https://orcid.org/0000-0001-7605-4708
Abstract
We report on a 6-year-old girl (18 kg/120 cm) who was diagnosed on day 6 postoperative with an occlusive thrombosis of a right ventricle-to-pulmonary artery conduit in the setting of a Ross procedure that was performed for severe native aortic valve insufficiency secondary to late diagnosis of bacterial endocarditis. We applied the Indigo® aspiration system from Penumbra® (Alameda, USA) to mechanically dissolve and remove the thrombus, restore flow, gradually wean from extracorporeal support, and replace the conduit after 4 days. The patient experiences good surgical outcomes at 3 months of follow-up.
CASE PRESENTATION
A 6-year-old girl (18 kg/120 cm) was referred overseas to our institution for severe native aortic valve insufficiency (AVI) acquired after a late diagnosis of Methicillin-sensitive Staphylococcus Aureus endocarditis. Despite intravenous antibiotics, the patient experienced rapid worsening of the AVI within a week before her referral. She developed refractory congestive heart failure. Pre-operative ultrasound showed grade-4 AVI, vegetations on all aortic cusps, moderate-to-severe left ventricle (LV) dysfunction, and normal pulmonary valve. Brain magnetic resonance imaging (MRI) showed clinically insignificant small cerebral septic emboli. The patient underwent an urgent Ross procedure with the placement of a right ventricle-to-pulmonary artery (RV–PA) 18 mm Contegra VenPro conduit. The cardiopulmonary bypass time was 360 min and the aortic cross-clamp time was 131 min. At the end of the surgery, the patient had LV akinesia and required central veno-arterial extracorporeal membrane oxygenation (ECMO) with full assistance and a trans-mitral LV decompression cannula. On postoperative day 4, small clots in the ECMO circuit were identified despite heparinization, and the circuit was replaced. On postoperative day 6, the right ventricle (RV) was severely dilated despite the support and there was no anterograde conduit flow. Cardiac computed tomography (CT) scan suggested complete conduit thrombosis and head scan showed no active bleeding.
The patient had urgent cardiac catheterization to try to restore the RV–PA flow. Angiography demonstrated complete conduit occlusion (Fig. 1A and B). After a discussion with the surgeon, we opted for thromboaspiration instead of thrombus wire-crossing and balloon dilatation. We advanced a 12-Fr 115-cm-long continuous aspiration thrombectomy (CAT) 12 Indigo catheter from the femoral vein, connected to the Lightning® aspiration tubing and the Penumbra ENGINE®. After managing to position the catheter in the RV proximal outflow, thrombectomy was performed and the system was advanced within the conduit (Fig. 1C and D). Various thrombi were detected by the clot catcher within the canister. Subsequent angiography showed a re-canalized conduit, and a stiff wire was positioned in the right pulmonary artery. We identified smaller sub-occlusive thrombi in the right pulmonary artery (Fig. 1E). We performed another set of aspiration thrombectomies followed by balloon angioplasties (Fig. 1F). Exit angiography showed near-total thrombus removal and flow restoration (Fig. 1G and H). Three hundred millilitres of blood loss was replaced by transfusion and the patient remained haemodynamically stable during the procedure.
Right ventricle angiogram demonstrates total right ventricle-to-pulmonary artery conduit occlusion (A, B). Indigo aspiration system advanced within the conduit after thrombectomy (C, D). Sub-occlusive thrombi in the right pulmonary artery (E) and flow restoration (F). Exit angiography demonstrates near-total thrombus removal and conduit flow restoration (G, H).
Subsequently, the patient was weaned from ECMO as follow-up ultrasounds showed significant improvement in the LV function and normalized RV function. The patency of the femoral vein used for the intervention was confirmed on Doppler ultrasound. On postoperative day 10, the LV function was good enough to remove the ECMO, replace the conduit, and close the chest. Four days later, the total body scan showed no secondary lesion. Five days later, inotropes were stopped, and the patient was switched to non-invasive ventilation. Eight days later, the patient was discharged from the intensive care unit (ICU) with normal LV function, normal aortic valve, and non-stenotic right conduit. One week later, discharge brain MRI was unchanged. Three-month follow-up outcomes are good.
DISCUSSION
Intra-thoracic thrombosis is an uncommon serious complication in children who undergo paediatric cardiac surgeries and the outcomes of thrombosis in this population remain suboptimal [1, 2]. Despite therapeutic anticoagulation for ECMO and adequate activated clotting time monitoring, the patient developed a total RV–PA conduit thrombosis. The patient had several clinical factors associated with increased odds of post-cardiotomy thrombosis [2]. Most importantly, the heart was completely unloaded by the ECMO with no flow to the RV with a valved conduit and this may lead to conduit thrombosis.
The medical antithrombotic treatment was limited [3]. She was already receiving high-dose heparin. Thrombolysis could have been discussed whether locally or systemically, but the risk of bleeding was extremely high, and the odds of success were limited given the size of the thrombus. The only alternative would have been to change the conduit under ECMO with major heart problems and an uncertain outcome.
The Indigo device has been applied recently in adult-sized patients in the management of pulmonary embolism, peripheral arterial and venous thrombus, and coronary vessel occlusions [4]. However, data on the intracardiac use of this device in children with congenital heart disease is limited to 1 case report of a 53-day-old girl with central shunt thrombosis in the setting of pulmonary atresia [5].
When compared to other mechanical thrombectomy systems, the Indigo system is a computer-aided sophisticated device [4, 5]. The built-in microprocessor features a proprietary thrombus removal algorithm that automatically controls the valve in the tubing to provide continuous or intermittent near pure vacuum aspiration (−29 inHg or 98.2 kPa) with intraprocedural audio-visual cues. According to the company, this algorithm helps the operator quickly identify the thrombus location and detect patent flow to reduce potential blood loss. The separators are intended to mobilize the clot and clean the catheter lumen, therefore restoring flow for continuous aspiration. The Penumbra system is not conceived for autotransfusion of aspirated blood and thereby need for blood products should be always considered during the procedure.
In our patient, this large-bore device was effective in establishing the near-complete patency of an occluded conduit in a small child without major blood loss, hemodynamical instability, or pulmonary injury. This approach allowed for stabilizing the patient and bridging him safely to repeat surgery and ECMO removal. The conduit was considered a nidus for small thrombi with a risk of infection and thereby we changed it to optimize the patient's surgical outcomes in the long run.
Indigo CAT catheters vary in diameter from 3.4- to 12-Fr and lengths from 50 to 150 cm. However, Penumbra’s Indigo aspiration system is approved and launched in Europe only with Lightning® 7 and Lightning® 12 which include CAT7 and CAT12 aspiration catheters, respectively. Until this date, the use of the Indigo aspiration system is limited to children with body weight up to which a 7-Fr catheter is applicable.
CONCLUSION
The indigo aspiration system is a viable new tool in the armamentarium of paediatric cardiologists to establish the patency of thrombosed vasculatures in children without increasing the systemic risk of bleeding. This device can be a life-saving option for challenging or refractory thrombosis.
Conflict of interest: none declared.
DATA AVAILABILITY
Data supporting this article will be made available by the authors upon reasonable request.
Reviewer information
European Journal of Cardio-Thoracic Surgery thanks Arun Gopalakrishnan, Walter Knirsch and the other, anonymous reviewer(s) for their contribution to the peer review process of this article.
ETHICAL STATEMENT
The study was approved by the review board of Assistance Publique—Hôpitaux de Paris (MR004: 2023-1023170203). Patient’s parents’ informed consent was obtained for this article.
