A Comprehensive Review of Risk Factor, Mechanism, and Management of Left Ventricular Assist Device-Associated Stroke

Perioperative Stroke Following Implantation of Left Ventricular Assist Device: A Retrospective Cohort Study

OBJECTIVES

Stroke is common following left ventricular assist device (LVAD) implantation, although comprehensive data on perioperative strokes in this uncommon population is lacking. The current study aim was to characterize the presentation, features, and outcomes of perioperative cerebrovascular ischemia post-LVAD implantation at the authors' institution.

DESIGN

Single-center retrospective cohort.

SETTING

St. Paul's Hospital, Vancouver, British Columbia, Canada.

PARTICIPANTS

Adult patients who received an LVAD between January 1, 2008, and August 31, 2021, were included, and those who died intraoperatively or underwent a concurrent cardiac surgical procedure were excluded.

INTERVENTIONS

Data on demographics, comorbidities, stroke risk factors and characteristics, management, and outcomes (transplant, explant, death with LVAD in situ) were extracted.

MEASUREMENTS AND MAIN RESULTS

After exclusions, 172 adult patients who underwent LVAD implantation during the study period were included and analyzed. The rate of perioperative stroke was 12.8% (22/172). Of these, 72.7% (16/22) had a stroke occur within 7 days of surgery, and 86.4% (19/22) had a primarily ischemic (v hemorrhagic) event. A total of 68.2% (15/22) were intubated, sedated, or recently extubated at symptom onset, complicating diagnosis. All were managed supportively or palliated without specific stroke intervention. Patients who experienced a perioperative stroke had a significantly lower cumulative incidence of survival to cardiac transplantation and a significantly higher cumulative incidence of dying with their device in situ.

CONCLUSIONS

LVAD patients carry a high risk of perioperative stroke. They experience delayed recognition and diagnosis, limited intervention, and poor outcomes. Frequent neurological assessment and a low threshold for neuroimaging are prudent.

In Vitro and In Silico Characterization of the Aggregation of Thrombi on Textured Ventricular Cannula

The unacceptably high stroke rate associated with HeartMate 3 ventricular assist device (VAD) without signs of adherent pump thrombosis is hypothesized to be the result of the emboli produced by the inflow cannula, that are ingested and ejected from the pump. This in vitro and numerical study aimed to emulate the surface features and supraphysiological shear of a ventricular cannula to provide insight into their effect on thrombogenesis. Human whole blood was perfused at calibrated flow rates in a microfluidic channel to achieve shear rates 1000-7500 s-1, comparable to that experienced on the cannula. The channel contained periodic teeth representative of the rough sintered surface of the HeartMate 3 cannula. The deposition of fluorescently labeled platelets was visualized in real time and analyzed with a custom entity tracking algorithm. Numerical simulations of a multi-constituent thrombosis model were performed to simulate laminar blood flow in the channel. The sustained growth of adherent platelets was observed in all shear conditions ( p <  0.05). However, the greatest deposition was observed at the lower shear rates. The location of deposition with respect to the microfluidic teeth was also found to vary with shear rate. This was confirmed by CFD simulation. The entity tracking algorithm revealed the spatial variation of instances of embolic events. This result suggests that the sintered surface of the ventricular cannula may engender unstable thrombi with a greater likelihood of embolization at supraphysiological shear rates.

The History of Durable Left Ventricular Assist Devices and Comparison of Outcomes: HeartWare, HeartMate II, HeartMate 3, and the Future of Mechanical Circulatory Support

The utilization of left ventricular assist devices (LVADs) in end-stage heart failure has doubled in the past ten years and is bound to continue to increase. Since the first of these devices was approved in 1994, the technology has changed tremendously, and so has the medical and surgical management of these patients. In this review, we discuss the history of LVADs, evaluating survival and complications over time. We also aim to discuss practical aspects of the medical and surgical management of LVAD patients and future directions for outcome improvement in this population.