Intracranial and visceral arterial embolization of a cardiac myxoma that was treated with endovascular stent-retriever therapy

Abstract

We report a case of a ruptured left atrial myxoma with multiple synchronous sites of embolization, including the intracranial cerebral (left middle cerebral artery (MCA) and basilar), visceral (renal, superior mesenteric artery (SMA)) and peripheral circulatory beds (aorta and lower extremities). This synchronous embolization resulted in a catastrophic neurologic and systemic event. An intracranial stent retriever was used to restore cerebral circulation in the symptomatic left MCA distribution, which resulted in resolution of the acute neurologic deficits. Endovascular and open surgical interventions were later performed to address the residual cardiac mass and other embolic sites. The patient survived the event with the loss of her right leg below the knee and a transient dialysis requirement. The purpose of this case report is to document the successful utilization of a stent-retriever device in removing an embolized myxoma from the cerebral circulation, to review the unique pathology of this source of embolic stroke and to reiterate the importance of considering embolic and non-thrombotic etiologies of acute ischemic stroke, especially in atypical patient populations and patient presentations.

Background

Current stroke therapy protocols for adult patients include the rapid utilization of intravenous (IV) tissue plasminogen activator (tPA), when needed intra-arterial catheter thrombectomy is also indicated at capable stroke centers. The current generation of endovascular stroke trials such as MR CLEAN¹; and the several positive trials published during 2015^2–5 proved the utility of stent-retriever and mechanical thrombectomy devices for large vessel occlusion. The utility of these techniques has now been proven, both in terms of reperfusion rates and in the more important metric of disability outcomes, as measured by the modified Rankin score. The impetus for the development of these evolving endovascular reperfusion strategies was the historically poor reperfusion rates using IV thrombolytic therapy alone, in the presence of large-vessel occlusions (LVOs).⁶ The high morbidity of these LVOs with poor reperfusion required the development of mechanical adjuncts to IV tPA thrombolysis. These reperfusion tools and techniques are now becoming mature, with high reperfusion rates reported: A recent report documented a reperfusion rate of 97.5%.⁷

This case report will address the utility of the current generation of endovascular tools in the setting of an acute non-thrombotic embolic occlusion. Currently, appropriate atherosclerotic thromboembolic events would be treated first in adults with IV tPA and if needed later, with a mechanical adjunct. In our case, no IV tPA was used. A primary reperfusion strategy utilizing a stent retriever was employed, due to the pathology of the embolism.

Description of event

A 21-year-old woman collapsed and suffered a grand mal seizure while speaking to a prospective employer. EMS was dispatched and she was transported to our nearby endovascular-therapy capable primary stroke center.

She regained consciousness after her seizure subsided, but remained a right-sided hemiplegic and largely aphasic. Her Glasgow coma scale was 10. Her National Institute of Health stroke score (NIHSS) was 12. Blood pressure as measured in the upper extremities was within the normal range (137/99); she had tachycardia at 110 beats per minute, and a tachypnic respiratory rate of 22. The patient’s initial laboratory values were normal, with an exception of a decreased pH of 7.18. The young woman was unable to provide a history. The receiving Emergency Room (ER) team’s primary diagnostic considerations were Todd’s paralysis with a post-ictal state or large vessel occlusion stroke.

Computed tomography (CT) imaging of the head was accomplished, and although subject to significant motion artifact, the images showed no evidence of early infarction with an Alberta Stroke Program Early Computed Tomographic Score (ASPECTS) of 10. The images also failed to show evidence of hemorrhage or of mass. No dense middle cerebral artery (MCA) sign could be identified, in fact the left MCA measured lower in Hounsfield units than right side (Figures 1 and 2). The secondary survey’s physical exam revealed that both lower extremities were cold and pulseless. An urgent ultrasound of the aorta and lower extremities demonstrated no Doppler signal in the distal aorta or proximal iliac arteries. A differential diagnosis of ascending aortic dissection or cardiac embolization was offered to the ER staff. An emergent transesophageal echocardiogram demonstrated a large echogenic mass within the left atrium (Figure 3). The mass was consistent with a typical left atrial myxoma and no dissection was apparent.

Figure 1.

Non-contrast CT image at the level of the suprasellar cistern.

CT: computed tomography

Figure 2.

Coronal reconstruction from the initial non-contrast CT. The proximal left MCA and the right MCA measure 48 HU, the mid left MCA region (arrow) measures 22 HU, suggesting a “hypo-dense MCA sign” of low attenuation embolus.

CT: computed tomography; HU: Hounsfield unit; MCA: middle cerebral artery

Figure 3.

Transesophageal echocardiogram showing the left atrial mass.

Computed tomographic angiogram (CTA) of the chest, abdomen and pelvis was then performed, followed by CTA of the ascending aorta through the skull vertex. Evaluation of the axial source images on the CT monitor showed occlusion of the left MCA. Sagittal reconstructed images demonstrated a “fractured” intra-cardiac mass, as well as aortic and the superior mesenteric artery emboli (Figure 4); left renal occlusive and non-occlusive basilar artery emboli were also diagnosed.

Figure 4.

Sagittal reconstructed CT angiogram showing a “fractured” low attenuation intra-cardiac left atrial mass and embolized material in the aorta and superior mesenteric artery.

CT: computed tomography.

With a documented left MCA embolus and no transfer plan in place, a decision was made to gain groin arterial access for embolectomy of the left MCA occlusion. A number 8 French sheath was placed; the patient was then given 4000 units of IV heparin. We used a H1H catheter for primary access of the left internal carotid artery and made an exchange for the 8 F Flowgate balloon occlusion catheter. A hand-run angiography was done, demonstrating the expected left distal MCA vessel cut-off (Figure 5). One pass was performed with a 4-mm Trevo stent retriever, resulting in the removal of a 5-mm “fatty appearing embolus” with no visible thrombus. Completion of the hand-run angiography then demonstrated reperfusions of the left MCA territory, with Thrombolysis in Cerebral Infarction score (TICI) 3 characteristics (Figure 6).

Figure 5.

Left MCA catheter angiogram injection showing occlusion of the mid to distal left M1.

MCA: middle cerebral artery

Figure 6.

Left MCA angiogram after embolectomy with a stent-retriever device.

MCA: middle cerebral artery

Attention was then turned to the aortic occlusion. Access was also gained via the left common femoral artery: A 10 F sheath was placed in the left common femoral artery (CFA) and the right-sided CFA sheath was upsized to 10 F. A 10 F suction thrombectomy catheter was advanced into the distal aorta, with several passes made on each side. Each pass removed a large quantity of yellow “fatty looking” material, in addition to significant amounts of non-clotted blood. With the removal of the embolic material, the lower extremity perfusion improved; but then with improved flow, recurrent embolization of the remaining material was identified further down the aorta and in the iliac distribution. Transfer of the patient to a quaternary center was arranged, and with the arrival of the air ambulance, the incomplete thrombectomy was stopped and the patient was transported to the accepting facility.

The receiving facility was able to perform Fogarty thrombectomies of the lower extremities, cardiac atrial mass resection and later, another intracranial endovascular stent-retriever was used to facilitate removal of the non-occlusive basilar artery material. The patient recovered without evidence of a fixed neurologic deficit. Her right lower extremity below the knee remained ischemic, ultimately resulting in a below-the-knee amputation. The patient did require temporary dialysis during her hospital admission and her renal function later recovered.

Similar relevant case reports of therapeutic interventions for stroke caused by myxoma were reported in the literature over the last decade. A variety of strategies were used in these reports, including IV tPa, with variable outcomes.^8–12 In our case, the option of mechanical thrombectomy seemed most appropriate from the perspective of the pathophysiology of this event, the available tools, experience and resources. As a result, a successful primary thrombectomy was performed, in our case without IV tPa.

Discussion

Atrial myxoma is the most common cardiac tumor, with an annual incidence of 1 in 2 million per year becoming clinically apparent.¹³ While histologically benign myxomas are potentially dangerous due to embolism, potential cardiac valve occlusion and/or peri-tumoral thrombosis. An embolized myxoma has the potential to cause circulatory restriction in both the systemic and pulmonary circulations. The “at risk circulation(s)” depend on the cardiac chamber affected and with the presence or absence of shunts.

Myxomas are most commonly diagnosed in the adult female between the ages of 30–60 and above. There is a reported female-to-male ratio of 2:1. Myxomas have a predilection for the left atrium, with 75% of the lesions found there; but myxomas have been found in all cardiac chambers.^13,14 Most myxoma cases occur sporadically in the population, although 7% are related to an autosomal dominant familial form. In the autosomal dominant form, the molecular genetic cause is based on the PRKAR1 gene, which is found on the long arm of chromosome 17. This familial form can be part of the Carney complex, which includes cutaneous “spotty pigmentation, cutaneous and cardiac myxomas, endocrinopathies and other cardiac tumors.”^13,15

The classic myxoma clinical triad includes: Obstructive pathology of the cardiac valve(s), which is reported at an incidence of 54–95%, constitutional symptoms such as arthralgias with an autoimmune type of presentation (seen in 34–90%), or embolic phenomena in an acute crisis (reported in 10–45%). The autoimmune constitutional symptoms, when present, have been ascribed to the release of interleukin IL-6 from the myxoma cells; and this may result in elevated reactive markers, such as the sedimentation rate or C-reactive protein.¹⁶ Myxoma diagnosis is said to often be elusive, as the diagnosis is relatively rare and the patient may present with one, two, three or none of the classic clinical diagnostic triad.¹³ Of those presenting with embolic phenomena, there are 75% of these patients having cerebral emboli.

While diagnosis could potentially be suspected by cardiac auscultation and history, the overwhelming majority of these tumors are diagnosed by echocardiography or cross-sectional cardiac imaging, such as by magnetic resonance imaging (MRI) or CT imaging.

Myxoma is a histologically benign tumor, but it can recur; the recurrence of myxomas can be divided into two distinct types: Tumors can recur locally or remotely. Local recurrence rates are low, at 1–3% after surgical resection; however, the local cardiac site recurrence rate in the setting of the Carney complex is notably higher, and may be as high as 25%.¹³ Remote recurrence is due to distal embolization of the tumor, with seeding from an embolic event. These distal embolism recurrences are reported both in the systemic and the central nervous system (CNS) vasculature. The embolized tumor ‘seeds’ can remain viable and grow, which then results in fusiform aneurysms or obstructive intraluminal masses. When recurrence occurs in distal vascular beds with the formation of an aneurysm, that resulting aneurysm may have a mycotic appearance. Embolized intracranial tumor material can also grow and penetrate the vessel wall, then presenting as an intra-axial parenchymal mass.¹³

Myxomas as a cause of stroke

While 75% of embolic events from myxoma involve the CNS, myxoma as a cause of stroke is still rare. Atrial myxoma is estimated as the cause of ischemic stroke in 0.5% of strokes.^17,18 Nonetheless, cerebral myxoma embolization represents a unique challenge for the healthcare team. With the presentation of acute stroke, rapid imaging is now the standard of care and essentially always required. CT angiographic imaging is typically the first-line vascular assessment in the setting of a suspected large vessel occlusion. The findings of myxoma embolism can be detected by this routinely necessary CTA imaging of the head and neck. As a result, the typical imaging work-up of a stroke can reveal the findings to support this rare diagnosis. If a primary cardiac source is on the differential for stroke, then imaging from the level of the atria through the vertex of the skull is required; therefore, imaging through the cardiac chambers, in addition to CTA imaging of the head and neck, would be appropriate in patients who have demographic differences from the typical stroke patient (especially the young) and in patients with signs of multiple territory embolism.

In this experience, the stent retriever allowed rapid reperfusion of the left MCA territory, in <8 minutes from arterial puncture. The rapid reperfusion and the patient’s relatively robust native intracranial collateral vessels are thought to be the reason that long-term neurologic deficit was avoided.

Case reports do exist of successful percutaneous suction catheter-based myxoma embolectomy from coronary vessels.¹⁹ There was also a recent report of a MCA intracranial embolectomy, using a stent-retriever in a child¹²; however, IV-tPA is not currently a recommendation for acute ischemic stroke (AIS) in children. The authors are not aware of any other case reports of a stent-retriever used for a myxoma-related stroke in an adult.

Summary

Cardiac tumor embolization is a rare cause of acute stroke. An acute large vessel occlusion in a patient with atypical demographics should prompt consideration of embolic event(s) being potentially secondary to occult pathology. These occult primary causes of embolic stroke include cardiac tumors, along with dissection and paradoxical emboli from the right-to-left shunts. In order to recognize these unusual causes of stroke, the clinical assessment and physical exam should address a broad differential of possible etiologies, specifically considering the embolic and non-thrombotic possibilities. The acute imaging workup for large vessel occlusions now typically includes CT angiography and the important, but relatively uncommon, diagnoses such as: cardiac mass, pulmonary arterial venous malformation (AVM), atrial septal defects and dissection; which can often be made if imaging is tailored to include the heart and any other symptomatic circulatory beds. In some cases, the additional tailored cardiac and systemic imaging in the setting of AIS may facilitate targeted therapeutic interventions in the brain and elsewhere.

This case describes a catastrophic embolic event in a patient who presented with a neurologic event of seizure, right-sided hemiplegia and aphasia. Myxoma was quickly diagnosed and was treated rapidly with an endovascular technique. The utilization of stent-retriever therapy achieved rapid left MCA territory reperfusion and resulted in a favorable neurologic outcome with a modified Rankin score of 0.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding

The authors received no financial support for the research, authorship and/or publication of this article.