Left Ventricular Assist Device Outflow Graft Obstruction: A Complication Specific to Polytetrafluoroethylene Covering. A Word of Caution!

Outflow Graft Tamponade: An Underrecognized Cause of Obstruction

BACKGROUND

Left ventricular assist device (LVAD) outflow graft obstruction can result in severe clinical deterioration. Underlying mechanisms may vary depending on the location. Outflow graft tamponade due to external compression can be under recognized. Management of this complication varies across institutions and a uniform approach has yet to be elucidated.

OBJECTIVES

Report a single center experience with outflow graft tamponade in patients with LVAD with the purpose of developing an optimal algorithm for the diagnosis and treatment of LVAD-related outflow graft tamponade.

METHODS AND RESULTS

Retrospective chart review between July 2011 and July 2020. A total of 351 LVADs were implanted at our center, with outflow graft tamponade identified in 26 patients with LVAD. Fourteen (53.8%) had HeartMate II™, 8 (30.8%) had HeartMate3™ and 4 (15.4%) had HeartWare™. Individuals presented with heart failure symptoms, an audible precordial murmur and LVAD alarms after a median duration of 862 days of support (IQR 327 - 1455). Of the 26 patients, 15 (57.7%) underwent mini thoracotomy with outflow graft relief, 4 had percutaneous balloon dilatation and stenting, 2 were bridged directly to transplant and 1 had a pump exchange. No intervention was made on the remaining due to mild symptoms (n = 4).

CONCLUSIONS

Conclusions: Outflow graft tamponade is a form outflow graft obstruction with a variable presentation that can result in significant hemodynamic compromise. It is amenable to both surgical and percutaneous interventions that restore LVAD function.

Extrinsic Outflow Graft Obstruction of the HeartMate 3 LVAD: A State-of-the-Art Review

While notable improvements in survival, incidence of hemocompatibility-related adverse events, hospitalizations and cost have been demonstrated with the only commercially available durable left ventricular assist device, a category of pump malfunctions characterized by outflow graft obstruction has been noted with broader use and clinical follow up of recipients of this technology. Of particular concern, is the accumulation of acellular biodebris between the outflow graft and bend relief covering the outflow graft at its origin with the pump (which we term extrinsic outflow graft obstruction at the bend relief, or EOGO-BR). This process tends to be insidious, occurs late in the postoperative course, can be challenging to diagnose, and can result in significant morbidity and mortality. Herein we provide a review of this complication and outline diagnostic, treatment and preventive strategies.

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.

Acute Left Ventricular Assist Device Failure From Outflow Graft Dissection Flap Successfully Treated With Stent Placement

Outflow graft obstruction (OGO) is a potentially fatal complication of left ventricular assist device (LVAD) implantation. Common causes include graft kinking, luminal stenosis, and graft thrombosis. We describe a case of a 51-year-old female who presented with acute LVAD failure and cardiogenic shock. Initial imaging revealed OGO without luminal stenosis following which she was she was empirically treated for graft thrombosis with anticoagulation and catheter-based thrombolytic therapy with no success. Further imaging in the catheterization laboratory revealed a potential neointimal flap dissection acting as a one-way valve. A stent was successfully placed across the outflow graft with immediate resolution of cardiogenic shock. The case emphasizes the importance of including neointimal flap as a differential for OGO in acute LVAD failure, especially in cases where thrombolytic therapy fails to correct hemodynamic compromise.

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.

Extrinsic outflow graft flow obstruction in patients with HeartMate3 LVAD

Blood flow obstruction at the level of the outflow graft is a rare but severe complication of LVAD support. We present a series of five patients supported with HeartMate3 LVAD (Abbott Labs, Chicago, IL) that developed an outflow graft obstruction after 607-1250 days of support, during prolonged antithrombotic therapy. Three patients presented with severe symptoms of heart failure, were treated with endovascular stenting and experienced full recovery. Preoperative computed tomography angiography and intraoperative angiography together with intravascular ultrasound provided diagnosis and guided treatment. In two patients, outflow obstruction was an occasional finding at imaging without heart failure symptoms and a "watchful waiting" approach was adopted: delayed treatment in one of them was futile. This late adverse event is peculiar for its pathophysiology and not yet discussed among the mechanical circulatory support community.

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.

Diagnostic and surgical management of HeartMate 3 outflow graft obstruction due to two different mechanisms

Outflow graft obstruction is a potentially catastrophic complication of left ventricular assist devices that may occur secondary to different mechanisms. Two cases of Heartmate 3 outflow graft obstruction associated with two different pathophysiological mechanisms are presented. The first one was a 70-year-old man who developed outflow graft obstruction secondary to kinking. The second case was a 72-year-old man who presented with signs and symptoms of heart failure due to outflow graft extrinsic obstruction. Both cases were diagnosed with 3D-CT scan and successfully surgically treated.

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.

Transaxillary Stenting of LVAD Outflow Graft Obstruction

An 82-year-old man with a HeartMate II left ventricular assist device presented with low-flow alarms and cardiogenic shock secondary to left ventricular assist device outflow graft obstruction. Given high risk for redo sternotomy, the heart team decided on percutaneous intervention with peripheral stents, a procedure that is currently limited to case reports. (Level of Difficulty: Advanced.)

Survival outcomes of stenting outflow graft stenosis in continuous-flow left ventricular assist devices: a systematic review

Stenosis in the continuous-flow left ventricular assist device (CF-LVAD) outflow graft is caused by various factors. We discuss indications for percutaneous intervention of outflow graft complications and evaluate the use of this treatment in re-establishing adequate CF-LVAD flow. An electronic search was performed to identify all studies in the English literature reporting CF-LVAD outflow graft stenting. Twenty-one studies consisting of 26 patients were included. Patient-level data were extracted for statistical analysis. Median patient age was 59 years [45.8-67.0] and 65.4% (17/26) were male. 58.3% (14/24) of patients had HeartWare HVAD, 37.5% (9/24) had HeartMate II LVAD, and 4.2% (1/24) had HeartMate III LVAS. Median time from device placement to outflow graft stenting was 24.0 months [7.8-30.4]. 76.9% of patients (20/26) presented with heart failure. Complications of the CF-LVAD outflow graft included thrombosis in nine patients (34.6%), stenosis in nine patients (34.6%), kinking in three patients (11.5%), pseudoaneurysm in one patient (3.8%), external graft compression in one patient (3.8%), and bronchial-arterial fistula in one patient (3.6%). Immediate flow improvement occurred in 23/26 patients (88.5%), with the remaining 11.5% (3/26) requiring additional procedures. Pre- and post-intervention flows were 2.9 L/min [2.0-3.5] and 4.7 L/min [4.1-4.8] respectively (p = 0.01). Of patients, 96.2% (25/26) were discharged with a median time to discharge of 4 days [3.0-5.0]. The 30-day mortality was 6.7% (1/15). Overall mortality during the median follow-up of 90 days was 9.5% (2/21). Outflow graft stenting appears to effectively alleviate CF-LVAD outflow graft obstruction and is associated with low overall mortality.

Use of a Minimally Invasive Approach to Correct Diffuse External Compression of the Left Ventricular Assist Device Outflow Graft

Left ventricular assist devices (LVADs) implanted into patients with heart failure sometimes develop insufficient forward flow due to malfunction of the outflow graft. One increasingly seen source of outflow graft malfunction is the development of external compression of the outflow graft (ECOG) due to the accumulation of material between the flexible outflow graft and the relatively rigid overlying Gore-Tex tubular graft. When there is segmental ECOG, a percutaneous approach with outflow graft stent placement is the treatment of choice. However, we have encountered cases with diffuse ECOG for which surgery appeared to be a superior choice. We, therefore, developed a minimally invasive surgical approach in which a mini-thoracotomy, rather than redo-sternotomy, is combined with unroofing of the Gore-Tex graft and subsequent evacuation of the organized hematoma. We describe this technique in two patients with diffuse ECOG in whom we found the method to be simple, relatively rapid, and very effective.

Ventricular assist devices implantation: surgical assessment and technical strategies

Along with the worldwide increase in continuous left ventricular assist device (LVAD) strategy adoption, more and more patients with demanding anatomical and clinical features are currently referred to heart failure (HF) departments for treatment. Thus surgeons have to deal, technically, with re-entry due to previous cardiac surgery procedures, porcelain aorta, peripheral vascular arterial disease, concomitant valvular or septal disease, biventricular failure. New surgical techniques and surgical tools have been developed to offer acceptable postoperative outcomes to all mechanical circulatory support recipients. Several less invasive and/or thoracotomic approaches for surgery combined with various LVAD inflow and outflow graft alternative anastomotic sites for system placement have been reported and described to solve complex clinical scenarios. Surgical techniques have been upgraded with further technical tips to preserve the native anatomy in case of re-entry for heart transplantation, myocardial recovery or device explant. The current continuous-flow miniaturized and intrapericardial devices provide versatility and technical advantages. However, the surgical planning requires a careful multidisciplinary evaluation which must be driven by a dedicated and well-trained Heart Failure team. Biventricular assist device (BVAD) implantation by adoption of the newer radial pumps might be a challenge. However, the results are encouraging thus remaining a valid option. This paper reviews and summarizes LVAD preoperative assessment and current surgical techniques for implantation.

Left Ventricular Assist Device Outflow Graft Obstruction: A Case Series

Dysfunction of different components within continuous-flow (CF) left ventricular assist device (LVAD) systems may cause adverse cardiovascular and end-organ sequelae. Outflow graft obstruction is a recognized type of LVAD component dysfunction. Ten patients were admitted and treated for LVAD outflow graft obstruction. Two of these patients subsequently developed recurrent outflow graft obstruction requiring reintervention; however, each reoccurrence was at a different site than the original obstruction. Thus, a total of 12 cases of obstruction were analyzed. The most common reasons for hospital admission were low flow LVAD alarms or decompensated heart failure. Presentation with outflow graft obstruction occurred an average of 3.0 years after LVAD implantation. Patients underwent echocardiographic evaluation at the time of admission. Left ventricular assist device component dysfunction was suspected based on echocardiographic findings, and follow-up contrast studies were used to establish the specific diagnosis of outflow graft stenosis. The majority of stenotic lesions (10/12) were treated percutaneously with balloon angioplasty and stenting with balloon-expandable endovascular prostheses. Postintervention, all patients had significant improvement in LVAD flow rates.

Percutaneous treatment of left ventricular assist device outflow graft obstruction

Owing to the growing population with end stage heart failure, the use of left ventricular assist devices (LVADs) have become more widely accepted. Although survival has improved with newer generation LVADs, multiple complications including pump failure due to outflow graft obstruction have become more clinically relevant. Patients with this complication will present with heart failure symptoms due to inadequate unloading of the left ventricle by LVAD. This rare complication often requires open surgical repair in an already high-risk patient population. Alternative means to relieve the obstruction via percutaneous intervention has been described in rare cases. We present two unique cases of LVAD outflow graft obstruction which were percutaneously treated successfully. This article illustrates a potential treatment strategy for outflow graft obstruction with stenting as an alternative to open-heart surgery.

Left Ventricular Assist Device-Related Complications

Left ventricular assist device (LVAD) has emerged as a safe, durable, and revolutionary therapy for end-stage heart failure patients. Despite the appearance of newer-generation devices that have improved patient outcomes, the burden of adverse events remains significant. Although the survival rate for patients with LVAD is appreciated to be 81% at 1 year and 70% at 2 years, the incidence of adverse events is also high. Over time, both early and late postimplant complications have diminished in terms of prevalence and impact; however, complications, such as infections, bleeding, right heart failure, pump thrombosis, aortic insufficiency, or stroke, continue to represent a challenge for the practitioner. Therefore, the aim of this review is to highlight the most recent data regarding the current use of LVAD in the treatment of end-stage heart failure, with a specific focus on LVAD-related complications, in order to improve device-related outcomes. It will also revise how to mitigate the risk and how to approach specific adverse events. Withal, understanding the predisposing risk factors associated with postimplant complications, early recognition and appropriate treatment help to significantly improve the prognosis for patients with end-stage heart failure.

External compression due to seroma of ventricular assist device outflow graft

A 45-year-old woman with repaired complex congenital heart disease, who underwent placement of Jarvik 2000, a ventricular assist device (VAD) for 4 years, experienced abdominal pain due to outflow graft compression caused by seroma formation between the outflow graft and ringed Gore-Tex graft. We exchanged the pump of Jarvik 2000 and punched several small holes in the new ringed Gore-Tex graft. Seroma formation between the two grafts should be considered as a cause of outflow graft obstruction in patients with the long-term support of VAD, and additional surgical interventions to the ringed Gore-Tex graft may prevent this complication.

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.

Percutaneous Management of Outflow Graft Obstruction in Patients With Continuous Flow Left Ventricular Assist Devices

Outflow graft obstruction (OGO) has been reported as a cause of left ventricular assist device dysfunction. The incidence, diagnosis, and treatment of OGO remains poorly understood. We present our experience with the diagnosis and management of OGO in the cardiac catheterization laboratory. (Level of Difficulty: Advanced.).

A Rare Complication of HVAD Outflow Thrombosis and the Importance of HVAD Waveform Analysis

We present a case of a 64-year-old female who was supported with an HVAD as bridge-to-transplant (BTT) who presented with a gastrointestinal (GI) bleeding and underwent esophagogastroduodenoscopy (EGD) and colonoscopy. Her waveforms changed abruptly following the procedure, and she decompensated. With various imaging modalities and hemodynamic monitoring, we felt that she had thrombus in her outflow graft, which improved following systemic heparinization. She was listed for cardiac transplantation and remained hospitalized. At the time of surgery, her outflow graft was noted to be compressed externally and pathology was consistent with platelet-fibrin thrombus deposition.

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.