It's not only the pump: Assessment of human factors of wearable components and user experience of patients with left ventricular assist devices

Multiobjective Optimization of Rotodynamic Blood Pumps: The Use Case of a Cavopulmonary Assist Device

Comprehensive optimization of rotodynamic blood pumps (RBPs) requires the consideration of three partially conflicting objectives: size, hemocompatibility, and motor efficiency. Optimizing these individual objectives independently, the potential of multiobjective optimizations often remains untapped. This study aimed at the multiobjective optimization of an RBP for cavopulmonary support accounting for all three objectives simultaneously. Hydraulic and electromagnetic design spaces were characterized using computational fluid dynamics and computational electromagnetics, respectively. Design variables included secondary flow gap widths, impeller diameters, and stator heights. The size objective encompassed the RBP widths and heights, the hemocompatibility objective was a weighted composite measure of well-established metrics, and the motor objective was determined by motor losses. Multiobjective optimization was performed through Pareto analysis. 81 designs were considered, and 21 Pareto-optimal designs were identified. The Pareto analysis indicated that hemocompatibility performance could be improved by 72.4% with a concomitant 1.5% reduction in the baseline pump volume. This, however, entailed an increase in motor losses by 0.2 W, while still meeting design requirements, with maximum local temperature rises remaining below 0.4 K. The multiobjective optimization led to a Pareto front, demonstrating the feasibility to improve hemocompatibility at reduced pump volume, however, at the cost of a diminished yet still acceptable motor performance.

The Future of Durable Mechanical Circulatory Support: Emerging Technological Innovations and Considerations to Enable Evolution of the Field

The field of durable mechanical circulatory support (MCS) has undergone an incredible evolution over the past few decades, resulting in significant improvements in longevity and quality of life for patients with advanced heart failure. Despite these successes, substantial opportunities for further improvements remain, including in pump design and ancillary technology, perioperative and postoperative management, and the overall patient experience. Ideally, durable MCS devices would be fully implantable, automatically controlled, and minimize the need for anticoagulation. Reliable and long-term total artificial hearts for biventricular support would be available; and surgical, perioperative, and postoperative management would be informed by the individual patient phenotype along with computational simulations. In this review, we summarize emerging technological innovations in these areas, focusing primarily on innovations in late preclinical or early clinical phases of study. We highlight important considerations that the MCS community of clinicians, engineers, industry partners, and venture capital investors should consider to sustain the evolution of the field.

Addressing the functional needs of left ventricular assist device candidates: Development and feasibility of an occupational therapy pre-operative evaluation

BACKGROUND

Everyday living with a left ventricular assist device (LVAD) is complex, particularly for people with physical or cognitive impairments or limited social supports. There is a need for standardized pre-operative functional evaluations.

OBJECTIVES

Our objectives were to describe a pre-operative occupational therapy (OT) evaluation for LVAD candidates, assess its feasibility in routine care, and characterize functional needs.

METHODS

We retrospectively reviewed electronic medical records of pre-operative OT consultations for LVAD candidates over four years (n = 209). Occupational profile, vision, and sensation were operationalized from documentation narratives. Daily functioning was measured with Activity Measure for Post-Acute Care, grip strength with dynamometer, cognition with Montreal Cognitive Assessment and Allen Cognitive Level Screen-5, and LVAD self-management with a performance-based ordinal scale.

RESULTS

89.5 % of consultations were completed, averaging 61.2 min (n = 187): 79.1 % (148/187) inpatient and 20.9 % (39/187) outpatient. Patients completed 87.7 % (164/187) to 100.0 % (187/187) of evaluation components. 21.9 % (41/187) of candidates lived alone. 6.4 % (12/187) and 7.0 % (13/185) had visual and sensory dysfunction. 57.4 % were independent with daily activities (104/181). 17.7 % (32/181) had impaired grip strength. 69.3 % (124/179) had impaired cognition, 29.7 % (51/172) with impaired functional cognition for everyday activities. 88.4 % (145/164) required physical or cueing assistance while practicing LVAD batteries management. OTs interpreted that 20.9 % (39/187) would likely require 24/7 post-operative support with LVAD self-care.

CONCLUSION

Pre-operative OT evaluations were feasible and emphasized complex functional needs. Assessing LVAD self-care abilities may inform candidacy and facilitate early interventions to optimize functioning. OT should be consulted within interprofessional teams for all LVAD candidates.

Insights into the daily life of ventricular assist device coordinators: Outcome of an international questionnaire

BACKGROUND

As the incidence of heart failure in developed countries is on the rise, mechanical circulatory support (MCS) often remains the only treatment option for patients with end-stage heart failure and is well established worldwide. Even though VAD coordinators play a key role in VAD programs, their responsibilities and daily duties are not clearly defined and characterized. Recently published data from the first 5-year multicenter clinical trial assessing experience with the HeartMate 3 left ventricular system (Abbott, Abbott Park, IL) show an overall survival of 61% at 5 years. When it comes to possible improvements to these systems, it is necessary for developers not only to know the status quo but also to determine and consider the visions and wishes of those individuals who take care of patients, provide education and deal with possible complications. This would be helpful a meaningful effort towards implementing a standard of care.

METHODS

To fill this knowledge gap, we conducted an online survey using the SurveyMonkey tool, addressing representatives of programs implanting VADs worldwide. Representatives answered a standardized block of 14 questions and were asked to provide responses within 3 months.

RESULTS

A total of 91 VAD coordinators from centers of various regions of the world completed the survey. The majority came from European countries. The numbers of patients followed up by the centers ranged from <20 to 390 patients. The majority of VAD coordinators had a nursing background (68%). Seventy-seven percent of the centers operate a 24-h hotline and 3-monthly visits to the outpatient department are most common. Fifty-nine percent of the centers do not use an infection scoring system for driveline wound care. The majority of the centers indicated that an optimized follow-up concept including wound care, medication, and social care is crucial and the key issue for an improved outcome. Smaller components and intensified psychosocial support ranked highest in questions about how to improve quality of life. Surprisingly, the future prospects of telemetric monitoring were not rated high in significance.

CONCLUSIONS

There is a wide variability in the composition and tasks of VAD programs worldwide. Implementing a standard of care and improving psychosocial care as well as equipment is regarded most important to improve outcomes and quality of life. From the point of view of those responsible, the significance of telemetric monitoring seemed overrated.

Human Factors Evaluation of HeartMate 3 Left Ventricular Assist Device Peripherals: An Eye Tracking Supported Simulation Study

BACKGROUND

Despite recent design improvements, human factors issues continue to challenge left ventricular assist device (LVAD) therapy. The aim of this study was to evaluate user experience of former non-HeartMate 3 (HM3) LVAD patients post heart transplantation (HTX) and laypersons (LP) with HM3 LVAD peripherals in simulated everyday and emergency scenarios.

METHODS

This single center cohort study included untrained HTX and LP. Seven scenarios, including battery exchanges (without alarm, advisory alarm, dim light, consolidated bag), change of power supply, driveline dis-/reconnection and controller exchange were simulated. Subjects' gaze behavior was recorded using eye tracking technology. Success rate, pump-off-time, duration to success (DTS), percental fixation duration per areas of interest and post-scenario-survey results were defined as outcome measures.

RESULTS

Thirty subjects completed 210 scenarios, initially solving 82.4% (HTX vs. LP, p = 1.00). Changing power supply revealed highest complexity (DTS = 251 ± 93s, p = 0.76): 26.7% succeeded at first attempt (p = 0.68), 56.7% at second attempt, with significantly more LP failing (p = 0.04), resulting in 10 hazards from driveline disconnections (pump-off-time 2-118s, p = 0.25). Comparison on initial success showed differences in fixation durations for seven areas of interest (p < 0.037). Decreasing DTS during battery exchanges (p < 0.001) indicate high learnability. Exchanging batteries within the bag took longer (median DTS = 75.0 (IQR = 45.0)s, p = 0.09), especially in elderly subjects (r = 0.61, p < 0.001). Subjects with less initial success were more afraid of making mistakes (p = 0.048).

CONCLUSION

This eye tracking based human factors study provided insights into user experiences in handling HM3 peripherals. It highlights unintuitive and hazardous characteristics, providing guidance for future user-centered design of LVAD wearables.