Faculty Bibliography

Post-explant evaluation of the continuous-flow total artificial heart in preclinical studies can be extremely challenging because of the device's unique architecture. Determining the exact location of tissue regeneration, neointima formation, and thrombus is particularly important. In this report, we describe our first successful experience with visualizing the Cleveland Clinic continuous-flow total artificial heart using a custom-made high-definition miniature camera.

The biocompatibility assessment of the Cleveland Clinic continuous-flow total artificial heart is an important part of the device developmental program. Surgical and postoperative management are key factors in achieving optimal outcomes. However, the presence of vascular anatomical abnormalities in experimental animal models is often unpredictable and may worsen the expected outcomes. We report a technical impediment encountered during total artificial heart implantation complicated by unfavorable bovine anatomy of the ascending aorta and brachiocephalic arterial trunk.

BACKGROUND: Data from 3 institutions revealed an abrupt increase in HeartMate II (Thoratec) pump thrombosis starting in 2011, associated with 48% mortality at 6 months without transplantation or pump exchange. We sought to discover if the increase occurred nationwide in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) data, and if so (1) determine if accelerated risk continued, (2) identify predictors, (3) investigate institutional variability, and (4) assess mortality after pump thrombosis. METHODS: From April 2008 to June 2014, 11,123 HeartMate II devices were implanted at 146 institutions. Machine learning, non-parametric Random Forests for Survival was used to explore risk-adjusted thrombosis based on 87 pre-implant and implant variables, including implant date. RESULTS: A total of 995 pumps thrombosed, with risk peaking within weeks of implant. The risk-adjusted increase in pump thrombosis began in 2010, reached a maximum in 2012, and then plateaued at a level that was 3.3-times higher than pre-2010. Pump exchange, younger age, and larger body mass index were important predictors, and institutional variability was largely explained by implant date, patient profile, and duration of support. The probability of death within 3 months after pump thrombosis was 24%. CONCLUSIONS: Accelerated risk of HeartMate II thrombosis was confirmed by Interagency Registry for Mechanically Assisted Circulatory Support data, with risk subsequently leveling at a risk-adjusted rate higher than observed pre-2010. This elevated thrombosis risk emphasizes the need for improved mechanical circulatory support systems and post-market surveillance of adverse events. Clinicians cognizant of these new data should incorporate them into their and their patients' expectations and understanding of risks relative to those of transplantation and continued medical therapy.

The Cleveland Clinic continuous-flow total artificial heart passively regulates itself in regard to the relative performance of systemic and pulmonary pumps. The system incorporates real-time monitoring to detect any indication of incipient left or right suction as input for automatic controller response. To recognize suction, the external controller compares the waveforms of modulating speed input and power feedback. Deviations in periodic waveforms indicate sudden changes to flow impedance, which are characteristic of suction events as the pump speed is modulating. Incipient suction is indicated within 3 seconds of being detected in the power wave form, allowing timely controller response before mean flow is affected. This article describes the results obtained from subjecting the system to severe hemodynamic manipulation during an acute study in a calf.

BACKGROUND: Data for left ventricular assist devices (LVADs) in patients with noninotrope-dependent heart failure (HF) are limited. OBJECTIVES: The goal of this study was to evaluate HeartMate II (HMII) LVAD support versus optimal medical management (OMM) in ambulatory New York Heart Association functional class IIIB/IV patients meeting indications for LVAD destination therapy but not dependent on intravenous inotropic support. METHODS: This was a prospective, multicenter (N = 41), observational study of 200 patients (97 LVAD, 103 OMM). Entry criteria included >/=1 hospitalization for HF in the last 12 months and 6-min walk distance (6MWD) <300 m. The primary composite endpoint was survival on original therapy with improvement in 6MWD >/=75 m at 12 months. RESULTS: LVAD patients were more severely ill, with more patients classified as Interagency Registry for Mechanically Assisted Circulatory Support profile 4 (65% LVAD vs. 34% OMM; p < 0.001) than 5 to 7. More LVAD patients met the primary endpoint (39% LVAD vs. 21% OMM; odds ratio: 2.4 [95% confidence interval: 1.2 to 4.8]; p = 0.012). On the basis of as-treated analysis, 12-month survival was greater for LVAD versus OMM (80 +/- 4% vs. 63 +/- 5%; p = 0.022) patients. Adverse events were higher in LVAD patients, at 1.89 events/patient-year (EPPY), primarily driven by bleeding (1.22 EPPY), than with OMM, at 0.83 EPPY, primarily driven by worsening HF (0.68 EPPY). Most patients (80% LVAD vs. 62% OMM; p < 0.001) required hospitalizations. Health-related quality of life (HRQol) and depression improved from baseline more significantly with LVADs than with OMM (Delta visual analog scale: 29 +/- 25 vs. 10 +/- 22 [p < 0.001]; Delta Patient Health Questionnaire-9: -5 +/- 7 vs. -1 +/- 5 [p < 0.001]). CONCLUSIONS: Survival with improved functional status was better with HMII LVAD compared with OMM. Despite experiencing more frequent adverse events, LVAD patients improved more in HRQol and depression. The results support HMII use in functionally limited, noninotrope-dependent HF patients with poor HRQoL. (Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device [LVAD] and Medical Management [ROADMAP]; NCT01452802).

BACKGROUND: Left ventricular assist device (LVAD) infections including drivelines, pump pockets, and bacteremia are difficult to manage and conservative treatments may not be effective as the infected foreign material remains. METHODS: We performed a retrospective analysis of all 170 HeartMate II (Thoratec, Pleasanton, CA) implantations as bridge to transplant (BTT) between 2004 and 2012 at our institution. Sixty-one patients (36%) developed a culture positive driveline infection, pump pocket infection, bacteremia, or a combination of these. Twenty-six out of 61 patients with an infection and 49 out of 109 patients without an infection went on to receive a heart transplant. RESULTS: The 1- and 3-year freedom from LVAD infection was 60% and 32%, respectively. While early infection tends to first present as driveline infections, late infections tend to present initially as bacteremia. The 1-year likelihood of receiving a transplant in the patients with an LVAD infection group was 37%, compared with 43% in patients without an infection (p = 0.36). One-year survival to transplantation was 76% in patients with LVAD infection compared with 81% without (p = 0.33). The 1- and 3-year posttransplant survival in patients with a LVAD infection was 96% and 91%, respectively, compared with 92% and 88% in patients without an infection (p = 0.48) . CONCLUSIONS: In this nonmatched cohort of LVAD patients with and without infection, selected patients with controlled LVAD infection have an equal chance of getting transplanted with excellent early and late post-transplant survival.