Catheter-based thrombectomy for pulmonary artery thrombosis is rapidly expanding and widely used. Reference Konstantinides, Meyer and Bueno1 Nonetheless, there exists a paucity of literature describing its use in surgically repaired CHD, specifically those with non-native pulmonary artery material. While thrombotic occlusion is a well-known risk within this population, Reference Jensen, Idorn and Thomsen2 complex CHD anatomy, often sub-acute nature of thrombosis, and presence of non-native material present a challenge when considering optimal catheter-based therapy. While the use of mechanical thrombectomy has been described in various CHD patients, Reference Fleming, Khan, Janssen and Doyle3–Reference Qureshi, Petit, Crystal, Liou, Khan and Justino6 success has been varied. We describe a case of a surgically repaired CHD patient with complete thrombotic occlusion of her right pulmonary artery interposition graft, successfully managed with a novel mechanical thrombectomy device combined with stenting, catheter-directed thrombolysis, and systemic anticoagulation.
Case
A 19-year-old female with heterotaxy syndrome, unbalanced atrioventricular septal defect, double outlet right ventricle, L-malposed great arteries, interrupted inferior vena cava, and single left-sided superior vena cava previously underwent single ventricle palliation culminating in a Fontan operation. Due to the formation of arteriovenous malformations, she underwent Fontan takedown and biventricular repair at 5 years old with a left ventricle-to-aorta tunnel, left superior vena cava connection to right atrium, and right ventricle-to-pulmonary artery conduit with subsequent right pulmonary artery interposition graft using a 16 mm stretch Gore-Tex graft (W. L. Gore & Associates, Flagstaff, AZ) in the Lecompte position. Following two months of intermittent haemoptysis and two days of acute right-sided pleuritic chest pain, computed tomography demonstrated complete right pulmonary artery occlusion. Upper and lower extremity ultrasounds did not show venous thrombosis. A heparin infusion was initiated, and she was referred for cardiac catheterisation.
A 9-French Uniblocker bronchial blocker (Fuji Systems, Tokyo, Japan) was placed in the right mainstem bronchus to prepare for potential reperfusion injury and pulmonary haemorrhage following right pulmonary artery recanalisation. Cardiac catheterisation was approached via left internal jugular vein and femoral artery. The right ventricular systolic pressure was 70% of systemic blood pressure. Angiography confirmed complete right pulmonary artery occlusion (Fig 1A). To accommodate a 12-French Penumbra Indigo Lightning Aspiration System (Penumbra, Alameda, CA), a 12-French Flexor (Cook Medical, Bloomington, IN) sheath was advanced into the MPA. The occluded graft was successfully cannulated with the stiff end of a 0.014” Grand Slam wire (Asahi USA, Irvine, CA) through a Penumbra Lantern microcatheter, coaxially through a glide catheter. Angiography further demonstrated extensive clot burden (Fig 1B).
Figure 1. Cardiac catheterisation. A : Complete interposition graft occlusion. B : Extensive interposition graft thrombosis. C : Interposition graft following mechanical thombectomy. D : Interposition graft following stent implantation and thrombolysis.
The 12-French Penumbra Indigo Lightning system was advanced over a 5-French Penumbra Select Catheter and 0.035” stiff wire into the distal right pulmonary artery. Intermittent aspiration was performed during cycles of retracting and re-advancing into thrombus, readjusting position based on feedback from the Lightning Intelligent Aspiration system. Repeat angiography demonstrated patent, long-segment graft narrowing (Fig 1C), which was an important nidus for thrombosis. A large quantity of thrombus was collected, combining with blood loss to equal 300cc.
Following recanalisation, three telescoping 36 mm long IntraStent Mega LD stents (Medtronic, Minneapolis, MN), each mounted on 16 mm balloons, were implanted throughout the graft’s length. Due to residual thrombus, catheter-directed thrombolysis was performed with 10mg of tissue plasminogen activator. A final angiogram confirmed graft patency and improved overall clot burden (Fig 1D).
There was no bradycardia, hypotension, renal injury, pulmonary haemorrhage, or need for blood transfusion. The patient’s haematocrit only declined from a baseline of 36.5% to 34.6% post-procedure. Systemic heparin was continued post-catheterisation and transitioned to oral warfarin. A computed tomography the day following catheterisation showed stable graft patency with a residual thrombus immediately distal and proximal to the stented region. Follow-up computed tomography at 2 and 4 months demonstrated near complete resolution of thrombi.
Discussion
Catheter-based intervention for pulmonary embolism within the adult population has been well-described. However, the challenges of device safety and efficacy for the heterogeneous anatomy, various pathophysiologic profiles of thrombotic disease, and post-surgical states of the CHD population remain. Our case represents several related challenges: non-native interposition graft within complex anatomy, post-surgical graft compression, and likely combination of acute and subacute thrombus.
The majority of published experience with mechanical catheter-based thrombectomy in CHD describes the use of a rheolytic system. Reference Fleming, Khan, Janssen and Doyle3,Reference Qureshi, Petit, Crystal, Liou, Khan and Justino6,Reference Kokov, Korostelev and Grinko7 This uses a jet of high-pressure saline, creating a low-pressure area surrounding the jet through which thrombus is aspirated. Risks include haemolysis, kidney injury, blood loss, pulmonary haemorrhage, and bradyarrhythmia, for which it carries a black box warning for use in pulmonary arteries. Reference Giri, Sista and Weinberg8 The Penumbra Indigo Lightning Aspiration System (Fig 2) is a novel suction thrombectomy device which utilises dual pressure sensors to monitor blood flow while engaging and directly aspirating thrombus. Reference Sista, Horowitz and Tapson9 The “Lightning” system automatically controls a valve that toggles between continuous suction when engaged with thrombus and intermittent suction in free-flowing blood, providing alerts when thrombus is no longer detected. This feature attenuates blood loss, which is critical to younger patients. The Indigo system adds a manually controlled mechanical thrombus “separator” that facilitates clearing of thrombus from the catheter tip, but does provide a risk of clot embolisation as presumably not all thrombus will be extracted and could result in potential hemodynamic ramifications. Importantly, the wide range of catheter sizes (3.4-French to 12-French) with flexible trackability facilitates use in a wider range of complex anatomies and the angled tip facilitates torque.
Figure 2. Mechanical thrombectomy system. A : The Penumbra Indigo Lightning Aspiration System with clot detection indicator. B : Angled catheter tip.
In previous descriptions of catheter-based thrombectomy in CHD patients, one of the main challenges to short and long-term outcomes is re-thrombosis. Reference Hirono, Ibuki and Tomita4–Reference Qureshi, Petit, Crystal, Liou, Khan and Justino6 Mechanical thrombectomy has been combined with balloon angioplasty and/or vascular stenting to attenuate this risk. Reference Fleming, Khan, Janssen and Doyle3,Reference Qureshi, Petit, Crystal, Liou, Khan and Justino6 Catheter-directed thrombolysis and systemic anticoagulation can also be considered as adjunct treatments, Reference Qureshi, Petit, Crystal, Liou, Khan and Justino6,Reference Hubara, Borik, Kenet, Mishaly and Vardi10 which proved to be of benefit in our case.
Conclusion
Patients with pulmonary artery thrombosis in surgically altered anatomy and non-native pulmonary artery tissue present a particular challenge. This case demonstrates the successful use of the Penumbra Indigo suction thrombectomy device in a CHD patient with complete thrombotic occlusion of a pulmonary artery interposition graft, an application which has not been reported to our knowledge. This aspiration system allowed for efficient tracking across complex anatomy and controlled recanalisation of the occluded graft through a novel thrombus detection system. Adjunctive stenting, catheter-directed thrombolysis, and systemic anticoagulation were important to the success of this case.
Financial support
This research received no specific grant from any funding agency, commercial or not-for-profit sectors.
Conflicts of Interest
None.
