POST PROCEDURE MANAGEMENT AND FOLLOW-UP

Post treatment evaluation is necessary for checking on the procedure end-result including technical success, patency rate, restenosis and complications.
The first 30 days after the procedure correspond to the "perioperative phase" when morbidity rate of carotid revascularization is higher and patients must be monitored for major or minor strokes using the NIHSS (National Institutes of Health Stroke Scale), for myocardial infarction using ECG and must undergo cardiac enzymes analysis.
Before hospital discharge a complete neurological evaluation, including NIHSS, should be performed.
In the event of stroke the Barthel Index and/or Rankin Score are highly recommended, particularly in case of a prior stroke, to assess the degree of disability.
The Barthel Index evaluates the functional dependency and is correlated to rehabilitation and long term cost of chronic care for the neurologically handicapped.
The modified Rankin Scale, roughly measuring social recovery in patient care, gets its clinical significance only at 90 days and beyond.
Intracranial embolism, haemorrhage and reperfusion injury are held responsible for neurologic deficits.
Risk of haemorrhage is increased by hypertension, high-grade ipsilateral stenosis, high-grade controlateral stenosis or occlusion and young age.
After a successful revascularization the mean arterial pressure should be reduced 10%-20% less than the baseline value in order to avoid cerebral reperfusion injury.
Elevated blood pressure after a procedure should be controlled using intravenous Diltiazem (5 mg/kg/ min. loading dose followed by a continuous intravenous infusion of 5 - 15 mg/ kg/ min.).
When hypertension is associated with headache or neurologic sequelae, Diltiazem is strongly recommended because it shows minimal cerebral vasodilator effects.
Carotid sinus dysfunction may provoke post-procedural prolonged bradycardia and/or hypotension requiring intravenous vasopressors or ionotropic agents.
After carotid endarterectomy and CAS, fluctuation in blood pressure may lead to neurologic complications.
Increased baroreflex sensitivity is linked to decreased carotid arterial distensibility in healthy people whereas baroreflex sensitivity is connected with the distortion and stretching of the carotid sinus in people with atherosclerotic disease.
Assuming that post-CAS hypotension is secondary to hypovolemia, the therapeutic strategy should be initially based on the administration of isotonic fluids and Atropine.
However, according to previous data from the treatment of post-carotid endarterectomy hypotension, a local lidocaine injection is said to be able to anesthetize the carotid sinus nerve and interrupt the afferent loop of the hypotension-inducing reflex.

In 1981, Sundt et al. described the "Hyperfusion Syndrome" with atypical migrainous phenomena, transient focal seizure activity and intracerebral haemorrhage.
Symptoms usually develop 5-7 days after carotid endarterectomy and are often preceded by unilateral headache. Elevated ipsilateral cerebral blood flow without a significant change in systemic blood pressure is held responsible for this syndrome that may be a serious complication of extracranial and intracranial angioplasty and stenting procedures.
Experience suggests that patients undergoing endovascular stenting procedures should be attentively monitored for hyperfusion, checking blood pressure, heart rate and anticoagulation.

After stent deployment, USCD is the method of choice for studying the carotid artery because it is a fast, non-invasive, relatively inexpensive method good for spotting significant stenosis, occlusion and other complications. Its only limit is to be operator-dependent.
Examinations should start within 24 h after procedure and then repeated at 6 and 12 months.
Each examination must include standard evaluation of the CCA, ICA, ECA and of the vertebral arteries.
The biomechanical properties of stent deployment modify blood flow velocity (BFV) in the carotid artery causing either increase in US velocity measurements or residual stenotic disease.

Consequently two standard criteria must be followed:
- peak in-stent systolic velocity > 125 cm/s
- internal carotid artery to common carotid artery ratio < 3,0

Anyway a correct analysis of the blood flow inside the stent is difficult because the hemodynamic effects of the stent cause blood flow alteration and turbulence.
Clinically suspected stent occlusion can be detected at early follow-up thanks to USCD considered the method of choice for studying restenosis rates after CAS.
When USCD shows abnormal findings, a DSA or a CTA must be added.
The morphological aspect of CCA and ICA as well as a complete analysis of the stent structure and of the inner lumen can be evaluated with multi-row spiral CTA using both axial and multiplanar-3D images.
DSA can be considered the gold standard technique but only in selected cases when abnormal findings are noticed.

Follow-up Protocol

References