Low Flow Alarms Research Articles

Left Ventricular Dimensions and Clinical Outcomes With a Fully Magnetically Levitated Left Ventricular Assist Device.

Prior analyses have suggested that a smaller left ventricular end-diastolic diameter (LVEDD) is associated with reduced survival following HeartMate 3 left ventricular assist device implantation. In this trial-based comprehensive analysis, the authors sought to examine clinical characteristics and association with the outcome of this specific relationship. The authors analyzed the presence of LVEDD<55mm among 1,921 analyzable HeartMate 3 patients within the MOMENTUM 3 (Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy With HeartMate 3) trial portfolio, on endpoints of overall survival and adverse events at 2 years. Adverse events included hemocompatibility-related (stroke, bleeding, and pump thrombosis) and non-hemocompatibility-related (right heart failure, infection) outcomes. Those with a smaller LVEDD (<55mm) (n=108) were older (age 63 ± 11 years vs 60 ± 12 years; P = 0.005), were more often female (31% vs 20%; P = 0.096), and had more ischemic cardiomyopathy (60.2% vs 42.6%; P = 0.0004) compared with the LVEDD≥55mm group (n=1,813). Death during implant hospitalization was higher (14.8 vs 5.7%; P=0.0007) and survival at 2 years was lower (63.3% vs 81.8%; HR: 1.97 [95%CI: 1.39-2.79]; P = 0.0002) in the LVEDD<55mm group. The LVEDD<55mm group experienced more deaths due to hemocompatibility-related adverse events (2.8% vs 0.6%; HR: 4.61 [95%CI: 1.29-16.45]; P = 0.018) and right heart failure, both early (0-30days; 7.4% vs 2.0%; HR: 3.70 [95%CI: 1.73-7.91]; P = 0.001) and late (>30days; 12.0 vs 4.8%; HR: 2.58 [95%CI: 1.37-4.84]; P = 0.003). Low-flow alarms rehospitalizations were higher in the LVEDD<55mm cohort (17.4 vs 8.3%; HR: 2.39 [95%CI: 1.59-3.59]; P< 0.001). Although infrequent in occurrence, smaller LVEDD (<55mm) is associated with increased risk for early and late mortality, a consequence of hemocompatibility-related and right heart failure-related deaths. Rehospitalizations due to low-flow alarms are also more frequent. (MOMENTUM 3 IDE Clinical Study Protocol [HM3™]; NCT02224755; MOMENTUM 3 Continued Access Protocol [MOMENTUM 3 CAP]; NCT02892955).

To Stent or not to stent – a Case Report on Left Ventricular assist Device outflow Graft Stenosis

Left ventricular assist devices (LVADs) have evolved from a bridge to heart transplantation to a more common destination therapy for end-stage heart failure. Complications such as outflow graft stenosis, with a reported probability of 6% at 5 years post-LVAD support, pose significant challenges. Emergent surgical decompression or cardiac transplant are typical therapies, with few reports on outflow graft stenting, none involving the BeGraft® aortic stent. A 68-year-old man with a HeartMate 3TM LVAD presented with recurrent low-flow alarms two years post-implantation. CT angiography revealed high-grade outflow graft stenosis near the ascending aorta. Intervention involved percutaneous femoral access, deployment of a BeGraft Aortic stent, and subsequent observation in the intensive care unit (ICU). Post-intervention CT angiography showed patent outflow graft, with discharge occurring after eight days without complications. Endovascular techniques offer low-risk, high-survival solutions for complex LVAD-related complications, like outflow graft stenosis. Our case highlights successful use of the BeGraft® aortic stent, offering high radial force and post-dilation options. Careful patient selection and evaluation are essential for optimal outcomes in endovascular treatment of outflow graft stenosis.

Abstract 4117646: The Ultimate Test in Hemocompatibility: HeartMate3 Restart After Prolonged Pump Shut Down

Introduction: The HeartMate 3 (HM3) LVAD, was shown to have a higher survival free of hemocompatibility related adverse events (HRAE) compared to its predecessors (HM2, HVAD). Superior HM3 outcomes are attributed to wide blood flow pathways coupled with frictionless movement and intrinsic pulsatility, reducing shear stress and blood stasis. It is unknown if improved hemocompatibility can withstand pump restart after prolonged shutdown. We herein report a case of HM3 pump stoppage without subsequent HRAE. Case Presentation: A 41-year-old male underwent HVAD implant in 2019 for advanced non-ischemic cardiomyopathy. This was exchanged to HM3 for recurrent neurological events despite therapeutic anticoagulation. Ten months after exchange, he awakened one morning to find his LVAD had been off for an unknown period but had not heard any device alarms (85dB if on battery power, 165dB if on wall power). Since he felt well he changed to battery power resulting in immediate pump restart. Log file analysis showed pump stoppage 2 am – 10 am, without preceding low flow alarms or power elevations. Management and Outcomes: In the ER INR was 1.5 (2.8 one week prior) and systemic heparin was started. Evaluation included: 1) CT brain without acute infarcts 2) echocardiogram without intracardiac thrombus 3) CT Angiography with patency of the inflow cannula and outflow graft 4) stable serial LDH measurements. The controller was exchanged, and analysis noted normal function. 1-year later the patient is maintained on warfarin and aspirin 325mg without further HRAE. Given the patient’s neurologic history and pump stoppage event, we did not invoke ARIES trial guidance and thus continued aspirin. Conclusion: Pump stoppage occurs when there is complete battery depletion, disconnection of both power leads, or the percutaneous lead from system controller. Our case is unique in that the duration of pump shutdown was 8 hours and INR subtherapeutic, without HRAE in the background of neurologic events on HVAD support. It has been previously reported that complete outflow graft thrombosis can occur shortly after LVAD decommissioning. The HM3 User Manual recommends restarting the pump immediately if off for a few minutes and using clinical judgment for longer durations due to increased risk for thromboembolic events. Our case adds to the paucity of existing data on improved hemocompatibility of the HM3 during rare circumstances of the ultimate test in hemocompatibility: complete pump shut down.

Outflow graft stenosis after left ventricular assist device implantation: the rotterdam experience

Abstract Introduction Outflow graft stenosis (OGS) has been reported in patients with the HeartMate 3 left ventricular assist device (LVAD) as a result of biodebris accumulation outside the graft. As a result, patients may experience unexpected low-flow alarms, relapse of heart failure symptoms, cardiogenic shock, or even death. Different cutoff values are used to define OGS, and the literature also lacks clarity regarding how the severity of OGS relates to potential clinical outcomes. Purpose The purpose of this study is to describe the prevalence, clinical presentation, outcomes, and treatments associated with different degrees of HeartMate 3 LVAD OGS. Methods In this single-centre retrospective cohort study, we reviewed all HeartMate 3 patients between March 2016 and December 2023 with an available computed tomographic angiogram (CTA) sufficient to assess the outflow graft lumen. Before 2022, CTAs were conducted only at baseline after LVAD implantation and on specific indications, such as low-flow alarms. However, since 2022, routine biennial CTAs have been performed for all patients, starting 2 years post-LVAD implantation, reflecting increased awareness of LVAD OGS. We determined the percentage of lumen narrowing by measuring perpendicular to the outflow graft in different axes, categorizing as: no stenosis (0-25%), mild stenosis (25-50%), moderate stenosis (50-75%), and severe stenosis (&amp;gt;75%). Results We included 135 patients (median age: 53 years, 63% male), with a total of 330 available CTA scans. Throughout the study period (median FU of 31.8 months, IQR:11-43), evidence of OGS was observed in 16 (11.8%) patients: 8 (5.9%) with mild stenosis, 6 (4.4%) with moderate stenosis, and 2 (1.5%) with severe stenosis. The median time to mild stenosis, moderate stenosis, and severe stenosis was 2.5, 3.9, and 4.9 years respectively. Figure illustrates the prevalence, clinical presentation and treatment of various degrees of OGS. Among patients with mild stenosis, 75% (6/8) were detected incidentally during routine CTA scans, while 50% (3/6) of those with moderate stenosis presented with low-flow alarms. Only 7.6% (9/119) of patients with no stenosis experienced low-flow alarms. Mild and moderate stenosis were not associated with mortality compared to no stenosis (p&amp;gt;0.05), but severe stenosis was (p&amp;lt;0.05). Five patients underwent stenting, and one patient underwent surgery for outflow graft stenosis. Conclusions LVAD OGS is a significant late complication affecting approximately one in eight patients, with potentially severe consequences. Severe stenosis is associated with higher mortality compared to no stenosis. The true prevalence may be underestimated due to delayed radiological surveillance initiation. CTA plays a pivotal role as a non-invasive diagnostic step to identify OGS and systematic screening may be warranted. Endovascular stenting or surgery can effectively treat patients with OGS.

Abstract 15424: Phase-to-Phase Short Phenomenon in a Left Ventricular Assist Device: Navigating Through Clinical and Ethical Challenges

Description of Case A 59-year-old male with an axial continuous-flow left ventricular assist device (CF-LVAD) presented asymptomatically after noticing low-flow alarms. He reported extensive external driveline damage that accumulated over one year. The CF-LVAD was connected to an ungrounded cable and the driveline was repaired by the manufacturer. However, low-flow alarms continued. Log files revealed pump stoppages on all modes of power which was compatible with phase-to-phase short phenomenon (PtPSP). The patient was cannulated in case of emergent need for ECMO and upgraded to UNOS status 1 for heart transplant. Because PtPSP was considered unrepairable, the patient underwent emergent cardiac transplantation. Discussion The CF-LVAD driveline consists of three phases, each of which is formed by two electrical wires, connected to six motor stators. PtPSP causes driveline dysfunction due to a loss of insulation between the three phases owing to multiple breaches of the insulator, causing the pump to lose power when the damaged phases come into contact. Pump stoppages are likely and unpredictable even on batteries or an ungrounded cable. Patients may notice alarms associated with low flow, pump speed drops, or pump arrest. PtPSP is unrepairable, and pump exchange or urgent heart transplantation are the only viable treatment options.This case highlights the ethical complexity of the care of patients with advanced heart failure, whereby subjective treatment decisions often translate to objectively different levels of priority on the heart transplantation waiting list without intrinsic measures of disease severity, which may incentivize more aggressive care. Conclusions: CF-LVAD driveline dysfunction due to PtPSP is a clinically asymptomatic ominous scenario often uncovered by pump-controller alarms. Given the high risk of abrupt pump stoppage, a diagnosis of PtPSP necessitates emergent device exchange or explant with an orthotopic heart transplantation.

Hypercoagulability in Pediatric Autologous Hematopoietic Progenitor Cell Collection – Is it the Time to Reconsider Screening? – A Case Report

Peripheral blood hematopoietic progenitor cell harvest by apheresis in pediatric patients, a double-edged sword, has advantages and disadvantages over conventional bone marrow transplantation. The effect of granulocyte colony-stimulating factor (G-CSF) mobilization on hemostasis in literature is very scarce. A 3-year-old female child with metastatic neuroblastoma planned for autologous transplant. Following G-CSF mobilization (75 mg; 4 days), the procedure was performed with all default parameters in Spectra Optia with an acid citrate dextrose (ACD) flow rate 1:12, assuming 3-total blood volume (TBV) to be processed with 150 ml of expected collection with target yield of 6 × 106 CD34 cells/kg. Despite normal coagulation laboratory parameters, it was abandoned for reasons such as low-flow alarms and thrombi in the kit tubings. In the subsequent procedures, the ACD to whole blood ratio was decreased to 1:16, and used bolus of heparin was followed by continuous heparin infusion throughout the procedure. Despite using heparin anticoagulation, a long thrombus was aspirated at needleless port. The procedure was completed with continuous low-flow alarms. A cumulative dose of 5.67 × 106 CD34 cells/kg was achieved over four procedures, but the cause of hypercoagulability was unknown. All the coagulation parameters were within normal limits before and after the procedure. The exact cause for hypercoagulability remains elusive. There are no studies or case reports in the pediatric population on hypercoagulability following apheresis procedure after G-CSF mobilization, but evidence is available for adults, with lack of explanation. It can also be due to low draw flow from the patient side or embolization of thrombi developed in the anticoagulant unprimed site in the kit tubings. More extensive studies are required to explain the mechanism of hypercoagulability during apheresis procedures in the pediatric population.

CARC11: Outcomes of outflow graft stenting in HeartMate 3 left ventricular assist devices: A systematic review

Background: Outflow graft stenosis in continuous-flow left ventricular assist devices (CF-LVAD) is multifactorial. We sought to pool the existing evidence on indications, utilization patterns, and outcomes of transcatheter interventions for outflow graft stenosis in the HeartMate 3 (HM 3) LVAD. Methods: An electronic search was performed to identify all studies in the English literature reporting on HM 3 LVAD outflow graft stenting. Sixteen published reports and one unpublished case comprising a total of 28 patients were included. Patient-level data were extracted for analysis. Results: Median patient age was 68.5 years [Interquartile range: 58, 71] and 25.9% (7/27) were female. Dyspnea [60.7% (17/28)] was the most common presenting symptom. Low flow alarms were present in 60% (15/25) of patients, of which 20% (3/15) did not report other symptoms. LVAD findings included external compression [35.7 % (10/28)], graft twist [21.4% (6/28)], graft twist and external compression [14.3% (4.28)], intravascular thrombus [10.7% (3/28)], graft twist and intravascular thrombus [3.6% (1/28)], and pseudoaneurysm of outflow graft [3.6% (1/28)]. Median time from LVAD implantation to stenting was 2.1 years [1.4, 3] with 35.7% (10/28) receiving two stents and 14.3% (4/28) receiving >2 stents. Immediate flow normalization after stenting was observed in 85.7% (24/28). Recurrent stenosis was observed in 8% (2/25). Other complications included neurological events [8% (2/25)], recurrent low flow alarms [8% (2/25)], and severe right ventricular failure [8% (2/25)]. Heart transplantation was performed in 8% (2/25) after stenting. The 30-day mortality was 12% (3/25). Overall mortality was also 12% (3/25) at a median follow-up of 3.9 months [1, 17]. Conclusion: Outflow graft stenting in HM 3 LVAD appears to be a reasonable treatment option for outflow graft stenosis with low overall rate of complications and mortality. Further refinement of indications and approach may improve outcomes.

Durable Left Ventricular Assist Device Outflow Graft Obstructions: Clinical Characteristics and Outcomes.

We report on the clinical course and management of patients supported with durable implantable LVADs who developed outflow graft obstructions at a large academic center. We performed a retrospective review of patients receiving LVAD support from 2012 through 2020. Patients who developed an outflow graft obstruction diagnosed by computed tomography angiography (CTA) or angiogram were identified, and patient characteristics and outcomes were reported. Of the 324 patients supported by LVAD at our institution, 11 patients (3.4%) were diagnosed with outflow graft obstructions. The most common presentation was low flow alarms, which was present in 10/11 patients, and the remaining patient presented with lightheadedness. Patients had minimal LDH elevation with 8/11 presenting with less than 2-fold the upper limit of normal. Transthoracic echocardiograms were not diagnostic, but CTA enabled non-invasive diagnoses in 8/11 of the patients. Three patients with extrinsic compression of the outflow graft successfully underwent endovascular stent placement, and three patients with outflow cannula kinks received supportive care. Of the five patients diagnosed with intraluminal thromboses, one received a heart transplant, one underwent an outflow graft revision, and three received supportive care due to comorbidities. Outflow graft obstructions remain a rare, but serious complication. The true prevalence of this entity is likely underestimated due to the non-specific clinical presentation. CTA is a pivotal non-invasive diagnostic step. Patients with external compression were successfully treated with endovascular stenting.

Abstract 12777: The Lingering Snag in Era of Mechanical Pumps: A Case of Acute Pump Thrombosis Immediately After Heartmate 3 Implantation

Background: Pump thrombosis (PT) remains a dreaded complication of left ventricle assist device (LVAD) implantation. PT immediately after HeartMate 3 (HM3) implantation is rare but should be kelp in mind if early low flow alarms are noted. Case: A 57-year-old male with ischemic cardiomyopathy, Stage D heart failure (LVEF ~20%), INTERMACS category 3 on 5mcg/kg/min Dobutamine drip underwent advanced heart failure therapy evaluation and was deemed suitable candidate for LVAD implant. His ECHO showed LVIDD 6.04 cm and LV Diastolic Volume Index 122 mL. He underwent HM3 implantation via left anterior thoracotomy and upper-hemi sternotomy on 5/24/2022. Surgery was successful and the patient was taken off bypass. Pre-implant some LV trabeculations and debris were removed. However, less than 1 hour from being off bypass, the low flow alarms began which did not resolve after volume and blood pressure optimization. No RV failure was noted on TEE. Decision was made to re-open the sternum. Upon exploration, no compression of the outflow graft was noted, and inlet cannula was not mispositioned. Inspection of LVAD inlet and outlet cannula showed significant amount of white thrombus (Figure 1) and device was ultimately exchanged. Thrombus was confirmed on histopathological analysis. Post-operatively no low flow alarms were noted after pump exchange. Factor V Leiden screen and protein C activity were normal and Antithrombin 3 was falsely low (due to recent thrombus) on post-op day 1. Discussion: This is the second case of HM 3 device thrombosis within 1 hour of implant in the literature. Most of the earlier reported cases were on post-Op Day 3. The etiology of PT is unknown and further investigation is required to elucidate the same. This case will create awareness among physicians to keep PT in differentials when low flow alarms are encountered immediately post-op despite volume and BP optimization.

Successful Outflow Graft Stent Placement for a Malfunctioning Left Ventricular Assist Device

A 79-year-old man presented with hypertension and a 24-hour history of low flow alarms (flow <2.5 L/min) from his left ventricular assist device (LVAD, HeartMate II; Abbott Cardiovascular, Chicago, Illinois). At a 90-mm Hg pressure gradient, 90% stenosis of the 14-mm outflow graft tract was noted upon left heart catheterization, between the bend relief and aortic anastomosis. No standardized management has been established for graft stenosis because of technique-related challenges, including proximity of the LVAD motor to the wire, possible stent migration or slippage, and the risk of cerebral embolism.

Relapsing low-flow alarms due to suboptimal alignment of the left ventricular assist device inflow cannula.

This retrospective study investigated the correlation between the angular position of the left ventricular assist device (LVAD) inflow cannula and relapsing low-flow alarms. Medical charts were reviewed of all patients with HeartMate 3 LVAD support for relapsing low-flow alarms. A standardized protocol was created to measure the angular position with a contrast-enhanced computed tomography scan. Statistics were done using a gamma frailty model with a constant rate function. For this analysis, 48 LVAD-supported patients were included. The majority of the patients were male (79%) with a median age of 57 years and a median follow-up of 30 months (interquartile range: 19-41). Low-flow alarm(s) were experienced in 30 (63%) patients. Angulation towards the septal-lateral plane showed a significant increase in low-flow alarms over time with a constant rate function of 0.031 increase in low-flow alarms per month of follow-up per increasing degree of angulation (P = 0.048). When dividing this group using an optimal cut-off point, a significant increase in low-flow alarms was observed when the septal-lateral angulation was 28° or more (P = 0.001). Anterior-posterior and maximal inflow cannula angulation did not show a significant difference. This study showed an increasing number of low-flow alarms when the degrees of LVAD inflow cannula expand towards the septal-lateral plane. This emphasizes the importance of the LVAD inflow cannula angular position to prevent relapsing low-flow alarms with the risk of diminished quality of life and morbidity.

Cases of Surgical Intervention for Outflow Graft Obstruction Due to Accumulation of Biodebris Following HeartMate 3 Implantation

<h3>Introduction</h3> Outflow graft obstruction due to accumulation of biodebris between the outflow graft and bend relief has been reported following implantation of the HeartMate 3 (HM3) LVAD. In some instances, this can result in significant hemodynamic compromise, warranting operative intervention. We present three cases in which outflow graft obstruction was successfully relieved with operative excision of the HM3 bend relief and evacuation of biodebris. <h3>Case Report</h3> (1) 43 yr-old male with NICM s/p HM3 as bridge to transplantation presented with persistent low flow alarms at 26 months post-LVAD. CTA demonstrated outflow graft occlusion. Via subcostal incision, the patient underwent evacuation of biodebris with resolution of flow obstruction. The patient was subsequently discharged to home on postoperative day 7. (2) 38 y/o female with NICM s/p HM3 developed low flow alarms acutely during admission for GI symptoms 17 months post LVAD. CTA interpreted as "filling defect in midportion of outflow graft." The patient underwent urgent exploration via subxiphoid approach. With excision of the bed relief and evacuation of biodebris, the patient had immediate improvement in her pump flow. The patient was discharged to home on postoperative day 11. (3) 77 y/o male with NICM who underwent HM3 implantation as destination therapy. The patient presented with episodic low flow alarms 25 months post LVAD implantation. CTA demonstrated accumulation of biodebris within the course of the bend relief. The patient underwent excision and evacuation via subxiphoid approach. The patient was discharged to home on postoperative day 6. Images from CTA of the outflow graft (arrows) both pre and postoperatively are shown in Figure 1. <h3>Summary</h3> When intervention is deemed necessary, outflow graft occlusion due to accumulation of biodebris in HM3 patients can be treated surgically, with minimal morbidity. Biodebris evacuation can be effectively achieved through either a subxiphoid or subcostal approach.

Successful Thrombolytic Therapy in a Suspected Case of HeartMate 3 LVAD Thrombosis

IntroductionAlthough less common with the HeartMate 3 (HM3), pump thrombosis remains a life-threatening complication of durable left ventricular assist devices (LVAD). We present what we believe is the first case of suspected pump thrombosis in a patient with a HM3 LVAD that was successfully managed with tissue plasminogen activator (tPA).Case ReportA 22-year-old man who underwent HM3 implantation for end stage heart failure due to left ventricular non-compaction presented after experiencing two low flow alarms. His physical examination was notable for tachycardia at 125 beats per minute and an elevated Doppler mean blood pressure of 92 mm Hg. LVAD interrogation revealed low flows without power spikes (Figure 1A). Within 24 hours, he developed persistent hypotension requiring vasopressor support and multiple low flow alarms. Serial laboratory results were notable for rising LDH, peaking at 4,741 U/L and acute liver injury with AST 2,712 U/L, ALT 798 U/L and INR 5.2. Transthoracic echocardiography and computed tomography (CT) angiography did not reveal any obvious thrombus. Given this constellation of findings, pump thrombosis was suspected. Following multidisciplinary discussion, unfractionated heparin bolus and infusion were started. After an unremarkable head CT, heparin was stopped and systemic tPA was given at a dose of 5 mg over one minute followed by 10 mg over 10 minutes due to ongoing liver dysfunction. Heparin was resumed after PTT returned to therapeutic range. Immediately post tPA infusion, his LVAD flows improved from 2.3 L/min to 4.1 L/min (Figure 1B). Vasopressor support was quickly weaned. LDH, creatinine, and liver enzymes improved over the following days. Warfarin was resumed on day 14 of admission. He was discharged on aspirin, clopidogrel and warfarin.SummaryThrombolytics may be a potential therapeutic option in select cases of HM 3 pump thrombosis. Further research is warranted to delineate LVAD parameters that facilitate early recognition of pump thrombosis and successful medical management. Although less common with the HeartMate 3 (HM3), pump thrombosis remains a life-threatening complication of durable left ventricular assist devices (LVAD). We present what we believe is the first case of suspected pump thrombosis in a patient with a HM3 LVAD that was successfully managed with tissue plasminogen activator (tPA). A 22-year-old man who underwent HM3 implantation for end stage heart failure due to left ventricular non-compaction presented after experiencing two low flow alarms. His physical examination was notable for tachycardia at 125 beats per minute and an elevated Doppler mean blood pressure of 92 mm Hg. LVAD interrogation revealed low flows without power spikes (Figure 1A). Within 24 hours, he developed persistent hypotension requiring vasopressor support and multiple low flow alarms. Serial laboratory results were notable for rising LDH, peaking at 4,741 U/L and acute liver injury with AST 2,712 U/L, ALT 798 U/L and INR 5.2. Transthoracic echocardiography and computed tomography (CT) angiography did not reveal any obvious thrombus. Given this constellation of findings, pump thrombosis was suspected. Following multidisciplinary discussion, unfractionated heparin bolus and infusion were started. After an unremarkable head CT, heparin was stopped and systemic tPA was given at a dose of 5 mg over one minute followed by 10 mg over 10 minutes due to ongoing liver dysfunction. Heparin was resumed after PTT returned to therapeutic range. Immediately post tPA infusion, his LVAD flows improved from 2.3 L/min to 4.1 L/min (Figure 1B). Vasopressor support was quickly weaned. LDH, creatinine, and liver enzymes improved over the following days. Warfarin was resumed on day 14 of admission. He was discharged on aspirin, clopidogrel and warfarin. Thrombolytics may be a potential therapeutic option in select cases of HM 3 pump thrombosis. Further research is warranted to delineate LVAD parameters that facilitate early recognition of pump thrombosis and successful medical management.

Sex-Based Differences in Survival and Readmissions After Insertion of HeartMate3 (HM3) Left Ventricular Assist Device

<h3>Purpose</h3> Left ventricular assist device (LVAD) technology remains underutilized among women with advanced heart failure, likely biased by concerns for increased risk in this population. We investigated survival and cumulative incidence of readmission in LVAD patients separated by sex. <h3>Methods</h3> We retrospectively reviewed all patients who underwent HM3 LVAD implantation from 11/26/14 to 12/4/19 at a single large-volume center. All unplanned readmissions up to 900-days of follow up were analyzed. Readmissions were categorized based on INTERMACS criteria into: major bleeding, infection, arrhythmia, volume overload, device-related complications and other causes. Survival was evaluated by KM method. Incidence of all-cause readmission was evaluated using mean cumulative function method. <h3>Results</h3> Of 182 HM3 pts, 30 were women and 152 were men. Relative to women, men were more commonly white (65.1% vs 30.0%, p=0.0003), had ischemic cardiomyopathy (42.8% vs 16.7%, p=0.007) and higher baseline serum creatinine (1.45(1.2-1.8) vs 1.12(0.81-1.4)mg/dL, p<0.0001). Overall survival during index admission and at 900-days was similar (women vs men: 93.3% vs 94.1%, p=0.9; 83.3% vs 83.0%, p=0.9, respectively (<b>Figure 1A</b>). Cumulative incidence of all-cause readmissions was similar (p=0.55). Readmissions separated by etiology were also similar, except women had a greater incidence of device-related readmissions (19.7% vs 11.3%, p=0.05) (<b>Figure 1B</b>). The most common reason among device-related readmissions was low flow alarm. Median time to first readmission (p=0.56) and length of stay during index admission (p=0.66) was similar. <h3>Conclusion</h3> Women have similar survival during index admission and at 900-days of follow up. Cumulative incidence of all-cause readmission did not differ by sex, however women were more commonly admitted with device-related complications. Future investigations into the sex related LVAD outcomes is critical to avoid this treatment disparity.

“Stable” Asystole In A Patient With Left Ventricular Assist Device

The use of Left Ventricular assist devices (LVADs) for mechanical circulatory support has become a standard therapy for some patients with end-stage heart failure. Although presentation and consequences of ventricular arrhythmias (VA) in LVAD supported patients are well described and often stabilized by the mechanical support, presence of asystole is less commonly reported. Our patient is a 75-year-old male with advanced ischemic cardiomyopathy requiring cardiac resynchronization therapy-defibrillator (CRT-D) and ultimately HeartMate II LVAD. Post implantation, his CRT-D was abandoned after it reached the elective replacement indicator as he had no VAs and was not pacer dependent. He now presented with a new onset of low flow alarms that started earlier in the day. He appeared stable, pleasant and in a humorous mood. He reported lightheadedness but denied syncope. While in the ED, the patient was noted to be asystolic. His mean arterial pressure was in the 50s. Physical exam was unremarkable with the expected LVAD hum and lack of pulses. LVAD parameters revealed decreased Flow (2.5 from baseline 5.1) and Pulsatility Index (2.7 from baseline 4.9). Patient subsequently underwent implantation of a new battery with reactivation of his previously abandoned pacemaker leads with resultant hemodynamic improvement. Ultimately, he was discharged home in stable condition. Discussion: Very few cases of asystolic LVAD patients without immediate hemodynamic collapse are described. Similarly to ventricular arrhythmias, the hypothesized physiology for stability is this quasi-Fontan circulation, where low pulmonary vascular resistance with elevated central venous pressure allows pulmonary vasculature perfusion and left atrial filling. In this case, low flow alarms and decreased PI were due to decreased left ventricular preload in the setting of asystole. Ventricular arrhythmias remain common after LVAD implantation, asystole, as in the present case can equally be an issue. This is particularly true as many of LVAD supported patients have CRT-Ds implanted in the setting of pre-existent left bundle branch blocks, which can progress to complete heart block or asystole. Thus, It might not always be the case that LVAD supported patients don't benefit from maintaining ICD function. Conclusion: Traditionally unstable asystole and ventricular arrhythmia can be well tolerated in the LVAD population due to quasi-Fontan physiology. ICD role in LVAD patients is currently unclear, and should be a part of shared decision making with the patient. Yes, there may be such a thing as, "stable" asystole.

Characterizing Outflow Graft Narrowing over Time

<h3>Purpose</h3> Cases of pump dysfunction due to outflow graft (OG) anastomosis obstruction related to serous fluid accumulation have been reported but the rate of occlusion and actual frequency of asymptomatic OG diminution is not known. <h3>Methods</h3> This was a multicenter retrospective analysis of patients on HeartMate II (HMII) or HeartMate 3 (HM3) support surviving at least 180 days with at least one chest computed tomography (CT) scan at 6 months, 1, 2, and/or 3 years postoperative. Patients with OG obstruction due to torsion were excluded. The outflow graft (OG) diameter was measured at its narrowest region; region was categorized as external outflow graft (EOG), mid-graft, or within 2 cm of the aortic anastomosis. Mixed models with repeated measure linear regression was used to assess OG diameter change over time, with 14 mm as reference. Using the narrowest measure, OG diameter was modelled for freedom from death, admission for HF and low flow alarms with hazard ratio [95% CI presented]. <h3>Results</h3> Of 71 patients included herein, 25% and 75% were on HMII and HM3 support for a median [25^th, 75^th] 1230 [703,1592] days. The median CT count was 2 [1,2] per patient. At follow-up, small (1-3 mm, table), but statistically significant reductions in OG diameter were noted (Figure). The median OG narrowing was 7% [0%, 20%]. Time from device implant was the most significant contributing factor (p<0.001) while wrapping of the outflow was nonsignificantly correlated with OG narrowing (p=0.071). Device model was not correlative (p=0.16). OG diameter was not correlated with survival (HR 1.04 [0.81-1.3]), stroke (HR 0.94 [0.78-1.1]) or admissions for heart failure (HR 1.06 [0.88-1.3]), or VAD alarms (HR 0.93 [0.79-1.1]). <h3>Conclusion</h3> Minor narrowing of the OG was noted over time, irrespective of LVAD model. The observed degrees of non-twist related-OG narrowing herein did not lead to increase mortality or events. OG wrapping may be associated with OG narrowing over time. Larger sample analyses aim to define degrees of narrowing that elicit device dysfunction.

Acute Pump Thrombosis Within 1 Hour Of Heartmate 3 Implantation.

<h3>Introduction</h3> HeartMate 3 (HM3) and HeartWare (HVAD) are the most commonly used centrifugal Left ventricular assist devices (LVAD) in the current era. Pump thrombosis is a serious adverse event in LVAD patients. The earliest reported case of HM3 pump thrombosis was on the 3rd-day post-implantation. We present a rare case of pump thrombosis within the first hour of implantation. <h3>Case</h3> 39-year-old male with non-ischemic cardiomyopathy (LVEF 20-25%) was referred to our center for advanced heart failure therapies. He was transferred on milrinone 0.25 mcg/kg/min and urgent right heart catheterization was performed: RA 12, PA 46/30 with mean of 30, PCWP 30 mmHg, CO 3.17 L/min and CI 1.5 L/min/m². He was noted to be in cardiogenic shock with INTERMACS 2 profile. After multidisciplinary team discussion, urgent HM3 implantation was done. A thoracotomy and hemi-sternotomy approach was utilized. Before LVAD implantation, the LV cavity was examined and noted to be free of any clot. Heparin was reversed with standard protamine at the conclusion of cardiopulmonary bypass. No blood products or pro-coagulants were administered. Approximately 60 minutes after the end of the surgery, low flow alarms started. Intraoperative transesophageal echocardiogram was still in place and revealed no pericardial effusion or tamponade. Maneuvers including ramping speed and increasing dose of inotropes had no effect; the patient's right ventricular function was adequate, but his aortic valve could not be closed. After sternal reopening, the absence of tamponade was confirmed and there was no kinking of the outflow graft. <h3>Decision Making</h3> Given the acute persistent drop in pump flow despite the above corrective measures, there was a strong suspicion of pump thrombosis. Patient's chest was re-opened. The pump was unlocked from the sewing ring and inspected. The inflow cannula had fresh, nearly occlusive thrombus present (Figure 1). Thrombus involved all centered surfaces and also the outflow side of the pump. Pump exchange without reversal of heparin was performed. The pump was sent to the manufacturer for inspection. Histological analysis confirmed the pump thrombus. The patient's subsequent hypercoagulable workup was negative. <h3>Conclusion</h3> This case represents a unique instance of a very early pump thrombosis and should be kept in mind if new, low flow alarms are encountered immediately post-implant.

Left Ventricular Assist Device Outflow Graft Obstruction Caused by Extrinsic Compression

<h3>Introduction</h3> Left ventricular assist device (LVAD) outflow graft obstruction is a rare, but serious complication. A polytetrafluoroethylene (PTFE) graft covering has been used by some surgeons to reduce the frequency of adhesions and risk upon re-entry to the chest. Extra-luminal accumulation of material into the space between the graft and PTFE covering is one extremely rare cause of external compression and outflow graft obstruction. <h3>Case Report</h3> A 49-year-old male with a history of heart failure status post HeartWare LVAD with pump exchange one year previous due to thrombosis presented with a low flow alarm. His normal LVAD parameters were Flow 5.8 LPM, speed 3000 RPM, and power 6 Watts (W). On interrogation, he had a drop in flow to 2 LPM and power to 4 W beginning two days prior to presentation. Lab work was inconsistent with acute anemia, thrombosis, or hemolysis. Computed tomography angiography of the chest demonstrated outflow graft narrowing. He was taken to the OR for exploration which revealed accumulation of thick, proteinaceous material had accumulated between the outflow graft and the PTFE covering causing external compression and flow limiting stenosis. After removal of the external covering and relief of the obstruction, his flows increased from 2 to 6 LPM and power from to 4 to 6 W. <h3>Summary</h3> Evaluation of LVAD alarms can be difficult. Upon review of labs and imaging, an extraluminal compression of the outflow graft was suspected. LVAD outflow obstruction is a rare, but serious complication. One cause is accumulation of proteinaceous material between the semipermeable graft and the impermeable PTFE covering thought to be derived plasma contents. There is no consensus on treatment. Case series suggest percutaneous stenting or pump exchange. Surgical intervention can provide immediate relief of this problem.

Idiopathic Central Diabetes Insipidus as an Etiology of Left Ventricular Suction and Ventricular Arrhythmias

<h3>Introduction</h3> Left ventricular assist device (LVAD) implantation has increased in patients with end-stage heart failure. Left ventricular suction is a known complication of LVAD therapy, with etiologies including hypovolemia, sepsis and ventricular arrhythmias. Prompt recognition of the underlying cause is crucial in the management and prevention of suction events. <h3>Case Report</h3> A 59-year-old male with non-ischemic cardiomyopathy status post LVAD and ventricular tachycardia (VT) presented with shocks from his implantable defibrillator. He noted 2-3 weeks of low flow alarms and daily suction events with associated lightheadedness and dizziness. On admission, device interrogation revealed two episodes of successfully terminated VT. His antiarrhythmic therapy and device settings were adjusted by the electrophysiology team. On day two of hospitalization, he had ventricular fibrillation associated with a suction event. He was noted to have increased urine output despite holding diuresis. LVAD speed was decreased and he was given intravenous fluids, however right heart catheterization revealed very low filling pressures despite these interventions. He continued to have polyuria despite liberalization of fluid intake and suction alarms with associated ventricular ectopy. Urine studies revealed low urine osmolality of 266 mOsm/Kg and urine sodium of 41 mmol/L. Hypertonic saline challenge resulted in hypernatremia and improved but suboptimal urine concentration. Workup for causes of nephrogenic diabetes insipidus (DI) was unrevealing. Computed tomography of the sella did not reveal any pituitary abnormalities. He was started on desmopressin and urine output appropriately decreased. He had no further ventricular arrhythmias, though he continued to have intermittent suction alarms associated with positional changes. <h3>Summary</h3> Treatment of left ventricular suction events includes correction of underlying etiology, maintaining preload, reducing LVAD speed and management of complications including ventricular arrhythmias. Our patient's suction events and ventricular arrhythmias were presumed secondary to hypovolemia in the setting of central DI and polyuria, which improved with treatment with desmopressin. In review of literature, this is the first documented case of diabetes insipidus resulting in suction events and ventricular arrhythmias.

Cardiac Tamponade Totalis: Unique Phenomenon of Biventricular Tamponade After LVAD Implant

<h3>Introduction</h3> Cardiac tamponade results in obstructive shock due to cardiac chamber compression and impaired cardiac output. This commonly involves the RV due to its lower pressure. We report the first case of biventricular tamponade in a patient with a LVAD. <h3>Case Report</h3> A 30 yr old female (ht 4'7", wt 32 kg, BSA 1.13 m²) with inotrope dependent non-ischemic cardiomyopathy presented for heart transplant evaluation. Right heart catheterization on milrinone 0.375 mcg/kg/min was notable for RA 32 mmHg, PA 51/30 (37) mmHg, PCWP 34 mmHg, CI 1.2 L/min/m², PVR 1.8 Wood units. She was listed for cardiac transplant as her vessels were too small for percutaneous peripheral short term mechanical circulatory support. She decompensated needing VA-ECMO and then HeartWare LVAD implantation (speed 2300 RPM). 7 days post operatively, low flow alarms occurred with hypotension requiring escalating doses of ino-pressors. Echocardiography revealed a large circumferential pericardial effusion resulting in biventricular collapse (Figure A). Emergent surgical drainage was performed with 500 ml blood removal, resulting in re-expansion of both ventricles (Figure B). <h3>Summary</h3> To our knowledge this is the first report of biventricular cardiac tamponade, or as we have termed it, tamponade totalis. In the presence of a pericardial effusion, continuous LV unloading via a LVAD can cause the LV pressure to be lower than the pericardial pressure. Coupled with reduced RV preload from post-operative bleeding, this results in biventricular compression and tamponade. A combination of patient (size, anticoagulation, surgical approach) and pump (RPM) related factors likely lead to the development of tamponade totalis. Diagnosis of tamponade in a patient with a continuous flow LVAD is challenging due to similarities in presentation of right heart failure and atypical signs. Unique clues suggestive of tamponade in patients with a LVAD are respiratory variation of the pulsatilitiy index waveform and pulseless paradoxus. Imaging is key to diagnosis.