Reasons for, and outcomes of patients who were referred for a ventricular assist device but were declined: the recent era forgotten ones.

BACKGROUND: Ventricular assist devices (VADs) have a proven survival benefit in select patients with advanced heart failure, yet many patients considered for implantation are declined for various reasons. The outcome of these patients is obscure owing to their exclusion from recent VAD studies. We aim to compare the outcomes of patients who received a VAD to those who did not. METHODS: For this study, the Artificial Heart Program's database at Intermountain Medical Center was queried from 2006 to 2012 for patients referred for a VAD. Kaplan-Meier survival analysis was performed with log-rank test determining significance. RESULTS: Of 232 patients included, 118 patients received a VAD and 114 patients did not. The prevailing reason for VAD decline in eligible and willing patients was due to pre-existing illness (39%). Mortality was higher in non-VAD vs. VAD patients (58.8% vs. 35.6%, p < 0.001) with a median time-to-death of 67 (IQR:12-314) and 301 (IQR:136-694) d, respectively (p = 0.007). CONCLUSIONS: In the current era of non-pulsatile VADs, mortality of patients who are considered but not implanted remains high. Additionally, mortality of these patients occurred much sooner. Educational efforts ensuring timely referral for VAD therapy are important to maximize the number of patients who may benefit.

Ultraviolet Radiation Affects Thoratec HeartMate II Driveline Mechanical Properties: A Pilot Experiment.

Longevity and quality of life for left ventricular assist device (LVAD) patients are plagued by driveline exit site infections. Ultraviolet (UV) radiation, a current treatment in wound healing clinics, could potentially treat LVAD exit site infections. However, the effect of UV radiation on the tensile properties of HeartMate II (HMII) driveline material is unknown. The sleeve of a single HMII driveline was distributed into six exposure groups (n = 10/group). The six groups were further divided into two treatment cohorts designed to replicate wound treatment schedules of postimplant LVAD patients. Strip biaxial tensile tests were performed on both unexposed and exposed samples to analyze changes in material elasticity (Young's modulus), point of deformation (yield strength), and breaking point. Our data suggest that UV exposure changes the elasticity of the HMII driveline. However, the material endured aberrantly large forces and the properties remained within the safety threshold of device performance. This study warrants further examination of the effect of UV light on driveline material, to determine safety, reliability, and efficacy of UV treatment on exit site infections.

Comparing velour versus silicone interfaces at the driveline exit site of HeartMate II devices: infection rates, histopathology, and ultrastructural aspects.

BACKGROUND: Driveline exit site (DLES) infection is a major complication of ventricular assist devices (VADs). Differences in the sheath material interfacing with exit site tissue appear to affect healing time and infection risk more than site hygiene, but the mechanistic basis for this is not clear. METHODS: Health record data from Utah Artificial Heart Program patients with HeartMate II (HMII) devices implanted from 2008 to 2012 were retrospectively reviewed, with particular attention to interface type, incorporation (healing) time, and infections. Tissue samples from the DLES were collected at the time of VAD removal in a small subset. These samples were examined by routine histology and environmental scanning electron microscopy (ESEM). RESULTS: Among 57 patients with sufficient data, 15 had velour interfaces and 42 had silicone. Indications for and duration of support were similar between the groups. The silicone group had shorter incorporation time (45 ±22 vs. 56 ±34 days, P=.17) and fewer DLES infections (20% vs. 1.7%, P=.026, for patient infections and 0.0340 vs. 0.166, P=.16, for infections per patient-year). Tissues from five patients, three with velour, were examined. Velour interfaces demonstrated more hyperkeratosis, hypergranulosis, and dermal inflammation. By ESEM, the silicone driveline tracts appeared relatively smooth and flat, whereas the velour interface samples were irregular with deep fissures and globular material adhering to the surface. CONCLUSIONS: Using the silicone portion of the HMII driveline at the DLES was associated with fewer infections and a trend toward faster healing in this small retrospective series. Whether the intriguing microscopic differences directly account for this needs further study on a larger scale.

Magnitude and time course of changes induced by continuous-flow left ventricular assist device unloading in chronic heart failure: insights into cardiac recovery.

OBJECTIVES: This study sought to prospectively investigate the longitudinal effects of continuous-flow left ventricular assist device (LVAD) unloading on myocardial structure and systolic and diastolic function. BACKGROUND: The magnitude, timeline, and sustainability of changes induced by continuous-flow LVAD on the structure and function of the failing human heart are unknown. METHODS: Eighty consecutive patients with clinical characteristics consistent with chronic heart failure requiring implantation of a continuous-flow LVAD were prospectively enrolled. Serial echocardiograms (at 1, 2, 3, 4, 6, 9, and 12 months) and right heart catheterizations were performed after LVAD implant. Cardiac recovery was assessed on the basis of improvement in systolic and diastolic function indices on echocardiography that were sustained during LVAD turn-down studies. RESULTS: After 6 months of LVAD unloading, 34% of patients had a relative LV ejection fraction increase above 50% and 19% of patients, both ischemic and nonischemic, achieved an LV ejection fraction ≥ 40%. LV systolic function improved as early as 30 days, the greatest degree of improvement was achieved by 6 months of mechanical unloading and persisted over the 1-year follow up. LV diastolic function parameters also improved as early as 30 days after LVAD unloading, and this improvement persisted over time. LV end-diastolic and end-systolic volumes decreased as early as 30 days after LVAD unloading (113 vs. 77 ml/m(2), p < 0.01, and 92 vs. 60 ml/m(2), p < 0.01, respectively). LV mass decreased as early as 30 days after LVAD unloading (114 vs. 95 g/m(2), p < 0.05) and continued to do so over the 1-year follow-up but did not reach values below the normal reference range, suggesting no atrophic remodeling after prolonged LVAD unloading. CONCLUSIONS: Continuous-flow LVAD unloading induced in a subset of patients, both ischemic and nonischemic, early improvement in myocardial structure and systolic and diastolic function that was largely completed within 6 months, with no evidence of subsequent regression.

Differential impact on post-transplant outcomes between pulsatile- and continuous-flow left ventricular assist devices.

BACKGROUND: The HeartMate II (HMII) left ventricular assist device (LVAD) has proven reliable and durable and has become the preferred choice for bridge to transplant therapy (BTT) when compared with the pulsatile HeartMate XVE (XVE). In this study, we compared the post-transplant (PTx) outcomes between XVE and HMII using a large national data registry. METHODS: The Organ Procurement and Transplantation Network (OPTN)/United Network for Organ Sharing (UNOS) Thoracic Registry database was queried for all patients implanted with either an XVE or an HMII as BTT during 2004-2009. Statistical analysis between XVE and HMII were performed using Kaplan-Meier survival analysis and Cox regression analyses. RESULTS: A total of 673 patients were implanted with the XVE and 484 with HMII. When adjusted for age, gender, ethnicity, intra-aortic balloon pump, ventilator, inotropes, dialysis, body mass index, creatinine, bilirubin, transfusion, pulmonary capillary wedge, and pulmonary arterial pressures, the HMII had similar one- and three-yr survival (hazard ratio = 0.95, CI = 0.64, 1.42) and rejection-free survival PTx compared to XVE. The XVE group had more early incidences of allograft rejection (AR) and hospitalization for infection (HI). CONCLUSIONS: Compared to XVE, patients with HMII have similar one- and three-yr survival after heart transplantation with less risk of early graft rejection and significant infection. With a strong shift toward use of continuous-flow LVADs, PTx outcomes are expected to continue to improve.

End-of-life decision making and implementation in recipients of a destination left ventricular assist device.

BACKGROUND: The use of left ventricular assist devices (LVADs) as destination therapy (DT) is increasing and has proven beneficial in prolonging survival and improving quality of life in select patients with end-stage heart failure. Nonetheless, end-of-life (EOL) issues are inevitable and how to approach them underreported. METHODS: Our DT data registry was queried for eligible patients, defined as those individuals who actively participated in EOL decision making. The process from early EOL discussion to palliation and death was reviewed. We recorded the causes leading to EOL discussion, time from EOL decision to withdrawal and from withdrawal to death, and location. Primary caregivers were surveyed to qualify their experience and identify themes relevant to this process. RESULTS: Between 1999 and 2009, 92 DT LVADs were implanted in 69 patients. Twenty patients qualified for inclusion (mean length of support: 833 days). A decrease in quality of life from new/worsening comorbidities usually prompted EOL discussion. Eleven patients died at home, 8 in the hospital and 1 in a nursing home. Time from EOL decision to LVAD withdrawal ranged from <1 day to 2 weeks and from withdrawal until death was <20 minutes in all cases. Palliative care was provided to all patients. Ongoing assistance from the healthcare team facilitated closure and ensured comfort at EOL. CONCLUSIONS: With expanding indications and improved technology, more DT LVADs will be implanted and for longer durations, and more patients will face EOL issues. A multidisciplinary team approach with protocols involving DT patients and their families in EOL decision making allows for continuity of care and ensures dignity and comfort at EOL.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Obesity and left ventricular assist device driveline exit site infection.

Driveline exit site (DLES) infection is a persistent problem among the left ventricular assist device (LVAD) patients. This study investigated the relationship between obesity and DLES infection. Records of LVAD patients at two institutions from January 1999 to January 2009 were queried. Results were analyzed using t tests. Those with LVAD support > or =90 days were included. The body mass index (BMI) of each patient was measured at the time of implant and at the conclusion of LVAD support or currently, if the patient was ongoing. Other data included preimplant age, ejection fraction, blood urea nitrogen, creatinine, diabetes, New York Heart Association class, pulmonary capillary wedge pressure, VO2 max, and inotrope therapy. The 118 patients who qualified for the study were placed in an infection group (n = 36) or in the control group (n = 82). Both groups had similar preimplant characteristics. Variables with differences statistically significant between the groups included duration of LVAD support, indication for support, device type, and BMI. Patients who developed DLES infections had a significantly higher BMI and continued weight gain over the course of LVAD therapy compared with the control group. Although this association requires further study, implications for clinical practice may include the provision of nutrition and exercise counseling for patients undergoing LVAD therapy, especially if overweight. These results may warrant increased measures to prevent and treat infection in the preimplant and postimplant periods.

Noninvasive predictor of HeartMate XVE pump failure by neural network and waveform analysis.

Patients increasingly require longer durations of left ventricular assist device (LVAD) therapy. Despite a recent trend toward continuous flow VADs, the HeartMate XVE is still commonly used, but its longevity remains a significant limitation. Existing surveillance methods of pump failure often give inconclusive results. XVE electrical current waveforms were collected regularly (2001-2008) and sorted into quartiles according to number of days until pump failure (Q1, 0-34; Q2, 34-160; Q3, 160-300; and Q4, 300-390 days). Thoratec waveform files were converted into text files. The 10-second electrical current, voltage waveform was identified and isolated for analysis. Waveforms were analyzed by principal component analysis (PCA) and with a fast Fourier transform. Quartiles were compared with analysis of variance (ANOVA). Waveforms (n = 454) were collected for 21 patients with failed pumps. An artificial neural network was used to predict pump failure within 30 days from the waveform characteristics identified though signal processing.

Prior human leukocyte antigen-allosensitization and left ventricular assist device type affect degree of post-implantation human leukocyte antigen-allosensitization.

Left ventricular assist device (LVAD) implantation before heart transplantation has been associated with formation of antibodies directed against human leukocyte antigens (HLA), often referred to as sensitization. This study investigated whether prior sensitization or LVAD type affected the degree of post-implantation sensitization. The records of consecutive HeartMate (HM) I and HM II LVAD patients were reviewed. Panel reactive antibody (PRA) was assessed before LVAD implantation and biweekly thereafter. Sensitization was defined as PRA > 10%, and high-degree sensitization was defined as PRA > 90%. An HM LVAD was implanted in 64 patients, and 11 received a HM II LVAD as a bridge to transplant. Ten HM I patients (16%) were sensitized before LVAD implantation (HM I-S), and 54 (84%) were not (HM I-Non-S). Nine HM I-S patients (90%) became highly sensitized (PRA > 90%) compared with 9 HM I-Non-S patients (16.7%; p < 0.001). The PRA remained elevated (> 90%) in 8 of the 9 (88.9%) highly sensitized HM I-S patients vs 5 of the 9 (55.6%) HM I-Non-S highly sensitized patients. The PRA levels in the rest of the HM I-S highly sensitized patients declined from 93% +/- 4% to 55% +/- 15% (p = 0.01). Among the 11 HM II patients, 1 (9%) was sensitized before LVAD implantation (PRA, 40%) and the PRA moderately increased to 80%. No other HM II patient became sensitized after implantation. Thus, 1 of 11 (9%) HM II patients became sensitized compared with 29 of 64 (45%) HM I patients (p = 0.04). Pre-sensitized patients are at higher risk for becoming and remaining highly HLA-allosensitized after LVAD implantation. The HeartMate II LVAD appears to cause less sensitization than HeartMate I.