[Show abstract][Hide abstract] ABSTRACT: Left ventricular assist devices (LVADs) acutely decrease left ventricular wall stress. Thus, early postoperative levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) should decrease. This study investigated postoperative changes in NT-proBNP levels, the parameters related to changes, and the possible association with complications by performing a retrospective analysis of changes in daily NT-proBNP (pg/ml) levels from admission to discharge both before and after LVAD implantation in a tertiary referral center. For 72 patients implanted with HeartMate II LVADs, baseline NT-proBNP levels were elevated at 3,943 ng/ml (interquartile range 1,956 to 12,964). Preoperative stabilization led to marked decreases in NT-proBNP. Levels peaked 3 days after surgery and subsequently decreased. Patients with complicated postoperative courses had higher early postoperative elevations. By discharge, NT-proBNP decreased markedly but was still 2.83 (1.60 to 5.76) times the age-based upper limit of normal. The 26% reduction in NT-proBNP between admission and discharge was due mostly to the preoperative reductions and not those induced by the LVAD itself. The decrease was not associated with decreases in LV volume. In conclusion, preoperative treatment reduces NT-proBNP values. The magnitude of early postoperative changes is related to the clinical course. Levels at discharge remain markedly elevated and similar to values after preoperative stabilization despite presumptive acute LV unloading.
The American Journal of Cardiology 08/2014; 114(8). DOI:10.1016/j.amjcard.2014.07.056 · 3.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cardiac output (CO) assessment is important in treating patients with heart failure. Durable left ventricular assist devices (LVAD) provide essentially all CO. In currently used LVADs estimated device flow is generated by a computerized algorithm. However LVAD flow estimate may be inaccurate in tracking true cardiac output. We correlated LVAD (HeartMateII) flow with thermodilution CO during postoperative care (day 2-10 after implant) in 81 patients (5616 paired measurements). LVAD flow and CO correlated with a low correlation coefficient (r=0.42). LVAD readings were lower than CO measurements by about 0.36L/min, trending for larger difference with higher values. LVAD flow measurements showed less temporal variability compared with CO. Grouping for simultaneous measured blood pressure (BP<60, 60-70, 70-80, 80-90 and ≥90), the correlation of CO with LVAD flow differed (R=0.42, 0.67, 0.48, 0.32, 0.32 respectively). Indicating better correlation when mean blood pressure is 60-70mmHg. LVAD flow generally trends with measured cardiac output, but large variability exists, hence flow measures should not be assumed to equal with cardiac output. Clinicians should take into account variables such as high CO, BP and opening of the aortic valve when interpreting LVAD flow readout. Direct flow sensors incorporated in the LVAD system may allow for better estimation.
ASAIO journal (American Society for Artificial Internal Organs: 1992) 07/2014; 60(5). DOI:10.1097/MAT.0000000000000119 · 1.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Continuous flow left ventricular assist devices (LVADs) are used with good outcome. However, acute intravascular hemolysis due to thrombus in the pump remains a clinical challenge. We screened for LVAD-related intravascular hemolysis among 115 consecutive patients surviving HeartMateII implantation and investigated the role of medical therapy in resolving the hemolysis. Hemolytic events were identified in 7% of patients, 2-26 months after implant, manifested by peak lactate dehydrogenase (LDH) levels >6 times normal. With the institution of heparin and enhanced antiplatelet therapy, LDH levels receded rapidly reaching a stable trough level near baseline within 2 weeks with the resolution of clinical symptoms except in one patient who required additional therapy with tissue plasminogen activator (tPA). Complications included transient renal failure, one splenic infarct, and a cerebrovascular attack after tPA. The acute event of hemolysis resolved with medical therapy, and all were successfully discharged. However, recurrent hemolysis was common (6/8 patients over the next 1-7 months). At the end of follow-up, three patients were transplanted, one patient died refusing LVAD exchange for recurrent hemolysis, and 4 remained alive on LVAD support. Medical treatment with intensification of anticoagulation can be effective in resolving the acute hemolytic event. However, a definitive long-term strategy should be planned because the recurrence rate is high.
ASAIO journal (American Society for Artificial Internal Organs: 1992) 12/2013; 60(1). DOI:10.1097/MAT.0000000000000012 · 1.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Left ventricular assist devices (LVAD) as a bridge (BTT) to heart transplantation (HTX) may be limited by the formation of anti-human leukocyte antigen antibodies. Whether sensitization occurs with continuous axial flow LVAD implant as assessed by single antigen bead (SAB) assay is unknown. METHODS: Cytotoxic panel-reactive antibody (PRA) and SAB assays were analyzed in HTX recipients undergoing LVAD implant as a BTT. Sensitization was defined as peak anti-human leukocyte antigen antibody values of more than 2000 mean fluorescence intensity because these values have been found to correlate with flow cytometric crossmatch results. RESULTS: LVADs were implanted as BTT in 30 patients. There were 7% (2 of 30) of patients before LVAD implant and no patients after LVAD implant with PRA more than 10%. However, 20% (6 of 30) of patients before LVAD and 53% (16 of 30) after LVAD were sensitized as measured by SAB (P=0.024). At HTX, 47% (14 of 30) of patients remained sensitized. A positive virtual crossmatch was observed in 28% (4 of 14) of the sensitized patients at HTX. There was no difference between the sensitized and nonsensitized groups (P>0.4 for all) in usage of blood products (6411 vs. 6339 units) and time to HTX (28,663 vs. 25,748 days), and 1 year after HTX, there were no differences in rejection (total rejection score 0.30 vs. 0.37) and survival (93% vs. 88%). CONCLUSION: Allosensitization after LVAD is common despite cytotoxic PRA being negative. One year after HTX, this sensitization does not translate into increased acute cellular or antibody-mediated rejection or reduced survival.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVES: The purpose of this study was to determine the occurrence and causes of readmissions after implantation of axial flow left ventricular assist device (LVAD). BACKGROUND: Based on the REMATCH (Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure) study experience, readmissions after LVAD implantation are thought to be frequent. METHODS: We retrospectively analyzed admissions to our facility in a cohort of 115 patients implanted between January 2008 and July 2011 with the HeartMate II axial flow LVAD, of whom 42 were bridged to transplant. To account for repeated events, Andersen-Gill models were used to determine possible predictors. RESULTS: The patients were followed for 1.4 ± 0.9 years. There were 224 readmissions in 83 patients. The overall readmission rate was 1.64 ± 1.97 per patient-year of follow-up. The readmission rate for the first 6 months was 2.0 ± 2.3 and decreased to 1.2 ± 2.1 during subsequent follow-up. Leading causes were bleeding (66 readmissions in 34 patients), mostly gastrointestinal bleed (51 in 27 patients), cardiac (51 in 36 patients, most for HF or arrhythmia), infections (32 in 25 patients) of which 6 were pump related, and thrombosis (20 in 15 patients) including 13 readmissions due to hemolysis. Preoperative variables associated with (fewer) readmissions in a multivariate model include residence within our hospital-extended referral zone of Minnesota and the neighboring states (hazard ratio: 0.66; 95% confidence interval: 0.48 to 0.91; p = 0.011), hemoglobin (hazard ratio: 0.91, 95% confidence interval: 0.84 to 0.99; p = 0.027) and N-terminal pro-B-type natriuretic peptide (hazard ratio: 0.98; 95% confidence interval: 0.96 to 1.0 per 1,000-unit increase, p = 0.022). C-statistic for the model: 0.63. CONCLUSIONS: Readmission rates after axial flow LVAD implantation decrease during the first 6 months and then stabilize. The leading causes are bleeding, cardiac (heart failure and arrhythmia), infections, and thrombosis.
Journal of the American College of Cardiology 11/2012; 61(2). DOI:10.1016/j.jacc.2012.09.041 · 15.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The goal of this study was to describe the predictors and significance of poor exercise tolerance after left ventricular assist device (LVAD) implantation. Despite LVAD therapy, some patients continue to exhibit exercise intolerance. The predictors and outcomes of these patients are unknown. A retrospective review of 65 LVAD recipients who performed 6-minute walk tests was conducted. Patients walking <300 m were considered to have poor exercise tolerance. Twenty patients exhibited poor exercise tolerance (221 ± 45 m), compared to 45 patients with better exercise tolerance (406 ± 76 m). Postoperatively, poor performers were not easily identified by functional symptoms alone, because 42% of these patients reported New York Heart Association functional class I or II symptoms. Preoperative New York Heart Association class, inotrope therapy, and intra-aortic balloon pump use were similar between the 2 groups. Multivariate analysis using all adequately powered (n >50) univariate predictors identified diabetes mellitus (odds ratio 10.493, p = 0.003) and elevated 1-month right atrial pressure (odds ratio 2.985 for every 5 mm Hg, p = 0.003) as significant predictors of poor performance (<300 m; area under the curve 0.85). The poorly performing group had increased mortality (p = 0.011), with 21% increased risk for overall mortality for every 10 m short of 300 m (fitted Cox model: hazard ratio 1.211, p = 0.0001). The distance walked in meters in a postoperative 6-minute walk test was the strongest predictor of late post-LVAD mortality (p = 0.0002). In conclusion, despite similar severity of heart failure preoperatively, some LVAD recipients may have persistent exercise intolerance postoperatively as assessed by the 6-minute walk test that is independently associated with subsequent reduced survival.
The American journal of cardiology 07/2012; 110(9):1322-8. DOI:10.1016/j.amjcard.2012.06.036 · 3.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A universal loss of von Willebrand factor (vWF) high-molecular-weight multimers (HMWM) has been demonstrated in continuous-flow left ventricular assist device (HeartMate II) recipients. However, no reliable clinical or laboratory predictors for an increased bleeding tendency in this patient population have been identified. This study evaluated the ability of a new automated latex particle-enhanced immunoturbidimetric vWF activity assay (ALPEIVA) to predict non-surgical bleeding risk in HeartMate II recipients.
As part of a prospective multicenter trial, pre-surgical, 7-day, and 30-day post-implantation blood samples were collected from 24 patients. ALPEIVA-assessed vWF activities were compared among patients with and without non-surgical bleeding complications after HeartMate II implantation. Additional laboratory testing included factor VIII activity (FVIII:C), vWF antigen (vWFAg), vWF ristocetin cofactor activity (vWF:RCo), and vWF multimer analysis.
All 24 patients had HMWM losses after HeartMate II implantation. Five patients (20%) developed non-surgical bleeding complications between 14 days and 6 months after HeartMate II implantation. Among various laboratory variables, only mean ALPEIVA/vWFAg ratios (referred to as the "bleeding ratio") were significantly lower in patients with clinically relevant bleeding (mean, 0.70 ± 0.06) compared with patients without bleeding (mean, 0.78 ± 0.09; p = 0.02) when measured at 30 days.
The post-surgical bleeding ratio could potentially predict non-surgical bleeding risk and guide anti-platelet and anti-coagulation strategies in HeartMate II recipients.
The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation 04/2012; 31(7):750-6. DOI:10.1016/j.healun.2012.02.032 · 5.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objectives: The purpose of this study was to determine the occurrence and causes of readmissions after implantation of axial flow left ventricular assist device (LVAD).
Background: Based on the REMATCH (Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure) study experience, readmissions after LVAD implantation are thought to be frequent.
Methods: We retrospectively analyzed admissions to our facility in a cohort of 115 patients implanted between January 2008 and July 2011 with the HeartMate II axial flow LVAD, of whom 42 were bridged to transplant. To account for repeated events, Andersen-Gill models were used to determine possible predictors.
Results: The patients were followed for 1.4+-0.9 years. There were 224 readmissions in 83 patients. The overall readmission rate was 1.64+-1.97 per patient-year of follow-up. The readmission rate for the first 6 months was 2.0+-2.3 and decreased to 1.2+-2.1 during subsequent follow-up. Leading causes were bleeding (66 readmissions in 34 patients), mostly gastrointestinal bleed (51 in 27 patients), cardiac (51 in 36 patients, most for HF or arrhythmia), infections (32 in 25 patients) of which 6 were pump related, and thrombosis (20 in 15 patients) including 13 readmissions due to hemolysis. Preoperative variables associated with (fewer) readmissions in a multivariate model include residence within our hospital-extended referral zone of Minnesota and the neighboring states (hazard ratio: 0.66; 95% confidence interval: 0.48 to 0.91; p �=0.011), hemoglobin (hazard ratio: 0.91, 95% confidence interval: 0.84 to 0.99; p=0.027) and N-terminal pro–B-type natriuretic peptide (hazard ratio: 0.98; 95% confidence interval: 0.96 to 1.0 per 1,000-unit increase, p=0.022). C-statistic for the model: 0.63.
Conclusions: Readmission rates after axial flow LVAD implantation decrease during the first 6 months and then stabilize. The leading causes are bleeding, cardiac (heart failure and arrhythmia), infections, and thrombosis.
The Journal of Heart and Lung Transplantation 04/2012; 31(4):S196. DOI:10.1016/j.healun.2012.01.578 · 5.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aortic pseudoaneurysm is a rare complication after blunt chest trauma or cardiac surgical procedures and can occur at the site of cannulation or root vent insertion on the ascending aorta. These pseudoaneurysms have the potential to expand, erode, and rupture, and detecting this condition before complications occur is the key to successful management. We had replaced the mitral valve with a 31-mm bioprosthesis in an 82-year-old patient and repaired an ascending aorta aneurysm, but a computed tomography scan on postoperative day 18 revealed a pseudoaneurysm at the site of the previous aortic cannulation. Because of the patient's advanced age and multiple comorbidities, we sealed off the neck of the pseudoaneurysm with a 12-mm Amplatzer Vascular Plug in the interventional cardiology suite instead of subjecting her to a surgical repair involving redo sternotomy and a period of circulatory arrest. Deployment of the Amplatzer plug effectively shut off flow into the pseudoaneurysm, and the patient recovered well. Although the optimal management strategy for aortic pseudoaneurysms is a matter of controversy, endovascular interventions may be a safer alternative to surgery for patients with multiple comorbidities.
Heart Surgery Forum 02/2012; 15(1):E34-6. DOI:10.1532/HSF98.20111099
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to determine renal outcomes after left ventricular assist device (LVAD) implantation.
Renal dysfunction before LVAD placement is frequent, and it is unclear whether it is due to primary renal disease or to poor perfusion.
A retrospective single-center analysis was conducted in 83 consecutive patients implanted with HeartMate II continuous-flow LVADs (Thoratec Corp., Pleasanton, California). Calculated glomerular filtration rate (GFR) was assessed on admission and 1, 3, and 6 months after implantation. To define predictors for improvement in GFR, clinical variables were examined in patients with decreased renal function (GFR <60 ml/min/1.73 m(2)) before LVAD, surviving and dialysis-free at 1 month (n = 44).
GFR significantly increased from admission (53.2 ± 21.4 ml/min/1.73 m(2)) to 1 month after LVAD implantation (87.4 ± 27.9 ml/min/1.73 m(2)) (p < 0.0001). Subsequently, at 3 and 6 months, GFR remained significantly (p < 0.0001) above pre-LVAD values. Of the 51 patients with GFRs <60 ml/min/1.73 m(2) before LVAD surviving at 1 month, 34 (67%) improved to GFRs >60 ml/min/1.73 m(2). Univariate pre-operative predictors for improvement in renal function at 1 month included younger age (p = 0.049), GFR improvement with optimal medical therapy (p < 0.001), intra-aortic balloon pump use (p = 0.004), kidney length above 10 cm (p = 0.023), no treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (p = 0.029), higher bilirubin (p = 0.002), higher Lietz-Miller score (p = 0.019), and atrial fibrillation (p = 0.007). Multivariate analysis indicated pre-operative improved GFR (slope = 0.5 U per unit improved; 95% confidence interval: 0.2 to 0.8; p = 0.003), atrial fibrillation (slope = 27; 95% confidence interval: 8 to 46; p = 0.006), and intra-aortic balloon pump use (slope = 14; 95% confidence interval: 2 to 26; p = 0.02) as independent predictors.
In most patients with end-stage heart failure considered for LVAD implantation, renal dysfunction is reversible and likely related to poor renal perfusion.
Journal of the American College of Cardiology 01/2012; 59(1):26-36. DOI:10.1016/j.jacc.2011.09.038 · 15.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Continuous-flow left ventricular assist devices (LVADs) such as the HeartMate II have become the therapy of choice in patients with end-stage heart failure. The aim of this study is to report the outcomes in patients receiving the HeartMate II LVAD at a single center and review the lessons learned from this experience.
From June 2005 to June 2010, 130 consecutive patients received the HeartMate II LVAD. Of these, 102 were bridge-to-transplant (BTT), 17 destination therapy, and 11 exchanges for failed HeartMate XVE. This study focuses on the 102 BTT patients. The HeartMate II was approved by the US Food and Drug Administration (FDA) as BTT in April 2008 and 64 patients received this device as BTT since that date. We review our experience with the device as BTT and report on patient survival and adverse events as well as the impact of FDA approval on outcomes.
Overall, mean age was 52.6 ± 12.8 years; 26 (25.5%) were female. Disease etiology was ischemic in 58, nonischemic in 36, and other in 8. Overall, 30-day, 6-month, and 1-year survival for the BTT patients was 95.1%, 83.5%, and 78.8%, respectively. The 6-month survival in 38 patients in the clinical trial (pre-FDA) was 88.8% and was not statistically significant compared with the 76.2% 6-month survival in the 64 patients in the post-FDA approval period (p value = 0.1). Major adverse events among the 102 BTT patients included right ventricular failure in 5 (4.9%), LVAD driveline infections in 25 (24.5%), neurologic events in 10 (9.8%), and gastrointestinal bleeding in 18 (17.6%) patients. In addition, 1 patient (0.98%) had pump thrombus requiring device replacement.
Despite significant morbidity, use of the HeartMate II LVAD as BTT provides excellent hemodynamic support and is associated with excellent survival and low mortality. In addition, there needs to be improvement and focused strategies in the areas of gastrointestinal bleeding, driveline infections, and adverse neurologic events for these devices to be able to provide a real long-term alternative to heart transplantation.
The Annals of thoracic surgery 11/2011; 92(5):1593-9; discussion 1599-600. DOI:10.1016/j.athoracsur.2011.06.081 · 3.65 Impact Factor