Nonpulsatile Left Ventricular Assist Devices Research Articles

Right Ventricular Longitudinal Strain In Left Ventricular Assist Device Surgery–A Retrospective Cohort Study

Right ventricular (RV) failure is common after left ventricular assist device (LVAD) surgery and is associated with higher mortality. Measurement of longitudinal RV strain using speckle-tracking technology is a novel approach to quantify RV function. The authors hypothesized that depressed peak longitudinal RV strain measured by intraoperative transesophageal echocardiography (TEE) examinations would be associated with adverse outcomes after LVAD surgery. Retrospective cohort study. Tertiary academic medical center. Following Institutional Review Board approval, the authors retrospectively identified adult patients who underwent implantation of non-pulsatile LVAD. Exclusion criteria included inadequate TEE images and device explantation within 6 months for heart transplantation. None. The postoperative adverse event outcome was defined as a composite of one or more of death within 6 months, ≥14 days of inotropes, mechanical RV support, or device thrombosis. Intraoperative TEE images were analyzed for peak RV free wall longitudinal strain by two blinded investigators. Simple logistic regression was used to assess the relationship between adverse outcome and the mean of the strain measurements of the two raters. Agreement between the raters was assessed by intra-class correlation (0.62) and Pearson correlation coefficient (0.63). Of the 57 subjects, 21 (37%) had an adverse outcome. The logistic regression indicated no significant association between RV peak longitudinal strain and adverse events. In this retrospective study of patients undergoing non-pulsatile LVAD implantation, peak longitudinal strain of the RV free wall was not associated with adverse outcomes within 6 months after surgery. Additional quantitative echocardiographic measures for intraoperative RV assessment should be explored.

Invited Commentary

Left ventricular assist devices (LVADs) continue to be an important therapy for patients with end-stage heart failure. While survival with a LVAD is superior to medical therapy alone, device-related complications are unfortunately common. Nonsurgical bleeding is a particularly serious challenge, as it negatively affects a large percentage of patients receiving LVAD therapy. This phenomenon is thought, in part, to result from the mechanical interface of the device with patient blood. Supraphysiologic shear stress is notable in the newer generation of nonpulsatile LVADs and can induce degradation of important clotting factors, including von Willebrand Factor (vWF). In this article, the authors [1Bartoli C.R. Kang J. Zhang D. et al.Left ventricular assist device design reduces von Willebrand factor degradation: a comparative study between the HeartMate II and the EVAHEART left ventricular assist system.Ann Thorac Surg. 2017; 103: 1239-1245Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar] use a mock circulatory loop to compare two devices: the axial flow HeartMate II and the centrifugal pump EVAHEART LVAS. Whole blood was run through each of the mock loops, and levels of vWF and its degradation products were measured at 6-hour intervals. This study found a significant increase in the breakdown of vWF with the axial flow device compared with the centrifugal pump. While they acknowledge that other design features might affect their results, the authors attribute less breakdown of vWF with the centrifugal pump to the relatively larger blood gaps and lower revolutions per minute associated with the device. This study is an important demonstration of how pump mechanics can dramatically affect the components of circulating blood. The bench model does not account for endothelial function or other physiologic parameters found in vivo. However, the purity of design enables researchers to examine directly how a change in pump properties can help to minimize blood trauma. Ultimately, more patients are now living longer with mechanical circulatory support. To minimize device-related complications, such as nonsurgical bleeding, it is important to understand the effects of design features. Studies such as these will help to inform the next generation of devices. Left Ventricular Assist Device Design Reduces von Willebrand Factor Degradation: A Comparative Study Between the HeartMate II and the EVAHEART Left Ventricular Assist SystemThe Annals of Thoracic SurgeryVol. 103Issue 4PreviewSupraphysiologic shear stress from continuous-flow left ventricular assist devices (LVADs) accelerates von Willebrand factor (vWF) degradation and predisposes patients to nonsurgical bleeding. It is unknown whether unique design characteristics of LVADs differentially affect vWF degradation. We tested the hypothesis that the centrifugal-flow EVAHEART (Evaheart, Houston, TX) left ventricular assist system (LVAS), which was designed to minimize shear stress (low operational revolutions per minute [rpm], larger flow gaps, low shear stress, flat H-Q curve), reduced vWF degradation versus the axial-flow HeartMate II (Thoratec, Pleasanton, CA) LVAD. Full-Text PDF

Tu1362 Temporal Relationship and Predictors of Gastrointestinal Bleeding in Recipients of Non-Pulsatile Left Ventricular Assist Devices

Tu1362 Temporal Relationship and Predictors of Gastrointestinal Bleeding in Recipients of Non-Pulsatile Left Ventricular Assist Devices

(131) - Increased Aortic Stiffness Index Among Patients Bridged to Transplant with Non-Pulsatile Left Ventricular Assist Devices

(131) - Increased Aortic Stiffness Index Among Patients Bridged to Transplant with Non-Pulsatile Left Ventricular Assist Devices

Intensivecare treatment of patients with left ventricular assist devices

Apart from heart transplantation, implantation of a left ventricular assist device (LVAD) is the only established surgical treatment for therapy-refractory terminal left heart failure, The specific intensive care unit (ICU) management of these patients depends on the reason for the ICU admission and requires understanding of the characteristic hemodynamics of non-pulsatile LVADs as well as of the inherent problems. Knowledge about the specific features in hemodynamic monitoring, understanding of pump characteristics, management of anticoagulation and hemostasis and the handling of problems, such as right heart failure, aortic valve insufficiency and infections is essential. The management of unconscious LVAD patients can be challenging. It requires a sophisticated transthoracic and transesophageal echocardiography (TTE/TEE) examination, targeted laboratory diagnostics and consideration of possible alternative diagnoses. Professional interdisciplinary cooperation and exchange of current knowledge is crucial.

Impact of Implantable Cardioverter Defibrillators on Survival of Patients with Centrifugal Left Ventricular Assist Devices.

Both implantable cardioverter defibrillators (ICDs) and left ventricular assist devices (LVADs) have a positive impact on survival in the heart failure population. We sought to determine whether these positive effects on survival are additive or whether LVAD therapy supersedes ICD therapy. We analyzed survival data of patients implanted with nonpulsatile LVADs between October 2004 and March 2013. Survival in patients with ICDs (n = 64) was compared to those without ICDs (n = 36). Patients exited the study at the time of heart transplantation or death. A total of 100 patients underwent LVAD implantation during this time. Patients had a mean follow-up time of 364 ± 295 days. Death occurred in 15 (38%) patients in the no ICD group versus 18 (30%) in the ICD group. Univariate analysis demonstrated a marginal early survival benefit at up to 1 year post-LVAD implant in the ICD cohort; however, at time points greater than 1 year there was no statistically significant benefit in ICD therapy in LVAD patients (P = 0.56). Multivariate analysis did not show any significant predictor of survival. There were no patients who died of sudden cardiac death. There was no significant difference in the time to heart transplantation (443 days ± 251 no ICD vs 372 days ± 277 ICD, P = 0.37). The benefit of ICD therapy in the setting of continuous flow LVAD therapy is uncertain. Although prolonged ventricular arrhythmias (VAs) may potentially impact on patient survival, LVAD therapy is beneficial in prevention of sudden cardiac death due to VAs.

Abstract 15253: A Paradoxical Rise in Serum Copeptin After Non-Pulsatile LVAD: a New SIADH?

Introduction: Hyponatremia (Na< 136 mmol/L) is prevalent (~28%) among hospitalized heart failure (HF) patients and a marker of advanced/end-stage HF(AHF) with increased mortality. Treatment of hyponatremia has no survival benefit in this population. In a prospective study of AHF patients, we sought to define the prevalence, pathophysiology and role of V2 vasoreceptor activity in the development of hyponatremia. Serum copeptin (S-COP), a surrogate marker for AVP activity, was assessed during AHF therapies (AHFT) which included axial-non-pulsatile left ventricular assist device (LVAD) and/or heart transplant (HTx). Methods: Serum samples were collected from AHF patients pre and post AHFT and compared with normal controls. S-COP levels were assessed using an enzyme linked immunosorbant assay and correlated to clinical variables, serum Sodium (S-Na) and glomerular filtration rate (eGFR). Results: Among 89 consecutive (mean age 56.2±15.35; M=69) patients awaiting AHFT, 54 (60%) were hyponatremic. Preop S-COP was elevated compared to controls (0.68±0.50 vs 0.53±0.13 ng/ml, P=.02) and inversely correlated to S-Na and eGFR (r=-0.23, P<.05, r=-0.23, P<.05; N=81); conversely, eGFR and S-Na were uncorrelated. AHFT (n=42) normalized S-Na (133.2±4.1 vs 136.1±3.5 mmol/l; P=.001) and improved eGFR (47.7±13.6 vs 52.7±9.7 mL/min/1.73sqm; P=.001); however, post LVAD (n=34) S-COP rose (0.67±0.21 vs 1.84±0.76 ng/ml; P<.0001) with incomplete normalization of S-NA (132.9±4.3 vs 135.9±3.8 mmol/l; P<.01). In contrast, post HTx (n=9) S-COP was unchanged to pre-AHFT (0.59±0.32 vs 0.65±0.16 ng/ml; P>.1) and was lower compared to post LVAD (0.65±0.16 vs 1.84±0.76 ng/ml; P<.0001). Elevated S-COP with LVAD as bridge to transplant (n=3) showed a marked decrease post HTx (2.7±0.50 vs 1.0±0.29 ng/ml; P<.01). Conclusions: In AHF, the prevalence of hyponatremia is double compared to acute hospitalized HF and associated with S-COP surge prior to AHFT. Unexpectedly, LVAD but not HTx was associated with rising S-COP and incomplete S-Na recovery despite clinical improvement, suggesting inappropriate antidiuretic hormone release. The association of S-COP rise with non-pulsatile LVAD and potential benefit of long-term AVP inhibition post LVAD merits further studies.

Neurohormonal regulation and improvement in blood glucose control: reduction of insulin requirement in patients with a nonpulsatile ventricular assist device.

Heart failure is associated with prolonged stress and inflammation characterized by elevated levels of cortisol and circulating catecholamines. Persistent sympathetic stimulation secondary to the stress of heart failure causes an induced insulin resistance, which creates a need for higher doses of insulin to adequately manage hyperglycemia in this patient population. We hypothesized that cortisol and catecholamine levels would be elevated in end-stage heart failure patients, however, would be reduced after the implantation of a left ventricular assist device (LVAD). Insulin requirements would therefore be reduced post LVAD implant and control of diabetes improved as compared with pre-implant. Pre- and postoperative cortisol, catecholamine, glycated hemoglobin, and blood glucose levels were evaluated retrospectively in 99 LVAD patients at a single center from January 2007 through November 2011. Serum was collected before LVAD implantation and monthly after implantation for 12 months consecutively. Results were evaluated and compared to insulin requirements, if any, before and after implant. Plasma levels were measured by ELISA. There were a total of 99 patients (81 men and 18 women). Two patients were implanted twice due to pump dysfunction. Mean age was 59 years, ± 10, with a median of 63 years. Of those patients, 64 had ischemic cardiomyopathy and 35 had dilated cardiomyopathy. The total patient years of LVAD support were 92.5 years. All patients received a continuous flow left ventricular assist device. Type II diabetes mellitus was diagnosed in 28 patients. Of those patients, 24 required daily insulin with an average dose of 45 units/day. Average preoperative glycated hemoglobin (HbA1c) levels were 6.8% with fasting blood glucose measurements of 136 mg/dL. Mean cortisol levels were measured at 24.3 μg/dL before LVAD implantation, with mean plasma catecholamine levels of 1824 μg/mL. Post operatively, average HbA1c levels were 5.38% with fasting blood glucose measurements of 122 mg/dL. Mean cortisol levels were measured at 10.9 μg/dL with average plasma catecholamine levels were 815 μg/mL. There was a significant decrease in both cortisol levels post LVAD implant (P = 0.012) as well as catecholamine levels (P = 0.044). The average insulin requirements post LVAD implant were significantly reduced to 13 units/day (P = 0.001). Six patients no longer required any insulin after implant. Implantation of nonpulsatile LVADs has become a viable option for the treatment of end-stage heart failure, helping to improve patient quality of life by decreasing clinical symptoms associated with poor end-organ perfusion. Frequently, diabetes is a comorbid condition that exists among heart failure patients and with the reduction of the systemic inflammatory and stress response produced by the support of a nonpulsatile LVAD, many patients may benefit from a reduction in their blood glucose levels, as well as insulin requirements.

The Use of Prothrombin Complex Concentrates in Two Patients With Non-Pulsatile Left Ventricular Assist Devices

LEFT VENTRICULAR ASSIST DEVICES (LVADs) are becoming more prevalent in the treatment of heart failure. Nonpulsatile LVADs require long-term anticoagulation to prevent device thrombosis. Life-threatening bleeding or the need for urgent noncardiac surgery may necessitate reversal of this anticoagulation. The authors describe 2 cases of successful reversal of oral anticoagulation with prothrombin complex concentrates (PCCs) in patients with LVADs undergoing urgent noncardiac surgery, without evidence of device thrombosis.

LVAD-Associated Coagulopathy: Contribution of Phosphatidylserine (PS+) Cellular Microparticles to the Risk of Hemorrhage and Thrombosis in Patients with Non-Pulsatile Left Ventricular Assist Devices

Purpose Left ventricular assist devices (LVADs) are associated with significant hemorrhagic and thrombotic complications, but the underlying mechanisms remain elusive. We examined whether cellular derived microparticles may be associated to adverse events in patients with LVADs. Methods and Materials We prospectively enrolled 15 patients undergoing elective implantation of a HeartMate II LVAD. Extensive coagulation profile including phosphatidylserine (PS+) cellular microparticles derived by platelets, leukocytes, erythrocytes, and endothelial cells was performed by flow cytometry. Samples were obtained upon admission (baseline), at discharge,at 3 months after discharge, and at the time of a clinically significant event. Patients were on an oral anticoagulation regimen of aspirin, warfarin (International Normalized Ratio, 2-3), and dipyridamole. Results Three patients had adverse events.At baseline, the mean percentage of PS+ microparticles in patients was higher than that in healthy controls (2.32%±1.65 vs. 0.98%±0.66) and gradually decreased during follow-up from 2.03%±1.35 (discharge) to 1.85%±1.22 (3 months). Patients with events had significantly more PS+ microparticles than did patients without events at 3 months (3.8%±0.75 vs. 1.85%±1.22, p Conclusions PS+ microparticles were elevated in patients before LVAD implantation, which is consistent with a hypercoagulable state. Anticoagulation after LVAD implantation appeared to reduce the amount of circulating PS+ microparticles in peripheral blood. Adverse thrombotic or bleeding events appeared to be preceded by elevated PS+ microparticles. The presence of these cell-derived particles may provide a procoagulant substrate that leads to significant adverse events.

Left Ventricular Assist Devices and Gastrointestinal Bleeding: A Narrative Review of Case Reports and Case Series

The use of left ventricular assist devices (LVADs) has become a state-of-the-art therapy for advanced cardiac heart failure; however, multiple reports in the literature describe an increased risk for gastrointestinal (GI) bleeding in these patients. We characterized this association by reviewing recent studies on this topic. GI bleeding occurs frequently in patients with LVADs, especially with devices with nonpulsatile flow patterns. We performed a comprehensive literature review to identify articles that reported GI bleeding in patients with LVADs. Databases used included PubMed, EMBASE, Scopus, Web of Knowledge, and Ovid. Baseline and outcome data were then ed from these reports. We identified 10 case reports and 22 case series with 1543 patients. The mean age was 54.2 years. Most patients had nonpulsatile LVADs (1316, 85.3%). Three hundred and seventeen patients (20.5%) developed GI bleeding; this occurred more frequently in patients with nonpulsatile LVADs. Multiple procedures were performed without complications but often did not identify a definite bleeding site. Suspect lesions occurred throughout the GI tract but were more frequent in the upper GI tract. Many patients had arteriovenous malformations. All patients received medical therapy. None of the patients had their LVAD replaced. The use of anticoagulation did not appear to predispose these patients to more GI bleeding episodes. Patients with LVADs have frequent GI bleeds, especially from arteriovenous malformations, which can occur throughout the GI tract. Most diagnostic and therapeutic interventions can be used safely in these patients. The pathogenesis of the GI bleeding in these patients may involve the use of anticoagulant medications, the formation of arteriovenous malformations, loss of von Willebrand factor activity, and mucosal ischemia.

Impact of Implantable Cardioverter Defibrillators on Survival of Patients with Centrifugal Left Ventricular Assist Devices

Background: Both Implantable Cardioverter Defibrillators (ICD) and Left Ventricular Assist Devices (LVAD) have a positive impact on survival in the heart failure population. We sought to determine whether these effects on survival are additive or whether LVAD therapy supersedes ICD therapy. Method: We analysed survival data of patients implanted with non-pulsatile, centrifugal LVADs between October 2004 and March 2013. Outcomes in patients with ICDs (n = 61) were compared to those without ICDs (n = 39). Patients exited the study at the time of heart transplantation or death. Results: 100 patients underwent LVAD implantation during the specified dates (92 Bridge-to-transplant, eight Destination-therapy). Mean follow up time was 364 ± 295 days. Death occurred in 15 (38%) patients in the No ICD group vs. 18 (30%) in the ICD group (p = 0.55). At day 500 post LVAD implant, there was no significant difference in Kaplan–Meier survival curves between the two groups (p = 0.21). The two most common causes of death were sepsis, which occurred in nine (27%) patients, and intracranial haemorrhage in seven (21%). There were no patients that died of sudden cardiac death. One patient died whilst in sustained (1 h) ventricular fibrillation in the context of progressive multi-organ failure and sepsis. There was no significant difference in the time to heart transplantation (443 ± 251 days no ICD vs. 372 ± 277 days ICD, p = 0.37). Conclusion: Whilst ICD therapy has an established role in heart failure, there is no long term benefit from ICD therapy in the setting of non-pulsatile LVAD therapy for end-stage heart failure.

Sympathetic Neural and Hemodynamic Responses to Upright Tilt in Patients With Pulsatile and Nonpulsatile Left Ventricular Assist Devices

Left ventricular assist devices (LVADs) are now widely accepted as an option for patients with advanced heart failure. First-generation devices were pulsatile, but they had poor longevity and durability. Newer generation devices are nonpulsatile and more durable, but remain associated with an increased risk of stroke and hypertension. Moreover, little is understood about the physiological effects of the chronic absence of pulsatile flow in humans. We evaluated patients with pulsatile (n=6) and nonpulsatile (n=11) LVADs and healthy controls (n=9) during head-up tilt while measuring hemodynamics and muscle sympathetic nerve activity. Patients with nonpulsatile devices had markedly elevated supine and upright muscle sympathetic nerve activity (mean±SD, 43±15 supine and 60±21 bursts/min at 60° head-up tilt) compared with patients with pulsatile devices (24±7 and 35±8 bursts/min; P<0.01) and controls (11±6 and 31±6 bursts/min; P<0.01); however, muscle sympathetic nerve activity was not different between patients with pulsatile flow and controls (P=0.34). Heart rate, mean arterial pressure, and total peripheral resistance were greater, whereas cardiac output was smaller, in LVAD patients compared with controls in both supine and upright postures. However, these hemodynamic variables were not significantly different between patients with pulsatile and nonpulsatile flow. Heart failure patients with continuous, nonpulsatile LVADs have marked sympathetic activation, which is likely due, at least in part, to baroreceptor unloading. We speculate that such chronic sympathetic activation may contribute to, or worsen end-organ diseases, and reduce the possibility of ventricular recovery. Strategies to provide some degree of arterial pulsatility, even in continuous flow LVADs may be necessary to achieve optimal outcomes in these patients.

Continuous flow left ventricular assist devices: a valid option for heart failure patients

Recent outstanding clinical advances with new mechanical circulatory systems (MCS) have led to additional strategies in the treatment of end stage heart failure (HF). Heart transplantation (HTx) can be postponed and for certain patients even replaced by smaller implantable left ventricular assist devices (LVAD). Mechanical support of the failing left ventricle enables appropriate hemodynamic stabilisation and recovery of secondary organ failure, often seen in these severely ill patients. These new devices may be of great help to bridge patients until a suitable cardiac allograft is available but are also discussed as definitive treatment for patients who do not qualify for transplantation. Main indications for LVAD implantation are bridge to recovery, bridge to transplantation or destination therapy. LVAD may be an important tool for patients with an expected prolonged period on the waiting list, for instance those with blood group 0 or B, with a body weight over 90 kg and those with potentially reversible secondary organ failure and pulmonary artery hypertension. However, LVAD implantation means an additional heart operation with inherent peri-operative risks and complications during the waiting period. Finally, cardiac transplantation in patients with prior implantation of a LVAD represents a surgical challenge. This review summarises the current knowledge about LVAD and continuous flow devices especially since the latter have been increasingly used worldwide in the most recent years. The review is also based on the institutional experience at Berne University Hospital between 2000 and 2012. Apart from short-term devices (Impella, Cardiac Assist, Deltastream and ECMO) which were used in approximately 150 cases, 85 pulsatile long-term LVAD, RVAD or bi-VAD and 44 non-pulsatile LVAD (mainly HeartMateII and HeartWare) were implanted. After an initial learning curve, one-year mortality dropped to 10.4% in the last 58 patients.

Laparoscopic Gastric Bypass in a Patient With an Implanted Left Ventricular Assist Device

CONGESTIVE HEART FAILURE (CHF) is a growing health issue, with significant morbidity and mortality. Of the 5.8 million Americans affected by CHF, approximately one third of these suffer from nonischemic cardiomyopathy. 1 American Heart AssociationHeart Disease and Stroke Statistics—2010 Update. American Heart Association, Dallas, TX2010 Google Scholar Left ventricular assist devices (LVADs) provide mechanical support to the heart and potentially can reverse the progression of heart failure. 2 Thoratec CorporationLearning About The HeartMate II LVAD. www.thoratec.com/downloads/LVAD-FactSheet.pdf Google Scholar , 3 Morgan J.A. John R. Rao V. et al. Bridging to transplant with the HeartMate left ventricular assist device: The Columbia Presbyterian 12-year experience. J Thorac Cardiovasc Surg. 2004; 127: 1309-1316 Abstract Full Text Full Text PDF PubMed Scopus (96) Google Scholar LVAD therapy improves heart failure symptoms by 1 to 2 New York Heart Association classes, improves hepatic and renal function, and can improve patient functional capacity. More than 5,000 patients have received a Heartmate II (Thoratec Corp, Pleasanton, CA) LVAD since 2005. 2 Thoratec CorporationLearning About The HeartMate II LVAD. www.thoratec.com/downloads/LVAD-FactSheet.pdf Google Scholar As the success of LVAD therapy grows, it can be expected to see these patients return to the operating room with increasing frequency for noncardiac procedures. Anesthetic management of LVAD patients for open surgical procedures has been discussed in detail in prior literature 3 Morgan J.A. John R. Rao V. et al. Bridging to transplant with the HeartMate left ventricular assist device: The Columbia Presbyterian 12-year experience. J Thorac Cardiovasc Surg. 2004; 127: 1309-1316 Abstract Full Text Full Text PDF PubMed Scopus (96) Google Scholar , 4 Eckhauser A.E. Melvin W.V. Sharp K.W. Management of general surgical problems in patients with left ventricular assist devices. Am Surg. 2006; 72: 158-161 PubMed Google Scholar , 5 Oleyar M. Stone M. Neustein S.M. Perioperative management of a patient with a nonpulsatile left ventricular-assist device presenting for noncardiac surgery. J Cardiothorac Vasc Anesth. 2010; 24: 820-823 Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar ; however, there is a void concerning management for laparoscopic procedures. 6 Kartha V. Gomez W. Wu B. et al. Laparoscopic cholecystectomy in a patient with an implantable left ventricular assist device. Br J Anaesth. 2008; 100: 652-655 Crossref PubMed Scopus (49) Google Scholar The anesthetic management for laparoscopic gastric bypass in a patient with an LVAD is reported. Verbal consent was obtained from the patient before writing this case report.

455 Is Reduced Pump Speed Associated with Less Gastrointestinal Bleeding among Patients on Non-Pulsatile Left Ventricular Assist Devices?

Purpose: Acute right ventricular dysfunction occurs in the setting of RV infarction, post cardiotomy, post left ventricular assist device and post cardiac transplant. Isolated acute right heart failure is relatively infrequent, but is usually associated with poor prognosis. Mechanical circulatory support is required in some cases. This is a case report of the use of a novel percutaneous right ventrivular assist device, Impella RP (Abiomed, USA) in a patient who developed acute right heart failure post transplant. Methods and Materials: A 59 year old male received a HeartMate II (Thoratec Corp, USA) as a bridge to tranplant. Patient underwent orthotopic heart tranplant with a prolonged ischemic time of six hours. Primary graft dysfunction requiring ECMO support which was weaned off 2 days post. Unfortunately, pateint developed cardiogenic shock secondary to acute right ventricular failure. An Impella RP device was inserted via the right femoral vein, advanced into the right atrium, across the tricuspid valve and into the main pulmanary artery over a guidewire.

Comparative Analysis of von Willebrand Factor Profiles in Pulsatile and Continuous Left Ventricular Assist Device Recipients

A higher rate of nonsurgical bleeding has been observed in nonpulsatile left ventricular assist device (LVAD) recipients. von Willebrand factor (vWF) profiles were compared for nonpulsatile and pulsatile LVAD recipients to explore mechanisms that may contribute to the development of postimplant nonsurgical bleeding. The nonpulsatile mechanism may impair vWF function by creating a deficiency in vWF high molecular weight multimers (HMWMs), essential for hemostasis. High molecular weight multimer deficiency should result in low ristocetin cofactor (RCo) to vWF antigen ratios (vWF:RCo/vWF:Ag) because of impaired platelet (plt)-binding ability. von Willebrand factor profiles and HMWM were measured pre- and post-LVAD placement in 11 nonpulsatile (HeartMate II [HM II[) and 3 pulsatile (HeartMate XVE [HM XVE]) recipients. All the nonpulsatile LVAD recipients exhibited loss of HMWM 30 days postimplant. The vWF:RCo/vWF:Ag ratio was significantly lower after LVAD placement in the nonpulsatile group when compared with the pulsatile group. In addition, the vWF:RCo/vWF:Ag ratio decreased significantly from baseline 30 days postimplant within the nonpulsatile recipients. All nonpulsatile LVAD recipients had low vWF:RCo/vWF:Ag ratios 30 days post-LVAD even if the values were normal at baseline. These data suggest that nonpulsatile HM II recipients develop HMWM loss and impaired vWF platelet (plt)-binding ability after LVAD placement. Similar results were not observed in our small series of pulsatile HM XVE recipients. This finding could suggest a contributing factor to the increase in nonsurgical bleeding observed in nonpulsatile LVAD patients. Further investigation is ongoing to identify specific causes of vWF impairment.

002 Can non-pulsatile continuous-flow left ventricular assist devices confer physiologically desirable cardiac and physical functional benefits during peak exercise?

<h3>Introduction</h3> Left ventricular assist devices (LVADs) have been used as an effective therapeutic option in patients with advanced heart failure either as a bridge to transplantation, as destination therapy or as a bridge to recovery. Most recently it has been shown that the use of continuous-flow LVAD (HeartMate II) improves the rate of survival, quality of life, and functional capacity of patients as compared with the pulsatile-flow LVAD. To date, no study has reported how well HeartMate II can improve organ function and patients9 exercise ability. The present project aimed to assess cardiac and exercise performance of patients implanted with continuous-flow LVADs under two conditions: (i) optimal device support, and (ii) reduced device support. These results were compared with those of LVAD explanted (recovered) patients, heart transplant candidates and healthy controls. <h3>Methods</h3> Fifty-eight male patients, 18 implanted with a HeartMate II LVAD, 16 LVAD explanted patients and 24 heart transplant candidates (HTx) and 101 healthy controls performed graded cardiopulmonary exercise test with respiratory gas exchange and noninvasive (rebreathing) haemodynamic measurements. Twelve of the 18 LVAD implanted patients performed an additional cardiopulmonary exercise test with reduced LVAD support (pump speed reduced from optimal 9000–9600 revs/min to 6000 revs/min). <h3>Results</h3> At lower HeartMate II support, peak exercise cardiac power output was 39% lower (1.42±0.41 vs 2.31±0.50 W; p&lt;0.05), peak cardiac output 30% lower (8.6±2.31 vs 12.2±1.55 l/min; p&lt;0.05), and mean blood pressure 13% lower (74±7 vs 85±12 vs mmHg; p&lt;0.05). Exercise capacity was also diminished with 23% lower peak oxygen consumption (14.1±5.3 vs 18.2±4.5 ml/kg/min; p&lt;0.05) and 18% shorter exercise duration (516±179 vs 628±142 s; p&lt;0.05). Peak cardiac power output was significantly higher in the LVAD explanted than in the HTx and the LVAD implanted patients (HTx: 1.31±0.31 W; implanted: 2.31±0.50 W; explanted: 3.39±0.61 W; p&lt;0.01) as was peak cardiac output (HTx: 8.0±1.5; implanted: 12.2±1.55 explanted, 14.6±2.9 l/min; p&lt;0.01). Peak oxygen consumption was higher in the LVAD explanted than the HTx and the implanted patients (HTx, 12.5±2.5; implanted, 18.2±4.5; explanted, 28.2±5.0 ml/kg/min; p&lt;0.05) as was oxygen consumption at anaerobic threshold (p&lt;0.05). In the explanted cohort, 38% achieved peak cardiac power output and 69% peak oxygen consumption within the ranges of healthy controls. <h3>Conclusion</h3> We have shown for the first time that complementary to reported prognostic benefits, non-pulsatile continuous-flow LVAD pumps can confer cardiac functional benefits to patients with end-stage heart failure to derive improved exercise capacity, while those who recovered sufficiently to allow explantation of LVADs can even achieve cardiac and physical functional capacities nearly equivalent to those of healthy controls.

Effect of Pulsatile and Non-pulsatile Left Ventricular Assist Devices on the Renin-Angiotensin System in Patients with End-Stage Heart Failure

Left ventricular assist devices have been successfully used as a bridge to cardiac transplantation. Because many patients exhibit marked clinical improvement of their heart failure after LVAD implantation, we studied the physiological effect of pulsatile and non-pulsatile devices on the neurohormonal axis and exercise capacity. We prospectively included 20 patients (17 men, 3 women) undergoing LVAD implantation between November 2001 and January 2004. Ten patients (1 woman and 9 men) were treated with the non-pulsatile INCOR-LVAD (Berlin Heart(c)) and ten patients received the pulsatile EXCOR LVAD (Berlin Heart(c)). Blood samples for plasma renin activity (PRA) were taken once a week over a period of ten weeks. All blood samples were collected in the morning before mobilization. Blood pressure, body weight, fluid intake and urine production were measured once a day. All patients received standard hospital diet with no limitation in fluid intake. Body weight remained constant in both groups throughout the ten weeks' examination, and fluid intake and urine production were balanced in all patients. Although there was no significant difference in mean blood pressure (INCOR: 70 +/- 10 mmHg; EXCOR: 73 +/- 10 mmHg), plasma renin activity was substantially elevated in patients with non-pulsatile left ventricular support (INCOR: 94.68 +/- 33.97 microU/ml; EXCOR: 17.06 +/- 15.94 microU/ml; P < 0.05). Furthermore plasma aldosterone levels were significantly higher in patients supported by non-pulsatile INCOR LVAD (INCOR: 73.4 +/- 9.6 microg/ml; EXCOR: 20.6 +/- 4.6 microg/ml; P < 0.05). Our data suggest that pulsatile as well as non-pulsatile left ventricular assist devices are equally able to treat chronic heart failure. However pulsatile devices seem to have a greater impact on reversing the changes in plasma renin activity and might thus offer a greater advantage when recovery of left ventricular function is expected.

A novel non-invasive method to assess aortic valve opening in HeartMate II left ventricular assist device patients using a modified Karhunen-Loève transformation

Thrombus formation on or near the aortic valve has been reported in HeartMate II (Thoratec, Pleasanton, CA) left ventricular assist device (LVAD) patients whose aortic valves do not open. With an akinetic valve, thrombogenesis is more likely. Thrombus formation may lead to neurologic events, placing the patient at greater risk. Aortic valve stenosis and/or regurgitation have also been observed with akinetic aortic valves. Assessing aortic valve opening is crucial when optimizing rotations per minute (rpm) to minimize embolic risk and aortic valve stenosis but presently relies solely on echocardiography, intermittent decreases in rpms to force aortic valve opening, and monitoring of pulse pressure. We hypothesized the electrical current waveforms of the HeartMate II would reveal whether the aortic valve was opening due to pressure changes in the left ventricle to allow for continuous monitoring and control of aortic valve opening ratios. Electrical HeartMate II current waveforms of patients from 2008 to 2009 that were recorded at the time of echocardiograph procedures were analyzed using a modified Karhunen-Loève transformation with a training set of electrical waveforms from 8,860 HeartMate II electrical current recordings from 2001 to 2009. The study included 6 patients. The electrical current magnitude of the projection of the electrical current waveforms onto the training set's eigenvectors was statistically significantly greater in 4 of the 6 patients when the aortic valve was closed, confirmed by echocardiography. The 2 patients who did not have a large increase in the magnitude had mild aortic valve regurgitation. Electrical current analysis for rotary non-pulsatile pumps is a means to develop a physiologic feedback algorithm for an auto-mode, which currently does not exist. Constant regulation and optimization of rotary non-pulsatile LVADs would minimize patients' risk for neurologic events and aortic valve stenosis.