Neurological and ophthalmological phenomena after aortic conduit surgery. Transient neurological and visual signs have been observed in some patients after valved conduit replacement of the aortic valve and ascending aorta. Twenty-seven patients having valved conduit replacement between February 1982 and October 1988 were compared with 21 patients having combined aortic valve replacement (AVR) and ascending aorta (AA) graft replacement. Follow-up in 100% of both groups was obtained for 0.3-6.6 years (mean, 2.6 +/- 0.3 years). Among 20 surviving valved conduit patients, 10 (50.0%) experienced repetitive neurological and visual signs, including scotomata (seven), transient motor ischemic attacks (two), amaurosis fugax (four), and recurring attention lapses suggesting petit mal seizures (one). No patient with AVR + AA graft experienced any events (p = 0.004). All valved conduit and seven (53.8%) of AVR + AA graft patients were on warfarin (p = 0.0016). These events retained the same pattern although they diminished in frequency after 12 months in seven patients (70.0%) and after initiation of dipyridamole in two patients. Rehabilitation was similar in both groups: 18 of 20 (90.0%) valved conduit and 12 of 16 (75.0%) AVR + AA graft patients (p = NS). Transient, repetitive, nonprogressive neurological and ophthalmological phenomena are frequent after valved conduit replacement. The pathophysiological mechanism is unclear, but antiplatelet therapy may provide symptomatic control. 