ABSTRACT
The Medtronic Autologs System allows real-time clinician review of HeartWare HVAD System logfiles, providing supplemental pump data to aid in patient management. In its first year of availability, Autologs generated a 70% increase in logfile submissions, with 73% of all logfile requests being sent to Autologs. Within a month of its launch, Autologs submissions outnumbered the amount of logfiles submitted for manual review. Following the v1.1 release, there was a 20% increase in logfile submissions, with 77% of all logfile requests being Autologs. With the introduction of v1.2, there was another 35% increase in logfile submissions, with nearly 90% of all logfile requests being Autologs. The widespread adoption and utility of the Autologs System highlights the need for clinician access to real-time data analysis in the field of Mechanical Circulatory Support.
Subject(s)
Heart Failure/surgery , Heart-Assist Devices , Monitoring, Ambulatory/instrumentation , Heart Failure/diagnosis , Heart-Assist Devices/history , History, 21st Century , Humans , Monitoring, Ambulatory/historyABSTRACT
Controller algorithms are an important feature for assessment of ventricular assist device performance. Flow estimation is one algorithm implemented in the HeartWare continuous-flow ventricular assist device pump system. This parameter estimates flow passing through the pump and is calculated using speed, current, and hematocrit. In vitro and in vivo studies were conducted to assess the algorithm accuracy. During in vitro testing, three pumps were tested in four water-glycerol solutions at 37°C with viscosities equivalent to hematocrits of 20, 30, 40, and 50%. By using a linear regression model, a correlation coefficient of >0.94 was observed between measured and estimated flow for all conditions. In vivo studies (n = 9) were conducted in an ovine model where a reference flow probe was placed on the outflow graft and speed was adjusted from 1,800 to 4,000 revolutions per minute. During in vivo experiments, estimated pump flow (mean, minimum, and maximum) was compared with measured pump flow. The best-fit linear regression equation for the data is y = 0.96x + 0.54, r = 0.92. In addition, waveform fidelity was high (r > 0.96) in normal (i.e., nonsuction) cases where flow pulsatility was >2 L/min. The flow estimation algorithm demonstrated strong agreement with measured flow, both when analyzing average waveform magnitude and fidelity.
Subject(s)
Heart-Assist Devices/standards , Pulsatile Flow , Algorithms , Animals , Blood Flow Velocity , Equipment Design , Models, Cardiovascular , SheepABSTRACT
Continuous-flow ventricular assist devices (VADs) are a viable therapy for the treatment of end-stage heart failure, offering support for bridge-to-transplantation and destination therapy. As support duration for VADs continues to rise, patient management and device maintenance will play an increasingly crucial role. The HeartWare Ventricular Assist System has currently been implanted in >4,000 patients worldwide. The HeartWare controller stores approximately 30 days of VAD data including pump rotational speed, power consumption, and estimated VAD flow. Routine assessment of controller log files can serve as a pump performance tool and clinical management aid, assisting the clinician to make accurate and timely diagnoses. Here, we discuss the controller's data collection system as well as present the process for evaluation and reporting of controller log files to clinicians.
Subject(s)
Computers , Heart-Assist Devices , Research Report , Telemedicine/instrumentation , HumansABSTRACT
Improved outcomes and quality of life of heart failure patients have been reported with the use of left ventricular assist devices (LVADs). However, little information exists regarding devices in patients undergoing radiation cancer treatment. Two HeartWare Ventricular Assist Device (HVAD) pumps were repeatedly irradiated with high intensity 18 MV x-rays to a dosage range of 64-75 Gy at a rate of 6 Gy/min from a radiation oncology particle accelerator to determine operational stability. Pump parameter data was collected through a data acquisition system. Second, a computerized tomography (CT) scan was taken of the device, and a treatment planning computer estimated characteristics of dose scattering and attenuation. Results were then compared with actual radiation measurements. The devices exhibited no changes in pump operation during the procedure, though the titanium components of the HVAD markedly attenuate the therapy beam. Computer modeling indicated an 11.8% dose change in the absorbed dosage that was distinctly less than the 84% dose change measured with detectors. Simulated and measured scattering processes were negligible. Computer modeling underestimates pretreatment dose to patients when the device is in the field of radiation. Future x-ray radiation dosimetry and treatment planning in HVAD patients should be carefully managed by radiation oncology specialists.
Subject(s)
Heart-Assist Devices , Neoplasms/radiotherapy , Computer Simulation , Humans , Particle Accelerators , Radiation Dosage , Radiotherapy Planning, Computer-Assisted , Scattering, Radiation , X-RaysABSTRACT
HeartWare continuous flow ventricular assist devices (HVAD) configured as biventricular assist devices maintain diurnal flow variation, lead to end-organ recovery, and provide for a successful bridge-to-heart transplantation in the first successful North American use of continuous flow biventricular assist devices.
Subject(s)
Heart Transplantation/methods , Heart-Assist Devices , Shock, Cardiogenic/diagnosis , Shock, Cardiogenic/surgery , Ventricular Remodeling/physiology , Adult , Critical Illness , Emergency Treatment/methods , Equipment Design , Equipment Safety , Follow-Up Studies , Humans , Male , Risk Assessment , Time Factors , Treatment Outcome , Waiting ListsABSTRACT
The circadian rhythm of varying blood pressure and heart rate is attenuated or absent in patients with severe heart failure. In 28 patients supported by a left ventricular assist device (LVAD) for at least 30 days, a restoration of the circadian rhythm was demonstrated by a consistent nocturnal decrease, and then increase, of the LVAD flow while at a constant LVAD speed. The return of the circadian rhythm has implications for cardiac recovery, and the observation indicates that the continuous-flow LVAD has an intrinsic automatic response to physiologic demands.