What’s the diagnosis?
- Patients with a chronically occluded internal carotid artery have an ↑ risk of ischemic events in the ipsilateral hemisphere, about 5% per year.
- In the setting of an occluded internal carotid artery, patients typically depend on collateral circulation to prevent stroke, or infarction in the brain that would have normally been fed by the occluded carotid artery. To augment their collateral circulation, these patients are typically chronically hypertensive.
- Preoperative testing includes imaging studies that document complete occlusion of the internal carotid artery, such as CT angiography. Perfusion imaging is useful to document ipsilateral hemispheric hypoperfusion.
- A complete diagnostic angiogram should be performed to determine whether or not there is any collateral flow to the ipsilateral internal carotid artery distal to the occlusion. For example, in this case the ipsilateral external carotid artery → ophthalmic artery → retrograde filling of the ophthalmic segment of the internal carotid artery. This endoluminal flow in the internal carotid artery distal to the occlusion site implies lumen patency and documents a potential target landing zone to reach if revascularization is going to be attempted.
What's your treatment plan?
In this case, because the patient showed significant clinical worsening that correlated with a large left hemispheric at risk territory, the decision was made to attempt revascularization of the occluded left internal carotid artery. This was achieved by developing a channel through the occluded internal carotid artery, deploying a distal embolic protection device, and placing a stent in the extracranial internal carotid artery at the level of the carotid bifurction. The distal embolic protection device was removed. A left MCA M1 segment thrombectomy was performed with manual aspiration and anterograde perfusion through the left MCA was restored.
The ICA stump site is probed with a microwire and microcatheter.
If the occlusion is transgressed, the microwire and catheter should be advanced until a patent segment of the ICA is reached.