Mechanical Thrombectomy for Large-Vessel Occlusion after Fontan Procedure in an Adult

Abstract

Objective

Patients with adult congenital heart disease (ACHD) are at increased risk of thromboembolic events. However, case reports describing the use of mechanical thrombectomy (MT) for acute large-vessel occlusion (LVO) in this population remain limited. This case report describes an LVO caused by cardiogenic embolism in an adult patient who underwent the Fontan procedure for tricuspid atresia.

Case Presentation

A 31-year-old woman with a history of an extracardiac Fontan procedure for tricuspid atresia presented with right-sided paralysis and leftward conjugate deviation. CTA revealed occlusion of the left internal carotid artery with a large ischemic penumbra. MT was performed using a direct aspiration first-pass technique, resulting in complete reperfusion. The patient was discharged with mild residual impairment of dexterity in the right upper hand. At 24 years of age, she had previously developed a large vessel occlusion in the M1 segment of the middle cerebral artery, which was successfully treated with MT, leaving only mild deficits. Despite a comprehensive evaluation for an embolic source, no source was identified. She was therefore diagnosed with embolic stroke of undetermined source and was treated with direct oral anticoagulants. Cardiac CT and delayed-enhancement MRI at the current presentation revealed a thrombus in the rudimentary right ventricle that had not been detected by echocardiography. Anticoagulation therapy was initiated, and no recurrence of thromboembolic events was observed.

Conclusion

Although rare, LVO can occur at a young age in patients with ACHD. A thorough understanding of the unique anatomical characteristics of this population is essential for identifying the source of embolism and optimizing management strategies.

Introduction

More than 85% of patients who undergo pediatric cardiac surgery survive into adulthood. However, this population remains at increased risk of thromboembolic complications, including cerebrovascular events, due to their unique circulatory dynamics.¹⁾ The number of patients with adult congenital heart disease (ACHD) has increased as a result of advances in medical care, and this trend is expected to continue.²⁾ Consequently, opportunities for clinicians to manage ACHD-related complications are likely to increase. Despite this, reports describing the use of mechanical thrombectomy (MT) in patients with ACHD remain limited. Herein, this case report describes the effectiveness of MT for large-vessel occlusion (LVO) caused by cardiogenic embolism in an adult patient who underwent Fontan surgery for tricuspid atresia.

Case Presentation

A 31-year-old woman with a history of tricuspid atresia was evaluated. She underwent an atrial-pulmonary connection Fontan procedure at the age of 3 years and 4 months. At the age of 16 years, a second Fontan procedure with an extracardiac conduit connecting the inferior vena cava (IVC) to the pulmonary artery was performed to reduce the risk of atrial arrhythmias, along with a concomitant maze procedure. Her past medical history was otherwise unremarkable. The patient was receiving aspirin (100 mg), losartan potassium (50 mg), and carvedilol (10 mg). No significant family history was noted.

At the age of 24 years, the patient developed an LVO in the M1 segment of the middle cerebral artery (MCA). MT was performed, and successful recanalization was achieved. She was discharged with mild residual weakness of the left upper and lower extremities and facial muscles, with a modified Rankin Scale (mRS) score of 1. Transthoracic echocardiography (TTE) and Holter electrocardiography revealed no significant abnormalities. Cardiac catheterization has subsequently been performed every 5 years since the Fontan procedure, revealing no apparent right-to-left shunt. Further, the patient has no history of valvular atrial fibrillation. Therefore, the patient was diagnosed with embolic stroke of undetermined source (ESUS), and rivaroxaban (15 mg/day) was initiated for secondary prevention. The direct oral anticoagulants (DOACs) were administered as an off-label use for ESUS after providing a detailed explanation to the patient and obtaining informed consent. At the age of 25 years, anticoagulation therapy was switched to edoxaban (30 mg/day) owing to a prolonged prothrombin time-international normalized ratio (PT-INR). No recurrent neurological events were observed during the subsequent 7 years.

At the age of 31 years, the patient was found unconscious at home, presenting with right-sided paralysis and leftward conjugate deviation. She was transferred to the emergency department, with a time from the last known well to hospital arrival of 37 min. The National Institutes of Health Stroke Scale score was 27. Non-contrast head CT revealed a hyperdense MCA sign in the left M1 segment without evident early ischemic changes in the left MCA territory (Fig. 1A and 1B). CT perfusion imaging (Vitrea; Canon Medical Systems, Tochigi, Japan) revealed a large hypoperfused region, with a penumbra volume of 121 mL and a small ischemic core of 13 mL in the left MCA territory; however, no perfusion deficit was observed in the anterior cerebral artery (ACA) territory (Fig. 1C–1H). CTA demonstrated contrast loss from the left internal carotid artery (ICA) to the A1 segment and MCA, prompting the decision to perform MT. As recent edoxaban intake was difficult to confirm and the timing of the last menstrual period was unknown, intravenous recombinant tissue plasminogen activator was not administered. A right femoral artery puncture was performed under local anesthesia, with a door-to-puncture time of 61 min. A 9-Fr balloon guide catheter (Branchor; Asahi Intecc, Aichi, Japan) was advanced into the left ICA. Initial angiography revealed occlusion of the M1 and A1 segments (Fig. 2A). A micro-guidewire (CHIKAI14; Asahi Intecc) and microcatheter (Headway 27; Terumo, Tokyo, Japan) were used to navigate a 5-Fr aspiration catheter (SOFIA Flow; Terumo) to the proximal M1 thrombus (Fig. 2B). A single pass of the direct aspiration first-pass technique resulted in complete reperfusion of the M1 segment; however, no perfusion of the left A1 segment was observed. Subsequent right common carotid artery angiography revealed the absence of collateral flow to the left A2 segment via the anterior communicating artery. Therefore, MT for the left A1 occlusion was performed using the same technique, achieving successful reperfusion of the ACA (Fig. 2C). Final angiography confirmed complete reperfusion with a thrombolysis in cerebral infarction (TICI) grade of 3 (Fig. 2D). The puncture-to-reperfusion times were 23 min for the MCA and 65 min for the ACA. Both retrieved thrombi were dark red, suggesting a red blood cell-dominant thrombus (Fig. 2E).

Fig. 1. (A) Plain CT demonstrated a hyperdense sign in the left MCA (red arrowhead). (B) No ischemic changes were observed at the basal ganglia level. (C) CT perfusion demonstrated a large hypoperfusion area (yellow) and a small ischemic core (red) at the basal ganglia level. (D) CT perfusion at the corona radiata level showed a pattern similar to that observed in (B). (E) rCBV mapping identified a small ischemic core in the left frontal region at the basal ganglia level. (F) rCBV mapping at the corona radiata level demonstrated findings similar to those in (D). (G) Tmax mapping revealed a large hypoperfused area. The red area indicates Tmax exceeding 2.2 s at the basal ganglia level. (H) Tmax mapping at the corona radiata level showed findings similar to those in (G).

MCA, middle cerebral artery; rCBV, relative cerebral blood volume; Tmax, time-to-maximum

Fig. 2. (A) Left ICAG demonstrated absent perfusion in the M1 (red arrowhead) and A1 (yellow arrowhead) segments. (B) ADAPT was performed in the M1 segment using a 5-Fr aspiration catheter (red arrowhead). (C) ADAPT was performed in the A1 segment using a 5-Fr aspiration catheter (yellow arrowhead). (D) Complete reperfusion was achieved in the A1 segment, resulting in a TICI3 reperfusion. (E) The aspirated thrombus was dark red, suggesting an RBC-rich thrombus.

ADAPT, a direct aspiration first-pass technique; ICAG, internal carotid artery angiography; RBC, red blood cell; TICI, thrombolysis in cerebral infarction

Early rehabilitation was initiated following the procedure. Postoperative diffusion-weighted imaging and fluid-attenuated inversion recovery sequences demonstrated hyperintense lesions in the putamen, caudate head, insular cortex, and left postcentral gyrus, corresponding to the ischemic core identified on preoperative CT perfusion imaging. MRA revealed no residual occlusion of the major cerebral arteries (Fig. 3A–3C). Further evaluation for the embolic source was repeated. Cardiac CTA revealed contrast defects extending from the rudimentary right ventricle through a ventricular septal defect (VSD) into the left ventricle (LV). Meanwhile, no significant differences were observed in the left atrium (LA) (Fig. 4A). Cardiac delayed-enhancement MRI revealed a poorly enhanced area consistent with a ventricular thrombus. Investigations for deep venous thrombosis, arrhythmias, and thrombotic disorders yielded no significant findings. Anticoagulation therapy was switched from edoxaban to warfarin to prevent recurrence. The patient was discharged with mild residual impairment of dexterity in the right upper hand (mRS score of 1). She was followed in the outpatient clinic without evidence of recurrent thromboembolic events.

Fig. 3. (A) Postoperative MRA demonstrated restored perfusion in the main cerebral arteries. (B) Postoperative DWI revealed small infarcts in the basal ganglia. (C) Postoperative DWI revealed small infarcts in the centrum semiovale.

DWI, diffusion-weighted imaging

Fig. 4. (A) Cardiac CTA demonstrated contrast defects in the rudimentary RV (red arrowhead), extending into the LV (yellow arrowhead) through a VSD. (B) Hemodynamic diagram illustrating tricuspid valve atresia.⁴⁾ (C) Diagram of the Fontan procedure depicting an extracardiac conduit connecting the IVC to the pulmonary artery.⁴⁾ (B, C) Reprinted by permission from the Royal Children’s Hospital, Melbourne, copyright (2026).

Ao, aorta; Gore-tex, W.L. Gore & Associates, Newark, DE, USA; IVC, inferior vena cava, LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; VSD, ventricular septal defects

Discussion

Tricuspid atresia is typically characterized by right ventricular hypoplasia and is commonly associated with atrial septal defect (ASD) and VSD,³⁾ resulting from complete agenesis of the tricuspid valve. In this condition, systemic venous blood is shunted from the right atrium to the LA through the ASD because direct inflow to the right ventricle is absent. Subsequently, blood flows from the LA to the LV and is supplied to the pulmonary circulation via the VSD or a patent ductus arteriosus (Fig. 4B).^3,4) Consequently, infants with tricuspid atresia develop cyanosis due to right-to-left shunting and require appropriate surgical intervention early in life.

The Fontan procedure, initially performed in 1968, has been widely adopted for the treatment of tricuspid atresia and other forms of ACHD. This procedure diverts systemic venous return directly to the pulmonary arteries, thereby bypassing the absent or nonfunctional tricuspid valve.^3,5) Patients who have undergone the Fontan procedure are at increased risk of thromboembolic events, particularly during adolescence and early adulthood. Skubera et al. reported that ischemic stroke and transient ischemic attacks most commonly occur approximately 14 years (±5.2 years) after the procedure.⁶⁾

In patients who underwent the Fontan procedure, paradoxical cerebral embolism resulting from right-to-left shunting or cardiogenic cerebral embolism may occur, with thrombus formation arising from blind-ended structures such as the pulmonary artery stump or a rudimentary ventricle⁷⁾ (Fig. 4C).⁴⁾ Additionally, a retrospective cohort study by Pundi et al. demonstrated that more than 50% of patients develop atrial arrhythmias 20 years after Fontan surgery,⁸⁾ which may further contribute to the risk of cardioembolic stroke.

In tricuspid atresia, approximately 30% of patients have a subtype associated with transposition of the great arteries³⁾; however, the ascending aorta is usually normal. Nevertheless, abnormal branching vessels arising from the aortic arch are generally not observed in patients with this condition; therefore, the anatomical impact on cerebrovascular disease is considered limited. Regarding the Fontan procedure, the extracardiac conduit technique is currently the most commonly used approach. However, alternative techniques, such as direct connection of the right atrium to the pulmonary artery without an extracardiac conduit, may also be performed in some cases.⁹⁾ In either surgical technique, the branching pattern of the aortic arch itself is not altered; therefore, arterial access can be conducted in the same manner as in individuals with normal anatomy. In contrast, when approaching via the venous system, the Fontan circulation results in anatomical and hemodynamic differences in both the superior and IVC compared with normal anatomy. Therefore, careful consideration of the optimal access route is required.

In the evaluation of embolic sources, TTE is the most commonly used modality; however, its sensitivity for detecting left ventricular thrombus is limited (approximately 33%).¹⁰⁾ In the present case report, the diagnostic sensitivity was expected to be even lower due to the abnormal cardiac anatomy. By contrast, cardiac CTA (CCTA) is considered a useful modality for the detection of intracardiac thrombus¹¹⁾ and is frequently employed in patients with ESUS. Routine use of CCTA may therefore be beneficial in patients who have undergone the Fontan procedure. Delayed enhancement cardiac MRI is another valuable modality for detecting left ventricular thrombus, with a reported sensitivity of 88% and a specificity of 99%.¹²⁾ However, its requirement for advanced imaging techniques and longer acquisition times may limit its accessibility compared with CCTA.

Although DOACs are considered the first-line therapy in non-ACHD populations, no clear consensus exists regarding optimal anticoagulation strategies for adult patients who have undergone the Fontan procedure.¹³⁾ With regard to left ventricular thrombus, the American Heart Association suggests that DOACs may be a reasonable alternative to vitamin K antagonists (VKAs) in patients who have difficulty maintaining the PT-INR within the therapeutic range.¹⁴⁾ Nevertheless, VKAs have been more widely used in patients after the Fontan procedure and remain the conventional choice in this population.¹⁵⁾ Furthermore, as patients who have undergone the Fontan procedure characteristically exhibit elevated central venous pressure and reduced cardiac output, they are at increased risk of long-term renal dysfunction.¹⁶⁾ These pathophysiological considerations suggest that VKAs may represent a more suitable option for long-term anticoagulation therapy.

Conclusion

MT was successfully performed in an adult patient with cardioembolic stroke following the Fontan procedure, resulting in a favorable clinical outcome. Identification of a left ventricular thrombus as the embolic source after the Fontan procedure is rare; however, CCTA and delayed enhancement cardiac MRI were useful for detecting this etiology. These imaging modalities also play an important role in preventing stroke recurrence. As the population of adults with congenital heart disease continues to increase, the establishment of evidence-based guidelines for recurrence prevention and anticoagulation therapy in adult patients with a history of the Fontan procedure who experience ischemic stroke is essential.

Disclosure Statement

The authors declare that they have no conflicts of interest.