Dynamic Respiratory Tortuosity of the Vertebral Artery Ostium

To determine the prevalence of dynamic respiratory tortuosity (DRT) of the vertebral artery ostium (VAO) as well as to evaluate its correlation with in-stent restenosis (ISR) and stent fracture.

From March 2012 to June 2015, 178 consecutive patients (mean age 65.2±5.8 years; 124 men) with symptoms of atherosclerotic vertebrobasilar ischemia underwent angiography prior to stent implantation in the vertebral, subclavian, and/or carotid arteries. In this cohort, 54 patients (mean age 67.3±5.3 years; 40 men) had VAO stent implantation. Angiography of the vertebral artery was recorded in 2 phases with breath-hold: deep inspiration (DIP) and deep expiration (DEP). Obvious VAO tortuosity was defined as any VAO angle ≤120° in DIP. Obvious VAO-DRT was defined as any VAO angle increasing ≥60° from DIP to DEP. Computed tomography angiography (CTA) or digital subtraction angiography was used in follow-up to detect ISR and stent fracture.

Of the 178 patients in this study, 21 (11.8%) had obvious VAO tortuosity and 8 (4.5%) had obvious VAO-DRT. Two of the 21 patients with obvious VAO tortuosity also had obvious VAO-DRT. Three of the 54 VAO stent patients had VAO-DRT. There were no correlations between VAO-DRT and age, sex, risk factors, body mass index, chronic obstructive pulmonary disease, asthma, or obvious VAO tortuosity (p>0.05). Over a mean follow-up of 28±10 months, there were 4 (7.4%) asymptomatic VAO ISR cases. Two (3.7%) were occlusions at 6 and 12 months, respectively; both were associated with stent fracture in patients with obvious VAO-DRT before stenting. Both stents fractured at the tortuous VAO region. VAO-DRT was correlated with stent fracture (Spearman ρ=0.81, p<0.01) and ISR (Spearman ρ=0.55, p<0.01).

VAO-DRT could be a risk factor for stent fracture and restenosis after VAO stent implantation. Angiography in both inspiration and expiration phases, especially the latter, should be considered before VAO stenting. Using a shorter stent to avoid crossing the tortuosity could reduce the occurrence of fracture.