protocol of step-by-step conversion from ECMO to LVAD after assurance of the reversibility of right ventricle and pulmonary function. METHODS: After femoral venoarterial ECMO was inserted for the critical patients, the left atrial drainage was added to the ECMO firstly and the femoral arterial inflow was shifted to the ascending aorta for preventing possible peripheral vascular complications. Temporary clamp of right heart drainage was tried to test right heart function 24 to 48 hours later. The sweep gas flow of oxygenator could be reduced gradually to test the pulmonary function. Therefore, the right heart drain and the oxygenator could be withdrawn to become a non-pulsatile LVAD or shift to pneumatic LVAD directly. There were four clinical experiences with successful conversion without temporary right ventricular assist device. RESULTS: All of them were able to convert their ECMO to LVAD smoothly in 8.0+/-2.5 days. Three of them were shifted to non-pulsatile LVAD, and one was converted to HeartMate. All but one could be weaned from the ventilator. No BVAD was needed in these patients. Due to the shortage of donor hearts, only one had the chance to undergo heart transplantation. CONCLUSIONS: The protocol did provide a good guideline for decision-making for those under ECMO support necessitating bridge to transplantation.     

More than 20 years’ experience of left ventricular assist device implantation at a non-transplant Centre

Objectives. Over recent decades implantable left ventricular assist devices (LVAD) have increased the possibility of improved survival in patients with advanced heart failure who also benefit from a better quality of life. The aim of this retrospective survey was to review the clinical results of LVAD implantation at a low-volume non-transplant centre (Linköping, Sweden) between 1993 and 2016. Our aim was also to assess the mortality and morbidity rates associated with implantation of three LVAD versions at our centre, and to compare our results with those from transplant centres. Design. A retrospective cohort study was performed examining the medical records of patients who had a HeartMate^® (HMI, HMII, HMIII) LVAD implanted as a bridge to heart transplantation (BTT) or as destination therapy (DT) at the University Hospital, Linköping. Results. Our main finding was a survival to heart transplantation rate of 82% among our BTT LVAD patients. The most common adverse event among our patients was infection. A higher frequency of temporary dialysis was seen in the HMII group compared to the HMI group, and the frequency of right ventricular failure was higher in our HMII material. Conclusions. Our data suggests that patients requiring long-term LVAD support can safely have their device implanted and cared for at a non-transplant centre.     

Effect of left ventricular assist device implantation on right ventricular function: Assessment based on right ventricular pressure–volume curves

Right ventricular (RV) failure is significantly associated with morbidity and mortality after left ventricular assist device (LVAD) implantation. However, it remains unclear whether LVAD implantation could worsen RV function. Therefore, we aimed to investigate the effect of LVAD implantation on RV function by comparing RV energetics derived from the RV pressure–volume curve between before and after LVAD implantation. This exploratory observational study was performed between September 2016 and January 2018 at a national center in Japan. Twenty-two patients who underwent LVAD implantation were included in the analysis. We measured RV energetics parameters: RV stroke work index (RVSWI), which was calculated by integrating the area within the RV pressure–volume curve; RV minute work index (RVMWI), which was calculated as RVSWI × heart rate; and right ventriculo–arterial coupling, which was estimated as RV stroke volume/RV end-systolic volume. We compared RV energetics between before and after LVAD implantation. Although RVSWI was similar [424.4 mm Hg · mL/m² (269.5-510.3) vs. 379.9 mm Hg · mL/m² (313.1-608.8), P = 0.485], RVMWI was significantly higher after LVAD implantation [29 834.1 mm Hg · mL/m²/min (18 272.2-36 357.1) vs. 38 544.8 mm Hg · mL/m²/min (29 016.0-57 282.8), P = 0.001], corresponding to a significantly higher cardiac index [2.0 L/min/m² (1.4-2.2) vs. 3.7 L/min/m² (3.3-4.1), P < 0.001] to match LVAD flow. Right ventriculo–arterial coupling was significantly higher after LVAD implantation [0.360 (0.224-0.506) vs. 0.480 (0.343-0.669), P = 0.025], suggesting that the efficiency of RV performance improved. In conclusion, higher RVMWI with higher cardiac index to match LVAD flow and improved efficiency of RV performance indicate that LVAD implantation might not worsen RV function.     

What is the optimal anticoagulation in patients with a left ventricular assist device?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether there is an optimal antithrombotic management for patients supported with axial-flow left ventricular assist devices (LVADs). Altogether, more than 758 papers were found using the reported search, of which 17 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. These included seven prospective and three retrospective cohort studies with a total of 538 patients with axial-flow left ventricular assist device (LVAD) (HeartMate II, Jarvik 2000, INCOR, Thoratec assist device) implanted across the world as destination therapy or bridge to transplantation. We conclude that there is a substantial alteration of the prothrombotic profile in patients with axial-flow LVADs. These abnormalities appeared to be reversible with the removal of the device and are likely to be responsible for the high incidence of non-surgical bleeding episodes reported. Warfarin seems to offer a lower thromboembolic risk compared with unfractioned heparin or low molecular weight heparin. There are reports that suggest that managing axial-flow LVAD without anticoagulation, after major bleeding complications, is possible but in all probability, these papers are subject to publication bias as poor outcomes are unlikely to have been reported. All patients with axial-flow LVAD, showed severely impaired platelet function at point of care tests. The use of warfarin (INR target 2.5), in association with aspirin at 100?mg/day, or with point-of-care tests titrated antiplatelet therapy to inhibit 70%, seems to have the best bleeding-thrombosis, and in many cases a very small dose of aspirin of 25?mg twice a day and a dose of clopidogrel of 35?mg/day, were sufficient to achieve a reduction of the maximum aggregation to less than 30%. Finally, we would like to emphasize that such recommendations are addressed only to patients with axial-flow LVAD.     

Does pretransplant left ventricular assist device therapy improve results after heart transplantation in patients with elevated pulmonary vascular resistance?

Objective: Pulmonary hypertension (PH), defined as a pulmonary vascular resistance (PVR) >2.5 Wood units (WU) and (or) a transpulmonary gradient (TPG) >12 mmHg, is an established risk factor for mortality in heart transplantation. Elevated PVR in heart transplant candidates can be reduced using a left ventricular assist device (LVAD), and LVAD is proposed to be the treatment of choice for candidates with PH. We analyzed the effect on PVR of pretransplant LVAD therapy in patients with PH and compared posttransplant outcome with matched controls. Long-term survival was compared between heart transplant recipients with mild, moderate or severe PH and patients with no PH. Methods: Heart transplant recipients 1988–2007 (n = 405) were reviewed and divided into two groups with respect to pretransplant PVR: <2.5 WU (n = 148) and >2.5 WU (n = 158). From the group with PH, patients subjected to pretransplant LVAD therapy (n = 11) were analyzed with respect to PVR at implant and at transplant and, with respect to outcome, compared to matched historical controls (n = 22). Patients with PH without LVAD treatment (n = 147) were stratified into three subgroups: mild, moderate and severe PH and survival according to Kaplan–Meier was analyzed and compared to patients with no PH. Results: LVAD therapy reduced PVR from 4.3 ± 1.6 to 2.0 ± 0.6 WU, p < 0.05. Three cases of perioperative heart failure required mechanical support whereas one control patient developed perioperative right heart failure requiring mechanical support. The incidence of other perioperative complications was comparable between groups. There was no difference in survival between LVAD patients and controls, 30-day survival was 82% and 91%, respectively and 4-year survival was 64% and 82%, respectively. Conclusions: Pretransplant LVAD therapy reduces an elevated PVR in heart transplant recipients, but there was no statistically significant difference in posttransplant survival in patients with PH with, or without LVAD therapy. The study revealed no differences in survival in patients regardless of the severity of the PH.     

Insertion of a left ventricular assist device in patients without thorough transplant evaluations: a worthwhile risk?

OBJECTIVES: Patients in acute cardiogenic shock may require placement of left ventricular assist devices before undergoing standard pretransplant evaluations. This practice raises ethical and logistic concerns and has led us to investigate the short- and long-term outcomes for this patient population.Methods and results We examined our adult bridge-to-transplant left ventricular assist device population over a 6-year period to characterize those patients with acute cardiogenic shock who received left ventricular assist devices on an emergency basis (ie, placement of a device within 24 hours of being listed for cardiac transplantation). Outcomes before and after transplant were compared with those of candidates with nonemergency evaluations by Kaplan-Meier survival curves and the Fisher exact test where appropriate. Of the 115 patients who required left ventricular assist device support, 73 (63%) patients required emergency placement; 70% of these patients survived to transplant compared with 83% of those with nonurgent device implantation (not statistically significant). Posttransplant survival curves were similar for patients with emergency device placement and those with nonurgent placement (not statistically significant). Twenty-two patients having emergency device placement did not undergo heart transplantation because of multisystem organ failure (14), device support withdrawal from irreversible neurologic injury (4), device or technical problems (2), and left ventricular assist device explant due to myocardial recovery (2). CONCLUSIONS: At our institution, the majority of left ventricular assist devices are placed on an emergency basis. Few of these patients require discontinuation of device support due to undetected conditions during abbreviated preoperative evaluation. Survival before and after transplant is comparable with those of patients who undergo nonurgent left ventricular assist device placement or medical therapy.     

HLA sensitization in ventricular assist device recipients: does type of device make a difference?

BACKGROUND: We sought to (1) characterize the temporal pattern of T-cell panel reactive antibody during ventricular assist device support, (2) identify predictors of higher T-cell panel reactive antibody during ventricular assist device support, and (3) determine whether device type remained a predictor after accounting for nonrandom device selection. METHODS: Between December 1991 and August 2000, 239 patients received implantable ventricular assist devices, of whom 231 had T-cell panel reactive antibody measured. Panel reactive antibody was measured before implantation of the assist device, approximately 2 weeks after device implantation, irregularly thereafter depending on clinical events and length of support, and at transplantation. Longitudinal mixed modeling was used to characterize the temporal pattern of sensitization and its predictors during ventricular assist device support. To account for nonrandom factors in device selection when comparing HeartMate (Thermo Cardiosystems, Inc, Woburn, Mass) and Novacor (Baxter Healthcare Corp, Novacor Div, Oakland, Calif) devices, we propensity-matched patients according to baseline characteristics. RESULTS: T-cell panel reactive antibody increased rapidly after implantation of the ventricular assist device and then immediately began to decrease. Predictors of higher T-cell panel reactive antibody during support with the assist device were a shorter interval from device implantation to T-cell panel reactive antibody measurement (P <.0001), female sex (P =.0004), younger age (P =.01), higher T-cell panel reactive antibody before device implantation (P =.03), more perioperative red blood cell transfusions (P =.006), and an earlier date of device implantation (P =.001). In matched patients, device type was not a predictor of higher T-cell panel reactive antibody during ventricular assist device support (P =.8). CONCLUSIONS: HLA sensitization during ventricular assist device support is not constant but increases rapidly at implantation and then decreases. This temporal pattern of sensitization is influenced by patient factors and not by the type of device.