In Vitro PET Imaging of a Miniature Ventricular Assist Device.

UNLABELLED: Interactions between the life-sustaining ventricular assist devices and diagnostic therapies must be carefully considered to decrease the risk of inaccurate diagnostic imaging or pump failure. METHODS: The MVAD(®) pump, currently under investigational use, was tested for interaction with radiotracers in an in vitro flow-loop study. The radiotracers (18)F-sodium fluoride and (18)F-FDG were injected into a closed loop to determine the feasibility of direct imaging of the MVAD(®) pump in a PET scanner. RESULTS: No real-time changes were observed in pump operation, and there were no statistical differences in pump parameters (power consumption, speed, and estimated flow rate) between the baseline and circulation conditions. In addition, no effect was observed on any external components, including the permissive-action-link controller and the batteries powering the device. Imaging of the internal pump components was possible, with obscuration observed only in the portion of the pump where the spinning impeller is located. Retention of radiotracer in the pump components after circulation was minimal (<1%). CONCLUSION: PET imaging is an attractive diagnostic tool for patients with a ventricular assist device and may have additional utility outside its current use, detection of infection.

Interaction of a Transapical Miniaturized Ventricular Assist Device With the Left Ventricle: Hemodynamic Evaluation and Visualization in an Isolated Heart Setup.

New left ventricular assist devices (LVADs) offer both important advantages and potential hazards. VAD development requires better and expeditious ways to identify these advantages and hazards. We validated in an isolated working heart the hemodynamic performance of an intraventricular LVAD and investigated how its outflow cannula interacted with the aortic valve. Hearts from six pigs were explanted and connected to an isolated working heart setup. A miniaturized LVAD was implanted within the left ventricle (tMVAD, HeartWare Inc., Miami Lakes, FL, USA). In four experiments blood was used to investigate hemodynamics under various loading conditions. In two experiments crystalloid perfusate was used, allowing visualization of the outflow cannula within the aortic valve. In all hearts the transapical miniaturized ventricular assist device (tMVAD) implantation was successful. In the blood experiments hemodynamics similar to those observed clinically were achieved. Pump speeds ranged from 9 to 22 krpm with a maximum of 7.6 L/min against a pressure difference between ventricle and aorta of ∼50 mm Hg. With crystalloid perfusate, central positioning of the outflow cannula in the aortic root was observed during full and partial support. With decreasing aortic pressures the cannula tended to drift toward the aortic root wall. The tMVAD could unload the ventricle similarly to LVADs under conventional cannulation. Aortic pressure influenced central positioning of the outflow cannula in the aortic root. The isolated heart is a simple, accessible evaluation platform unaffected by complex reactions within a whole, living animal. This platform allowed detection and visualization of potential hazards.

Evaluation of a ventricular assist device system: stability in a proton beam therapy.

Inadequate research exists regarding testing of a ventricular assist device (VAD) for susceptibility to radiation damage. Specifically, minimal data are available to radiation oncologists prescribing treatment plans for patients with an implanted VAD. As the number of implanted devices increases, patients requiring radiation at tissue sites near or at the device will increase. The purpose of this study is to provide the first analysis of radiation effects of proton beams on VADs. Five left VAD (LVAD) pumps (HeartWare Inc., Miami Lakes, FL) were exposed to proton beam radiation at a calibrated dose rate of 5 Gy/min up to a cumulative dose of 70 Gy. The Heartware LVAD pump recorded parameters including power (W), speed (revolutions/min), and estimated flow (L/min). Analysis of collected data after each irradiation found no deviation in pump parameters from baseline values. The Heartware LVAD pump exhibited no change in device function when directly irradiated by a high energy proton beam. Secondary neutron fluence created in the proton beam during irradiation had no effect on external components including the system controller and batteries powering the Heartware LVAD.

Evaluation of a ventricular assist device: stability under x-rays and therapeutic beam attenuation.

Improved outcomes and quality of life of heart failure patients have been reported with the use of left ventricular assist devices (LVADs). However, little information exists regarding devices in patients undergoing radiation cancer treatment. Two HeartWare Ventricular Assist Device (HVAD) pumps were repeatedly irradiated with high intensity 18 MV x-rays to a dosage range of 64-75 Gy at a rate of 6 Gy/min from a radiation oncology particle accelerator to determine operational stability. Pump parameter data was collected through a data acquisition system. Second, a computerized tomography (CT) scan was taken of the device, and a treatment planning computer estimated characteristics of dose scattering and attenuation. Results were then compared with actual radiation measurements. The devices exhibited no changes in pump operation during the procedure, though the titanium components of the HVAD markedly attenuate the therapy beam. Computer modeling indicated an 11.8% dose change in the absorbed dosage that was distinctly less than the 84% dose change measured with detectors. Simulated and measured scattering processes were negligible. Computer modeling underestimates pretreatment dose to patients when the device is in the field of radiation. Future x-ray radiation dosimetry and treatment planning in HVAD patients should be carefully managed by radiation oncology specialists.

Identification and characterization of a multidomain hyperthermophilic cellulase from an archaeal enrichment.

Despite extensive studies on microbial and enzymatic lignocellulose degradation, relatively few Archaea are known to deconstruct crystalline cellulose. Here we describe a consortium of three hyperthermophilic archaea enriched from a continental geothermal source by growth at 90 °C on crystalline cellulose, representing the first instance of Archaea able to deconstruct lignocellulose optimally above 90 °C. Following metagenomic studies on the consortium, a 90 kDa, multidomain cellulase, annotated as a member of the TIM barrel glycosyl hydrolase superfamily, was characterized. The multidomain architecture of this protein is uncommon for hyperthermophilic endoglucanases, and two of the four domains of the enzyme have no characterized homologues. The recombinant enzyme has optimal activity at 109 °C, a half-life of 5 h at 100 °C, and resists denaturation in strong detergents, high-salt concentrations, and ionic liquids. Cellulases active above 100 °C may assist in biofuel production from lignocellulosic feedstocks by hydrolysing cellulose under conditions typically employed in biomass pretreatment.

Platelet activation in heart failure patients supported by the HeartMate II ventricular assist device.

OBJECTIVE: Thromboembolic events have been observed in heart failure (HF) patients supported by long-term mechanical circulatory support (MCS) devices. It has been hypothesized that these adverse events may be the result of platelet activation associated with high rotational speeds common to axial flow pumps. In this study, markers of platelet activation were investigated in HF patients supported by a HeartMate II left ventricular assist device (LVAD). METHODS: The study group consisted of 34 HF patients supported by a HeartMate II axial flow LVAD implanted for destination therapy (DT). This patient population was 94% male (31 M, 3 F), supported by LVAD for 30 to 723 days (average 268 days), and with an anticoagulation regimen of Coumadin (0-8 mg daily dose) and aspirin (0-325 mg daily dose). Platelet adhesion markers (soluble P-selectin and solube CD40 ligand), platelet count (PC), hematocrit (Hct), and creatinine (Cr) were measured. RESULTS: The soluble P-selectin marker was within normal platelet activity limits for all end points. The soluble CD40 ligand marker indicated platelet inactivity for all end points. Despite high shear stresses associated with a high-speed axial flow pump, the HeartMate II had no discernable effect on platelet activation. Current clinical doses of aspirin also appear to have little effect on platelet activation. Platelet count, hematocrit, and creatinine were normal in these patients over duration of support. CONCLUSIONS: There were no discernable changes in platelet activation markers soluble P-selectin and soluble CD40 ligand in HF patients support by HeartMate II LVAD independently of length of support, anti-platelet, and anti-coagulation regimens.

Evaluation of new Forcefield technology: reducing platelet adhesion and cell coverage of pyrolytic carbon surfaces.

INTRODUCTION: Platelet adhesion and activation are a significant source of clinical complications. Preventing foreign surface-platelet interaction may improve biocompatibility of implantable medical devices. This study evaluated efficacy of novel technique for electrically modifying surface of conductive biomaterial and attaching blood components to prevent thrombogenesis. Specifically, this new surface modification technology, Forcefield (ATS Medical, Inc, Minneapolis, Minn), was designed to prevent platelet adhesion on pyrolytic carbon. A modulated low-voltage current is directly applied to pyrolytic carbon surfaces to stimulate adherence of a layer of charged proteins from circulating blood components that is resistive to platelet deposition. METHODS: Feasibility of Forcefield technology was tested in line with cardiopulmonary bypass circuit in patients undergoing standard cardiac surgery (n = 6). Forcefield treatment was applied to segment of pyrolytic carbon with 15 minutes (n = 3) and 30 minutes (n = 3) of electrically stimulated exposure time, and resulting segments were compared with untreated pyrolytic carbon segment. Platelet adhesion confluence was then quantified by scanning electron microscopy. RESULTS: Confluence of the Forcefield-treated pyrolytic carbon segments (3.3% ± 2.2%) was significantly reduced relative to untreated pyrolytic carbon control segments (81.7% ± 24%, P < .001). There were no discernible differences in cell confluence with Forcefield-treated segments as function of exposure time (15 or 30 minutes). CONCLUSIONS: Forcefield technology may enable modification of pyrolytic carbon surfaces to prevent platelet adhesion and thrombogenesis of implanted medical devices, including heart valves, stents, catheters, and ventricular assist devices, and may eliminate the need for anticoagulant and antiplatelet therapies.

Expression of genes in cyanobacteria: adaptation of endogenous plasmids as platforms for high-level gene expression in Synechococcus sp. PCC 7002.

Synechococcus sp. PCC 7002 is an ideal model cyanobacterium for functional genomics and biotechnological applications through metabolic engineering. A gene expression system that takes advantage of its multiple, endogenous plasmids has been constructed in this cyanobacterium. The method involves the integration of foreign DNA cassettes with selectable markers into neutral sites that can be located on any of the several endogenous plasmids of this organism. We have exploited the natural transformability and powerful homologous recombination capacity of this organism by using linear DNA fragments for transformation. This approach overcomes barriers that have made the introduction and expression of foreign genes problematic in the past. Foremost among these is the natural restriction endonuclease barrier that can cleave transforming circular plasmid DNAs before they can be replicated in the cell. We describe herein the general methodology for expressing foreign and homologous genes in Synechococcus sp. PCC 7002, a comparison of several commonly used promoters, and provide examples of how this approach has successfully been used in complementation analyses and overproduction of proteins with affinity tags.

Polyphasic characterization of a thermotolerant siderophilic filamentous cyanobacterium that produces intracellular iron deposits.

Despite the high potential for oxidative stress stimulated by reduced iron, contemporary iron-depositing hot springs with circum-neutral pH are intensively populated with cyanobacteria. Therefore, studies of the physiology, diversity, and phylogeny of cyanobacteria inhabiting iron-depositing hot springs may provide insights into the contribution of cyanobacteria to iron redox cycling in these environments and new mechanisms of oxidative stress mitigation. In this study the morphology, ultrastructure, physiology, and phylogeny of a novel cyanobacterial taxon, JSC-1, isolated from an iron-depositing hot spring, were determined. The JSC-1 strain has been deposited in ATCC under the name Marsacia ferruginose, accession number BAA-2121. Strain JSC-1 represents a new operational taxonomical unit (OTU) within Leptolyngbya sensu lato. Strain JSC-1 exhibited an unusually high ratio between photosystem (PS) I and PS II, was capable of complementary chromatic adaptation, and is apparently capable of nitrogen fixation. Furthermore, it synthesized a unique set of carotenoids, but only chlorophyll a. Strain JSC-1 not only required high levels of Fe for growth (≥40 µM), but it also accumulated large amounts of extracellular iron in the form of ferrihydrite and intracellular iron in the form of ferric phosphates. Collectively, these observations provide insights into the physiological strategies that might have allowed cyanobacteria to develop and proliferate in Fe-rich, circum-neutral environments.

Roles of xanthophyll carotenoids in protection against photoinhibition and oxidative stress in the cyanobacterium Synechococcus sp. strain PCC 7002.

Synechococcus sp. strain PCC 7002 is a robust, genetically tractable cyanobacterium that produces six different xanthophyll carotenoids (zeaxanthin, cryptoxanthin, myxoxanthophyll (myxol-2'-fucoside), echinenone, 3'-hydroxyechinenone, and synechoxanthin) and tolerates many environmental stresses, including high light intensities. Targeted mutations were introduced to block the branches of the carotenoid biosynthetic pathway leading to specific xanthophylls, and a mutant lacking all xanthophylls was constructed. Some of the mutants showed severe growth defects at high light intensities, and multi-locus mutants had somewhat lower chlorophyll contents and lower photosystem I levels. The results suggested that xanthophylls, particularly zeaxanthin and echinenone, might play regulatory roles in thylakoid biogenesis. Measurements of reactive oxygen (ROS) and nitrogen (RNS) species in the mutants showed that all xanthophylls participate in preventing ROS/RNS accumulation and that a mutant lacking all xanthophylls accumulated very high levels of ROS/RNS. Results from transcription profiling showed that mRNA levels for most genes encoding the enzymes of carotenogenesis are significantly more abundant after exposure to high light. These studies indicated that all xanthophylls contribute to protection against photo-oxidative stress.

HeartWare miniature axial-flow ventricular assist device: design and initial feasibility test.

Pulsatile ventricular assist devices have successfully provided circulatory support for many patients throughout the past quarter century; however, persistent complications have hindered expanded clinical application of this technology. Although the use of smaller, continuous-flow ventricular assist device pumps has reduced the frequency and severity of some adverse events, design enhancement may further improve outcomes for patients who require long-term left ventricular support. One new product, the HeartWare, Inc., miniature ventricular assist device, features a wide-bladed rotor design in an axial-flow pump with a strong, passively suspended magnetic rotor. The operating range of 16,000 to 28,000 rpm can provide up to 10 L/min of flow. The wide blades portend minimal cellular trauma.This new device has not yet been approved for use in human beings. As a test, we implanted it in a calf, and we continuously monitored the device's performance and the hemodynamic results over 30 days. No mechanical failure occurred, and no thrombi were noted upon explantation of the device. The animal's circulation was stable during the test period, and no end-organ abnormalities were found upon autopsy. The potential benefits of this miniature ventricular assist device are its increased availability to a broader patient population, a lower risk of infection, simplified implantation procedures, and improved durability. Further in vivo testing is planned. Herein, we discuss the unique design of the HeartWare miniature ventricular assist device, our feasibility study of its performance, and the possibilities for its use in human beings.

The biosynthetic pathway for myxol-2' fucoside (myxoxanthophyll) in the cyanobacterium Synechococcus sp. strain PCC 7002.

Synechococcus sp. strain PCC 7002 produces a variety of carotenoids, which comprise predominantly dicylic beta-carotene and two dicyclic xanthophylls, zeaxanthin and synechoxanthin. However, this cyanobacterium also produces a monocyclic myxoxanthophyll, which was identified as myxol-2' fucoside. Compared to the carotenoid glycosides produced by diverse microorganisms, cyanobacterial myxoxanthophyll and closely related compounds are unusual because they are glycosylated on the 2'-OH rather than on the 1'-OH position of the psi end of the molecule. In this study, the genes encoding two enzymes that modify the psi end of myxoxanthophyll in Synechococcus sp. strain PCC 7002 were identified. Mutational and biochemical studies showed that open reading frame SynPCC7002_A2032, renamed cruF, encodes a 1',2'-hydroxylase [corrected] and that open reading frame SynPCC7002_A2031, renamed cruG, encodes a 2'-O-glycosyltransferase. The enzymatic activity of CruF was verified by chemical characterization of the carotenoid products synthesized when cruF was expressed in a lycopene-producing strain of Escherichia coli. Database searches showed that homologs of cruF and cruG occur in the genomes of all sequenced cyanobacterial strains that are known to produce myxol or the acylic xanthophyll oscillaxanthin. The genomes of many other bacteria that produce hydroxylated carotenoids but do not contain crtC homologs also contain cruF orthologs. Based upon observable intermediates, a complete biosynthetic pathway for myxoxanthophyll is proposed. This study expands the suite of enzymes available for metabolic engineering of carotenoid biosynthetic pathways for biotechnological applications.

Complete genome sequence of the aerobic CO-oxidizing thermophile Thermomicrobium roseum.

In order to enrich the phylogenetic diversity represented in the available sequenced bacterial genomes and as part of an "Assembling the Tree of Life" project, we determined the genome sequence of Thermomicrobium roseum DSM 5159. T. roseum DSM 5159 is a red-pigmented, rod-shaped, Gram-negative extreme thermophile isolated from a hot spring that possesses both an atypical cell wall composition and an unusual cell membrane that is composed entirely of long-chain 1,2-diols. Its genome is composed of two circular DNA elements, one of 2,006,217 bp (referred to as the chromosome) and one of 919,596 bp (referred to as the megaplasmid). Strikingly, though few standard housekeeping genes are found on the megaplasmid, it does encode a complete system for chemotaxis including both chemosensory components and an entire flagellar apparatus. This is the first known example of a complete flagellar system being encoded on a plasmid and suggests a straightforward means for lateral transfer of flagellum-based motility. Phylogenomic analyses support the recent rRNA-based analyses that led to T. roseum being removed from the phylum Thermomicrobia and assigned to the phylum Chloroflexi. Because T. roseum is a deep-branching member of this phylum, analysis of its genome provides insights into the evolution of the Chloroflexi. In addition, even though this species is not photosynthetic, analysis of the genome provides some insight into the origins of photosynthesis in the Chloroflexi. Metabolic pathway reconstructions and experimental studies revealed new aspects of the biology of this species. For example, we present evidence that T. roseum oxidizes CO aerobically, making it the first thermophile known to do so. In addition, we propose that glycosylation of its carotenoids plays a crucial role in the adaptation of the cell membrane to this bacterium's thermophilic lifestyle. Analyses of published metagenomic sequences from two hot springs similar to the one from which this strain was isolated, show that close relatives of T. roseum DSM 5159 are present but have some key differences from the strain sequenced.

The Biosynthetic pathway for synechoxanthin, an aromatic carotenoid synthesized by the euryhaline, unicellular cyanobacterium Synechococcus sp. strain PCC 7002.

The euryhaline, unicellular cyanobacterium Synechococcus sp. strain PCC 7002 produces the dicyclic aromatic carotenoid synechoxanthin (chi,chi-caroten-18,18'-dioic acid) as a major pigment (>15% of total carotenoid) and when grown to stationary phase also accumulates small amounts of renierapurpurin (chi,chi-carotene) (J. E. Graham, J. T. J. Lecomte, and D. A. Bryant, J. Nat. Prod. 71:1647-1650, 2008). Two genes that were predicted to encode enzymes involved in the biosynthesis of synechoxanthin were identified by comparative genomics, and these genes were insertionally inactivated in Synechococcus sp. strain PCC 7002 to verify their function. The cruE gene (SYNPCC7002_A1248) encodes beta-carotene desaturase/methyltransferase, which converts beta-carotene to renierapurpurin. The cruH gene (SYNPCC7002_A2246) encodes an enzyme that is minimally responsible for the hydroxylation/oxidation of the C-18 and C-18' methyl groups of renierapurpurin. Based on observed and biochemically characterized intermediates, a complete pathway for synechoxanthin biosynthesis is proposed.

Synechoxanthin, an aromatic C40 xanthophyll that is a major carotenoid in the cyanobacterium Synechococcus sp. PCC 7002.

A major aromatic, dicarboxylate carotenoid (>15% of total) was isolated from the euryhaline cyanobacterium Synechococcus sp. PCC 7002. This compound, which was given the common name synechoxanthin (1), has been assigned the structure (all-E) chi,chi-caroten-18,18'-dioic acid by a combination of spectroscopic (UV-vis, FT-IR, (1)H and (13)C NMR, LC-MS) and chemical methods. This discovery conclusively establishes that some cyanobacteria are capable of synthesizing aromatic carotenoids.

Improvement in early oxygen uptake kinetics with left ventricular assist device support.

Sustained myocardial recovery and reversal of heart failure has been reported with the use of left ventricular assist devices (LVADs). However, clinical predictors of sustained recovery have not been clearly defined, and little information exists regarding exercise improvement in LVAD patients. Therefore, we sought to determine whether peripheral oxygen delivery and utilization were improved with LVAD support. Eleven patients with available pre- and post-LVAD cardiopulmonary exercise (CPX) data were studied retrospectively. Five patients received a HeartMate XVE for destination therapy (DT) and six patients received a Thoratec PVAD pneumatic LVAD for bridge-to-recovery (BTR). Oxygen uptake kinetics was assessed by fitting a single exponential function to the VO2 response. There was a significant improvement in several key parameters of cardiac performance including peak VO2, VO2 at anaerobic threshold (AT), oxygen kinetics as measured by mean response time (MRT), and oxygen deficit during LVAD support. Oxygen deficiency improved from 0.29 +/- 0.16 ml/kg to 0.16 +/- 0.06 ml/kg (p = 0.023), as did MRT 68 +/- 47.7 seconds to 35.8 +/- 13.3 seconds (p = 0.046) with LVAD support. Improved oxygen kinetics suggests improved peripheral utilization of oxygen, and may offer an additional clinical parameter to predict the likelihood of sustained recovery.

The biochemical basis for structural diversity in the carotenoids of chlorophototrophic bacteria.

Ongoing work has led to the identification of most of the biochemical steps in carotenoid biosynthesis in chlorophototrophic bacteria. In carotenogenesis, a relatively small number of modifications leads to a great diversity of carotenoid structures. This review examines the individual steps in the pathway, discusses how each contributes to structural diversity among carotenoids, and summarizes recent progress in elucidating the biosynthetic pathways for carotenoids in chlorophototrophs.

Destination therapy: safety and feasibility of national and international travel.

Results for Destination Therapy (DT) continue to improve with advanced technology, better patient selection, and experienced clinical management. Quality of life for these patients is an important component of the overall success of DT, and traveling is becoming more common. We reviewed our experience with long-distance travel in our DT population. All patients implanted with a left ventricular assist device for DT were followed prospectively. Long-distance travel was considered to be >200 miles, one way from their homes. There were 15 patients (14 men) with an average age of 66 years (range, 30-82) who traveled a combined total of 40 long-distance trips. Four trips were international (Spain, Canada (2), and Puerto Rico), 35 within the continental U.S., and one to Hawaii. The average one way distance traveled was 925 miles with a range of 218-4256 miles. The average time away from home was 8.3 days (range, 2-30). Patients traveled by airplane (17), car (23), and one trip included a 5 day cruise. Five complications occurred: driveline trauma, delay of reentry into the United States, missed flight, red heart alarm from bearing wear, and dehydration. All patients returned home safely for routine follow-up. Long-distance travel is possible for DT patients. Anticipating potential problems and careful planning is necessary for safe national and international travel.

Reducing the effects of the systemic inflammatory response to cardiopulmonary bypass: can single dose steroids blunt systemic inflammatory response syndrome?

The use of cardiopulmonary bypass (CPB) is associated with the development of a significant systemic inflammatory response syndrome (SIRS) which can affect patient outcomes. Multiple pathways are involved in initiating and maintaining SIRS. We studied whether a single dose of steroids (dexamethasone) after the induction of anesthesia could blunt the SIRS from CPB. A prospective, randomized, double-blinded, placebo control trial of 28 patients (13 study vs. 15 control). The study group received 100 mg of dexamethasone whereas the control group received sterile saline. Inclusion criteria were the following: elective coronary artery bypass grafting, less than 80 years old, normal ejection fraction, no acute myocardial infarction. Serum levels of C3a, interleukin (IL)-6, and plasma norepinephrine (PNE) were measured after intubation, 30 minutes after initiation of CPB, 24 and 72 hours after termination of bypass. The study group demonstrated significantly lower levels of IL-6 (p = 0.0005) at 24 hours and PNE (p = 0.05) at 72 hours post-CPB. There were no differences in the C3a levels between the groups. No infections occurred in either group. A single dose of dexamethasone reduces IL-6 and PNE levels associated with CPB. Despite the significant reductions in IL-6 and PNE, there was no effect on clinical outcomes. Additional studies are needed to demonstrate a clinically significant effect on patient outcomes.

Fibrinolytic activation during long-term support with the HeartMate II left ventricular assist device.

Human physiologic responses to pulsatile left ventricular assist devices (LVADs) are well understood; responses to the newer continuous flow pumps are not. Therefore, we evaluated the long-term effects of continuous flow LVAD support on fibrinolytic activation. Twelve recipients of an axial flow LVAD as destination therapy were assessed for fibrinolytic activation at 1, 3, 6, 9, and 12 months postimplantation. The fibrinolytic response and changes were assessed in terms of fibrinogen, D-dimer, plasma free hemoglobin, international normalized ratio (INR), and red blood cell (RBC) sedimentation rate. Bleeding and thromboembolic events were recorded. All fibrinolytic response parameters were elevated at baseline; mean RBC sedimentation rate was 51.8 mm/h, mean D-dimer was 3.95 nmol/L, and the mean fibrinogen was 356 mg/dl. The D-dimer and fibrinogen levels increased after LVAD implantation but returned to near-normal levels by 12 months. Red blood cell sedimentation rates increased indicating ongoing inflammation. Plasma free hemoglobin values decreased and remained low, an indicator of low shear rates and hemolysis. Three nonfatal bleeding events but no thromboembolic events were observed. Fibrinolytic responses initially increase after LVAD implantation but then gradually normalize.