Pump Thrombosis Research Articles

Pump position and thrombosis in ventricular assist devices: Correlation of radiographs and CT data.

Malpositioning of left ventricular assist devices (LVAD) is a risk factor for thrombosis, but its identification from clinical imaging remains challenging. X-rays and CT scans were analyzed and parameters identified that correlated to pump thrombosis. Retrospective imaging data of patients (n = 115) with HeartmateII (HMII) or HVAD were analyzed in two groups (pump-thrombosis PT, n = 15 vs matched control group NT, n = 15) using routine X-rays and CT scans. In CT, directional deviations of the inflow cannula in three-chamber and two-chamber view (α and β angles) were identified. In HVAD PT frontal radiographs showed reduced pump body area and smaller minor axis (PT 41.3 ± 4.8 mm vs NT 34.9 ± 6.0 mm, p = 0.026), and in the lateral radiographs the visibility of the inflow cannula served as a predictive parameter for PT. In HMII patients, no parameters were associated with PT. The angle α differed significantly (NT −1.2 ± 7.5°, PT −22.0 ± 4.7°, p = 0.006) in HVAD patients. Further, correlations of x-ray parameters with CT angles α and β showed that radiographs can be used to identify malpositioned pumps. Well-aligned inflow cannula positions are essential. HVAD patients with a posterior rotation of the inflow cannula have a higher risk of pump thrombosis. This risk can reliably be identified from routine radiographs.

Three-year follow-up after less-invasive left ventricular assist device exchange to HeartMate 3™.

Device exchange to a newer generation left ventricular assist device (LVAD) offers the opportunity to benefit from improved adverse events profiles. We present the three-year results of a patient cohort undergoing VAD upgrades to a new generation device focusing on outcomes and adverse events. We present the first series of patients who underwent LVAD upgrade to HeartMate 3™ (Abbott Laboratories; Abbott Park, IL, USA). All operations were performed less invasively. Follow-up time was three years after LVAD exchange. Overall four HeartMate II™ (Abbott Laboratories; Abbott Park, IL, USA) and two HVAD patients underwent LVAD upgrade. In five cases severe infection of the VAD led to device exchange (83%, 5/6). Three-year survival after LVAD exchange was 100% (6/6). In the follow-up examinations one patient showed a single syncope and several low flow alarms (1/6). The remaining five patients showed no technical malfunctions of the LVAD or hemodynamic adverse events (5/6). Four out of five patients whose devices had to be changed due to an infection suffered a local re-infection (4/5), which did not require any further surgical intervention. Four patients were successfully transplanted, and two patients were still on device support at three years after LVAD exchange. Three-year outcomes and adverse events after LVAD exchange to HeartMate 3™ (Abbott Laboratories). show excellent results. The superior hemocompatibility in terms of pump thrombosis makes the HM3 a favored choice in case of LVAD exchange due previous pump thrombosis. However, in cases of exchange due to device infection the risk of re-infection remains high.

Axillary or Subclavian Impella 5.0 Support in Cardiogenic Shock: A Systematic Review and Meta-analysis

Summary data around survival and adverse events of cardiogenic shock (CS) patients supported with axillary or subclavian artery 5.0 Impella are presently unavailable. We performed a systematic search of studies reporting the outcomes of axillary or subclavian access 5.0 Impella for refractory CS in PubMed, EMBASE, and the Cochrane Library. The primary outcome was 30-day survival. Secondary outcomes included survival to next therapy and adverse events on support. Proportional meta-analysis was used to pool across studies. Of the 795 potential studies identified, 13 studies were included in the meta-analysis (n = 256 patients). The average age of patients across studies was 56 ± 5 years. Thirty-day survival for the overall cohort was 66% (95% CI: 59–73). Survival to the next therapy was 68% (95% CI: 60–76). The occurrence of adverse events over an average of 13 (95% CI: 12–14) days of support was the following: stroke 5.9%, hemolysis 27%, pump thrombosis 4.4%, limb ischemia 0.1%, major bleeding 5.4%, device malfunction 10.6%, exchange 6.6%, and infection 14%. In this systematic review and meta-analysis, we report survival and adverse event rates of axillary or subclavian access 5.0 Impella for CS. Such summary data can inform clinician decision-making.

Left ventricular assist device implantation in patients with left ventricular thrombus

An intra-cavitary left ventricular (LV) thrombus is a relative contraindication to LV assist device (LVAD) implantation based on increased thromboembolic risks. Herein, we present our experience with LVAD patients with or without preoperative diagnosis of LV-thrombus. We retrospectively investigated 563 patients who received LVAD implantation between 2004 and 2018. Diagnosis of LV-thrombus was verified with computed tomography scan, magnetic resonance imaging, echocardiography, or intraoperative LV inspection. The primary endpoint was 30-day survival free of stroke and pump thrombosis. Overall, 72 patients (12.8%) had a diagnosis of LV-thrombus. They were younger (51years; IQR:41-59), affected by severely reduced ejection fraction (15%; IQR:10-20), more often presenting with dilated cardiomyopathy (61.8%) and INTERMACS profile 1 (33.3%). Preoperative atrial fibrillation was frequent in patients without LV-thrombus (38.9%). Conventional sternotomy was the preferred approach in LV-thrombus patients (77.8%), based on more HMII implantations in these patients (41.7%). Survival free of strokes and pump thrombosis at 30days was comparable (P=.5751) between patients with (83.3%) or without LV-thrombus (80.9%). LVAD implantation in patients with preoperative LV-thrombus is safe and feasible. When managed through correct diagnostic and intraoperative strategies including accurate inspection of the LV cavity, these patients show similar 30-day outcomes compared to patients without LV-thrombus.

Impact of the whole activated clotting time during Impella support on short-term prognosis.

Impella (Abiomed, Danvers, MA, USA) is a percutaneous trans-catheter left ventricular assist device. Anticoagulant therapy targeting whole activated clotting time (ACT) between 160 and 180s is recommended to prevent pump thrombosis during support. However, we sometimes experience fatal bleeding despite achieving the target ACT range. Consecutive patients who received Impella support in our institute between March 2018 and October 2020 were included in this retrospective study. The association between the averaged ACT levels during the Impella support and 30-day mortality was investigated. A total of 36 patients (71years old, 61% males) were included. Most of the patients were managed within the recommended therapeutic range of ACT, and the average ACT level was 162s. The higher ACT group (> 168s) had older age, smaller body mass index, and higher serum creatinine compared with the lower ACT group (p < 0.05 for all). A higher ACT level was an independent risk factor of 30-day mortality with an adjusted hazard ratio of 1.085 (95% confidence interval 1.037-1.154) with a cut-off level of 168s. There were only two thromboembolic events. Patients managed with higher ACT levels had a higher risk of 30-day mortality during Impella support. A low-dose heparin purge solution might be recommended in patients with high-risk for bleeding events.

Contemporary outcomes of continuous-flow biventricular assist devices.

Significant right ventricular failure (RVF) complicating left ventricular assist device (LVAD) placement has been reported at 10-30%. Although primarily indicated for left ventricular failure, ventricular assist devices (VADs) have become utilized in a biventricular setup to combat right ventricular failure (RVF) following LVAD implantation. With the advent of continuous-flow LVADs (CF-LVADs) superseding their pulsatile predecessors, the shift towards CF-biventricular assist devices (CF-BiVADs) come with the prospect of improved outcomes over previous pulsatile BiVADs. We aim to review the literature and determine the outcomes of CF-BiVAD recipients. A systematic review was performed to determine the outcomes of CF-BiVADs. Pre-operative demographics and device configuration data was collected. Primary outcomes evaluated were short-term survival, long-term survival, duration of support, and survival to transplant. Secondary outcomes evaluated included intensive care unit (ICU) and hospital length of stay (ICU-LOS and HLOS, respectively), pump thrombosis, pump exchange. Median and interquartile range was reported where appropriate. A major limitation was the likely overlap of cohorts across publications, which may have contributed to some selection bias. Of 1,282 screened, 12 publications were evaluated. Sample size ranged from 4 to 93 CF-BiVAD recipients, and follow-up ranged from 6 to 24 months. Mean age ranged from 34 to 52 years old. Forty-five percent of CF-BiVADs had right atrial (RA-) inflow cannulation, with the remaining being right ventricular (RV). Thirty-day survival was a median of 90% (IQR 82-97.8%) and 12-month survival was a median of 58.5% (IQR 47.5-62%). Where reported, rate of pump thrombosis (predominantly the right VAD) was a median of 31% (IQR 14-36%), although pump exchange was only 9% (IQR 1.5-12.5%). RVF post-LVAD implantation is a high morbidity and mortality complication. There is no on-label continuous-flow RVAD currently available. Thus, the modifications of LVADs for right ventricular support to combat pump thrombosis has resulted in various techniques. BiVAD recipients are predominantly transplant candidates, and complications of pump thrombosis and driveline infection whilst on wait-list are of great consequence. This study demonstrates the need for an on-label CF-BiVAD.

First in man evaluation of a novel circulatory support device: Early experience with the Impella 5.5 after CE mark approval in Germany

The Abiomed Impella 5.5 (Danvers, MA) is a newly developed axial flow transaortic cardiac support device mounted on a 9 Fr steering catheter with a 21 Fr pump cannula. Impella 5.5 is intended for longer use and was approved for 30 days in 2018. This study evaluated the first-in-man series at six high-volume mechanical circulatory support centers in Germany after CE approval. The first 46 consecutive patients worldwide underwent implantation in six German centers between March 2018 and September 2019 for post-CE approval evaluation. The primary end-point was 30 days and 90 days all-cause mortality. The mean age of patients was 59.0 ± 11.5 years, and 43 (93.4%) were men. Half of the patients had acute on chronic heart failure. The main indication for Impella 5.5 implantation was ischemic cardiomyopathy and acute myocardial infarction (47.8%). The mean support time was 15.5 ± 24.2 days (range 0-164, median 10 days (IQR=7-19)) with a total of 712 patient-days on support. The 30 days and 90 days survival rates were 73.9% (95% CI: 63.3-88.9%) and 71.7% (95% CI: 60.7-87.1%), respectively. Additionally, 16 patients (34.8%) were weaned from the device for native heart recovery, and 19 (41.3%) were bridged to a durable device. Fifteen patients (32.6%) were mobilized to a chair, and 15 (32.6%) were ambulatory. We only noted one stroke and found no other thromboembolic complications. No aortic valve damage was observed in the study cohort. Finally, seven patients (15.2 %) had pump thrombosis, and nine (19.6 %) underwent device exchange. Sixteen patients (34.8 %) suffered from bleeding requiring transfusions during the whole treatment course. In ten patients (21.7%), the inflow cannula dislocated into the aortic root. The first version of the Impella 5.5 presents promising early outcomes for patients with acute heart failure and expands the spectrum of available devices. The adverse event profile is favorable for short-term devices. Dislocations have been addressed by design changes. With increasing experience with this device, our study suggests that the indications for use will expand to other cardiac shock etiologies and may improve myocardial recovery and survival in patients with cardiogenic shock.

Multi-constituent simulation of thrombus formation at LVAD inlet cannula connection: Importance of Virchow's triad.

As pump thrombosis is reduced in current-generation ventricular assist devices (VAD), adverse events such as bleeding or stroke remain at unacceptable rates. Thrombosis around the VAD inlet cannula (IC) has been highlighted as a possible source of stroke events. Recent computational fluid dynamics (CFD) studies have attempted to characterize the thrombosis risk of different IC-ventricle configurations. However, purely CFD simulations relate thrombosis risk to ad hoc criteria based on flow characteristics, with little consideration of biochemical factors. This study investigates the genesis of IC thrombosis including two elements of the Virchow's triad: endothelial injury and hypercoagulability. To this end a multi-scale thrombosis simulation that includes platelet activity and coagulation reactions was performed. Our results show significant thrombin formation in stagnation regions (|u| < 0.005m/s) close to the IC wall. In addition, high shear-mediated platelet activation was observed over the leading-edge tip of the cannula. The current study reveals the importance of biochemical factors to the genesis of thrombosis at the ventricular-cannula junction in a perioperative state. This study is a first step toward the long-term objective of including clinically relevant pharmacological kinetics such as heparin or aspirin in simulations of inflow cannula thrombosis.

Acoustic Properties of Axial and Centrifugal Flow Left Ventricular Assist Devices and Prediction of Pump Thrombosis

ObjectiveTo characterize the properties of the audible tones produced by current left ventricular assist device (LVAD) pumps approved for use, and to ascertain if changes in those may be present in the setting of pump thrombosis. Patients and MethodsFrom August 31, 2016, to January 16, 2020, LVAD recipients consented to have surface recordings obtained using a high-fidelity digital stethoscope. Audio data were analyzed using digital recording and editing software to produce an acoustic spectrogram by Fast Fourier transformation. ResultsRecordings were obtained in 53 patient encounters (27 HeartMate II, 19 HeartWare and 7 HeartMate 3). In 12 patients (9 HeartMate II, 3 HeartWare) there was a clinical concern for pump thrombosis. In all patients and pump models, a fundamental frequency was noted, and the second and third harmonics were also clearly detectable. Where thrombosis occurred in the HeartMate II pump, the absolute (normal -46.9 [-57.5,-42.9] dB vs thrombosis -41.4 [-49.8,-26.8] dB; P=.08) and relative (normal 0.72 [0.62, 0.92] vs thrombosis 0.95 [0.86, 1.24]; P=.01) third harmonic frequencies were increased in amplitude. Where paired data were available, an increase in the absolute and relative third harmonic frequencies was observed in all patients. In the case of the HeartWare device, a consistent difference in harmonic amplitudes in the setting of thrombosis could not be identified. ConclusionA consistent pattern of fundamental and harmonic frequencies is common to all LVADs currently approved for use. Alterations in the amplitude of higher order harmonics may signal the onset of pump thrombosis in axial flow LVADs.

Optimal Bridging Strategy Post-Ventricular Assist Device Implantation Remains Unclear.

To the Editor: It was with enthusiasm that we read the article by Bates et al. describing bivalirudin utilization in a heterogeneous ventricular assist device (VAD) population.1 We were concerned, however, regarding their argument for the potential of bivalirudin as an initial bridging agent post-device implantation. No patients in their cohort received bivalirudin in this setting without being transitioned from either warfarin or heparin for either suspected or confirmed thrombosis or heparin-induced thrombocytopenia. Furthermore, the median time from VAD insertion to initiation of bivalirudin in their study was 116 days. Although we recognize the potential benefits of direct thrombin inhibitor therapy in the scenarios described within their cohort, the evidence for use of bivalirudin during the immediate postimplantation period as a bridge to oral anticoagulation is not well-elucidated. We have published the largest series to date of bivalirudin bridged patients (35) to oral anticoagulation after VAD placement.2 In our analysis, three different strategies were compared: bivalirudin, heparin, and no bridging immediately after VAD implantation. Our results suggested that bivalirudin was no different compared with heparin or no anticoagulation in terms of both thrombotic complications and bleeding events within 30 days of VAD implantation when controlling for international normalized ratio (INR) goals. In addition, the cost of heparin therapy was more than 40 times less than bivalirudin, although with the generic introduction of bivalirudin since the publication of our research, this number has certainly diminished. Overall, neither the Bates et al. data nor ours is sufficient to appropriately answer the question of which strategy is optimal to utilize post-VAD implantation.1,2 In addition, as the authors suggest, device type may also influence the benefits or weaknesses of various anticoagulant therapies. With the dramatic reduction in the rate of suspected of confirmed pump thrombosis observed in MOMENTUM-3, it is unclear if benefits observed in patients with older generation devices will translate to benefits in patients with the HeartMate 3.3 A large randomized trial, although welcome, is unlikely to be undertaken leaving a gap in the literature, which has yet to be filled for over a decade. Statements, however, on the utility of an approach without conclusive data, such as the use of bivalirudin in the post-implant period, and with some evidence showing that it has no discernable benefit should be made cautiously, if at all.

Early Pump Thrombosis Detection Algorithm in Patients Implanted with Heartware Pump

<h3>Purpose</h3> Continuous-flow left ventricular assist devices (CF-LVADs) have been extensively used in a strategy of bridge to orthotopic heart transplant due to increasing number of patients with end-stage heart failure and worldwide shortage of heart donors. However, usage of CF-LVADs is not free from limitations such as device-related adverse events, including pump thrombosis (PT). The purpose of this study was to develop an early PT detection algorithm based on the basic parameters monitored by the implanted device. <h3>Methods</h3> We analyzed the power consumption recorded by pump controller, normalized with respect to impeller speed. The signal was transformed to Open-High-Low-Close form with the averaging window of 4 hours, which enabled calculation of Typical Price (TP) technical indicator. We then developed an algorithm that learns patient's usual TP values over two consecutive days. Later such an algorithm was able to analyze each subsequent data point and indicate whether the probability of thrombotic event meets predetermined threshold. <h3>Results</h3> We retrospectively reviewed log files of 101 patients implanted with HeartWare pump (HVAD). Seventeen had suspected or confirmed PT (21 events) according to INTERMACS definitions. Our algorithm classified correctly all cases with 100% sensitivity and 100% specificity. Based on abnormally high power consumption (Fig 1A) and TP evaluation, the algorithm alerted at least 40% probability of pump thrombosis (Fig 1B) preceding the onset of PT by 5.4 days on average. In the worst-case scenario, the threshold was reached 16 hours prior to the event. <h3>Conclusion</h3> Our study shows that it is possible to predict PT events with use of a dedicated, custom-made algorithm. Automatic event detection and alarming could enable earlier medical management of PT and improve prognosis in patients implanted with HVAD.

Case of Outflow Graft Obstruction from Extrinsic Compression in HM III LVAD

<h3>Introduction</h3> Pump thrombosis is an important adverse outcome to be aware of in patients with left ventricular assist devices (LVADs). While Heart Mate III (HMIII) has significantly lower rates of pump thrombosis, outflow graft obstruction remains a possibility. We present a case of outflow graft obstruction secondary to extrinsic compression at the site of the bend relief in a HMIII. <h3>Case Report</h3> A 36-year-old male with a history of non-ischemic cardiomyopathy status post HMIII as a bridge to transplant, with history of two LVAD pump exchanges due to pump thrombosis, presented with dyspnea and low flow alarms. Computed tomography (CT) of the chest demonstrated luminal narrowing with near obstruction of the outflow graft, concerning for thrombus. Urgent right heart catheterization demonstrated cardiogenic shock with elevated biventricular filling pressures. He was placed on Veno-Arterial Extracorporeal Membrane Oxygenation support and his listing status was upgraded to Status 1 for heart transplant. He was started on intravenous heparin for suspected pump thrombosis, and ultimately went on to transplant. With removal of the LVAD intra-operatively, proteinaceous material was noted between the bend relief collar and the outflow graft, leading to extrinsic compression of the graft, with no evidence of thrombus. <h3>Summary</h3> When evaluating patients with suspected outflow graft obstruction, it is important to consider not only pump thrombosis, but also the possibility of extrinsic compression of the outflow graft leading to obstruction. Distinguishing these etiologies is important as management may greatly vary.

Impact of Using a Low Anti-Xa Target Heparin Protocol on Hemocompatibility-Related Outcomes after Implantation of a HeartMate 3 Device

Purpose To evaluate early hemocompatibility-related outcomes after implementation of a low anti-Xa target heparin protocol following implantation of the HeartMate 3 Left Ventricular Assist Device (LVAD). Methods We reviewed hemocompatibility-related outcomes including mediastinal bleeding, gastrointestinal bleeding (GIB), stroke, and pump thrombosis (PT) events in recipients of HeartMate 3 LVADs before and after implementation of a low anti-Xa target heparin protocol. The higher anti-Xa protocol targeted levels of 0.3-0.5 IU/ml using a starting dose of 18 units/kg/hr with a maximum starting dose of 1530 units/hr, and the lower anti-Xa protocol targeted levels of 0.1-0.3 IU/ml using a starting dose of 7 units/kg/hr with a maximum starting dose of 595 units/hr. Results Between 9/2018 and 8/2020, 152 patients were implanted with a HeartMate 3. Mean patient age was 57 ± 12 years, 74% were males, and 76% of patients were African American. Per our center's protocol, IV heparin was started on postoperative day 5. 106 patients were treated with the higher anti-Xa protocol and 21 patients were treated with the lower anti-Xa protocol. The patients treated with the higher anti-Xa target protocol experienced 10 (9.4%) post-operative mediastinal bleeding events requiring return to the operating room (OR) while patients on the lower anti-Xa protocol experienced none. Patients treated with the higher anti-Xa target protocol experienced 8 (7.5%) GIB events within 60 days of implant while patients on the lower anti-Xa protocol experienced no GIB. Patients treated with the higher anti-Xa protocol experienced one hemorrhagic stroke and no ischemic strokes, while patients on the lower anti-Xa protocol experienced one ischemic stroke and no hemorrhagic strokes. No PT events requiring pump exchange occurred in either group. Conclusion Implementation of a low anti-Xa target heparin protocol after HeartMate 3 LVAD implantation surgery was associated with a lower incidence of mediastinal and GI bleeding. No PT events requiring pump exchange were observed in either group. Stroke rate was low in both groups. Further research is needed to determine the safest and most effective anticoagulation protocol after HeartMate 3 implantation that lowers the incidence of early hemocompatibility-related events.

Safety of Direct Oral Anticoagulants in Left Ventricular Assist Device Patients

<h3>Purpose</h3> Left ventricular assist devices (LVAD) are standard of care for management of end-stage heart failure. LVAD patients are on antiplatelet agents and long-term anticoagulation with warfarin to prevent thrombotic events. The ease of use, superior efficacy, and improved side effect profile have made direct oral anticoagulants (DOACs) the preferable anticoagulant for treatment of atrial fibrillation; but there is limited data regarding their safety and efficacy in patients with an LVAD. <h3>Methods</h3> In this multicenter retrospective analysis, LVAD patients who were switched to a DOAC after a trial of warfarin were compared to patients who remained on warfarin. The DOAC group included patients with a history of warfarin failure or noncompliance. Overall survival as well as thrombotic events (i.e. ischemic stroke, pump thrombosis) and bleeding events (i.e. intracranial or gastrointestinal (GI) bleed) were compared between the two groups. Non-parametric and semi-parametric cox multiple regression analysis were performed. Univariate screening was performed to identify co-variates to be included in the multivariable analysis when applicable. <h3>Results</h3> A total of 268 patients were included in the study (DOAC group: N=8, mean age=58±19 years, 75% male vs warfarin group: N=260, mean age=57±13 years, 81% male). The majority of the DOAC (75%) and all warfarin patients were on low-dose aspirin. There was no significant difference in mortality between the two groups (HR=2.0, P=0.2; adjusted HR=2.3, P=0.1) (Figure 1A). There were no statistically significant differences in GI bleeding (HR=0.95, P=0.9; adjusted HR=1.1, P=0.9) and intracranial bleed (HR=1.5, P=0.7) (Figure 1B-C). Additionally, the rate of ischemic stroke (HR=1.5, P=0.7) and pump thrombosis were similar between the two groups (HR=0.9, P=0.9; adjusted HR=0.7, P=0.7) (Figure 1D-E). <h3>Conclusion</h3> Our findings suggest DOACs may provide a safe and effective alternative to warfarin in the life long anticoagulation of LVAD patients. Further studies are warranted.

Left Ventricular Assist Device Exchange to HeartMate III Using Minimally Invasive Approach

<h3>Purpose</h3> Pump thrombosis, infection or device malfunction are major complications of LVAD that may need to be treated with pump exchange. There is limited data on exchanges to HMIII. Our purpose was to review outcomes of patients undergoing any LVAD to HMIII exchange at our center using minimally invasive approach (subcostal and/or left anterolateral thoracotomy). <h3>Methods</h3> We retrospectively reviewed records of patients undergoing any LVAD to HMIII exchange from January 2016 to October 2020. Pre-operative characteristics, indication, hospitalization course and post discharge data was collected. <h3>Results</h3> Ten patients underwent LVAD (7 HMII, 2 HMIII, 1 HeartWare) to HMIII exchange. Baseline characteristics are described in Table 1. Indications for exchange were pump thrombosis (3), infection + thrombosis (2), malposition (1), malposition + thrombosis (1), outflow graft obstruction from external compression (1), outflow graft twisting and thrombosis (1) and drive line injury (1). All patients underwent minimally invasive approach but 5 needed additional sternotomy to clear abscess collection or due to anatomical complexity. Post exchange, 1 patient needed pericardial window, 1 needed short term hemodialysis, 1 had recurrence of GI bleeding, 1 had CVA on POD 1 and 3 patients needed washout and debridement or hematoma evacuation. There was no change in RV function. Mean length of stay was 20.8 ±2 days. There was only 1 re-admission (sternal wound drainage needing debridement) within 30 days of discharge. There were a total of 8 other admissions (2 for MSSA Bacteremia, 1 for HF exacerbation, 1 for GI bleeding, 1 repeat debridement of sternal wound, 1 for renal failure and 2 for unrelated reasons) within 1 year post discharge. There was no recurrence of thrombosis. Mortality was 0% at 30 days and 0% at 1 year for 5/10 patients (others are alive and less than 1 year from exchange). <h3>Conclusion</h3> LVAD to HMIII exchange with a minimally invasive approach has low surgical mortality and acceptable intermediate- term outcomes.

Heart* to Heart*: Thrombosed HeartWare LVAD Exchanged to a Heartmate 3 LVAD

<h3>Introduction</h3> Left ventricular assist devices (LVADs) have undergone technological advances over the past several years, however, device thrombosis remains a feared complication. We present a case of a HeartWare HVAD presenting with pump thrombosis which failed medical therapy and was exchanged for an Abbott HeartMate 3 pump. <h3>Case Report</h3> The patient is a 38-year-old male with end stage-systolic heart failure due to a HIV associated cardiomyopathy who underwent HVAD implantation six years prior to presentation. The patient was in his usual state of health when he presented to the hospital due to a "high watt" alarm. He was asymptomatic. The patient, who was maintained on aspirin and warfarin, had a presenting INR which was subtherapeutic (1.2). Interrogation of the device logs showed an abrupt increase in power up to 9W with flows >10 L/min (baseline ∼4.5W and ∼5.5 L/min) (Figure). Computed tomography (CT) angiogram did not reveal an outflow graft thrombosis but did note pulmonary edema. The patient was diagnosed with pump thrombosis and was initially treated with two doses of alteplase 20 mg (Figure arrows). The power and flow normalized. Multiple lactate dehydrogenase (LDH) specimens were hemolyzed, but the LDH 3 days after admission ultimately was 3,550 U/L (baseline 268 U/L). Two days later, power spikes recurred. The patient was given one dose of alteplase 50 mg without success. The patient underwent emergent exchange to a HeartMate 3 LVAD via a re-do sternotomy. Surgery was notable for the epicardial ring of the HVAD being firmly incorporated at the left ventricular apex. To minimize trauma, the epicardial ring of the HeartMate 3 was sutured directly onto the epicardial ring of the HVAD. The Heartmate 3 was then inserted through both epicardial rings while the outflow graft was anastomosed to the remnant outflow graft of the HVAD. The patient did well post-operatively and was discharged on post-operative day number 15. <h3>Summary</h3> A thrombosed HVAD can be successfully managed with exchange to a HeartMate 3 LVAD.

Destination LVAD Therapy in African American (AA) Recipients: A Single Center Experience

Purpose Despite the approval of LVADs as destination therapy (DT) nearly 2 decades ago, significant knowledge gaps remain regarding the characteristics and outcomes of AA patients (pts) who receive LVAD therapy as DT. The present analysis sought to assess the characteristics and outcomes of DT LVAD AA pts. Methods Single center retrospective review of DT LVAD pts from 1/1/2009 to 12/31/2019 was performed. We compared clinical characteristics of AAs to non-AAs. Survival and hemocompatibility-related adverse event (HRAE) rates for AA pts were determined. Uni- and multivariate predictors of mortality were identified. Results 256 pts underwent DT LVAD implantation, of which 180 (70%) were AA. 63 pts received a HMII, 54 HVAD, and 63 HM3. Compared to non-AAs, AA pts were younger (AA: 57 ± 12 vs non-AA: 67 ± 9), more likely to be female (33% vs 16%) have HTN (71% vs 57%), had a higher BMI (mean BMI 30 ± 8 vs 26 ± 5), a non-ischemic cardiomyopathy (76% vs 33%), and a history of stroke/TIA (19% vs 8%). There were no significant differences between the 2 groups in terms of INTERMACS profile. Post-operatively, the AA cohort required more days of vasopressor support (9.5 ± 14 vs. 6.0 ± 6) and had a higher postoperative length of stay (32.9 ± 21.0 vs. 26.2 ± 21.9 days). Among AAs, GI bleeding was the most common HRAE (44% of patients with events per patient year, EPPY 0.55) followed by stroke (22%, EPPY 0.13) and pump thrombosis (16%, EPPY 0.13). The HM3 was associated with lowest HRAE rates (EPPY) amongst the 3 devices (GIB 0.40, stroke 0.07, and no pump thrombosis events). Overall survival among AA DT pts was 81% and 69% at 1-year and 2-years. 5-year survival was 41%. On univariate analysis, history of prior sternotomy (HR 1.93, 95% CI 1.03-3.59, p=0.04) and total bilirubin (HR 1.21, 95% CI 1.04-1.40, p=0.01) were predictors of AA mortality while INTERMACS profile ≥3 (HR 0.67, 95% CI 0.49-0.93, p=0.02) was associated with improved survival. Total bilirubin was the only independent predictor of mortality in multivariate analysis (HR 1.18, 95% CI 1.0-1.4, p=0.05). Conclusion AA DT LVAD pts experienced excellent 1- and 2-year survival comparable to those demonstrated in large clinical studies. HM3 implantation was associated with lower rates of GIB, pump thrombosis, and stroke. Future research focused on barriers to LVAD therapy and the quality of life of AA LVAD pts is warranted.

From Heart Failure via Biventricular Assist Device to Heart Transplantation

Purpose The Berlin Heart® EXCOR biventricular assist device (BVAD) can be used in pediatric as well as adult patients for bridge to heart transplantation (HTX). This study represents the largest population of BVAD implantations in adult patients reported so far. Methods Adult patients (>16 years) receiving a BVAD from 2006-2020 were included. Patient characteristics and outcomes were analyzed in a retrospective single center study. Results Out of the 54 patients, 45 (83%) were male, mean age of 47.4 ± 11.8 years. Mean body mass index (BMI) was 26 kg/m2 with 15 patients >30kg/m2 BMI. INTERMACS classifications were: I =23 patients (43%), II-III = 17 (31%) and IV-V= 14 (26%). Eight patients (14.8) had previous cardiac surgery before BVAD. 30% suffered from ischemic cardiomyopathy. Before BVAD 33 patients (61%) needed temporary MCS (IABP n=14, v-a ECMO n=26; with 7 patients (13%) receiving both). Mean ICU stay after BVAD was 30 days. 26 patients (48%) died on BVAD with mean time to death of 64.6 days. Causes of death were multiple organ failure (27%), septic shock (19%), cerebral hemorrhage (15%), bleeding (11%), cardiogenic shock (11%) and thrombembolic event (8%). In all 54 BVAD patients we performed 83 chamber exchanges. 28 patients were listed as high-urgency (HU) before HTX. Causes for HU-listing were VAD infections (46%, deteriorating HF under BVAD (18%), multiple VAD-related complications (14%), pump thrombosis (7%), stroke (7%), gastrointestinal bleeding (4%) and cardiac arrhythmia (4%). Complications after BVAD and HTX are listed in table 1. Mean time to HTX was 305 days. 30-day-survival after HTX was 96%. 1- and 3-year-mortality were 18 and 30% respectively. Post-HTX causes of death were cardiogenic (27%) and septic shock (36%). Conclusion These retrospective data show secondary organ failure and bleeding represented the main complications under BVAD support. Only 50% of BVAD patients were successfully transplanted but post HTX survival in BVAD patients was comparable to other HTX candidates.

Comparing HVAD Inflow Cannula Angle between Median Sternotomy and Thoracotomy

<h3>Purpose</h3> Left ventricular assist device (VAD) implantation via thoracotomy is a safe operation with potential advantages compared to conventional sternotomy. One proposed advantage is improved inflow cannula (IFC) positioning due to better visualisation. We investigated the difference in IFC angles for patients with HVADs implanted via these techniques and compared post-operative as well as long term outcomes. <h3>Methods</h3> 42 patients were retrospectively selected from our VAD database. 28 in the sternotomy group and 14 in the thoracotomy group. We included all thoracotomy implants performed at our centre and consecutive sternotomy implants from 2015-2019. Inclusion required a minimum support time of 30 days. Patients with concomitant procedures were excluded. The first post-operative CT chest scan was used to measure the angle between the IFC and mitral valve in axial and coronal planes. <h3>Results</h3> There was no significant difference in gender, INTERMACS score, BMI or age between the two groups. Median support time was not significantly different between the thoracotomy and sternotomy groups (328 vs 360 days, p=0.9). Median cardiopulmonary bypass (CPB) time was higher in the thoracotomy group (104 vs 78 minutes, p<0.01). Median ICU length of stay for the thoracotomy group was 5 days compared to 8 days in the sternotomy group, p=0.08. There was no significant difference in median IFC angle on the axial plane between the thoracotomy group and the sternotomy group (9 degrees v 10 degrees, p=0.3). Similarly, there was no difference in the coronal plane (9 degrees vs 12 degrees, p=0.9). Rates of pump thrombosis, stroke and GI bleeding were not significantly different between the two groups. <h3>Conclusion</h3> In our sample size of 42 patients, the thoracotomy group had a slightly longer CPB time, however, there was no difference in IFC angle, pump thrombosis, GI bleeding, stroke or ICU length of stay. In saying this, there may be other benefits to the thoracotomy approach such as facilitating easier sternal entry upon transplantation.

Driveline Fractures in the Heartmate II Left Ventricular Assist Device - A Single Center Experience in Asia

Purpose The incidence of driveline fractures among patients on HeartMate II Left Ventricular Assist Device (LVAD) support is reviewed Methods This is a single-center, retrospective review of all the patients on HeartMate II LVAD support who presented with driveline fractures. Patients’ presentation, interventions, and outcome following corrective treatment were examined. Results Between May 2009 and October 2018, 60 HeartMate II LVAD were implanted. Over a cumulative support period of 81 patient-years (maximum, 8.5 years), 15 patients (25%) had driveline fractures (age 14-70, 2 female), 5 of them were destination therapy (> 65 years old). Mean duration from the time of implant to driveline fractures was 44.5 ± 15.5 months. 12 patients had significant weight gain following LVAD implant, ranging from 5.2 to 32.3kg (median 17.4kg). While tethered on to power module, 8 patients (53.3%) encountered intermittent pump stoppage, 5 (33.3%) had transient low pump speed, 1 (6.7%) had recurrent driveline fault and 1 more (6.7%) presented with hemoserous discharge leaking from broken insulation in the external driveline with multiple recurrent low voltage advisory. Ungrounded cable was issued to 13 patients as a temporary measure with mean duration of its usage of 259 days (range 26-980 days), before corrective treatment. There were 2 patients with ongoing use of the ungrounded cable (mean 1 year). 8 patients (53.3%) underwent pump replacement, 2 with significant external driveline fractures successfully underwent external driveline replacement and 1 underwent heart transplant. Of the 9 pumps returned for analysis, 7 (78%) were found to have damaged internalized part of the driveline while 2 (22%) had circumferential fractures at the edge of the pump housing extending across the diameter of the bend relief. There were 3 mortality (20%), 1 due to recurrent pump pocket infection and pump thrombosis following the initial pump replacement for driveline fractures, 1 died of subdural haemorrhage before elective pump exchange and 1 died 3 weeks after pump stoppage. Conclusion The incidence of HeartMate II internal driveline fractures seemed to be higher in our Asian experience as opposed to what have been reported in literature. An ungrounded cable served as a temporary measure for short to shield and a timely pump exchange maybe lifesaving when driveline damage progressed into phase to phase.