====== Subclavian artery stenosis ======

Radiologically demonstrable [[stenosis]] of the [[subclavian artery]] or [[innominate artery]] is present in approximately 17%. Of these, 2.5% have angiographic flow reversal in [[vertebral artery]]. Only 5.3 % of those with angiographic steal have neurologic symptoms
((Fields WS, Lemak NA. Joint Study of extracranial arterial occlusion. VII. Subclavian steal–a review of 168 cases. JAMA. 1972; 222:1139–1143)).

===== Clinical features =====
The 5 D’s of VBI i.e.,[[diplopia]], [[dysarthria]], defective [[vision]], [[dizziness]] and [[drop attack]]s. Other symptoms include [[headache]], [[nystagmus]], [[hearing loss]] and [[focal seizure]]s
((Fields WS. Reflections on "the subclavian steal". Stroke. 1970; 1:320–324))
((Smith JM, Koury HI, Hafner CD, Welling RE. Subclavian steal syndrome. A review of 59 consecutive cases. J Cardiovasc Surg (Torino). 1994; 35:11–14)).

The arterial stenosis is proximal to the origin of VA. Symptoms are induced by exercise or exertion
using the arm ipsilateral to the stenosis. The increased flow demand due to the exertion results in retrograde blood flow through the VA. The neurological symptoms may be because of continuous brainstem ischemia or more commonly, ischemia due to ipsilateral arm exercise or exertion
((Brook I. Bacteriology of Intracranial Abscess in Children. J Neurosurg. 1981; 54:484–488)).

===== Indications for endovascular intervention =====

Symptomatic subclavian artery stenosis i.e., stenosis resulting in [[subclavian steal syndrome]].

===== Endovascular intervention =====

This includes [[angioplasty]] and [[stenting]]. A balloon mounted stent e.g., Express LD may be used, as the stent is deployed concurrently with angioplasty
((Khan SH, Young PH, Ringer AJ. Endovascular treatment of subclavian artery stenosis associated with vertebral artery pseudoaneurysm. Clin Neurol Neurosurg. 2012; 114:754–757)).

However, if the stenosis is particularly severe (e.g., <2 mm), pre-dilatation may be performed by a smaller balloon to achieve a caliber of 4 mm at site of stenosis. Normal antegrade blood flow is restored following successful angioplasty and stenting.

===== Postoperative management =====

The patient is monitored at least overnight in NSICU.

After stenting, the patient remains on dual antiplatelet therapy (ASA+Plavix) for at least 1 month,
and ASA alone indefinitely.

Follow-up study in 3–6 months, which could be CTA, Doppler ultrasonography or catheter
angiogram.

===== Complications of angioplasty and stenting =====

The frequency of complications is 17.8% (of 73 procedures) for innominate and VA angioplasty and stenting. These include access-site bleeding and distal embolization
((Sullivan TM, Gray BH, Bacharach JM, Perl J,2nd, Childs MB, Modzelewski L, Beven EG. Angioplasty and primary stenting of the subclavian, innominate, and common carotid arteries in 83 patients. J Vasc Surg. 1998; 28:1059–1065)).

===== References =====