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Abstract
Ischemic strokes are seldom caused by free floating thrombi (FFTs) in the carotid artery. Because FFTs are fairly uncommon and their pathophysiology has not yet been clarified, no definite management guidelines have been established. Four consecutive patients with FFTs in the internal and/or common carotid artery are described. These patients were successfully treated by various endovascular treatment methods.
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Introduction
Free floating thrombus (FFT) has been reported as a rare cause of ischemic stroke.1 FFTs usually show significant mobility with intact antegrade flow because parts are stuck to the injured arterial wall. Their instability may make them sources of recurrent artery to artery embolism. The most dreaded complication is detachment, resulting in complete occlusion of the distal cerebral arteries.
Because FFT is fairly uncommon, definite management guidelines have not yet been established. These are considered surgical emergencies, requiring immediate thrombectomy or treatment with anticoagulation therapy.2 Although medical and surgical management have both been successful, neither is clearly superior to the other.1
The recent development of various endovascular devices and techniques has enabled individualized therapy for patients with FFTs. We describe various endovascular techniques that can be successfully applied for the treatment of FFTs in the carotid arteries.
Cases reports
Patient No 1 and 2
A woman in her mid-50s and a man in his early 70s presented with sudden onset of left sided weakness and truncal ataxia, respectively. They were receiving chemotherapy containing cisplatin for lung cancer. An MRI showed acute infarction in the right parietal lobe and the left middle cerebral artery territory, respectively. Contrast enhanced MR angiography (MRA) showed a large, irregular margined filling defect in the mid right common carotid artery (CCA) and distal left CCA, respectively.
Digital subtraction angiography (DSA) revealed an intraluminal thrombus with mobility and 50% stenosis of the arterial lumen (figure 1A). To prevent further embolization or migration, 7 mm×40 mm and 7 mm×50 mm self-expandable stents (Carotid Wallstent; Boston Scientific, Natick, Massachusetts, USA) were deployed in CCA to trap the FFT (figure 1B). We installed distal antiembolic devices (Spider FX; EV3, Plymouth, Minnesota, USA and Filterwire; Boston Scientific Corporation) in the cervical segment of internal carotid artery (ICA) to prevent distal migration.
Right common carotid artery (CCA) lateral angiogram of patient No 1 demonstrates an intraluminal filling defect in the mid portion of the CCA (A). After stent deployment, the final angiogram in the anteroposterior view shows essentially complete resolution of the free floating thrombus (B).
Follow-up duplex ultrasound scan (DUS) confirmed patency of the stented CCA without residual or recurrent stenosis. The patients remain asymptomatic 16 and 14 months later.
Patient No 3
A woman in her mid-50s with rheumatic mitral valve stenosis was admitted for preoperative evaluation. MRA showed a thrombus in the bifurcation of the left CCA. DSA confirmed an extensive thrombus straddling the proximal cervical ICA and also involving the external carotid artery (figure 2A).
Left common carotid artery (CCA) lateral angiogram of patient No 3 shows an extensive saddling thrombus in the proximal cervical internal carotid artery and also involving the external carotid artery (A). A 9 Fr balloon tipped, guiding catheter was placed in the left distal CCA just below the bifurcation, not touching the bottom of the free floating thrombi (FFTs) (B). With vigorous aspiration using a 50 ml syringe, the FFTs were aspirated in the form of multiple, fragmented thrombi (C).
We planned a suction thrombectomy to prevent distal embolism. A 9 Fr balloon tipped, guiding catheter (Tokai Medical Products, Aichi, Japan) was placed in the left distal CCA, not touching the bottom of the FFT (figure 2B). After a distal antiembolic device (Spider FX) was placed, the balloon at the tip of the guiding catheter was inflated to block antegrade flow. Using vigorous aspiration with a 50 ml syringe, FFTs were aspirated as fragmented thrombi (figure 2C). After a control angiogram confirmed the complete disappearance of the intraluminal filling defect, the balloon was deflated. She remains asymptomatic for 8 months.
Patient No 4
A woman in her early 70s with a history of mitral valve replacement was admitted for vertigo. An MRI showed embolic infarction in the right MCA territory. MRA showed long segment occlusion of the right CCA and ICA (figure 3A). DUS showed a large floating lesion with mixed echogenicity loosely attached to the wall of the artery (figure 3B). DSA confirmed a filling defect in the right CCA extending to the petrous segment of the ICA without distal flow. The right hemisphere was filled through exuberant cross filling via the anterior and posterior communicating arteries.
Contrast enhanced MR angiography of patient No 4 demonstrates a long segment occlusion of the right common carotid artery (CCA) and internal carotid artery (ICA) (A). Carotid duplex ultrasound scan reveals a large floating lesion, with mixed echogenicity, which is loosely attached to the wall of the artery from the mid level of the right CCA to the proximal level of the ICA (B). To stabilize the free floating thrombi of the right CCA and ICA, the CCA is trapped with two fibered coils (C).
We initially attempted suction thrombectomy with proximal balloon occlusion but this was unsuccessful due to the large volume of the FFT. We decided against stent implantation because of lesion length and substantial risks of fragmentation and distal embolization. To stabilize the FFTs, we decided to trap the artery via coil embolization using two 4 mm×14 cm fibered coils (Micronester; COOK, Bloomington, Indiana, USA) (figure 3C). Final DSA showed complete trapping of the right ICA without distal embolization. At the 22 month follow-up, the patient has reported no neurologic event.
Discussion
FFTs have a diverse spectrum of pathologies with differing clinical implications. An FFT has been described as an elongated thrombus attached to the arterial wall with circumferential blood flow at its most distal aspect with cyclical motion relating to cardiac cycles. Its etiology is considered multifactorial and it tends to be hypercoagulable in the presence of a cancer.1 As in our patients, cisplatin may increase platelet aggregation and induce direct endovascular damage that may lead to intra-arterial thrombus formation.3 To prevent recurrent stroke in patients with FFT, distal embolism must be inhibited and the intraluminal thrombus must be resolved.
Self-expanding stent placement was effective in the stabilization of FFTs adhering to the injured arterial wall because antegrade flow is not affected by the FFT. Use of a distal antiembolic device is not mandatory because primary placement of self-expanding stents was sufficient. Although thrombi seemed to have a soft consistency, they were sticky enough to be retained by stent meshes due to their elasticity. In our patients, no fragment was captured by the distal antiembolic device.
Suction thrombectomy may be successful in most situations, especially in those in whom the FFT did not contain any immobile portion. These thrombi were successfully removed using a balloon tipped, large bore catheter, although the clot burden was huge. Use of a distal antiembolic device may help prevent distal embolization of the fragmented clots during vigorous aspiration. After achieving flow control of the proximal CCA using the balloon tipped catheter, the device could be safely passed over the FFT.
Arterial trapping may be more destructive but we decided to trap the artery because the involved segment was too vast to stent or suck out and was no longer functional. DUS showed the presence of mobile thrombi with spontaneous echo complexes, which still served as a potential source of distal artery to artery embolism. In these patients, as long as the collateral is sufficient, the arterial segment may be trapped easily using several embolization coils.
In conclusion, these endovascular techniques can be safely and effectively applied to the treatment of FFTs. If each technique alone is deemed not safe or effective, they may be used in combination.
Footnotes
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Competing interests None.
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Patient consent Obtained.
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Provenance and peer review Not commissioned; externally peer reviewed.