Recurrence of stroke after cardiac surgery: insight into pathogenesis via diffusion-weighted and continuous arterial spin labeling perfusion magnetic resonance imaging.

摘要

STROKE AFTER CARDIAC surgery occurs with a higher incidence in patients with a history of prior stroke and is often delayed. Recurrence of stroke after cardiac surgery, thought to be primarily embolic in nature, has been noted to frequently follow the anatomic and vascular distribution of the previous stroke. Stroke is more frequent after aortic valve replacement for aortic stenosis than after coronary artery bypass grafting but may be, in both types of surgery, related to the extent of calcification in the ascending aorta or within the valve itself. Caplan and Hennerici hypothesized that vascular regions suffering from hypoperfusion and limited cerebrovascular reserve may be susceptible to emboli trapping. The case study presented offers unique findings and potential support for Caplan and Hennerici's hypothesis. Historic and clinical data are provided along with diffusion-weighted imaging (DWI) and relatively novel, continuous arterial spin labeling (CASL) perfusion magnetic resonance imaging data acquired on a 1.5 Tesla magnetic resonance imaging (MRI) system.