A novel pump, the left atrial assist device (LAAD), is a device specifically for the treatment of heart failure with preserved ejection fraction (HFpEF). The LAAD is a mixed-flow pump that is implanted in the mitral position and delivers blood from the left atrium to the left ventricle. During the development process, we aimed to explore whether device activation in torque control (TC) mode would improve the function of the LAAD. The TC mode causes adjustment of the pump speed automatically during each cardiac cycle in order to maintain a specified torque. In this study, we tested four different TC settings (TC modes 0.9, 1.0, 1.25, and 1.5) using an in vitro mock circulatory loop. Mild, moderate, and severe diastolic heart failure (DHF) conditions, as well as normal heart condition, were simulated with the four TC modes. Also, we evaluated the LAAD in vivo with three calves. The LAAD was implanted at the mitral position with four TC settings (TC modes 0.9, 1.0, 1.1, 1.2). With LAAD support, the in vitro cardiac output and aortic pressure recovered to normal heart levels at TC 1.25 and 1.5 even under severe DHF conditions with little pump regurgitation. The TC mode tested in vivo with three calves, and it also showed favorable result without elevating the left ventricular end-diastolic pressure. These initial in vitro and in vivo results suggest that the TC mode could be potentially effective, and the LAAD could be a treatment option for HFpEF patients.

The MagScrew Total Artificial Heart (TAH) system is the result of a close collaboration among the Cleveland Clinic Foundation, Foster Miller Technologies, Wilson Greatbatch Ltd, and Whalen Biomedical Inc. The system components are the thoracic blood pumping unit with attached compliance chamber and refill port, implantable electronic control unit, implantable battery pack, transcutaneous energy transmission system, external battery pack, and a telemetry system for communication with the electronic control unit. System in vitro tests are underway for system characterization and durability demonstration, whereas in vivo tests were conducted to evaluate system performance and biocompatibility under physiologic conditions. The passively filling pump uses a left master alternate left and right ejection control mode and has a Starling law-like response to venous pressure. The in vitro tests documented excellent hydraulic pump performance with high device output of over 9 l/min at left atrial pressures below 12 mm Hg. Atrial balance was well maintained under all test conditions. The in vivo tests demonstrated good biocompatibility without use of anticoagulant therapy. Experimental durations have ranged between 0 and 92 days. Postexplant evaluation of tissue samples did not reveal any sign of thromboembolic events or tissue damage due to device operation.

The PediPump was implanted in six healthy lambs (mean 25.6 ± 1.4 kg) between the left ventricular apex and the descending aorta to evaluate in vivo performance for up to 30 days. Anticoagulation was achieved by continuous heparin infusion. Three animals were euthanized prematurely, two because of respiratory dysfunction and one because of deteriorating pump performance resulting from thrombus formation inside the pump. Three lambs were electively sacrificed 30 days after implantation; all had stable hemodynamics and minimal hemolysis, as indicated by low plasma free hemoglobin (2.5 ± 3.1 mg/dL). Mean 30-day pump flow was 1.8 ± 0.1 L/min at a pump speed of 12 200 ± 400 rpm. Neither activated clotting time nor activated partial thromboplastin time followed the changes in heparin dose. At necropsy, depositions were observed at the front (n = 1) and rear rotor axial positioning stops (n = 4); improved polishing techniques on the stationary stop surfaces and the addition of a hard-carbon, thin-film coating on the rotating stop of the pumps used for the last two experiments addressed the deposition seen earlier. In conclusion, the PediPump showed excellent hydraulic performance and minimal hemolysis during support for up to 30 days. Depositions observed at the axial positioning stops in earlier experiments were addressed by design and material refinements. We continue to focus on developing effective anticoagulation management in the lamb model as well as on further evaluating and demonstrating pump biocompatibility.

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Purpose: This study analyzed a multicenter cohort of patients who underwent left ventricular assist device (LVAD) implantation to distinguish favorable characteristics that increase the likelihood for cardiac reverse remodeling and myocardial recovery. Methods: This was a multicenter study at 4 LVAD implanting sites in the U.S. Baseline patient characteristics, including demographics, medical history and echocardiographic parameters were reviewed. Echocardiographic parameters of LV structure and function were obtained pre-implant and at 1, 3, 6, and 12 months of LVAD support. Responders to LVAD therapy had echocardiographic evidence of reverse cardiac remodeling and achieved an LVEF ≥ 40% and LV ventricular internal diastolic diameter (LVIDd) ≤ 6.0cm. Univariate and multivariate analyses were performed to determine the odds ratio of achieving responder status. Results: The study retrospectively reviewed 311 chronic HF patients receiving LVAD support. The average patient age was 55.6 § 12.9 years, 17.7% were female, 53% had an ischemic cardiomyopathy, and the average duration of HF was 3.4 § 3.0 years pre-implant. In the cohort, 9.32% of patients achieved responder status. Univariate analysis of baseline characteristics was performed to identify predictors of responder status at final echocardiographic time point. Female sex and age ≤ 65 years had improved odds of myocardial recovery (OR 2.31, 95%CI: 1.0 to 5.4, p=0.05 and 2.26, 95%CI: 1.03 to 4.98, p=0.04). Other significant predictors of cardiac reverse remodeling are presented in the figure. In a multivariate analysis, female sex, age ≤ 65 years and an LVIDd ≤ 7.3cm were each individually associated with a 2-fold increase in the odds of cardiac reverse remodeling.