A review of subclavian steal syndrome with clinical correlation

Abstract

Subclavian 'steal' phenomenon is a function of the proximal subclavian artery (SA) steno-occlusive disease, with subsequent retrograde blood flow in the ipsilateral vertebral artery (VA). The symptoms from the compromised vertebrobasilar and brachial blood flows constitute the subclavian steal syndrome (SSS), and include paroxysmal vertigo, drop attacks and/or arm claudication. Once thought to be rare, the emergence of new imaging techniques has drastically improved its diagnosis and prevalence. The syndrome, however, remains characteristically asymptomatic and solely poses no serious danger to the brain. Recent studies have shown a linear correlation between increasing arm blood pressure difference with the occurrence of symptoms. Atherosclerosis of the SA remains the most common cause. Doppler ultrasound is a useful screening tool, but the diagnosis must be confirmed by CT or MR angiography. Conservative treatment is the initial best therapy for this syndrome, with surgery reserved for refractory symptomatic cases. Percutaneous angioplasty and stenting, rather than bypass grafts of the subclavian artery, is the widely favored surgical approach. Nevertheless, large, prospective, randomized, controlled trials are needed to compare the long-term patency rates between the endovascular and open surgical techniques.

Figure 1

Schematic drawing showing a left-sided subclavian steal syndrome. Note that the lesion occurs just proximal to the origin of the left vertebral artery. SA – Subclavian Artery. (Redrawn and modified with permission from Grant et al., 2006).

Figure 2

Schematic diagram showing the retrograde from the left coronary artery through the mammary artery bypass grafts in a patient with left subclavian artery Stenosis. (Reproduced and modified with permission from Takach et al., 2006).

Figure 3

Posterior magnetic resonance angiographic (MRA) view of the aortic arch showing the atresia of the right proximal subclavian artery (RSA). An enlarged intercostal artery is seen emerging from the right side of the descending aorta. (Reproduced and modified with permission from Dainton et al, 2010).

Figure 4

Prevalence of grades of subclavian steal with increasing arm BP differential. Grade 1: BP differential 20–30 mmHg; Grade 2: BP differential 31–40 mmHg; Grade 3: BP differential 41–50 mmHg, Grade 4: BP differential >50. (Reproduced and modified with permission from Labropoulos et al., 2010).

Figure 5

Prevalence of symptoms and interventions in patients with SSS with increasing arm Blood Pressure (BP) differential. (Reproduced and modified with permission from Labropoulos et al., 2010).