Treatment of mechanically-induced vasospasm of the carotid artery in a primate using intra-arterial verapamil: a technical case report

Abstract

Background: Despite improvements in the safety and efficacy of endovascular procedures, considerable morbidity may still be attributed to vasospasm. Vasospasm has proven amenable to pharmacological intervention such as nitrates, intravenous calcium channel blockers (CCBs), and intra-arterial papaverine, particularly in small vessels. However, few studies have focused on medium to large vessel spasm. Here we report the use of an intra-arterial CCB, verapamil, to treat flow-limiting mechanically-induced spasm of the common carotid artery (CCA) in a primate. We believe this to be the first such report of its kind.

Case presentation: As part of a study assessing the placement feasibility and safety of a catheter capable of delivering intra-arterial cerebroprotective therapy, a female 16 kg baboon prophylaxed with intravenous nitroglycerin underwent transfemoral CCA catheterization with a metallic 6-Fr catheter without signs of acute spasm. The protocol dictated that the catheter remain in the CCA for 12 hours. Upon completion of the protocol, arteriography revealed a marked decrease in CCA size (mean cross-sectional area reduction = 31.6 +/- 1.9%) localized along the catheter length. Intra-arterial verapamil (2 mg/2cc) was injected and arteriography was performed 10 minutes later. Image analysis at 6 points along the CCA revealed a 21.0 +/- 1.7% mean increase in vessel diameter along the length of the catheter corresponding to a 46.7 +/- 4.0% mean increase in cross-sectional area. Mean systemic blood pressure did not deviate more than 10 mm Hg during the procedure.

Conclusions: Intraluminal CCBs like verapamil may constitute an effective endovascular treatment for mechanically-induced vasospasm in medium to large-sized vessels such as the CCA.

Figure 1

Anterior-posterior angiogram of right common carotid artery injection of a Papio anubis with a 6 Fr catheter in place both (A.) during vessel spasm on catheter, and (B.) 10 minutes after infusion of intraluminal verapamil (2 mg). Overlay images showing 6 Fr catheter position in CCA (gold) during spasm (C.) and after alleviation with verapamil (D.). Arrows (→) indicate tip of catheter.

Figure 2

Image analysis at 6 paired positions (Lines A-F) along catheter in common carotid artery both (A.) during vessel spasm, and (B.) 10 minutes after intraluminal verapamil (2 mg) administration. (C.) Raw data table includes vessel diameter measurements both pre and post-verapamil injection.

Figure 3

(A.) Bar graph depicting both the pre and post-verapamil mean vessel diameters from six positions along the length of the common carotid artery (CCA) (2.85 ± 0.14 mm and 3.45 ± 0.18 mm, respectively), and (B.) cross-sectional areas (6.41 ± 0.61 mm² and 9.39 ± 1.0 mm², respectively). Note the 46.7% increase in mean cross-sectional area after verapamil administration.