Ventricular assist devices in transposition and failing systemic right ventricle: role of tricuspid valve replacement.

OBJECTIVES: Ventricular assist device (VAD) for systemic right ventricular (RV) failure patients post-atrial switch, for transposition of the great arteries (TGA), and those with congenitally corrected TGA has proven useful to reduce transpulmonary gradient and bridge-to-transplantation. The purpose of this study is to describe our experience of VAD in systemic RV failure and our move towards concomitant tricuspid valve replacement (TVR). METHODS: This is a single-centre retrospective study of consecutive adult patients receiving HeartWare VAD for systemic RV failure between 2010 and 2019. From 2017, concomitant TVR was performed routinely. Demographic, clinical variables and echocardiographic and haemodynamic measurements pre- and post-VAD implantation were recorded. Complications on support, heart transplantation and survival rates were described. RESULTS: Eighteen patients underwent VAD implantation. Moderate or severe systemic tricuspid regurgitation was present in 83.3% of patients, and subpulmonic left ventricular impairment in 88.9%. One-year survival was 72.2%. VAD implantation was technically feasible and successful in all but one. Post-VAD, transpulmonary gradient fell from 16 (15-22) to 10 (7-13) mmHg (P = 0.01). Patients with TVR (n = 6) also demonstrated a reduction in mean pulmonary and wedge pressures. Furthermore, subpulmonic left ventricular end-diastolic dimension (44.3 vs 39.6 mm; P = 0.03) and function improved in this group. After 1 year of support, 72.2% of patients were suitable for transplantation. CONCLUSIONS: VAD is an effective strategy as bridge-to-candidacy and bridge-to-transplantation in patients with end-stage systemic RV failure. Concomitant TVR at the time of implant is associated with better early haemodynamic and echocardiographic results post-VAD.

Validity of Hemodynamic Monitoring Using Inert Gas Rebreathing Method in Patients With Chronic Heart Failure and Those Implanted With a Left Ventricular Assist Device.

OBJECTIVE: The present study assessed agreement between resting cardiac output estimated by inert gas rebreathing (IGR) and thermodilution methods in patients with heart failure and those implanted with a left ventricular assist device (LVAD). METHODS AND RESULTS: Hemodynamic measurements were obtained in 42 patients, 22 with chronic heart failure and 20 with implanted continuous flow LVAD (34 males, aged 50 ± 11 years). Measurements were performed at rest using thermodilution and IGR methods. Cardiac output derived by thermodilution and IGR were not significantly different in LVAD (4.4 ± 0.9 L/min vs 4.7 ± 0.8 L/min, P = .27) or patients with heart failure (4.4 ± 1.4 L/min vs 4.5 ± 1.3 L/min, P = .75). There was a strong relationship between thermodilution and IGR cardiac index (r = 0.81, P = .001) and stroke volume index (r = 0.75, P = .001). Bland-Altman analysis showed acceptable limits of agreement for cardiac index derived by thermodilution and IGR, namely, the mean difference (lower and upper limits of agreement) for patients with heart failure -0.002 L/min/m2 (-0.65 to 0.66 L/min/m2), and -0.14 L/min/m2 (-0.78 to 0.49 L/min/m2) for patients with LVAD. CONCLUSIONS: IGR is a valid method for estimating cardiac output and should be used in clinical practice to complement the evaluation and management of chronic heart failure and patients with an LVAD.

Initial conservative management strategy of HeartWare left ventricular assist device thrombosis with intravenous heparin or bivalirudin.

INTRODUCTION AND OBJECTIVES: Pump thrombosis is a serious left ventricular assist device complication, though there are no guidelines regarding its treatment. The main aim of this study was to describe a strategy of intravenous anticoagulation as the initial treatment in these patients and then to compare intravenous heparin with bivalirudin. METHODS: All consecutive patients who received a HeartWare left ventricular assist device from July 2009 to March 2019 were retrospectively analysed. Patients developing a pump thrombosis were selected, and treatment, outcomes and complications were recorded. RESULTS: During this period of time (116 months), 220 patients underwent HeartWare left ventricular assist device implantation and 57 developed pump thrombosis, with an incidence rate of first pump thrombosis of 0.17 events per patient-year of support (incidence rate of all episodes of pump thrombosis: 0.30 events per patient-year of support). All the patients were initially treated medically, predominantly with either intravenous heparin (n = 26) or bivalirudin (n = 16). Patients treated with bivalirudin during the first pump thrombosis episode had less subsequent re-thrombosis episodes (18.7% vs 57.7%, p < 0.05). In addition, percentage time in therapeutic range was greater for bivalirudin compared with heparin (68.5% ± 16.9% vs 37.4% ± 31.0%, p < 0.01). During the first pump thrombosis episode, 26.3% of the patients needed surgery (left ventricular assist device exchange (n = 8), transplant (n = 6) or decommissioning (n = 1)). The overall survival at 1 year was 61.4%, and there was no significant difference in survival. CONCLUSION: Left ventricular assist device thrombosis is a serious life-threatening complication; hence, we propose an initial conservative management of pump thrombosis with enhanced intravenous anticoagulation with either intravenous heparin or bivalirudin, with surgery reserved for refractory cases.

Effect of Preoperative Tricuspid and/or Mitral Regurgitation on Development of Late Right-Sided Heart Failure After Insertion of the HeartWare Left Ventricular Assist Device.

Right-sided heart failure (RHF) after left ventricular assist device implantation is a significant cause of morbidity and mortality. Although multiple predictors of early RHF have been described, information on late RHF is scarce. The aim of this study was to identify predictors of late RHF in left ventricular assist device patients. A retrospective analysis of all adult patients who underwent HeartWare-ventricular assist device implantation as a bridge to transplantation in a single-centre was performed. Late RHF was defined as RHF requiring rehospitalization after 30 days of implantation. A total of 16 (10.3%) patients from 156 implantations developed late RHF. Median time to late RHF onset was 182.5 (interquartile range 105 to 618) days. Patients developing late RHF were older at surgery. A significantly higher rate of moderate or severe tricuspid regurgitation before implantation was found in patients presenting with late RHF (81.2% vs 33.5%; p <0.001). Several echocardiographic parameters at discharge postimplant, such as significant mitral regurgitation, demonstrated a strong association with late RHF. A multivariate Cox regression analysis revealed that significant preoperative tricuspid regurgitation was the strongest predictor of late RHF (hazard ratio 5.50, 95% confidence interval [1.34 to 22.58]; p = 0.02). Significant mitral regurgitation postimplantation and older age also significantly predicted late RHF. In conclusion, preoperative significant tricuspid regurgitation and mitral regurgitation after implantation predict the occurrence of late RHF.

Myocardial Recovery Strategy with Decommissioning for the HeartWare Left Ventricular Assist Device.

To manage myocardial recovery in patients with the HeartWare left ventricular assist device (HVAD), we describe a minimally invasive approach (decommissioning) that involves disconnecting the driveline and occluding the outflow tract through a small left thoracotomy incision, leaving the device in situ, in conjunction with optimal medical therapies and comprehensive assessment of left ventricular recovery. Nine patients (all male, 37 ± 12 years, all nonischemic dilated cardiomyopathy) had an HVAD implanted for 766 ± 343 days. When left ventricular function improved to mild impairment by echocardiography, patients underwent assessment at reduced flow (2578 ± 148 to 1822 ± 67 rpm) with documentation of compensated right heart hemodynamics and ejection fraction 52 ± 8%. Eight of nine patients underwent decommissioning, and 1 patient had a hybrid procedure of percutaneous occlusion of outflow graft and surgical division of driveline. Two patients died postoperatively at 413 days (sepsis) and 810 days (heart failure). In conclusion, in selected patients with nonischemic dilated cardiomyopathy, a prolonged period of HVAD support in conjunction with heart failure medications can lead to recovery of left ventricular function. Surgical decommissioning is then an option to remove these patients from support. These patients are, however, not cured and remain at risk for future deterioration in ventricular function and infections.

Four-year outcomes with third-generation centrifugal left ventricular assist devices in an era of restricted transplantation.

OBJECTIVES: Third-generation ventricular assist devices (VADs) are associated with improved outcomes, though in recent clinical trials bridge-to-transplant (BTT) rates are ∼30% at 6 months, so that transplantation can be used as a 'bail out' for serious complications. In the UK, there was a significant reduction in heart transplantation rates over the last decade, so that transplantation from VADs is much less frequent. The objective of this study was to determine outcomes and their predictors in this situation of low BTT rates, and as patients were exposed to long-term support, the incidence and outcomes of VAD thrombosis. METHODS: We analysed outcomes for 102 consecutive patients between 2009 and 2013 (mean age 47 ± 13; VentrAssist n = 6 and HeartWare n = 96). The median duration of support was 462 ± 426 days. RESULTS: Survival rates on the device were 75 and 66% at 1 and 2 years, respectively. Older age and more acute INTERMACS groups were significantly related to reduced survival within the first 90 days (P = 0.030 and 0.010, respectively). Poor preoperative right ventricular (RV) function had a negative effect on survival after 1 year (P = 0.009), though not earlier. VAD thrombosis (n = 24 HeartWare and n = 1 VentrAssist) occurred at 0.18 events per patient-year for HeartWare and 0.07 for VentrAssist devices at a median time of onset at 404 ± 281 days. There was no significant effect of VAD thrombosis on survival. Only 14 of 102 patients were transplanted at a median of 334 ± 347 days, and only 3 were transplanted within the first 6 months. CONCLUSIONS: Third-generation left ventricular assist device implants with a low rate of transplantation have similar survival to destination therapy, and are susceptible to long-term complications of VAD thrombosis and right heart failure.