Gastrointestinal bleeding from arteriovenous malformations in patients supported by the Jarvik 2000 axial-flow left ventricular assist device

Safety and efficacy of single-balloon enteroscopy in management of gastrointestinal bleeding in patients with a left ventricular assist device

Background and study aims Left ventricular assist devices (LVADs) are currently the standard of care in treatment of patients with end-stage heart failure waiting for heart transplant as well as destination therapy for non-transplant candidates. However, patients with LVADs are at increased risk of gastrointestinal bleeding due to the device's unique effects on hemodynamics. A major source of gastrointestinal bleeding in these patients are gastrointestinal angioectasias located within the small bowel that can only be reached with deep enteroscopy. The goal of our study was to determine the safety and efficacy of single-balloon enteroscopy (SBE) in treating gastrointestinal bleeding in patients with LVADs. Patients and methods We present a retrospective case series performed on patients with LVADs who underwent SBE to treat episodes of gastrointestinal bleeding. All procedures were performed at Emory University Hospital by a single endoscopist. Patient demographics, diagnosis and treatment of gastrointestinal bleeding, episodes of re-bleeding, and procedure-related complications were examined. Results A total of 27 SBE procedures performed in 14 patients were reviewed. SBE was performed in an antegrade approach in 89 % (24/27) of cases. Deep intubation was achieved in all antegrade procedures, with the distal jejunum reached in 79 % (19/24) of cases. The diagnostic yield was 78 %. There were no reported complications associated with the procedures. Conclusions SBE is a safe and effective modality to manage gastrointestinal bleeding in patients with LVADs.

Gastrointestinal Bleeding During the Index Hospitalization for Mechanical Circulatory Support Devices Implantation, a Nationwide Perspective

BACKGROUND

Gastrointestinal bleeding (GIB) is a common adverse event after mechanical circulatory support device implantation. However, the majority of the reported data were obtained from small single-center studies. Our aim was to study the prevalence and predictors of GIB during the index hospitalization of mechanical circulatory support devices implantation using a nationwide database.

METHODS

Nationwide inpatient sample (2009-2011) was used to perform a retrospective cross-sectional study. Adult patients with discharge diagnosis codes of congestive heart failure and procedure codes of left-ventricular assist device (LVAD) or intra-aortic balloon pump (IABP) implantation or orthotopic heart transplant (OHT, reference group) were identified. Our outcome was GIB during the index hospitalization when the device was implanted. Predictors that achieved statistical significance on the univariate analysis were included in a multivariable logistic-regression analysis.

RESULTS

A total of 87,462 patients were included, 87 % of the patients received an IABP, 6 % received LVAD, and 5 % underwent OHT. Prevalence of GIB was 8, 5, and 3 % among those who had LVAD, IABP implantation, and OHT recipients, respectively (p < 0.001). Patients who underwent LVAD implantation had twofold increase in the prevalence of GIB (OR 2.1, 1.7-2.5, p < 0.001) when using IABP or OHT groups as a reference. This increase in the prevalence was not demonstrated among IABP recipients on a multivariate level.

CONCLUSION

Prevalence of GIB was higher among LVAD compared to OHT and IABP recipients and could occur as early as the index admission of the device implantation.

Left Ventricular Assist Devices Impact Hospital Resource Utilization Without Affecting Patient Mortality in Gastrointestinal Bleeding

BACKGROUND

Left ventricular assist devices (LVADs) are being utilized for management of end-stage heart failure and require systemic anticoagulation. Gastrointestinal bleeding (GIB) is one of the most common adverse events following LVAD implantation.

AIM

To investigate the impact of continuous-flow (CF) LVAD implants on outcomes of patients admitted with GIB.

METHODS

This is a cross-sectional study utilizing the Nationwide Inpatient Sample in the CF-LVAD era from 2010 to 2012. All adult admissions with a primary diagnosis of GIB were included. Among hospitalizations with GIB, patients with (cases) and without (controls) CF-LVAD implants were compared using univariate and multivariate analyses. The main outcome measurements were in-hospital mortality, length of stay, and hospitalization costs.

RESULTS

Among 1,002,299 hospitalizations for GIB, 1112 (0.11%) patients had CF-LVADs. Bleeding angiodysplasia accounted for a majority of GIB in CF-LVAD patients (35.4% of 1112). Multivariate analysis adjusting for demographic, hospital and etiological differences, site of GIB, and patient comorbidities revealed that CF-LVADs were not adversely associated with mortality in GIB (OR 0.53, 95% CI 0.07-4.15). However, CF-LVADs independently accounted for prolonged hospitalization (3.5 days, 95% CI 2.6-4.6) and higher hospital charges ($37,032, 95% CI $7991-$66,074).

CONCLUSIONS

In patients admitted with GIB, CF-LVAD implantation accounts for higher healthcare utilization, but is not adversely associated with mortality despite therapeutic anticoagulation, increased comorbidities, and comparatively delayed endoscopy. These findings are relevant as CF-LVADs are the dominant type of LVAD and are associated with increased risk of GIB compared to their predecessors.

Angiotensin II antagonism is associated with reduced risk for gastrointestinal bleeding caused by arteriovenous malformations in patients with left ventricular assist devices

BACKGROUND

Angiogenesis is implicated in formation of gastrointestinal arteriovenous malformations (AVMs). Angiotensin II signaling is involved in angiogenesis through the vascular endothelial growth factor (VEGF) and angiopoietin-2 pathways. We hypothesized that angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) therapy would be associated with a reduced risk of all-cause gastrointestinal bleeding (GIB) and AVM-associated GIB in patients with left ventricular assist devices (LVADs).

METHODS

We reviewed records of all adult patients receiving a continuous-flow LVAD (HeartMate II or HeartWare HVAD) at Johns Hopkins Hospital between January 2004 and December 2014. Of 192 patients, 131 were included for final analyses. Logistic regression analysis adjusting for demographic, cardiovascular, and laboratory variables was used to assess the association of ACEI or ARB therapy with GIB.

RESULTS

Of 131 patients, 100 received ACEI or ARB therapy during LVAD support. Of the 31 patients who did not receive ACEI or ARB, 15 experienced GIB (48%), with 9 caused by AVMs (29%). Of 100 patients who received ACEI or ARB therapy, 24 experienced GIB (24%), with 9 caused by AVMs (9%). Logistic regression hazards model demonstrated that ACEI or ARB therapy was independently associated with a reduced risk for all-cause GIB (odds ratio 0.29, 95% confidence interval 0.12-0.72) and AVM-related GIB (odds ratio 0.23, 95% confidence interval 0.07-0.71).

CONCLUSIONS

Angiotensin II antagonism is associated with a reduced risk of AVM-related GIB in patients with LVADs. This association is independent of age, sex, blood pressure, renal function, international normalized ratio, LVAD type, and cardiomyopathy etiology.

Contraindications for video capsule endoscopy

Video capsule endoscopy (VCE) has been applied in the last 15 years in an increasing field of applications. Although many contraindications have been put into perspective, some precautions still have to be considered. Known stenosis of the gastrointestinal tract is a clear contraindication for VCE unless surgery is already scheduled or at least has been considered as an optional treatment modality. In patients with a higher incidence of stenosis, as in an established diagnosis of Crohn’s disease, clinical signs of obstruction, prior radiation or surgical small bowel resection, a preceding test with the self-dissolving patency capsule can override this contraindication. Endoscopic placement of the capsule should be considered in patients with swallowing disorders to avoid aspiration. Esophageal or gastric motility disorders may require endoscopic capsule transport or application of prokinetics if the real-time viewer proofs delayed transit. In pregnant women, VCE should be restricted to urgent cases where diagnosis cannot be postponed after delivery, as data on safety are missing. There is theoretical and clinical evidence that patients with implanted cardiac devices such as a pacemaker, cardioverters or left heart assist devices, can safely undergo VCE in spite of still existing contraindication by manufacturers. Children from the age of 2 years have safely undergone VCE. Although video capsules are not proven safe with magnetic resonance imaging (MRI), first single cases of patients incidentally undergoing MRI with an incorporated capsule have been reported, showing susceptibility artifacts but no signs of clinical harm.

Challenges faced in long term ventricular assist device support

INTRODUCTION

The development of ventricular assist device (VAD) has been one of the revolutionary advancements in end-stage heart failure management. Although the device has developed and improved significantly over the last few decades, we still face multiple challenges.

AREAS COVERED

This review will discuss quality of life, survival, and clinically encountered complications in patients with VAD support. The literature was extensively reviewed for studies describing the above topic area. We describe the impact of major challenges faced in VAD support and discuss their future and expectations. Expert commentary: The technological advancement of VADs has contributed to major improvement of overall survival, enhancement of quality of life and decrease of incidence of complications. It is expected that technologies will continue to evolve. At the same time, the indications for and timing of device implantation, and selection of device type are continuously important in clinical practice setting.

Gastrointestinal Bleeding Following LVAD Placement from Top to Bottom

BACKGROUND

Left ventricular assist devices (LVADs) are an increasingly prevalent form of mechanical support for patients with end-stage heart failure. These devices can be implanted both as a bridge to transplant and as definitive/destination therapy. Gastrointestinal (GI) bleeding is one of the most common and recalcitrant long-term complications following LVAD implantation, with an incidence approaching 30 %.

AIMS

This review will discuss what is known about the pathophysiology of GI bleeding in LVADs and the currently available options for medical and/or endoscopic management.

RESULTS

The pathophysiology of bleeding is multifactorial, with hemodynamic alterations, acquired von Willebrand factor deficiency, and coagulopathy being most often implicated. The majority of bleeding events in this population result from angioectasias and gastroduodenal erosive disease. While these bleeding events are significant and often require transfusion therapy, they are rarely life threatening. Endoscopy remains the standard of care with upper endoscopy offering the highest diagnostic yield in these patients. However, the effectiveness of endoscopic hemostasis in this population is not well established. A small number of studies have evaluated medical therapy and alterations in LVAD settings as a means of preventing or treating bleeding with variable results.

CONCLUSIONS

In summary, GI bleeding with LVADs is a common occurrence and will continue to be as more LVADs are being performed for destination therapy.

The Diagnostic Yield of Repeated Endoscopic Evaluation in Patients with Gastrointestinal Bleeding and Left Ventricular Assist Devices

INTRODUCTION

Left ventricular assist devices (LVADs) are increasingly common in patients with advanced heart failure. GI bleeding (GIB) occurs in 20-30 % of these patients and can arise anywhere in the GI tract. Given the high rates of GIB in this population, our aim was to determine the diagnostic yield of repeated endoscopic evaluation in these patients.

METHODS

We performed a retrospective review of all 257 patients who had LVADs placed between 2008 and 2013 at Duke University Hospital and identified all patients who underwent any endoscopic evaluation for GIB.

RESULTS

Of the 257 patients with LVADs placed, 78 (30 %) underwent at least one endoscopy for GIB. A source was identified in 36 % of cases, most commonly angioectasias (53.6 %). Treatment was performed in 67.9 % of patients and hemostasis was achieved in all. 64.1 % of the cohort underwent a second endoscopy for GIB. 42.9 % of these exams revealed a bleeding source. Endoscopic treatment was employed in 76.2 %. 38.5 % of the cohort underwent a third endoscopic exam for bleeding and a source was identified in 53.3 % with angioectasias remaining most common (56.3 %). By Fisher's exact and Chi-square testing, only the presence of a bleeding source (p = 0.0034) and use of hemostatic therapy (p = 0.0127) on the index examination were significantly associated with re-bleeding.

CONCLUSIONS

GIB is common in patients with LVADs. The diagnostic and therapeutic yield of endoscopy is remains high with repeated interventions. Despite these high yields, a large portion of the cohort requires repeated interventions for recurrent bleeding.

Physiologic effects of continuous-flow left ventricular assist devices

BACKGROUND

Within the past 10 years, continuous-flow left ventricular assist devices (LVADs) have replaced pulsatile-flow LVADs as the standard of care for both destination therapy and bridging patients to heart transplantation. Despite the rapid clinical adoption of continuous-flow LVADs, an understanding of the effects of continuous-flow physiology, as opposed to more natural pulsatile-flow physiology, is still evolving.

MATERIALS AND METHODS

A thorough review of the relevant scientific literature regarding the physiological and clinical effects of continuous-flow physiology was performed. These effects were analyzed on an organ system basis and include an evaluation of the cardiovascular, respiratory, hematologic, gastrointestinal, renal, hepatic, neurologic, immunologic, and endocrine systems.

RESULTS

Continuous-flow physiology is, generally speaking, well tolerated over the long term. However, several changes are manifest at the organ system level. Although many of these changes are without appreciable clinical significance, other changes, such as an increased rate of gastrointestinal bleeding, appear to be associated with continuous-flow physiology.

CONCLUSIONS

Continuous-flow LVADs confer a significant advantage over their pulsatile-flow counterparts with regard to size and durability. From a physiological standpoint, continuous-flow physiology has limited clinical effects at the organ system level. Although improved over previous generations, challenges with this technology remain. Approaching these problems with a combination of clinical and engineering solutions may be needed to achieve continued progression in the field of durable mechanical circulatory support.

Acquired von Willebrand syndrome associated with left ventricular assist device

Left ventricular assist devices (LVAD) provide cardiac support for patients with end-stage heart disease as either bridge or destination therapy, and have significantly improved the survival of these patients. Whereas earlier models were designed to mimic the human heart by producing a pulsatile flow in parallel with the patient's heart, newer devices, which are smaller and more durable, provide continuous blood flow along an axial path using an internal rotor in the blood. However, device-related hemostatic complications remain common and have negatively affected patients' recovery and quality of life. In most patients, the von Willebrand factor (VWF) rapidly loses large multimers and binds poorly to platelets and subendothelial collagen upon LVAD implantation, leading to the term acquired von Willebrand syndrome (AVWS). These changes in VWF structure and adhesive activity recover quickly upon LVAD explantation and are not observed in patients with heart transplant. The VWF defects are believed to be caused by excessive cleavage of large VWF multimers by the metalloprotease ADAMTS-13 in an LVAD-driven circulation. However, evidence that this mechanism could be the primary cause for the loss of large VWF multimers and LVAD-associated bleeding remains circumstantial. This review discusses changes in VWF reactivity found in patients on LVAD support. It specifically focuses on impacts of LVAD-related mechanical stress on VWF structural stability and adhesive reactivity in exploring multiple causes of AVWS and LVAD-associated hemostatic complications.

Gastrointestinal bleeding in a patient with a continuous-flow biventricular assist device

The association between continuous-flow left ventricular assist devices (CF-LVADs) and gastrointestinal (GI) bleeding from angiodysplasia is well recognized. However, the association between continuous-flow biventricular assist devices (CF-BIVADs) and bleeding angiodysplasia is less understood. We report a case of GI bleeding from a patient with a CF-BIVAD. The location of GI bleeding was identified by nuclear red blood cell bleeding scan. The vascular malformation leading to the bleed was identified and localized on angiography and then by pathology. The intensity of bleeding, reflected by number of units of packed red blood cells needed for normalization of hemoglobin, as well as the time to onset of bleeding after transplantation, are similar to that seen in the literature for CF-LVADs and pulsatile BIVADs. While angiography only detected a dilated late draining vein, pathology demonstrated the presence of both arterial and venous dilation in the submucosa, vascular abnormalities characteristic of a late arteriovenous malformation.

Anticoagulation management in mechanical circulatory support

Heart failure continues to be a worldwide epidemic, effecting over 23 million persons. Despite advances in medical therapy, the disease is progressive and a significant proportion of patients will need advanced heart replacement therapy. Continuous flow assist devices have become a standard approach for many patients both as a bridge to cardiac transplantation and as destination therapy (DT). However, device related complications such as bleeding and thrombosis continue to hinder further advancements of this technology. The field is rapidly advancing and efforts to reduce pump complications are directed towards improving hemocompatibility and maximizing blood flow without clinically significant hemolysis, areas of stasis or turbulent flow.

The Incidence, Predictors and Outcomes of Gastrointestinal Bleeding in Patients with Left Ventricular Assist Device (LVAD)

OBJECTIVES

To evaluate rate, recurrence, and predictors of gastrointestinal bleeding (GIB) and impact of endoscopy in left ventricular assist device (LVAD) patients.

METHODS

This is a cohort study of all patients who received the current-generation continuous-flow HeartMate II LVAD from 2005 to 2013 at our institution. Patients were followed up, and GIB events recorded until death, time of heart transplantation, or end of observation.

RESULTS

LVAD was implanted in 112 patients (median age 67 years, 88% male). A total of 44 patients (39%) had 74 GIB events occurring at a rate of 42.9 per 100 p-y. Endoscopy was performed in 77% of patients, and GIB source was identified in 57% with upper GIB found in almost two-third of cases. Right ventricular dysfunction and post-LVAD ejection fraction >30% were associated with higher GIB rates. Higher pulsatility index was associated with lower GIB rates. Re-bleeding occurred in 19 (43%) patients at a rate of 62.5 per 100 p-y and was not affected by endoscopic therapy at the index endoscopy.

CONCLUSIONS

GIB in LVAD patients is common, occurring primarily in the upper GI tract. Upper endoscopy is the preferred strategy though lower endoscopy is also recommended for a full workup. Endoscopy can identify GIB lesions in about 50% of patients, but re-bleeding is common. Right ventricular dysfunction and post-LVAD ejection fraction >30% are associated with higher GIB rates. Higher pulsatility index is associated with lower GIB rates. Reduction in pump speed is a potential strategy for managing and preventing GIB.

Pre-Operative Right Ventricular Dysfunction Is Associated With Gastrointestinal Bleeding in Patients Supported With Continuous-Flow Left Ventricular Assist Devices

OBJECTIVES

This study sought to determine whether severe right ventricular (RV) dysfunction in the pre-operative setting is associated with an increased risk of gastrointestinal bleeding (GIB) post-left ventricular assist device (LVAD).

BACKGROUND

GIB is a significant complication in patients supported with continuous-flow LVADs. The impact of RV dysfunction on the risk of GIB has not been investigated.

METHODS

We retrospectively identified 212 patients who survived index hospitalization after implantation of HeartMate II (Thoratec Corp., Pleasanton, California) or Heartware HVAD (HeartWare Corp., Framingham, Massachusetts) from June 2009 to April 2013. Patients with severe RV dysfunction on pre-LVAD echocardiogram (n = 37) were compared to patients without severe RV dysfunction (n = 175). The primary outcome was freedom from GIB.

RESULTS

The majority of patients were male (79%) with a median INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) profile of 2 at LVAD implantation. There were no significant differences between cohorts with respect to demographics, comorbidities, device type, international normalization ratio, or aspirin strategy. During follow-up, 81 patients had GIB events: 23 of 37 (62%) in the severe RV dysfunction group versus 58 of 175 (33%) in the control group (p = 0.001). After adjustment for age and ischemic cardiomyopathy, severe RV dysfunction was associated with increased risk of GIB (hazard ratio: 1.799, 95% confidence interval: 1.089 to 2.973, p = 0.022).

CONCLUSIONS

In this single-center sample of patients supported with continuous-flow LVADs, severe RV dysfunction on pre-LVAD echocardiogram was associated with an increased risk of GIB. Further studies are needed to investigate possible mechanisms by which RV dysfunction increases the risk of GIB and to identify patient populations who may benefit from alterations in antithrombotic strategies.

Late Complications Following Continuous-Flow Left Ventricular Assist Device Implantation

Left ventricular assist devices have become standard therapy for patients with end-stage heart failure. They represent potential long-term solutions for a growing public health problem. However, initial enthusiasm for this technology has been tempered by challenges posed by long-term support. This review examines these challenges and out current understanding of their etiologies.

Complications of Continuous-Flow Mechanical Circulatory Support Devices

Left ventricular assist devices (LVADs), more importantly the continuous-flow subclass, have revolutionized the medical field by improving New York Heart Association (NYHA) functional class status, quality of life, and survival rates in patients with advanced systolic heart failure. From the first pulsatile device to modern day continuous-flow devices, LVADs have continued to improve, but they are still associated with several complications. These complications include infection, bleeding, thrombosis, hemolysis, aortic valvular dysfunction, right heart failure, and ventricular arrhythmias. In this article, we aim to review these complications to understand the most appropriate approach for their prevention and to discuss the available therapeutic modalities.

Why pulsatility still matters: a review of current knowledge

Continuous-flow left ventricular assist devices (LVAD) have become standard therapy option for patients with advanced heart failure. They offer several advantages over previously used pulsatile-flow LVADs, including improved durability, less surgical trauma, higher energy efficiency, and lower thrombogenicity. These benefits translate into better survival, lower frequency of adverse events, improved quality of life, and higher functional capacity of patients. However, mounting evidence shows unanticipated consequences of continuous-flow support, such as acquired aortic valve insufficiency and acquired von Willebrand syndrome. In this review article we discuss current evidence on differences between continuous and pulsatile mechanical circulatory support, with a focus on clinical implications and potential benefits of pulsatile flow.

Gastrointestinal bleeding in recipients of the HeartWare Ventricular Assist System

OBJECTIVES

This study evaluated gastrointestinal bleeding (GIB) in patients receiving the HeartWare HVAD System (HeartWare Inc., Framingham, Massachusetts) in the pivotal BTT (Bridge to Transplant) trial and under the continued access protocol (CAP).

BACKGROUND

GIB has become a significant problem for recipients of continuous flow device left ventricular assist devices (CF-LVAD). The need for anticoagulation and antiplatelet therapies complicates the management of GIB.

METHODS

Bleeding events from 382 patients with advanced heart failure (140 patients enrolled in the BTT trial, and an additional 242 CAP patients) were analyzed. Post-implant anticoagulation consisted of heparin followed by warfarin at a target international normalized ratio of 2 to 3. Acetylsalicylic acid was recommended at 81 to 325 mg.

RESULTS

Overall, 59 of 382 (15.4%) patients experienced 108 GIB events (0.27 events per patient year). Mean time to first bleed was 273.1 days and 86.1% of events occurred beyond 30 days. Freedom from GIB was 84.1% at 1 year. Median international normalized ratio at the time of first bleed was 2.4 ± 1.4. The most common etiology of bleeding identified was arteriovenous malformation and the most common site was the small intestine. Repeat bleeding was infrequent, though GIB patients required more readmissions and developed nondevice infections more frequently. No patients required surgical intervention and no deaths directly related to GIB occurred.

CONCLUSIONS

Recipients of the HeartWare Ventricular Assist Device System had an incidence of 0.27 GIB/patient year with a freedom from GIB of 84.1% at 1 year. All patients with GIB events were managed with medical and endoscopic therapies, although 31% of patients experienced a recurrence of GIB. No surgical intervention was required. GIB did not impact survival. (Evaluation of the HeartWare Left Ventricular Assist Device for the Treatment of Advanced Heart Failure [ADVANCE]; NCT00751972).

The CentriMag centrifugal blood pump as a benchmark for in vitro testing of hemocompatibility in implantable ventricular assist devices

Implantable ventricular assist devices (VADs) have proven efficient in advanced heart failure patients as a bridge-to-transplant or destination therapy. However, VAD usage often leads to infection, bleeding, and thrombosis, side effects attributable to the damage to blood cells and plasma proteins. Measuring hemolysis alone does not provide sufficient information to understand total blood damage, and research exploring the impact of currently available pumps on a wider range of blood cell types and plasma proteins such as von Willebrand factor (vWF) is required to further our understanding of safer pump design. The extracorporeal CentriMag (Thoratec Corporation, Pleasanton, CA, USA) has a hemolysis profile within published standards of normalized index of hemolysis levels of less than 0.01 g/100 L at 100 mm Hg but the effect on leukocytes, vWF multimers, and platelets is unknown. Here, the CentriMag was tested using bovine blood (n = 15) under constant hemodynamic conditions in comparison with a static control for total blood cell counts, hemolysis, leukocyte death, vWF multimers, microparticles, platelet activation, and apoptosis. The CentriMag decreased the levels of healthy leukocytes (P < 0.006), induced leukocyte microparticles (P < 10(-5) ), and the level of high molecular weight of vWF multimers was significantly reduced in the CentriMag (P < 10(-5) ) all compared with the static treatment after 6 h in vitro testing. Despite the leukocyte damage, microparticle formation, and cleavage of vWF multimers, these results show that the CentriMag is a hemocompatible pump which could be used as a standard in blood damage assays to inform the design of new implantable blood pumps.

Features of patients with gastrointestinal bleeding after implantation of ventricular assist devices

BACKGROUND & AIMS

Ventricular assist devices (VADs) are used to treat patients with end-stage heart disease. However, patients with VADs frequently develop gastrointestinal (GI) bleeding. We investigated the incidence, etiology, and outcome of GI bleeding in patients with VADs.

METHODS

In a retrospective study, we analyzed data from 391 consecutive patients (mean age, 53.9 ± 14.2 years; 81% male) who underwent VAD implantation for end-stage heart disease from January 2000 through May 2012 at the Cleveland Clinic. Multivariable logistic regression analysis was used to identify factors independently associated with GI bleeding in patients with VADs.

RESULTS

Sixty-two patients (15.9%) had GI bleeding. The risk of GI bleeding increased by 10% for every 5-year increase in age (P = .006). GI bleeding was also associated with lower body mass index (P = .046), current smoking (P = .007), and lower baseline levels of hemoglobin (P < .001). Bleeding was primarily overt (79%), and most patients presented with hematochezia (43.5%). Causes of bleeding were primarily vascular malformations (26.5%) and ulcers (26.5%). Patients who received VADs as their only therapy, rather than as a bridge-to-transplantation, were more likely to have GI bleeding (P = .008). Colonoscopy detected GI bleeding with the highest diagnostic yield; most bleeding was associated with colonic lesions (51.4%). Overall mortality was 39.4%, and 2 deaths were directly related to GI bleeding.

CONCLUSIONS

On the basis of a large case series analysis, GI bleeding is common after implantation of VADs (15.9% of patients have at least 1 episode of bleeding). Episodes were mostly overt and predominantly from the lower GI tract; colonoscopy is the best method of detection.

Comparison of continuous-flow and pulsatile-flow left ventricular assist devices: is there an advantage to pulsatility?

BACKGROUND

Continuous-flow left ventricular assist devices (CFVAD) are currently the most widely used type of mechanical circulatory support as bridge-to-transplant and destination therapy for end-stage congestive heart failure (HF). Compared to the first generation pulsatile-flow left ventricular assist devices (PFVADs), CFVADs have demonstrated improved reliability and durability. However, CFVADs have also been associated with certain complications thought to be linked with decreased arterial pulsatility. Previous studies comparing CFVADs and PFVADs have presented conflicting results. It is important to understand the outcome differences between CFVAD and PFVAD in order to further advance the current VAD technology.

METHODS

In this review, we compared the outcomes of CFVADs and PFVADs and examined the need for arterial pulsatility for the future generation of mechanical circulatory support.

RESULTS

CVADs offer advantages of smaller size, increased reliability and durability, and subsequent improvements in survival. However, with the increasing duration of long-term support, it appears that CFVADs may have specific complications and a lower rate of left ventricular recovery associated with diminished pulsatility, increased pressure gradients on the aortic valve and decreased compliance in smaller arterial vessels. PFVAD support or pulsatility control algorithms in CFVADs could be beneficial and potentially necessary for long term support.

CONCLUSIONS

Given the relative advantages and disadvantages of CFVADs and PFVADs, the ultimate solution may lie in incorporating pulsatility into current and emerging CFVADs whilst retaining their existing benefits. Future studies examining physiologic responses, end-organ function and LV remodeling at varying degrees of pulsatility and device support levels are needed.

Does CircuLite Synergy assist device as partial ventricular support have a place in modern management of advanced heart failure?

The discrepancy between the number of patients on the waiting list and available donor hearts has led to the successful development of left ventricular assist devices (LVAD) as a bridge to transplantation. The conventional LVADs are designed to provide full hemodynamic support for the end-stage failing heart. However, full-support LVAD implantation requires major surgery, sternotomy and cardiopulmonary bypass in majority of cases. The Synergy Micro-pump is the smallest implantable LVAD and provides partial flow support up to 3 l/min. It was shown that early intervention with this device can provide substantial benefits to patients with severe heart failure not yet sick enough for a full-support LVAD. Due the small dimensions it can be implanted without cardiopulmonary bypass or a sternotomy. The purpose of this article is to review the clinical use of the Synergy Micro-pump as partial hemodynamic support.

Physiologic and hematologic concerns of rotary blood pumps: what needs to be improved?

Over the past few decades, advances in ventricular assist device (VAD) technology have provided a promising therapeutic strategy to treat heart failure patients. Despite the improved performance and encouraging clinical outcomes of the new generation of VADs based on rotary blood pumps (RBPs), their physiologic and hematologic effects are controversial. Currently, clinically available RBPs run at constant speed, which results in limited control over cardiac workload and introduces blood flow with reduced pulsatility into the circulation. In this review, we first provide an update on the new challenges of mechanical circulatory support using rotary pumps including blood trauma, increased non-surgical bleeding rate, limited cardiac unloading, vascular malformations, end-organ function, and aortic valve insufficiency. Since the non-physiologic flow characteristic of these devices is one of the main subjects of scientific debate in the literature, we next emphasize the latest research regarding the development of a pulsatile RBP. Finally, we offer an outlook for future research in the field.

Does pulsatility matter in the era of continuous-flow blood pumps?

Despite significant improved survival with continuous flow left ventricular assist devices (LVADs), complications related to aortic valve insufficiency, gastrointestinal bleeding, stroke, pump thrombosis, and hemolysis have dampened the long term success of these pumps. Evolution has favored a pulsatile heart pump to be able to deliver the maximum flow at different levels of systemic vascular resistance, confer kinetic energy to the flow of blood past areas of stenosis and generate low shear stress on blood elements. In this perspective, we suggest that lack of pulsatility may be one factor that has limited the success of continuous flow LVADs and suggest that research needs to focus on methods to generate pulsatility either by the native heart or by various speed modulation algorithms.

Mechanical circulatory support

The role for temporary and durable mechanical circulatory support is rapidly expanding. As the use of these technologies continues to grow, the emergency physician has an increasing opportunity to participate in the advancement of these potentially life-saving technologies. This review discusses the current role of the intra-aortic balloon pump in cardiogenic shock, describes the complications and management strategies for the critically ill patient with a left ventricular assist device, and explores the emerging role of ECMO in the emergency department for patients presenting in refractory cardiogenic shock and cardiac arrest.

The effects of continuous and intermittent reduced speed modes on renal and intestinal perfusion in an ovine model

The effects of the continuous-flow output on renal and intestinal microcirculation have not been extensively studied. To address this, the Heartware HVAD pump loaded with continuous and intermittent reduced speed (IRS) modes was implanted in four sheep and then operated at low and high speeds to mimic partial and complete unloading of the left ventricle. Then microsphere and positron emission tomography/computed tomography (PET/CT) studies were used to assess renal and intestinal tissue perfusion at various pump speeds and flow modes as compared with baseline (pump off). Arterial and venous oxygen (T02) and carbon dioxide (TCO2) contents were measured to assess changes in intestinal metabolism. Renal and intestinal regional blood flows did not produce any significant changes compared with baseline values in either continuous or IRS modes and speeds. The venous TO2 and TCO2 significantly increased in continuous and IRS modes and speeds compared with baseline. Our data suggested that renal and intestinal tissue perfusions were not adversely affected by continuous and IRS modes either in partial or complete unloading. Intestinal venous hyperoxia and increased TCO2 may be the evidence of intestinal arteriovenous shunting along with increased intestinal tissue metabolism. Longer-term studies are warranted in chronic heart failure models.

Left ventricular assist devices as a bridge to cardiac transplantation

Heart failure remains a significant cause of morbidity and mortality, affecting over five million patients in the United States. Continuous-flow left ventricular assist devices (LVAD) have become the standard of care for patients with end stage heart failure. This review highlights the current state of LVAD as a bridge to transplant (BTT) in patients requiring mechanical circulatory support (MCS).

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.

Association between cell-derived microparticles and adverse events in patients with nonpulsatile left ventricular assist devices

BACKGROUND

Continuous-flow left ventricular assist devices (LVADs) expose blood cells to high shear stress, potentially resulting in the production of microparticles that express phosphatidylserine (PS+) and promote coagulation and inflammation. In this prospective study, we attempted to determine whether PS+ microparticle levels correlate with clinical outcomes in LVAD-supported patients.

METHODS

We enrolled 20 patients undergoing implantation of the HeartMate II LVAD (Thoratec Corp, Pleasanton, CA) and 10 healthy controls who provided reference values for the microparticle assays. Plasma was collected before LVAD implantation, at discharge, at the 3-month follow-up, and when an adverse clinical event occurred. We quantified PS+ microparticles in the plasma using flow cytometry.

RESULTS

During the study period, 8 patients developed adverse clinical events: ventricular tachycardia storm in 1, non-ST-elevation myocardial infarction in 2, arterial thrombosis in 2, gastrointestinal bleeding in 2, and stroke in 3. Levels of PS+ microparticles were higher in patients at baseline than in healthy controls (2.11% ± 1.26% vs 0.69% ± 0.46%, p = 0.007). After LVAD implantation, patient PS+ microparticle levels increased to 2.39% ± 1.22% at discharge and then leveled to 1.97% ± 1.25% at the 3-month follow-up. Importantly, levels of PS+ microparticles were significantly higher in patients who developed an adverse event than in patients with no events (3.82% ± 1.17% vs 1.57% ± 0.59%, p < 0.001), even though the 2 patient groups did not markedly differ in other clinical and hematologic parameters.

CONCLUSIONS

Our results suggest that an elevation of PS+ microparticle levels may be associated with adverse clinical events. Thus, measuring PS+ microparticle levels in LVAD-supported patients may help identify patients at increased risk for adverse events.

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.

Evaluation and management of emergencies in patients with mechanical circulatory support devices

Mechanical circulatory support devices such as ventricular assist devices have become the approved and accepted treatment option to improve survival and quality of life in patients with advanced heart failure refractory to medical therapy. Patients as a result are living longer and presenting to emergency medical services, primary care facilities, emergency departments, and critical care units more frequently. Currently, health care providers have limited experience in managing this complex patient population. Thus, we created a standardized method of initial evaluation and algorithmic approach of management to help in the management of emergencies in this unique patient population. We present a comprehensive overview of the types of mechanical assist devices, their complications, and an algorithmic approach to the emergency management in the patients with mechanical circulatory support. A systematic method is crucial in prompt and early recognition of emergencies to ensure appropriate management of these patients.

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.

Platelet glycoprotein Ibα ectodomain shedding and non-surgical bleeding in heart failure patients supported by continuous-flow left ventricular assist devices

BACKGROUND

Non-surgical bleeding (NSB) is a major complication among heart failure (HF) patients supported by continuous-flow left ventricular assist devices (CF-LVADs). Understanding the hemostatic defects contributing to NSB after CF-LVAD implantation is crucial for prevention of this adverse event. The aim of this study was to examine the link between platelet glycoprotein Ibα (GPIbα) ectodomain shedding and NSB in CF-LVAD recipients and to identify a potential biomarker of NSB.

METHODS

Serial blood samples were collected from 35 HF patients supported with CF-LVADs. Platelet function was evaluated by a platelet function analysis device and thromboelastography (TEG). Platelet GPIbα shedding, von Willebrand factor (vWF) antigen and vWF collagen binding capacity were determined using enzyme-linked immunosorbent assays (ELISAs). The structural analysis of vWF was performed by gel electrophoresis. These platelet function measures with vWF parameters of the patients who had NSB between 4 and 32 days after CF-LVAD implantation (bleeder) were analyzed against those without NSB (non-bleeder). Blood samples from 7 healthy individuals were collected to obtain healthy reference values for the laboratory assays.

RESULTS

Elevated GPIbα shedding was found to be a pre-existing condition in all HF patients prior to CF-LVAD implantation. Post-operative level of GPIbα shedding increased and remained elevated in the bleeder group, whereas a consistent decrease was found in the non-bleeder group. A receiver operating characteristic (ROC) analysis indicated that the level of GPIbα shedding had a predictive power of NSB in patients on CF-LVAD support.

CONCLUSIONS

Platelet GPIbα ectodomain shedding which attenuates platelet reactivity is associated with NSB. Plasma GPIbα level may potentially be used to refine bleeding risk stratification in CF-LVAD patients.

Advances and future directions for mechanical circulatory support

Although cardiac transplant remains the gold standard for the treatment of end-stage heart failure, limited donor organ availability and growing numbers of eligible recipients have increased the demand for alternative therapies. Limitations of first-generation left ventricular assist devices for long-term support of patients with end-stage disease have led to the development of newer second-generation and third-generation pumps, which are smaller, have fewer moving parts, and have shown improved durability, allowing for extended support. The HeartMate II (second generation) and HeartWare (third generation) are 2 devices that have shown great promise as potential alternatives to transplantation in select patients.

Capsule Endoscopy in Patients with Implantable Electromedical Devices is Safe

Background and Study Aims. The presence of an implantable electromechanical cardiac device (IED) has long been considered a relative contraindication to the performance of video capsule endoscopy (CE). The primary aim of this study was to evaluate the safety of CE in patients with IEDs. A secondary purpose was to determine whether IEDs have any impact on images captured by CE. Patients and Methods. A retrospective chart review of all patients who had a capsule endoscopy at Mayo Clinic in Scottsdale, AZ, USA, or Rochester, MN, USA, (January 2002 to June 2010) was performed to identify CE studies done on patients with IEDs. One hundred and eighteen capsule studies performed in 108 patients with IEDs were identified and reviewed for demographic data, method of preparation, and study data. Results. The most common indications for CE were obscure gastrointestinal bleeding (77%), anemia (14%), abdominal pain (5%), celiac disease (2%), diarrhea (1%), and Crohn's disease (1%). Postprocedure assessments did not reveal any detectable alteration on the function of the IED. One patient with an ICD had a 25-minute loss of capsule imaging due to recorder defect. Two patients with LVADs had interference with capsule image acquisition. Conclusions. CE did not interfere with IED function, including PM, ICD, and/or LVAD and thus appears safe. Additionally, PM and ICD do not appear to interfere with image acquisition but LVAD may interfere with capsule images and require that capsule leads be positioned as far away as possible from the IED to assure reliable image acquisition.