Minimal Contrast Use in Carotid Stenting: Avoiding Contrast Pitfalls

Carotid artery stenting (CAS) is now widely utilized as a less invasive alternative to carotid endarterectomy for the prevention of stroke caused by extracranial bifurcation carotid artery stenosis. The procedure involves diagnostic angiography, the extent of which is determined by the anatomic information obtained by preprocedural noninvasive studies, but which should include an accurate evaluation of lesion severity, the carotid bifurcation, ipsilateral intracranial anatomy and the anatomy of the common carotid artery (CCA). The interventional aspects of the procedure then follow. Patients with carotid disease are similar in demographic to those with coronary artery disease, the group in which many of the contrast-induced nephropathy (CIN) trials have been conducted, and hence the same precautions with regard to avoidance of CIN are employed, namely, preprocedural avoidance of nephrotoxic drugs, ± use of N-acetylcysteine, use of iso- or low-osmolar contrast, reduced volume of contrast used and additional intravenous fluids given. In addition, carotid stenting has the complication of associated hypotension which is invariably noted after balloon dilatation, sometimes requiring aggressive volume expansion and intravenous phenylephrine. Hence, in CAS, high contrast volume should be avoided. Case Report. A CAS case was performed using the standard Lenox Hill Hospital protocol⁵ which describes usual procedural practice with regard to contrast use and renal protection. The patient was a 73-year-old female referred for CAS due to a symptomatic carotid artery stenosis which was diagnosed by carotid artery duplex ultrasound, after presenting with a transient episode of slurred speech and left facial weakness. She had the following risk factors: hypertension, hypercholesterolemia and known coronary artery disease with prior coronary intervention. Her creatinine was 1.5 mg/dl (GFR 36 ml/min/1.73 m²)⁷ pre-procedure. All antihypertensive medication was withheld on the day of the procedure, and 1,200 mg of N-acetylcysteine (Mucomyst^®, Bristol-Myers Squibb) was given preprocedure, with an additional 2 doses of 1,200 mg given postprocedure. Visipaque™ 320 (GE Healthcare, United Kingdom) (iodixanol, isosmolar, nonionic) was the contrast agent used, and this was diluted with heparinized saline in a ratio of 1:1 prior to each injection. The case proceeded with 4-vessel angiography using a Vitek catheter (Cook, Inc., Bloomington, Indiana). The following digitally-subtracted views were obtained: LCCA – LAO and lateral; RCCA – RAO and lateral; right cerebral circulation – AP and lateral. Each carotid view required approximately 3 ml of contrast diluted with 2–3 ml of saline, and each cerebral view required approximately 6 ml of diluted contrast. A Shuttle sheath was advanced into the RCCA and a final RAO image using 3 ml of diluted contrast was taken in order to landmark the lesion. This last landmarked digitally-subtracted image then allowed the placement of an embolic protection device, balloon predilatation, stent placement and balloon postdilatation, all without any further need for contrast. Postprocedure views included: RAO view of the RCCA using 3 ml of diluted contrast, and AP and lateral right cerebral circulation views requiring approximately 6 ml of diluted contrast each. Finally, femoral angiography requiring 3–5 ml of diluted contrast was undertaken prior to a vascular closure device insertion. A total of 35 ml of contrast was used for the entire procedure. Relevant patient care included the use of 2.5 liters of intravenous fluid (normal saline), pre- and postprocedure and intraprocedural atropine, which preemptively treated the expected hypotension and bradycardia. The patient’s 24-hour creatinine was 1.8 mg/dl (GFR 29 ml/min/1.732),⁷ and the patient was discharged with no complications and received physician follow up. Conclusion Patients with baseline renal insufficiency undergoing CAS require strict adherence to renal protective protocols and procedural minimalization of contrast media. This case demonstrates that experienced CAS operators do not require high volumes of contrast to safely perform the procedure. Providing optimal technique is not compromised, minimizing contrast volume in carotid stenting will enhance the safety and 30-day outcomes associated with the procedure.

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