Mary E. Keebler

PREVENtion of HeartMate II Pump Thrombosis Through Clinical Management: The PREVENT multi-center study

BACKGROUND Recommended structured clinical practices including implant technique, anti-coagulation strategy, and pump speed management (PREVENT [PREVENtion of HeartMate II Pump Thrombosis Through Clinical Management] recommendations) were developed to address risk of early (<3 months) pump thrombosis (PT) risk with HeartMate II (HMII; St. Jude Medical, Inc. [Thoratec Corporation], Pleasanton, CA). We prospectively assessed the HMII PT rate in the current era when participating centers adhered to the PREVENT recommendations. METHODS PREVENT was a prospective, multi-center, single-arm, non-randomized study of 300 patients implanted with HMII at 24 participating sites. Confirmed PT (any suspected PT confirmed visually and/or adjudicated by an independent assessor) was evaluated at 3 months (primary end-point) and at 6 months after implantation. RESULTS The population included 83% men (age 57 years ± 13), 78% destination therapy, and 83% Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) Profile 1-3. Primary end-point analysis showed a confirmed PT of 2.9% at 3 months and 4.8% at 6 months. Adherence to key recommendations included 78% to surgical recommendations, 95% to heparin bridging, and 79% to pump speeds ≥9,000 RPMs (92% >8,600 RPMs). Full adherence to implant techniques, heparin bridging, and pump speeds ≥9,000 RPMs resulted in a significantly lower risk of PT (1.9% vs 8.9%; p < 0.01) and lower composite risk of suspected thrombosis, hemolysis, and ischemic stroke (5.7% vs 17.7%; p < 0.01) at 6 months. CONCLUSIONS Adoption of all components of a structured surgical implant technique and clinical management strategy (PREVENT recommendations) is associated with low rates of confirmed PT.

In-hospital outcomes of a minimally invasive off-pump left thoracotomy approach using a centrifugal continuous-flow left ventricular assist device

BACKGROUND Minimally invasive left thoracotomy (MILT) and off-pump implantation strategies have been anecdotally reported for implantation of the HeartWare ventricular assist device (HVAD). We analyzed our experience with off-pump MILT implantation techniques and compared early in-hospital outcomes with conventional on-pump sternotomy (CS) implantation strategy. METHODS Between January 2013 and February 2014, 51 patients underwent HVAD implantation and were included in this study. Thirty-three patients had CS, whereas 18 patients underwent off-pump MILT. To compare outcomes of these techniques, a multivariate analysis using propensity score modeling was performed after adjusting for age, INTERMACS, Kormos and Leitz-Miller (LM) scores. RESULTS Mean age at implant was 57 (range 18 to 69) years, and overall in-hospital mortality was 8%. Univariate analysis revealed a statistically significant reduction in days on inotropes (p = 0.04), and a trend toward reduced intra-operative blood product administration (p = 0.08) in the MILT group. There was no difference in intensive-care-unit length of stay (p = 0.5), total length of stay (p = 0.76), post-operative blood product administration (p = 0.34) and total time on mechanical ventilation (p = 0.32). After adjusting for age, INTERMACS profile and Kormos and LM scores, no statistically significant differences were observed between the MILT and CS groups. CONCLUSIONS An off-pump MILT implantation strategy can be utilized as a safe surgical approach for patients undergoing HVAD implantation. Further large collaborative studies are needed to identify advantages of the MILT approach.

Left thoracotomy HeartWare implantation with outflow graft anastomosis to the descending aorta: a simplified bridge for patients with multiple previous sternotomies.

Advances in mechanical circulatory support have been critical in bridging patients awaiting heart transplantation. In addition, improvement in device durability has enabled left ventricular assist device therapy to be applied as destination therapy in those not felt to be transplant candidate. Because of the increasing complexity of patients, there continues to be a need for alternative strategies for device implantation to bridge high-risk patients awaiting heart transplantation, wherein the risks of numerous previous sternotomies may be prohibitive. We present a unique technique for placement of the HeartWare ventricular assist device via left anterior thoracotomy to the descending aorta in a patient awaiting heart transplantation with a history of multiple previous sternotomies.

Right ventricular afterload sensitivity dramatically increases after left ventricular assist device implantation: A multi-center hemodynamic analysis

BACKGROUND Right ventricular (RV) failure is a source of morbidity and mortality after left ventricular assist device (LVAD) implantation. In this study we sought to define hemodynamic changes in afterload and RV adaptation to afterload both early after implantation and with prolonged LVAD support. METHODS We reviewed right heart catheterization (RHC) data from participants who underwent continuous-flow LVAD implantation at our institutions (n = 244), excluding those on inotropic or vasopressor agents, pulmonary vasodilators or additional mechanical support at any RHC assessment. Hemodynamic data were assessed at 5 time intervals: (1) pre-LVAD (within 6 months); (2) early post-LVAD (0 to 6 months); (3) 7 to 12 months; (4) 13 to 18 months; and (5) very late post-LVAD (18 to 36 months). RESULTS Sixty participants met the inclusion criteria. All measures of right ventricular load (effective arterial elastance, pulmonary vascular compliance and pulmonary vascular resistance) improved between the pre- and early post-LVAD time periods. Despite decreasing load and pulmonary artery wedge pressure (PAWP), RAP remained unchanged and the RAP:PAWP ratio worsened early post-LVAD (0.44 [0.38, 0.63] vs 0.77 [0.59, 1.0], p < 0.001), suggesting a worsening of RV adaptation to load. With continued LVAD support, both RV load and RAP:PAWP decreased in a steep, linear and dependent manner. CONCLUSIONS Despite reducing RV load, LVAD implantation leads to worsened RV adaptation. With continued LVAD support, both RV afterload and RV adaptation improve, and their relationship remains constant over time post-LVAD. These findings suggest the RV afterload sensitivity increases after LVAD implantation, which has major clinical implications for patients struggling with RV failure.

Benefits of ambulatory axillary intra-aortic balloon pump for circulatory support as bridge to heart transplant.

OBJECTIVE Axillary intra-aortic balloon pump therapy has been described as a bridge to transplant. Advantages over femoral intra-aortic balloon pump therapy include reduced incidence of infection and enhanced patient mobility. We identified the patients who would benefit most from this therapy while awaiting heart transplantation. METHODS We conducted a single-center, retrospective observational study to evaluate outcomes from axillary intra-aortic balloon pump therapy. These included hemodynamic parameters, duration of support, and success in bridging to transplant. We selected patients on the basis of history of sternotomy, elevated panel-reactive antibody, and small body habitus. Patients were made to ambulate aggressively beginning on postoperative day 1. RESULTS Between September 2007 and September 2010, 18 patients underwent axillary intra-aortic balloon pump therapy. All patients had the devices placed through the left axillary artery with a Hemashield side graft (Boston Scientific, Natick, Mass). Before axillary placement, patients underwent femoral placement to demonstrate hemodynamic benefit. Duration of support ranged from 5 to 63 days (median = 19 days). There was marked improvement in ambulatory potential and hemodynamic parameters, with minimal blood transfusion requirements. There were no device-related infections. Some 72% of the patients (13/18) were successfully bridged to transplantation. CONCLUSIONS Axillary intra-aortic balloon pump therapy provides excellent support for selected patients as a bridge to transplant. The majority of the patients were successfully bridged to transplant and discharged. Although this therapy has been described in previous studies, this is the largest series to incorporate a regimen of aggressive ambulation with daily measurements of distances walked.

Right ventricular plasticity and functional imaging

Right ventricular (RV) function is a strong independent predictor of outcome in a number of distinct cardiopulmonary diseases. The RV has a remarkable ability to sustain damage and recover function which may be related to unique anatomic, physiologic, and genetic factors that differentiate it from the left ventricle. This capacity has been described in patients with RV myocardial infarction, pulmonary arterial hypertension, and chronic thromboembolic disease as well as post-lung transplant and post-left ventricular assist device implantation. Various echocardiographic and magnetic resonance imaging parameters of RV function contribute to the clinical assessment and predict outcomes in these patients; however, limitations remain with these techniques. Early diagnosis of RV function and better insight into the mechanisms of RV recovery could improve patient outcomes. Further refinement of established and emerging imaging techniques is necessary to aid subclinical diagnosis and inform treatment decisions.

Does Renal Dysfunction and Method of Bridging Support Influence Heart Transplant Graft Survival

BACKGROUND Renal insufficiency is common in status 1B patients supported with inotropes or a continuous flow left ventricular device (CF-LVAD) as a bridge to heart transplantation. We evaluated the association of renal function and inotrope versus CF-LVAD support on posttransplant graft survival in status 1B patients. METHODS The Scientific Registry for Transplant Recipients database was analyzed for posttransplant survival in status 1B patients bridged with inotropes or CF-LVAD who underwent transplantation between 2003 and 2012. Pretransplant renal function was measured by estimating glomerular filtration rate (GFR) and was stratified as less than 45 mL · min(-1) · 1.73 m(-2), 45 to 59, and 60 or greater. Univariate Kaplan-Meier and multivariate Cox regression models were used to evaluate the main effects of GFR strata and inotropes versus CF-LVAD, and the interaction effect of GFR strata by CF-LVAD, on graft survival. RESULTS This study included 4,158 status 1B patients (74% male, aged 53 ± 12 years). Of those, 659 patients had a CF-LVAD (HeartMate-II [Thoratec, Pleasanton, CA], n = 638; HVAD [HeartWare, Framingham, MA], n = 21), and 3,530 were receiving inotropes (31 CF-LVAD patients were also receiving inotropes). Kaplan-Meier analyses demonstrated reduced graft survival (p = 0.022) in patients with pretransplant GFR less than 45 versus GFR 45 to 59 (p = 0.062) and versus GFR 60 or greater (p = 0.007), and no effect of inotrope versus CF-LVAD support on graft survival (p = 0.402). Multivariate analysis demonstrated that, after adjusting for the main effects of GFR stratum, CF-LVAD, and inotropes, status 1B patients bridged with a CF-LVAD and GFR in the lowest stratum had reduced graft survival (interaction effect p = 0.040). CONCLUSIONS Pretransplant renal insufficiency was associated with reduced posttransplant graft survival in status 1B patients. This risk is increased for patients bridged with a CF-LVAD (versus inotropes) who have GFR in the lowest stratum.

Hemodynamic Transesophageal Echocardiography After Left Ventricular Assist Device Implantation

OBJECTIVE The authors hypothesized that the clinical profile of patients undergoing hTEE after continuous flow left ventricular assist device (CF-LVAD) implant would be in patients with greater acuity, more blood product utilization, and longer length of ICU stay, and that hTEE would change clinical management. DESIGN Retrospective review. SETTING University hospital. PARTICIPANTS One hundred consecutive patients receiving a CF-LVAD. INTERVENTIONS Retrospective review using a standardized electronic form of a miniaturized disposable transesophageal echocardiography probe that documented not only physical findings but also changes in hemodynamic management (hTEE) in CF-LVAD patients. MEASUREMENTS AND MAIN RESULTS Of the 100 patients, 41 received an hTEE probe. The INTERMACS score, Leitz-Miller Score, and Kormos score indicated the hTEE group had a statistically significant greater risk of morbidity and mortality. Interoperatively, the hTEE group received more blood products and was more likely to have an open chest. Postoperatively, the hTEE group received more blood products, had a longer total length of stay, and had increased mortality. ICU length of stay, days on inotropes and days on mechanical ventilation were not statistically significant between the 2 groups. Information obtained from hTEE changed ICU management in 72% of studies. CONCLUSION Retrospective review of CF-LVAD patients revealed that postoperative hTEE is used in sicker CF-LVAD patients and frequently leads to changes in ICU clinical management.

Development of acquired von Willebrand syndrome during short-term micro axial pump support: implications for bleeding in a patient bridged to a long-term continuous-flow left ventricular assist device.

Percutaneous continuous-flow (CF) micro axial blood pumps, like the Impella 5.0, are commonly used for short-term (ST) mechanical circulatory support in patients with acute decompensated heart failure. The Impella device often serves as a bridge to implantation of a long-term (LT) CF left ventricular assist device (CF-LVAD), such as the centrifugal-flow HeartWare (HVAD). All patients supported with axial CF-LVADs develop acquired von Willebrand syndrome (AVWS) as a result of mechanical shear stress. Increased shear stress leads to excessive proteolysis of von Willebrand factor and loss of high molecular weight multimers, thus contributing to platelet dysfunction and increased gastrointestinal bleeding. Bleeding events associated with AVWS have been reported in patients supported with LT CF-LVADs; however, the relation between early perioperative bleeding complications and AVWS remains poorly characterized in ST CF-LVADs. We sought to describe the relation between the development of AVWS and excessive intraoperative bleeding in a patient who was sequentially bridged with an ST micro axial device to a LT centrifugal CF-LVAD. This case highlights the importance of monitoring these hemostatic changes when bridging to LT CF-LVADs.

Mechanical Circulatory Support and Heart Transplantation: Donor and Recipient Factors Influencing Graft Survival

BACKGROUND Mechanical circulatory support is an accepted strategy to bridge patients to heart transplantation (HTx). Among mechanical circulatory support patients who go on to HTx, factors associated with improved graft survival have not been fully elucidated. METHODS Using the Scientific Registry for Transplant Recipients, we identified adults who were treated with a left ventricular assist device (LVAD) or total artificial heart (TAH) before HTx. Kaplan-Meier and multivariate Cox regression models were used to identify patient, donor, and device characteristics associated with graft survival. RESULTS Between January 1997 and February 2012, 2,785 adults underwent HTx. Before HTx, 2,674 patients were treated with a LVAD (HeartMate XVE, 724; HeartMate II, 1,882; HeartWare, 68), and 111 were treated with a TAH. Follow-up averaged 25 ± 24 months. Gender mismatch occurred in 23%. Graft survival did not differ between LVAD groups (all p > 0.168), but TAH was associated with reduced graft survival compared with LVADs (p < 0.001). After controlling for device type (LVAD vs TAH), lower recipient pulmonary vascular resistance, shorter ischemic time, younger donor age, donor-to-recipient gender match, and higher donor-to-recipient body mass index ratio were independent predictors of longer graft survival (all p < 0.05). CONCLUSIONS TAH was associated with reduced graft survival after transplant, and survival did not differ between the LVAD device groups. Additional variables that were independently associated with graft survival were donor age, recipient peripheral vascular resistance, ischemic time, gender match, and donor-to-recipient body mass index ratio. Recognition of these factors may inform decisions regarding device support and donor suitability.