The Biological Basis of Thrombosis and Bleeding in Patients with Ventricular Assist Devices

The Role of Coagulation in Heart Failure: A Literature Review

PURPOSE OF REVIEW

This article summarizes the role of coagulation factors in the pathophysiology of heart failure including D-dimer, fibrinogen and fibrin, prothrombin, p-selectin, tissue factor, tissue plasminogen activator, von Willebrand factor, β-thromboglobulin, Factor XI, tissue thromboplastin, plasminogen activator inhibitor-1 (PAI-1), thrombomodulin, soluble urokinase-type plasminogen activator receptor (suPAR) and stuart-prower factor.

RECENT FINDINGS

The D-dimer, P-selectin, prothrombin, von Willebrand factor, tissue plasminogen activator, fibrinogen, suPAR, tissue factor, thrombomodulin and Factor XI play significant roles the pathophysiology of heart failure. However, no associations were found between β-thromboglobulin, tissue thromboplastin, PAI-1 and stuart-prower factor in the context of heart failure. Coagulation factors play significant role in the pathophysiology of heart failure. Consequently, the underlying pathophysiological mechanisms that explain changes in the cascade are closely related to the diagnostic, prognostic and therapeutic roles of coagulation cascade factors, which help physicians identify and treat heart failure.

Antithrombotic therapy for durable left ventricular assist devices - current strategies and future directions

Left ventricular assist devices (LVADs) improve survival and quality of life for patients with advanced heart failure but are associated with high rates of thromboembolic and hemorrhagic complications. Antithrombotic therapy is required following LVAD implantation, though practices vary. Identifying a therapeutic strategy that minimizes the risks of thromboembolic and hemorrhagic complications is critical to optimizing patient outcomes and is an area of active investigation. This paper reviews strategies for initiating and maintaining antithrombotic therapy in durable LVAD recipients, focusing on those with centrifugal-flow devices.

Apixaban: Alternative Anticoagulation for HeartMate 3 Ventricular Assist Device

Patients with left ventricular assist devices currently require long-term anticoagulation with warfarin. Warfarin requires frequent blood tests and is associated with adverse events when not in the therapeutic range. Apixaban is a possible alternative that is potentially better for compliance and requires no additional testing. The purpose of this study was to compare adverse events in patients with a HeartMate 3 LVAD receiving apixaban versus warfarin. Thirty-five patients underwent HM3 implantation between January 01, 2016 to January 31, 2021. The groups compared were apixaban (n = 15, 43%) and warfarin (n = 20, 57%). All patients received 325 mg aspirin daily. Stroke, bleeding, and death were identified as primary outcomes after LVAD implant. Univariate nonparametric statistical analysis was performed. The median duration of treatment with apixaban was 148 days (37-606 days). The groups were comparable in terms of age (56 vs. 54 years), gender (male, 85% vs. 75%), and renal function (Cr 1.5 vs. 1.4). The apixaban group had significantly higher mean pulmonary artery pressure (41 vs. 34, p = 0.03) and there were more (p < 0.05) ischemic cardiomyopathy and INTERMACS profile >3 in the warfarin group. At 6 months, thrombotic complications and death were not different between the groups. The two deaths in the apixaban group were from right heart failure. The apixaban group had clinically lower rates of bleeding complications (5% vs. 30%). The adverse events of bleeding, stroke, and death were similar in HM3 patients receiving warfarin or apixaban. Apixaban may be a safe alternative anticoagulant therapy in HM 3 LVAD patients.

Time in Therapeutic Range Significantly Impacts Survival and Adverse Events in Destination Therapy Patients

The study aim was to examine the impact time in therapeutic range (TTR, International Normalized Ratio [INR] 2.0-3.0) has on survival and adverse events in patients receiving the HeartWare HVAD System in the ENDURANCE and ENDURANCE Supplemental Trials. Evaluable subjects (n = 495) had >1 INR value recorded 1-24 months postimplant and were categorized as: low TTR (10-39%), moderate TTR (40-69%), and high TTR (≥70%). Baseline characteristics, adverse events, and survival were analyzed. Low TTR patients experienced higher rates of major bleeding (1.69 vs. 0.54 events per patient year [EPPY]; p < 0.001), GI bleeding (1.22 vs. 0.38 EPPY; p < 0.001), stroke (0.47 vs. 0.17 EPPY; p < 0.001), thrombus requiring exchange (0.05 vs. 0.01 EPPY; p = 0.02), infection (1.44 vs. 0.69 EPPY; p < 0.001), and renal dysfunction (0.23 vs. 0.05 EPPY; p < 0.001) compared with high TTR. Moderate TTR had higher rates of major bleeding (0.75 vs. 0.54 EPPY; p < 0.001), thrombus requiring exchange (0.05 vs. 0.01 EPPY; p = 0.007), cardiac arrhythmia (0.32 vs. 0.24 EPPY; p = 0.04), and infection (0.90 vs. 0.69 EPPY; p = 0.001) compared with high TTR. Two year survival was greater among moderate and high versus low cohorts (Log-rank p = 0.001). The significant reduction in morbidity and mortality in destination therapy (DT) HVAD patients with well-controlled TTR (≥70%) emphasizes the importance of vigilant anticoagulation management.

Contemporary outcomes of continuous-flow left ventricular assist devices-a systematic review

Background

End stage heart failure is a major cause of morbidity and mortality, and its prevalence is expected to rise with the ageing population. For suitable patients, orthotopic heart transplantation remains the gold standard therapy, however, a paucity of donor organs has led to the development of left ventricular assist devices (LVAD). These devices can be utilized as either a bridge-to-transplant (BTT) or as an alternative to heart transplantation. While these devices can prolong life and improve quality of life, they are associated with a significant number of adverse events. We aim to systematically review the literature to quantify survival and the incidence of adverse events following implantation of continuous-flow LVADs (cf-LVAD).

Methods

A systematic review was performed to determine outcomes following implantation of a cf-LVAD. Primary outcomes were survival and frequency of adverse events (such as bleeding, infection, thrombosis, stroke and right ventricular failure). Secondary outcomes included quality of life and assessment of functional status.

Results

Sixty-three studies reported clinical outcomes of 9,280 patients. Survival after cf-LVAD varied between studies. Industry-funded trials generally reported better overall survival than the single- and multi-center case series, which showed significant variation. The largest registry report documented twelve, twenty-four and forty-eight-month survival rates of 82%, 72% and 57% respectively. The most commonly reported adverse events were gastrointestinal bleeding (GIB), device-related infection, neurological events and right heart failure (RHF). Bleeding, RHF and infection were the most frequent complications experienced by those supported with cf-LVAD, occurring in up to 35%, 40% and 55% of patients, respectively. Quality of life as measured using the Kansas City Cardiomyopathy Questionnaire (KCCQ) and functional status as measured with the 6-minute walk test (6MWT) improved after cf-LVAD implantation with no decline evident two years after implantation.

Conclusions

The paucity of donor hearts has led to the development of left-ventricular assist devices as a BTT or as a destination therapy (DT). Outcomes after cf-LVAD implantation are excellent, with short-term survival comparable to heart transplantation, but long-term survival remains limited due to the incidence of post-implantation adverse events. Despite these complications, quality of life and functional status improve significantly post-implantation and remain improved over the long-term. This study demonstrates the potential benefits of cf-LVAD therapy whilst also identifying adverse events as an area of increased morbidity and mortality.

Is it Safe for Patients with Left Ventricular Assist Devices to Undergo Non-Cardiac Surgery?

Background and Objectives: Since the first use of ventricular assist devices (VADs) as bridge to recovery and bridge to cardiac transplantation in the early 1990s, significant technological advances have transformed VAD implantation into a routine destination therapy. With improved survival, many patients present for cardiac surgery for conditions not directly related to their permanent mechanical circulatory support. The aim of this study was to analyze the indications and outcomes of non-cardiac surgeries (NCSs) of left ventricular assist device (LVAD) patients in tertiary center. Material and Methods: We present a single-center experience after 151 LVAD implantations in 138 consecutive patients between 2012–2019 who had to undergo NCS during a follow-up period of 37 +/− 23.4 months on left ventricular assist device (LVAD). Results: A total of 105 procedures was performed in 63 LVAD recipients, resulting in peri-operative mortality of 3.8%. Twenty-five (39.7%) of patients underwent multiple surgeries. We found no significant difference in cumulative survival associated with the performed surgical interventions (p = 0.469). Conclusion: We demonstrated good overall clinical outcomes in LVAD patients undergoing NCS. With acceptable peri-operative mortality, NCS can be safely performed in LVAD patients on long-term support.

Platelet Mapping by Thromboelastography and Whole Blood Aggregometry in Adult Patients Supported by Mechanical Circulatory Support Device on Aspirin Therapy

Patients on mechanical circulatory support (MCS) devices are placed on aspirin and may require platelet function testing (PFT) to monitor the adequacy of therapy. Routine laboratory PFT is performed using whole blood aggregation (WBA) which typically has a long turnaround time (4-5 hours) and may not be readily available. By contrast, platelet mapping by thromboelastography (TPM) can provide results within 45 minutes. The objective of this study was to compare the results of TPM with WBA. We compared platelet mapping maximal amplitude (MA) by TPM with that of arachidonic acid (AA) to WBA with AA by impedance. We analyzed paired samples where both TPM and WBA were available. Of 45 paired samples, 34 were from 29 MCS patients and 11 were from non-MCS patients. When applying institutional interpretation guidelines with an MA_Activator cutoff of ≤40 mm, WBA_AA vs TPM MA_AA in non-MCS and MCS patients correlated well with an accuracy of 100 and 94.4%, respectively. MA_Activator >40 had poor correlation with an accuracy of 37.5%. Irrespective of MA_Activator value, TPM AA inhibition expressed in percent of inhibition had poor accuracy. When used with proper guidelines for interpretation, specifically when MA_Activator ≤ 40 mm, TPM is a suitable and reliable test to use for MCS patients on aspirin.

Speed Modulation of the HeartWare HVAD to Assess In Vitro Hemocompatibility of Pulsatile and Continuous Flow Regimes in a Rotary Blood Pump

Although rotary blood pumps (RBPs) sustain life, blood exposure to continuous supra-physiological shear stress induces adverse effects (e.g., thromboembolism); thus, pulsatile flow in RBPs represents a potential solution. The present study introduced pulsatile flow to the HeartWare HVAD using a custom-built controller and compared hemocompatibility biomarkers (i.e., platelet aggregation, concentrations for ADAMTS13, von Willebrand factor (vWf), and free-hemoglobin in plasma (pfHb), red blood cell (RBC) deformability, and RBC-nitric oxide synthase (NOS) activity) between continuous and pulsatile flow in a blood circulation loop over 5 h. The HeartWare HVAD was operated using a custom-built controller, at continuous speed (3282 rev/min) or in a pulsatile mode (mean speed = 3273 rev/min, amplitude = 430 rev/min, frequency = 1 Hz) to generate a blood flow rate of 5.0 L/min, HVAD differential pressure of 90 mm Hg for continuous flow and 92 mm Hg for pulsatile flow, and systolic and diastolic pressures of 121/80 mm Hg. For both flow regimes, the current study found; (i) ADP- and collagen-induced platelet aggregation, and ADAMTS13 concentration significantly decreased after 5 h (P < 0.01; P < 0.05), (ii) ristocetin-induced platelet aggregation significantly increased after 45 min (P < 0.05), (iii) vWf concentration did not significantly differ at any time point, (iv) pfHb significantly increased after 5 h (P < 0.01), (v) RBC deformability improved during the continuous flow regime (P < 0.05) but not during pulsatile flow, and (vi) RBC-NOS activity significantly increased during continuous flow (15 min), and pulsatile flow (5 h; P < 0.05). The current study demonstrated: (i) speed modulation does not improve hemocompatibility of the HeartWare HVAD based on no observable differences being detected for routine biomarkers, and (ii) the time-course for increased RBC-NOS activity observed during continuous flow may have improved RBC deformability.

Is there a difference in bleeding after left ventricular assist device implant: centrifugal versus axial?

BACKGROUND

Continuous-flow left ventricular assist devices (CF-LVAD) have become the standard of care for patients with end stage heart failure. Device reliability has increased, bringing the potential for VAD, compared to transplant, into debate. However, complications continue to limit VADs as first line therapy. Bleeding is a major morbidity. A debate exists as to the difference in bleeding profile between the major centrifugal and axial flow devices. We hypothesized that there would be similar adverse bleeding event profiles between the 2 major CF-LVADs.

METHODS

We retrospectively investigated isolated CF LVADs performed at our institution between July 2010 and July 2015: HeartMateII (HMII, n = 105) and HeartWare (HVAD, n = 34). We reviewed demographic, perioperative and short- and long-term outcomes.

RESULTS

There was no significant difference in demographics or comorbidities. There was a low incidence of gastrointestinal (GI) bleed 3.9% in HMII and 2.9% in HVAD (p = 0.78). Preoperatively, the cohorts did not differ in coagulation measures (p = 0.95). Within the post-operative period, there was no difference in product transfusion: red blood cells (p = 0.10), fresh frozen plasma (p = 0.19), and platelets (p = 0.89). Post-operatively, a higher but not significantly different number of HMII patients returned to the operating room for bleeding (n = 27) compared to HVAD (n = 6, p = 0.35). There was no difference in rates of stroke (p = 0.65), re-intubation (p = 0.60), driveline infection (p = 0.05), and GI bleeding (p = 0.31). The patients had equivalent ICU LOS (p = 0.86) and index hospitalization LOS (p = 0.59).

CONCLUSION

We found no difference in the rate of bleeding complications between the current commercially available axial and centrifugal flow devices.

Tolerability and Biological Effects of Long-Acting Octreotide in Patients With Continuous Flow Left Ventricular Assist Devices

Patients with implanted continuous, nonpulsatile, left ventricular assist devices (LVADs) have increased the occurrence of gastrointestinal bleeding (GIB). Although the pathophysiology is multifactorial, there are few treatments beyond supportive care. Octreotide acetate is a somatostatin analog that reduces GIB in various patient populations. However, there are sparse case series that suggest octreotide acetate may reduce GIB in LVAD patients. This 10 patient, 28 week phase I study evaluated the safety and tolerability of octreotide acetate long-acting release (LAR) 20 mg depot injection every 4 weeks until week 16 after LVAD placement. Secondary aims were occurrence of GIB and measurement of vascular endothelial growth factor, fibrinogen, von Willebrand factor, and platelet aggregation across the study period. Ten patients were enrolled, and eight completed the study. The two study dropouts were not related to octreotide. None of the patients experienced side effects or safety concerns related to octreotide nor did GIB occur in the study population. Vascular endothelial growth factor levels were maintained in the reference range throughout the duration of the study. There did appear to be laboratory evidence of acquired von Willebrand syndrome, with mildly low platelet aggregation studies. In conclusion, octreotide acetate LAR 20 mg depot injection was safe and effective in this population.

Bleeding with the artificial heart: Gastrointestinal hemorrhage in CF-LVAD patients

Continuous-flow left ventricular assist devices (CF-LVADs) have significantly improved outcomes for patients with end-stage heart failure when used as a bridge to cardiac transplantation or, more recently, as destination therapy. However, its implantations carries a risk of complications including infection, device malfunction, arrhythmias, right ventricular failure, thromboembolic disease, postoperative and nonsurgical bleeding. A significant number of left ventricular assist devices (LVAD) recipients may experience recurrent gastrointestinal hemorrhage, mainly due to combination of antiplatelet and vitamin K antagonist therapy, activation of fibrinolytic pathway, acquired von Willebrand factor deficiency, and tendency to develop small intestinal angiodysplasias due to increased rotary speed of the pump. Gastrointestinal bleeding in LVAD patients remains a source of increased morbidity including the need for blood transfusions, extended hospital stays, multiple readmissions, and overall mortality. Management of gastrointestinal bleeding in LVAD patients involves multidisciplinary approach in stabilizing the patients, addressing risk factors and performing structured endoluminal evaluation with focus on upper gastrointestinal tract including jejunum to find and eradicate culprit lesion. Medical and procedural intervention is largely successful and universal bleeding cessation occurs in transplanted patients.

Preclinical Study of Anticoagulation Regimens in Sheep After Implantation of CH-VAD Blood Pump

Effective anticoagulation regimens are needed to reduce risks of thrombosis and bleeding in animal models of ventricular assist device to verify its hemocompatibility, biologic safety and reliability. This study is to develop a validated anticoagulation procedure for a sheep model to test the newly developed CH-VAD. CH-VAD models were established in six healthy sheep by constructing blood bypass of left ventricle → ventricular assist device → descending aorta. Heparin infusion was used during operation and in the prior 4 days to maintain activated clotting time 1.5-2.0 times the baseline. From the third day, proper dosage of warfarin was used orally to maintain international normalized ratio values within the range of 1.2-2.0. After termination, we examined whether there was thrombosis in the blood pump, grafts, and anastomotic stoma. Macroscopic and histopathologic examinations were performed in major organs to check for congestion and infarction. Bleeding complications were not found in any animals throughout the experiments. Activated clotting time values were 326 ± 33 s intraoperatively and 157 ± 28 s in the prior 4 days postoperatively. Activated partial thromboplastin time values increased slowly and reached the lower limit of the target range on the fourth day. Only in one of six cases was thrombus or fibrosis tissue found in the blood flow channel of the pump. Pathologic analysis showed no thrombosis, necrosis and microembolus in end-stage organs. Under the anticoagulation regimens, coagulation system could be well controlled to avoid thrombosis and bleeding complications in sheep models for CH-VAD.

Monitoring hemostasis parameters in left ventricular assist device recipients - a preliminary report

Introduction

Mechanical circulatory support (MCS) therapy is associated with the improvement of long-term prognosis in patients with end-stage heart failure. For years it has been used as a bridge to transplant. However, more recently it is even being used as a destination therapy. Recently, clinicians have identified common MCS therapy-associated complications: pump thrombosis, bleeding, and hemolysis. These complications are very challenging with regard to both diagnosis and management.

Aim

To determine time-dependant changes of selected hemostasis/coagulation parameters in patients with end-stage heart failure treated with MCS and antithrombotic therapy.

Material and methods

Sixteen patients with end-stage heart failure on left ventricular assist device (LVAD) were followed for 6 weeks (six blood samples for each patient). Every week an extended hemostasis panel was assessed, including activated partial thromboplastin time, prothrombin time, international normalized ratio, von Willebrand factor (vWF) activity, factor VIII activity, fibrinogen level, D-dimer, platelet response to arachidonic acid (ASPI test) and adenosine diphosphate (ADP test), thrombin receptor activating peptide-6 (TRAP test) and collagen (COL test).

Results

The study population comprised 16 men. The median time from LVAD implantation was 120 days (100–150 days). During the study period the D-dimer and fibrinogen concentrations were elevated but remained similar throughout all six measurements. Meanwhile factor VIII and vWF activities were elevated in the first two measurements and then subsequently declined. Inhibition of platelet aggregation was greater early after LVAD implantation. During subsequent weeks the inhibition of platelet aggregation was less pronounced. No patient developed any bleeding or thrombo-embolic event during the study period.

Conclusions

Patients on MCS therapy demonstrate significant time-dependant changes in hemostasis parameters (both in the coagulation system and platelet aggregation).

Mechanical blood trauma in assisted circulation: sublethal RBC damage preceding hemolysis

After many decades of improvements in mechanical circulatory assist devices (CADs), blood damage remains a serious problem during support contributing to variety of adverse events, and consequently affecting patient survival and quality of life. The mechanisms of cumulative cell damage in continuous-flow blood pumps are still not fully understood despite numerous in vitro, in vivo, and in silico studies of blood trauma. Previous investigations have almost exclusively focused on lethal blood damage, namely hemolysis, which is typically negligible during normal operation of current generation CADs. The measurement of plasma free hemoglobin (plfHb) concentration to characterize hemolysis is straightforward, however sublethal trauma is more difficult to detect and quantify since no simple direct test exists. Similarly, while multiple studies have focused on thrombosis within blood pumps and accessories, sublethal blood trauma and its sequelae have yet to be adequately documented or characterized. This review summarizes the current understanding of sublethal trauma to red blood cells (RBCs) produced by exposure of blood to flow parameters and conditions similar to those within CADs. It also suggests potential strategies to reduce and/or prevent RBC sublethal damage in a clinically-relevant context, and encourages new research into this relatively uncharted territory.

Antithrombotic therapy for ventricular assist devices in children: do we really know what to do?

The use of ventricular assist devices (VADs) in children is increasing. Stroke and device-related thromboembolism remain the most feared complications associated with VAD therapy in children. The presence of a VAD causes dysregulation of hemostasis due to the presence of foreign materials and sheer forces intrinsic to the device resulting in hypercoagulability and potentially life-threatening thrombosis. The use of antithrombotic therapy in adults with VADs modulates this disruption in hemostasis, decreasing the risk of thrombosis. Yet, differences in hemostasis in children (developmental hemostasis) may result in variances in dysregulation by these devices and preclude the use of adult guidelines. Consequently, pediatric device studies must include safety and efficacy estimates of device-specific antithrombotic therapy guidelines. This review will discuss mechanisms of hemostatic dysregulation as it pertains to VADs, goals of VAD antithrombotic therapy for children and adults, and emerging antithrombotic strategies for VAD use in children.

Characteristics of gastrointestinal bleeding after placement of continuous-flow left ventricular assist device: a case series

BACKGROUND

Medical management of patients with continuous-flow left ventricular assist devices (LVADs) remains challenging for the gastroenterologist given their high risk of gastrointestinal bleeding (GIB) and need for continuous anticoagulation.

AIMS

Our aim was to better characterize LVAD patients who presented with a GIB at our facility and delineate the prevalence, presentation, time to diagnosis, management, and therapeutic endoscopic interventions, including small bowel tools that may offer additional benefit.

METHODS

We retrospectively reviewed adult patients (>18 years) who underwent LVAD implantation at our tertiary care facility between October 2011 and October 2013. Electronic medical records were reviewed for presenting symptoms, average days to initial and repeat GIB, hospital course, and techniques that led to diagnosis and hemostasis.

RESULTS

Eighteen patients underwent LVAD implantation, of which 61 % presented with a GIB for a total of 20 presentations (1.8 per patient). Mean time to initial GIB was 154 days. Patients required an average of 1.8 endoscopic procedures per admission. Esophagogastroduodenoscopy (EGD) and push enteroscopy (PE) were more likely to lead to a diagnosis, and EGD was the most commonly used diagnostic tool at initial presentation. Sixty percent of patients who initially received EGD presented with a recurrent GIB and required PE, which was diagnostic and therapeutic for small bowel angiodysplasias in 80 % of cases.

CONCLUSION

We found a higher GIB rate compared with prior studies. Bleeding events were associated with multiple procedures and interventions. We recommend an algorithmic approach to LVAD patients who bleed. Our experience suggests that PE is warranted at initial presentation in order to achieve hemostasis, prevent recurrent GIB, and decrease subsequent readmission rates.

Spontaneous hyphema and pupillary block in a patient with a left ventricular assist device

The left ventricular assist device (LVAD) has been a standard of care for the management of patients with advanced heart failure since the 1990s. An increased risk of spontaneous bleeding related to the device has been noted, ranging from minor epistaxis to major thoracic and mediastinal hemorrhages. To our knowledge, intraocular hemorrhage has not been previously reported. We report a 72-year-old patient with an LVAD who subsequently developed a spontaneous intraocular hemorrhage that manifested as hyphema, pupillary block, and acute intraocular pressure elevation.

Octreotide for the Management of Gastrointestinal Bleeding in a Patient with a HeartWare Left Ventricular Assist Device

HeartWare is a third generation left ventricular assist device (LVAD), widely used for the management of advanced heart failure patients. These devices are frequently associated with a significant risk of gastrointestinal (GI) bleeding. The data for the management of patients with LVAD presenting with GI bleeding is limited. We describe a 56-year-old lady, recipient of a HeartWare device, who experienced recurrent GI bleeding and was successfully managed with subcutaneous (SC) formulations of octreotide.

Gastrointestinal bleed after left ventricular assist device implantation: incidence, management, and prevention

BACKGROUND

Continuous-flow left ventricular assist devices (CF-LVADs) have become the standard of care for patients with end-stage heart failure (HF). While these devices have improved durability compared to earlier generation left ventricular assist devices (LVADs), increased frequency in some complications has been seen, including gastrointestinal bleeding (GIB), pump thrombosis and hemolysis. We discuss the incidence, management and prevention of GIB after CF-LVAD implantation.

METHODS

We reviewed the current literature available on the incidence, management and prevention of GIB after CF-LVAD implantation with a focus on our experience at the University of Minnesota, with data on nearly 300 patients who received a CF-LVAD from 2005 to 2013.

RESULTS

The incidence of GIB after CF-LVAD varies between 18-40% in numerous studies. At the University of Minnesota, out of 233 patients who underwent HeartMate II (HMII) implantation between 2005-2013, 60 GIB episodes occurred in 51 patients (22%), with an event rate of 0.17 gastrointestinal bleeds/patient-year of support. The etiology of GIB appears to be multifactorial. The main factors which have been identified include the need for chronic anticoagulation, acquired von Willebrand syndrome, platelet dysfunction and increased incidence of arteriovenous malformations due to chronic low pulse pressure. When managing an LVAD patient with GIB, a multi-disciplinary approach is needed. The main goals of treatment are evaluating the location and severity of the bleed, holding anti-coagulants and resuscitation to maintain stable hemodynamics.

CONCLUSIONS

GIB is a complication with considerable morbidity. Future efforts to further understand the etiology of GIB and optimize anti-coagulation are needed to improve outcomes following CF-LVAD implantation.

Gastrointestinal bleeding in patients with ventricular assist devices is highest immediately after implantation

Ventricular assist device implantation is associated with gastrointestinal bleeding (GIB); however, outcomes in terms of initial and repeat GIB risk, severity, location of lesions, and endoscopic interventions need to be better defined. Consecutive patients from a database of adult patients with ventricular assist devices (VADs) implanted between January 1, 2000, and December 31, 2010, at a single center were reviewed and followed through May 31, 2011, in a retrospective manner. The GIB events were further classified by severity, lesion location, and lesion type. Hazard analysis models were calculated for the time to GIB events. Of 166 patients with a VAD, 38 patients experienced 84 GIB events. Seventeen patients experienced ≥2 GIB events. Maximal hazard for the first bleeding event was 2.23 events/patient-year at 21 days and declined to the constant hazard by 71 days postimplantation. The hazard for recurrent GIB was greatest immediately after the first GIB event. When considering all GIB events, most lesions (68%) were located in the proximal bowel. Angiodysplasia was the most common lesion type (17.5%) seen on endoscopy when all GIB events were considered, whereas ulcers were the most common type (13.8%) seen in initial GIB events. The actuarial risk of initial GIB events peaks in the first 3 months after VAD implantation followed by a stable lower risk of bleeding. The hazard for recurrent GIB events is substantially increased immediately after the initial GIB.

General surgical complications associated with the use of long-term mechanical circulatory support devices: are we 'under-reporting' problems?

Multiple complications are associated with use of ventricular assist devices (VADs). Cardiac-related complications and infections are most frequently reported. VADs, however, can also lead to a number of general surgical complications equally significant in terms of morbidity and mortality. The authors performed a systematic literature search to review current data that specifically relate general surgical complications to patients who undergo left VAD implantation. The review provides a relatively clear understanding of the spectrum of general surgical complications and shows that they contribute significantly to morbidity and mortality in these patients.

Gastrointestinal bleeding in patients with ventricular assist devices: what every cardiac nurse should know

Patients with end-stage heart failure are increasingly being treated with implantation of a long-term ventricular assist device. As the use of these devices has grown, health care providers have been faced with managing clinically significant gastrointestinal bleeding in this population. Gastrointestinal bleeding is not uncommon and is reported to occur in 13% to 44% of patients treated with ventricular assist devices. Interestingly, because patients with ventricular assist devices are housed on units accustomed to managing the device, cardiac nurses are often asked about the management of gastrointestinal bleeding. This article describes the possible causes of, the array of diagnostic procedures for, and treatments for this complication. It is critical to develop an understanding of this topic so cardiac nurses can partner with other subspecialty groups to manage this population.

Left ventricular assist device inflow cannula thrombus: characterization with two-dimensional transthoracic echocardiography

Thrombotic complications are inherent to current generation nonpulsatile left ventricular assist devices. The clinical expression of device thrombosis ranges from catastrophic failure to protracted and indolent. We report the case of a 79-year-old patient who received a left ventricular assist device as destination therapy and presented only with vague clinical symptoms. He was found to have a large thrombus in close proximity with the inflow cannula at the left ventricular apex, raising the question of mechanical obstruction. We describe the step-by-step contrast-enhanced two-dimensional transthoracic echocardiographic examination which allowed to obtain diagnostic acoustic tomograms of the inflow cannula and obviated the need for any additional imaging modalities. Transthoracic echocardiography (TTE) is the most common imaging modality used in the clinical follow-up of left ventricular assist device recipients. A frequent clinical indication for TTE is to exclude left ventricular apical thrombus near the inflow cannula. Imaging of the inflow cannula at the left ventricular apex in the traditional apical 4 chamber, apical 2 chamber, and parasternal long axis views is challenging by TTE mainly because of poor acoustic windows, image artifacts, large body habitus, and operator experience.

Octreotide for left ventricular assist device-related gastrointestinal hemorrhage: can we stop the bleeding?

Left ventricular support devices (LVADs) are associated with a propensity toward gastrointestinal bleeding. A postulated mechanism is related to gastrointestinal arteriovenous malformations secondary to nonpulsatile flow. We describe a case of LVAD-related, gastrointestinal bleeding successfully treated with a combination of subcutaneous and intramuscular depot formulations of octreotide.

Management of patients with implanted ventricular assist devices for noncardiac surgery: a clinical review

While originally primarily used as bridge to cardiac transplantation and bridge to recovery, more commonly ventricular assist devices (VADs) are being inserted as destination therapy. These patients are being discharged from transplant and mechanical assist centers, living as outpatients, and thus the pool of community-dwelling patients with VADs continues to expand. Not infrequently they present for surgical procedures either directly related to the device itself or more often incidental to the fact that they have a VAD. This scenario may be more common in patients with VADs placed for destination therapy because these patients tend to be older and have more comorbidities and are living longer with their device. Thus, it is important for all anesthesiologists to be aware of the special anesthesia needs of patients with VADs requiring noncardiac surgery.

Rotary blood pumps as definitive treatment for severe heart failure

Rotary blood pumps are increasingly recognized as mainstream therapy for severely symptomatic heart failure. Carefully targeted refinements in patient selection and postoperative care have substantially reduced the adverse event burden. These improvements translate into better survival and quality of life in comparison with medical management. Medium-term outcomes now compete favorably with cardiac transplantation, although evidence-based outcome data indicate that transplant and ‘lifetime’ left ventricular-assist device (LVAD) candidates are fundamentally different. Significant challenges remain in relation to neurological injury and right heart failure, which may continue to limit exercise capacity. In the meantime, both physician awareness and patient access to LVAD technology remain limited. The debate is rarely between cardiac transplant or lifetime LVAD. It should focus on the choice between pump versus palliative care for the thousands of patients of all age groups who are judged ineligible for transplantation. Comprehensive healthcare systems must consider contemporary evidence and provide the most symptomatic of heart failure patients with effective care. Cardiac resynchronization therapy is no longer the ceiling for this.

Incidence and management of gastrointestinal bleeding with continuous flow assist devices

BACKGROUND

Continuous flow left ventricular assist devices (CF-LVADs) have emerged as the standard of care for patients in advanced heart failure (HF) requiring long-term mechanical circulatory support. Gastrointestinal (GI) bleeding has been frequently reported within this population.

METHODS

A retrospective analysis of 101 patients implanted with the Heart Mate II from January 2005 to August 2011 was performed to identify incidence, etiology, and management of GI bleeding. Univariate and multivariate regression analysis was conducted to identify related risk factors.

RESULTS

A significant incidence of GI bleeding (22.8%) occurred in our predominantly destination therapy (DT) (93%) population. Fifty-seven percent of the patients with bleeding episodes bled from the upper GI (UGI) tract (with 54% bleeding from gastric erosions and 37% from ulcers/angiodysplasias), whereas 35% of patients bled from the lower GI (LGI) tract. Previous history of GI bleeding (odds ratio [OR], 22.7; 95% CI, 2.2-228.6; p=0.008), elevated international normalized ratio (INR) (OR, 3.9; CI, 1.2-12.9; p=0.02), and low platelet count (OR, -0.98; CI, 0.98 -0.99; p=0.001) were independent predictors of GI hemorrhage. Recurrent bleeding was more common in older patients (mean, 70 years; p=0.01). The majority of bleeders (60%) rebled from the same site. Management strategies included temporarily withholding anticoagulation, decreasing the speed of LVADs, and using octreotide. Octreotide did not impact the amount of packed red blood cells used, rebleeding rates, length of hospital stay, or all-cause mortality. Only 1 patient died as a direct consequence of GI bleeding.

CONCLUSIONS

Multiple factors account for GI bleeding in patients on CF-VADs. A previous history of bleeding increases risk significantly and warrants careful monitoring.

Gastrointestinal bleeding with the HeartMate II left ventricular assist device

BACKGROUND

Continuous flow left ventricular assist devices (CF-LVADs) have yielded improved outcomes compared with pulsatile flow devices for patients on long-term support. However, significant rates of gastrointestinal bleeding (GIB) have been observed during CF-LVAD support.

METHODS

From March 2006 through March 2011, 86 patients with chronic heart failure underwent implantation of a CF-LVAD (HeartMate II; Thoratec Corp., Pleasanton, CA). Records were reviewed to determine the prevalence of post-implant GIB, location of the bleeding site and associated morbidity and mortality. Uni- and multivariate analyses were conducted to identify independent predictors of GIB.

RESULTS

GIB occurred in 19 patients (22.1%) with a duration of support that ranged from 5 to 456 days. Sources of GIB included small bowel and rectum in 6 patients each, large bowel in 2 patients and stomach in 1 patient. No definite source was identified in 4 patients. There were no deaths referable to GIB. Recurrent GIB occurred in 4 patients. History of a GIB prior to LVAD implant was the only variable significantly different between patients with and without post-implant GIB (21.1% vs 10.4%, p = 0.016), and was the only independent predictor of GIB (OR = 2.24, 95% CI 2.121 to 2.435, p = 0.004).

CONCLUSIONS

Gastrointestinal bleeding is a frequent source of morbidity for patients on HeartMate II LVAD support but does not significantly impact survival. As implantation of CF-LVADs with non-pulsatile flow gains popularity for both bridge-to-transplant and destination therapy, a better understanding of the pathophysiology of GIB in these patients will be needed for minimizing this complication.

Discontinuation of antithrombotic therapy for a year or more in patients with continuous-flow left ventricular assist devices

The recommended anticoagulation regimen during continuous-flow axial left ventricular assist device (LVAD) support is aspirin and warfarin with a targeted international normalized ratio of 2.0-3.0. We report two patients in whom recurrent gastrointestinal bleeding during LVAD support necessitated discontinuation of this anti-thrombotic regimen for a year or more. Despite this, neither patients developed thrombotic complications during 29 patient-months of follow-up. An acquired von Willebrand factor (VWF) abnormality reflected by the absence or decreased abundance of the highest molecular weight multimers was demonstrated in both patients. The gold standard test for platelet function, light transmission platelet aggregometry was measured in one patient and was normal, indicative that the predominant abnormality in the coagulation profile of these patients is an acquired VWF syndrome. Clinical trials are required to address the question whether it is safe to discontinue anticoagulation in LVAD patients with acquired VWF abnormalities.