Nicholas A. Haglund

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.

Treatment of device thrombus in the HeartWare HVAD: Success and outcomes depend significantly on the initial treatment strategy

BACKGROUND Pump thrombosis is a major adverse event in patients supported with a left ventricular assist device (LVAD). Treatment approaches include device exchange, lytic therapy, or augmentation of anticoagulation or antiplatelet therapy. The optimal strategy in the HeartWare HVAD Ventricular Assist System (HeartWare, Framingham, MA) is uncertain, and because few large studies have examined differing treatment outcomes, we have reviewed findings from the Mechanical Circulatory Support Research Network registry. METHODS Between March 2009 and August 2014, 175 patients (133 male) underwent implantation of the HeartWare HVAD at institutions that comprise the Mechanical Circulatory Support Research Network. Median age at implant was 59 years (range, 18-76 years). Follow-up was available in all patients for a median of 6 months (maximum, 61 months) and for a total of 163 patient-years of support. There were 36 pump thromboses (using Interagency Registry for Mechanically Assisted Circulatory Support criteria) in 21 patients for a total event rate of 0.22 events/patient-year of support; 13 patients had 1 event, 4 had 2, 2 had 3, 1 had 4, and 1 had 5. The median time to the first thrombosis was 6.4 months, and to each subsequent thrombosis was 4, 3, 2, and 2 months, respectively. Primary treatment success was defined as the patient remaining alive and within the first 30 days of the initial treatment be free from stroke, recurrence of pump thrombosis, device exchange, or urgent transplantation (United Network of Organ Sharing Status 1A). Medical treatment was defined as tissue plasminogen activator, heparin plus glycoprotein IIb/IIIa inhibitor, or heparin alone, not followed by surgical treatment within 72 hours. RESULTS Initial medical treatment was used in 29 episodes (tissue plasminogen activator in 24, heparin alone in 4, and heparin plus glycoprotein IIb/IIIa in 1) and surgical (device exchange) in 7. Medical treatment was successful in 14 of 29 episodes (48%). Complications of medical treatment included hemorrhagic stroke in 6 patients (21%), need for urgent device exchange/transplant in 6 (21%), and death in 3 (10%). Surgical treatment was successful in all 7 patients (100%). No significant early complications or early deaths occurred after device exchange. CONCLUSIONS In this large multicenter analysis, we observed that medical therapy, as the initial treatment strategy for HeartWare HVAD thrombosis, is associated with low success (48%) and a significant risk of hemorrhagic stroke (21%) and death (10%). However, initial treatment with device exchange was uniformly successful and not associated with significant early morbidity or death. Although the optimal treatment approach for HeartWare HVAD pump thrombosis remains undecided, these data do not support the routine use of medical therapy as an initial treatment strategy.

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.

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.

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.

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.