Avoidance of Outflow Graft Extrinsic Compression in Polytetrafluoroethylene Reinforcements of the Bend Relief Component

A multicenter evaluation of external outflow graft obstruction with a fully magnetically levitated left ventricular assist device

BACKGROUND

The HeartMate 3 (HM 3; Abbott) left ventricular assist device (LVAD) has improved hemocompatibility-related adverse outcomes. In sporadic cases, external compression of the outflow graft causing obstruction (eOGO) can result from substance accumulation between the outflow graft and its bend relief. We sought to evaluate the prevalence, course, and clinical implications of eOGO in an international study.

METHODS

A multicenter retrospective analysis of HM 3 LVADs implanted between November 2014 and April 2021 (n = 2108) was conducted across 17 cardiac centers in 8 countries. We defined eOGO as obstruction >25% in the cross-sectional area in imaging (percutaneous angiography, computed tomography, or intravascular ultrasound). The prevalence and annual incidence were calculated. Serious adverse events and outcomes (death, transplantation, or device exchange) were analyzed for eOGO cases.

RESULTS

Of 2108 patients, 62 were diagnosed with eOGO at a median LVAD support duration of 953 (interquartile range, 600-1267) days. The prevalence of eOGO was 3.0% and the incidence at 1, 2, 3, 4, and 5 years of support was 0.6%, 2.8%, 4.0%, 5.2%, and 9.1%, respectively. Of 62 patients, 9 were observed, 27 underwent surgical revision, 15 underwent percutaneous stent implantation, 8 received a heart transplant, and 2 died before intervention. One patient underwent surgical revision and later stent implantation. The mortality with therapeutic intervention was 9/53 (17.0%).

CONCLUSIONS

Although uncommon, HM 3 LVAD-supported patients might develop eOGO with an increasing incidence after 1 year of support. Although engineering efforts to reduce this complication are under way, clinicians must maintain a focus on early detection and remain vigilant.

The effect of occlusive polytetrafluoroethylene outflow graft protectors in left ventricular assist device recipients

BACKGROUND

The use of polytetrafluoroethylene (PTFE) material as a protective cover for left ventricular assist device (LVAD) outflow grafts (OG) is a common practice. However, it has descriptively been linked to the development of blood flow obstruction (BFO).

METHODS

Patient data from 194 consecutive HVAD (Medtronic Inc; Medtronic, Minneapolis, MN) recipients implanted between March 2006 and January 2021 were retrospectively analyzed. PTFE covers were used in 102 patients. Study outcomes included the incidence of BFO and survival on LVAD support.

RESULTS

Thirty-seven patients (19.1%) developed BFO during the study period. On a multivariable Cox regression analysis, PTFE use was an independent predictor for the development of BFO (HR 2.15, 95% CI 1.03-4.48, p = .04). BFO comprised of 2 types of device malfunction: eleven patients (5.7%) developed outflow graft stenosis (OGS), and 31 patients (16.0%) developed pump thrombosis (PT). There was a significantly higher cumulative incidence of OGS in patients with PTFE cover than in those without (Gray's test, p =.03). However, the observed higher cumulative incidence of PT in PTFE patients was non-significant (Gray's test, p =.06). In a multivariable Cox regression model, the effect of PTFE use on survival was non-significant (HR 0.95, 95% CI 0.60-1.48, p =.81), while the development of BFO was independently associated with increased mortality (HR 3.43, 95% CI 1.94-6.06, p < .0001).

CONCLUSIONS

The use of PTFE OG cover in LVAD patients is associated with an increased cumulative probability of development of BFO, the latter adversely impacting survival and is therefore, harmful.

Right Atrial Compression From Biodebris Associated With Long-Term Left Ventricular Assist Device Support

Biodebris surrounding HVAD (Medtronic) intrapericardial centrifugal-flow left ventricular assist device outflow cannulas is common and appears to accumulate over time. We recently encountered 2 patients on long-term HVAD support with right atrial compression from such biodebris, prompting a review of our institution's HVAD cohort to better understand this phenomenon. (Level of Difficulty: Intermediate.).

Endovascular management of left ventricular assist device outflow graft stenosis

Stenosis of left ventricular assist devices has traditionally required open operative management with device revision or replacement; however, endovascular therapy is emerging as an alternative to open surgery. Limited by the rarity of this approach, consensus is lacking regarding the optimal technique. In this publication, we present a case report of outflow graft stenosis managed with endovascular treatment and discuss technical considerations including preoperative planning, stent selection, and procedural adjuncts.

Incidence, clinical relevance and therapeutic options for outflow graft stenosis in patients with left ventricular assist devices

OBJECTIVES

We reviewed our institutional experience with outflow graft stenosis (OGS) in 3 contemporary left ventricular assist devices (LVAD).

METHODS

Data from 347 consecutive adult recipients of LVAD [Medtronic HVAD (n = 184, 53.0%), Abbott HeartMate II (n = 62, 17.9%) and Abbott HeartMate 3 (n = 101, 29.1%)] implanted between March 2006 and October 2019 were analysed retrospectively. Primary study end points were the incidence of OGS necessitating treatment and survival on LVAD support.

RESULTS

During the study period, 17 patients (4.9%) developed OGS requiring treatment with a probability of 0.6% at 1 year, 1.9% at 2 years, 3.8% at 3 years, 4.7% at 4 years and 5.9% at 5 years of LVAD support. Notably, in 13.8% of patients, a compression-related narrowing of the outflow graft with a probability of 1.5% at 6 months, 1.8% 1 year, 6.0% at 2 years, 12.3% at 3 years, 15.4% at 4 years and 16.6% at 5 years of LVAD support with no difference between devices (P = 0.26) was observed. There was a trend towards increased risk of mortality with OGS (hazard ratio 2.21, 95% confidence interval 0.87-5.51; P = 0.09). OGS preferentially occurred in segments of the outflow graft covered by a protective coating.

CONCLUSIONS

OGS is a rare but potentially lethal complication during LVAD support. Modifications of pump design and implant techniques may be needed because OGS preferentially occurs within covered portions of the outflow graft. Systematic screening may be warranted.

Surgical treatment of outflow graft kinking complicated by external obstruction with a fibrin mass in a patient with LVAD

BACKGROUND

Outflow graft (OG) obstruction is a dangerous complication that may occur for various reasons after left ventricular assist device (LVAD) implantation.

CASE SUMMARY

We describe the case of a 51-year-old patient on LVAD support who developed significant OG kinking and external OG obstruction due to a fibrin mass causing severe stenosis. Both the OG kinking and external obstruction were eliminated via a left lateral thoracotomy.

Left Ventricular Assist Device Outflow Graft Compression: Incidence, Clinical Associations and Potential Etiologies

BACKGROUND

Left ventricular assist devices (LVADs) have revolutionized the treatment of advanced heart failure, but proliferation of device therapy has unmasked potential complications. Reports have emerged of outflow graft narrowing due to extrinsic compression.

METHODS AND RESULTS

The records of patients with LVADs that had been implanted at our institution were reviewed. Those who had postimplantation computed tomography angiographies sufficient to analyze the outflow graft lumen were identified, and the studies were analyzed to characterize the outflow graft lumen. We identified 241 patients; 110 (46%) had suitable computed tomography angiographies. Of those, 15 (14%) had evidence of outflow graft lumen narrowing, all in HeartMate devices and all within the portion covered by the bend relief. Of the 15, 3 underwent invasive examination, all without intraluminal thrombus but, rather, with biodebris between the bend relief and the outflow graft. Patients with HeartWare devices had a wide range of biodebris accumulation surrounding the outflow graft but no cases of lumen narrowing. On multivariable analysis, 1) time from device implant to scan, 2) nonischemic cardiomyopathy and 3) age at implant were significantly associated with higher risk of graft narrowing.

CONCLUSION

Outflow graft narrowing can be seen in a number of patients with HeartMate LVADs within the portion covered by the bend relief. In the limited number of patients who underwent invasive evaluation, the narrowing was found to arise from extrinsic compression rather than intraluminal thrombus. The clinical significance of this requires further investigation.