Kathleen Lockard

Incidence and Patterns of Adverse Event Onset During the First 60 Days After Ventricular Assist Device Implantation

BACKGROUND Although ventricular assist devices (VADs) provide effective treatment for end-stage heart failure, VAD support remains associated with significant risk for adverse events (AEs). To date there has been no detailed assessment of the incidence of a full range of AEs using standardized event definitions. We sought to characterize the frequency and timing of AE onset during the first 60 days of VAD support, a period during which clinical observation suggests the risk of incident AEs is high. METHODS A retrospective analysis was performed utilizing prospectively collected data from a single-site clinical database including 195 patients aged 18 or greater receiving VADs between 1996 and 2006. Adverse events were coded using standardized criteria. Cumulative incidence rates were determined, controlling for competing risks (death, transplantation, recovery-wean). RESULTS During the first 60 days after implantation, the most common AEs were bleeding, infection, and arrhythmias (cumulative incidence rates, 36% to 48%), followed by tamponade, respiratory events, reoperations, and neurologic events (24% to 31%). Other events (eg, hemolysis, renal, hepatic events) were less common (rates <15%). Some events (eg, bleeding, arrhythmias) showed steep onset rates early after implantation. Others (eg, infections, neurologic events) had gradual onsets during the 60-day period. Incidence of most events did not vary by implant era (1996 to 2000 vs 2001 to 2006) or by left ventricular versus biventricular support. CONCLUSIONS Understanding differential temporal patterns of AE onset will allow preventive strategies to be targeted to the time periods when specific AE risks are greatest. The AE incidence rates provide benchmarks against which future studies of VAD-related risks may be compared.

Impact of Renal Function Before Mechanical Circulatory Support on Posttransplant Renal Outcomes

BACKGROUND Renal dysfunction is common before mechanical circulatory support (MCS). Mechanical circulatory support frequently improves renal function, but the impact of pre-MCS renal dysfunction on renal function after cardiac transplantation (CTX) is unknown. METHODS Patients with MCS from January 1995 until April 2008 at a single center were included if their MCS duration was at least 60 days and they underwent successful CTX. Patients were followed for 1 year after CTX. RESULTS A total of 116 patients were included in the study. Mechanical circulatory support was biventricular assist device in 28% and left ventricular assist device in 72% (continuous flow left ventricular assist device, 14%). Mean duration of MCS was 124 days. Patients were grouped according to tertiles of pre-MCS creatinine clearance (CrCl): group 1, CrCl less than 45 mL/min; group 2, CrCl between 45 and 65 mL/min inclusive; and group 3, CrCl more than 65 mL/min. Group 3 had the best renal outcomes both after MCS and 1 year after CTX. Regardless of group, patients who had a CrCl of at least 60 mL/min before CTX had similar 1-year posttransplant CrCl (55 versus 53 versus 56 mL/min for groups 1 through 3, respectively; not significantly different). However, the ability to achieve this level of renal function after MCS was less likely in those with the worst renal function before the initiation of MCS (53% versus 74% versus 90% for groups 1 through 3, respectively; p=0.001). CONCLUSIONS The use of MCS leads to improvements in renal function in patients after MCS. However, the renal outcomes after CTX seem to be more dependent on the level of renal function achieved during MCS than on the level of renal function before MCS.

Early adverse events as predictors of 1-year mortality during mechanical circulatory support

BACKGROUND Ventricular assist devices (VADs) provide effective treatment for end-stage heart failure; however, most patients experience > or =1 major adverse events (AEs) while on VAD support. Although early, non-fatal AEs may increase the risk of later death during VAD support, this relationship has not been established. Therefore, we sought to determine the impact on 1-year mortality of AEs occurring during the first 60 days of VAD support. METHODS A retrospective analysis was performed using prospectively collected data from a single-site database for patients aged > or =18 years receiving left ventricular or biventricular support during 1996 to 2008 and who survived >60 days on VAD support. Fourteen major classes of AEs occurring during this 60-day period were examined. One-year survival rates of patients with and without each major AE were compared. RESULTS The study included 163 patients (80% men; mean age, 49.5 years), of whom 87% were European American, 72% had left ventricular support, and 83% were bridge to transplant. The occurrence of renal failure, respiratory failure, bleeding events, and reoperations during the first 60 days after implantation significantly increased the risk of 1-year mortality. After controlling for gender, age, VAD type, and intention to treat, renal failure was the only major AE significantly associated with later mortality (hazard ratio, 2.96; p = .023). CONCLUSIONS Specific AEs, including renal failure, respiratory and bleeding events, and reoperations, significantly decrease longer-term survival. Renal failure conferred a 3-fold increased risk of 1-year mortality. Peri-operative management should focus on strategies to mitigate risk for renal failure in order to maximize later outcomes.

Obese patients and mechanical circulatory support: weight loss, adverse events, and outcomes.

BACKGROUND Obesity and heart failure are increasingly common, but the outcomes, weight changes, and adverse events of patients with advanced heart failure and obesity on mechanical support is not well described. METHODS We retrospectively reviewed all non-underweight patients with durable mechanical support at a single institution from January 2000 until December 2008 and compared outcomes, weight change, and Interagency Registry for Mechanically Assisted Circulatory Support-defined adverse events between obese and nonobese patients. RESULTS A total of 169 patients were included; 113 (67%) nonobese and 56 (33%) obese. Baseline characteristics, pump types, and implant duration were similar for both populations with the exception of more diabetes (61% vs 26%, p < 0.0001) and hypertension (61% vs 42%, p = 0.019) in the obese. Outcomes on mechanical support at 6 months were not different between groups. There was no significant difference between the nonobese and obese groups in the change in body mass index (-0.3 vs -1.0 mg/m(2), p = 0.29) over the duration of support. Obese patients, as compared with the nonobese, had higher incidence rates of sepsis (64.5% vs 34.7%, respectively, p = 0.006) and reoperation for infectious complications (34.2% vs 13.3%, respectively, p = 0.014). Obese patients also had a higher cumulative incidence of sepsis and reoperation for infection. Two-year posttransplant outcomes were not different in the obese and nonobese. CONCLUSIONS Obese patients have similar outcomes on mechanical support, but at the cost of a higher cumulative incidence of sepsis and reoperations for infection; however, obese patients lose little weight while on mechanical support.

Variability in infection control measures for the percutaneous lead among programs implanting long-term ventricular assist devices in the United States

Ventricular assist devices (VADs) are a surgical treatment for heart failure. These devices may be implanted as a bridge to transplant or as destination therapy. After surgical recovery and education regarding device care, patients are discharged home. Meticulous care of the driveline must be taken to prevent infection and trauma of the site throughout the perioperative event and for the duration of support. Currently a standardized protocol for care of the driveline and exit site does not exist. VAD coordinators from across the country discussed the variability in care at different centers in the United States through a series of conference calls. A survey consisting of 16 questions was developed. The survey included questions on preoperative antibiotic recommendations, driveline placement and exit site suturing, frequency of dressing changes, and showering practices. VAD coordinators shared center-specific dressing protocols and any driveline success stories. This survey was sent to 73 centers; 38 centers (52%) responded. The purpose of the survey was to define current practice in order to move toward a standard of practice or protocol based on expert opinion for VAD driveline care and to assess the need for future studies.

Temporal Leukocyte Numbers and Granulocyte Activation in Pulsatile and Rotary Ventricular Assist Device Patients

Individual ventricular assist device (VAD) design may affect leukocytes and impact immunity. Few studies have presented leukocyte and infection profiles in VAD patients over the course of the implant period. CD11b (MAC-1) expression on granulocytes is an indicator of activation during inflammation, mediating extravasation and the release of reactive oxygen species in tissue. No reported studies have presented MAC-1 expression on circulating granulocytes in VAD patients. Fifty-six patients implanted at a single center with a HeartMate II (HMII; n = 32), HeartWare (HW; n = 12), or Thoratec pneumatic VAD (PVAD; n = 12) between 1999 and 2011 were followed for 120 days of support. The leukocyte profiles and infectious events of all patients were evaluated; additionally, a subset had MAC-1 expression on circulating granulocytes was measured (HMII n = 9; HW n = 7; PVAD n = 4). All groups exhibited a significant peak in leukocyte numbers at postoperative day (POD) 14 while simultaneously experiencing a significant decrease in hematocrit. HMII patients exhibited a 3.2-fold increase in granulocyte MAC-1 expression at POD 14, and the temporal trend over the implant period differed from that experienced by HW patients. Further, HW patients experienced significantly fewer infection events. Alterations in leukocyte profiles and granulocyte activation experienced by VAD patients appear to be device-specific. Elevations in leukocyte activation may be related to an increased risk for infection, although the specific relationship between these phenomena in this patient group is not known.

Left Ventricular Assist Device Malfunctions: It Is More Than Just the Pump

Background: Reports of left ventricular assist device (LVAD) malfunction have focused on pump thrombosis. However, the device consists of the pump, driveline, and peripherals, all of which are potentially subject to failure. Methods: Prospectively collected data were reviewed for all LVAD device malfunctions (DMs) occurring in rotary LVADs implanted at a single center between April 2004 and May 2016. Durable LVADs included 108 Heartmate II (HM II) and 105 HeartWare VAD (HVAD). DM data were categorized according to device type and into categories related to the component that failed: (1) controller, (2) peripheral components, and (3) implantable blood pump or its integral electric driveline. Pump-related events were analyzed as pump-specific (suspected or confirmed thrombosis) or nonpump-specific (driveline failure). DM rates were reported as events per 1000 patient-days, and Cox proportional hazard models were used for time-to-event analyses. Cumulative rates of malfunction were examined for the main components of each type of LVAD. Results: Types of DM included controller failure (30%), battery failure (19%), or patient cable failure (14%), whereas only 13% were because of pump failure. DMs were more common in the HM II device (3.73 per 1000 patient-days versus 3.06 per 1000 patient-days for the HVAD, P<0.01). A higher rate of pump-specific malfunctions was discovered in those implanted with an HM II versus an HVAD (0.55 versus 0.39, respectively; P<0.01) and peripheral malfunctions (2.32 versus 1.78 for the HM II and HVAD, respectively; P<0.01); no difference occurred in the incidence of controller DM between the 2 LVADs. Patients with HVAD were 90% free of a pump-specific malfunction at 3 years compared with 56% for the HM II (log-rank P<0.003). Only 74% of the patients with HM II were free of pump thrombosis at 3 years compared with 90% of the patients with HVAD. Freedom from failure of the integrated driveline was 79% at 3 years for the HM II but 100% for the HVAD (log-rank P<0.02). Conclusions: Device malfunction is much broader than pump failure alone and occurs for different components at different rates based on the type of LVAD.

Bariatric surgery for a patient with a HeartMate II ventricular assist device for destination therapy

A patient with a HeartMate II left ventricular assist device who had a body mass index of 52 needed gastric bypass surgery in order to qualify for a heart transplant. Unlike previous experience in which the surgery was performed at the implant hospital, the gastric bypass surgery in this case was performed at a bariatric center of excellence that was a separate facility from the implant hospital. The artificial heart program of the University of Pittsburgh Medical Center worked with the bariatric center of excellence in scheduling the gastric bypass surgery using a multidisciplinary team approach at 2 hospitals to coordinate safe, high-quality patient care in a unique situation.

Preoperative liver dysfunction influences blood product administration and alterations in circulating haemostatic markers following ventricular assist device implantation

OBJECTIVES Preoperative liver dysfunction may influence haemostasis following ventricular assist device (VAD) implantation. The Model for End-stage Liver Disease (MELD) score was assessed as a predictor of bleeding and levels of haemostatic markers in patients with currently utilized VADs. METHODS Sixty-three patients (31 HeartMate II, 15 HeartWare, 17 Thoratec paracorporeal ventricular assist device) implanted 2001-11 were analysed for preoperative liver dysfunction (MELD) and blood product administration. Of these patients, 21 had additional blood drawn to measure haemostatic marker levels. Cohorts were defined based on high (≥18.0, n = 7) and low (<18.0, n = 14) preoperative MELD scores. RESULTS MELD score was positively correlated with postoperative administration of red blood cell (RBC), platelet, plasma and total blood product units (TBPU) , as well as chest tube drainage and cardiopulmonary bypass time. Age and MELD were preoperative predictors of TBPU by multivariate analysis. The high-MELD cohort had higher administration of TBPU, RBC and platelet units and chest tube drainage postimplant. Similarly, patients who experienced at least one bleeding adverse event were more likely to have had a high preoperative MELD. The high-MELD group exhibited different temporal trends in F1 + 2 levels and platelet counts to postoperative day (POD) 55. D-dimer levels in high-MELD patients became elevated versus those for low-MELD patients on POD 55. CONCLUSIONS Preoperative MELD score predicts postoperative bleeding in contemporary VADs. Preoperative liver dysfunction may also alter postoperative subclinical haemostasis through different temporal trends of thrombin generation and platelet counts, as well as protracted fibrinolysis.

DOES LVAD INFLOW CANNULA POSITION CONTRIBUTE TO THE DEVELOPMENT OF PUMP THROMBOSIS REQUIRING DEVICE EXCHANGE

Pump thrombosis requiring device exchange is a dreaded complication after implantation of a left ventricular assist device (LVAD). Sub-optimal inflow cannula (IC) positioning at the time of implant or changes in IC position due to weight gain or ventricular remodeling may lead to non-laminar flow.