Forde, Inga

The treatment of epilepsy with vagus nerve stimulation can inadvertently cause obstructive and central sleep apnea (CSA). The mechanism for CSA seen in patients with a vagus nerve stimulator (VNS) is not fully known. We describe the case of a 13-year-old girl in whom VNS activation induced tachypnea and post-hyperventilation central apnea. Following adjustment of VNS settings, the post-hyperventilation CSA resolved. Polysomnography may assist with management when patients with epilepsy develop sleep disruption after VNS placement.

Objective Bicuspid aortic valve (BAV) is associated with a higher risk of type A aortic dissection (AD) compared with tricuspid aortic valve (TAV). We sought to study differences between patients with BAV and TAV with AD. Design and setting Observational descriptive analysis of clinical, imaging and pathological characteristics of all patients with confirmed BAV and AD from 1980–2010, compared with a consecutive TAV group with AD. Results Of 47 patients with BAV (mean age 58±14, 77% male), 31 (66%) had acute AD, 16 (34%) had chronic AD, 40 (85%) had typical BAV, 32 (68%) had hypertension and 11 (23%) had previous aortic coarctation repair. Of 53 patients with TAV (mean age 66±13 (p=0.007), 76% male), 34 (66%) had acute AD (p=1.0) and 46 (87%) had hypertension (p=0.03). More patients with BAV had known aortic dilatation prior to AD (49% versus 17%, p=0.001). Presentation symptoms were identical between groups (p=NS). Maximal ascending aortic diameter at AD was higher in patients with BAV (66±15 mm vs 56±11 mm, p=0.0004). Previous aortic valve replacement (AVR) was more common in BAV (23% vs 6%, p=0.02). Of 11 patients with BAV with previous isolated AVR, 7 had ≥moderate ascending aorta dilatation at the time of surgery. Patients with BAV had increased aortic jet velocity (28% vs 10%) and more severe aortic stenosis (19% vs 0%) at presentation (p=0.04 and 0.002, respectively). In acute AD, aortic medial degeneration affected 75% of BAV specimens and 41% TAV specimens (p=0.01) while aortic atherosclerosis was more frequent in TAV (56% vs 26%, p=0.02). Conclusions Compared with patients with TAV, patients with BAV with type A AD are younger, have less hypertension, more valve stenosis and previous AVR, higher maximal aortic dimension, worse aortic medial degeneration, high prevalence of aortic coarctation, and 1 out of 2 have known aortic dilatation prior to AD. Implementation of current guidelines could have theoretically prevented AD in several patients with BAV.