Transcarotid Artery Revascularization (TCAR): Reversing Flow to Move Carotid Surgery Forward

Stroke continues to plague this country with nearly 800,000 new cases yearly. The vast majority are ischemic, but more importantly, potentially preventable. Carotid occlusive disease, often silent until it is too late, represents a significant source of emboli in ischemic strokes. Appropriate screening with carotid duplex ultrasonography can identify at risk populations. Screening should be considered in those with a carotid bruit, embolic symptoms, concurrent atherosclerotic disease (coronary artery disease, peripheral artery disease, or aortic aneurysm), and in patients with 2 or more atherosclerotic risk factors (hypertension, hyperlipidemia, smoking history, or family history of stroke). Once identified, instituting best medical therapy for carotid stenosis is paramount for stroke risk reduction, and includes an antiplatelet agent, a statin, and good blood sugar control.

For the large subset of patients that can further benefit from adjunctive revascularization, i.e. symptomatic patients and asymptomatic patients with severe disease, carotid endarterectomy (CEA) is widely considered the gold standard option. Introduced nearly 70 years ago, CEA has a long history of being safe and effective in appropriately selected patients. However, in higher risk patients, it is associated with increased rates of adverse events. High risk characteristics for CEA are well-defined, and typically govern who is eligible for transfemoral carotid angioplasty and stenting (TF-CAS), which was introduced over 20 years ago as a potential alternative for high-risk patients. Despite its availability for over 2 decades, TF-CAS has failed to demonstrate superiority over CEA, and widespread adoption has been tempered by an increased rate of periprocedural stroke.

Transcarotid artery revascularization, or TCAR, is a revolutionary procedure that combines the hallmarks of surgical protection with the minimally invasive approach of carotid angioplasty and stenting. Developed by pioneering vascular surgeons, TCAR’s neuroprotection system became available in the United States in 2012 via clinical trials and was FDA cleared in 2015. TCAR involves direct access to the common carotid artery, percutaneous access to the common femoral vein, and a flow controller connecting the two to establish a pressure gradient, i.e. flow reversal (Fig 1). Direct surgical access to the common carotid artery, obtained through a small incision at the base of the neck, allows for proximal clamp placement, and avoidance of the aortic arch, which is a significant source of emboli during TF-CAS. The other major source of emboli during TF-CAS is the carotid lesion itself. During TF-CAS the lesion is first crossed with a wire and filter, which must be deployed distal to the lesion for neuroprotection. During TCAR flow reversal, a well-tolerated and more effective tool for neuroprotection, is established prior to any manipulation of the lesion. Balloon angioplasty and stenting of the lesion can than occur, with any potential emboli removed from circulation due to the robust flow reversal.

Thus far, the results of TCAR are very impressive. The ROADSTER clinical trial established a remarkable 1.4% rate of periprocedural stroke in high-risk patients. It was the lowest reported periprocedural stroke rate of any prospective multicenter trial involving carotid angioplasty and stenting with neuroprotection. Moreover, this low rate has been consistently reproduced in subsequent trials, and in real world practice. The other benefits of TCAR include the ability to avoid general anesthesia, lower rates of cranial nerve injury, shorter hospital stay, and faster recovery with less pain, when compared to CEA, despite being utilized strictly in higher risk patients. CEA will continue to have a role, particularly in patients with heavily calcified and long segment disease, but it is clear that carotid angioplasty and stenting should now largely be performed via the TCAR procedure (Fig 2).

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Fig. 1 - The TCAR procedure includes direct surgical access to the common carotid artery, percutaneous access to the common femoral vein, and a flow controller to connect the two access site creating flow reversal. Carotid angioplasty and stenting can then be performed via the carotid access with robust neuroprotection.

 

Fig 2. Pre- and post- aggressive angioplasty and stenting done under the robust protection of TCAR; Filter from flow controlled removed demonstrating emboli removed from circulation.

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