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Endovascular Stenting of a LVAD Outflow Graft Thrombosis

Hubbert, Laila; Forssell, Claes; Baranowski, Jacek; Lindgren, Bo; Holm, Jonas; Ahn, Henrik

doi: 10.1097/MAT.0000000000000371
Case Reports

We report the endovascular stenting of an outflow tract thrombosis in a left ventricular assist device in a patient with relative contraindications to sternotomy and pump exchange. This report highlights the importance of simultaneous prevention of stroke using filter devices in the common carotid arteries.

From the *Department of Cardiology, Department of Medical and Health Sciences, Department of Thoracic and Vascular Surgery, and §Department of Clinical Physiology, Linköping University, Linköping, Sweden.

Submitted for consideration November 2015; accepted for publication in revised form March 2016.

Disclosures: The authors have no conflicts of interest to report.

Correspondence: Laila Hubbert, MD, PhD, Department of Cardiology, University Hospital, SE-581 85 Linkoping, Sweden. Email: laila.hubbert@regionostergotland.se.

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

The use of a left ventricular assist device (LVAD) has grown rapidly. Outcome continues to improve, but feared complications such as thrombosis and embolic events related to treatment with LVAD can occur even with adequate anticoagulation.1 Endovascular stenting in the management of an arteriobronchial fistula from an LVAD outflow graft, outflow cannula obstruction, and pseudoaneurysm has been performed with promising early success rates.2–4 This procedure could be an attractive alternative to resternotomy in high-risk patients. Technical considerations such as avoidance of the distal end of the wire entering the pump house, damaging the rotor and causing pump malfunction, is mandatory. This case report illustrates this treatment option in a patient with an LVAD, with sudden onset of a persistent low-flow alarm warning and clinical signs of heart failure.

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Case Report

A 60 year-old man with hypertrophic cardiomyopathy and 2 years treatment with a HeartMate II (Thoratec Corp. Inc., Pleasanton, CA) was admitted to hospital due to a sustained alarm warning for low pump flow.

Two years previously, in the early postoperative period after pump implantation, profound bleeding problems occurred due to low thrombocyte levels, and several reoperations to stop diffuse bleeding were performed. Coagulation tests showed borderline thrombocyte dysfunction, and the patient had a history of nosebleeds while taking coumadin (international normalized ratio [INR] 2–3) and aspirin (75 mg). Apart from that, there were no further complications, and he was accepted for heart transplantation but chose to wait for family reasons.

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Acute Evaluation

On arriving at the hospital, the pump alarm warned for low flow. He was clinically stable at rest but short of breath on mild exertion. Lactate dehydrogenase (LDH) and bilirubin were normal, and there was no sign of infection. The pump log revealed a flow in the range of 1.5–2.0 L/min, an LVAD pulsatility index ranging from 2.9 to 3.1 with power of 4.2–4.6 Watt, and no power peaks were seen. Transthoracic echocardiography showed a low velocity flow of 0.4 m/s in the inflow cannula, which was regarded as minimal LVAD output. Left ventricular (LV) ejection fraction at rest was not affected, and due to the hypertrophic myocardium, there was no severe dilatation of the LV. The aortic valve was seen to open in every systole.

A computed tomography angiogram (CTA) was performed and showed profound thrombosis in the outflow graft (Figure 1). The Heart Transplant Board did not accept the patient for urgent heart transplantation before pump exchange. Because of the high risk for bleeding during surgery together with renal dysfunction and the patient’s unwillingness to undergo destination therapy, pump exchange was not considered a suitable option.

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Endovascular Procedure

Through double (ultrasound-guided) punctures in the right common femoral artery, 26 French (F) 90 cm introducers (Destination MP-CCV; Terumo, Elkton, MD) were placed and guided to the left and right common carotid artery. An Advantage 0.035″ 260 cm guidewire followed by an AQUA BER 4F 100 cm catheter (Cordis, Tipperary, Ireland) with a 7 mm carotid filter (SpiderFX EV3; Covidien, Tullamore, Ireland) was then placed in the distal common carotid artery on each side.

Through an ultrasound-guided puncture in the left axillary artery, a 12F 45 cm introducer (Flexor Check-Flo Ansel 1 Modification; Cook, Bjaeverskov, Denmark) was placed after preclosure with a Perclose ProGlide suture (Abbott, Diegem, Belgium).

Access to the outflow graft of the LVAD was made using an Advantage 0.035″ 260 cm guidewire with an Aqua Ber 4F 100 cm catheter. The thrombus was very fibrotic and could not be passed with the guidewire. After several attempts, the thrombus was finally penetrated with a 0.014″ guidewire (Approach Hydro ST; Cook, Bloomington, IN) and after dilatation with a 2 mm balloon (Armada 14 XT; Abbot), a 4F 110 cm Glidecath Straight (Terumo, Tokyo, Japan) catheter could be passed through the thrombus. After placing a Rosen curved 0.035″ 260 cm guidewire (Cook, Bjaeverskov, Denmark), inflating a 4 × 40 mm percutaneous transluminal angioplasty (PTA) balloon, and using this as an introducer dilator (balloon swallowing technique), the 12F introducer could be advanced through the thrombus. Through the 12F introducer, a Gore Excluder contralateral leg endoprosthesis 16 × 11.5 mm (PLC161200; Gore, Flagstaff, AZ) was placed and dilated with a 14 × 40 mm PTA balloon (Figure 2). The Gore Excluder leg was chosen because of the very short nose cone and the small access diameter. After retrieving the carotid filters, a large clot was found in the left one (Figure 3).

Immediately after stenting of the outflow graft, the alarm for low flow ceased and pump flow returned to normal for the patient (4.7 L/min). Transoesophageal echocardiography also showed a marked increase in flow in both the inflow and the outflow cannulae (Figure 4). Neurology, laboratory works, CT scan of the brain, and an ultrasonic evaluation of the abdominal arteries showed no sign of embolus. Four days later, a control CTA revealed an outflow graft free from inner lumen thrombosis (Figure 1, right panel).

Anticoagulant treatment before and during stenting was aspirin and intravenous heparin. Afterward, subcutaneous high-dose, low-molecular-weight heparin and aspirin were given while coumadin was reintroduced.

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Discussion

Before the procedure, we were not sure if the stenotic graft was caused by intraluminal thrombosis or a clot between the graft and the bend relief. There were no signs of thrombosis in the pump house because laboratory tests and acoustic signals were normal. Pump exchange was therefore not regarded as being necessary. Stenting of the graft was considered to be both therapeutic and diagnostic, concerning the nature of obstruction of blood flow in the pump house. The result of an immediate return to a normal pump flow after stenting indicated that the pump was working perfectly.

A week after the procedure, the patient experienced a subarachnoid hemorrhage, probably the result of intensified anticoagulation. He underwent surgery and thereafter developed a cerebral infection but recovered without major sequelae. With the history of bleeding complications, mild thrombocyte dysfunction, and then subarachnoid hemorrhage, the patient was discharged with coumadin (INR 2.0–2.5) but no aspirin. After further recovery from mild mental fatigue, he is now considered for heart transplantation.

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Summary

A patient with thrombosis in the outflow graft of an LVAD underwent successful endovascular stenting with simultaneous protection against emboli to the carotid arteries. The endovascular stent approach is a realistic alternative in a patient with LVAD outflow thrombosis where pump exchange is relatively contraindicated due to high risk.

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References

1. Kirklin JK, Naftel DC, Kormos RL, et al: Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) analysis of pump thrombosis in the HeartMate II left ventricular assist device. J Heart Lung Transplant 2014.33: 12–22.
2. Yanagida R, Kass R, Czer L, Khoynezhad A: Endovascular repair of arterio-bronchial fistula of the outflow graft of HeartMate II left ventricular assist device. J Thorac Cardiovasc Surg 2011.142: 710–711.
3. Abraham J, Remick JD, Caulfield T, et al: Left ventricular assist device outflow cannula obstruction treated with percutaneous endovascular stenting. Circ Heart Fail 2015.8: 229–230.
4. Ganapathi AM, Andersen ND, Prastein DJ, et al: Endovascular stent grafting of a left ventricular assist device outflow graft pseudoaneurysm. Circ Heart Fail 2013.6: e16–e18.

left ventricular assist device; stent; thrombosis

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