Left ventricular assist device malfunction: a systematic approach to diagnosis.

OBJECTIVES: A protocol was designed to diagnose the common malfunctions of a left ventricular assist device (LVAD). BACKGROUND: Mechanical circulatory support, primarily with an LVAD, is increasingly used for treatment of advanced heart failure (HF). Left ventricular assist device dysfunction is a recognized complication; but heretofore, a systematic method to accurately diagnose LVAD dysfunction has not been thoroughly described. METHODS: We developed a catheter-based protocol designed to characterize a normally functioning LVAD and diagnose multiple types of dysfunction. A total of 15 studies of 10 patients supported with an LVAD were reviewed. All patients had been evaluated due to concerns regarding LVAD dysfunction. RESULTS: Of 15 examinations performed, 11 documented severe LVAD inflow valve regurgitation. One of these cases proved to have coexistent severe mitral valve regurgitation. One case was diagnosed with distortion of the LVAD outflow graft. One case of suspected embolization from the pumping chamber excluded the outflow graft as the source of emboli. One study had aortic insufficiency. CONCLUSIONS: As LVAD use for treatment of end-stage HF becomes widespread and durations of support are extended, dysfunction will be increasingly prevalent. This catheter-based protocol provided a practical method to diagnose multiple causes of LVAD dysfunction.

Outcome of noncardiac surgery in patients with ventricular assist devices.

An increasing number of patients are living with ventricular assist devices (VADs). Many of these patients will require noncardiac surgery for conditions not directly related to their VADs. The aim of this study was to assess the risks and outcomes of noncardiac surgery in these patients. Perioperative and follow-up data from patients with VADs who underwent noncardiac surgery from 1993 to 2006 were analyzed. In that period, 184 VADs were implanted in 155 patients. Thirty-seven patients (24%) subsequently underwent 59 noncardiac surgeries. The mean duration of VAD support before surgery was 229 days. Bleeding was the most common postsurgical complication (10%), necessitating reexploration in 20% of abdominal surgeries. Thirty-day mortality was 12%. No deaths were caused by direct complications of surgery. Successful transplantation occurred in 72% of bridge to transplantation patients who required noncardiac surgery, compared with 71% of these patients who did not require noncardiac surgery (relative risk 1.0, p = 0.9). The average duration of VAD support after noncardiac surgery for destination therapy patients was 324 days, most of which time was spent at home. In conclusion, outcomes after noncardiac surgery in patients with VADs are favorable, and most patients continue to benefit from the intended purpose of mechanical circulatory support after recovering from noncardiac surgery.

Improving outcomes with long-term "destination" therapy using left ventricular assist devices.

OBJECTIVE: Destination therapy experience using long-term left ventricular assist devices was analyzed relative to the benchmark Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure trial to evaluate the potential for improving outcomes with this groundbreaking therapy for advanced heart failure. METHODS: The largest single-center experience with destination therapy in the United States (Utah Artificial Heart Program, LDS Hospital, Salt Lake City, UT) was retrospectively analyzed. All destination therapy recipients (n = 23) presented with chronic, advanced heart failure, meeting indications for destination therapy adopted from the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure trial. All received HeartMate left ventricular assist devices (Thoratec Corp, Pleasanton, Calif), with 87% receiving an improved XVE model. Advanced practice guidelines were implemented using a multidisciplinary approach. Survivals (Kaplan-Meier, log-rank analyses) and adverse events (Poisson regression) were compared with those of the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure left ventricular assist device group (n = 68). RESULTS: Survival in the destination therapy group was significantly increased (P = .007), with an overall reduction in mortality of 66%. The 2-year survival was 77% for destination therapy compared with 29% for the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure left ventricular assist device group (P < .0001). The 1-year survival was 77% for destination therapy compared with the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure left ventricular assist device rate of 52% (P = .036). Adverse events decreased by 38% (3.90 per patient-year in the destination therapy group compared with the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure left ventricular assist device rate of 6.32). Factors related to severity of illness met Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure-like criteria for both groups. CONCLUSIONS: This analysis provides evidence that long-term destination therapy can be improved well beyond the pioneering experience of the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure trial. With continued evolution of devices, management, and patient selection, outcomes approaching those of heart transplantation may be possible.

Prevalence and risks of allosensitization in HeartMate left ventricular assist device recipients: the impact of leukofiltered cellular blood product transfusions.

OBJECTIVE: Allosensitization of left ventricular assist device recipients has been associated with perioperative transfusion of cellular blood products. The relative sensitizing contribution of leukofiltered cellular blood products, however, remains unclear. We investigated the pattern of sensitization in left ventricular assist device recipients in relation to cellular blood product transfusions received. METHODS: Seventy-one consecutive nonsensitized recipients of the HeartMate left ventricular assist device (Thoratec Corporation, Pleasanton, Calif) as a bridge to transplantation were reviewed. Panel-reactive HLA antibody levels at consecutive times after device implantation were correlated with perioperative cellular blood product transfusions. RESULTS: Fifty-four patients received leukofiltered cellular blood products (transfused), whereas 17 patients received only fresh-frozen plasma (nontransfused). Among nontransfused patients, 58.8% (10/17) became sensitized during mechanical support, versus 35.2% of transfused patients (19/54, P = .15). There was a trend toward more sensitization during the 12 weeks after device placement in nontransfused patients. Kaplan-Meier analysis revealed significantly more sensitization in nontransfused patients than in transfused patients, despite equal rates of transplantation (P = .05). A dose-response analysis revealed significant trends toward less sensitization and lower peak panel-reactive antibody level with more cellular blood product transfusions (P = .04). Multivariate Cox regression revealed only increasing transfusions to be associated with a reduced risk of sensitization (hazard ratio 0.18, P = .01). CONCLUSIONS: Sensitization becomes more prevalent with increasing length of support. Avoidance of perioperative leukocyte-filtered cellular blood product transfusions does not decrease the incidence or degree of HLA sensitization. Conversely, cellular blood product transfusions may be associated with lessened alloimmunization and may mitigate the sensitization seen in recipients of the HeartMate left ventricular assist device as a bridge to transplantation.

Hospital costs for left ventricular assist devices for destination therapy: lower costs for implantation in the post-REMATCH era.

BACKGROUND: The use of left ventricular assist devices (LVADs) as an alternative to transplant, or destination therapy (end of life support), is an increasingly important option for patients with end-stage heart failure. Prior studies have examined hospital costs for LVAD implants performed during investigational studies (e.g., REMATCH), but none has been published since that trial was completed. METHODS: We performed a retrospective analysis of 23 consecutive patients who had a HeartMate XVE pump implanted as destination therapy at 2 high-volume ventricular assist device implant centers after US Food and Drug Administration approval in October 2003. We evaluated survival to discharge during the implantation hospitalization, hospital length of stay, and hospital costs, and compared them with outcomes reported from the REMATCH (RM) trial. RESULTS: All patients in this cohort implanted post-REMATCH (PRM) had class IV heart failure and were similar in age, gender, and nearly all other pre-implantation clinical measures to the RM subjects. Mean hospital costs for PRM patients were 40% lower than for RM patients when measured from implantation to discharge (dollar 128,084 vs dollar 210,187, p < 0.01). PRM patients who survived implantation hospitalization had 48% lower costs than those who did not survive (dollar 114,979 vs dollar 215,456, p < 0.01), a finding similar to the RM experience. PRM patients in this cohort were more likely to survive to discharge compared with RM patients (87.0% vs 67.3%, p = 0.09). Mean hospital length of stay was 25% lower in the PRM group (44 vs 33 days) but did not reach statistical significance (p = 0.50). CONCLUSIONS: Outcomes with use of LVADs as destination therapy have improved in the post-REMATCH era, including significantly lower hospital costs as well as strong trends toward better survival to hospital discharge and shorter average length of stay.

HeartQuest ventricular assist device magnetically levitated centrifugal blood pump.

Improvements in implantable ventricular assist device (VAD) performance will be required to obtain patient outcomes that are comparable with those of heart transplantation. The HeartQuest VAD (WorldHeart, Oakland, CA, U.S.A.) is an advanced device, with full magnetic suspension of the rotor, designed to address specific clinical shortcomings in existing devices and to maximize margins of safety and performance for an implantable assist device. The device dimensions are 35 x 75 mm, with a total weight of 440 g. The system was designed using extensive computer modeling of device function; a total of two iterations of device prototypes were built before building the clinical version. Animal study results have been very promising, with over 30 calf studies completed. Plasma-free hemoglobin levels returned to preoperative levels, and other hematology results were in the normal ranges. Highlights include clean surfaces seen in a 116-day experiment with no anticoagulation after day 43. Feasibility clinical trials are planned to start in 2006.

Low-dose prophylactic intravenous immunoglobulin does not prevent HLA sensitization in left ventricular assist device recipients.

BACKGROUND: The use of left ventricular assist devices is associated with human leukocyte antigen (HLA) allosensitization. We investigated whether prophylactic treatment with low-dose intravenous immunoglobulin (IVIG), analogous to the use of IgG anti-D (anti-Rh) in preventing Rh immunization, can abrogate HLA allosensitization after left ventricular assist device implantation. METHODS: We retrospectively reviewed the data from 84 consecutive heart failure patients who underwent implantation of a left ventricular assist device as a bridge to transplantation. After implantation, panel reactive antibody (PRA) was measured biweekly to assess sensitization (defined by PRA > 10%). Patients who were sensitized before left ventricular assist device implantation were excluded from further analysis (n = 12). Patients who either did not require perioperatively transfusions of cellular blood products or received other immunomodifying regimens were also excluded from further analysis (n = 21). The rest of the patients were divided into two groups based on whether they received IVIG, 10 g daily for 3 days (IVIG group, n = 26; non-IVIG group, n = 25). The decision as to whether patients received IVIG was not randomized but was based on surgeon preference. RESULTS: The sensitization rates (expressed as ratio of sensitized patients to total patients at risk) in the two groups were similar at consecutive time points (2, 4, 6, 8, 12, 20 weeks) after left ventricular assist device implantation. Also, mean PRA at the same time points did not differ between the two groups. Overall, 34.6% (9 of 26) of the IVIG group became sensitized during mechanical support, compared with 32% (8 of 25) of the non-IVIG group (p = 1.0). A PRA of 90% or greater (high-degree sensitization) occurred in 15.3% (4 of 26) of the IVIG group and 12.0% (3 of 25) of the non-IVIG group (p = 0.5). CONCLUSIONS: The use of low-dose prophylactic IVIG after left ventricular assist device implantation affects neither the incidence nor the severity of HLA allosensitization.

Effect of mechanical circulatory support on outcomes after heart transplantation.

BACKGROUND: Mechanical circulatory support (MCS) before heart transplantation was previously associated with worse post-transplant outcomes than when MCS was not required. Given the changes in technology, expertise, patient selection, and timing of subsequent transplantation, we hypothesized that patients who require MCS before heart transplantation have similar outcomes after transplantation as those not requiring pre-transplant MCS. METHODS: We retrospectively reviewed 278 patients who underwent cardiac transplantation from 1993 to 2002. MCS was required in 72 patients (HeartMate LVAS in 66, CardioWest Total Artificial Heart in 6) and was not required in 206 patients. The influence of pre-transplant MCS on post-transplant outcomes was assessed in the 2 groups. RESULTS: Baseline clinical characteristics (age, gender, etiology of heart failure, history of diabetes mellitus, and donor age and gender) were similar in the 2 groups. One-month and 1-year survival after transplantation did not differ between the groups (MCS, 92% and 85%, respectively vs no MCS, 97% and 92%, respectively). Similar proportions of patients were free from rejection (International Society for Heart and Lung Transplantation score >or=3A) at 1 year of follow-up (MCS, 56% vs no MCS, 52%, p = 0.60). No difference was observed between MCS and no MCS patients in other post-transplant events such as hospital stay, intensive care unit stay, extubation time, acute allograft dysfunction, reoperation rates, acute renal dysfunction, acute hepatic dysfunction, infections, arrhythmias, thromboembolic complications, neurologic complications, gastrointestinal complications and the development of cardiac allograft vasculopathy. The incidence of chronic renal insufficiency was actually lower in the MCS Group (15.3% vs 37.9%, p = .001). CONCLUSION: Post-transplant outcomes after pre-transplant use of MCS are similar to those when MCS is not required.