Thoratec Corporation Research Articles

Intraventricular Flow Patterns in Patients Treated with Left Ventricular Assist Devices.

The success of left ventricular assist device (LVAD) therapy is hampered by complications such as thrombosis and bleeding. Understanding blood flow interactions between the heart and the LVAD might help optimize treatment and decrease complication rates. We hypothesized that LVADs modify shear stresses and blood transit in the left ventricle (LV) by changing flow patterns and that these changes can be characterized using 2D echo color Doppler velocimetry (echo-CDV). We used echo-CDV and custom postprocessing methods to map blood flow inside the LV in patients with ongoing LVAD support (Heartmate II, N = 7). We compared it to healthy controls (N = 20) and patients with dilated cardiomyopathy (DCM, N = 20). We also analyzed intraventricular flow changes during LVAD ramp tests (baseline ± 400 rpm). LVAD support reversed the increase in blood stasis associated with DCM, but it did not reduce intraventricular shear exposure. Within the narrow range studied, the ventricular flow was mostly insensitive to changes in pump speed. Patients with significant aortic insufficiency showed abnormalities in blood stasis and shear indices. Overall, this study suggests that noninvasive flow imaging could potentially be used in combination with standard clinical methods for adjusting LVAD settings to optimize flow transport and minimize stasis on an individual basis.

Left Ventricular Assist Device (LVAD) in Singapore: A Nation's 10 Year Experience

Continuous flow left ventricular assist devices (LVADs) have become part of the mainstay of management in Singapore's transplant scarce population, whether as a bridge-to-transplant or as definitive management for refractory heart failure. We report our nation's experience with the use of 2 LVADs, the HeartMate II, HeartMate HVAD, & the HeartMate III from May 2009-May 2019. From may 2009 to May 2019, 100 patients underwent implantation of 100 CF LVADs, HeartMate II (Thoratec Corp. Pleasanton, CA n= 60) or HeartMate III (Abott, n=17) or HVAD (HeartWare Inc., Framingham, MA; n = 23). Of this, 72 were implanted as bridge to transplant, 27 implanted as destination therapy and 1 implanted as bridge to recovery. A comparative analysis using exact binomial test was performed against global International Society for Heart and Lung Transplantation (ISHLT) Mechanically Assisted Circulatory Support (IMACS) registry. Mean age was 51.06 with 83 male and 17 female patients. 30 patients were INTERMACS I, 20 patients INTERMACS II, 37 patients INTERMACS III, 12 patients INTERMACS IV and 1 INTERMACS V. We had 0 INTERMACS VI and VII patients. The early complication rate of the cohort, HeartMate II, HeartMate III & HeartWare were as follows: 84.0%, 95%, 70.6% and 65.2% respectively. Perioperative mortality (within 30 days) in the same order was 8.0%, 8.33%, 11.8%, and 4.35%. Amongst the early complications, the most common was infections at 59.0%, followed by renal dysfunction 35.0% arrhythmias 30.0%, hemorrhagic events 27.0%, pericardial effusions 14.0% & lastly thromboembolic events 6.00% We report a higher 2-year survival (81% p = 0.0089) and 3-year survival (80% p=0.000023) compared to IMACS registry but also a higher early infection rate in 59%. Other complications were not statistically significant. The use of LVAD is promising as both BTT & definitive management in the Singapore population. Despite the relatively low volume performed in our nation, our complication rates are similar to international standards. This is likely due to the strict selection criteria with rigorous workup by a dedicated LVAD team. Our higher infection rates are possibly due to the warm and humid climate in Southeast Asia. In this promising era of changing improvements in MCS, we believe our nation can seek to improve future outcomes of our patients.

A left ventricular end-diastolic dimension less than 6.0 cm is associated with mortality after implantation of an axial-flow pump

ObjectiveThe effects of having a lower left ventricular end-diastolic dimension before HeartMate II (Thoratec Corp, Pleasanton, Calif) left ventricular assist device implantation remain unclear. We analyzed our single-center data on HeartMate II implantation to determine whether having a lower left ventricular end-diastolic dimension preoperatively was associated with inferior outcomes. MethodsFrom November 2003 to March 2016, 393 patients with chronic heart failure underwent primary HeartMate II implantation. We compared the preoperative left ventricular end-diastolic dimension and associated survival outcomes of these patients to determine the left ventricular end-diastolic dimension cutoff for worse overall survival. Then, we compared the preoperative demographics, stroke rate, and mortality of patients with a left ventricular end-diastolic dimension above the cutoff for worse survival with those of patients with a left ventricular end-diastolic dimension below the cutoff. ResultsA Cox multivariate regression model showed that low left ventricular end-diastolic dimension was an independent predictor of mortality (hazard ratio, 1.49; P = .02). The Contal and O'Quigley method showed that overall survival postimplantation was decreased in patients with a left ventricular end-diastolic dimension less than 6.0 cm (n = 91). Kaplan–Meier analysis confirmed that the left ventricular end-diastolic dimension less than 6.0 cm group had lower overall survival than the left ventricular end-diastolic dimension 6.0 cm or greater group (P = .04). Furthermore, a competing-risk analysis showed that postoperative stroke was more common in the left ventricular end-diastolic dimension less than 6.0 cm group than in the left ventricular end-diastolic dimension 6.0 cm or greater group (P < .01). ConclusionsOverall survival was decreased and postoperative stroke was increased in HeartMate II recipients with a preoperative left ventricular end-diastolic dimension less than 6.0 cm. Future research should determine the left ventricular end-diastolic dimension cutoff values for safely implanting other support devices, and device designs should be improved to better accommodate the needs of patients with a limited left ventricle size.

QRS Shortens after Left Ventricular Assist Device Implantation

QRS Shortens after Left Ventricular Assist Device Implantation

Ventricular Assist Devices: The Basics

As the cases of heart failure continue to rise, more ventricular assist devices are likely to be implanted. Providers in a variety of care environments are more likely to see patients with ventricular assist devices because they are living longer; therefore, it is necessary for providers to understand the unique care and complications related to these devices, such as thrombosis, stroke, bleeding, right-sided heart failure, ventricular dysrhythmias, and infection. The current literature regarding the complications and management of patients with these devices was reviewed and summarized, with a focus on HeartWare (HeartWare International Inc, Framingham, MA) and HeartMate II (Thoratec Corp, Pleasanton, CA).

Model of End-Stage Liver Disease-eXcluding International Normalized Ratio (MELD-XI) Scoring System to Predict Outcomes in Patients Who Undergo Left Ventricular Assist Device Implantation

The use of continuous-flow left ventricular assist devices (CF-LVADs) to treat advanced heart failure is increasing. Although risk scores, such as Model for End-Stage Liver Disease and the HeartMate II Risk Score, require the use of the international normalized ratio, many patients are on anticoagulation before CF-LVAD implantation. This study evaluated the ability of the Model of End-Stage Liver Disease-eXcluding International Normalized Ratio (MELD-XI) scoring system to predict clinical outcomes in patients with advanced heart failure who undergo CF-LVAD implantation. A single-center retrospective review was performed of 524 patients who were implanted with the HeartMate II LVAD (Thoratec Corporation, Pleasanton, CA) or the HeartWare HVAD (HeartWare International Inc, Framingham, MA) between 2004 and 2016. Patients were stratified into two cohorts: those with a MELD-XI score of less than 14 (n= 301) and 14 or higher (n= 223). Patients with the higher-risk MELD-XI score of 14 or higher demonstrated lower survival rates at 1, 3, 6, 12, and 24 months (p < 0.001 for all) and increased risk of early right heart failure and infections compared with patients with MELD-XI score of less than 14. MELD-XI was not significantly inferior at predicting 90-day mortality compared with the HeartMate II Risk Score (p=0.92). Patients with elevated MELD-XI scores at follow-up demonstrated higher rates of mortality. These findings suggest that a MELD-XI score of 14 or higher was associated with a higher postoperative mortality rate than that seen in patients with a lower MELD-XI score. The MELD-XI scoring system can be used to predict outcomes in patients with advanced heart failure who undergo CF-LVAD implantation.

HeartMate 3 in Lowest INTERMACS Profile Cohort: The Swiss Experience.

New generation devices for long-term mechanical circulatory support are centrifugal pumps having fully magnetically levitated rotors to reduce blood trauma. Recently, the novel HeartMate 3 was cleared for clinical application in Switzerland. In two Swiss University Hospitals part of the "Lausanne-Geneva Transplantation Network," 10 consecutive patients in end-stage heart failure received the HeartMate 3 (Thoratec Corporation, Pleasanton, CA). Device implantation criteria were persistent low output syndrome despite optimal medical treatment. The primary end-point of the study was survival or transplantation to 90 days on the device. Five patients (50%) were in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) class 1 and 2 (two were under venoarterial extracorporeal membrane oxygenation [VA-ECMO]), and five were in class 3 and 4. The indication was bridge-to-transplant in seven patients, and destination therapy in three. Two patients (20%) received concomitant aortic valve surgery. Four patients (40%) required temporary right ventricle support (tRVAD) for a mean of 8 ± 1.5 days. Bleeding requiring surgical revision occurred in five (50%) patients, two during the tRVAD support. At the 90 day end-point, survival was 90%, one (10%) died due to respiratory failure. Three (30%) experienced critical illness polyneuropathy. Two had body temperature over 38.5°C for more than 7 days after implant, without infections. Two (20%) had late driveline infection. The pump allowed rapid improvement of patients' clinical conditions even in severely compromised patients. Postoperative bleeding occurred in the setting of anticoagulation. No hemolysis or pump thrombosis occurred. Fever occurred frequently but was not associated with mortality. Hemodynamic support was consistent over time without significant adverse events.

Abciximab/Heparin Therapy for Left Ventricular Assist Device Implantation in Patients With Heparin-Induced Thrombocytopenia

Optimal anticoagulation strategy remains uncertain in patients with heparin-induced thrombocytopenia (HIT) and undergoing left ventricular assist device (LVAD) implantation. We describe our protocol of abciximab and heparin in these patients. Our protocol is to administer abciximab, 0.25 mg/kg loading dose, followed by continuous infusion of 0.125 μg · kg-1 · min-1 throughout cardiopulmonary bypass. Full-dose heparin is then given with subsequent additional doses to maintain an activated clotting time of 400 seconds or longer. The abciximab infusion is stopped 15 minutes after heparin reversal with protamine, and platelets are transfused. Six patients underwent LVAD implantation with this protocol in our program. HIT was confirmed in 4 patients was suspected in 2, which was negative after the operation. One patient received a HeartMate XVE (Thoratec Corp, Pleasanton, CA) and the others received HeartMate II (Thoratec Corp). There were no thromboembolic complications. One patient required chest reexploration for bleeding and temporary right VAD support. Postoperative anticoagulation with argatroban was restarted on median postoperative day 3 (range, days 1 to 6) and warfarin was started on day 5 (range, days 3 to 12). Median postoperative intensive care unit stay was 9 days (range, 5 to 76 days), and hospital stay was 22 days (range, 18 to 132 days). After the initial LVAD implantation, 1 patient required HeartMate XVE LVAD exchange to HeartMate II and subsequent heart transplant, both of which were performed with the abciximab/heparin protocol. A HeartMate II device was explanted in another patient after myocardial recovery. The remaining 4 patients are alive on device support. This is the first report of a novel abciximab/heparin protocol for LVAD implantation in patients with HIT. The preliminary results suggest the feasibility and safety of this protocol.

Optimal Timing of Heart Transplant After HeartMate II Left Ventricular Assist Device Implantation

Optimal timing of heart transplantation in patients supported with second-generation left ventricular assist devices (LVADs) is unknown. Despite this, patients with LVADs continue to receive priority on the heart transplant waiting list. Our objective was to determine the optimal timing of transplantation for patients bridged with continuous-flow LVADs. A total of 301 HeartMate II LVADs (Thoratec Corp, Pleasanton, CA) were implanted in 285 patients from October 2004 to June 2013, and 86 patients underwent transplantation through the end of follow-up. Optimal transplantation timing was the product of surviving on LVAD support and surviving transplant. Three-year survival after both HeartMate II implantation and heart transplantation was unchanged when transplantation occurred within 9 months of implantation. Survival decreased as the duration of support exceeded this. Preoperative risk factors for death on HeartMate II support were prior valve operation, prior coronary artery bypass grafting, low albumin, low glomerular filtration rate, higher mean arterial pressure, hypertension, and earlier date of implant. Survival for patients without these risk factors was lowest when transplant was performed within 3 months but was relatively constant with increased duration of support. Longer duration of support was associated with poorer survival for patients with many of these risk factors. Device reimplantation, intracranial hemorrhage, and postimplant dialysis during HeartMate II support were associated with decreased survival. Survival of patients supported by the HeartMate II is affected by preoperative comorbidities and postoperative complications. Transplantation before complications is imperative in optimizing survival.

Left Ventricular Assist Device Thrombosis Is Associated With an Increase in the Systolic-to-Diastolic Velocity Ratio Measured at the Inflow and Outflow Cannulae

To determine whether the ratio of peak systolic-to-nadir diastolic velocity (S/D ratio) measured using Doppler at the left ventricular assist device (LVAD) inflow and outflow cannulae is associated with pump thrombosis and to determine whether there is an absolute decrease in the diastolic cannula velocities in LVAD thrombosis. Retrospective chart review. University hospital. Patients who underwent LVAD exchange. None. Transesophageal echocardiograms were reviewed from all patients with the HeartMate II device (Thoratec Corporation, Pleasanton, CA) over a 6-year period and who underwent LVAD exchange for pump thrombosis. The following 3 time points were evaluated: (1) initial LVAD placement (prethrombosis), (2) thrombosis, and (3) exchanged LVAD placement (postthrombosis). Systolic and diastolic flow velocities were examined using pulse-wave spectral Doppler at the inflow and outflow cannulae, and the S/D ratio for each was determined. Statistical analysis was performed with SAS, version 9.4 (SAS Institute, Cary, NC), using 2-tailed tests and alpha = 0.05. Thirteen patients were included in the study. Significant differences were observed in S/D ratios among the 3 phases at both the inflow (p = 0.0234) and outflow (p = 0.0047) cannulae. Pairwise tests of the inflow cannulae showed that the mean S/D ratio at the time of thrombosis (mean ± standard deviation [SD], 4.29 ± 1.74) was significantly greater than the prethrombosis ratio (2.49 ± 0.65; p = 0.0069). Among outflow measurements, the mean S/D ratio at thrombosis (3.94 ± 1.34) was significantly higher than both the prethrombosis (2.63 ± 0.56; p = 0.0025) and postthrombosis (2.74 ± 0.83) (p = 0.0093) ratios. Decreases in diastolic velocities were not statistically significant at the inflow cannula. At the outflow cannula, there was a significant difference in diastolic velocity among the phases (p = 0.0233). Specifically, the postthrombosis diastolic measurements (41.50 ± 9.94) were significantly higher than both the prethrombosis (26.85 ± 10.13; p = 0.0140) and thrombosis (26.7 ± 15.35; p = 0.0151) values. An increased S/D ratio measured with Doppler at the LVAD inflow and outflow cannulas may be associated with pump thrombosis. Decreased diastolic cannula velocities were not observed in LVAD thrombosis.

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

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. 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. 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. Adoption of all components of a structured surgical implant technique and clinical management strategy (PREVENT recommendations) is associated with low rates of confirmed PT.

Mechanical Circulatory Support as Bridge to Transplantation for the Failing Single Ventricle

Circulatory failure necessitating cardiac transplantation will ultimately develop in many patients with functional single-ventricle physiology. Interest in the use of mechanical circulatory support (MCS) in this population is growing. This was a retrospective case series of patients with functional single-ventricle physiology who underwent MCS with a ventricular assist device or a totalartificial heart as a bridge to cardiac transplantation between January 2006 and December 2014. Baseline demographics, intraoperative data, postoperative complications, and outcome data were collected from the medical record. MCS was used in 5 patients: HeartWare ventricular assist device (HeartWare International, Framingham, MA) in 1 patient, SynCardia total artificial heart (SynCardia Systems, Tucson, AZ) in 1, Thoratec Paracorporeal ventricular assist device (Thoratec Corp, Pleasanton, CA) in 1, and the Berlin Heart EXCOR (Berlin Heart Inc, The Woodlands, TX) in 2. The mean age at MCS was 12 ± 8 years. There were 2 early deaths at 12 and 28 days after MCS: 1 patient died of multiorgan system failure and 1 of neurologic injury. Overall, neurologic complications occurred in 3 patients (60%), and 1 patient (20%) required renal replacement therapy. Three patients (60%) underwent successful cardiac transplantation. The median time on the waiting list was 59 days (interquartile range, 18 to 126 days), and the median duration of MCS was 60 days (interquartile range, 28 to 93 days). At the time of transplant, all 3 patients were ambulatory, without the need for mechanical ventilation, and end-organ dysfunction had resolved. The 3 patients who received transplants were discharged from the hospital and were alive at an average follow-up of 9 ± 14 months. MCS can be successfully used as a bridge to transplantation in patients with a failing single-ventricle circulation. Use of MCS can allow for resolution of end-organ dysfunction and rehabilitation, leading to improved outcomes in this difficult population.

Ramp Study Hemodynamics, Functional Capacity, and Outcome in Heart Failure Patients with Continuous-Flow Left Ventricular Assist Devices.

Ramp studies-measuring changes in cardiac parameters as a function of serial pump speed changes (revolutions per minute [rpm])-are increasingly used to evaluate function and malfunction of continuous-flow left ventricular assist devices (CF-LVADs). We hypothesized that ramp studies can predict functional capacity, quality of life (QOL), and survival in CF-LVAD patients. Hemodynamic changes per Δrpm were measured at a minimum of CF-LVAD support, at baseline pump speed, and at maximal tolerable pump speed. Subsequently functional capacity and QOL were assessed. Eighty ramp tests were performed in 44 patients (HeartMate II, Thoratec Corporation, Pleasanton, CA). Functional status was evaluated in 70% (31/44); average 6 minute walk test (6MWT) was 312 ± 220 min, New York Heart Association (NYHA) I-II/III-IV (70/30%) and activity scores very low-low/moderate-very high (55/45%). Decrease in pulmonary capillary wedge pressure per Δrpm was related to better NYHA classification; NYHA I-II vs. III-IV, -0.29 ± 0.15 vs. -0.09 ± 0.16 mm Hg/rpm * 10 (p = 0.007) as well as to activity score; very low-low vs. moderate-very high, -0.16 ± 0.16 vs. -0.31 ± 0.16 mm Hg/rpm * 10 (p = 0.02). Cardiac output change per Δrpm was correlated to measures of QOL. Ramp tests did not predict survival. In conclusion, hemodynamic changes during ramp studies are associated with measures of functional capacity and QOL. Hence, such tests could potentially identify patients in risk of failure to thrive during CF-LVAD support.

Myocardial Structural and Functional Response After Long-Term Mechanical Unloading With Continuous Flow Left Ventricular Assist Device: Axial Versus Centrifugal Flow

ObjectivesThe aim of this study was to assess the impact of continuous-flow left ventricular assist device (LVAD) type—axial flow (AX) versus centrifugal flow (CR)—on myocardial structural and functional response following mechanical unloading. BackgroundThe use of continuous-flow LVADs is increasing steadily as a therapeutic option for patients with end-stage heart failure who are not responsive to medical therapy. Whether the type of mechanical unloading influences the myocardial response is yet to be determined. MethodsA total of 133 consecutive patients with end-stage heart failure implanted with continuous-flow LVADs (AX, n = 107 [HeartMate II Thoratec Corporation, Pleasanton, California]; CR, n = 26 [HeartWare, HeartWare International, Framingham, Massachusetts]) were prospectively studied. Echocardiograms were obtained pre-LVAD implantation and then serially at 1, 2, 3, 4, 6, 9, and 12 months post-implantation. ResultsThe 2 pump types led to similar degrees of mechanical unloading as assessed by invasive hemodynamic status and frequency of aortic valve opening. Myocardial structural and functional parameters showed significant improvement post-LVAD in both AX and CR groups. Left ventricular ejection fraction increased significantly from a mean of 18% to 28% and 26% post-LVAD in the AX and CR groups, respectively. Left ventricular end-systolic volume index and left ventricular end-diastolic volume index decreased significantly as early as 30 days post-implantation in the 2 groups. The degree of myocardial structural or functional response between patients in the AX or CR groups appeared to be comparable. ConclusionsLong-term mechanical unloading induced by AX and CR LVADs, while operating within their routine clinical range, seems to exert comparable effects on myocardial structural and functional parameters.

Outcomes after stroke complicating left ventricular assist device

Stroke is one of the leading complications during continuous flow-left ventricular assist device (CF-LVAD) support. Risk factors have been well described, although less is known regarding treatment and outcomes. We present a large single-center experience on stroke outcome and transplant eligibility by stroke sub-type and severity in CF-LVAD patients. Between January 1, 2008, and April 1, 2015, 301 patients underwent CF-LVAD (266 HeartMate II [HM I], Thoratec Corp, Pleasanton, CA; 35 HeartWare [HVAD], HeartWare International Inc, Framingham, MA). Stroke was defined as a focal neurologic deficit with abnormal neuroimaging. Intracerebral hemorrhage (ICH) definition excluded sub-dural hematoma and hemorrhagic conversion of an ischemic stroke (IS). Treatment in IS included intra-arterial embolectomy when appropriate; treatment in ICH included reversal of coagulopathy. Stroke severity was measured using the National Institutes of Health Stroke Scale (NIHSS). Outcomes were in-hospital mortality and transplant status. Stroke occurred in 40 patients: 8 ICH (4 HM II, 4 HVAD) and 32 IS (26 HM II, 6 HVAD). Among 8 ICH patients, there were 4 deaths (50%), with NIHSS of 18.8 ± 13.7 vs 1.8 ± 1.7 in survivors (p = 0.049). Among 32 IS patients, 12 had hemorrhagic conversion and 5 were treated with intra-arterial embolectomy. There were 9 deaths (28%), with NIHSS of 16.2 ± 10.8 vs 7.0 ± 7.6 in survivors (p = 0.011). Among the 32 IS patients, 12 underwent transplant, and 1 is awaiting transplant. No ICH patients received a transplant. In-hospital mortality after stroke is significantly affected by the initial neurologic impairment. Patients with IS appear to benefit the most from in-hospital treatment and often make sufficient recovery to be able to progress to transplant.

Traumatic pseudoaneurysm resulting from ruptured outflow graft due to disconnection of HeartMate II LVAD Bend Relief

We report a rare case of a 59-year-old male who presented with a pulsating pseudoaneurysm 15 months after placement of a HeartMate II left ventricular assist device (Thoratec Corporation, Pleasanton, CA, USA). Computed tomography and echocardiogram imaging and surgical exploration revealed that bend relief spontaneously detached from the outflow conduit, and the sharp edges of the snap ring component of the bend relief caused perforation to the outflow graft.<Learning objective: Left ventricular assist devices (LVADs) are of growing popularity within the field of cardiology as a means of bridge to transplant and as a destination therapy. This case highlights a rare, but potentially fatal complication of a popular LVAD, the HeartMate II. Since this case report, the US Food and Drug Administration has released a statement of this particular complication, and Thoratec has made changes to the design. However, many patients still have the older model in place, and are at risk of this rare but potentially fatal complication.>

Outpatient Outcomes of Pediatric Patients with Left Ventricular Assist Devices.

Outpatient experience of children supported with continuous-flow ventricular assist devices (CF-VAD) is limited. We reviewed our experience with children discharged with CF-VAD support. All pediatric patients <18 years old with CF-VADs implanted at our institution were included. Discharge criteria included a stable medication regimen, completion of a VAD education program and standardized rehabilitation plan, and presence of a caregiver. Hospital readmissions (excluding scheduled admissions) were reviewed. Adverse events were defined by Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) criteria. Of 17 patients with CF-VADs, 8 (47%) were discharged from the hospital (1 HeartWare ventricular assist device (Heartware Inc., Framingham, MA), 7 HeartMate II (Thoratec Corp, Pleasanton, CA)). Median age was 15.3 (range 9.6-17.1) years and weight was 50.6 (33.6-141) kg. Device strategies were destination therapy (DT; n = 4) and bridge to transplant (n = 4). Patients spent a median 49 (26-107) days hospitalized postimplant and had 2 (1-5) hospital readmissions. Total support duration was 3,154 patient-days, with 2,413 as outpatient. Most frequent adverse events were device malfunction and arrhythmias. There was one death because of pump thrombosis and no bleeding or stroke events. Overall adverse event rate was 15.22 per 100 patient-months. Early experience suggests that children with CF-VADs can be safely discharged. Device malfunction and arrhythmia were the most common adverse events but were recognized quickly with structured outpatient surveillance.

Asymptomatic Sustained Polymorphic Ventricular Tachycardia in a Patient with a Left Ventricular Assist Device: Case Report and what the Emergency Physician Should Know

BackgroundLeft ventricular assist devices (LVADs) are a viable treatment option for patients with end-stage heart failure. LVADs can improve survival, quality of life, and functional status. The indications for LVAD placement to support left ventricular function are temporary support, a bridge to transplantation, or destination therapy. Case ReportA 61-year-old man with past medical history significant for advanced congestive heart failure from ischemic cardiomyopathy, status post LVAD (HeartMate II; Thoratec Corporation, Pleasanton, CA) placement 2009 as destination therapy, presented to the Emergency Department (ED) with implantable cardiac defibrillators firing four times that morning. While in the care of Emergency Medical Services, he was in ventricular tachycardia, and they gave him a bolus of amiodarone 150 mg intravenously prior to arrival in the ED. He was reportedly alert and oriented without any chest pain on arrival to the ED, where an electrocardiogram was obtained showing polymorphic ventricular tachycardia. Why Should an Emergency Physician Be Aware of This?Emergency physicians must be familiar with the atypical presentations of potentially lethal dysrhythmias in this patient population. They must also be familiar with the major adverse events after LVAD implantation. These include device malfunction, cardiac dysrhythmias, bleeding, thromboembolism, neurological events, and infection. The causes of device malfunction can include thrombus formation with hemolysis, mechanical failure of the impeller, and driveline lead fractures with electric failure. Although time is critical in the heart failure patient with an LVAD failure or complication, expert consultation with cardiology or the LVAD specialist should occur when possible.

Clinical trial design and rationale of the Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy With HeartMate 3 (MOMENTUM 3) investigational device exemption clinical study protocol

The HeartMate 3 left ventricular assist system (LVAS; St. Jude Medical, Inc., formerly Thoratec Corporation, Pleasanton, CA) was recently introduced into clinical trials for durable circulatory support in patients with medically refractory advanced-stage heart failure. This centrifugal, fully magnetically levitated, continuous-flow pump is engineered with the intent to enhance hemocompatibility and reduce shear stress on blood elements, while also possessing intrinsic pulsatility. Although bridge-to-transplant (BTT) and destination therapy (DT) are established dichotomous indications for durable left ventricular assist device (LVAD) support, clinical practice has challenged the appropriateness of these designations. The introduction of novel LVAD technology allows for the development of clinical trial designs to keep pace with current practices. The prospective, randomized Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy With HeartMate 3 (MOMENTUM 3) clinical trial aims to evaluate the safety and effectiveness of the HeartMate 3 LVAS by demonstrating non-inferiority to the HeartMate II LVAS (also St. Jude Medical, Inc.). The innovative trial design includes patients enrolled under a single inclusion and exclusion criteria , regardless of the intended use of the device, with outcomes ascertained in the short term (ST, at 6 months) and long term (LT, at 2 years). This adaptive trial design includes a pre-specified safety phase (n = 30) analysis. The ST cohort includes the first 294 patients and the LT cohort includes the first 366 patients for evaluation of the composite primary end-point of survival to transplant, recovery or LVAD support free of debilitating stroke (modified Rankin score >3), or re-operation to replace the pump. As part of the adaptive design, an analysis by an independent statistician will determine whether sample size adjustment is required at pre-specified times during the study. A further 662 patients will be enrolled to reach a total of 1,028 patients for evaluation of the secondary end-point of pump replacement at 2 years.

A Decade of Experience With Continuous-Flow Left Ventricular Assist Devices

The use of continuous-flow left ventricular assist devices (CF-LVADs) has revolutionized the landscape of mechanical circulatory support for patients with heart failure. Clinical trials are already testing the next generation of CF-LVADs. In this study, our objective was to review our long-term experience with the current generation of CF-LVADs, specifically, the HeartMate (HM) II (Thoratec Corp, Pleasanton, CA). In this single-center retrospective analysis, we evaluated the records of 278 consecutive patients who underwent a total of 302 HM II placements from June 2005 through June 2014. We excluded 11 patients from our final study group, who had previously undergone placement of a HM XVE that failed. We divided the remaining 267 patients into 3 equal groups of 89 patients each, by time period: group 1, June 2005 through May 2009; group 2, June 2009 through January 2012; and group 3, February 2012 through June 2014. To examine differences in survival between our 3 groups, we used time-to-event analysis, including the Kaplan-Meier method. To examine secondary outcomes (including stroke, hemolysis, gastrointestinal bleeding, pump thrombus, and transplant), we used one-way analysis of variance. For our final study group of 267 patients, the total follow-up time was 479.01 patient-years (median, 469 days). The mean age of patients was 57 years; 81.4% were male. In all, 209 (78.9%) patients underwent HM II placement as a bridge to transplant; 58 (21.1%), as destination therapy (DT). The overall survival rate was 94% at 30 days, 77% at 1 year, 65% at 2 years, 60% at 3 years, 50% at 4 years, and 48% at 5 years. In bridge to transplant patients, the survival rate was 78% at 1 year and 66% at 2 years; in DT patients, 70% and 60%. In group 1 patients, the survival rate was 94% at 30 days, 64% at 1 year, and 48% at 2 years; in group 2, 93%, 88%, and 76%; and in group 3, 94%, 77%, and 73% (P = 0.003). In the later years of our study period, from June 2009 onwards (ie, in groups 2 and 3), we noted a statistically significant increase in HM II placement as DT, a reduction of driveline infections, increasing pump exchange, increasing hemolysis, a reduced frequency of transplants, and an improved survival rate (as compared with the earlier group 1). The HM II has favorably influenced the outcomes of patients with end-stage heart failure, yet major complications still limit their survival. Improving compatibility between the pump and the individual host patient, enhancing anticoagulation strategies, and developing a totally implantable pump might further reduce complications thereby improving survival times and allowing CF-LVAD placement to be a true long-term alternative to a heart transplant.