M.E. Davis

Adverse events in contemporary continuous-flow left ventricular assist devices: A multi-institutional comparison shows significant differences

OBJECTIVES We review differences in the incidence and timing of adverse events in patients implanted with continuous-flow left ventricular assist devices (LVADs), using the Mechanical Circulatory Support Research Network registry. METHODS From May 2004 to September 2014, a total of 734 patients (591 men; median age: 59 years) underwent primary continuous-flow LVAD implantation at our institutions. Patients implanted with the HeartMate II (HMII) (560 [76%] patients), compared with the HeartWare ventricular assist device (HVAD; 174 [24%]) were more often receiving destination therapy (47% vs 20%; P < .01), had a lower preoperative creatinine level (1.2 vs 1.3; P = .01), and had less median preoperative right ventricular dysfunction (mild vs moderate; P < .01). Ischemic etiology, prior sternotomy, and median INTERMACS profile were similar. RESULTS Overall mortality was 54 of 734 (7.4%); 41 of 560 (7.3%) in the HMII group, and 13 of 174 (7.5%) in the HVAD group (P = .95). Follow-up was available in 100% of early survivors for a median of 1 year (max: 10 years) and a total of 1120 patient-years of support (HMII: 940 patient-years [median: 1.1 years, max: 5.3 years] and HVAD: 180 patient-years [median: 0.6 year, max: 10.4 years]). On multivariable analysis, GI bleeding (P = .63), any infection (P = .32), driveline infection (P = .10), and pump thrombus (P = .64) were similar between devices while HeartWare HVAD was associated with higher risk of stroke (HR: 1.8, [1.25, 2.5], P = .003). CONCLUSIONS In this pooled analysis, a trend was found for higher incidence of percutaneous driveline infections in patients treated with the HMII; a higher incidence of stroke and time-related cumulative risk of any infection and stroke was found in patients treated with the HVAD, which was independently associated with higher stroke risk.

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.

Uncorrected pre-operative mitral valve regurgitation is not associated with adverse outcomes after continuous-flow left ventricular assist device implantation

BACKGROUND Mitral valve regurgitation (MR) is prevalent in patients with heart failure. Because very few data exist examining the influence of significant pre-operative MR on outcomes after left ventricular assist device (LVAD) implantation, we evaluate our experience. METHODS Between October 1996 and August 2013, 756 patients underwent primary LVAD implantation at our institutions. Of these, 508 patients received a continuous-flow LVAD and represent the contemporary cohort for this analysis. Devices implanted included the HeartMate II in 410 patients (81%) and HeartWare HVAD in 98 patients (19%). Based on availability of pre-operative echocardiography, 491 patients were divided into 2 study groups according to degree of pre-operative MR; 189 patients (39%) had moderate to severe or greater MR (MR group), and 302 (61%) had less than moderate to severe MR (less MR group). Median age at operation (60 years in MR group vs 58 years in less MR group, p = 0.19), male sex (78% in MR group vs 81% in less MR group, p = 0.42), and ischemic etiology (46% in MR group vs 51% in less MR group, p = 0.35) were similar between groups. RESULTS There were 40 early deaths (7.9%), and follow-up was available in all 468 early survivors for 641 patient-years of support. Patients in the MR group had higher late survival (2 years, 75%; 4 years, 65%) compared with patients in the less MR group (2 years, 66%; 4 years, 48%; p < 0.04). Cox proportional hazards model confirmed the independent interaction between MR and late survival (hazard ratio 0.62, p = 0.04). CONCLUSIONS There was improved survival in patients with severe pre-operative MR after continuous-flow LVAD implantation in our cohort. These findings may lend insight into the possible lack of value of addressing significant MR at the time of LVAD implantation.

Minimally invasive and alternative approaches for long-term LVAD placement: the Vanderbilt strategy.

BACKGROUND Minimally invasive and alternative strategies for implantation have been anecdotally reported for contemporary continuous-flow left ventricular assist device (CF-LVAD) placement. METHODS We reviewed our experience at a single center with alternative strategies for implantation of the HeartMate II and HeartWare CF-LVADs, in patients with advanced heart failure (HF). This featured article focuses on the associated surgical techniques and patient management pitfalls. RESULTS For appropriately selected cases, our group believes that these alternative strategies allow for the development of novel and less traumatic surgical approaches for CF-LVAD implantation. With reproducible outcomes, these approaches also promise the possibility of increasing the number of high-risk surgical patients who could benefit from CF-LVAD therapies. CONCLUSIONS This work has detailed a variety of less invasive alternative strategies for implantation of long-term LVADs. These newer approaches have the potential for significant advancements in the field of cardiothoracic surgery. Large-scale collaborative studies will be needed to clarify the potential advantages and disadvantages of these novel techniques on patient outcomes.

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.

Immediate recovery of acquired von Willebrand syndrome after left ventricular assist device explantation: implications for heart transplantation.

All patients supported with continuous flow-left ventricular assist devices (CF-LVADs) develop acquired von Willebrand syndrome due to the loss of von Willebrand factor (vWF) high molecular weight (HMW) multimers and this phenomenon has been associated with clinical manifestation of bleeding diatheses. The precise timing of postoperative recovery of HMW multimers and correction of this condition after CF-LVAD explantation and heart transplantation is unknown. We sought to determine the specific timing of HMW multimer recovery by serially quantifying plasma vWF multimer ratios after CF-LVAD explant and orthotopic heart transplantation (OHT) in a patient implanted with a HeartWare ventricular assist device. Using densitometric analysis of multimer patterns, we demonstrated complete recovery of HMW multimers within the first few hours following CF-LVAD explant and OHT. These findings have critical implications in the context of perioperative bleeding diatheses in patients bridged to transplantation with a CF-LVAD.

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.

Readmissions After Continuous Flow Left Ventricular Assist Device Implantation: Differences Observed Between Two Contemporary Device Types.

Readmissions after continuous flow left ventricular assist devices implantation are common. We compared the frequency and etiology of readmissions between two continuous flow left ventricular assist devices 6 months after implant. We retrospectively assessed readmissions in 81 patients who received a bridge to transplant HeartMate-II (HM-II) n = 35, 43% or HeartWare (HW) n = 46, 57%, from 2009 to 2014. Readmissions were divided into cardiac, infection, gastrointestinal bleeding, stroke, pump thrombosis, and miscellaneous profiles. Age, gender, creatinine, INTERMACS profiles were comparable between groups (p > 0.05). Sixty-one patients accounted for 141 readmissions. At 6 months, the overall readmission rate was higher among HM-II versus HW recipients (2.3 ± 1.7 vs. 1.4 ± 1.3; p = 0.024). Multiple readmissions (≥2) occurred more frequently in HM-II recipients (HM-II 23, 66% vs. HW 20, 44%; p = 0.047) which accounted for 87% of overall readmission frequency. Cardiac profile was the most common reason for readmission (HM-II = 15, HW = 17; p = 0.95). Readmission for arrhythmia (HM-II = 10, HW = 3; p = 0.021) and overall infection rate (0.49 ± 0.70 vs. 0.17 ± 0.68; p = 0.001) were more common among HM-II recipients; however, other readmission profiles were comparable between devices (p > 0.05). Readmission frequency, multiple readmissions, and clinical profile characteristics were different between HM-II and HW recipients.

Perioperative Blood Product Use: A Comparison Between HeartWare and HeartMate II Devices

BACKGROUND The HeartWare (HW) (Framingham, MA) and the HeartMate II (HM II) (Thoratec Inc, Pleasanton, CA) continuous-flow left ventricular assist devices (CF-LVADs) are commonly used to bridge patients to transplantation. We hypothesized that there are differences in perioperative blood product (BP) use and chest tube (CT) output between CF-LVAD types. METHODS We retrospectively evaluated BP use in 71 patients who were implanted with a CF-LVAD (HM II = 38; HW = 33) by median sternotomy for bridge to transplantation (BTT) indications from 2009 to 2013. Detailed BP use data were collected during the intraoperative and postoperative periods and included packed red blood cells, platelets, fresh frozen plasma, and cryoprecipitate. RESULTS Preoperative characteristics (age, left ventricular ejection fraction, previous sternotomy, ischemic cause), and risk stratification scores (Interagency Registry for Mechanically Assisted Circulatory Support [INTERMACS]) profile, Leitz-Miller score, Kormos score) were comparable between groups (all p > 0.05). Total average intraoperative and postoperative BP use was different between device types: HW = 8.3 ± 13 versus HM II = 12.6 ± 14.0 units (p = 0.002) and HW = 6.1 ± 12.0 units compared with HM II = 13.5 ± 24.1 units (p = 0.022), respectively. Average postoperative CT output for HW (3,231 ± 3,648 mL) and HM II (3,463 ± 3,050) (p < 0.008) were different between device types. Multivariate analysis revealed that a higher preoperative Leitz-Miller score, implantation of an HM II CF-LVAD, previous sternotomy, and a longer duration of cardiopulmonary bypass (CPB) time were independently associated with increased need for BP use, whereas only use of the HM II device and a longer bypass time predicted a greater CT output. CONCLUSIONS Compared with HM II, implantation of the HW CF-LVAD was associated with reduced intraoperative and postoperative BP use and decreased CT output. Increased awareness of device-related differences in bleeding and BP use may improve CF-LVAD patient outcomes.