ABSTRACT
Bradycardia and Hypotension Hemodynamic instability, characterized by hypotension and sinus bradycardia, is fairly common during CAS (54). A dysfunction of adventitial stretch baroreceptors in the carotid sinus following balloon catheter dilatation and stent deployment, leading to sympathetic fibers inhibition and parasympathetic pathway stimulation, has been postulated as the trigger mechanism (55). Although benign, this hemodynamic response may rarely lead to asystole or profound hypotension.While in the early days of the procedure, a temporary transvenous pacemaker was inserted to prevent bradycardia; this rhythm disturbance can be effectively prevented with atropine (0.5 to 1.0 mg intravenously) administered routinely prior to balloon inflation/stenting. To treat hypotension, large volumes of normal saline and at times vasopressors (e.g., noradrenaline 5 to 10 mcg as repeated bolus and, if needed, 1 to 5 mcg/min as an infusion) may be required.
Spasm, Dissection, and Slow or No Flow Some degree of spasm of the ICA may be frequently observed at the level of the placement of the filter EPD. Spasms are usually asymptomatic, do not compromise flow, and resolve mostly spontaneously. If needed, nitroglycerin 50 to 200 mcg may be administered in the CCA through the guiding catheter or sheath. However, patients are frequently hypotensive during the procedure and, whenever possible, spontaneous resolution of the spasms should be awaited in order not to exacerbate hypotension. Vessel dissection is a rare event in CAS. It can happen in the ICA distally to the treated area, as propagation of a previously unrecognized dissection following angioplasty or as an injury occurring at the time of stent postdilatation. Measures to prevent dissection include the use of undersized balloons for predilatation, the coverage of the lesion with a nitinol stent having a safety margin of several millimeters distally and proximally to the lesion, and, more importantly, the performance of postdilatation with a slightly undersized balloon placed well within the limits of the stent.
